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1/*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 *
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
17 *
18 * tiny-shmem:
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 *
21 * This file is released under the GPL.
22 */
23
24#include <linux/fs.h>
25#include <linux/init.h>
26#include <linux/vfs.h>
27#include <linux/mount.h>
28#include <linux/ramfs.h>
29#include <linux/pagemap.h>
30#include <linux/file.h>
31#include <linux/mm.h>
32#include <linux/random.h>
33#include <linux/sched/signal.h>
34#include <linux/export.h>
35#include <linux/swap.h>
36#include <linux/uio.h>
37#include <linux/khugepaged.h>
38#include <linux/hugetlb.h>
39#include <linux/frontswap.h>
40#include <linux/fs_parser.h>
41
42#include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */
43
44static struct vfsmount *shm_mnt;
45
46#ifdef CONFIG_SHMEM
47/*
48 * This virtual memory filesystem is heavily based on the ramfs. It
49 * extends ramfs by the ability to use swap and honor resource limits
50 * which makes it a completely usable filesystem.
51 */
52
53#include <linux/xattr.h>
54#include <linux/exportfs.h>
55#include <linux/posix_acl.h>
56#include <linux/posix_acl_xattr.h>
57#include <linux/mman.h>
58#include <linux/string.h>
59#include <linux/slab.h>
60#include <linux/backing-dev.h>
61#include <linux/shmem_fs.h>
62#include <linux/writeback.h>
63#include <linux/blkdev.h>
64#include <linux/pagevec.h>
65#include <linux/percpu_counter.h>
66#include <linux/falloc.h>
67#include <linux/splice.h>
68#include <linux/security.h>
69#include <linux/swapops.h>
70#include <linux/mempolicy.h>
71#include <linux/namei.h>
72#include <linux/ctype.h>
73#include <linux/migrate.h>
74#include <linux/highmem.h>
75#include <linux/seq_file.h>
76#include <linux/magic.h>
77#include <linux/syscalls.h>
78#include <linux/fcntl.h>
79#include <uapi/linux/memfd.h>
80#include <linux/userfaultfd_k.h>
81#include <linux/rmap.h>
82#include <linux/uuid.h>
83
84#include <linux/uaccess.h>
85
86#include "internal.h"
87
88#define BLOCKS_PER_PAGE (PAGE_SIZE/512)
89#define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
90
91/* Pretend that each entry is of this size in directory's i_size */
92#define BOGO_DIRENT_SIZE 20
93
94/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
95#define SHORT_SYMLINK_LEN 128
96
97/*
98 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
99 * inode->i_private (with i_mutex making sure that it has only one user at
100 * a time): we would prefer not to enlarge the shmem inode just for that.
101 */
102struct shmem_falloc {
103 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
104 pgoff_t start; /* start of range currently being fallocated */
105 pgoff_t next; /* the next page offset to be fallocated */
106 pgoff_t nr_falloced; /* how many new pages have been fallocated */
107 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
108};
109
110struct shmem_options {
111 unsigned long long blocks;
112 unsigned long long inodes;
113 struct mempolicy *mpol;
114 kuid_t uid;
115 kgid_t gid;
116 umode_t mode;
117 bool full_inums;
118 int huge;
119 int seen;
120#define SHMEM_SEEN_BLOCKS 1
121#define SHMEM_SEEN_INODES 2
122#define SHMEM_SEEN_HUGE 4
123#define SHMEM_SEEN_INUMS 8
124};
125
126#ifdef CONFIG_TMPFS
127static unsigned long shmem_default_max_blocks(void)
128{
129 return totalram_pages() / 2;
130}
131
132static unsigned long shmem_default_max_inodes(void)
133{
134 unsigned long nr_pages = totalram_pages();
135
136 return min(nr_pages - totalhigh_pages(), nr_pages / 2);
137}
138#endif
139
140static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
141static int shmem_replace_page(struct page **pagep, gfp_t gfp,
142 struct shmem_inode_info *info, pgoff_t index);
143static int shmem_swapin_page(struct inode *inode, pgoff_t index,
144 struct page **pagep, enum sgp_type sgp,
145 gfp_t gfp, struct vm_area_struct *vma,
146 vm_fault_t *fault_type);
147static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
148 struct page **pagep, enum sgp_type sgp,
149 gfp_t gfp, struct vm_area_struct *vma,
150 struct vm_fault *vmf, vm_fault_t *fault_type);
151
152int shmem_getpage(struct inode *inode, pgoff_t index,
153 struct page **pagep, enum sgp_type sgp)
154{
155 return shmem_getpage_gfp(inode, index, pagep, sgp,
156 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
157}
158
159static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
160{
161 return sb->s_fs_info;
162}
163
164/*
165 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
166 * for shared memory and for shared anonymous (/dev/zero) mappings
167 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
168 * consistent with the pre-accounting of private mappings ...
169 */
170static inline int shmem_acct_size(unsigned long flags, loff_t size)
171{
172 return (flags & VM_NORESERVE) ?
173 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
174}
175
176static inline void shmem_unacct_size(unsigned long flags, loff_t size)
177{
178 if (!(flags & VM_NORESERVE))
179 vm_unacct_memory(VM_ACCT(size));
180}
181
182static inline int shmem_reacct_size(unsigned long flags,
183 loff_t oldsize, loff_t newsize)
184{
185 if (!(flags & VM_NORESERVE)) {
186 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
187 return security_vm_enough_memory_mm(current->mm,
188 VM_ACCT(newsize) - VM_ACCT(oldsize));
189 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
190 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
191 }
192 return 0;
193}
194
195/*
196 * ... whereas tmpfs objects are accounted incrementally as
197 * pages are allocated, in order to allow large sparse files.
198 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
199 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
200 */
201static inline int shmem_acct_block(unsigned long flags, long pages)
202{
203 if (!(flags & VM_NORESERVE))
204 return 0;
205
206 return security_vm_enough_memory_mm(current->mm,
207 pages * VM_ACCT(PAGE_SIZE));
208}
209
210static inline void shmem_unacct_blocks(unsigned long flags, long pages)
211{
212 if (flags & VM_NORESERVE)
213 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
214}
215
216static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
217{
218 struct shmem_inode_info *info = SHMEM_I(inode);
219 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
220
221 if (shmem_acct_block(info->flags, pages))
222 return false;
223
224 if (sbinfo->max_blocks) {
225 if (percpu_counter_compare(&sbinfo->used_blocks,
226 sbinfo->max_blocks - pages) > 0)
227 goto unacct;
228 percpu_counter_add(&sbinfo->used_blocks, pages);
229 }
230
231 return true;
232
233unacct:
234 shmem_unacct_blocks(info->flags, pages);
235 return false;
236}
237
238static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
239{
240 struct shmem_inode_info *info = SHMEM_I(inode);
241 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
242
243 if (sbinfo->max_blocks)
244 percpu_counter_sub(&sbinfo->used_blocks, pages);
245 shmem_unacct_blocks(info->flags, pages);
246}
247
248static const struct super_operations shmem_ops;
249static const struct address_space_operations shmem_aops;
250static const struct file_operations shmem_file_operations;
251static const struct inode_operations shmem_inode_operations;
252static const struct inode_operations shmem_dir_inode_operations;
253static const struct inode_operations shmem_special_inode_operations;
254static const struct vm_operations_struct shmem_vm_ops;
255static struct file_system_type shmem_fs_type;
256
257bool vma_is_shmem(struct vm_area_struct *vma)
258{
259 return vma->vm_ops == &shmem_vm_ops;
260}
261
262static LIST_HEAD(shmem_swaplist);
263static DEFINE_MUTEX(shmem_swaplist_mutex);
264
265/*
266 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
267 * produces a novel ino for the newly allocated inode.
268 *
269 * It may also be called when making a hard link to permit the space needed by
270 * each dentry. However, in that case, no new inode number is needed since that
271 * internally draws from another pool of inode numbers (currently global
272 * get_next_ino()). This case is indicated by passing NULL as inop.
273 */
274#define SHMEM_INO_BATCH 1024
275static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
276{
277 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
278 ino_t ino;
279
280 if (!(sb->s_flags & SB_KERNMOUNT)) {
281 spin_lock(&sbinfo->stat_lock);
282 if (sbinfo->max_inodes) {
283 if (!sbinfo->free_inodes) {
284 spin_unlock(&sbinfo->stat_lock);
285 return -ENOSPC;
286 }
287 sbinfo->free_inodes--;
288 }
289 if (inop) {
290 ino = sbinfo->next_ino++;
291 if (unlikely(is_zero_ino(ino)))
292 ino = sbinfo->next_ino++;
293 if (unlikely(!sbinfo->full_inums &&
294 ino > UINT_MAX)) {
295 /*
296 * Emulate get_next_ino uint wraparound for
297 * compatibility
298 */
299 if (IS_ENABLED(CONFIG_64BIT))
300 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
301 __func__, MINOR(sb->s_dev));
302 sbinfo->next_ino = 1;
303 ino = sbinfo->next_ino++;
304 }
305 *inop = ino;
306 }
307 spin_unlock(&sbinfo->stat_lock);
308 } else if (inop) {
309 /*
310 * __shmem_file_setup, one of our callers, is lock-free: it
311 * doesn't hold stat_lock in shmem_reserve_inode since
312 * max_inodes is always 0, and is called from potentially
313 * unknown contexts. As such, use a per-cpu batched allocator
314 * which doesn't require the per-sb stat_lock unless we are at
315 * the batch boundary.
316 *
317 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
318 * shmem mounts are not exposed to userspace, so we don't need
319 * to worry about things like glibc compatibility.
320 */
321 ino_t *next_ino;
322 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
323 ino = *next_ino;
324 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
325 spin_lock(&sbinfo->stat_lock);
326 ino = sbinfo->next_ino;
327 sbinfo->next_ino += SHMEM_INO_BATCH;
328 spin_unlock(&sbinfo->stat_lock);
329 if (unlikely(is_zero_ino(ino)))
330 ino++;
331 }
332 *inop = ino;
333 *next_ino = ++ino;
334 put_cpu();
335 }
336
337 return 0;
338}
339
340static void shmem_free_inode(struct super_block *sb)
341{
342 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
343 if (sbinfo->max_inodes) {
344 spin_lock(&sbinfo->stat_lock);
345 sbinfo->free_inodes++;
346 spin_unlock(&sbinfo->stat_lock);
347 }
348}
349
350/**
351 * shmem_recalc_inode - recalculate the block usage of an inode
352 * @inode: inode to recalc
353 *
354 * We have to calculate the free blocks since the mm can drop
355 * undirtied hole pages behind our back.
356 *
357 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
358 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
359 *
360 * It has to be called with the spinlock held.
361 */
362static void shmem_recalc_inode(struct inode *inode)
363{
364 struct shmem_inode_info *info = SHMEM_I(inode);
365 long freed;
366
367 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
368 if (freed > 0) {
369 info->alloced -= freed;
370 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
371 shmem_inode_unacct_blocks(inode, freed);
372 }
373}
374
375bool shmem_charge(struct inode *inode, long pages)
376{
377 struct shmem_inode_info *info = SHMEM_I(inode);
378 unsigned long flags;
379
380 if (!shmem_inode_acct_block(inode, pages))
381 return false;
382
383 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
384 inode->i_mapping->nrpages += pages;
385
386 spin_lock_irqsave(&info->lock, flags);
387 info->alloced += pages;
388 inode->i_blocks += pages * BLOCKS_PER_PAGE;
389 shmem_recalc_inode(inode);
390 spin_unlock_irqrestore(&info->lock, flags);
391
392 return true;
393}
394
395void shmem_uncharge(struct inode *inode, long pages)
396{
397 struct shmem_inode_info *info = SHMEM_I(inode);
398 unsigned long flags;
399
400 /* nrpages adjustment done by __delete_from_page_cache() or caller */
401
402 spin_lock_irqsave(&info->lock, flags);
403 info->alloced -= pages;
404 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
405 shmem_recalc_inode(inode);
406 spin_unlock_irqrestore(&info->lock, flags);
407
408 shmem_inode_unacct_blocks(inode, pages);
409}
410
411/*
412 * Replace item expected in xarray by a new item, while holding xa_lock.
413 */
414static int shmem_replace_entry(struct address_space *mapping,
415 pgoff_t index, void *expected, void *replacement)
416{
417 XA_STATE(xas, &mapping->i_pages, index);
418 void *item;
419
420 VM_BUG_ON(!expected);
421 VM_BUG_ON(!replacement);
422 item = xas_load(&xas);
423 if (item != expected)
424 return -ENOENT;
425 xas_store(&xas, replacement);
426 return 0;
427}
428
429/*
430 * Sometimes, before we decide whether to proceed or to fail, we must check
431 * that an entry was not already brought back from swap by a racing thread.
432 *
433 * Checking page is not enough: by the time a SwapCache page is locked, it
434 * might be reused, and again be SwapCache, using the same swap as before.
435 */
436static bool shmem_confirm_swap(struct address_space *mapping,
437 pgoff_t index, swp_entry_t swap)
438{
439 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
440}
441
442/*
443 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
444 *
445 * SHMEM_HUGE_NEVER:
446 * disables huge pages for the mount;
447 * SHMEM_HUGE_ALWAYS:
448 * enables huge pages for the mount;
449 * SHMEM_HUGE_WITHIN_SIZE:
450 * only allocate huge pages if the page will be fully within i_size,
451 * also respect fadvise()/madvise() hints;
452 * SHMEM_HUGE_ADVISE:
453 * only allocate huge pages if requested with fadvise()/madvise();
454 */
455
456#define SHMEM_HUGE_NEVER 0
457#define SHMEM_HUGE_ALWAYS 1
458#define SHMEM_HUGE_WITHIN_SIZE 2
459#define SHMEM_HUGE_ADVISE 3
460
461/*
462 * Special values.
463 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
464 *
465 * SHMEM_HUGE_DENY:
466 * disables huge on shm_mnt and all mounts, for emergency use;
467 * SHMEM_HUGE_FORCE:
468 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
469 *
470 */
471#define SHMEM_HUGE_DENY (-1)
472#define SHMEM_HUGE_FORCE (-2)
473
474#ifdef CONFIG_TRANSPARENT_HUGEPAGE
475/* ifdef here to avoid bloating shmem.o when not necessary */
476
477static int shmem_huge __read_mostly;
478
479#if defined(CONFIG_SYSFS)
480static int shmem_parse_huge(const char *str)
481{
482 if (!strcmp(str, "never"))
483 return SHMEM_HUGE_NEVER;
484 if (!strcmp(str, "always"))
485 return SHMEM_HUGE_ALWAYS;
486 if (!strcmp(str, "within_size"))
487 return SHMEM_HUGE_WITHIN_SIZE;
488 if (!strcmp(str, "advise"))
489 return SHMEM_HUGE_ADVISE;
490 if (!strcmp(str, "deny"))
491 return SHMEM_HUGE_DENY;
492 if (!strcmp(str, "force"))
493 return SHMEM_HUGE_FORCE;
494 return -EINVAL;
495}
496#endif
497
498#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
499static const char *shmem_format_huge(int huge)
500{
501 switch (huge) {
502 case SHMEM_HUGE_NEVER:
503 return "never";
504 case SHMEM_HUGE_ALWAYS:
505 return "always";
506 case SHMEM_HUGE_WITHIN_SIZE:
507 return "within_size";
508 case SHMEM_HUGE_ADVISE:
509 return "advise";
510 case SHMEM_HUGE_DENY:
511 return "deny";
512 case SHMEM_HUGE_FORCE:
513 return "force";
514 default:
515 VM_BUG_ON(1);
516 return "bad_val";
517 }
518}
519#endif
520
521static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
522 struct shrink_control *sc, unsigned long nr_to_split)
523{
524 LIST_HEAD(list), *pos, *next;
525 LIST_HEAD(to_remove);
526 struct inode *inode;
527 struct shmem_inode_info *info;
528 struct page *page;
529 unsigned long batch = sc ? sc->nr_to_scan : 128;
530 int removed = 0, split = 0;
531
532 if (list_empty(&sbinfo->shrinklist))
533 return SHRINK_STOP;
534
535 spin_lock(&sbinfo->shrinklist_lock);
536 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
537 info = list_entry(pos, struct shmem_inode_info, shrinklist);
538
539 /* pin the inode */
540 inode = igrab(&info->vfs_inode);
541
542 /* inode is about to be evicted */
543 if (!inode) {
544 list_del_init(&info->shrinklist);
545 removed++;
546 goto next;
547 }
548
549 /* Check if there's anything to gain */
550 if (round_up(inode->i_size, PAGE_SIZE) ==
551 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
552 list_move(&info->shrinklist, &to_remove);
553 removed++;
554 goto next;
555 }
556
557 list_move(&info->shrinklist, &list);
558next:
559 if (!--batch)
560 break;
561 }
562 spin_unlock(&sbinfo->shrinklist_lock);
563
564 list_for_each_safe(pos, next, &to_remove) {
565 info = list_entry(pos, struct shmem_inode_info, shrinklist);
566 inode = &info->vfs_inode;
567 list_del_init(&info->shrinklist);
568 iput(inode);
569 }
570
571 list_for_each_safe(pos, next, &list) {
572 int ret;
573
574 info = list_entry(pos, struct shmem_inode_info, shrinklist);
575 inode = &info->vfs_inode;
576
577 if (nr_to_split && split >= nr_to_split)
578 goto leave;
579
580 page = find_get_page(inode->i_mapping,
581 (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
582 if (!page)
583 goto drop;
584
585 /* No huge page at the end of the file: nothing to split */
586 if (!PageTransHuge(page)) {
587 put_page(page);
588 goto drop;
589 }
590
591 /*
592 * Leave the inode on the list if we failed to lock
593 * the page at this time.
594 *
595 * Waiting for the lock may lead to deadlock in the
596 * reclaim path.
597 */
598 if (!trylock_page(page)) {
599 put_page(page);
600 goto leave;
601 }
602
603 ret = split_huge_page(page);
604 unlock_page(page);
605 put_page(page);
606
607 /* If split failed leave the inode on the list */
608 if (ret)
609 goto leave;
610
611 split++;
612drop:
613 list_del_init(&info->shrinklist);
614 removed++;
615leave:
616 iput(inode);
617 }
618
619 spin_lock(&sbinfo->shrinklist_lock);
620 list_splice_tail(&list, &sbinfo->shrinklist);
621 sbinfo->shrinklist_len -= removed;
622 spin_unlock(&sbinfo->shrinklist_lock);
623
624 return split;
625}
626
627static long shmem_unused_huge_scan(struct super_block *sb,
628 struct shrink_control *sc)
629{
630 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
631
632 if (!READ_ONCE(sbinfo->shrinklist_len))
633 return SHRINK_STOP;
634
635 return shmem_unused_huge_shrink(sbinfo, sc, 0);
636}
637
638static long shmem_unused_huge_count(struct super_block *sb,
639 struct shrink_control *sc)
640{
641 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
642 return READ_ONCE(sbinfo->shrinklist_len);
643}
644#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
645
646#define shmem_huge SHMEM_HUGE_DENY
647
648static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
649 struct shrink_control *sc, unsigned long nr_to_split)
650{
651 return 0;
652}
653#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
654
655static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo)
656{
657 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
658 (shmem_huge == SHMEM_HUGE_FORCE || sbinfo->huge) &&
659 shmem_huge != SHMEM_HUGE_DENY)
660 return true;
661 return false;
662}
663
664/*
665 * Like add_to_page_cache_locked, but error if expected item has gone.
666 */
667static int shmem_add_to_page_cache(struct page *page,
668 struct address_space *mapping,
669 pgoff_t index, void *expected, gfp_t gfp,
670 struct mm_struct *charge_mm)
671{
672 XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
673 unsigned long i = 0;
674 unsigned long nr = compound_nr(page);
675 int error;
676
677 VM_BUG_ON_PAGE(PageTail(page), page);
678 VM_BUG_ON_PAGE(index != round_down(index, nr), page);
679 VM_BUG_ON_PAGE(!PageLocked(page), page);
680 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
681 VM_BUG_ON(expected && PageTransHuge(page));
682
683 page_ref_add(page, nr);
684 page->mapping = mapping;
685 page->index = index;
686
687 if (!PageSwapCache(page)) {
688 error = mem_cgroup_charge(page, charge_mm, gfp);
689 if (error) {
690 if (PageTransHuge(page)) {
691 count_vm_event(THP_FILE_FALLBACK);
692 count_vm_event(THP_FILE_FALLBACK_CHARGE);
693 }
694 goto error;
695 }
696 }
697 cgroup_throttle_swaprate(page, gfp);
698
699 do {
700 void *entry;
701 xas_lock_irq(&xas);
702 entry = xas_find_conflict(&xas);
703 if (entry != expected)
704 xas_set_err(&xas, -EEXIST);
705 xas_create_range(&xas);
706 if (xas_error(&xas))
707 goto unlock;
708next:
709 xas_store(&xas, page);
710 if (++i < nr) {
711 xas_next(&xas);
712 goto next;
713 }
714 if (PageTransHuge(page)) {
715 count_vm_event(THP_FILE_ALLOC);
716 __inc_node_page_state(page, NR_SHMEM_THPS);
717 }
718 mapping->nrpages += nr;
719 __mod_lruvec_page_state(page, NR_FILE_PAGES, nr);
720 __mod_lruvec_page_state(page, NR_SHMEM, nr);
721unlock:
722 xas_unlock_irq(&xas);
723 } while (xas_nomem(&xas, gfp));
724
725 if (xas_error(&xas)) {
726 error = xas_error(&xas);
727 goto error;
728 }
729
730 return 0;
731error:
732 page->mapping = NULL;
733 page_ref_sub(page, nr);
734 return error;
735}
736
737/*
738 * Like delete_from_page_cache, but substitutes swap for page.
739 */
740static void shmem_delete_from_page_cache(struct page *page, void *radswap)
741{
742 struct address_space *mapping = page->mapping;
743 int error;
744
745 VM_BUG_ON_PAGE(PageCompound(page), page);
746
747 xa_lock_irq(&mapping->i_pages);
748 error = shmem_replace_entry(mapping, page->index, page, radswap);
749 page->mapping = NULL;
750 mapping->nrpages--;
751 __dec_lruvec_page_state(page, NR_FILE_PAGES);
752 __dec_lruvec_page_state(page, NR_SHMEM);
753 xa_unlock_irq(&mapping->i_pages);
754 put_page(page);
755 BUG_ON(error);
756}
757
758/*
759 * Remove swap entry from page cache, free the swap and its page cache.
760 */
761static int shmem_free_swap(struct address_space *mapping,
762 pgoff_t index, void *radswap)
763{
764 void *old;
765
766 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
767 if (old != radswap)
768 return -ENOENT;
769 free_swap_and_cache(radix_to_swp_entry(radswap));
770 return 0;
771}
772
773/*
774 * Determine (in bytes) how many of the shmem object's pages mapped by the
775 * given offsets are swapped out.
776 *
777 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
778 * as long as the inode doesn't go away and racy results are not a problem.
779 */
780unsigned long shmem_partial_swap_usage(struct address_space *mapping,
781 pgoff_t start, pgoff_t end)
782{
783 XA_STATE(xas, &mapping->i_pages, start);
784 struct page *page;
785 unsigned long swapped = 0;
786
787 rcu_read_lock();
788 xas_for_each(&xas, page, end - 1) {
789 if (xas_retry(&xas, page))
790 continue;
791 if (xa_is_value(page))
792 swapped++;
793
794 if (need_resched()) {
795 xas_pause(&xas);
796 cond_resched_rcu();
797 }
798 }
799
800 rcu_read_unlock();
801
802 return swapped << PAGE_SHIFT;
803}
804
805/*
806 * Determine (in bytes) how many of the shmem object's pages mapped by the
807 * given vma is swapped out.
808 *
809 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
810 * as long as the inode doesn't go away and racy results are not a problem.
811 */
812unsigned long shmem_swap_usage(struct vm_area_struct *vma)
813{
814 struct inode *inode = file_inode(vma->vm_file);
815 struct shmem_inode_info *info = SHMEM_I(inode);
816 struct address_space *mapping = inode->i_mapping;
817 unsigned long swapped;
818
819 /* Be careful as we don't hold info->lock */
820 swapped = READ_ONCE(info->swapped);
821
822 /*
823 * The easier cases are when the shmem object has nothing in swap, or
824 * the vma maps it whole. Then we can simply use the stats that we
825 * already track.
826 */
827 if (!swapped)
828 return 0;
829
830 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
831 return swapped << PAGE_SHIFT;
832
833 /* Here comes the more involved part */
834 return shmem_partial_swap_usage(mapping,
835 linear_page_index(vma, vma->vm_start),
836 linear_page_index(vma, vma->vm_end));
837}
838
839/*
840 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
841 */
842void shmem_unlock_mapping(struct address_space *mapping)
843{
844 struct pagevec pvec;
845 pgoff_t indices[PAGEVEC_SIZE];
846 pgoff_t index = 0;
847
848 pagevec_init(&pvec);
849 /*
850 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
851 */
852 while (!mapping_unevictable(mapping)) {
853 /*
854 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
855 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
856 */
857 pvec.nr = find_get_entries(mapping, index,
858 PAGEVEC_SIZE, pvec.pages, indices);
859 if (!pvec.nr)
860 break;
861 index = indices[pvec.nr - 1] + 1;
862 pagevec_remove_exceptionals(&pvec);
863 check_move_unevictable_pages(&pvec);
864 pagevec_release(&pvec);
865 cond_resched();
866 }
867}
868
869/*
870 * Check whether a hole-punch or truncation needs to split a huge page,
871 * returning true if no split was required, or the split has been successful.
872 *
873 * Eviction (or truncation to 0 size) should never need to split a huge page;
874 * but in rare cases might do so, if shmem_undo_range() failed to trylock on
875 * head, and then succeeded to trylock on tail.
876 *
877 * A split can only succeed when there are no additional references on the
878 * huge page: so the split below relies upon find_get_entries() having stopped
879 * when it found a subpage of the huge page, without getting further references.
880 */
881static bool shmem_punch_compound(struct page *page, pgoff_t start, pgoff_t end)
882{
883 if (!PageTransCompound(page))
884 return true;
885
886 /* Just proceed to delete a huge page wholly within the range punched */
887 if (PageHead(page) &&
888 page->index >= start && page->index + HPAGE_PMD_NR <= end)
889 return true;
890
891 /* Try to split huge page, so we can truly punch the hole or truncate */
892 return split_huge_page(page) >= 0;
893}
894
895/*
896 * Remove range of pages and swap entries from page cache, and free them.
897 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
898 */
899static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
900 bool unfalloc)
901{
902 struct address_space *mapping = inode->i_mapping;
903 struct shmem_inode_info *info = SHMEM_I(inode);
904 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
905 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
906 unsigned int partial_start = lstart & (PAGE_SIZE - 1);
907 unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
908 struct pagevec pvec;
909 pgoff_t indices[PAGEVEC_SIZE];
910 long nr_swaps_freed = 0;
911 pgoff_t index;
912 int i;
913
914 if (lend == -1)
915 end = -1; /* unsigned, so actually very big */
916
917 pagevec_init(&pvec);
918 index = start;
919 while (index < end) {
920 pvec.nr = find_get_entries(mapping, index,
921 min(end - index, (pgoff_t)PAGEVEC_SIZE),
922 pvec.pages, indices);
923 if (!pvec.nr)
924 break;
925 for (i = 0; i < pagevec_count(&pvec); i++) {
926 struct page *page = pvec.pages[i];
927
928 index = indices[i];
929 if (index >= end)
930 break;
931
932 if (xa_is_value(page)) {
933 if (unfalloc)
934 continue;
935 nr_swaps_freed += !shmem_free_swap(mapping,
936 index, page);
937 continue;
938 }
939
940 VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
941
942 if (!trylock_page(page))
943 continue;
944
945 if ((!unfalloc || !PageUptodate(page)) &&
946 page_mapping(page) == mapping) {
947 VM_BUG_ON_PAGE(PageWriteback(page), page);
948 if (shmem_punch_compound(page, start, end))
949 truncate_inode_page(mapping, page);
950 }
951 unlock_page(page);
952 }
953 pagevec_remove_exceptionals(&pvec);
954 pagevec_release(&pvec);
955 cond_resched();
956 index++;
957 }
958
959 if (partial_start) {
960 struct page *page = NULL;
961 shmem_getpage(inode, start - 1, &page, SGP_READ);
962 if (page) {
963 unsigned int top = PAGE_SIZE;
964 if (start > end) {
965 top = partial_end;
966 partial_end = 0;
967 }
968 zero_user_segment(page, partial_start, top);
969 set_page_dirty(page);
970 unlock_page(page);
971 put_page(page);
972 }
973 }
974 if (partial_end) {
975 struct page *page = NULL;
976 shmem_getpage(inode, end, &page, SGP_READ);
977 if (page) {
978 zero_user_segment(page, 0, partial_end);
979 set_page_dirty(page);
980 unlock_page(page);
981 put_page(page);
982 }
983 }
984 if (start >= end)
985 return;
986
987 index = start;
988 while (index < end) {
989 cond_resched();
990
991 pvec.nr = find_get_entries(mapping, index,
992 min(end - index, (pgoff_t)PAGEVEC_SIZE),
993 pvec.pages, indices);
994 if (!pvec.nr) {
995 /* If all gone or hole-punch or unfalloc, we're done */
996 if (index == start || end != -1)
997 break;
998 /* But if truncating, restart to make sure all gone */
999 index = start;
1000 continue;
1001 }
1002 for (i = 0; i < pagevec_count(&pvec); i++) {
1003 struct page *page = pvec.pages[i];
1004
1005 index = indices[i];
1006 if (index >= end)
1007 break;
1008
1009 if (xa_is_value(page)) {
1010 if (unfalloc)
1011 continue;
1012 if (shmem_free_swap(mapping, index, page)) {
1013 /* Swap was replaced by page: retry */
1014 index--;
1015 break;
1016 }
1017 nr_swaps_freed++;
1018 continue;
1019 }
1020
1021 lock_page(page);
1022
1023 if (!unfalloc || !PageUptodate(page)) {
1024 if (page_mapping(page) != mapping) {
1025 /* Page was replaced by swap: retry */
1026 unlock_page(page);
1027 index--;
1028 break;
1029 }
1030 VM_BUG_ON_PAGE(PageWriteback(page), page);
1031 if (shmem_punch_compound(page, start, end))
1032 truncate_inode_page(mapping, page);
1033 else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1034 /* Wipe the page and don't get stuck */
1035 clear_highpage(page);
1036 flush_dcache_page(page);
1037 set_page_dirty(page);
1038 if (index <
1039 round_up(start, HPAGE_PMD_NR))
1040 start = index + 1;
1041 }
1042 }
1043 unlock_page(page);
1044 }
1045 pagevec_remove_exceptionals(&pvec);
1046 pagevec_release(&pvec);
1047 index++;
1048 }
1049
1050 spin_lock_irq(&info->lock);
1051 info->swapped -= nr_swaps_freed;
1052 shmem_recalc_inode(inode);
1053 spin_unlock_irq(&info->lock);
1054}
1055
1056void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1057{
1058 shmem_undo_range(inode, lstart, lend, false);
1059 inode->i_ctime = inode->i_mtime = current_time(inode);
1060}
1061EXPORT_SYMBOL_GPL(shmem_truncate_range);
1062
1063static int shmem_getattr(const struct path *path, struct kstat *stat,
1064 u32 request_mask, unsigned int query_flags)
1065{
1066 struct inode *inode = path->dentry->d_inode;
1067 struct shmem_inode_info *info = SHMEM_I(inode);
1068 struct shmem_sb_info *sb_info = SHMEM_SB(inode->i_sb);
1069
1070 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
1071 spin_lock_irq(&info->lock);
1072 shmem_recalc_inode(inode);
1073 spin_unlock_irq(&info->lock);
1074 }
1075 generic_fillattr(inode, stat);
1076
1077 if (is_huge_enabled(sb_info))
1078 stat->blksize = HPAGE_PMD_SIZE;
1079
1080 return 0;
1081}
1082
1083static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
1084{
1085 struct inode *inode = d_inode(dentry);
1086 struct shmem_inode_info *info = SHMEM_I(inode);
1087 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1088 int error;
1089
1090 error = setattr_prepare(dentry, attr);
1091 if (error)
1092 return error;
1093
1094 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1095 loff_t oldsize = inode->i_size;
1096 loff_t newsize = attr->ia_size;
1097
1098 /* protected by i_mutex */
1099 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1100 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1101 return -EPERM;
1102
1103 if (newsize != oldsize) {
1104 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1105 oldsize, newsize);
1106 if (error)
1107 return error;
1108 i_size_write(inode, newsize);
1109 inode->i_ctime = inode->i_mtime = current_time(inode);
1110 }
1111 if (newsize <= oldsize) {
1112 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1113 if (oldsize > holebegin)
1114 unmap_mapping_range(inode->i_mapping,
1115 holebegin, 0, 1);
1116 if (info->alloced)
1117 shmem_truncate_range(inode,
1118 newsize, (loff_t)-1);
1119 /* unmap again to remove racily COWed private pages */
1120 if (oldsize > holebegin)
1121 unmap_mapping_range(inode->i_mapping,
1122 holebegin, 0, 1);
1123
1124 /*
1125 * Part of the huge page can be beyond i_size: subject
1126 * to shrink under memory pressure.
1127 */
1128 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1129 spin_lock(&sbinfo->shrinklist_lock);
1130 /*
1131 * _careful to defend against unlocked access to
1132 * ->shrink_list in shmem_unused_huge_shrink()
1133 */
1134 if (list_empty_careful(&info->shrinklist)) {
1135 list_add_tail(&info->shrinklist,
1136 &sbinfo->shrinklist);
1137 sbinfo->shrinklist_len++;
1138 }
1139 spin_unlock(&sbinfo->shrinklist_lock);
1140 }
1141 }
1142 }
1143
1144 setattr_copy(inode, attr);
1145 if (attr->ia_valid & ATTR_MODE)
1146 error = posix_acl_chmod(inode, inode->i_mode);
1147 return error;
1148}
1149
1150static void shmem_evict_inode(struct inode *inode)
1151{
1152 struct shmem_inode_info *info = SHMEM_I(inode);
1153 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1154
1155 if (inode->i_mapping->a_ops == &shmem_aops) {
1156 shmem_unacct_size(info->flags, inode->i_size);
1157 inode->i_size = 0;
1158 shmem_truncate_range(inode, 0, (loff_t)-1);
1159 if (!list_empty(&info->shrinklist)) {
1160 spin_lock(&sbinfo->shrinklist_lock);
1161 if (!list_empty(&info->shrinklist)) {
1162 list_del_init(&info->shrinklist);
1163 sbinfo->shrinklist_len--;
1164 }
1165 spin_unlock(&sbinfo->shrinklist_lock);
1166 }
1167 while (!list_empty(&info->swaplist)) {
1168 /* Wait while shmem_unuse() is scanning this inode... */
1169 wait_var_event(&info->stop_eviction,
1170 !atomic_read(&info->stop_eviction));
1171 mutex_lock(&shmem_swaplist_mutex);
1172 /* ...but beware of the race if we peeked too early */
1173 if (!atomic_read(&info->stop_eviction))
1174 list_del_init(&info->swaplist);
1175 mutex_unlock(&shmem_swaplist_mutex);
1176 }
1177 }
1178
1179 simple_xattrs_free(&info->xattrs);
1180 WARN_ON(inode->i_blocks);
1181 shmem_free_inode(inode->i_sb);
1182 clear_inode(inode);
1183}
1184
1185extern struct swap_info_struct *swap_info[];
1186
1187static int shmem_find_swap_entries(struct address_space *mapping,
1188 pgoff_t start, unsigned int nr_entries,
1189 struct page **entries, pgoff_t *indices,
1190 unsigned int type, bool frontswap)
1191{
1192 XA_STATE(xas, &mapping->i_pages, start);
1193 struct page *page;
1194 swp_entry_t entry;
1195 unsigned int ret = 0;
1196
1197 if (!nr_entries)
1198 return 0;
1199
1200 rcu_read_lock();
1201 xas_for_each(&xas, page, ULONG_MAX) {
1202 if (xas_retry(&xas, page))
1203 continue;
1204
1205 if (!xa_is_value(page))
1206 continue;
1207
1208 entry = radix_to_swp_entry(page);
1209 if (swp_type(entry) != type)
1210 continue;
1211 if (frontswap &&
1212 !frontswap_test(swap_info[type], swp_offset(entry)))
1213 continue;
1214
1215 indices[ret] = xas.xa_index;
1216 entries[ret] = page;
1217
1218 if (need_resched()) {
1219 xas_pause(&xas);
1220 cond_resched_rcu();
1221 }
1222 if (++ret == nr_entries)
1223 break;
1224 }
1225 rcu_read_unlock();
1226
1227 return ret;
1228}
1229
1230/*
1231 * Move the swapped pages for an inode to page cache. Returns the count
1232 * of pages swapped in, or the error in case of failure.
1233 */
1234static int shmem_unuse_swap_entries(struct inode *inode, struct pagevec pvec,
1235 pgoff_t *indices)
1236{
1237 int i = 0;
1238 int ret = 0;
1239 int error = 0;
1240 struct address_space *mapping = inode->i_mapping;
1241
1242 for (i = 0; i < pvec.nr; i++) {
1243 struct page *page = pvec.pages[i];
1244
1245 if (!xa_is_value(page))
1246 continue;
1247 error = shmem_swapin_page(inode, indices[i],
1248 &page, SGP_CACHE,
1249 mapping_gfp_mask(mapping),
1250 NULL, NULL);
1251 if (error == 0) {
1252 unlock_page(page);
1253 put_page(page);
1254 ret++;
1255 }
1256 if (error == -ENOMEM)
1257 break;
1258 error = 0;
1259 }
1260 return error ? error : ret;
1261}
1262
1263/*
1264 * If swap found in inode, free it and move page from swapcache to filecache.
1265 */
1266static int shmem_unuse_inode(struct inode *inode, unsigned int type,
1267 bool frontswap, unsigned long *fs_pages_to_unuse)
1268{
1269 struct address_space *mapping = inode->i_mapping;
1270 pgoff_t start = 0;
1271 struct pagevec pvec;
1272 pgoff_t indices[PAGEVEC_SIZE];
1273 bool frontswap_partial = (frontswap && *fs_pages_to_unuse > 0);
1274 int ret = 0;
1275
1276 pagevec_init(&pvec);
1277 do {
1278 unsigned int nr_entries = PAGEVEC_SIZE;
1279
1280 if (frontswap_partial && *fs_pages_to_unuse < PAGEVEC_SIZE)
1281 nr_entries = *fs_pages_to_unuse;
1282
1283 pvec.nr = shmem_find_swap_entries(mapping, start, nr_entries,
1284 pvec.pages, indices,
1285 type, frontswap);
1286 if (pvec.nr == 0) {
1287 ret = 0;
1288 break;
1289 }
1290
1291 ret = shmem_unuse_swap_entries(inode, pvec, indices);
1292 if (ret < 0)
1293 break;
1294
1295 if (frontswap_partial) {
1296 *fs_pages_to_unuse -= ret;
1297 if (*fs_pages_to_unuse == 0) {
1298 ret = FRONTSWAP_PAGES_UNUSED;
1299 break;
1300 }
1301 }
1302
1303 start = indices[pvec.nr - 1];
1304 } while (true);
1305
1306 return ret;
1307}
1308
1309/*
1310 * Read all the shared memory data that resides in the swap
1311 * device 'type' back into memory, so the swap device can be
1312 * unused.
1313 */
1314int shmem_unuse(unsigned int type, bool frontswap,
1315 unsigned long *fs_pages_to_unuse)
1316{
1317 struct shmem_inode_info *info, *next;
1318 int error = 0;
1319
1320 if (list_empty(&shmem_swaplist))
1321 return 0;
1322
1323 mutex_lock(&shmem_swaplist_mutex);
1324 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1325 if (!info->swapped) {
1326 list_del_init(&info->swaplist);
1327 continue;
1328 }
1329 /*
1330 * Drop the swaplist mutex while searching the inode for swap;
1331 * but before doing so, make sure shmem_evict_inode() will not
1332 * remove placeholder inode from swaplist, nor let it be freed
1333 * (igrab() would protect from unlink, but not from unmount).
1334 */
1335 atomic_inc(&info->stop_eviction);
1336 mutex_unlock(&shmem_swaplist_mutex);
1337
1338 error = shmem_unuse_inode(&info->vfs_inode, type, frontswap,
1339 fs_pages_to_unuse);
1340 cond_resched();
1341
1342 mutex_lock(&shmem_swaplist_mutex);
1343 next = list_next_entry(info, swaplist);
1344 if (!info->swapped)
1345 list_del_init(&info->swaplist);
1346 if (atomic_dec_and_test(&info->stop_eviction))
1347 wake_up_var(&info->stop_eviction);
1348 if (error)
1349 break;
1350 }
1351 mutex_unlock(&shmem_swaplist_mutex);
1352
1353 return error;
1354}
1355
1356/*
1357 * Move the page from the page cache to the swap cache.
1358 */
1359static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1360{
1361 struct shmem_inode_info *info;
1362 struct address_space *mapping;
1363 struct inode *inode;
1364 swp_entry_t swap;
1365 pgoff_t index;
1366
1367 VM_BUG_ON_PAGE(PageCompound(page), page);
1368 BUG_ON(!PageLocked(page));
1369 mapping = page->mapping;
1370 index = page->index;
1371 inode = mapping->host;
1372 info = SHMEM_I(inode);
1373 if (info->flags & VM_LOCKED)
1374 goto redirty;
1375 if (!total_swap_pages)
1376 goto redirty;
1377
1378 /*
1379 * Our capabilities prevent regular writeback or sync from ever calling
1380 * shmem_writepage; but a stacking filesystem might use ->writepage of
1381 * its underlying filesystem, in which case tmpfs should write out to
1382 * swap only in response to memory pressure, and not for the writeback
1383 * threads or sync.
1384 */
1385 if (!wbc->for_reclaim) {
1386 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1387 goto redirty;
1388 }
1389
1390 /*
1391 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1392 * value into swapfile.c, the only way we can correctly account for a
1393 * fallocated page arriving here is now to initialize it and write it.
1394 *
1395 * That's okay for a page already fallocated earlier, but if we have
1396 * not yet completed the fallocation, then (a) we want to keep track
1397 * of this page in case we have to undo it, and (b) it may not be a
1398 * good idea to continue anyway, once we're pushing into swap. So
1399 * reactivate the page, and let shmem_fallocate() quit when too many.
1400 */
1401 if (!PageUptodate(page)) {
1402 if (inode->i_private) {
1403 struct shmem_falloc *shmem_falloc;
1404 spin_lock(&inode->i_lock);
1405 shmem_falloc = inode->i_private;
1406 if (shmem_falloc &&
1407 !shmem_falloc->waitq &&
1408 index >= shmem_falloc->start &&
1409 index < shmem_falloc->next)
1410 shmem_falloc->nr_unswapped++;
1411 else
1412 shmem_falloc = NULL;
1413 spin_unlock(&inode->i_lock);
1414 if (shmem_falloc)
1415 goto redirty;
1416 }
1417 clear_highpage(page);
1418 flush_dcache_page(page);
1419 SetPageUptodate(page);
1420 }
1421
1422 swap = get_swap_page(page);
1423 if (!swap.val)
1424 goto redirty;
1425
1426 /*
1427 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1428 * if it's not already there. Do it now before the page is
1429 * moved to swap cache, when its pagelock no longer protects
1430 * the inode from eviction. But don't unlock the mutex until
1431 * we've incremented swapped, because shmem_unuse_inode() will
1432 * prune a !swapped inode from the swaplist under this mutex.
1433 */
1434 mutex_lock(&shmem_swaplist_mutex);
1435 if (list_empty(&info->swaplist))
1436 list_add(&info->swaplist, &shmem_swaplist);
1437
1438 if (add_to_swap_cache(page, swap,
1439 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1440 NULL) == 0) {
1441 spin_lock_irq(&info->lock);
1442 shmem_recalc_inode(inode);
1443 info->swapped++;
1444 spin_unlock_irq(&info->lock);
1445
1446 swap_shmem_alloc(swap);
1447 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1448
1449 mutex_unlock(&shmem_swaplist_mutex);
1450 BUG_ON(page_mapped(page));
1451 swap_writepage(page, wbc);
1452 return 0;
1453 }
1454
1455 mutex_unlock(&shmem_swaplist_mutex);
1456 put_swap_page(page, swap);
1457redirty:
1458 set_page_dirty(page);
1459 if (wbc->for_reclaim)
1460 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1461 unlock_page(page);
1462 return 0;
1463}
1464
1465#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1466static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1467{
1468 char buffer[64];
1469
1470 if (!mpol || mpol->mode == MPOL_DEFAULT)
1471 return; /* show nothing */
1472
1473 mpol_to_str(buffer, sizeof(buffer), mpol);
1474
1475 seq_printf(seq, ",mpol=%s", buffer);
1476}
1477
1478static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1479{
1480 struct mempolicy *mpol = NULL;
1481 if (sbinfo->mpol) {
1482 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1483 mpol = sbinfo->mpol;
1484 mpol_get(mpol);
1485 spin_unlock(&sbinfo->stat_lock);
1486 }
1487 return mpol;
1488}
1489#else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1490static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1491{
1492}
1493static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1494{
1495 return NULL;
1496}
1497#endif /* CONFIG_NUMA && CONFIG_TMPFS */
1498#ifndef CONFIG_NUMA
1499#define vm_policy vm_private_data
1500#endif
1501
1502static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1503 struct shmem_inode_info *info, pgoff_t index)
1504{
1505 /* Create a pseudo vma that just contains the policy */
1506 vma_init(vma, NULL);
1507 /* Bias interleave by inode number to distribute better across nodes */
1508 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1509 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1510}
1511
1512static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1513{
1514 /* Drop reference taken by mpol_shared_policy_lookup() */
1515 mpol_cond_put(vma->vm_policy);
1516}
1517
1518static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1519 struct shmem_inode_info *info, pgoff_t index)
1520{
1521 struct vm_area_struct pvma;
1522 struct page *page;
1523 struct vm_fault vmf;
1524
1525 shmem_pseudo_vma_init(&pvma, info, index);
1526 vmf.vma = &pvma;
1527 vmf.address = 0;
1528 page = swap_cluster_readahead(swap, gfp, &vmf);
1529 shmem_pseudo_vma_destroy(&pvma);
1530
1531 return page;
1532}
1533
1534static struct page *shmem_alloc_hugepage(gfp_t gfp,
1535 struct shmem_inode_info *info, pgoff_t index)
1536{
1537 struct vm_area_struct pvma;
1538 struct address_space *mapping = info->vfs_inode.i_mapping;
1539 pgoff_t hindex;
1540 struct page *page;
1541
1542 hindex = round_down(index, HPAGE_PMD_NR);
1543 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1544 XA_PRESENT))
1545 return NULL;
1546
1547 shmem_pseudo_vma_init(&pvma, info, hindex);
1548 page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
1549 HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
1550 shmem_pseudo_vma_destroy(&pvma);
1551 if (page)
1552 prep_transhuge_page(page);
1553 else
1554 count_vm_event(THP_FILE_FALLBACK);
1555 return page;
1556}
1557
1558static struct page *shmem_alloc_page(gfp_t gfp,
1559 struct shmem_inode_info *info, pgoff_t index)
1560{
1561 struct vm_area_struct pvma;
1562 struct page *page;
1563
1564 shmem_pseudo_vma_init(&pvma, info, index);
1565 page = alloc_page_vma(gfp, &pvma, 0);
1566 shmem_pseudo_vma_destroy(&pvma);
1567
1568 return page;
1569}
1570
1571static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1572 struct inode *inode,
1573 pgoff_t index, bool huge)
1574{
1575 struct shmem_inode_info *info = SHMEM_I(inode);
1576 struct page *page;
1577 int nr;
1578 int err = -ENOSPC;
1579
1580 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1581 huge = false;
1582 nr = huge ? HPAGE_PMD_NR : 1;
1583
1584 if (!shmem_inode_acct_block(inode, nr))
1585 goto failed;
1586
1587 if (huge)
1588 page = shmem_alloc_hugepage(gfp, info, index);
1589 else
1590 page = shmem_alloc_page(gfp, info, index);
1591 if (page) {
1592 __SetPageLocked(page);
1593 __SetPageSwapBacked(page);
1594 return page;
1595 }
1596
1597 err = -ENOMEM;
1598 shmem_inode_unacct_blocks(inode, nr);
1599failed:
1600 return ERR_PTR(err);
1601}
1602
1603/*
1604 * When a page is moved from swapcache to shmem filecache (either by the
1605 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1606 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1607 * ignorance of the mapping it belongs to. If that mapping has special
1608 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1609 * we may need to copy to a suitable page before moving to filecache.
1610 *
1611 * In a future release, this may well be extended to respect cpuset and
1612 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1613 * but for now it is a simple matter of zone.
1614 */
1615static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1616{
1617 return page_zonenum(page) > gfp_zone(gfp);
1618}
1619
1620static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1621 struct shmem_inode_info *info, pgoff_t index)
1622{
1623 struct page *oldpage, *newpage;
1624 struct address_space *swap_mapping;
1625 swp_entry_t entry;
1626 pgoff_t swap_index;
1627 int error;
1628
1629 oldpage = *pagep;
1630 entry.val = page_private(oldpage);
1631 swap_index = swp_offset(entry);
1632 swap_mapping = page_mapping(oldpage);
1633
1634 /*
1635 * We have arrived here because our zones are constrained, so don't
1636 * limit chance of success by further cpuset and node constraints.
1637 */
1638 gfp &= ~GFP_CONSTRAINT_MASK;
1639 newpage = shmem_alloc_page(gfp, info, index);
1640 if (!newpage)
1641 return -ENOMEM;
1642
1643 get_page(newpage);
1644 copy_highpage(newpage, oldpage);
1645 flush_dcache_page(newpage);
1646
1647 __SetPageLocked(newpage);
1648 __SetPageSwapBacked(newpage);
1649 SetPageUptodate(newpage);
1650 set_page_private(newpage, entry.val);
1651 SetPageSwapCache(newpage);
1652
1653 /*
1654 * Our caller will very soon move newpage out of swapcache, but it's
1655 * a nice clean interface for us to replace oldpage by newpage there.
1656 */
1657 xa_lock_irq(&swap_mapping->i_pages);
1658 error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
1659 if (!error) {
1660 mem_cgroup_migrate(oldpage, newpage);
1661 __inc_lruvec_page_state(newpage, NR_FILE_PAGES);
1662 __dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
1663 }
1664 xa_unlock_irq(&swap_mapping->i_pages);
1665
1666 if (unlikely(error)) {
1667 /*
1668 * Is this possible? I think not, now that our callers check
1669 * both PageSwapCache and page_private after getting page lock;
1670 * but be defensive. Reverse old to newpage for clear and free.
1671 */
1672 oldpage = newpage;
1673 } else {
1674 lru_cache_add(newpage);
1675 *pagep = newpage;
1676 }
1677
1678 ClearPageSwapCache(oldpage);
1679 set_page_private(oldpage, 0);
1680
1681 unlock_page(oldpage);
1682 put_page(oldpage);
1683 put_page(oldpage);
1684 return error;
1685}
1686
1687/*
1688 * Swap in the page pointed to by *pagep.
1689 * Caller has to make sure that *pagep contains a valid swapped page.
1690 * Returns 0 and the page in pagep if success. On failure, returns the
1691 * error code and NULL in *pagep.
1692 */
1693static int shmem_swapin_page(struct inode *inode, pgoff_t index,
1694 struct page **pagep, enum sgp_type sgp,
1695 gfp_t gfp, struct vm_area_struct *vma,
1696 vm_fault_t *fault_type)
1697{
1698 struct address_space *mapping = inode->i_mapping;
1699 struct shmem_inode_info *info = SHMEM_I(inode);
1700 struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm;
1701 struct page *page;
1702 swp_entry_t swap;
1703 int error;
1704
1705 VM_BUG_ON(!*pagep || !xa_is_value(*pagep));
1706 swap = radix_to_swp_entry(*pagep);
1707 *pagep = NULL;
1708
1709 /* Look it up and read it in.. */
1710 page = lookup_swap_cache(swap, NULL, 0);
1711 if (!page) {
1712 /* Or update major stats only when swapin succeeds?? */
1713 if (fault_type) {
1714 *fault_type |= VM_FAULT_MAJOR;
1715 count_vm_event(PGMAJFAULT);
1716 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1717 }
1718 /* Here we actually start the io */
1719 page = shmem_swapin(swap, gfp, info, index);
1720 if (!page) {
1721 error = -ENOMEM;
1722 goto failed;
1723 }
1724 }
1725
1726 /* We have to do this with page locked to prevent races */
1727 lock_page(page);
1728 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1729 !shmem_confirm_swap(mapping, index, swap)) {
1730 error = -EEXIST;
1731 goto unlock;
1732 }
1733 if (!PageUptodate(page)) {
1734 error = -EIO;
1735 goto failed;
1736 }
1737 wait_on_page_writeback(page);
1738
1739 if (shmem_should_replace_page(page, gfp)) {
1740 error = shmem_replace_page(&page, gfp, info, index);
1741 if (error)
1742 goto failed;
1743 }
1744
1745 error = shmem_add_to_page_cache(page, mapping, index,
1746 swp_to_radix_entry(swap), gfp,
1747 charge_mm);
1748 if (error)
1749 goto failed;
1750
1751 spin_lock_irq(&info->lock);
1752 info->swapped--;
1753 shmem_recalc_inode(inode);
1754 spin_unlock_irq(&info->lock);
1755
1756 if (sgp == SGP_WRITE)
1757 mark_page_accessed(page);
1758
1759 delete_from_swap_cache(page);
1760 set_page_dirty(page);
1761 swap_free(swap);
1762
1763 *pagep = page;
1764 return 0;
1765failed:
1766 if (!shmem_confirm_swap(mapping, index, swap))
1767 error = -EEXIST;
1768unlock:
1769 if (page) {
1770 unlock_page(page);
1771 put_page(page);
1772 }
1773
1774 return error;
1775}
1776
1777/*
1778 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1779 *
1780 * If we allocate a new one we do not mark it dirty. That's up to the
1781 * vm. If we swap it in we mark it dirty since we also free the swap
1782 * entry since a page cannot live in both the swap and page cache.
1783 *
1784 * vmf and fault_type are only supplied by shmem_fault:
1785 * otherwise they are NULL.
1786 */
1787static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1788 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1789 struct vm_area_struct *vma, struct vm_fault *vmf,
1790 vm_fault_t *fault_type)
1791{
1792 struct address_space *mapping = inode->i_mapping;
1793 struct shmem_inode_info *info = SHMEM_I(inode);
1794 struct shmem_sb_info *sbinfo;
1795 struct mm_struct *charge_mm;
1796 struct page *page;
1797 enum sgp_type sgp_huge = sgp;
1798 pgoff_t hindex = index;
1799 int error;
1800 int once = 0;
1801 int alloced = 0;
1802
1803 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1804 return -EFBIG;
1805 if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
1806 sgp = SGP_CACHE;
1807repeat:
1808 if (sgp <= SGP_CACHE &&
1809 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1810 return -EINVAL;
1811 }
1812
1813 sbinfo = SHMEM_SB(inode->i_sb);
1814 charge_mm = vma ? vma->vm_mm : current->mm;
1815
1816 page = find_lock_entry(mapping, index);
1817 if (xa_is_value(page)) {
1818 error = shmem_swapin_page(inode, index, &page,
1819 sgp, gfp, vma, fault_type);
1820 if (error == -EEXIST)
1821 goto repeat;
1822
1823 *pagep = page;
1824 return error;
1825 }
1826
1827 if (page && sgp == SGP_WRITE)
1828 mark_page_accessed(page);
1829
1830 /* fallocated page? */
1831 if (page && !PageUptodate(page)) {
1832 if (sgp != SGP_READ)
1833 goto clear;
1834 unlock_page(page);
1835 put_page(page);
1836 page = NULL;
1837 }
1838 if (page || sgp == SGP_READ) {
1839 *pagep = page;
1840 return 0;
1841 }
1842
1843 /*
1844 * Fast cache lookup did not find it:
1845 * bring it back from swap or allocate.
1846 */
1847
1848 if (vma && userfaultfd_missing(vma)) {
1849 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1850 return 0;
1851 }
1852
1853 /* shmem_symlink() */
1854 if (mapping->a_ops != &shmem_aops)
1855 goto alloc_nohuge;
1856 if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
1857 goto alloc_nohuge;
1858 if (shmem_huge == SHMEM_HUGE_FORCE)
1859 goto alloc_huge;
1860 switch (sbinfo->huge) {
1861 case SHMEM_HUGE_NEVER:
1862 goto alloc_nohuge;
1863 case SHMEM_HUGE_WITHIN_SIZE: {
1864 loff_t i_size;
1865 pgoff_t off;
1866
1867 off = round_up(index, HPAGE_PMD_NR);
1868 i_size = round_up(i_size_read(inode), PAGE_SIZE);
1869 if (i_size >= HPAGE_PMD_SIZE &&
1870 i_size >> PAGE_SHIFT >= off)
1871 goto alloc_huge;
1872
1873 fallthrough;
1874 }
1875 case SHMEM_HUGE_ADVISE:
1876 if (sgp_huge == SGP_HUGE)
1877 goto alloc_huge;
1878 /* TODO: implement fadvise() hints */
1879 goto alloc_nohuge;
1880 }
1881
1882alloc_huge:
1883 page = shmem_alloc_and_acct_page(gfp, inode, index, true);
1884 if (IS_ERR(page)) {
1885alloc_nohuge:
1886 page = shmem_alloc_and_acct_page(gfp, inode,
1887 index, false);
1888 }
1889 if (IS_ERR(page)) {
1890 int retry = 5;
1891
1892 error = PTR_ERR(page);
1893 page = NULL;
1894 if (error != -ENOSPC)
1895 goto unlock;
1896 /*
1897 * Try to reclaim some space by splitting a huge page
1898 * beyond i_size on the filesystem.
1899 */
1900 while (retry--) {
1901 int ret;
1902
1903 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1904 if (ret == SHRINK_STOP)
1905 break;
1906 if (ret)
1907 goto alloc_nohuge;
1908 }
1909 goto unlock;
1910 }
1911
1912 if (PageTransHuge(page))
1913 hindex = round_down(index, HPAGE_PMD_NR);
1914 else
1915 hindex = index;
1916
1917 if (sgp == SGP_WRITE)
1918 __SetPageReferenced(page);
1919
1920 error = shmem_add_to_page_cache(page, mapping, hindex,
1921 NULL, gfp & GFP_RECLAIM_MASK,
1922 charge_mm);
1923 if (error)
1924 goto unacct;
1925 lru_cache_add(page);
1926
1927 spin_lock_irq(&info->lock);
1928 info->alloced += compound_nr(page);
1929 inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1930 shmem_recalc_inode(inode);
1931 spin_unlock_irq(&info->lock);
1932 alloced = true;
1933
1934 if (PageTransHuge(page) &&
1935 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1936 hindex + HPAGE_PMD_NR - 1) {
1937 /*
1938 * Part of the huge page is beyond i_size: subject
1939 * to shrink under memory pressure.
1940 */
1941 spin_lock(&sbinfo->shrinklist_lock);
1942 /*
1943 * _careful to defend against unlocked access to
1944 * ->shrink_list in shmem_unused_huge_shrink()
1945 */
1946 if (list_empty_careful(&info->shrinklist)) {
1947 list_add_tail(&info->shrinklist,
1948 &sbinfo->shrinklist);
1949 sbinfo->shrinklist_len++;
1950 }
1951 spin_unlock(&sbinfo->shrinklist_lock);
1952 }
1953
1954 /*
1955 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1956 */
1957 if (sgp == SGP_FALLOC)
1958 sgp = SGP_WRITE;
1959clear:
1960 /*
1961 * Let SGP_WRITE caller clear ends if write does not fill page;
1962 * but SGP_FALLOC on a page fallocated earlier must initialize
1963 * it now, lest undo on failure cancel our earlier guarantee.
1964 */
1965 if (sgp != SGP_WRITE && !PageUptodate(page)) {
1966 struct page *head = compound_head(page);
1967 int i;
1968
1969 for (i = 0; i < compound_nr(head); i++) {
1970 clear_highpage(head + i);
1971 flush_dcache_page(head + i);
1972 }
1973 SetPageUptodate(head);
1974 }
1975
1976 /* Perhaps the file has been truncated since we checked */
1977 if (sgp <= SGP_CACHE &&
1978 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1979 if (alloced) {
1980 ClearPageDirty(page);
1981 delete_from_page_cache(page);
1982 spin_lock_irq(&info->lock);
1983 shmem_recalc_inode(inode);
1984 spin_unlock_irq(&info->lock);
1985 }
1986 error = -EINVAL;
1987 goto unlock;
1988 }
1989 *pagep = page + index - hindex;
1990 return 0;
1991
1992 /*
1993 * Error recovery.
1994 */
1995unacct:
1996 shmem_inode_unacct_blocks(inode, compound_nr(page));
1997
1998 if (PageTransHuge(page)) {
1999 unlock_page(page);
2000 put_page(page);
2001 goto alloc_nohuge;
2002 }
2003unlock:
2004 if (page) {
2005 unlock_page(page);
2006 put_page(page);
2007 }
2008 if (error == -ENOSPC && !once++) {
2009 spin_lock_irq(&info->lock);
2010 shmem_recalc_inode(inode);
2011 spin_unlock_irq(&info->lock);
2012 goto repeat;
2013 }
2014 if (error == -EEXIST)
2015 goto repeat;
2016 return error;
2017}
2018
2019/*
2020 * This is like autoremove_wake_function, but it removes the wait queue
2021 * entry unconditionally - even if something else had already woken the
2022 * target.
2023 */
2024static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
2025{
2026 int ret = default_wake_function(wait, mode, sync, key);
2027 list_del_init(&wait->entry);
2028 return ret;
2029}
2030
2031static vm_fault_t shmem_fault(struct vm_fault *vmf)
2032{
2033 struct vm_area_struct *vma = vmf->vma;
2034 struct inode *inode = file_inode(vma->vm_file);
2035 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2036 enum sgp_type sgp;
2037 int err;
2038 vm_fault_t ret = VM_FAULT_LOCKED;
2039
2040 /*
2041 * Trinity finds that probing a hole which tmpfs is punching can
2042 * prevent the hole-punch from ever completing: which in turn
2043 * locks writers out with its hold on i_mutex. So refrain from
2044 * faulting pages into the hole while it's being punched. Although
2045 * shmem_undo_range() does remove the additions, it may be unable to
2046 * keep up, as each new page needs its own unmap_mapping_range() call,
2047 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2048 *
2049 * It does not matter if we sometimes reach this check just before the
2050 * hole-punch begins, so that one fault then races with the punch:
2051 * we just need to make racing faults a rare case.
2052 *
2053 * The implementation below would be much simpler if we just used a
2054 * standard mutex or completion: but we cannot take i_mutex in fault,
2055 * and bloating every shmem inode for this unlikely case would be sad.
2056 */
2057 if (unlikely(inode->i_private)) {
2058 struct shmem_falloc *shmem_falloc;
2059
2060 spin_lock(&inode->i_lock);
2061 shmem_falloc = inode->i_private;
2062 if (shmem_falloc &&
2063 shmem_falloc->waitq &&
2064 vmf->pgoff >= shmem_falloc->start &&
2065 vmf->pgoff < shmem_falloc->next) {
2066 struct file *fpin;
2067 wait_queue_head_t *shmem_falloc_waitq;
2068 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2069
2070 ret = VM_FAULT_NOPAGE;
2071 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2072 if (fpin)
2073 ret = VM_FAULT_RETRY;
2074
2075 shmem_falloc_waitq = shmem_falloc->waitq;
2076 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2077 TASK_UNINTERRUPTIBLE);
2078 spin_unlock(&inode->i_lock);
2079 schedule();
2080
2081 /*
2082 * shmem_falloc_waitq points into the shmem_fallocate()
2083 * stack of the hole-punching task: shmem_falloc_waitq
2084 * is usually invalid by the time we reach here, but
2085 * finish_wait() does not dereference it in that case;
2086 * though i_lock needed lest racing with wake_up_all().
2087 */
2088 spin_lock(&inode->i_lock);
2089 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2090 spin_unlock(&inode->i_lock);
2091
2092 if (fpin)
2093 fput(fpin);
2094 return ret;
2095 }
2096 spin_unlock(&inode->i_lock);
2097 }
2098
2099 sgp = SGP_CACHE;
2100
2101 if ((vma->vm_flags & VM_NOHUGEPAGE) ||
2102 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
2103 sgp = SGP_NOHUGE;
2104 else if (vma->vm_flags & VM_HUGEPAGE)
2105 sgp = SGP_HUGE;
2106
2107 err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
2108 gfp, vma, vmf, &ret);
2109 if (err)
2110 return vmf_error(err);
2111 return ret;
2112}
2113
2114unsigned long shmem_get_unmapped_area(struct file *file,
2115 unsigned long uaddr, unsigned long len,
2116 unsigned long pgoff, unsigned long flags)
2117{
2118 unsigned long (*get_area)(struct file *,
2119 unsigned long, unsigned long, unsigned long, unsigned long);
2120 unsigned long addr;
2121 unsigned long offset;
2122 unsigned long inflated_len;
2123 unsigned long inflated_addr;
2124 unsigned long inflated_offset;
2125
2126 if (len > TASK_SIZE)
2127 return -ENOMEM;
2128
2129 get_area = current->mm->get_unmapped_area;
2130 addr = get_area(file, uaddr, len, pgoff, flags);
2131
2132 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2133 return addr;
2134 if (IS_ERR_VALUE(addr))
2135 return addr;
2136 if (addr & ~PAGE_MASK)
2137 return addr;
2138 if (addr > TASK_SIZE - len)
2139 return addr;
2140
2141 if (shmem_huge == SHMEM_HUGE_DENY)
2142 return addr;
2143 if (len < HPAGE_PMD_SIZE)
2144 return addr;
2145 if (flags & MAP_FIXED)
2146 return addr;
2147 /*
2148 * Our priority is to support MAP_SHARED mapped hugely;
2149 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2150 * But if caller specified an address hint and we allocated area there
2151 * successfully, respect that as before.
2152 */
2153 if (uaddr == addr)
2154 return addr;
2155
2156 if (shmem_huge != SHMEM_HUGE_FORCE) {
2157 struct super_block *sb;
2158
2159 if (file) {
2160 VM_BUG_ON(file->f_op != &shmem_file_operations);
2161 sb = file_inode(file)->i_sb;
2162 } else {
2163 /*
2164 * Called directly from mm/mmap.c, or drivers/char/mem.c
2165 * for "/dev/zero", to create a shared anonymous object.
2166 */
2167 if (IS_ERR(shm_mnt))
2168 return addr;
2169 sb = shm_mnt->mnt_sb;
2170 }
2171 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2172 return addr;
2173 }
2174
2175 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2176 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2177 return addr;
2178 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2179 return addr;
2180
2181 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2182 if (inflated_len > TASK_SIZE)
2183 return addr;
2184 if (inflated_len < len)
2185 return addr;
2186
2187 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2188 if (IS_ERR_VALUE(inflated_addr))
2189 return addr;
2190 if (inflated_addr & ~PAGE_MASK)
2191 return addr;
2192
2193 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2194 inflated_addr += offset - inflated_offset;
2195 if (inflated_offset > offset)
2196 inflated_addr += HPAGE_PMD_SIZE;
2197
2198 if (inflated_addr > TASK_SIZE - len)
2199 return addr;
2200 return inflated_addr;
2201}
2202
2203#ifdef CONFIG_NUMA
2204static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2205{
2206 struct inode *inode = file_inode(vma->vm_file);
2207 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2208}
2209
2210static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2211 unsigned long addr)
2212{
2213 struct inode *inode = file_inode(vma->vm_file);
2214 pgoff_t index;
2215
2216 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2217 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2218}
2219#endif
2220
2221int shmem_lock(struct file *file, int lock, struct user_struct *user)
2222{
2223 struct inode *inode = file_inode(file);
2224 struct shmem_inode_info *info = SHMEM_I(inode);
2225 int retval = -ENOMEM;
2226
2227 /*
2228 * What serializes the accesses to info->flags?
2229 * ipc_lock_object() when called from shmctl_do_lock(),
2230 * no serialization needed when called from shm_destroy().
2231 */
2232 if (lock && !(info->flags & VM_LOCKED)) {
2233 if (!user_shm_lock(inode->i_size, user))
2234 goto out_nomem;
2235 info->flags |= VM_LOCKED;
2236 mapping_set_unevictable(file->f_mapping);
2237 }
2238 if (!lock && (info->flags & VM_LOCKED) && user) {
2239 user_shm_unlock(inode->i_size, user);
2240 info->flags &= ~VM_LOCKED;
2241 mapping_clear_unevictable(file->f_mapping);
2242 }
2243 retval = 0;
2244
2245out_nomem:
2246 return retval;
2247}
2248
2249static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2250{
2251 struct shmem_inode_info *info = SHMEM_I(file_inode(file));
2252
2253 if (info->seals & F_SEAL_FUTURE_WRITE) {
2254 /*
2255 * New PROT_WRITE and MAP_SHARED mmaps are not allowed when
2256 * "future write" seal active.
2257 */
2258 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
2259 return -EPERM;
2260
2261 /*
2262 * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as
2263 * MAP_SHARED and read-only, take care to not allow mprotect to
2264 * revert protections on such mappings. Do this only for shared
2265 * mappings. For private mappings, don't need to mask
2266 * VM_MAYWRITE as we still want them to be COW-writable.
2267 */
2268 if (vma->vm_flags & VM_SHARED)
2269 vma->vm_flags &= ~(VM_MAYWRITE);
2270 }
2271
2272 file_accessed(file);
2273 vma->vm_ops = &shmem_vm_ops;
2274 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
2275 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2276 (vma->vm_end & HPAGE_PMD_MASK)) {
2277 khugepaged_enter(vma, vma->vm_flags);
2278 }
2279 return 0;
2280}
2281
2282static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2283 umode_t mode, dev_t dev, unsigned long flags)
2284{
2285 struct inode *inode;
2286 struct shmem_inode_info *info;
2287 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2288 ino_t ino;
2289
2290 if (shmem_reserve_inode(sb, &ino))
2291 return NULL;
2292
2293 inode = new_inode(sb);
2294 if (inode) {
2295 inode->i_ino = ino;
2296 inode_init_owner(inode, dir, mode);
2297 inode->i_blocks = 0;
2298 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2299 inode->i_generation = prandom_u32();
2300 info = SHMEM_I(inode);
2301 memset(info, 0, (char *)inode - (char *)info);
2302 spin_lock_init(&info->lock);
2303 atomic_set(&info->stop_eviction, 0);
2304 info->seals = F_SEAL_SEAL;
2305 info->flags = flags & VM_NORESERVE;
2306 INIT_LIST_HEAD(&info->shrinklist);
2307 INIT_LIST_HEAD(&info->swaplist);
2308 simple_xattrs_init(&info->xattrs);
2309 cache_no_acl(inode);
2310
2311 switch (mode & S_IFMT) {
2312 default:
2313 inode->i_op = &shmem_special_inode_operations;
2314 init_special_inode(inode, mode, dev);
2315 break;
2316 case S_IFREG:
2317 inode->i_mapping->a_ops = &shmem_aops;
2318 inode->i_op = &shmem_inode_operations;
2319 inode->i_fop = &shmem_file_operations;
2320 mpol_shared_policy_init(&info->policy,
2321 shmem_get_sbmpol(sbinfo));
2322 break;
2323 case S_IFDIR:
2324 inc_nlink(inode);
2325 /* Some things misbehave if size == 0 on a directory */
2326 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2327 inode->i_op = &shmem_dir_inode_operations;
2328 inode->i_fop = &simple_dir_operations;
2329 break;
2330 case S_IFLNK:
2331 /*
2332 * Must not load anything in the rbtree,
2333 * mpol_free_shared_policy will not be called.
2334 */
2335 mpol_shared_policy_init(&info->policy, NULL);
2336 break;
2337 }
2338
2339 lockdep_annotate_inode_mutex_key(inode);
2340 } else
2341 shmem_free_inode(sb);
2342 return inode;
2343}
2344
2345bool shmem_mapping(struct address_space *mapping)
2346{
2347 return mapping->a_ops == &shmem_aops;
2348}
2349
2350static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2351 pmd_t *dst_pmd,
2352 struct vm_area_struct *dst_vma,
2353 unsigned long dst_addr,
2354 unsigned long src_addr,
2355 bool zeropage,
2356 struct page **pagep)
2357{
2358 struct inode *inode = file_inode(dst_vma->vm_file);
2359 struct shmem_inode_info *info = SHMEM_I(inode);
2360 struct address_space *mapping = inode->i_mapping;
2361 gfp_t gfp = mapping_gfp_mask(mapping);
2362 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2363 spinlock_t *ptl;
2364 void *page_kaddr;
2365 struct page *page;
2366 pte_t _dst_pte, *dst_pte;
2367 int ret;
2368 pgoff_t offset, max_off;
2369
2370 ret = -ENOMEM;
2371 if (!shmem_inode_acct_block(inode, 1))
2372 goto out;
2373
2374 if (!*pagep) {
2375 page = shmem_alloc_page(gfp, info, pgoff);
2376 if (!page)
2377 goto out_unacct_blocks;
2378
2379 if (!zeropage) { /* mcopy_atomic */
2380 page_kaddr = kmap_atomic(page);
2381 ret = copy_from_user(page_kaddr,
2382 (const void __user *)src_addr,
2383 PAGE_SIZE);
2384 kunmap_atomic(page_kaddr);
2385
2386 /* fallback to copy_from_user outside mmap_lock */
2387 if (unlikely(ret)) {
2388 *pagep = page;
2389 shmem_inode_unacct_blocks(inode, 1);
2390 /* don't free the page */
2391 return -ENOENT;
2392 }
2393 } else { /* mfill_zeropage_atomic */
2394 clear_highpage(page);
2395 }
2396 } else {
2397 page = *pagep;
2398 *pagep = NULL;
2399 }
2400
2401 VM_BUG_ON(PageLocked(page) || PageSwapBacked(page));
2402 __SetPageLocked(page);
2403 __SetPageSwapBacked(page);
2404 __SetPageUptodate(page);
2405
2406 ret = -EFAULT;
2407 offset = linear_page_index(dst_vma, dst_addr);
2408 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2409 if (unlikely(offset >= max_off))
2410 goto out_release;
2411
2412 ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL,
2413 gfp & GFP_RECLAIM_MASK, dst_mm);
2414 if (ret)
2415 goto out_release;
2416
2417 _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
2418 if (dst_vma->vm_flags & VM_WRITE)
2419 _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
2420 else {
2421 /*
2422 * We don't set the pte dirty if the vma has no
2423 * VM_WRITE permission, so mark the page dirty or it
2424 * could be freed from under us. We could do it
2425 * unconditionally before unlock_page(), but doing it
2426 * only if VM_WRITE is not set is faster.
2427 */
2428 set_page_dirty(page);
2429 }
2430
2431 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
2432
2433 ret = -EFAULT;
2434 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2435 if (unlikely(offset >= max_off))
2436 goto out_release_unlock;
2437
2438 ret = -EEXIST;
2439 if (!pte_none(*dst_pte))
2440 goto out_release_unlock;
2441
2442 lru_cache_add(page);
2443
2444 spin_lock_irq(&info->lock);
2445 info->alloced++;
2446 inode->i_blocks += BLOCKS_PER_PAGE;
2447 shmem_recalc_inode(inode);
2448 spin_unlock_irq(&info->lock);
2449
2450 inc_mm_counter(dst_mm, mm_counter_file(page));
2451 page_add_file_rmap(page, false);
2452 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
2453
2454 /* No need to invalidate - it was non-present before */
2455 update_mmu_cache(dst_vma, dst_addr, dst_pte);
2456 pte_unmap_unlock(dst_pte, ptl);
2457 unlock_page(page);
2458 ret = 0;
2459out:
2460 return ret;
2461out_release_unlock:
2462 pte_unmap_unlock(dst_pte, ptl);
2463 ClearPageDirty(page);
2464 delete_from_page_cache(page);
2465out_release:
2466 unlock_page(page);
2467 put_page(page);
2468out_unacct_blocks:
2469 shmem_inode_unacct_blocks(inode, 1);
2470 goto out;
2471}
2472
2473int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
2474 pmd_t *dst_pmd,
2475 struct vm_area_struct *dst_vma,
2476 unsigned long dst_addr,
2477 unsigned long src_addr,
2478 struct page **pagep)
2479{
2480 return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2481 dst_addr, src_addr, false, pagep);
2482}
2483
2484int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
2485 pmd_t *dst_pmd,
2486 struct vm_area_struct *dst_vma,
2487 unsigned long dst_addr)
2488{
2489 struct page *page = NULL;
2490
2491 return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2492 dst_addr, 0, true, &page);
2493}
2494
2495#ifdef CONFIG_TMPFS
2496static const struct inode_operations shmem_symlink_inode_operations;
2497static const struct inode_operations shmem_short_symlink_operations;
2498
2499#ifdef CONFIG_TMPFS_XATTR
2500static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2501#else
2502#define shmem_initxattrs NULL
2503#endif
2504
2505static int
2506shmem_write_begin(struct file *file, struct address_space *mapping,
2507 loff_t pos, unsigned len, unsigned flags,
2508 struct page **pagep, void **fsdata)
2509{
2510 struct inode *inode = mapping->host;
2511 struct shmem_inode_info *info = SHMEM_I(inode);
2512 pgoff_t index = pos >> PAGE_SHIFT;
2513
2514 /* i_mutex is held by caller */
2515 if (unlikely(info->seals & (F_SEAL_GROW |
2516 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2517 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2518 return -EPERM;
2519 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2520 return -EPERM;
2521 }
2522
2523 return shmem_getpage(inode, index, pagep, SGP_WRITE);
2524}
2525
2526static int
2527shmem_write_end(struct file *file, struct address_space *mapping,
2528 loff_t pos, unsigned len, unsigned copied,
2529 struct page *page, void *fsdata)
2530{
2531 struct inode *inode = mapping->host;
2532
2533 if (pos + copied > inode->i_size)
2534 i_size_write(inode, pos + copied);
2535
2536 if (!PageUptodate(page)) {
2537 struct page *head = compound_head(page);
2538 if (PageTransCompound(page)) {
2539 int i;
2540
2541 for (i = 0; i < HPAGE_PMD_NR; i++) {
2542 if (head + i == page)
2543 continue;
2544 clear_highpage(head + i);
2545 flush_dcache_page(head + i);
2546 }
2547 }
2548 if (copied < PAGE_SIZE) {
2549 unsigned from = pos & (PAGE_SIZE - 1);
2550 zero_user_segments(page, 0, from,
2551 from + copied, PAGE_SIZE);
2552 }
2553 SetPageUptodate(head);
2554 }
2555 set_page_dirty(page);
2556 unlock_page(page);
2557 put_page(page);
2558
2559 return copied;
2560}
2561
2562static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2563{
2564 struct file *file = iocb->ki_filp;
2565 struct inode *inode = file_inode(file);
2566 struct address_space *mapping = inode->i_mapping;
2567 pgoff_t index;
2568 unsigned long offset;
2569 enum sgp_type sgp = SGP_READ;
2570 int error = 0;
2571 ssize_t retval = 0;
2572 loff_t *ppos = &iocb->ki_pos;
2573
2574 /*
2575 * Might this read be for a stacking filesystem? Then when reading
2576 * holes of a sparse file, we actually need to allocate those pages,
2577 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2578 */
2579 if (!iter_is_iovec(to))
2580 sgp = SGP_CACHE;
2581
2582 index = *ppos >> PAGE_SHIFT;
2583 offset = *ppos & ~PAGE_MASK;
2584
2585 for (;;) {
2586 struct page *page = NULL;
2587 pgoff_t end_index;
2588 unsigned long nr, ret;
2589 loff_t i_size = i_size_read(inode);
2590
2591 end_index = i_size >> PAGE_SHIFT;
2592 if (index > end_index)
2593 break;
2594 if (index == end_index) {
2595 nr = i_size & ~PAGE_MASK;
2596 if (nr <= offset)
2597 break;
2598 }
2599
2600 error = shmem_getpage(inode, index, &page, sgp);
2601 if (error) {
2602 if (error == -EINVAL)
2603 error = 0;
2604 break;
2605 }
2606 if (page) {
2607 if (sgp == SGP_CACHE)
2608 set_page_dirty(page);
2609 unlock_page(page);
2610 }
2611
2612 /*
2613 * We must evaluate after, since reads (unlike writes)
2614 * are called without i_mutex protection against truncate
2615 */
2616 nr = PAGE_SIZE;
2617 i_size = i_size_read(inode);
2618 end_index = i_size >> PAGE_SHIFT;
2619 if (index == end_index) {
2620 nr = i_size & ~PAGE_MASK;
2621 if (nr <= offset) {
2622 if (page)
2623 put_page(page);
2624 break;
2625 }
2626 }
2627 nr -= offset;
2628
2629 if (page) {
2630 /*
2631 * If users can be writing to this page using arbitrary
2632 * virtual addresses, take care about potential aliasing
2633 * before reading the page on the kernel side.
2634 */
2635 if (mapping_writably_mapped(mapping))
2636 flush_dcache_page(page);
2637 /*
2638 * Mark the page accessed if we read the beginning.
2639 */
2640 if (!offset)
2641 mark_page_accessed(page);
2642 } else {
2643 page = ZERO_PAGE(0);
2644 get_page(page);
2645 }
2646
2647 /*
2648 * Ok, we have the page, and it's up-to-date, so
2649 * now we can copy it to user space...
2650 */
2651 ret = copy_page_to_iter(page, offset, nr, to);
2652 retval += ret;
2653 offset += ret;
2654 index += offset >> PAGE_SHIFT;
2655 offset &= ~PAGE_MASK;
2656
2657 put_page(page);
2658 if (!iov_iter_count(to))
2659 break;
2660 if (ret < nr) {
2661 error = -EFAULT;
2662 break;
2663 }
2664 cond_resched();
2665 }
2666
2667 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2668 file_accessed(file);
2669 return retval ? retval : error;
2670}
2671
2672/*
2673 * llseek SEEK_DATA or SEEK_HOLE through the page cache.
2674 */
2675static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
2676 pgoff_t index, pgoff_t end, int whence)
2677{
2678 struct page *page;
2679 struct pagevec pvec;
2680 pgoff_t indices[PAGEVEC_SIZE];
2681 bool done = false;
2682 int i;
2683
2684 pagevec_init(&pvec);
2685 pvec.nr = 1; /* start small: we may be there already */
2686 while (!done) {
2687 pvec.nr = find_get_entries(mapping, index,
2688 pvec.nr, pvec.pages, indices);
2689 if (!pvec.nr) {
2690 if (whence == SEEK_DATA)
2691 index = end;
2692 break;
2693 }
2694 for (i = 0; i < pvec.nr; i++, index++) {
2695 if (index < indices[i]) {
2696 if (whence == SEEK_HOLE) {
2697 done = true;
2698 break;
2699 }
2700 index = indices[i];
2701 }
2702 page = pvec.pages[i];
2703 if (page && !xa_is_value(page)) {
2704 if (!PageUptodate(page))
2705 page = NULL;
2706 }
2707 if (index >= end ||
2708 (page && whence == SEEK_DATA) ||
2709 (!page && whence == SEEK_HOLE)) {
2710 done = true;
2711 break;
2712 }
2713 }
2714 pagevec_remove_exceptionals(&pvec);
2715 pagevec_release(&pvec);
2716 pvec.nr = PAGEVEC_SIZE;
2717 cond_resched();
2718 }
2719 return index;
2720}
2721
2722static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2723{
2724 struct address_space *mapping = file->f_mapping;
2725 struct inode *inode = mapping->host;
2726 pgoff_t start, end;
2727 loff_t new_offset;
2728
2729 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2730 return generic_file_llseek_size(file, offset, whence,
2731 MAX_LFS_FILESIZE, i_size_read(inode));
2732 inode_lock(inode);
2733 /* We're holding i_mutex so we can access i_size directly */
2734
2735 if (offset < 0 || offset >= inode->i_size)
2736 offset = -ENXIO;
2737 else {
2738 start = offset >> PAGE_SHIFT;
2739 end = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2740 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
2741 new_offset <<= PAGE_SHIFT;
2742 if (new_offset > offset) {
2743 if (new_offset < inode->i_size)
2744 offset = new_offset;
2745 else if (whence == SEEK_DATA)
2746 offset = -ENXIO;
2747 else
2748 offset = inode->i_size;
2749 }
2750 }
2751
2752 if (offset >= 0)
2753 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2754 inode_unlock(inode);
2755 return offset;
2756}
2757
2758static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2759 loff_t len)
2760{
2761 struct inode *inode = file_inode(file);
2762 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2763 struct shmem_inode_info *info = SHMEM_I(inode);
2764 struct shmem_falloc shmem_falloc;
2765 pgoff_t start, index, end;
2766 int error;
2767
2768 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2769 return -EOPNOTSUPP;
2770
2771 inode_lock(inode);
2772
2773 if (mode & FALLOC_FL_PUNCH_HOLE) {
2774 struct address_space *mapping = file->f_mapping;
2775 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2776 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2777 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2778
2779 /* protected by i_mutex */
2780 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
2781 error = -EPERM;
2782 goto out;
2783 }
2784
2785 shmem_falloc.waitq = &shmem_falloc_waitq;
2786 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
2787 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2788 spin_lock(&inode->i_lock);
2789 inode->i_private = &shmem_falloc;
2790 spin_unlock(&inode->i_lock);
2791
2792 if ((u64)unmap_end > (u64)unmap_start)
2793 unmap_mapping_range(mapping, unmap_start,
2794 1 + unmap_end - unmap_start, 0);
2795 shmem_truncate_range(inode, offset, offset + len - 1);
2796 /* No need to unmap again: hole-punching leaves COWed pages */
2797
2798 spin_lock(&inode->i_lock);
2799 inode->i_private = NULL;
2800 wake_up_all(&shmem_falloc_waitq);
2801 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2802 spin_unlock(&inode->i_lock);
2803 error = 0;
2804 goto out;
2805 }
2806
2807 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2808 error = inode_newsize_ok(inode, offset + len);
2809 if (error)
2810 goto out;
2811
2812 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2813 error = -EPERM;
2814 goto out;
2815 }
2816
2817 start = offset >> PAGE_SHIFT;
2818 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2819 /* Try to avoid a swapstorm if len is impossible to satisfy */
2820 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2821 error = -ENOSPC;
2822 goto out;
2823 }
2824
2825 shmem_falloc.waitq = NULL;
2826 shmem_falloc.start = start;
2827 shmem_falloc.next = start;
2828 shmem_falloc.nr_falloced = 0;
2829 shmem_falloc.nr_unswapped = 0;
2830 spin_lock(&inode->i_lock);
2831 inode->i_private = &shmem_falloc;
2832 spin_unlock(&inode->i_lock);
2833
2834 for (index = start; index < end; index++) {
2835 struct page *page;
2836
2837 /*
2838 * Good, the fallocate(2) manpage permits EINTR: we may have
2839 * been interrupted because we are using up too much memory.
2840 */
2841 if (signal_pending(current))
2842 error = -EINTR;
2843 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2844 error = -ENOMEM;
2845 else
2846 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2847 if (error) {
2848 /* Remove the !PageUptodate pages we added */
2849 if (index > start) {
2850 shmem_undo_range(inode,
2851 (loff_t)start << PAGE_SHIFT,
2852 ((loff_t)index << PAGE_SHIFT) - 1, true);
2853 }
2854 goto undone;
2855 }
2856
2857 /*
2858 * Inform shmem_writepage() how far we have reached.
2859 * No need for lock or barrier: we have the page lock.
2860 */
2861 shmem_falloc.next++;
2862 if (!PageUptodate(page))
2863 shmem_falloc.nr_falloced++;
2864
2865 /*
2866 * If !PageUptodate, leave it that way so that freeable pages
2867 * can be recognized if we need to rollback on error later.
2868 * But set_page_dirty so that memory pressure will swap rather
2869 * than free the pages we are allocating (and SGP_CACHE pages
2870 * might still be clean: we now need to mark those dirty too).
2871 */
2872 set_page_dirty(page);
2873 unlock_page(page);
2874 put_page(page);
2875 cond_resched();
2876 }
2877
2878 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2879 i_size_write(inode, offset + len);
2880 inode->i_ctime = current_time(inode);
2881undone:
2882 spin_lock(&inode->i_lock);
2883 inode->i_private = NULL;
2884 spin_unlock(&inode->i_lock);
2885out:
2886 inode_unlock(inode);
2887 return error;
2888}
2889
2890static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2891{
2892 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2893
2894 buf->f_type = TMPFS_MAGIC;
2895 buf->f_bsize = PAGE_SIZE;
2896 buf->f_namelen = NAME_MAX;
2897 if (sbinfo->max_blocks) {
2898 buf->f_blocks = sbinfo->max_blocks;
2899 buf->f_bavail =
2900 buf->f_bfree = sbinfo->max_blocks -
2901 percpu_counter_sum(&sbinfo->used_blocks);
2902 }
2903 if (sbinfo->max_inodes) {
2904 buf->f_files = sbinfo->max_inodes;
2905 buf->f_ffree = sbinfo->free_inodes;
2906 }
2907 /* else leave those fields 0 like simple_statfs */
2908 return 0;
2909}
2910
2911/*
2912 * File creation. Allocate an inode, and we're done..
2913 */
2914static int
2915shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
2916{
2917 struct inode *inode;
2918 int error = -ENOSPC;
2919
2920 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2921 if (inode) {
2922 error = simple_acl_create(dir, inode);
2923 if (error)
2924 goto out_iput;
2925 error = security_inode_init_security(inode, dir,
2926 &dentry->d_name,
2927 shmem_initxattrs, NULL);
2928 if (error && error != -EOPNOTSUPP)
2929 goto out_iput;
2930
2931 error = 0;
2932 dir->i_size += BOGO_DIRENT_SIZE;
2933 dir->i_ctime = dir->i_mtime = current_time(dir);
2934 d_instantiate(dentry, inode);
2935 dget(dentry); /* Extra count - pin the dentry in core */
2936 }
2937 return error;
2938out_iput:
2939 iput(inode);
2940 return error;
2941}
2942
2943static int
2944shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
2945{
2946 struct inode *inode;
2947 int error = -ENOSPC;
2948
2949 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2950 if (inode) {
2951 error = security_inode_init_security(inode, dir,
2952 NULL,
2953 shmem_initxattrs, NULL);
2954 if (error && error != -EOPNOTSUPP)
2955 goto out_iput;
2956 error = simple_acl_create(dir, inode);
2957 if (error)
2958 goto out_iput;
2959 d_tmpfile(dentry, inode);
2960 }
2961 return error;
2962out_iput:
2963 iput(inode);
2964 return error;
2965}
2966
2967static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
2968{
2969 int error;
2970
2971 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
2972 return error;
2973 inc_nlink(dir);
2974 return 0;
2975}
2976
2977static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
2978 bool excl)
2979{
2980 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
2981}
2982
2983/*
2984 * Link a file..
2985 */
2986static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2987{
2988 struct inode *inode = d_inode(old_dentry);
2989 int ret = 0;
2990
2991 /*
2992 * No ordinary (disk based) filesystem counts links as inodes;
2993 * but each new link needs a new dentry, pinning lowmem, and
2994 * tmpfs dentries cannot be pruned until they are unlinked.
2995 * But if an O_TMPFILE file is linked into the tmpfs, the
2996 * first link must skip that, to get the accounting right.
2997 */
2998 if (inode->i_nlink) {
2999 ret = shmem_reserve_inode(inode->i_sb, NULL);
3000 if (ret)
3001 goto out;
3002 }
3003
3004 dir->i_size += BOGO_DIRENT_SIZE;
3005 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
3006 inc_nlink(inode);
3007 ihold(inode); /* New dentry reference */
3008 dget(dentry); /* Extra pinning count for the created dentry */
3009 d_instantiate(dentry, inode);
3010out:
3011 return ret;
3012}
3013
3014static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3015{
3016 struct inode *inode = d_inode(dentry);
3017
3018 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3019 shmem_free_inode(inode->i_sb);
3020
3021 dir->i_size -= BOGO_DIRENT_SIZE;
3022 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
3023 drop_nlink(inode);
3024 dput(dentry); /* Undo the count from "create" - this does all the work */
3025 return 0;
3026}
3027
3028static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3029{
3030 if (!simple_empty(dentry))
3031 return -ENOTEMPTY;
3032
3033 drop_nlink(d_inode(dentry));
3034 drop_nlink(dir);
3035 return shmem_unlink(dir, dentry);
3036}
3037
3038static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
3039{
3040 bool old_is_dir = d_is_dir(old_dentry);
3041 bool new_is_dir = d_is_dir(new_dentry);
3042
3043 if (old_dir != new_dir && old_is_dir != new_is_dir) {
3044 if (old_is_dir) {
3045 drop_nlink(old_dir);
3046 inc_nlink(new_dir);
3047 } else {
3048 drop_nlink(new_dir);
3049 inc_nlink(old_dir);
3050 }
3051 }
3052 old_dir->i_ctime = old_dir->i_mtime =
3053 new_dir->i_ctime = new_dir->i_mtime =
3054 d_inode(old_dentry)->i_ctime =
3055 d_inode(new_dentry)->i_ctime = current_time(old_dir);
3056
3057 return 0;
3058}
3059
3060static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
3061{
3062 struct dentry *whiteout;
3063 int error;
3064
3065 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3066 if (!whiteout)
3067 return -ENOMEM;
3068
3069 error = shmem_mknod(old_dir, whiteout,
3070 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3071 dput(whiteout);
3072 if (error)
3073 return error;
3074
3075 /*
3076 * Cheat and hash the whiteout while the old dentry is still in
3077 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3078 *
3079 * d_lookup() will consistently find one of them at this point,
3080 * not sure which one, but that isn't even important.
3081 */
3082 d_rehash(whiteout);
3083 return 0;
3084}
3085
3086/*
3087 * The VFS layer already does all the dentry stuff for rename,
3088 * we just have to decrement the usage count for the target if
3089 * it exists so that the VFS layer correctly free's it when it
3090 * gets overwritten.
3091 */
3092static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
3093{
3094 struct inode *inode = d_inode(old_dentry);
3095 int they_are_dirs = S_ISDIR(inode->i_mode);
3096
3097 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3098 return -EINVAL;
3099
3100 if (flags & RENAME_EXCHANGE)
3101 return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
3102
3103 if (!simple_empty(new_dentry))
3104 return -ENOTEMPTY;
3105
3106 if (flags & RENAME_WHITEOUT) {
3107 int error;
3108
3109 error = shmem_whiteout(old_dir, old_dentry);
3110 if (error)
3111 return error;
3112 }
3113
3114 if (d_really_is_positive(new_dentry)) {
3115 (void) shmem_unlink(new_dir, new_dentry);
3116 if (they_are_dirs) {
3117 drop_nlink(d_inode(new_dentry));
3118 drop_nlink(old_dir);
3119 }
3120 } else if (they_are_dirs) {
3121 drop_nlink(old_dir);
3122 inc_nlink(new_dir);
3123 }
3124
3125 old_dir->i_size -= BOGO_DIRENT_SIZE;
3126 new_dir->i_size += BOGO_DIRENT_SIZE;
3127 old_dir->i_ctime = old_dir->i_mtime =
3128 new_dir->i_ctime = new_dir->i_mtime =
3129 inode->i_ctime = current_time(old_dir);
3130 return 0;
3131}
3132
3133static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
3134{
3135 int error;
3136 int len;
3137 struct inode *inode;
3138 struct page *page;
3139
3140 len = strlen(symname) + 1;
3141 if (len > PAGE_SIZE)
3142 return -ENAMETOOLONG;
3143
3144 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0,
3145 VM_NORESERVE);
3146 if (!inode)
3147 return -ENOSPC;
3148
3149 error = security_inode_init_security(inode, dir, &dentry->d_name,
3150 shmem_initxattrs, NULL);
3151 if (error && error != -EOPNOTSUPP) {
3152 iput(inode);
3153 return error;
3154 }
3155
3156 inode->i_size = len-1;
3157 if (len <= SHORT_SYMLINK_LEN) {
3158 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3159 if (!inode->i_link) {
3160 iput(inode);
3161 return -ENOMEM;
3162 }
3163 inode->i_op = &shmem_short_symlink_operations;
3164 } else {
3165 inode_nohighmem(inode);
3166 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3167 if (error) {
3168 iput(inode);
3169 return error;
3170 }
3171 inode->i_mapping->a_ops = &shmem_aops;
3172 inode->i_op = &shmem_symlink_inode_operations;
3173 memcpy(page_address(page), symname, len);
3174 SetPageUptodate(page);
3175 set_page_dirty(page);
3176 unlock_page(page);
3177 put_page(page);
3178 }
3179 dir->i_size += BOGO_DIRENT_SIZE;
3180 dir->i_ctime = dir->i_mtime = current_time(dir);
3181 d_instantiate(dentry, inode);
3182 dget(dentry);
3183 return 0;
3184}
3185
3186static void shmem_put_link(void *arg)
3187{
3188 mark_page_accessed(arg);
3189 put_page(arg);
3190}
3191
3192static const char *shmem_get_link(struct dentry *dentry,
3193 struct inode *inode,
3194 struct delayed_call *done)
3195{
3196 struct page *page = NULL;
3197 int error;
3198 if (!dentry) {
3199 page = find_get_page(inode->i_mapping, 0);
3200 if (!page)
3201 return ERR_PTR(-ECHILD);
3202 if (!PageUptodate(page)) {
3203 put_page(page);
3204 return ERR_PTR(-ECHILD);
3205 }
3206 } else {
3207 error = shmem_getpage(inode, 0, &page, SGP_READ);
3208 if (error)
3209 return ERR_PTR(error);
3210 unlock_page(page);
3211 }
3212 set_delayed_call(done, shmem_put_link, page);
3213 return page_address(page);
3214}
3215
3216#ifdef CONFIG_TMPFS_XATTR
3217/*
3218 * Superblocks without xattr inode operations may get some security.* xattr
3219 * support from the LSM "for free". As soon as we have any other xattrs
3220 * like ACLs, we also need to implement the security.* handlers at
3221 * filesystem level, though.
3222 */
3223
3224/*
3225 * Callback for security_inode_init_security() for acquiring xattrs.
3226 */
3227static int shmem_initxattrs(struct inode *inode,
3228 const struct xattr *xattr_array,
3229 void *fs_info)
3230{
3231 struct shmem_inode_info *info = SHMEM_I(inode);
3232 const struct xattr *xattr;
3233 struct simple_xattr *new_xattr;
3234 size_t len;
3235
3236 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3237 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3238 if (!new_xattr)
3239 return -ENOMEM;
3240
3241 len = strlen(xattr->name) + 1;
3242 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3243 GFP_KERNEL);
3244 if (!new_xattr->name) {
3245 kvfree(new_xattr);
3246 return -ENOMEM;
3247 }
3248
3249 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3250 XATTR_SECURITY_PREFIX_LEN);
3251 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3252 xattr->name, len);
3253
3254 simple_xattr_list_add(&info->xattrs, new_xattr);
3255 }
3256
3257 return 0;
3258}
3259
3260static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3261 struct dentry *unused, struct inode *inode,
3262 const char *name, void *buffer, size_t size)
3263{
3264 struct shmem_inode_info *info = SHMEM_I(inode);
3265
3266 name = xattr_full_name(handler, name);
3267 return simple_xattr_get(&info->xattrs, name, buffer, size);
3268}
3269
3270static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3271 struct dentry *unused, struct inode *inode,
3272 const char *name, const void *value,
3273 size_t size, int flags)
3274{
3275 struct shmem_inode_info *info = SHMEM_I(inode);
3276
3277 name = xattr_full_name(handler, name);
3278 return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
3279}
3280
3281static const struct xattr_handler shmem_security_xattr_handler = {
3282 .prefix = XATTR_SECURITY_PREFIX,
3283 .get = shmem_xattr_handler_get,
3284 .set = shmem_xattr_handler_set,
3285};
3286
3287static const struct xattr_handler shmem_trusted_xattr_handler = {
3288 .prefix = XATTR_TRUSTED_PREFIX,
3289 .get = shmem_xattr_handler_get,
3290 .set = shmem_xattr_handler_set,
3291};
3292
3293static const struct xattr_handler *shmem_xattr_handlers[] = {
3294#ifdef CONFIG_TMPFS_POSIX_ACL
3295 &posix_acl_access_xattr_handler,
3296 &posix_acl_default_xattr_handler,
3297#endif
3298 &shmem_security_xattr_handler,
3299 &shmem_trusted_xattr_handler,
3300 NULL
3301};
3302
3303static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3304{
3305 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3306 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3307}
3308#endif /* CONFIG_TMPFS_XATTR */
3309
3310static const struct inode_operations shmem_short_symlink_operations = {
3311 .get_link = simple_get_link,
3312#ifdef CONFIG_TMPFS_XATTR
3313 .listxattr = shmem_listxattr,
3314#endif
3315};
3316
3317static const struct inode_operations shmem_symlink_inode_operations = {
3318 .get_link = shmem_get_link,
3319#ifdef CONFIG_TMPFS_XATTR
3320 .listxattr = shmem_listxattr,
3321#endif
3322};
3323
3324static struct dentry *shmem_get_parent(struct dentry *child)
3325{
3326 return ERR_PTR(-ESTALE);
3327}
3328
3329static int shmem_match(struct inode *ino, void *vfh)
3330{
3331 __u32 *fh = vfh;
3332 __u64 inum = fh[2];
3333 inum = (inum << 32) | fh[1];
3334 return ino->i_ino == inum && fh[0] == ino->i_generation;
3335}
3336
3337/* Find any alias of inode, but prefer a hashed alias */
3338static struct dentry *shmem_find_alias(struct inode *inode)
3339{
3340 struct dentry *alias = d_find_alias(inode);
3341
3342 return alias ?: d_find_any_alias(inode);
3343}
3344
3345
3346static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3347 struct fid *fid, int fh_len, int fh_type)
3348{
3349 struct inode *inode;
3350 struct dentry *dentry = NULL;
3351 u64 inum;
3352
3353 if (fh_len < 3)
3354 return NULL;
3355
3356 inum = fid->raw[2];
3357 inum = (inum << 32) | fid->raw[1];
3358
3359 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3360 shmem_match, fid->raw);
3361 if (inode) {
3362 dentry = shmem_find_alias(inode);
3363 iput(inode);
3364 }
3365
3366 return dentry;
3367}
3368
3369static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3370 struct inode *parent)
3371{
3372 if (*len < 3) {
3373 *len = 3;
3374 return FILEID_INVALID;
3375 }
3376
3377 if (inode_unhashed(inode)) {
3378 /* Unfortunately insert_inode_hash is not idempotent,
3379 * so as we hash inodes here rather than at creation
3380 * time, we need a lock to ensure we only try
3381 * to do it once
3382 */
3383 static DEFINE_SPINLOCK(lock);
3384 spin_lock(&lock);
3385 if (inode_unhashed(inode))
3386 __insert_inode_hash(inode,
3387 inode->i_ino + inode->i_generation);
3388 spin_unlock(&lock);
3389 }
3390
3391 fh[0] = inode->i_generation;
3392 fh[1] = inode->i_ino;
3393 fh[2] = ((__u64)inode->i_ino) >> 32;
3394
3395 *len = 3;
3396 return 1;
3397}
3398
3399static const struct export_operations shmem_export_ops = {
3400 .get_parent = shmem_get_parent,
3401 .encode_fh = shmem_encode_fh,
3402 .fh_to_dentry = shmem_fh_to_dentry,
3403};
3404
3405enum shmem_param {
3406 Opt_gid,
3407 Opt_huge,
3408 Opt_mode,
3409 Opt_mpol,
3410 Opt_nr_blocks,
3411 Opt_nr_inodes,
3412 Opt_size,
3413 Opt_uid,
3414 Opt_inode32,
3415 Opt_inode64,
3416};
3417
3418static const struct constant_table shmem_param_enums_huge[] = {
3419 {"never", SHMEM_HUGE_NEVER },
3420 {"always", SHMEM_HUGE_ALWAYS },
3421 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3422 {"advise", SHMEM_HUGE_ADVISE },
3423 {}
3424};
3425
3426const struct fs_parameter_spec shmem_fs_parameters[] = {
3427 fsparam_u32 ("gid", Opt_gid),
3428 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3429 fsparam_u32oct("mode", Opt_mode),
3430 fsparam_string("mpol", Opt_mpol),
3431 fsparam_string("nr_blocks", Opt_nr_blocks),
3432 fsparam_string("nr_inodes", Opt_nr_inodes),
3433 fsparam_string("size", Opt_size),
3434 fsparam_u32 ("uid", Opt_uid),
3435 fsparam_flag ("inode32", Opt_inode32),
3436 fsparam_flag ("inode64", Opt_inode64),
3437 {}
3438};
3439
3440static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3441{
3442 struct shmem_options *ctx = fc->fs_private;
3443 struct fs_parse_result result;
3444 unsigned long long size;
3445 char *rest;
3446 int opt;
3447
3448 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3449 if (opt < 0)
3450 return opt;
3451
3452 switch (opt) {
3453 case Opt_size:
3454 size = memparse(param->string, &rest);
3455 if (*rest == '%') {
3456 size <<= PAGE_SHIFT;
3457 size *= totalram_pages();
3458 do_div(size, 100);
3459 rest++;
3460 }
3461 if (*rest)
3462 goto bad_value;
3463 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3464 ctx->seen |= SHMEM_SEEN_BLOCKS;
3465 break;
3466 case Opt_nr_blocks:
3467 ctx->blocks = memparse(param->string, &rest);
3468 if (*rest)
3469 goto bad_value;
3470 ctx->seen |= SHMEM_SEEN_BLOCKS;
3471 break;
3472 case Opt_nr_inodes:
3473 ctx->inodes = memparse(param->string, &rest);
3474 if (*rest)
3475 goto bad_value;
3476 ctx->seen |= SHMEM_SEEN_INODES;
3477 break;
3478 case Opt_mode:
3479 ctx->mode = result.uint_32 & 07777;
3480 break;
3481 case Opt_uid:
3482 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
3483 if (!uid_valid(ctx->uid))
3484 goto bad_value;
3485 break;
3486 case Opt_gid:
3487 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
3488 if (!gid_valid(ctx->gid))
3489 goto bad_value;
3490 break;
3491 case Opt_huge:
3492 ctx->huge = result.uint_32;
3493 if (ctx->huge != SHMEM_HUGE_NEVER &&
3494 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
3495 has_transparent_hugepage()))
3496 goto unsupported_parameter;
3497 ctx->seen |= SHMEM_SEEN_HUGE;
3498 break;
3499 case Opt_mpol:
3500 if (IS_ENABLED(CONFIG_NUMA)) {
3501 mpol_put(ctx->mpol);
3502 ctx->mpol = NULL;
3503 if (mpol_parse_str(param->string, &ctx->mpol))
3504 goto bad_value;
3505 break;
3506 }
3507 goto unsupported_parameter;
3508 case Opt_inode32:
3509 ctx->full_inums = false;
3510 ctx->seen |= SHMEM_SEEN_INUMS;
3511 break;
3512 case Opt_inode64:
3513 if (sizeof(ino_t) < 8) {
3514 return invalfc(fc,
3515 "Cannot use inode64 with <64bit inums in kernel\n");
3516 }
3517 ctx->full_inums = true;
3518 ctx->seen |= SHMEM_SEEN_INUMS;
3519 break;
3520 }
3521 return 0;
3522
3523unsupported_parameter:
3524 return invalfc(fc, "Unsupported parameter '%s'", param->key);
3525bad_value:
3526 return invalfc(fc, "Bad value for '%s'", param->key);
3527}
3528
3529static int shmem_parse_options(struct fs_context *fc, void *data)
3530{
3531 char *options = data;
3532
3533 if (options) {
3534 int err = security_sb_eat_lsm_opts(options, &fc->security);
3535 if (err)
3536 return err;
3537 }
3538
3539 while (options != NULL) {
3540 char *this_char = options;
3541 for (;;) {
3542 /*
3543 * NUL-terminate this option: unfortunately,
3544 * mount options form a comma-separated list,
3545 * but mpol's nodelist may also contain commas.
3546 */
3547 options = strchr(options, ',');
3548 if (options == NULL)
3549 break;
3550 options++;
3551 if (!isdigit(*options)) {
3552 options[-1] = '\0';
3553 break;
3554 }
3555 }
3556 if (*this_char) {
3557 char *value = strchr(this_char,'=');
3558 size_t len = 0;
3559 int err;
3560
3561 if (value) {
3562 *value++ = '\0';
3563 len = strlen(value);
3564 }
3565 err = vfs_parse_fs_string(fc, this_char, value, len);
3566 if (err < 0)
3567 return err;
3568 }
3569 }
3570 return 0;
3571}
3572
3573/*
3574 * Reconfigure a shmem filesystem.
3575 *
3576 * Note that we disallow change from limited->unlimited blocks/inodes while any
3577 * are in use; but we must separately disallow unlimited->limited, because in
3578 * that case we have no record of how much is already in use.
3579 */
3580static int shmem_reconfigure(struct fs_context *fc)
3581{
3582 struct shmem_options *ctx = fc->fs_private;
3583 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
3584 unsigned long inodes;
3585 const char *err;
3586
3587 spin_lock(&sbinfo->stat_lock);
3588 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3589 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
3590 if (!sbinfo->max_blocks) {
3591 err = "Cannot retroactively limit size";
3592 goto out;
3593 }
3594 if (percpu_counter_compare(&sbinfo->used_blocks,
3595 ctx->blocks) > 0) {
3596 err = "Too small a size for current use";
3597 goto out;
3598 }
3599 }
3600 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
3601 if (!sbinfo->max_inodes) {
3602 err = "Cannot retroactively limit inodes";
3603 goto out;
3604 }
3605 if (ctx->inodes < inodes) {
3606 err = "Too few inodes for current use";
3607 goto out;
3608 }
3609 }
3610
3611 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
3612 sbinfo->next_ino > UINT_MAX) {
3613 err = "Current inum too high to switch to 32-bit inums";
3614 goto out;
3615 }
3616
3617 if (ctx->seen & SHMEM_SEEN_HUGE)
3618 sbinfo->huge = ctx->huge;
3619 if (ctx->seen & SHMEM_SEEN_INUMS)
3620 sbinfo->full_inums = ctx->full_inums;
3621 if (ctx->seen & SHMEM_SEEN_BLOCKS)
3622 sbinfo->max_blocks = ctx->blocks;
3623 if (ctx->seen & SHMEM_SEEN_INODES) {
3624 sbinfo->max_inodes = ctx->inodes;
3625 sbinfo->free_inodes = ctx->inodes - inodes;
3626 }
3627
3628 /*
3629 * Preserve previous mempolicy unless mpol remount option was specified.
3630 */
3631 if (ctx->mpol) {
3632 mpol_put(sbinfo->mpol);
3633 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
3634 ctx->mpol = NULL;
3635 }
3636 spin_unlock(&sbinfo->stat_lock);
3637 return 0;
3638out:
3639 spin_unlock(&sbinfo->stat_lock);
3640 return invalfc(fc, "%s", err);
3641}
3642
3643static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3644{
3645 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3646
3647 if (sbinfo->max_blocks != shmem_default_max_blocks())
3648 seq_printf(seq, ",size=%luk",
3649 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3650 if (sbinfo->max_inodes != shmem_default_max_inodes())
3651 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3652 if (sbinfo->mode != (0777 | S_ISVTX))
3653 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3654 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3655 seq_printf(seq, ",uid=%u",
3656 from_kuid_munged(&init_user_ns, sbinfo->uid));
3657 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3658 seq_printf(seq, ",gid=%u",
3659 from_kgid_munged(&init_user_ns, sbinfo->gid));
3660
3661 /*
3662 * Showing inode{64,32} might be useful even if it's the system default,
3663 * since then people don't have to resort to checking both here and
3664 * /proc/config.gz to confirm 64-bit inums were successfully applied
3665 * (which may not even exist if IKCONFIG_PROC isn't enabled).
3666 *
3667 * We hide it when inode64 isn't the default and we are using 32-bit
3668 * inodes, since that probably just means the feature isn't even under
3669 * consideration.
3670 *
3671 * As such:
3672 *
3673 * +-----------------+-----------------+
3674 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
3675 * +------------------+-----------------+-----------------+
3676 * | full_inums=true | show | show |
3677 * | full_inums=false | show | hide |
3678 * +------------------+-----------------+-----------------+
3679 *
3680 */
3681 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
3682 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
3683#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3684 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3685 if (sbinfo->huge)
3686 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3687#endif
3688 shmem_show_mpol(seq, sbinfo->mpol);
3689 return 0;
3690}
3691
3692#endif /* CONFIG_TMPFS */
3693
3694static void shmem_put_super(struct super_block *sb)
3695{
3696 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3697
3698 free_percpu(sbinfo->ino_batch);
3699 percpu_counter_destroy(&sbinfo->used_blocks);
3700 mpol_put(sbinfo->mpol);
3701 kfree(sbinfo);
3702 sb->s_fs_info = NULL;
3703}
3704
3705static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
3706{
3707 struct shmem_options *ctx = fc->fs_private;
3708 struct inode *inode;
3709 struct shmem_sb_info *sbinfo;
3710 int err = -ENOMEM;
3711
3712 /* Round up to L1_CACHE_BYTES to resist false sharing */
3713 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3714 L1_CACHE_BYTES), GFP_KERNEL);
3715 if (!sbinfo)
3716 return -ENOMEM;
3717
3718 sb->s_fs_info = sbinfo;
3719
3720#ifdef CONFIG_TMPFS
3721 /*
3722 * Per default we only allow half of the physical ram per
3723 * tmpfs instance, limiting inodes to one per page of lowmem;
3724 * but the internal instance is left unlimited.
3725 */
3726 if (!(sb->s_flags & SB_KERNMOUNT)) {
3727 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
3728 ctx->blocks = shmem_default_max_blocks();
3729 if (!(ctx->seen & SHMEM_SEEN_INODES))
3730 ctx->inodes = shmem_default_max_inodes();
3731 if (!(ctx->seen & SHMEM_SEEN_INUMS))
3732 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
3733 } else {
3734 sb->s_flags |= SB_NOUSER;
3735 }
3736 sb->s_export_op = &shmem_export_ops;
3737 sb->s_flags |= SB_NOSEC;
3738#else
3739 sb->s_flags |= SB_NOUSER;
3740#endif
3741 sbinfo->max_blocks = ctx->blocks;
3742 sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
3743 if (sb->s_flags & SB_KERNMOUNT) {
3744 sbinfo->ino_batch = alloc_percpu(ino_t);
3745 if (!sbinfo->ino_batch)
3746 goto failed;
3747 }
3748 sbinfo->uid = ctx->uid;
3749 sbinfo->gid = ctx->gid;
3750 sbinfo->full_inums = ctx->full_inums;
3751 sbinfo->mode = ctx->mode;
3752 sbinfo->huge = ctx->huge;
3753 sbinfo->mpol = ctx->mpol;
3754 ctx->mpol = NULL;
3755
3756 spin_lock_init(&sbinfo->stat_lock);
3757 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3758 goto failed;
3759 spin_lock_init(&sbinfo->shrinklist_lock);
3760 INIT_LIST_HEAD(&sbinfo->shrinklist);
3761
3762 sb->s_maxbytes = MAX_LFS_FILESIZE;
3763 sb->s_blocksize = PAGE_SIZE;
3764 sb->s_blocksize_bits = PAGE_SHIFT;
3765 sb->s_magic = TMPFS_MAGIC;
3766 sb->s_op = &shmem_ops;
3767 sb->s_time_gran = 1;
3768#ifdef CONFIG_TMPFS_XATTR
3769 sb->s_xattr = shmem_xattr_handlers;
3770#endif
3771#ifdef CONFIG_TMPFS_POSIX_ACL
3772 sb->s_flags |= SB_POSIXACL;
3773#endif
3774 uuid_gen(&sb->s_uuid);
3775
3776 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3777 if (!inode)
3778 goto failed;
3779 inode->i_uid = sbinfo->uid;
3780 inode->i_gid = sbinfo->gid;
3781 sb->s_root = d_make_root(inode);
3782 if (!sb->s_root)
3783 goto failed;
3784 return 0;
3785
3786failed:
3787 shmem_put_super(sb);
3788 return err;
3789}
3790
3791static int shmem_get_tree(struct fs_context *fc)
3792{
3793 return get_tree_nodev(fc, shmem_fill_super);
3794}
3795
3796static void shmem_free_fc(struct fs_context *fc)
3797{
3798 struct shmem_options *ctx = fc->fs_private;
3799
3800 if (ctx) {
3801 mpol_put(ctx->mpol);
3802 kfree(ctx);
3803 }
3804}
3805
3806static const struct fs_context_operations shmem_fs_context_ops = {
3807 .free = shmem_free_fc,
3808 .get_tree = shmem_get_tree,
3809#ifdef CONFIG_TMPFS
3810 .parse_monolithic = shmem_parse_options,
3811 .parse_param = shmem_parse_one,
3812 .reconfigure = shmem_reconfigure,
3813#endif
3814};
3815
3816static struct kmem_cache *shmem_inode_cachep;
3817
3818static struct inode *shmem_alloc_inode(struct super_block *sb)
3819{
3820 struct shmem_inode_info *info;
3821 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3822 if (!info)
3823 return NULL;
3824 return &info->vfs_inode;
3825}
3826
3827static void shmem_free_in_core_inode(struct inode *inode)
3828{
3829 if (S_ISLNK(inode->i_mode))
3830 kfree(inode->i_link);
3831 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3832}
3833
3834static void shmem_destroy_inode(struct inode *inode)
3835{
3836 if (S_ISREG(inode->i_mode))
3837 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3838}
3839
3840static void shmem_init_inode(void *foo)
3841{
3842 struct shmem_inode_info *info = foo;
3843 inode_init_once(&info->vfs_inode);
3844}
3845
3846static void shmem_init_inodecache(void)
3847{
3848 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3849 sizeof(struct shmem_inode_info),
3850 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3851}
3852
3853static void shmem_destroy_inodecache(void)
3854{
3855 kmem_cache_destroy(shmem_inode_cachep);
3856}
3857
3858static const struct address_space_operations shmem_aops = {
3859 .writepage = shmem_writepage,
3860 .set_page_dirty = __set_page_dirty_no_writeback,
3861#ifdef CONFIG_TMPFS
3862 .write_begin = shmem_write_begin,
3863 .write_end = shmem_write_end,
3864#endif
3865#ifdef CONFIG_MIGRATION
3866 .migratepage = migrate_page,
3867#endif
3868 .error_remove_page = generic_error_remove_page,
3869};
3870
3871static const struct file_operations shmem_file_operations = {
3872 .mmap = shmem_mmap,
3873 .get_unmapped_area = shmem_get_unmapped_area,
3874#ifdef CONFIG_TMPFS
3875 .llseek = shmem_file_llseek,
3876 .read_iter = shmem_file_read_iter,
3877 .write_iter = generic_file_write_iter,
3878 .fsync = noop_fsync,
3879 .splice_read = generic_file_splice_read,
3880 .splice_write = iter_file_splice_write,
3881 .fallocate = shmem_fallocate,
3882#endif
3883};
3884
3885static const struct inode_operations shmem_inode_operations = {
3886 .getattr = shmem_getattr,
3887 .setattr = shmem_setattr,
3888#ifdef CONFIG_TMPFS_XATTR
3889 .listxattr = shmem_listxattr,
3890 .set_acl = simple_set_acl,
3891#endif
3892};
3893
3894static const struct inode_operations shmem_dir_inode_operations = {
3895#ifdef CONFIG_TMPFS
3896 .create = shmem_create,
3897 .lookup = simple_lookup,
3898 .link = shmem_link,
3899 .unlink = shmem_unlink,
3900 .symlink = shmem_symlink,
3901 .mkdir = shmem_mkdir,
3902 .rmdir = shmem_rmdir,
3903 .mknod = shmem_mknod,
3904 .rename = shmem_rename2,
3905 .tmpfile = shmem_tmpfile,
3906#endif
3907#ifdef CONFIG_TMPFS_XATTR
3908 .listxattr = shmem_listxattr,
3909#endif
3910#ifdef CONFIG_TMPFS_POSIX_ACL
3911 .setattr = shmem_setattr,
3912 .set_acl = simple_set_acl,
3913#endif
3914};
3915
3916static const struct inode_operations shmem_special_inode_operations = {
3917#ifdef CONFIG_TMPFS_XATTR
3918 .listxattr = shmem_listxattr,
3919#endif
3920#ifdef CONFIG_TMPFS_POSIX_ACL
3921 .setattr = shmem_setattr,
3922 .set_acl = simple_set_acl,
3923#endif
3924};
3925
3926static const struct super_operations shmem_ops = {
3927 .alloc_inode = shmem_alloc_inode,
3928 .free_inode = shmem_free_in_core_inode,
3929 .destroy_inode = shmem_destroy_inode,
3930#ifdef CONFIG_TMPFS
3931 .statfs = shmem_statfs,
3932 .show_options = shmem_show_options,
3933#endif
3934 .evict_inode = shmem_evict_inode,
3935 .drop_inode = generic_delete_inode,
3936 .put_super = shmem_put_super,
3937#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3938 .nr_cached_objects = shmem_unused_huge_count,
3939 .free_cached_objects = shmem_unused_huge_scan,
3940#endif
3941};
3942
3943static const struct vm_operations_struct shmem_vm_ops = {
3944 .fault = shmem_fault,
3945 .map_pages = filemap_map_pages,
3946#ifdef CONFIG_NUMA
3947 .set_policy = shmem_set_policy,
3948 .get_policy = shmem_get_policy,
3949#endif
3950};
3951
3952int shmem_init_fs_context(struct fs_context *fc)
3953{
3954 struct shmem_options *ctx;
3955
3956 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
3957 if (!ctx)
3958 return -ENOMEM;
3959
3960 ctx->mode = 0777 | S_ISVTX;
3961 ctx->uid = current_fsuid();
3962 ctx->gid = current_fsgid();
3963
3964 fc->fs_private = ctx;
3965 fc->ops = &shmem_fs_context_ops;
3966 return 0;
3967}
3968
3969static struct file_system_type shmem_fs_type = {
3970 .owner = THIS_MODULE,
3971 .name = "tmpfs",
3972 .init_fs_context = shmem_init_fs_context,
3973#ifdef CONFIG_TMPFS
3974 .parameters = shmem_fs_parameters,
3975#endif
3976 .kill_sb = kill_litter_super,
3977 .fs_flags = FS_USERNS_MOUNT,
3978};
3979
3980int __init shmem_init(void)
3981{
3982 int error;
3983
3984 shmem_init_inodecache();
3985
3986 error = register_filesystem(&shmem_fs_type);
3987 if (error) {
3988 pr_err("Could not register tmpfs\n");
3989 goto out2;
3990 }
3991
3992 shm_mnt = kern_mount(&shmem_fs_type);
3993 if (IS_ERR(shm_mnt)) {
3994 error = PTR_ERR(shm_mnt);
3995 pr_err("Could not kern_mount tmpfs\n");
3996 goto out1;
3997 }
3998
3999#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4000 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
4001 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4002 else
4003 shmem_huge = 0; /* just in case it was patched */
4004#endif
4005 return 0;
4006
4007out1:
4008 unregister_filesystem(&shmem_fs_type);
4009out2:
4010 shmem_destroy_inodecache();
4011 shm_mnt = ERR_PTR(error);
4012 return error;
4013}
4014
4015#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
4016static ssize_t shmem_enabled_show(struct kobject *kobj,
4017 struct kobj_attribute *attr, char *buf)
4018{
4019 static const int values[] = {
4020 SHMEM_HUGE_ALWAYS,
4021 SHMEM_HUGE_WITHIN_SIZE,
4022 SHMEM_HUGE_ADVISE,
4023 SHMEM_HUGE_NEVER,
4024 SHMEM_HUGE_DENY,
4025 SHMEM_HUGE_FORCE,
4026 };
4027 int i, count;
4028
4029 for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
4030 const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
4031
4032 count += sprintf(buf + count, fmt,
4033 shmem_format_huge(values[i]));
4034 }
4035 buf[count - 1] = '\n';
4036 return count;
4037}
4038
4039static ssize_t shmem_enabled_store(struct kobject *kobj,
4040 struct kobj_attribute *attr, const char *buf, size_t count)
4041{
4042 char tmp[16];
4043 int huge;
4044
4045 if (count + 1 > sizeof(tmp))
4046 return -EINVAL;
4047 memcpy(tmp, buf, count);
4048 tmp[count] = '\0';
4049 if (count && tmp[count - 1] == '\n')
4050 tmp[count - 1] = '\0';
4051
4052 huge = shmem_parse_huge(tmp);
4053 if (huge == -EINVAL)
4054 return -EINVAL;
4055 if (!has_transparent_hugepage() &&
4056 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4057 return -EINVAL;
4058
4059 shmem_huge = huge;
4060 if (shmem_huge > SHMEM_HUGE_DENY)
4061 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4062 return count;
4063}
4064
4065struct kobj_attribute shmem_enabled_attr =
4066 __ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
4067#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4068
4069#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4070bool shmem_huge_enabled(struct vm_area_struct *vma)
4071{
4072 struct inode *inode = file_inode(vma->vm_file);
4073 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
4074 loff_t i_size;
4075 pgoff_t off;
4076
4077 if ((vma->vm_flags & VM_NOHUGEPAGE) ||
4078 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
4079 return false;
4080 if (shmem_huge == SHMEM_HUGE_FORCE)
4081 return true;
4082 if (shmem_huge == SHMEM_HUGE_DENY)
4083 return false;
4084 switch (sbinfo->huge) {
4085 case SHMEM_HUGE_NEVER:
4086 return false;
4087 case SHMEM_HUGE_ALWAYS:
4088 return true;
4089 case SHMEM_HUGE_WITHIN_SIZE:
4090 off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
4091 i_size = round_up(i_size_read(inode), PAGE_SIZE);
4092 if (i_size >= HPAGE_PMD_SIZE &&
4093 i_size >> PAGE_SHIFT >= off)
4094 return true;
4095 fallthrough;
4096 case SHMEM_HUGE_ADVISE:
4097 /* TODO: implement fadvise() hints */
4098 return (vma->vm_flags & VM_HUGEPAGE);
4099 default:
4100 VM_BUG_ON(1);
4101 return false;
4102 }
4103}
4104#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4105
4106#else /* !CONFIG_SHMEM */
4107
4108/*
4109 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4110 *
4111 * This is intended for small system where the benefits of the full
4112 * shmem code (swap-backed and resource-limited) are outweighed by
4113 * their complexity. On systems without swap this code should be
4114 * effectively equivalent, but much lighter weight.
4115 */
4116
4117static struct file_system_type shmem_fs_type = {
4118 .name = "tmpfs",
4119 .init_fs_context = ramfs_init_fs_context,
4120 .parameters = ramfs_fs_parameters,
4121 .kill_sb = kill_litter_super,
4122 .fs_flags = FS_USERNS_MOUNT,
4123};
4124
4125int __init shmem_init(void)
4126{
4127 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4128
4129 shm_mnt = kern_mount(&shmem_fs_type);
4130 BUG_ON(IS_ERR(shm_mnt));
4131
4132 return 0;
4133}
4134
4135int shmem_unuse(unsigned int type, bool frontswap,
4136 unsigned long *fs_pages_to_unuse)
4137{
4138 return 0;
4139}
4140
4141int shmem_lock(struct file *file, int lock, struct user_struct *user)
4142{
4143 return 0;
4144}
4145
4146void shmem_unlock_mapping(struct address_space *mapping)
4147{
4148}
4149
4150#ifdef CONFIG_MMU
4151unsigned long shmem_get_unmapped_area(struct file *file,
4152 unsigned long addr, unsigned long len,
4153 unsigned long pgoff, unsigned long flags)
4154{
4155 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4156}
4157#endif
4158
4159void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4160{
4161 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4162}
4163EXPORT_SYMBOL_GPL(shmem_truncate_range);
4164
4165#define shmem_vm_ops generic_file_vm_ops
4166#define shmem_file_operations ramfs_file_operations
4167#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4168#define shmem_acct_size(flags, size) 0
4169#define shmem_unacct_size(flags, size) do {} while (0)
4170
4171#endif /* CONFIG_SHMEM */
4172
4173/* common code */
4174
4175static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4176 unsigned long flags, unsigned int i_flags)
4177{
4178 struct inode *inode;
4179 struct file *res;
4180
4181 if (IS_ERR(mnt))
4182 return ERR_CAST(mnt);
4183
4184 if (size < 0 || size > MAX_LFS_FILESIZE)
4185 return ERR_PTR(-EINVAL);
4186
4187 if (shmem_acct_size(flags, size))
4188 return ERR_PTR(-ENOMEM);
4189
4190 inode = shmem_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0,
4191 flags);
4192 if (unlikely(!inode)) {
4193 shmem_unacct_size(flags, size);
4194 return ERR_PTR(-ENOSPC);
4195 }
4196 inode->i_flags |= i_flags;
4197 inode->i_size = size;
4198 clear_nlink(inode); /* It is unlinked */
4199 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4200 if (!IS_ERR(res))
4201 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4202 &shmem_file_operations);
4203 if (IS_ERR(res))
4204 iput(inode);
4205 return res;
4206}
4207
4208/**
4209 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4210 * kernel internal. There will be NO LSM permission checks against the
4211 * underlying inode. So users of this interface must do LSM checks at a
4212 * higher layer. The users are the big_key and shm implementations. LSM
4213 * checks are provided at the key or shm level rather than the inode.
4214 * @name: name for dentry (to be seen in /proc/<pid>/maps
4215 * @size: size to be set for the file
4216 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4217 */
4218struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4219{
4220 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4221}
4222
4223/**
4224 * shmem_file_setup - get an unlinked file living in tmpfs
4225 * @name: name for dentry (to be seen in /proc/<pid>/maps
4226 * @size: size to be set for the file
4227 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4228 */
4229struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4230{
4231 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4232}
4233EXPORT_SYMBOL_GPL(shmem_file_setup);
4234
4235/**
4236 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4237 * @mnt: the tmpfs mount where the file will be created
4238 * @name: name for dentry (to be seen in /proc/<pid>/maps
4239 * @size: size to be set for the file
4240 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4241 */
4242struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4243 loff_t size, unsigned long flags)
4244{
4245 return __shmem_file_setup(mnt, name, size, flags, 0);
4246}
4247EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4248
4249/**
4250 * shmem_zero_setup - setup a shared anonymous mapping
4251 * @vma: the vma to be mmapped is prepared by do_mmap
4252 */
4253int shmem_zero_setup(struct vm_area_struct *vma)
4254{
4255 struct file *file;
4256 loff_t size = vma->vm_end - vma->vm_start;
4257
4258 /*
4259 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4260 * between XFS directory reading and selinux: since this file is only
4261 * accessible to the user through its mapping, use S_PRIVATE flag to
4262 * bypass file security, in the same way as shmem_kernel_file_setup().
4263 */
4264 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4265 if (IS_ERR(file))
4266 return PTR_ERR(file);
4267
4268 if (vma->vm_file)
4269 fput(vma->vm_file);
4270 vma->vm_file = file;
4271 vma->vm_ops = &shmem_vm_ops;
4272
4273 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
4274 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4275 (vma->vm_end & HPAGE_PMD_MASK)) {
4276 khugepaged_enter(vma, vma->vm_flags);
4277 }
4278
4279 return 0;
4280}
4281
4282/**
4283 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4284 * @mapping: the page's address_space
4285 * @index: the page index
4286 * @gfp: the page allocator flags to use if allocating
4287 *
4288 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4289 * with any new page allocations done using the specified allocation flags.
4290 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4291 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4292 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4293 *
4294 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4295 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4296 */
4297struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4298 pgoff_t index, gfp_t gfp)
4299{
4300#ifdef CONFIG_SHMEM
4301 struct inode *inode = mapping->host;
4302 struct page *page;
4303 int error;
4304
4305 BUG_ON(mapping->a_ops != &shmem_aops);
4306 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4307 gfp, NULL, NULL, NULL);
4308 if (error)
4309 page = ERR_PTR(error);
4310 else
4311 unlock_page(page);
4312 return page;
4313#else
4314 /*
4315 * The tiny !SHMEM case uses ramfs without swap
4316 */
4317 return read_cache_page_gfp(mapping, index, gfp);
4318#endif
4319}
4320EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
1/*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 *
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
17 *
18 * tiny-shmem:
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 *
21 * This file is released under the GPL.
22 */
23
24#include <linux/fs.h>
25#include <linux/init.h>
26#include <linux/vfs.h>
27#include <linux/mount.h>
28#include <linux/ramfs.h>
29#include <linux/pagemap.h>
30#include <linux/file.h>
31#include <linux/fileattr.h>
32#include <linux/mm.h>
33#include <linux/random.h>
34#include <linux/sched/signal.h>
35#include <linux/export.h>
36#include <linux/shmem_fs.h>
37#include <linux/swap.h>
38#include <linux/uio.h>
39#include <linux/hugetlb.h>
40#include <linux/fs_parser.h>
41#include <linux/swapfile.h>
42#include <linux/iversion.h>
43#include <linux/unicode.h>
44#include "swap.h"
45
46static struct vfsmount *shm_mnt __ro_after_init;
47
48#ifdef CONFIG_SHMEM
49/*
50 * This virtual memory filesystem is heavily based on the ramfs. It
51 * extends ramfs by the ability to use swap and honor resource limits
52 * which makes it a completely usable filesystem.
53 */
54
55#include <linux/xattr.h>
56#include <linux/exportfs.h>
57#include <linux/posix_acl.h>
58#include <linux/posix_acl_xattr.h>
59#include <linux/mman.h>
60#include <linux/string.h>
61#include <linux/slab.h>
62#include <linux/backing-dev.h>
63#include <linux/writeback.h>
64#include <linux/pagevec.h>
65#include <linux/percpu_counter.h>
66#include <linux/falloc.h>
67#include <linux/splice.h>
68#include <linux/security.h>
69#include <linux/swapops.h>
70#include <linux/mempolicy.h>
71#include <linux/namei.h>
72#include <linux/ctype.h>
73#include <linux/migrate.h>
74#include <linux/highmem.h>
75#include <linux/seq_file.h>
76#include <linux/magic.h>
77#include <linux/syscalls.h>
78#include <linux/fcntl.h>
79#include <uapi/linux/memfd.h>
80#include <linux/rmap.h>
81#include <linux/uuid.h>
82#include <linux/quotaops.h>
83#include <linux/rcupdate_wait.h>
84
85#include <linux/uaccess.h>
86
87#include "internal.h"
88
89#define BLOCKS_PER_PAGE (PAGE_SIZE/512)
90#define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
91
92/* Pretend that each entry is of this size in directory's i_size */
93#define BOGO_DIRENT_SIZE 20
94
95/* Pretend that one inode + its dentry occupy this much memory */
96#define BOGO_INODE_SIZE 1024
97
98/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
99#define SHORT_SYMLINK_LEN 128
100
101/*
102 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
103 * inode->i_private (with i_rwsem making sure that it has only one user at
104 * a time): we would prefer not to enlarge the shmem inode just for that.
105 */
106struct shmem_falloc {
107 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
108 pgoff_t start; /* start of range currently being fallocated */
109 pgoff_t next; /* the next page offset to be fallocated */
110 pgoff_t nr_falloced; /* how many new pages have been fallocated */
111 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
112};
113
114struct shmem_options {
115 unsigned long long blocks;
116 unsigned long long inodes;
117 struct mempolicy *mpol;
118 kuid_t uid;
119 kgid_t gid;
120 umode_t mode;
121 bool full_inums;
122 int huge;
123 int seen;
124 bool noswap;
125 unsigned short quota_types;
126 struct shmem_quota_limits qlimits;
127#if IS_ENABLED(CONFIG_UNICODE)
128 struct unicode_map *encoding;
129 bool strict_encoding;
130#endif
131#define SHMEM_SEEN_BLOCKS 1
132#define SHMEM_SEEN_INODES 2
133#define SHMEM_SEEN_HUGE 4
134#define SHMEM_SEEN_INUMS 8
135#define SHMEM_SEEN_NOSWAP 16
136#define SHMEM_SEEN_QUOTA 32
137};
138
139#ifdef CONFIG_TRANSPARENT_HUGEPAGE
140static unsigned long huge_shmem_orders_always __read_mostly;
141static unsigned long huge_shmem_orders_madvise __read_mostly;
142static unsigned long huge_shmem_orders_inherit __read_mostly;
143static unsigned long huge_shmem_orders_within_size __read_mostly;
144static bool shmem_orders_configured __initdata;
145#endif
146
147#ifdef CONFIG_TMPFS
148static unsigned long shmem_default_max_blocks(void)
149{
150 return totalram_pages() / 2;
151}
152
153static unsigned long shmem_default_max_inodes(void)
154{
155 unsigned long nr_pages = totalram_pages();
156
157 return min3(nr_pages - totalhigh_pages(), nr_pages / 2,
158 ULONG_MAX / BOGO_INODE_SIZE);
159}
160#endif
161
162static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
163 struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
164 struct vm_area_struct *vma, vm_fault_t *fault_type);
165
166static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
167{
168 return sb->s_fs_info;
169}
170
171/*
172 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
173 * for shared memory and for shared anonymous (/dev/zero) mappings
174 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
175 * consistent with the pre-accounting of private mappings ...
176 */
177static inline int shmem_acct_size(unsigned long flags, loff_t size)
178{
179 return (flags & VM_NORESERVE) ?
180 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
181}
182
183static inline void shmem_unacct_size(unsigned long flags, loff_t size)
184{
185 if (!(flags & VM_NORESERVE))
186 vm_unacct_memory(VM_ACCT(size));
187}
188
189static inline int shmem_reacct_size(unsigned long flags,
190 loff_t oldsize, loff_t newsize)
191{
192 if (!(flags & VM_NORESERVE)) {
193 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
194 return security_vm_enough_memory_mm(current->mm,
195 VM_ACCT(newsize) - VM_ACCT(oldsize));
196 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
197 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
198 }
199 return 0;
200}
201
202/*
203 * ... whereas tmpfs objects are accounted incrementally as
204 * pages are allocated, in order to allow large sparse files.
205 * shmem_get_folio reports shmem_acct_blocks failure as -ENOSPC not -ENOMEM,
206 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
207 */
208static inline int shmem_acct_blocks(unsigned long flags, long pages)
209{
210 if (!(flags & VM_NORESERVE))
211 return 0;
212
213 return security_vm_enough_memory_mm(current->mm,
214 pages * VM_ACCT(PAGE_SIZE));
215}
216
217static inline void shmem_unacct_blocks(unsigned long flags, long pages)
218{
219 if (flags & VM_NORESERVE)
220 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
221}
222
223static int shmem_inode_acct_blocks(struct inode *inode, long pages)
224{
225 struct shmem_inode_info *info = SHMEM_I(inode);
226 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
227 int err = -ENOSPC;
228
229 if (shmem_acct_blocks(info->flags, pages))
230 return err;
231
232 might_sleep(); /* when quotas */
233 if (sbinfo->max_blocks) {
234 if (!percpu_counter_limited_add(&sbinfo->used_blocks,
235 sbinfo->max_blocks, pages))
236 goto unacct;
237
238 err = dquot_alloc_block_nodirty(inode, pages);
239 if (err) {
240 percpu_counter_sub(&sbinfo->used_blocks, pages);
241 goto unacct;
242 }
243 } else {
244 err = dquot_alloc_block_nodirty(inode, pages);
245 if (err)
246 goto unacct;
247 }
248
249 return 0;
250
251unacct:
252 shmem_unacct_blocks(info->flags, pages);
253 return err;
254}
255
256static void shmem_inode_unacct_blocks(struct inode *inode, long pages)
257{
258 struct shmem_inode_info *info = SHMEM_I(inode);
259 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
260
261 might_sleep(); /* when quotas */
262 dquot_free_block_nodirty(inode, pages);
263
264 if (sbinfo->max_blocks)
265 percpu_counter_sub(&sbinfo->used_blocks, pages);
266 shmem_unacct_blocks(info->flags, pages);
267}
268
269static const struct super_operations shmem_ops;
270static const struct address_space_operations shmem_aops;
271static const struct file_operations shmem_file_operations;
272static const struct inode_operations shmem_inode_operations;
273static const struct inode_operations shmem_dir_inode_operations;
274static const struct inode_operations shmem_special_inode_operations;
275static const struct vm_operations_struct shmem_vm_ops;
276static const struct vm_operations_struct shmem_anon_vm_ops;
277static struct file_system_type shmem_fs_type;
278
279bool shmem_mapping(struct address_space *mapping)
280{
281 return mapping->a_ops == &shmem_aops;
282}
283EXPORT_SYMBOL_GPL(shmem_mapping);
284
285bool vma_is_anon_shmem(struct vm_area_struct *vma)
286{
287 return vma->vm_ops == &shmem_anon_vm_ops;
288}
289
290bool vma_is_shmem(struct vm_area_struct *vma)
291{
292 return vma_is_anon_shmem(vma) || vma->vm_ops == &shmem_vm_ops;
293}
294
295static LIST_HEAD(shmem_swaplist);
296static DEFINE_MUTEX(shmem_swaplist_mutex);
297
298#ifdef CONFIG_TMPFS_QUOTA
299
300static int shmem_enable_quotas(struct super_block *sb,
301 unsigned short quota_types)
302{
303 int type, err = 0;
304
305 sb_dqopt(sb)->flags |= DQUOT_QUOTA_SYS_FILE | DQUOT_NOLIST_DIRTY;
306 for (type = 0; type < SHMEM_MAXQUOTAS; type++) {
307 if (!(quota_types & (1 << type)))
308 continue;
309 err = dquot_load_quota_sb(sb, type, QFMT_SHMEM,
310 DQUOT_USAGE_ENABLED |
311 DQUOT_LIMITS_ENABLED);
312 if (err)
313 goto out_err;
314 }
315 return 0;
316
317out_err:
318 pr_warn("tmpfs: failed to enable quota tracking (type=%d, err=%d)\n",
319 type, err);
320 for (type--; type >= 0; type--)
321 dquot_quota_off(sb, type);
322 return err;
323}
324
325static void shmem_disable_quotas(struct super_block *sb)
326{
327 int type;
328
329 for (type = 0; type < SHMEM_MAXQUOTAS; type++)
330 dquot_quota_off(sb, type);
331}
332
333static struct dquot __rcu **shmem_get_dquots(struct inode *inode)
334{
335 return SHMEM_I(inode)->i_dquot;
336}
337#endif /* CONFIG_TMPFS_QUOTA */
338
339/*
340 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
341 * produces a novel ino for the newly allocated inode.
342 *
343 * It may also be called when making a hard link to permit the space needed by
344 * each dentry. However, in that case, no new inode number is needed since that
345 * internally draws from another pool of inode numbers (currently global
346 * get_next_ino()). This case is indicated by passing NULL as inop.
347 */
348#define SHMEM_INO_BATCH 1024
349static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
350{
351 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
352 ino_t ino;
353
354 if (!(sb->s_flags & SB_KERNMOUNT)) {
355 raw_spin_lock(&sbinfo->stat_lock);
356 if (sbinfo->max_inodes) {
357 if (sbinfo->free_ispace < BOGO_INODE_SIZE) {
358 raw_spin_unlock(&sbinfo->stat_lock);
359 return -ENOSPC;
360 }
361 sbinfo->free_ispace -= BOGO_INODE_SIZE;
362 }
363 if (inop) {
364 ino = sbinfo->next_ino++;
365 if (unlikely(is_zero_ino(ino)))
366 ino = sbinfo->next_ino++;
367 if (unlikely(!sbinfo->full_inums &&
368 ino > UINT_MAX)) {
369 /*
370 * Emulate get_next_ino uint wraparound for
371 * compatibility
372 */
373 if (IS_ENABLED(CONFIG_64BIT))
374 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
375 __func__, MINOR(sb->s_dev));
376 sbinfo->next_ino = 1;
377 ino = sbinfo->next_ino++;
378 }
379 *inop = ino;
380 }
381 raw_spin_unlock(&sbinfo->stat_lock);
382 } else if (inop) {
383 /*
384 * __shmem_file_setup, one of our callers, is lock-free: it
385 * doesn't hold stat_lock in shmem_reserve_inode since
386 * max_inodes is always 0, and is called from potentially
387 * unknown contexts. As such, use a per-cpu batched allocator
388 * which doesn't require the per-sb stat_lock unless we are at
389 * the batch boundary.
390 *
391 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
392 * shmem mounts are not exposed to userspace, so we don't need
393 * to worry about things like glibc compatibility.
394 */
395 ino_t *next_ino;
396
397 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
398 ino = *next_ino;
399 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
400 raw_spin_lock(&sbinfo->stat_lock);
401 ino = sbinfo->next_ino;
402 sbinfo->next_ino += SHMEM_INO_BATCH;
403 raw_spin_unlock(&sbinfo->stat_lock);
404 if (unlikely(is_zero_ino(ino)))
405 ino++;
406 }
407 *inop = ino;
408 *next_ino = ++ino;
409 put_cpu();
410 }
411
412 return 0;
413}
414
415static void shmem_free_inode(struct super_block *sb, size_t freed_ispace)
416{
417 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
418 if (sbinfo->max_inodes) {
419 raw_spin_lock(&sbinfo->stat_lock);
420 sbinfo->free_ispace += BOGO_INODE_SIZE + freed_ispace;
421 raw_spin_unlock(&sbinfo->stat_lock);
422 }
423}
424
425/**
426 * shmem_recalc_inode - recalculate the block usage of an inode
427 * @inode: inode to recalc
428 * @alloced: the change in number of pages allocated to inode
429 * @swapped: the change in number of pages swapped from inode
430 *
431 * We have to calculate the free blocks since the mm can drop
432 * undirtied hole pages behind our back.
433 *
434 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
435 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
436 */
437static void shmem_recalc_inode(struct inode *inode, long alloced, long swapped)
438{
439 struct shmem_inode_info *info = SHMEM_I(inode);
440 long freed;
441
442 spin_lock(&info->lock);
443 info->alloced += alloced;
444 info->swapped += swapped;
445 freed = info->alloced - info->swapped -
446 READ_ONCE(inode->i_mapping->nrpages);
447 /*
448 * Special case: whereas normally shmem_recalc_inode() is called
449 * after i_mapping->nrpages has already been adjusted (up or down),
450 * shmem_writepage() has to raise swapped before nrpages is lowered -
451 * to stop a racing shmem_recalc_inode() from thinking that a page has
452 * been freed. Compensate here, to avoid the need for a followup call.
453 */
454 if (swapped > 0)
455 freed += swapped;
456 if (freed > 0)
457 info->alloced -= freed;
458 spin_unlock(&info->lock);
459
460 /* The quota case may block */
461 if (freed > 0)
462 shmem_inode_unacct_blocks(inode, freed);
463}
464
465bool shmem_charge(struct inode *inode, long pages)
466{
467 struct address_space *mapping = inode->i_mapping;
468
469 if (shmem_inode_acct_blocks(inode, pages))
470 return false;
471
472 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
473 xa_lock_irq(&mapping->i_pages);
474 mapping->nrpages += pages;
475 xa_unlock_irq(&mapping->i_pages);
476
477 shmem_recalc_inode(inode, pages, 0);
478 return true;
479}
480
481void shmem_uncharge(struct inode *inode, long pages)
482{
483 /* pages argument is currently unused: keep it to help debugging */
484 /* nrpages adjustment done by __filemap_remove_folio() or caller */
485
486 shmem_recalc_inode(inode, 0, 0);
487}
488
489/*
490 * Replace item expected in xarray by a new item, while holding xa_lock.
491 */
492static int shmem_replace_entry(struct address_space *mapping,
493 pgoff_t index, void *expected, void *replacement)
494{
495 XA_STATE(xas, &mapping->i_pages, index);
496 void *item;
497
498 VM_BUG_ON(!expected);
499 VM_BUG_ON(!replacement);
500 item = xas_load(&xas);
501 if (item != expected)
502 return -ENOENT;
503 xas_store(&xas, replacement);
504 return 0;
505}
506
507/*
508 * Sometimes, before we decide whether to proceed or to fail, we must check
509 * that an entry was not already brought back from swap by a racing thread.
510 *
511 * Checking folio is not enough: by the time a swapcache folio is locked, it
512 * might be reused, and again be swapcache, using the same swap as before.
513 */
514static bool shmem_confirm_swap(struct address_space *mapping,
515 pgoff_t index, swp_entry_t swap)
516{
517 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
518}
519
520/*
521 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
522 *
523 * SHMEM_HUGE_NEVER:
524 * disables huge pages for the mount;
525 * SHMEM_HUGE_ALWAYS:
526 * enables huge pages for the mount;
527 * SHMEM_HUGE_WITHIN_SIZE:
528 * only allocate huge pages if the page will be fully within i_size,
529 * also respect fadvise()/madvise() hints;
530 * SHMEM_HUGE_ADVISE:
531 * only allocate huge pages if requested with fadvise()/madvise();
532 */
533
534#define SHMEM_HUGE_NEVER 0
535#define SHMEM_HUGE_ALWAYS 1
536#define SHMEM_HUGE_WITHIN_SIZE 2
537#define SHMEM_HUGE_ADVISE 3
538
539/*
540 * Special values.
541 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
542 *
543 * SHMEM_HUGE_DENY:
544 * disables huge on shm_mnt and all mounts, for emergency use;
545 * SHMEM_HUGE_FORCE:
546 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
547 *
548 */
549#define SHMEM_HUGE_DENY (-1)
550#define SHMEM_HUGE_FORCE (-2)
551
552#ifdef CONFIG_TRANSPARENT_HUGEPAGE
553/* ifdef here to avoid bloating shmem.o when not necessary */
554
555static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
556
557static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
558 loff_t write_end, bool shmem_huge_force,
559 unsigned long vm_flags)
560{
561 loff_t i_size;
562
563 if (HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER)
564 return false;
565 if (!S_ISREG(inode->i_mode))
566 return false;
567 if (shmem_huge == SHMEM_HUGE_DENY)
568 return false;
569 if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE)
570 return true;
571
572 switch (SHMEM_SB(inode->i_sb)->huge) {
573 case SHMEM_HUGE_ALWAYS:
574 return true;
575 case SHMEM_HUGE_WITHIN_SIZE:
576 index = round_up(index + 1, HPAGE_PMD_NR);
577 i_size = max(write_end, i_size_read(inode));
578 i_size = round_up(i_size, PAGE_SIZE);
579 if (i_size >> PAGE_SHIFT >= index)
580 return true;
581 fallthrough;
582 case SHMEM_HUGE_ADVISE:
583 if (vm_flags & VM_HUGEPAGE)
584 return true;
585 fallthrough;
586 default:
587 return false;
588 }
589}
590
591static int shmem_parse_huge(const char *str)
592{
593 int huge;
594
595 if (!str)
596 return -EINVAL;
597
598 if (!strcmp(str, "never"))
599 huge = SHMEM_HUGE_NEVER;
600 else if (!strcmp(str, "always"))
601 huge = SHMEM_HUGE_ALWAYS;
602 else if (!strcmp(str, "within_size"))
603 huge = SHMEM_HUGE_WITHIN_SIZE;
604 else if (!strcmp(str, "advise"))
605 huge = SHMEM_HUGE_ADVISE;
606 else if (!strcmp(str, "deny"))
607 huge = SHMEM_HUGE_DENY;
608 else if (!strcmp(str, "force"))
609 huge = SHMEM_HUGE_FORCE;
610 else
611 return -EINVAL;
612
613 if (!has_transparent_hugepage() &&
614 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
615 return -EINVAL;
616
617 /* Do not override huge allocation policy with non-PMD sized mTHP */
618 if (huge == SHMEM_HUGE_FORCE &&
619 huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
620 return -EINVAL;
621
622 return huge;
623}
624
625#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
626static const char *shmem_format_huge(int huge)
627{
628 switch (huge) {
629 case SHMEM_HUGE_NEVER:
630 return "never";
631 case SHMEM_HUGE_ALWAYS:
632 return "always";
633 case SHMEM_HUGE_WITHIN_SIZE:
634 return "within_size";
635 case SHMEM_HUGE_ADVISE:
636 return "advise";
637 case SHMEM_HUGE_DENY:
638 return "deny";
639 case SHMEM_HUGE_FORCE:
640 return "force";
641 default:
642 VM_BUG_ON(1);
643 return "bad_val";
644 }
645}
646#endif
647
648static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
649 struct shrink_control *sc, unsigned long nr_to_free)
650{
651 LIST_HEAD(list), *pos, *next;
652 struct inode *inode;
653 struct shmem_inode_info *info;
654 struct folio *folio;
655 unsigned long batch = sc ? sc->nr_to_scan : 128;
656 unsigned long split = 0, freed = 0;
657
658 if (list_empty(&sbinfo->shrinklist))
659 return SHRINK_STOP;
660
661 spin_lock(&sbinfo->shrinklist_lock);
662 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
663 info = list_entry(pos, struct shmem_inode_info, shrinklist);
664
665 /* pin the inode */
666 inode = igrab(&info->vfs_inode);
667
668 /* inode is about to be evicted */
669 if (!inode) {
670 list_del_init(&info->shrinklist);
671 goto next;
672 }
673
674 list_move(&info->shrinklist, &list);
675next:
676 sbinfo->shrinklist_len--;
677 if (!--batch)
678 break;
679 }
680 spin_unlock(&sbinfo->shrinklist_lock);
681
682 list_for_each_safe(pos, next, &list) {
683 pgoff_t next, end;
684 loff_t i_size;
685 int ret;
686
687 info = list_entry(pos, struct shmem_inode_info, shrinklist);
688 inode = &info->vfs_inode;
689
690 if (nr_to_free && freed >= nr_to_free)
691 goto move_back;
692
693 i_size = i_size_read(inode);
694 folio = filemap_get_entry(inode->i_mapping, i_size / PAGE_SIZE);
695 if (!folio || xa_is_value(folio))
696 goto drop;
697
698 /* No large folio at the end of the file: nothing to split */
699 if (!folio_test_large(folio)) {
700 folio_put(folio);
701 goto drop;
702 }
703
704 /* Check if there is anything to gain from splitting */
705 next = folio_next_index(folio);
706 end = shmem_fallocend(inode, DIV_ROUND_UP(i_size, PAGE_SIZE));
707 if (end <= folio->index || end >= next) {
708 folio_put(folio);
709 goto drop;
710 }
711
712 /*
713 * Move the inode on the list back to shrinklist if we failed
714 * to lock the page at this time.
715 *
716 * Waiting for the lock may lead to deadlock in the
717 * reclaim path.
718 */
719 if (!folio_trylock(folio)) {
720 folio_put(folio);
721 goto move_back;
722 }
723
724 ret = split_folio(folio);
725 folio_unlock(folio);
726 folio_put(folio);
727
728 /* If split failed move the inode on the list back to shrinklist */
729 if (ret)
730 goto move_back;
731
732 freed += next - end;
733 split++;
734drop:
735 list_del_init(&info->shrinklist);
736 goto put;
737move_back:
738 /*
739 * Make sure the inode is either on the global list or deleted
740 * from any local list before iput() since it could be deleted
741 * in another thread once we put the inode (then the local list
742 * is corrupted).
743 */
744 spin_lock(&sbinfo->shrinklist_lock);
745 list_move(&info->shrinklist, &sbinfo->shrinklist);
746 sbinfo->shrinklist_len++;
747 spin_unlock(&sbinfo->shrinklist_lock);
748put:
749 iput(inode);
750 }
751
752 return split;
753}
754
755static long shmem_unused_huge_scan(struct super_block *sb,
756 struct shrink_control *sc)
757{
758 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
759
760 if (!READ_ONCE(sbinfo->shrinklist_len))
761 return SHRINK_STOP;
762
763 return shmem_unused_huge_shrink(sbinfo, sc, 0);
764}
765
766static long shmem_unused_huge_count(struct super_block *sb,
767 struct shrink_control *sc)
768{
769 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
770 return READ_ONCE(sbinfo->shrinklist_len);
771}
772#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
773
774#define shmem_huge SHMEM_HUGE_DENY
775
776static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
777 struct shrink_control *sc, unsigned long nr_to_free)
778{
779 return 0;
780}
781
782static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
783 loff_t write_end, bool shmem_huge_force,
784 unsigned long vm_flags)
785{
786 return false;
787}
788#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
789
790static void shmem_update_stats(struct folio *folio, int nr_pages)
791{
792 if (folio_test_pmd_mappable(folio))
793 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr_pages);
794 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
795 __lruvec_stat_mod_folio(folio, NR_SHMEM, nr_pages);
796}
797
798/*
799 * Somewhat like filemap_add_folio, but error if expected item has gone.
800 */
801static int shmem_add_to_page_cache(struct folio *folio,
802 struct address_space *mapping,
803 pgoff_t index, void *expected, gfp_t gfp)
804{
805 XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
806 long nr = folio_nr_pages(folio);
807
808 VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
809 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
810 VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
811
812 folio_ref_add(folio, nr);
813 folio->mapping = mapping;
814 folio->index = index;
815
816 gfp &= GFP_RECLAIM_MASK;
817 folio_throttle_swaprate(folio, gfp);
818
819 do {
820 xas_lock_irq(&xas);
821 if (expected != xas_find_conflict(&xas)) {
822 xas_set_err(&xas, -EEXIST);
823 goto unlock;
824 }
825 if (expected && xas_find_conflict(&xas)) {
826 xas_set_err(&xas, -EEXIST);
827 goto unlock;
828 }
829 xas_store(&xas, folio);
830 if (xas_error(&xas))
831 goto unlock;
832 shmem_update_stats(folio, nr);
833 mapping->nrpages += nr;
834unlock:
835 xas_unlock_irq(&xas);
836 } while (xas_nomem(&xas, gfp));
837
838 if (xas_error(&xas)) {
839 folio->mapping = NULL;
840 folio_ref_sub(folio, nr);
841 return xas_error(&xas);
842 }
843
844 return 0;
845}
846
847/*
848 * Somewhat like filemap_remove_folio, but substitutes swap for @folio.
849 */
850static void shmem_delete_from_page_cache(struct folio *folio, void *radswap)
851{
852 struct address_space *mapping = folio->mapping;
853 long nr = folio_nr_pages(folio);
854 int error;
855
856 xa_lock_irq(&mapping->i_pages);
857 error = shmem_replace_entry(mapping, folio->index, folio, radswap);
858 folio->mapping = NULL;
859 mapping->nrpages -= nr;
860 shmem_update_stats(folio, -nr);
861 xa_unlock_irq(&mapping->i_pages);
862 folio_put_refs(folio, nr);
863 BUG_ON(error);
864}
865
866/*
867 * Remove swap entry from page cache, free the swap and its page cache. Returns
868 * the number of pages being freed. 0 means entry not found in XArray (0 pages
869 * being freed).
870 */
871static long shmem_free_swap(struct address_space *mapping,
872 pgoff_t index, void *radswap)
873{
874 int order = xa_get_order(&mapping->i_pages, index);
875 void *old;
876
877 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
878 if (old != radswap)
879 return 0;
880 free_swap_and_cache_nr(radix_to_swp_entry(radswap), 1 << order);
881
882 return 1 << order;
883}
884
885/*
886 * Determine (in bytes) how many of the shmem object's pages mapped by the
887 * given offsets are swapped out.
888 *
889 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
890 * as long as the inode doesn't go away and racy results are not a problem.
891 */
892unsigned long shmem_partial_swap_usage(struct address_space *mapping,
893 pgoff_t start, pgoff_t end)
894{
895 XA_STATE(xas, &mapping->i_pages, start);
896 struct page *page;
897 unsigned long swapped = 0;
898 unsigned long max = end - 1;
899
900 rcu_read_lock();
901 xas_for_each(&xas, page, max) {
902 if (xas_retry(&xas, page))
903 continue;
904 if (xa_is_value(page))
905 swapped += 1 << xas_get_order(&xas);
906 if (xas.xa_index == max)
907 break;
908 if (need_resched()) {
909 xas_pause(&xas);
910 cond_resched_rcu();
911 }
912 }
913 rcu_read_unlock();
914
915 return swapped << PAGE_SHIFT;
916}
917
918/*
919 * Determine (in bytes) how many of the shmem object's pages mapped by the
920 * given vma is swapped out.
921 *
922 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
923 * as long as the inode doesn't go away and racy results are not a problem.
924 */
925unsigned long shmem_swap_usage(struct vm_area_struct *vma)
926{
927 struct inode *inode = file_inode(vma->vm_file);
928 struct shmem_inode_info *info = SHMEM_I(inode);
929 struct address_space *mapping = inode->i_mapping;
930 unsigned long swapped;
931
932 /* Be careful as we don't hold info->lock */
933 swapped = READ_ONCE(info->swapped);
934
935 /*
936 * The easier cases are when the shmem object has nothing in swap, or
937 * the vma maps it whole. Then we can simply use the stats that we
938 * already track.
939 */
940 if (!swapped)
941 return 0;
942
943 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
944 return swapped << PAGE_SHIFT;
945
946 /* Here comes the more involved part */
947 return shmem_partial_swap_usage(mapping, vma->vm_pgoff,
948 vma->vm_pgoff + vma_pages(vma));
949}
950
951/*
952 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
953 */
954void shmem_unlock_mapping(struct address_space *mapping)
955{
956 struct folio_batch fbatch;
957 pgoff_t index = 0;
958
959 folio_batch_init(&fbatch);
960 /*
961 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
962 */
963 while (!mapping_unevictable(mapping) &&
964 filemap_get_folios(mapping, &index, ~0UL, &fbatch)) {
965 check_move_unevictable_folios(&fbatch);
966 folio_batch_release(&fbatch);
967 cond_resched();
968 }
969}
970
971static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
972{
973 struct folio *folio;
974
975 /*
976 * At first avoid shmem_get_folio(,,,SGP_READ): that fails
977 * beyond i_size, and reports fallocated folios as holes.
978 */
979 folio = filemap_get_entry(inode->i_mapping, index);
980 if (!folio)
981 return folio;
982 if (!xa_is_value(folio)) {
983 folio_lock(folio);
984 if (folio->mapping == inode->i_mapping)
985 return folio;
986 /* The folio has been swapped out */
987 folio_unlock(folio);
988 folio_put(folio);
989 }
990 /*
991 * But read a folio back from swap if any of it is within i_size
992 * (although in some cases this is just a waste of time).
993 */
994 folio = NULL;
995 shmem_get_folio(inode, index, 0, &folio, SGP_READ);
996 return folio;
997}
998
999/*
1000 * Remove range of pages and swap entries from page cache, and free them.
1001 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
1002 */
1003static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
1004 bool unfalloc)
1005{
1006 struct address_space *mapping = inode->i_mapping;
1007 struct shmem_inode_info *info = SHMEM_I(inode);
1008 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
1009 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
1010 struct folio_batch fbatch;
1011 pgoff_t indices[PAGEVEC_SIZE];
1012 struct folio *folio;
1013 bool same_folio;
1014 long nr_swaps_freed = 0;
1015 pgoff_t index;
1016 int i;
1017
1018 if (lend == -1)
1019 end = -1; /* unsigned, so actually very big */
1020
1021 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
1022 info->fallocend = start;
1023
1024 folio_batch_init(&fbatch);
1025 index = start;
1026 while (index < end && find_lock_entries(mapping, &index, end - 1,
1027 &fbatch, indices)) {
1028 for (i = 0; i < folio_batch_count(&fbatch); i++) {
1029 folio = fbatch.folios[i];
1030
1031 if (xa_is_value(folio)) {
1032 if (unfalloc)
1033 continue;
1034 nr_swaps_freed += shmem_free_swap(mapping,
1035 indices[i], folio);
1036 continue;
1037 }
1038
1039 if (!unfalloc || !folio_test_uptodate(folio))
1040 truncate_inode_folio(mapping, folio);
1041 folio_unlock(folio);
1042 }
1043 folio_batch_remove_exceptionals(&fbatch);
1044 folio_batch_release(&fbatch);
1045 cond_resched();
1046 }
1047
1048 /*
1049 * When undoing a failed fallocate, we want none of the partial folio
1050 * zeroing and splitting below, but shall want to truncate the whole
1051 * folio when !uptodate indicates that it was added by this fallocate,
1052 * even when [lstart, lend] covers only a part of the folio.
1053 */
1054 if (unfalloc)
1055 goto whole_folios;
1056
1057 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
1058 folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT);
1059 if (folio) {
1060 same_folio = lend < folio_pos(folio) + folio_size(folio);
1061 folio_mark_dirty(folio);
1062 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
1063 start = folio_next_index(folio);
1064 if (same_folio)
1065 end = folio->index;
1066 }
1067 folio_unlock(folio);
1068 folio_put(folio);
1069 folio = NULL;
1070 }
1071
1072 if (!same_folio)
1073 folio = shmem_get_partial_folio(inode, lend >> PAGE_SHIFT);
1074 if (folio) {
1075 folio_mark_dirty(folio);
1076 if (!truncate_inode_partial_folio(folio, lstart, lend))
1077 end = folio->index;
1078 folio_unlock(folio);
1079 folio_put(folio);
1080 }
1081
1082whole_folios:
1083
1084 index = start;
1085 while (index < end) {
1086 cond_resched();
1087
1088 if (!find_get_entries(mapping, &index, end - 1, &fbatch,
1089 indices)) {
1090 /* If all gone or hole-punch or unfalloc, we're done */
1091 if (index == start || end != -1)
1092 break;
1093 /* But if truncating, restart to make sure all gone */
1094 index = start;
1095 continue;
1096 }
1097 for (i = 0; i < folio_batch_count(&fbatch); i++) {
1098 folio = fbatch.folios[i];
1099
1100 if (xa_is_value(folio)) {
1101 long swaps_freed;
1102
1103 if (unfalloc)
1104 continue;
1105 swaps_freed = shmem_free_swap(mapping, indices[i], folio);
1106 if (!swaps_freed) {
1107 /* Swap was replaced by page: retry */
1108 index = indices[i];
1109 break;
1110 }
1111 nr_swaps_freed += swaps_freed;
1112 continue;
1113 }
1114
1115 folio_lock(folio);
1116
1117 if (!unfalloc || !folio_test_uptodate(folio)) {
1118 if (folio_mapping(folio) != mapping) {
1119 /* Page was replaced by swap: retry */
1120 folio_unlock(folio);
1121 index = indices[i];
1122 break;
1123 }
1124 VM_BUG_ON_FOLIO(folio_test_writeback(folio),
1125 folio);
1126
1127 if (!folio_test_large(folio)) {
1128 truncate_inode_folio(mapping, folio);
1129 } else if (truncate_inode_partial_folio(folio, lstart, lend)) {
1130 /*
1131 * If we split a page, reset the loop so
1132 * that we pick up the new sub pages.
1133 * Otherwise the THP was entirely
1134 * dropped or the target range was
1135 * zeroed, so just continue the loop as
1136 * is.
1137 */
1138 if (!folio_test_large(folio)) {
1139 folio_unlock(folio);
1140 index = start;
1141 break;
1142 }
1143 }
1144 }
1145 folio_unlock(folio);
1146 }
1147 folio_batch_remove_exceptionals(&fbatch);
1148 folio_batch_release(&fbatch);
1149 }
1150
1151 shmem_recalc_inode(inode, 0, -nr_swaps_freed);
1152}
1153
1154void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1155{
1156 shmem_undo_range(inode, lstart, lend, false);
1157 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
1158 inode_inc_iversion(inode);
1159}
1160EXPORT_SYMBOL_GPL(shmem_truncate_range);
1161
1162static int shmem_getattr(struct mnt_idmap *idmap,
1163 const struct path *path, struct kstat *stat,
1164 u32 request_mask, unsigned int query_flags)
1165{
1166 struct inode *inode = path->dentry->d_inode;
1167 struct shmem_inode_info *info = SHMEM_I(inode);
1168
1169 if (info->alloced - info->swapped != inode->i_mapping->nrpages)
1170 shmem_recalc_inode(inode, 0, 0);
1171
1172 if (info->fsflags & FS_APPEND_FL)
1173 stat->attributes |= STATX_ATTR_APPEND;
1174 if (info->fsflags & FS_IMMUTABLE_FL)
1175 stat->attributes |= STATX_ATTR_IMMUTABLE;
1176 if (info->fsflags & FS_NODUMP_FL)
1177 stat->attributes |= STATX_ATTR_NODUMP;
1178 stat->attributes_mask |= (STATX_ATTR_APPEND |
1179 STATX_ATTR_IMMUTABLE |
1180 STATX_ATTR_NODUMP);
1181 generic_fillattr(idmap, request_mask, inode, stat);
1182
1183 if (shmem_huge_global_enabled(inode, 0, 0, false, 0))
1184 stat->blksize = HPAGE_PMD_SIZE;
1185
1186 if (request_mask & STATX_BTIME) {
1187 stat->result_mask |= STATX_BTIME;
1188 stat->btime.tv_sec = info->i_crtime.tv_sec;
1189 stat->btime.tv_nsec = info->i_crtime.tv_nsec;
1190 }
1191
1192 return 0;
1193}
1194
1195static int shmem_setattr(struct mnt_idmap *idmap,
1196 struct dentry *dentry, struct iattr *attr)
1197{
1198 struct inode *inode = d_inode(dentry);
1199 struct shmem_inode_info *info = SHMEM_I(inode);
1200 int error;
1201 bool update_mtime = false;
1202 bool update_ctime = true;
1203
1204 error = setattr_prepare(idmap, dentry, attr);
1205 if (error)
1206 return error;
1207
1208 if ((info->seals & F_SEAL_EXEC) && (attr->ia_valid & ATTR_MODE)) {
1209 if ((inode->i_mode ^ attr->ia_mode) & 0111) {
1210 return -EPERM;
1211 }
1212 }
1213
1214 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1215 loff_t oldsize = inode->i_size;
1216 loff_t newsize = attr->ia_size;
1217
1218 /* protected by i_rwsem */
1219 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1220 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1221 return -EPERM;
1222
1223 if (newsize != oldsize) {
1224 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1225 oldsize, newsize);
1226 if (error)
1227 return error;
1228 i_size_write(inode, newsize);
1229 update_mtime = true;
1230 } else {
1231 update_ctime = false;
1232 }
1233 if (newsize <= oldsize) {
1234 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1235 if (oldsize > holebegin)
1236 unmap_mapping_range(inode->i_mapping,
1237 holebegin, 0, 1);
1238 if (info->alloced)
1239 shmem_truncate_range(inode,
1240 newsize, (loff_t)-1);
1241 /* unmap again to remove racily COWed private pages */
1242 if (oldsize > holebegin)
1243 unmap_mapping_range(inode->i_mapping,
1244 holebegin, 0, 1);
1245 }
1246 }
1247
1248 if (is_quota_modification(idmap, inode, attr)) {
1249 error = dquot_initialize(inode);
1250 if (error)
1251 return error;
1252 }
1253
1254 /* Transfer quota accounting */
1255 if (i_uid_needs_update(idmap, attr, inode) ||
1256 i_gid_needs_update(idmap, attr, inode)) {
1257 error = dquot_transfer(idmap, inode, attr);
1258 if (error)
1259 return error;
1260 }
1261
1262 setattr_copy(idmap, inode, attr);
1263 if (attr->ia_valid & ATTR_MODE)
1264 error = posix_acl_chmod(idmap, dentry, inode->i_mode);
1265 if (!error && update_ctime) {
1266 inode_set_ctime_current(inode);
1267 if (update_mtime)
1268 inode_set_mtime_to_ts(inode, inode_get_ctime(inode));
1269 inode_inc_iversion(inode);
1270 }
1271 return error;
1272}
1273
1274static void shmem_evict_inode(struct inode *inode)
1275{
1276 struct shmem_inode_info *info = SHMEM_I(inode);
1277 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1278 size_t freed = 0;
1279
1280 if (shmem_mapping(inode->i_mapping)) {
1281 shmem_unacct_size(info->flags, inode->i_size);
1282 inode->i_size = 0;
1283 mapping_set_exiting(inode->i_mapping);
1284 shmem_truncate_range(inode, 0, (loff_t)-1);
1285 if (!list_empty(&info->shrinklist)) {
1286 spin_lock(&sbinfo->shrinklist_lock);
1287 if (!list_empty(&info->shrinklist)) {
1288 list_del_init(&info->shrinklist);
1289 sbinfo->shrinklist_len--;
1290 }
1291 spin_unlock(&sbinfo->shrinklist_lock);
1292 }
1293 while (!list_empty(&info->swaplist)) {
1294 /* Wait while shmem_unuse() is scanning this inode... */
1295 wait_var_event(&info->stop_eviction,
1296 !atomic_read(&info->stop_eviction));
1297 mutex_lock(&shmem_swaplist_mutex);
1298 /* ...but beware of the race if we peeked too early */
1299 if (!atomic_read(&info->stop_eviction))
1300 list_del_init(&info->swaplist);
1301 mutex_unlock(&shmem_swaplist_mutex);
1302 }
1303 }
1304
1305 simple_xattrs_free(&info->xattrs, sbinfo->max_inodes ? &freed : NULL);
1306 shmem_free_inode(inode->i_sb, freed);
1307 WARN_ON(inode->i_blocks);
1308 clear_inode(inode);
1309#ifdef CONFIG_TMPFS_QUOTA
1310 dquot_free_inode(inode);
1311 dquot_drop(inode);
1312#endif
1313}
1314
1315static int shmem_find_swap_entries(struct address_space *mapping,
1316 pgoff_t start, struct folio_batch *fbatch,
1317 pgoff_t *indices, unsigned int type)
1318{
1319 XA_STATE(xas, &mapping->i_pages, start);
1320 struct folio *folio;
1321 swp_entry_t entry;
1322
1323 rcu_read_lock();
1324 xas_for_each(&xas, folio, ULONG_MAX) {
1325 if (xas_retry(&xas, folio))
1326 continue;
1327
1328 if (!xa_is_value(folio))
1329 continue;
1330
1331 entry = radix_to_swp_entry(folio);
1332 /*
1333 * swapin error entries can be found in the mapping. But they're
1334 * deliberately ignored here as we've done everything we can do.
1335 */
1336 if (swp_type(entry) != type)
1337 continue;
1338
1339 indices[folio_batch_count(fbatch)] = xas.xa_index;
1340 if (!folio_batch_add(fbatch, folio))
1341 break;
1342
1343 if (need_resched()) {
1344 xas_pause(&xas);
1345 cond_resched_rcu();
1346 }
1347 }
1348 rcu_read_unlock();
1349
1350 return xas.xa_index;
1351}
1352
1353/*
1354 * Move the swapped pages for an inode to page cache. Returns the count
1355 * of pages swapped in, or the error in case of failure.
1356 */
1357static int shmem_unuse_swap_entries(struct inode *inode,
1358 struct folio_batch *fbatch, pgoff_t *indices)
1359{
1360 int i = 0;
1361 int ret = 0;
1362 int error = 0;
1363 struct address_space *mapping = inode->i_mapping;
1364
1365 for (i = 0; i < folio_batch_count(fbatch); i++) {
1366 struct folio *folio = fbatch->folios[i];
1367
1368 if (!xa_is_value(folio))
1369 continue;
1370 error = shmem_swapin_folio(inode, indices[i], &folio, SGP_CACHE,
1371 mapping_gfp_mask(mapping), NULL, NULL);
1372 if (error == 0) {
1373 folio_unlock(folio);
1374 folio_put(folio);
1375 ret++;
1376 }
1377 if (error == -ENOMEM)
1378 break;
1379 error = 0;
1380 }
1381 return error ? error : ret;
1382}
1383
1384/*
1385 * If swap found in inode, free it and move page from swapcache to filecache.
1386 */
1387static int shmem_unuse_inode(struct inode *inode, unsigned int type)
1388{
1389 struct address_space *mapping = inode->i_mapping;
1390 pgoff_t start = 0;
1391 struct folio_batch fbatch;
1392 pgoff_t indices[PAGEVEC_SIZE];
1393 int ret = 0;
1394
1395 do {
1396 folio_batch_init(&fbatch);
1397 shmem_find_swap_entries(mapping, start, &fbatch, indices, type);
1398 if (folio_batch_count(&fbatch) == 0) {
1399 ret = 0;
1400 break;
1401 }
1402
1403 ret = shmem_unuse_swap_entries(inode, &fbatch, indices);
1404 if (ret < 0)
1405 break;
1406
1407 start = indices[folio_batch_count(&fbatch) - 1];
1408 } while (true);
1409
1410 return ret;
1411}
1412
1413/*
1414 * Read all the shared memory data that resides in the swap
1415 * device 'type' back into memory, so the swap device can be
1416 * unused.
1417 */
1418int shmem_unuse(unsigned int type)
1419{
1420 struct shmem_inode_info *info, *next;
1421 int error = 0;
1422
1423 if (list_empty(&shmem_swaplist))
1424 return 0;
1425
1426 mutex_lock(&shmem_swaplist_mutex);
1427 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1428 if (!info->swapped) {
1429 list_del_init(&info->swaplist);
1430 continue;
1431 }
1432 /*
1433 * Drop the swaplist mutex while searching the inode for swap;
1434 * but before doing so, make sure shmem_evict_inode() will not
1435 * remove placeholder inode from swaplist, nor let it be freed
1436 * (igrab() would protect from unlink, but not from unmount).
1437 */
1438 atomic_inc(&info->stop_eviction);
1439 mutex_unlock(&shmem_swaplist_mutex);
1440
1441 error = shmem_unuse_inode(&info->vfs_inode, type);
1442 cond_resched();
1443
1444 mutex_lock(&shmem_swaplist_mutex);
1445 next = list_next_entry(info, swaplist);
1446 if (!info->swapped)
1447 list_del_init(&info->swaplist);
1448 if (atomic_dec_and_test(&info->stop_eviction))
1449 wake_up_var(&info->stop_eviction);
1450 if (error)
1451 break;
1452 }
1453 mutex_unlock(&shmem_swaplist_mutex);
1454
1455 return error;
1456}
1457
1458/*
1459 * Move the page from the page cache to the swap cache.
1460 */
1461static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1462{
1463 struct folio *folio = page_folio(page);
1464 struct address_space *mapping = folio->mapping;
1465 struct inode *inode = mapping->host;
1466 struct shmem_inode_info *info = SHMEM_I(inode);
1467 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1468 swp_entry_t swap;
1469 pgoff_t index;
1470 int nr_pages;
1471 bool split = false;
1472
1473 /*
1474 * Our capabilities prevent regular writeback or sync from ever calling
1475 * shmem_writepage; but a stacking filesystem might use ->writepage of
1476 * its underlying filesystem, in which case tmpfs should write out to
1477 * swap only in response to memory pressure, and not for the writeback
1478 * threads or sync.
1479 */
1480 if (WARN_ON_ONCE(!wbc->for_reclaim))
1481 goto redirty;
1482
1483 if (WARN_ON_ONCE((info->flags & VM_LOCKED) || sbinfo->noswap))
1484 goto redirty;
1485
1486 if (!total_swap_pages)
1487 goto redirty;
1488
1489 /*
1490 * If CONFIG_THP_SWAP is not enabled, the large folio should be
1491 * split when swapping.
1492 *
1493 * And shrinkage of pages beyond i_size does not split swap, so
1494 * swapout of a large folio crossing i_size needs to split too
1495 * (unless fallocate has been used to preallocate beyond EOF).
1496 */
1497 if (folio_test_large(folio)) {
1498 index = shmem_fallocend(inode,
1499 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
1500 if ((index > folio->index && index < folio_next_index(folio)) ||
1501 !IS_ENABLED(CONFIG_THP_SWAP))
1502 split = true;
1503 }
1504
1505 if (split) {
1506try_split:
1507 /* Ensure the subpages are still dirty */
1508 folio_test_set_dirty(folio);
1509 if (split_huge_page_to_list_to_order(page, wbc->list, 0))
1510 goto redirty;
1511 folio = page_folio(page);
1512 folio_clear_dirty(folio);
1513 }
1514
1515 index = folio->index;
1516 nr_pages = folio_nr_pages(folio);
1517
1518 /*
1519 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1520 * value into swapfile.c, the only way we can correctly account for a
1521 * fallocated folio arriving here is now to initialize it and write it.
1522 *
1523 * That's okay for a folio already fallocated earlier, but if we have
1524 * not yet completed the fallocation, then (a) we want to keep track
1525 * of this folio in case we have to undo it, and (b) it may not be a
1526 * good idea to continue anyway, once we're pushing into swap. So
1527 * reactivate the folio, and let shmem_fallocate() quit when too many.
1528 */
1529 if (!folio_test_uptodate(folio)) {
1530 if (inode->i_private) {
1531 struct shmem_falloc *shmem_falloc;
1532 spin_lock(&inode->i_lock);
1533 shmem_falloc = inode->i_private;
1534 if (shmem_falloc &&
1535 !shmem_falloc->waitq &&
1536 index >= shmem_falloc->start &&
1537 index < shmem_falloc->next)
1538 shmem_falloc->nr_unswapped += nr_pages;
1539 else
1540 shmem_falloc = NULL;
1541 spin_unlock(&inode->i_lock);
1542 if (shmem_falloc)
1543 goto redirty;
1544 }
1545 folio_zero_range(folio, 0, folio_size(folio));
1546 flush_dcache_folio(folio);
1547 folio_mark_uptodate(folio);
1548 }
1549
1550 swap = folio_alloc_swap(folio);
1551 if (!swap.val) {
1552 if (nr_pages > 1)
1553 goto try_split;
1554
1555 goto redirty;
1556 }
1557
1558 /*
1559 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1560 * if it's not already there. Do it now before the folio is
1561 * moved to swap cache, when its pagelock no longer protects
1562 * the inode from eviction. But don't unlock the mutex until
1563 * we've incremented swapped, because shmem_unuse_inode() will
1564 * prune a !swapped inode from the swaplist under this mutex.
1565 */
1566 mutex_lock(&shmem_swaplist_mutex);
1567 if (list_empty(&info->swaplist))
1568 list_add(&info->swaplist, &shmem_swaplist);
1569
1570 if (add_to_swap_cache(folio, swap,
1571 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1572 NULL) == 0) {
1573 shmem_recalc_inode(inode, 0, nr_pages);
1574 swap_shmem_alloc(swap, nr_pages);
1575 shmem_delete_from_page_cache(folio, swp_to_radix_entry(swap));
1576
1577 mutex_unlock(&shmem_swaplist_mutex);
1578 BUG_ON(folio_mapped(folio));
1579 return swap_writepage(&folio->page, wbc);
1580 }
1581
1582 mutex_unlock(&shmem_swaplist_mutex);
1583 put_swap_folio(folio, swap);
1584redirty:
1585 folio_mark_dirty(folio);
1586 if (wbc->for_reclaim)
1587 return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */
1588 folio_unlock(folio);
1589 return 0;
1590}
1591
1592#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1593static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1594{
1595 char buffer[64];
1596
1597 if (!mpol || mpol->mode == MPOL_DEFAULT)
1598 return; /* show nothing */
1599
1600 mpol_to_str(buffer, sizeof(buffer), mpol);
1601
1602 seq_printf(seq, ",mpol=%s", buffer);
1603}
1604
1605static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1606{
1607 struct mempolicy *mpol = NULL;
1608 if (sbinfo->mpol) {
1609 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1610 mpol = sbinfo->mpol;
1611 mpol_get(mpol);
1612 raw_spin_unlock(&sbinfo->stat_lock);
1613 }
1614 return mpol;
1615}
1616#else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1617static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1618{
1619}
1620static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1621{
1622 return NULL;
1623}
1624#endif /* CONFIG_NUMA && CONFIG_TMPFS */
1625
1626static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
1627 pgoff_t index, unsigned int order, pgoff_t *ilx);
1628
1629static struct folio *shmem_swapin_cluster(swp_entry_t swap, gfp_t gfp,
1630 struct shmem_inode_info *info, pgoff_t index)
1631{
1632 struct mempolicy *mpol;
1633 pgoff_t ilx;
1634 struct folio *folio;
1635
1636 mpol = shmem_get_pgoff_policy(info, index, 0, &ilx);
1637 folio = swap_cluster_readahead(swap, gfp, mpol, ilx);
1638 mpol_cond_put(mpol);
1639
1640 return folio;
1641}
1642
1643/*
1644 * Make sure huge_gfp is always more limited than limit_gfp.
1645 * Some of the flags set permissions, while others set limitations.
1646 */
1647static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1648{
1649 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1650 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1651 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1652 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1653
1654 /* Allow allocations only from the originally specified zones. */
1655 result |= zoneflags;
1656
1657 /*
1658 * Minimize the result gfp by taking the union with the deny flags,
1659 * and the intersection of the allow flags.
1660 */
1661 result |= (limit_gfp & denyflags);
1662 result |= (huge_gfp & limit_gfp) & allowflags;
1663
1664 return result;
1665}
1666
1667#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1668bool shmem_hpage_pmd_enabled(void)
1669{
1670 if (shmem_huge == SHMEM_HUGE_DENY)
1671 return false;
1672 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_always))
1673 return true;
1674 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_madvise))
1675 return true;
1676 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_within_size))
1677 return true;
1678 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_inherit) &&
1679 shmem_huge != SHMEM_HUGE_NEVER)
1680 return true;
1681
1682 return false;
1683}
1684
1685unsigned long shmem_allowable_huge_orders(struct inode *inode,
1686 struct vm_area_struct *vma, pgoff_t index,
1687 loff_t write_end, bool shmem_huge_force)
1688{
1689 unsigned long mask = READ_ONCE(huge_shmem_orders_always);
1690 unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
1691 unsigned long vm_flags = vma ? vma->vm_flags : 0;
1692 pgoff_t aligned_index;
1693 bool global_huge;
1694 loff_t i_size;
1695 int order;
1696
1697 if (thp_disabled_by_hw() || (vma && vma_thp_disabled(vma, vm_flags)))
1698 return 0;
1699
1700 global_huge = shmem_huge_global_enabled(inode, index, write_end,
1701 shmem_huge_force, vm_flags);
1702 if (!vma || !vma_is_anon_shmem(vma)) {
1703 /*
1704 * For tmpfs, we now only support PMD sized THP if huge page
1705 * is enabled, otherwise fallback to order 0.
1706 */
1707 return global_huge ? BIT(HPAGE_PMD_ORDER) : 0;
1708 }
1709
1710 /*
1711 * Following the 'deny' semantics of the top level, force the huge
1712 * option off from all mounts.
1713 */
1714 if (shmem_huge == SHMEM_HUGE_DENY)
1715 return 0;
1716
1717 /*
1718 * Only allow inherit orders if the top-level value is 'force', which
1719 * means non-PMD sized THP can not override 'huge' mount option now.
1720 */
1721 if (shmem_huge == SHMEM_HUGE_FORCE)
1722 return READ_ONCE(huge_shmem_orders_inherit);
1723
1724 /* Allow mTHP that will be fully within i_size. */
1725 order = highest_order(within_size_orders);
1726 while (within_size_orders) {
1727 aligned_index = round_up(index + 1, 1 << order);
1728 i_size = round_up(i_size_read(inode), PAGE_SIZE);
1729 if (i_size >> PAGE_SHIFT >= aligned_index) {
1730 mask |= within_size_orders;
1731 break;
1732 }
1733
1734 order = next_order(&within_size_orders, order);
1735 }
1736
1737 if (vm_flags & VM_HUGEPAGE)
1738 mask |= READ_ONCE(huge_shmem_orders_madvise);
1739
1740 if (global_huge)
1741 mask |= READ_ONCE(huge_shmem_orders_inherit);
1742
1743 return THP_ORDERS_ALL_FILE_DEFAULT & mask;
1744}
1745
1746static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault *vmf,
1747 struct address_space *mapping, pgoff_t index,
1748 unsigned long orders)
1749{
1750 struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
1751 pgoff_t aligned_index;
1752 unsigned long pages;
1753 int order;
1754
1755 if (vma) {
1756 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
1757 if (!orders)
1758 return 0;
1759 }
1760
1761 /* Find the highest order that can add into the page cache */
1762 order = highest_order(orders);
1763 while (orders) {
1764 pages = 1UL << order;
1765 aligned_index = round_down(index, pages);
1766 /*
1767 * Check for conflict before waiting on a huge allocation.
1768 * Conflict might be that a huge page has just been allocated
1769 * and added to page cache by a racing thread, or that there
1770 * is already at least one small page in the huge extent.
1771 * Be careful to retry when appropriate, but not forever!
1772 * Elsewhere -EEXIST would be the right code, but not here.
1773 */
1774 if (!xa_find(&mapping->i_pages, &aligned_index,
1775 aligned_index + pages - 1, XA_PRESENT))
1776 break;
1777 order = next_order(&orders, order);
1778 }
1779
1780 return orders;
1781}
1782#else
1783static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault *vmf,
1784 struct address_space *mapping, pgoff_t index,
1785 unsigned long orders)
1786{
1787 return 0;
1788}
1789#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
1790
1791static struct folio *shmem_alloc_folio(gfp_t gfp, int order,
1792 struct shmem_inode_info *info, pgoff_t index)
1793{
1794 struct mempolicy *mpol;
1795 pgoff_t ilx;
1796 struct folio *folio;
1797
1798 mpol = shmem_get_pgoff_policy(info, index, order, &ilx);
1799 folio = folio_alloc_mpol(gfp, order, mpol, ilx, numa_node_id());
1800 mpol_cond_put(mpol);
1801
1802 return folio;
1803}
1804
1805static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
1806 gfp_t gfp, struct inode *inode, pgoff_t index,
1807 struct mm_struct *fault_mm, unsigned long orders)
1808{
1809 struct address_space *mapping = inode->i_mapping;
1810 struct shmem_inode_info *info = SHMEM_I(inode);
1811 unsigned long suitable_orders = 0;
1812 struct folio *folio = NULL;
1813 long pages;
1814 int error, order;
1815
1816 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1817 orders = 0;
1818
1819 if (orders > 0) {
1820 suitable_orders = shmem_suitable_orders(inode, vmf,
1821 mapping, index, orders);
1822
1823 order = highest_order(suitable_orders);
1824 while (suitable_orders) {
1825 pages = 1UL << order;
1826 index = round_down(index, pages);
1827 folio = shmem_alloc_folio(gfp, order, info, index);
1828 if (folio)
1829 goto allocated;
1830
1831 if (pages == HPAGE_PMD_NR)
1832 count_vm_event(THP_FILE_FALLBACK);
1833 count_mthp_stat(order, MTHP_STAT_SHMEM_FALLBACK);
1834 order = next_order(&suitable_orders, order);
1835 }
1836 } else {
1837 pages = 1;
1838 folio = shmem_alloc_folio(gfp, 0, info, index);
1839 }
1840 if (!folio)
1841 return ERR_PTR(-ENOMEM);
1842
1843allocated:
1844 __folio_set_locked(folio);
1845 __folio_set_swapbacked(folio);
1846
1847 gfp &= GFP_RECLAIM_MASK;
1848 error = mem_cgroup_charge(folio, fault_mm, gfp);
1849 if (error) {
1850 if (xa_find(&mapping->i_pages, &index,
1851 index + pages - 1, XA_PRESENT)) {
1852 error = -EEXIST;
1853 } else if (pages > 1) {
1854 if (pages == HPAGE_PMD_NR) {
1855 count_vm_event(THP_FILE_FALLBACK);
1856 count_vm_event(THP_FILE_FALLBACK_CHARGE);
1857 }
1858 count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK);
1859 count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK_CHARGE);
1860 }
1861 goto unlock;
1862 }
1863
1864 error = shmem_add_to_page_cache(folio, mapping, index, NULL, gfp);
1865 if (error)
1866 goto unlock;
1867
1868 error = shmem_inode_acct_blocks(inode, pages);
1869 if (error) {
1870 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1871 long freed;
1872 /*
1873 * Try to reclaim some space by splitting a few
1874 * large folios beyond i_size on the filesystem.
1875 */
1876 shmem_unused_huge_shrink(sbinfo, NULL, pages);
1877 /*
1878 * And do a shmem_recalc_inode() to account for freed pages:
1879 * except our folio is there in cache, so not quite balanced.
1880 */
1881 spin_lock(&info->lock);
1882 freed = pages + info->alloced - info->swapped -
1883 READ_ONCE(mapping->nrpages);
1884 if (freed > 0)
1885 info->alloced -= freed;
1886 spin_unlock(&info->lock);
1887 if (freed > 0)
1888 shmem_inode_unacct_blocks(inode, freed);
1889 error = shmem_inode_acct_blocks(inode, pages);
1890 if (error) {
1891 filemap_remove_folio(folio);
1892 goto unlock;
1893 }
1894 }
1895
1896 shmem_recalc_inode(inode, pages, 0);
1897 folio_add_lru(folio);
1898 return folio;
1899
1900unlock:
1901 folio_unlock(folio);
1902 folio_put(folio);
1903 return ERR_PTR(error);
1904}
1905
1906/*
1907 * When a page is moved from swapcache to shmem filecache (either by the
1908 * usual swapin of shmem_get_folio_gfp(), or by the less common swapoff of
1909 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1910 * ignorance of the mapping it belongs to. If that mapping has special
1911 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1912 * we may need to copy to a suitable page before moving to filecache.
1913 *
1914 * In a future release, this may well be extended to respect cpuset and
1915 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1916 * but for now it is a simple matter of zone.
1917 */
1918static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
1919{
1920 return folio_zonenum(folio) > gfp_zone(gfp);
1921}
1922
1923static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
1924 struct shmem_inode_info *info, pgoff_t index,
1925 struct vm_area_struct *vma)
1926{
1927 struct folio *new, *old = *foliop;
1928 swp_entry_t entry = old->swap;
1929 struct address_space *swap_mapping = swap_address_space(entry);
1930 pgoff_t swap_index = swap_cache_index(entry);
1931 XA_STATE(xas, &swap_mapping->i_pages, swap_index);
1932 int nr_pages = folio_nr_pages(old);
1933 int error = 0, i;
1934
1935 /*
1936 * We have arrived here because our zones are constrained, so don't
1937 * limit chance of success by further cpuset and node constraints.
1938 */
1939 gfp &= ~GFP_CONSTRAINT_MASK;
1940#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1941 if (nr_pages > 1) {
1942 gfp_t huge_gfp = vma_thp_gfp_mask(vma);
1943
1944 gfp = limit_gfp_mask(huge_gfp, gfp);
1945 }
1946#endif
1947
1948 new = shmem_alloc_folio(gfp, folio_order(old), info, index);
1949 if (!new)
1950 return -ENOMEM;
1951
1952 folio_ref_add(new, nr_pages);
1953 folio_copy(new, old);
1954 flush_dcache_folio(new);
1955
1956 __folio_set_locked(new);
1957 __folio_set_swapbacked(new);
1958 folio_mark_uptodate(new);
1959 new->swap = entry;
1960 folio_set_swapcache(new);
1961
1962 /* Swap cache still stores N entries instead of a high-order entry */
1963 xa_lock_irq(&swap_mapping->i_pages);
1964 for (i = 0; i < nr_pages; i++) {
1965 void *item = xas_load(&xas);
1966
1967 if (item != old) {
1968 error = -ENOENT;
1969 break;
1970 }
1971
1972 xas_store(&xas, new);
1973 xas_next(&xas);
1974 }
1975 if (!error) {
1976 mem_cgroup_replace_folio(old, new);
1977 shmem_update_stats(new, nr_pages);
1978 shmem_update_stats(old, -nr_pages);
1979 }
1980 xa_unlock_irq(&swap_mapping->i_pages);
1981
1982 if (unlikely(error)) {
1983 /*
1984 * Is this possible? I think not, now that our callers
1985 * check both the swapcache flag and folio->private
1986 * after getting the folio lock; but be defensive.
1987 * Reverse old to newpage for clear and free.
1988 */
1989 old = new;
1990 } else {
1991 folio_add_lru(new);
1992 *foliop = new;
1993 }
1994
1995 folio_clear_swapcache(old);
1996 old->private = NULL;
1997
1998 folio_unlock(old);
1999 /*
2000 * The old folio are removed from swap cache, drop the 'nr_pages'
2001 * reference, as well as one temporary reference getting from swap
2002 * cache.
2003 */
2004 folio_put_refs(old, nr_pages + 1);
2005 return error;
2006}
2007
2008static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
2009 struct folio *folio, swp_entry_t swap)
2010{
2011 struct address_space *mapping = inode->i_mapping;
2012 swp_entry_t swapin_error;
2013 void *old;
2014 int nr_pages;
2015
2016 swapin_error = make_poisoned_swp_entry();
2017 old = xa_cmpxchg_irq(&mapping->i_pages, index,
2018 swp_to_radix_entry(swap),
2019 swp_to_radix_entry(swapin_error), 0);
2020 if (old != swp_to_radix_entry(swap))
2021 return;
2022
2023 nr_pages = folio_nr_pages(folio);
2024 folio_wait_writeback(folio);
2025 delete_from_swap_cache(folio);
2026 /*
2027 * Don't treat swapin error folio as alloced. Otherwise inode->i_blocks
2028 * won't be 0 when inode is released and thus trigger WARN_ON(i_blocks)
2029 * in shmem_evict_inode().
2030 */
2031 shmem_recalc_inode(inode, -nr_pages, -nr_pages);
2032 swap_free_nr(swap, nr_pages);
2033}
2034
2035static int shmem_split_large_entry(struct inode *inode, pgoff_t index,
2036 swp_entry_t swap, gfp_t gfp)
2037{
2038 struct address_space *mapping = inode->i_mapping;
2039 XA_STATE_ORDER(xas, &mapping->i_pages, index, 0);
2040 void *alloced_shadow = NULL;
2041 int alloced_order = 0, i;
2042
2043 /* Convert user data gfp flags to xarray node gfp flags */
2044 gfp &= GFP_RECLAIM_MASK;
2045
2046 for (;;) {
2047 int order = -1, split_order = 0;
2048 void *old = NULL;
2049
2050 xas_lock_irq(&xas);
2051 old = xas_load(&xas);
2052 if (!xa_is_value(old) || swp_to_radix_entry(swap) != old) {
2053 xas_set_err(&xas, -EEXIST);
2054 goto unlock;
2055 }
2056
2057 order = xas_get_order(&xas);
2058
2059 /* Swap entry may have changed before we re-acquire the lock */
2060 if (alloced_order &&
2061 (old != alloced_shadow || order != alloced_order)) {
2062 xas_destroy(&xas);
2063 alloced_order = 0;
2064 }
2065
2066 /* Try to split large swap entry in pagecache */
2067 if (order > 0) {
2068 if (!alloced_order) {
2069 split_order = order;
2070 goto unlock;
2071 }
2072 xas_split(&xas, old, order);
2073
2074 /*
2075 * Re-set the swap entry after splitting, and the swap
2076 * offset of the original large entry must be continuous.
2077 */
2078 for (i = 0; i < 1 << order; i++) {
2079 pgoff_t aligned_index = round_down(index, 1 << order);
2080 swp_entry_t tmp;
2081
2082 tmp = swp_entry(swp_type(swap), swp_offset(swap) + i);
2083 __xa_store(&mapping->i_pages, aligned_index + i,
2084 swp_to_radix_entry(tmp), 0);
2085 }
2086 }
2087
2088unlock:
2089 xas_unlock_irq(&xas);
2090
2091 /* split needed, alloc here and retry. */
2092 if (split_order) {
2093 xas_split_alloc(&xas, old, split_order, gfp);
2094 if (xas_error(&xas))
2095 goto error;
2096 alloced_shadow = old;
2097 alloced_order = split_order;
2098 xas_reset(&xas);
2099 continue;
2100 }
2101
2102 if (!xas_nomem(&xas, gfp))
2103 break;
2104 }
2105
2106error:
2107 if (xas_error(&xas))
2108 return xas_error(&xas);
2109
2110 return alloced_order;
2111}
2112
2113/*
2114 * Swap in the folio pointed to by *foliop.
2115 * Caller has to make sure that *foliop contains a valid swapped folio.
2116 * Returns 0 and the folio in foliop if success. On failure, returns the
2117 * error code and NULL in *foliop.
2118 */
2119static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
2120 struct folio **foliop, enum sgp_type sgp,
2121 gfp_t gfp, struct vm_area_struct *vma,
2122 vm_fault_t *fault_type)
2123{
2124 struct address_space *mapping = inode->i_mapping;
2125 struct mm_struct *fault_mm = vma ? vma->vm_mm : NULL;
2126 struct shmem_inode_info *info = SHMEM_I(inode);
2127 struct swap_info_struct *si;
2128 struct folio *folio = NULL;
2129 swp_entry_t swap;
2130 int error, nr_pages;
2131
2132 VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
2133 swap = radix_to_swp_entry(*foliop);
2134 *foliop = NULL;
2135
2136 if (is_poisoned_swp_entry(swap))
2137 return -EIO;
2138
2139 si = get_swap_device(swap);
2140 if (!si) {
2141 if (!shmem_confirm_swap(mapping, index, swap))
2142 return -EEXIST;
2143 else
2144 return -EINVAL;
2145 }
2146
2147 /* Look it up and read it in.. */
2148 folio = swap_cache_get_folio(swap, NULL, 0);
2149 if (!folio) {
2150 int split_order;
2151
2152 /* Or update major stats only when swapin succeeds?? */
2153 if (fault_type) {
2154 *fault_type |= VM_FAULT_MAJOR;
2155 count_vm_event(PGMAJFAULT);
2156 count_memcg_event_mm(fault_mm, PGMAJFAULT);
2157 }
2158
2159 /*
2160 * Now swap device can only swap in order 0 folio, then we
2161 * should split the large swap entry stored in the pagecache
2162 * if necessary.
2163 */
2164 split_order = shmem_split_large_entry(inode, index, swap, gfp);
2165 if (split_order < 0) {
2166 error = split_order;
2167 goto failed;
2168 }
2169
2170 /*
2171 * If the large swap entry has already been split, it is
2172 * necessary to recalculate the new swap entry based on
2173 * the old order alignment.
2174 */
2175 if (split_order > 0) {
2176 pgoff_t offset = index - round_down(index, 1 << split_order);
2177
2178 swap = swp_entry(swp_type(swap), swp_offset(swap) + offset);
2179 }
2180
2181 /* Here we actually start the io */
2182 folio = shmem_swapin_cluster(swap, gfp, info, index);
2183 if (!folio) {
2184 error = -ENOMEM;
2185 goto failed;
2186 }
2187 }
2188
2189 /* We have to do this with folio locked to prevent races */
2190 folio_lock(folio);
2191 if (!folio_test_swapcache(folio) ||
2192 folio->swap.val != swap.val ||
2193 !shmem_confirm_swap(mapping, index, swap)) {
2194 error = -EEXIST;
2195 goto unlock;
2196 }
2197 if (!folio_test_uptodate(folio)) {
2198 error = -EIO;
2199 goto failed;
2200 }
2201 folio_wait_writeback(folio);
2202 nr_pages = folio_nr_pages(folio);
2203
2204 /*
2205 * Some architectures may have to restore extra metadata to the
2206 * folio after reading from swap.
2207 */
2208 arch_swap_restore(folio_swap(swap, folio), folio);
2209
2210 if (shmem_should_replace_folio(folio, gfp)) {
2211 error = shmem_replace_folio(&folio, gfp, info, index, vma);
2212 if (error)
2213 goto failed;
2214 }
2215
2216 error = shmem_add_to_page_cache(folio, mapping,
2217 round_down(index, nr_pages),
2218 swp_to_radix_entry(swap), gfp);
2219 if (error)
2220 goto failed;
2221
2222 shmem_recalc_inode(inode, 0, -nr_pages);
2223
2224 if (sgp == SGP_WRITE)
2225 folio_mark_accessed(folio);
2226
2227 delete_from_swap_cache(folio);
2228 folio_mark_dirty(folio);
2229 swap_free_nr(swap, nr_pages);
2230 put_swap_device(si);
2231
2232 *foliop = folio;
2233 return 0;
2234failed:
2235 if (!shmem_confirm_swap(mapping, index, swap))
2236 error = -EEXIST;
2237 if (error == -EIO)
2238 shmem_set_folio_swapin_error(inode, index, folio, swap);
2239unlock:
2240 if (folio) {
2241 folio_unlock(folio);
2242 folio_put(folio);
2243 }
2244 put_swap_device(si);
2245
2246 return error;
2247}
2248
2249/*
2250 * shmem_get_folio_gfp - find page in cache, or get from swap, or allocate
2251 *
2252 * If we allocate a new one we do not mark it dirty. That's up to the
2253 * vm. If we swap it in we mark it dirty since we also free the swap
2254 * entry since a page cannot live in both the swap and page cache.
2255 *
2256 * vmf and fault_type are only supplied by shmem_fault: otherwise they are NULL.
2257 */
2258static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
2259 loff_t write_end, struct folio **foliop, enum sgp_type sgp,
2260 gfp_t gfp, struct vm_fault *vmf, vm_fault_t *fault_type)
2261{
2262 struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
2263 struct mm_struct *fault_mm;
2264 struct folio *folio;
2265 int error;
2266 bool alloced;
2267 unsigned long orders = 0;
2268
2269 if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
2270 return -EINVAL;
2271
2272 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
2273 return -EFBIG;
2274repeat:
2275 if (sgp <= SGP_CACHE &&
2276 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode))
2277 return -EINVAL;
2278
2279 alloced = false;
2280 fault_mm = vma ? vma->vm_mm : NULL;
2281
2282 folio = filemap_get_entry(inode->i_mapping, index);
2283 if (folio && vma && userfaultfd_minor(vma)) {
2284 if (!xa_is_value(folio))
2285 folio_put(folio);
2286 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
2287 return 0;
2288 }
2289
2290 if (xa_is_value(folio)) {
2291 error = shmem_swapin_folio(inode, index, &folio,
2292 sgp, gfp, vma, fault_type);
2293 if (error == -EEXIST)
2294 goto repeat;
2295
2296 *foliop = folio;
2297 return error;
2298 }
2299
2300 if (folio) {
2301 folio_lock(folio);
2302
2303 /* Has the folio been truncated or swapped out? */
2304 if (unlikely(folio->mapping != inode->i_mapping)) {
2305 folio_unlock(folio);
2306 folio_put(folio);
2307 goto repeat;
2308 }
2309 if (sgp == SGP_WRITE)
2310 folio_mark_accessed(folio);
2311 if (folio_test_uptodate(folio))
2312 goto out;
2313 /* fallocated folio */
2314 if (sgp != SGP_READ)
2315 goto clear;
2316 folio_unlock(folio);
2317 folio_put(folio);
2318 }
2319
2320 /*
2321 * SGP_READ: succeed on hole, with NULL folio, letting caller zero.
2322 * SGP_NOALLOC: fail on hole, with NULL folio, letting caller fail.
2323 */
2324 *foliop = NULL;
2325 if (sgp == SGP_READ)
2326 return 0;
2327 if (sgp == SGP_NOALLOC)
2328 return -ENOENT;
2329
2330 /*
2331 * Fast cache lookup and swap lookup did not find it: allocate.
2332 */
2333
2334 if (vma && userfaultfd_missing(vma)) {
2335 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
2336 return 0;
2337 }
2338
2339 /* Find hugepage orders that are allowed for anonymous shmem and tmpfs. */
2340 orders = shmem_allowable_huge_orders(inode, vma, index, write_end, false);
2341 if (orders > 0) {
2342 gfp_t huge_gfp;
2343
2344 huge_gfp = vma_thp_gfp_mask(vma);
2345 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
2346 folio = shmem_alloc_and_add_folio(vmf, huge_gfp,
2347 inode, index, fault_mm, orders);
2348 if (!IS_ERR(folio)) {
2349 if (folio_test_pmd_mappable(folio))
2350 count_vm_event(THP_FILE_ALLOC);
2351 count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_ALLOC);
2352 goto alloced;
2353 }
2354 if (PTR_ERR(folio) == -EEXIST)
2355 goto repeat;
2356 }
2357
2358 folio = shmem_alloc_and_add_folio(vmf, gfp, inode, index, fault_mm, 0);
2359 if (IS_ERR(folio)) {
2360 error = PTR_ERR(folio);
2361 if (error == -EEXIST)
2362 goto repeat;
2363 folio = NULL;
2364 goto unlock;
2365 }
2366
2367alloced:
2368 alloced = true;
2369 if (folio_test_large(folio) &&
2370 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
2371 folio_next_index(folio)) {
2372 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2373 struct shmem_inode_info *info = SHMEM_I(inode);
2374 /*
2375 * Part of the large folio is beyond i_size: subject
2376 * to shrink under memory pressure.
2377 */
2378 spin_lock(&sbinfo->shrinklist_lock);
2379 /*
2380 * _careful to defend against unlocked access to
2381 * ->shrink_list in shmem_unused_huge_shrink()
2382 */
2383 if (list_empty_careful(&info->shrinklist)) {
2384 list_add_tail(&info->shrinklist,
2385 &sbinfo->shrinklist);
2386 sbinfo->shrinklist_len++;
2387 }
2388 spin_unlock(&sbinfo->shrinklist_lock);
2389 }
2390
2391 if (sgp == SGP_WRITE)
2392 folio_set_referenced(folio);
2393 /*
2394 * Let SGP_FALLOC use the SGP_WRITE optimization on a new folio.
2395 */
2396 if (sgp == SGP_FALLOC)
2397 sgp = SGP_WRITE;
2398clear:
2399 /*
2400 * Let SGP_WRITE caller clear ends if write does not fill folio;
2401 * but SGP_FALLOC on a folio fallocated earlier must initialize
2402 * it now, lest undo on failure cancel our earlier guarantee.
2403 */
2404 if (sgp != SGP_WRITE && !folio_test_uptodate(folio)) {
2405 long i, n = folio_nr_pages(folio);
2406
2407 for (i = 0; i < n; i++)
2408 clear_highpage(folio_page(folio, i));
2409 flush_dcache_folio(folio);
2410 folio_mark_uptodate(folio);
2411 }
2412
2413 /* Perhaps the file has been truncated since we checked */
2414 if (sgp <= SGP_CACHE &&
2415 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
2416 error = -EINVAL;
2417 goto unlock;
2418 }
2419out:
2420 *foliop = folio;
2421 return 0;
2422
2423 /*
2424 * Error recovery.
2425 */
2426unlock:
2427 if (alloced)
2428 filemap_remove_folio(folio);
2429 shmem_recalc_inode(inode, 0, 0);
2430 if (folio) {
2431 folio_unlock(folio);
2432 folio_put(folio);
2433 }
2434 return error;
2435}
2436
2437/**
2438 * shmem_get_folio - find, and lock a shmem folio.
2439 * @inode: inode to search
2440 * @index: the page index.
2441 * @write_end: end of a write, could extend inode size
2442 * @foliop: pointer to the folio if found
2443 * @sgp: SGP_* flags to control behavior
2444 *
2445 * Looks up the page cache entry at @inode & @index. If a folio is
2446 * present, it is returned locked with an increased refcount.
2447 *
2448 * If the caller modifies data in the folio, it must call folio_mark_dirty()
2449 * before unlocking the folio to ensure that the folio is not reclaimed.
2450 * There is no need to reserve space before calling folio_mark_dirty().
2451 *
2452 * When no folio is found, the behavior depends on @sgp:
2453 * - for SGP_READ, *@foliop is %NULL and 0 is returned
2454 * - for SGP_NOALLOC, *@foliop is %NULL and -ENOENT is returned
2455 * - for all other flags a new folio is allocated, inserted into the
2456 * page cache and returned locked in @foliop.
2457 *
2458 * Context: May sleep.
2459 * Return: 0 if successful, else a negative error code.
2460 */
2461int shmem_get_folio(struct inode *inode, pgoff_t index, loff_t write_end,
2462 struct folio **foliop, enum sgp_type sgp)
2463{
2464 return shmem_get_folio_gfp(inode, index, write_end, foliop, sgp,
2465 mapping_gfp_mask(inode->i_mapping), NULL, NULL);
2466}
2467EXPORT_SYMBOL_GPL(shmem_get_folio);
2468
2469/*
2470 * This is like autoremove_wake_function, but it removes the wait queue
2471 * entry unconditionally - even if something else had already woken the
2472 * target.
2473 */
2474static int synchronous_wake_function(wait_queue_entry_t *wait,
2475 unsigned int mode, int sync, void *key)
2476{
2477 int ret = default_wake_function(wait, mode, sync, key);
2478 list_del_init(&wait->entry);
2479 return ret;
2480}
2481
2482/*
2483 * Trinity finds that probing a hole which tmpfs is punching can
2484 * prevent the hole-punch from ever completing: which in turn
2485 * locks writers out with its hold on i_rwsem. So refrain from
2486 * faulting pages into the hole while it's being punched. Although
2487 * shmem_undo_range() does remove the additions, it may be unable to
2488 * keep up, as each new page needs its own unmap_mapping_range() call,
2489 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2490 *
2491 * It does not matter if we sometimes reach this check just before the
2492 * hole-punch begins, so that one fault then races with the punch:
2493 * we just need to make racing faults a rare case.
2494 *
2495 * The implementation below would be much simpler if we just used a
2496 * standard mutex or completion: but we cannot take i_rwsem in fault,
2497 * and bloating every shmem inode for this unlikely case would be sad.
2498 */
2499static vm_fault_t shmem_falloc_wait(struct vm_fault *vmf, struct inode *inode)
2500{
2501 struct shmem_falloc *shmem_falloc;
2502 struct file *fpin = NULL;
2503 vm_fault_t ret = 0;
2504
2505 spin_lock(&inode->i_lock);
2506 shmem_falloc = inode->i_private;
2507 if (shmem_falloc &&
2508 shmem_falloc->waitq &&
2509 vmf->pgoff >= shmem_falloc->start &&
2510 vmf->pgoff < shmem_falloc->next) {
2511 wait_queue_head_t *shmem_falloc_waitq;
2512 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2513
2514 ret = VM_FAULT_NOPAGE;
2515 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2516 shmem_falloc_waitq = shmem_falloc->waitq;
2517 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2518 TASK_UNINTERRUPTIBLE);
2519 spin_unlock(&inode->i_lock);
2520 schedule();
2521
2522 /*
2523 * shmem_falloc_waitq points into the shmem_fallocate()
2524 * stack of the hole-punching task: shmem_falloc_waitq
2525 * is usually invalid by the time we reach here, but
2526 * finish_wait() does not dereference it in that case;
2527 * though i_lock needed lest racing with wake_up_all().
2528 */
2529 spin_lock(&inode->i_lock);
2530 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2531 }
2532 spin_unlock(&inode->i_lock);
2533 if (fpin) {
2534 fput(fpin);
2535 ret = VM_FAULT_RETRY;
2536 }
2537 return ret;
2538}
2539
2540static vm_fault_t shmem_fault(struct vm_fault *vmf)
2541{
2542 struct inode *inode = file_inode(vmf->vma->vm_file);
2543 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2544 struct folio *folio = NULL;
2545 vm_fault_t ret = 0;
2546 int err;
2547
2548 /*
2549 * Trinity finds that probing a hole which tmpfs is punching can
2550 * prevent the hole-punch from ever completing: noted in i_private.
2551 */
2552 if (unlikely(inode->i_private)) {
2553 ret = shmem_falloc_wait(vmf, inode);
2554 if (ret)
2555 return ret;
2556 }
2557
2558 WARN_ON_ONCE(vmf->page != NULL);
2559 err = shmem_get_folio_gfp(inode, vmf->pgoff, 0, &folio, SGP_CACHE,
2560 gfp, vmf, &ret);
2561 if (err)
2562 return vmf_error(err);
2563 if (folio) {
2564 vmf->page = folio_file_page(folio, vmf->pgoff);
2565 ret |= VM_FAULT_LOCKED;
2566 }
2567 return ret;
2568}
2569
2570unsigned long shmem_get_unmapped_area(struct file *file,
2571 unsigned long uaddr, unsigned long len,
2572 unsigned long pgoff, unsigned long flags)
2573{
2574 unsigned long addr;
2575 unsigned long offset;
2576 unsigned long inflated_len;
2577 unsigned long inflated_addr;
2578 unsigned long inflated_offset;
2579 unsigned long hpage_size;
2580
2581 if (len > TASK_SIZE)
2582 return -ENOMEM;
2583
2584 addr = mm_get_unmapped_area(current->mm, file, uaddr, len, pgoff,
2585 flags);
2586
2587 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2588 return addr;
2589 if (IS_ERR_VALUE(addr))
2590 return addr;
2591 if (addr & ~PAGE_MASK)
2592 return addr;
2593 if (addr > TASK_SIZE - len)
2594 return addr;
2595
2596 if (shmem_huge == SHMEM_HUGE_DENY)
2597 return addr;
2598 if (flags & MAP_FIXED)
2599 return addr;
2600 /*
2601 * Our priority is to support MAP_SHARED mapped hugely;
2602 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2603 * But if caller specified an address hint and we allocated area there
2604 * successfully, respect that as before.
2605 */
2606 if (uaddr == addr)
2607 return addr;
2608
2609 hpage_size = HPAGE_PMD_SIZE;
2610 if (shmem_huge != SHMEM_HUGE_FORCE) {
2611 struct super_block *sb;
2612 unsigned long __maybe_unused hpage_orders;
2613 int order = 0;
2614
2615 if (file) {
2616 VM_BUG_ON(file->f_op != &shmem_file_operations);
2617 sb = file_inode(file)->i_sb;
2618 } else {
2619 /*
2620 * Called directly from mm/mmap.c, or drivers/char/mem.c
2621 * for "/dev/zero", to create a shared anonymous object.
2622 */
2623 if (IS_ERR(shm_mnt))
2624 return addr;
2625 sb = shm_mnt->mnt_sb;
2626
2627 /*
2628 * Find the highest mTHP order used for anonymous shmem to
2629 * provide a suitable alignment address.
2630 */
2631#ifdef CONFIG_TRANSPARENT_HUGEPAGE
2632 hpage_orders = READ_ONCE(huge_shmem_orders_always);
2633 hpage_orders |= READ_ONCE(huge_shmem_orders_within_size);
2634 hpage_orders |= READ_ONCE(huge_shmem_orders_madvise);
2635 if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER)
2636 hpage_orders |= READ_ONCE(huge_shmem_orders_inherit);
2637
2638 if (hpage_orders > 0) {
2639 order = highest_order(hpage_orders);
2640 hpage_size = PAGE_SIZE << order;
2641 }
2642#endif
2643 }
2644 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER && !order)
2645 return addr;
2646 }
2647
2648 if (len < hpage_size)
2649 return addr;
2650
2651 offset = (pgoff << PAGE_SHIFT) & (hpage_size - 1);
2652 if (offset && offset + len < 2 * hpage_size)
2653 return addr;
2654 if ((addr & (hpage_size - 1)) == offset)
2655 return addr;
2656
2657 inflated_len = len + hpage_size - PAGE_SIZE;
2658 if (inflated_len > TASK_SIZE)
2659 return addr;
2660 if (inflated_len < len)
2661 return addr;
2662
2663 inflated_addr = mm_get_unmapped_area(current->mm, NULL, uaddr,
2664 inflated_len, 0, flags);
2665 if (IS_ERR_VALUE(inflated_addr))
2666 return addr;
2667 if (inflated_addr & ~PAGE_MASK)
2668 return addr;
2669
2670 inflated_offset = inflated_addr & (hpage_size - 1);
2671 inflated_addr += offset - inflated_offset;
2672 if (inflated_offset > offset)
2673 inflated_addr += hpage_size;
2674
2675 if (inflated_addr > TASK_SIZE - len)
2676 return addr;
2677 return inflated_addr;
2678}
2679
2680#ifdef CONFIG_NUMA
2681static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2682{
2683 struct inode *inode = file_inode(vma->vm_file);
2684 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2685}
2686
2687static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2688 unsigned long addr, pgoff_t *ilx)
2689{
2690 struct inode *inode = file_inode(vma->vm_file);
2691 pgoff_t index;
2692
2693 /*
2694 * Bias interleave by inode number to distribute better across nodes;
2695 * but this interface is independent of which page order is used, so
2696 * supplies only that bias, letting caller apply the offset (adjusted
2697 * by page order, as in shmem_get_pgoff_policy() and get_vma_policy()).
2698 */
2699 *ilx = inode->i_ino;
2700 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2701 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2702}
2703
2704static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
2705 pgoff_t index, unsigned int order, pgoff_t *ilx)
2706{
2707 struct mempolicy *mpol;
2708
2709 /* Bias interleave by inode number to distribute better across nodes */
2710 *ilx = info->vfs_inode.i_ino + (index >> order);
2711
2712 mpol = mpol_shared_policy_lookup(&info->policy, index);
2713 return mpol ? mpol : get_task_policy(current);
2714}
2715#else
2716static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
2717 pgoff_t index, unsigned int order, pgoff_t *ilx)
2718{
2719 *ilx = 0;
2720 return NULL;
2721}
2722#endif /* CONFIG_NUMA */
2723
2724int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2725{
2726 struct inode *inode = file_inode(file);
2727 struct shmem_inode_info *info = SHMEM_I(inode);
2728 int retval = -ENOMEM;
2729
2730 /*
2731 * What serializes the accesses to info->flags?
2732 * ipc_lock_object() when called from shmctl_do_lock(),
2733 * no serialization needed when called from shm_destroy().
2734 */
2735 if (lock && !(info->flags & VM_LOCKED)) {
2736 if (!user_shm_lock(inode->i_size, ucounts))
2737 goto out_nomem;
2738 info->flags |= VM_LOCKED;
2739 mapping_set_unevictable(file->f_mapping);
2740 }
2741 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2742 user_shm_unlock(inode->i_size, ucounts);
2743 info->flags &= ~VM_LOCKED;
2744 mapping_clear_unevictable(file->f_mapping);
2745 }
2746 retval = 0;
2747
2748out_nomem:
2749 return retval;
2750}
2751
2752static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2753{
2754 struct inode *inode = file_inode(file);
2755 struct shmem_inode_info *info = SHMEM_I(inode);
2756 int ret;
2757
2758 ret = seal_check_write(info->seals, vma);
2759 if (ret)
2760 return ret;
2761
2762 file_accessed(file);
2763 /* This is anonymous shared memory if it is unlinked at the time of mmap */
2764 if (inode->i_nlink)
2765 vma->vm_ops = &shmem_vm_ops;
2766 else
2767 vma->vm_ops = &shmem_anon_vm_ops;
2768 return 0;
2769}
2770
2771static int shmem_file_open(struct inode *inode, struct file *file)
2772{
2773 file->f_mode |= FMODE_CAN_ODIRECT;
2774 return generic_file_open(inode, file);
2775}
2776
2777#ifdef CONFIG_TMPFS_XATTR
2778static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2779
2780#if IS_ENABLED(CONFIG_UNICODE)
2781/*
2782 * shmem_inode_casefold_flags - Deal with casefold file attribute flag
2783 *
2784 * The casefold file attribute needs some special checks. I can just be added to
2785 * an empty dir, and can't be removed from a non-empty dir.
2786 */
2787static int shmem_inode_casefold_flags(struct inode *inode, unsigned int fsflags,
2788 struct dentry *dentry, unsigned int *i_flags)
2789{
2790 unsigned int old = inode->i_flags;
2791 struct super_block *sb = inode->i_sb;
2792
2793 if (fsflags & FS_CASEFOLD_FL) {
2794 if (!(old & S_CASEFOLD)) {
2795 if (!sb->s_encoding)
2796 return -EOPNOTSUPP;
2797
2798 if (!S_ISDIR(inode->i_mode))
2799 return -ENOTDIR;
2800
2801 if (dentry && !simple_empty(dentry))
2802 return -ENOTEMPTY;
2803 }
2804
2805 *i_flags = *i_flags | S_CASEFOLD;
2806 } else if (old & S_CASEFOLD) {
2807 if (dentry && !simple_empty(dentry))
2808 return -ENOTEMPTY;
2809 }
2810
2811 return 0;
2812}
2813#else
2814static int shmem_inode_casefold_flags(struct inode *inode, unsigned int fsflags,
2815 struct dentry *dentry, unsigned int *i_flags)
2816{
2817 if (fsflags & FS_CASEFOLD_FL)
2818 return -EOPNOTSUPP;
2819
2820 return 0;
2821}
2822#endif
2823
2824/*
2825 * chattr's fsflags are unrelated to extended attributes,
2826 * but tmpfs has chosen to enable them under the same config option.
2827 */
2828static int shmem_set_inode_flags(struct inode *inode, unsigned int fsflags, struct dentry *dentry)
2829{
2830 unsigned int i_flags = 0;
2831 int ret;
2832
2833 ret = shmem_inode_casefold_flags(inode, fsflags, dentry, &i_flags);
2834 if (ret)
2835 return ret;
2836
2837 if (fsflags & FS_NOATIME_FL)
2838 i_flags |= S_NOATIME;
2839 if (fsflags & FS_APPEND_FL)
2840 i_flags |= S_APPEND;
2841 if (fsflags & FS_IMMUTABLE_FL)
2842 i_flags |= S_IMMUTABLE;
2843 /*
2844 * But FS_NODUMP_FL does not require any action in i_flags.
2845 */
2846 inode_set_flags(inode, i_flags, S_NOATIME | S_APPEND | S_IMMUTABLE | S_CASEFOLD);
2847
2848 return 0;
2849}
2850#else
2851static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags, struct dentry *dentry)
2852{
2853}
2854#define shmem_initxattrs NULL
2855#endif
2856
2857static struct offset_ctx *shmem_get_offset_ctx(struct inode *inode)
2858{
2859 return &SHMEM_I(inode)->dir_offsets;
2860}
2861
2862static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
2863 struct super_block *sb,
2864 struct inode *dir, umode_t mode,
2865 dev_t dev, unsigned long flags)
2866{
2867 struct inode *inode;
2868 struct shmem_inode_info *info;
2869 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2870 ino_t ino;
2871 int err;
2872
2873 err = shmem_reserve_inode(sb, &ino);
2874 if (err)
2875 return ERR_PTR(err);
2876
2877 inode = new_inode(sb);
2878 if (!inode) {
2879 shmem_free_inode(sb, 0);
2880 return ERR_PTR(-ENOSPC);
2881 }
2882
2883 inode->i_ino = ino;
2884 inode_init_owner(idmap, inode, dir, mode);
2885 inode->i_blocks = 0;
2886 simple_inode_init_ts(inode);
2887 inode->i_generation = get_random_u32();
2888 info = SHMEM_I(inode);
2889 memset(info, 0, (char *)inode - (char *)info);
2890 spin_lock_init(&info->lock);
2891 atomic_set(&info->stop_eviction, 0);
2892 info->seals = F_SEAL_SEAL;
2893 info->flags = flags & VM_NORESERVE;
2894 info->i_crtime = inode_get_mtime(inode);
2895 info->fsflags = (dir == NULL) ? 0 :
2896 SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
2897 if (info->fsflags)
2898 shmem_set_inode_flags(inode, info->fsflags, NULL);
2899 INIT_LIST_HEAD(&info->shrinklist);
2900 INIT_LIST_HEAD(&info->swaplist);
2901 simple_xattrs_init(&info->xattrs);
2902 cache_no_acl(inode);
2903 if (sbinfo->noswap)
2904 mapping_set_unevictable(inode->i_mapping);
2905
2906 /* Don't consider 'deny' for emergencies and 'force' for testing */
2907 if (sbinfo->huge)
2908 mapping_set_large_folios(inode->i_mapping);
2909
2910 switch (mode & S_IFMT) {
2911 default:
2912 inode->i_op = &shmem_special_inode_operations;
2913 init_special_inode(inode, mode, dev);
2914 break;
2915 case S_IFREG:
2916 inode->i_mapping->a_ops = &shmem_aops;
2917 inode->i_op = &shmem_inode_operations;
2918 inode->i_fop = &shmem_file_operations;
2919 mpol_shared_policy_init(&info->policy,
2920 shmem_get_sbmpol(sbinfo));
2921 break;
2922 case S_IFDIR:
2923 inc_nlink(inode);
2924 /* Some things misbehave if size == 0 on a directory */
2925 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2926 inode->i_op = &shmem_dir_inode_operations;
2927 inode->i_fop = &simple_offset_dir_operations;
2928 simple_offset_init(shmem_get_offset_ctx(inode));
2929 break;
2930 case S_IFLNK:
2931 /*
2932 * Must not load anything in the rbtree,
2933 * mpol_free_shared_policy will not be called.
2934 */
2935 mpol_shared_policy_init(&info->policy, NULL);
2936 break;
2937 }
2938
2939 lockdep_annotate_inode_mutex_key(inode);
2940 return inode;
2941}
2942
2943#ifdef CONFIG_TMPFS_QUOTA
2944static struct inode *shmem_get_inode(struct mnt_idmap *idmap,
2945 struct super_block *sb, struct inode *dir,
2946 umode_t mode, dev_t dev, unsigned long flags)
2947{
2948 int err;
2949 struct inode *inode;
2950
2951 inode = __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
2952 if (IS_ERR(inode))
2953 return inode;
2954
2955 err = dquot_initialize(inode);
2956 if (err)
2957 goto errout;
2958
2959 err = dquot_alloc_inode(inode);
2960 if (err) {
2961 dquot_drop(inode);
2962 goto errout;
2963 }
2964 return inode;
2965
2966errout:
2967 inode->i_flags |= S_NOQUOTA;
2968 iput(inode);
2969 return ERR_PTR(err);
2970}
2971#else
2972static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
2973 struct super_block *sb, struct inode *dir,
2974 umode_t mode, dev_t dev, unsigned long flags)
2975{
2976 return __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
2977}
2978#endif /* CONFIG_TMPFS_QUOTA */
2979
2980#ifdef CONFIG_USERFAULTFD
2981int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
2982 struct vm_area_struct *dst_vma,
2983 unsigned long dst_addr,
2984 unsigned long src_addr,
2985 uffd_flags_t flags,
2986 struct folio **foliop)
2987{
2988 struct inode *inode = file_inode(dst_vma->vm_file);
2989 struct shmem_inode_info *info = SHMEM_I(inode);
2990 struct address_space *mapping = inode->i_mapping;
2991 gfp_t gfp = mapping_gfp_mask(mapping);
2992 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2993 void *page_kaddr;
2994 struct folio *folio;
2995 int ret;
2996 pgoff_t max_off;
2997
2998 if (shmem_inode_acct_blocks(inode, 1)) {
2999 /*
3000 * We may have got a page, returned -ENOENT triggering a retry,
3001 * and now we find ourselves with -ENOMEM. Release the page, to
3002 * avoid a BUG_ON in our caller.
3003 */
3004 if (unlikely(*foliop)) {
3005 folio_put(*foliop);
3006 *foliop = NULL;
3007 }
3008 return -ENOMEM;
3009 }
3010
3011 if (!*foliop) {
3012 ret = -ENOMEM;
3013 folio = shmem_alloc_folio(gfp, 0, info, pgoff);
3014 if (!folio)
3015 goto out_unacct_blocks;
3016
3017 if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) {
3018 page_kaddr = kmap_local_folio(folio, 0);
3019 /*
3020 * The read mmap_lock is held here. Despite the
3021 * mmap_lock being read recursive a deadlock is still
3022 * possible if a writer has taken a lock. For example:
3023 *
3024 * process A thread 1 takes read lock on own mmap_lock
3025 * process A thread 2 calls mmap, blocks taking write lock
3026 * process B thread 1 takes page fault, read lock on own mmap lock
3027 * process B thread 2 calls mmap, blocks taking write lock
3028 * process A thread 1 blocks taking read lock on process B
3029 * process B thread 1 blocks taking read lock on process A
3030 *
3031 * Disable page faults to prevent potential deadlock
3032 * and retry the copy outside the mmap_lock.
3033 */
3034 pagefault_disable();
3035 ret = copy_from_user(page_kaddr,
3036 (const void __user *)src_addr,
3037 PAGE_SIZE);
3038 pagefault_enable();
3039 kunmap_local(page_kaddr);
3040
3041 /* fallback to copy_from_user outside mmap_lock */
3042 if (unlikely(ret)) {
3043 *foliop = folio;
3044 ret = -ENOENT;
3045 /* don't free the page */
3046 goto out_unacct_blocks;
3047 }
3048
3049 flush_dcache_folio(folio);
3050 } else { /* ZEROPAGE */
3051 clear_user_highpage(&folio->page, dst_addr);
3052 }
3053 } else {
3054 folio = *foliop;
3055 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
3056 *foliop = NULL;
3057 }
3058
3059 VM_BUG_ON(folio_test_locked(folio));
3060 VM_BUG_ON(folio_test_swapbacked(folio));
3061 __folio_set_locked(folio);
3062 __folio_set_swapbacked(folio);
3063 __folio_mark_uptodate(folio);
3064
3065 ret = -EFAULT;
3066 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
3067 if (unlikely(pgoff >= max_off))
3068 goto out_release;
3069
3070 ret = mem_cgroup_charge(folio, dst_vma->vm_mm, gfp);
3071 if (ret)
3072 goto out_release;
3073 ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL, gfp);
3074 if (ret)
3075 goto out_release;
3076
3077 ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
3078 &folio->page, true, flags);
3079 if (ret)
3080 goto out_delete_from_cache;
3081
3082 shmem_recalc_inode(inode, 1, 0);
3083 folio_unlock(folio);
3084 return 0;
3085out_delete_from_cache:
3086 filemap_remove_folio(folio);
3087out_release:
3088 folio_unlock(folio);
3089 folio_put(folio);
3090out_unacct_blocks:
3091 shmem_inode_unacct_blocks(inode, 1);
3092 return ret;
3093}
3094#endif /* CONFIG_USERFAULTFD */
3095
3096#ifdef CONFIG_TMPFS
3097static const struct inode_operations shmem_symlink_inode_operations;
3098static const struct inode_operations shmem_short_symlink_operations;
3099
3100static int
3101shmem_write_begin(struct file *file, struct address_space *mapping,
3102 loff_t pos, unsigned len,
3103 struct folio **foliop, void **fsdata)
3104{
3105 struct inode *inode = mapping->host;
3106 struct shmem_inode_info *info = SHMEM_I(inode);
3107 pgoff_t index = pos >> PAGE_SHIFT;
3108 struct folio *folio;
3109 int ret = 0;
3110
3111 /* i_rwsem is held by caller */
3112 if (unlikely(info->seals & (F_SEAL_GROW |
3113 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
3114 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
3115 return -EPERM;
3116 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
3117 return -EPERM;
3118 }
3119
3120 ret = shmem_get_folio(inode, index, pos + len, &folio, SGP_WRITE);
3121 if (ret)
3122 return ret;
3123
3124 if (folio_test_hwpoison(folio) ||
3125 (folio_test_large(folio) && folio_test_has_hwpoisoned(folio))) {
3126 folio_unlock(folio);
3127 folio_put(folio);
3128 return -EIO;
3129 }
3130
3131 *foliop = folio;
3132 return 0;
3133}
3134
3135static int
3136shmem_write_end(struct file *file, struct address_space *mapping,
3137 loff_t pos, unsigned len, unsigned copied,
3138 struct folio *folio, void *fsdata)
3139{
3140 struct inode *inode = mapping->host;
3141
3142 if (pos + copied > inode->i_size)
3143 i_size_write(inode, pos + copied);
3144
3145 if (!folio_test_uptodate(folio)) {
3146 if (copied < folio_size(folio)) {
3147 size_t from = offset_in_folio(folio, pos);
3148 folio_zero_segments(folio, 0, from,
3149 from + copied, folio_size(folio));
3150 }
3151 folio_mark_uptodate(folio);
3152 }
3153 folio_mark_dirty(folio);
3154 folio_unlock(folio);
3155 folio_put(folio);
3156
3157 return copied;
3158}
3159
3160static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
3161{
3162 struct file *file = iocb->ki_filp;
3163 struct inode *inode = file_inode(file);
3164 struct address_space *mapping = inode->i_mapping;
3165 pgoff_t index;
3166 unsigned long offset;
3167 int error = 0;
3168 ssize_t retval = 0;
3169
3170 for (;;) {
3171 struct folio *folio = NULL;
3172 struct page *page = NULL;
3173 unsigned long nr, ret;
3174 loff_t end_offset, i_size = i_size_read(inode);
3175 bool fallback_page_copy = false;
3176 size_t fsize;
3177
3178 if (unlikely(iocb->ki_pos >= i_size))
3179 break;
3180
3181 index = iocb->ki_pos >> PAGE_SHIFT;
3182 error = shmem_get_folio(inode, index, 0, &folio, SGP_READ);
3183 if (error) {
3184 if (error == -EINVAL)
3185 error = 0;
3186 break;
3187 }
3188 if (folio) {
3189 folio_unlock(folio);
3190
3191 page = folio_file_page(folio, index);
3192 if (PageHWPoison(page)) {
3193 folio_put(folio);
3194 error = -EIO;
3195 break;
3196 }
3197
3198 if (folio_test_large(folio) &&
3199 folio_test_has_hwpoisoned(folio))
3200 fallback_page_copy = true;
3201 }
3202
3203 /*
3204 * We must evaluate after, since reads (unlike writes)
3205 * are called without i_rwsem protection against truncate
3206 */
3207 i_size = i_size_read(inode);
3208 if (unlikely(iocb->ki_pos >= i_size)) {
3209 if (folio)
3210 folio_put(folio);
3211 break;
3212 }
3213 end_offset = min_t(loff_t, i_size, iocb->ki_pos + to->count);
3214 if (folio && likely(!fallback_page_copy))
3215 fsize = folio_size(folio);
3216 else
3217 fsize = PAGE_SIZE;
3218 offset = iocb->ki_pos & (fsize - 1);
3219 nr = min_t(loff_t, end_offset - iocb->ki_pos, fsize - offset);
3220
3221 if (folio) {
3222 /*
3223 * If users can be writing to this page using arbitrary
3224 * virtual addresses, take care about potential aliasing
3225 * before reading the page on the kernel side.
3226 */
3227 if (mapping_writably_mapped(mapping)) {
3228 if (likely(!fallback_page_copy))
3229 flush_dcache_folio(folio);
3230 else
3231 flush_dcache_page(page);
3232 }
3233
3234 /*
3235 * Mark the folio accessed if we read the beginning.
3236 */
3237 if (!offset)
3238 folio_mark_accessed(folio);
3239 /*
3240 * Ok, we have the page, and it's up-to-date, so
3241 * now we can copy it to user space...
3242 */
3243 if (likely(!fallback_page_copy))
3244 ret = copy_folio_to_iter(folio, offset, nr, to);
3245 else
3246 ret = copy_page_to_iter(page, offset, nr, to);
3247 folio_put(folio);
3248 } else if (user_backed_iter(to)) {
3249 /*
3250 * Copy to user tends to be so well optimized, but
3251 * clear_user() not so much, that it is noticeably
3252 * faster to copy the zero page instead of clearing.
3253 */
3254 ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to);
3255 } else {
3256 /*
3257 * But submitting the same page twice in a row to
3258 * splice() - or others? - can result in confusion:
3259 * so don't attempt that optimization on pipes etc.
3260 */
3261 ret = iov_iter_zero(nr, to);
3262 }
3263
3264 retval += ret;
3265 iocb->ki_pos += ret;
3266
3267 if (!iov_iter_count(to))
3268 break;
3269 if (ret < nr) {
3270 error = -EFAULT;
3271 break;
3272 }
3273 cond_resched();
3274 }
3275
3276 file_accessed(file);
3277 return retval ? retval : error;
3278}
3279
3280static ssize_t shmem_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
3281{
3282 struct file *file = iocb->ki_filp;
3283 struct inode *inode = file->f_mapping->host;
3284 ssize_t ret;
3285
3286 inode_lock(inode);
3287 ret = generic_write_checks(iocb, from);
3288 if (ret <= 0)
3289 goto unlock;
3290 ret = file_remove_privs(file);
3291 if (ret)
3292 goto unlock;
3293 ret = file_update_time(file);
3294 if (ret)
3295 goto unlock;
3296 ret = generic_perform_write(iocb, from);
3297unlock:
3298 inode_unlock(inode);
3299 return ret;
3300}
3301
3302static bool zero_pipe_buf_get(struct pipe_inode_info *pipe,
3303 struct pipe_buffer *buf)
3304{
3305 return true;
3306}
3307
3308static void zero_pipe_buf_release(struct pipe_inode_info *pipe,
3309 struct pipe_buffer *buf)
3310{
3311}
3312
3313static bool zero_pipe_buf_try_steal(struct pipe_inode_info *pipe,
3314 struct pipe_buffer *buf)
3315{
3316 return false;
3317}
3318
3319static const struct pipe_buf_operations zero_pipe_buf_ops = {
3320 .release = zero_pipe_buf_release,
3321 .try_steal = zero_pipe_buf_try_steal,
3322 .get = zero_pipe_buf_get,
3323};
3324
3325static size_t splice_zeropage_into_pipe(struct pipe_inode_info *pipe,
3326 loff_t fpos, size_t size)
3327{
3328 size_t offset = fpos & ~PAGE_MASK;
3329
3330 size = min_t(size_t, size, PAGE_SIZE - offset);
3331
3332 if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
3333 struct pipe_buffer *buf = pipe_head_buf(pipe);
3334
3335 *buf = (struct pipe_buffer) {
3336 .ops = &zero_pipe_buf_ops,
3337 .page = ZERO_PAGE(0),
3338 .offset = offset,
3339 .len = size,
3340 };
3341 pipe->head++;
3342 }
3343
3344 return size;
3345}
3346
3347static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
3348 struct pipe_inode_info *pipe,
3349 size_t len, unsigned int flags)
3350{
3351 struct inode *inode = file_inode(in);
3352 struct address_space *mapping = inode->i_mapping;
3353 struct folio *folio = NULL;
3354 size_t total_spliced = 0, used, npages, n, part;
3355 loff_t isize;
3356 int error = 0;
3357
3358 /* Work out how much data we can actually add into the pipe */
3359 used = pipe_occupancy(pipe->head, pipe->tail);
3360 npages = max_t(ssize_t, pipe->max_usage - used, 0);
3361 len = min_t(size_t, len, npages * PAGE_SIZE);
3362
3363 do {
3364 bool fallback_page_splice = false;
3365 struct page *page = NULL;
3366 pgoff_t index;
3367 size_t size;
3368
3369 if (*ppos >= i_size_read(inode))
3370 break;
3371
3372 index = *ppos >> PAGE_SHIFT;
3373 error = shmem_get_folio(inode, index, 0, &folio, SGP_READ);
3374 if (error) {
3375 if (error == -EINVAL)
3376 error = 0;
3377 break;
3378 }
3379 if (folio) {
3380 folio_unlock(folio);
3381
3382 page = folio_file_page(folio, index);
3383 if (PageHWPoison(page)) {
3384 error = -EIO;
3385 break;
3386 }
3387
3388 if (folio_test_large(folio) &&
3389 folio_test_has_hwpoisoned(folio))
3390 fallback_page_splice = true;
3391 }
3392
3393 /*
3394 * i_size must be checked after we know the pages are Uptodate.
3395 *
3396 * Checking i_size after the check allows us to calculate
3397 * the correct value for "nr", which means the zero-filled
3398 * part of the page is not copied back to userspace (unless
3399 * another truncate extends the file - this is desired though).
3400 */
3401 isize = i_size_read(inode);
3402 if (unlikely(*ppos >= isize))
3403 break;
3404 /*
3405 * Fallback to PAGE_SIZE splice if the large folio has hwpoisoned
3406 * pages.
3407 */
3408 size = len;
3409 if (unlikely(fallback_page_splice)) {
3410 size_t offset = *ppos & ~PAGE_MASK;
3411
3412 size = umin(size, PAGE_SIZE - offset);
3413 }
3414 part = min_t(loff_t, isize - *ppos, size);
3415
3416 if (folio) {
3417 /*
3418 * If users can be writing to this page using arbitrary
3419 * virtual addresses, take care about potential aliasing
3420 * before reading the page on the kernel side.
3421 */
3422 if (mapping_writably_mapped(mapping)) {
3423 if (likely(!fallback_page_splice))
3424 flush_dcache_folio(folio);
3425 else
3426 flush_dcache_page(page);
3427 }
3428 folio_mark_accessed(folio);
3429 /*
3430 * Ok, we have the page, and it's up-to-date, so we can
3431 * now splice it into the pipe.
3432 */
3433 n = splice_folio_into_pipe(pipe, folio, *ppos, part);
3434 folio_put(folio);
3435 folio = NULL;
3436 } else {
3437 n = splice_zeropage_into_pipe(pipe, *ppos, part);
3438 }
3439
3440 if (!n)
3441 break;
3442 len -= n;
3443 total_spliced += n;
3444 *ppos += n;
3445 in->f_ra.prev_pos = *ppos;
3446 if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
3447 break;
3448
3449 cond_resched();
3450 } while (len);
3451
3452 if (folio)
3453 folio_put(folio);
3454
3455 file_accessed(in);
3456 return total_spliced ? total_spliced : error;
3457}
3458
3459static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
3460{
3461 struct address_space *mapping = file->f_mapping;
3462 struct inode *inode = mapping->host;
3463
3464 if (whence != SEEK_DATA && whence != SEEK_HOLE)
3465 return generic_file_llseek_size(file, offset, whence,
3466 MAX_LFS_FILESIZE, i_size_read(inode));
3467 if (offset < 0)
3468 return -ENXIO;
3469
3470 inode_lock(inode);
3471 /* We're holding i_rwsem so we can access i_size directly */
3472 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
3473 if (offset >= 0)
3474 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
3475 inode_unlock(inode);
3476 return offset;
3477}
3478
3479static long shmem_fallocate(struct file *file, int mode, loff_t offset,
3480 loff_t len)
3481{
3482 struct inode *inode = file_inode(file);
3483 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3484 struct shmem_inode_info *info = SHMEM_I(inode);
3485 struct shmem_falloc shmem_falloc;
3486 pgoff_t start, index, end, undo_fallocend;
3487 int error;
3488
3489 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
3490 return -EOPNOTSUPP;
3491
3492 inode_lock(inode);
3493
3494 if (mode & FALLOC_FL_PUNCH_HOLE) {
3495 struct address_space *mapping = file->f_mapping;
3496 loff_t unmap_start = round_up(offset, PAGE_SIZE);
3497 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
3498 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
3499
3500 /* protected by i_rwsem */
3501 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
3502 error = -EPERM;
3503 goto out;
3504 }
3505
3506 shmem_falloc.waitq = &shmem_falloc_waitq;
3507 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
3508 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
3509 spin_lock(&inode->i_lock);
3510 inode->i_private = &shmem_falloc;
3511 spin_unlock(&inode->i_lock);
3512
3513 if ((u64)unmap_end > (u64)unmap_start)
3514 unmap_mapping_range(mapping, unmap_start,
3515 1 + unmap_end - unmap_start, 0);
3516 shmem_truncate_range(inode, offset, offset + len - 1);
3517 /* No need to unmap again: hole-punching leaves COWed pages */
3518
3519 spin_lock(&inode->i_lock);
3520 inode->i_private = NULL;
3521 wake_up_all(&shmem_falloc_waitq);
3522 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
3523 spin_unlock(&inode->i_lock);
3524 error = 0;
3525 goto out;
3526 }
3527
3528 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
3529 error = inode_newsize_ok(inode, offset + len);
3530 if (error)
3531 goto out;
3532
3533 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
3534 error = -EPERM;
3535 goto out;
3536 }
3537
3538 start = offset >> PAGE_SHIFT;
3539 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
3540 /* Try to avoid a swapstorm if len is impossible to satisfy */
3541 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
3542 error = -ENOSPC;
3543 goto out;
3544 }
3545
3546 shmem_falloc.waitq = NULL;
3547 shmem_falloc.start = start;
3548 shmem_falloc.next = start;
3549 shmem_falloc.nr_falloced = 0;
3550 shmem_falloc.nr_unswapped = 0;
3551 spin_lock(&inode->i_lock);
3552 inode->i_private = &shmem_falloc;
3553 spin_unlock(&inode->i_lock);
3554
3555 /*
3556 * info->fallocend is only relevant when huge pages might be
3557 * involved: to prevent split_huge_page() freeing fallocated
3558 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
3559 */
3560 undo_fallocend = info->fallocend;
3561 if (info->fallocend < end)
3562 info->fallocend = end;
3563
3564 for (index = start; index < end; ) {
3565 struct folio *folio;
3566
3567 /*
3568 * Check for fatal signal so that we abort early in OOM
3569 * situations. We don't want to abort in case of non-fatal
3570 * signals as large fallocate can take noticeable time and
3571 * e.g. periodic timers may result in fallocate constantly
3572 * restarting.
3573 */
3574 if (fatal_signal_pending(current))
3575 error = -EINTR;
3576 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
3577 error = -ENOMEM;
3578 else
3579 error = shmem_get_folio(inode, index, offset + len,
3580 &folio, SGP_FALLOC);
3581 if (error) {
3582 info->fallocend = undo_fallocend;
3583 /* Remove the !uptodate folios we added */
3584 if (index > start) {
3585 shmem_undo_range(inode,
3586 (loff_t)start << PAGE_SHIFT,
3587 ((loff_t)index << PAGE_SHIFT) - 1, true);
3588 }
3589 goto undone;
3590 }
3591
3592 /*
3593 * Here is a more important optimization than it appears:
3594 * a second SGP_FALLOC on the same large folio will clear it,
3595 * making it uptodate and un-undoable if we fail later.
3596 */
3597 index = folio_next_index(folio);
3598 /* Beware 32-bit wraparound */
3599 if (!index)
3600 index--;
3601
3602 /*
3603 * Inform shmem_writepage() how far we have reached.
3604 * No need for lock or barrier: we have the page lock.
3605 */
3606 if (!folio_test_uptodate(folio))
3607 shmem_falloc.nr_falloced += index - shmem_falloc.next;
3608 shmem_falloc.next = index;
3609
3610 /*
3611 * If !uptodate, leave it that way so that freeable folios
3612 * can be recognized if we need to rollback on error later.
3613 * But mark it dirty so that memory pressure will swap rather
3614 * than free the folios we are allocating (and SGP_CACHE folios
3615 * might still be clean: we now need to mark those dirty too).
3616 */
3617 folio_mark_dirty(folio);
3618 folio_unlock(folio);
3619 folio_put(folio);
3620 cond_resched();
3621 }
3622
3623 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
3624 i_size_write(inode, offset + len);
3625undone:
3626 spin_lock(&inode->i_lock);
3627 inode->i_private = NULL;
3628 spin_unlock(&inode->i_lock);
3629out:
3630 if (!error)
3631 file_modified(file);
3632 inode_unlock(inode);
3633 return error;
3634}
3635
3636static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
3637{
3638 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
3639
3640 buf->f_type = TMPFS_MAGIC;
3641 buf->f_bsize = PAGE_SIZE;
3642 buf->f_namelen = NAME_MAX;
3643 if (sbinfo->max_blocks) {
3644 buf->f_blocks = sbinfo->max_blocks;
3645 buf->f_bavail =
3646 buf->f_bfree = sbinfo->max_blocks -
3647 percpu_counter_sum(&sbinfo->used_blocks);
3648 }
3649 if (sbinfo->max_inodes) {
3650 buf->f_files = sbinfo->max_inodes;
3651 buf->f_ffree = sbinfo->free_ispace / BOGO_INODE_SIZE;
3652 }
3653 /* else leave those fields 0 like simple_statfs */
3654
3655 buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
3656
3657 return 0;
3658}
3659
3660/*
3661 * File creation. Allocate an inode, and we're done..
3662 */
3663static int
3664shmem_mknod(struct mnt_idmap *idmap, struct inode *dir,
3665 struct dentry *dentry, umode_t mode, dev_t dev)
3666{
3667 struct inode *inode;
3668 int error;
3669
3670 if (!generic_ci_validate_strict_name(dir, &dentry->d_name))
3671 return -EINVAL;
3672
3673 inode = shmem_get_inode(idmap, dir->i_sb, dir, mode, dev, VM_NORESERVE);
3674 if (IS_ERR(inode))
3675 return PTR_ERR(inode);
3676
3677 error = simple_acl_create(dir, inode);
3678 if (error)
3679 goto out_iput;
3680 error = security_inode_init_security(inode, dir, &dentry->d_name,
3681 shmem_initxattrs, NULL);
3682 if (error && error != -EOPNOTSUPP)
3683 goto out_iput;
3684
3685 error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3686 if (error)
3687 goto out_iput;
3688
3689 dir->i_size += BOGO_DIRENT_SIZE;
3690 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
3691 inode_inc_iversion(dir);
3692
3693 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3694 d_add(dentry, inode);
3695 else
3696 d_instantiate(dentry, inode);
3697
3698 dget(dentry); /* Extra count - pin the dentry in core */
3699 return error;
3700
3701out_iput:
3702 iput(inode);
3703 return error;
3704}
3705
3706static int
3707shmem_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
3708 struct file *file, umode_t mode)
3709{
3710 struct inode *inode;
3711 int error;
3712
3713 inode = shmem_get_inode(idmap, dir->i_sb, dir, mode, 0, VM_NORESERVE);
3714 if (IS_ERR(inode)) {
3715 error = PTR_ERR(inode);
3716 goto err_out;
3717 }
3718 error = security_inode_init_security(inode, dir, NULL,
3719 shmem_initxattrs, NULL);
3720 if (error && error != -EOPNOTSUPP)
3721 goto out_iput;
3722 error = simple_acl_create(dir, inode);
3723 if (error)
3724 goto out_iput;
3725 d_tmpfile(file, inode);
3726
3727err_out:
3728 return finish_open_simple(file, error);
3729out_iput:
3730 iput(inode);
3731 return error;
3732}
3733
3734static int shmem_mkdir(struct mnt_idmap *idmap, struct inode *dir,
3735 struct dentry *dentry, umode_t mode)
3736{
3737 int error;
3738
3739 error = shmem_mknod(idmap, dir, dentry, mode | S_IFDIR, 0);
3740 if (error)
3741 return error;
3742 inc_nlink(dir);
3743 return 0;
3744}
3745
3746static int shmem_create(struct mnt_idmap *idmap, struct inode *dir,
3747 struct dentry *dentry, umode_t mode, bool excl)
3748{
3749 return shmem_mknod(idmap, dir, dentry, mode | S_IFREG, 0);
3750}
3751
3752/*
3753 * Link a file..
3754 */
3755static int shmem_link(struct dentry *old_dentry, struct inode *dir,
3756 struct dentry *dentry)
3757{
3758 struct inode *inode = d_inode(old_dentry);
3759 int ret = 0;
3760
3761 /*
3762 * No ordinary (disk based) filesystem counts links as inodes;
3763 * but each new link needs a new dentry, pinning lowmem, and
3764 * tmpfs dentries cannot be pruned until they are unlinked.
3765 * But if an O_TMPFILE file is linked into the tmpfs, the
3766 * first link must skip that, to get the accounting right.
3767 */
3768 if (inode->i_nlink) {
3769 ret = shmem_reserve_inode(inode->i_sb, NULL);
3770 if (ret)
3771 goto out;
3772 }
3773
3774 ret = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3775 if (ret) {
3776 if (inode->i_nlink)
3777 shmem_free_inode(inode->i_sb, 0);
3778 goto out;
3779 }
3780
3781 dir->i_size += BOGO_DIRENT_SIZE;
3782 inode_set_mtime_to_ts(dir,
3783 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
3784 inode_inc_iversion(dir);
3785 inc_nlink(inode);
3786 ihold(inode); /* New dentry reference */
3787 dget(dentry); /* Extra pinning count for the created dentry */
3788 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3789 d_add(dentry, inode);
3790 else
3791 d_instantiate(dentry, inode);
3792out:
3793 return ret;
3794}
3795
3796static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3797{
3798 struct inode *inode = d_inode(dentry);
3799
3800 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3801 shmem_free_inode(inode->i_sb, 0);
3802
3803 simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
3804
3805 dir->i_size -= BOGO_DIRENT_SIZE;
3806 inode_set_mtime_to_ts(dir,
3807 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
3808 inode_inc_iversion(dir);
3809 drop_nlink(inode);
3810 dput(dentry); /* Undo the count from "create" - does all the work */
3811
3812 /*
3813 * For now, VFS can't deal with case-insensitive negative dentries, so
3814 * we invalidate them
3815 */
3816 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3817 d_invalidate(dentry);
3818
3819 return 0;
3820}
3821
3822static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3823{
3824 if (!simple_empty(dentry))
3825 return -ENOTEMPTY;
3826
3827 drop_nlink(d_inode(dentry));
3828 drop_nlink(dir);
3829 return shmem_unlink(dir, dentry);
3830}
3831
3832static int shmem_whiteout(struct mnt_idmap *idmap,
3833 struct inode *old_dir, struct dentry *old_dentry)
3834{
3835 struct dentry *whiteout;
3836 int error;
3837
3838 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3839 if (!whiteout)
3840 return -ENOMEM;
3841
3842 error = shmem_mknod(idmap, old_dir, whiteout,
3843 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3844 dput(whiteout);
3845 if (error)
3846 return error;
3847
3848 /*
3849 * Cheat and hash the whiteout while the old dentry is still in
3850 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3851 *
3852 * d_lookup() will consistently find one of them at this point,
3853 * not sure which one, but that isn't even important.
3854 */
3855 d_rehash(whiteout);
3856 return 0;
3857}
3858
3859/*
3860 * The VFS layer already does all the dentry stuff for rename,
3861 * we just have to decrement the usage count for the target if
3862 * it exists so that the VFS layer correctly free's it when it
3863 * gets overwritten.
3864 */
3865static int shmem_rename2(struct mnt_idmap *idmap,
3866 struct inode *old_dir, struct dentry *old_dentry,
3867 struct inode *new_dir, struct dentry *new_dentry,
3868 unsigned int flags)
3869{
3870 struct inode *inode = d_inode(old_dentry);
3871 int they_are_dirs = S_ISDIR(inode->i_mode);
3872 int error;
3873
3874 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3875 return -EINVAL;
3876
3877 if (flags & RENAME_EXCHANGE)
3878 return simple_offset_rename_exchange(old_dir, old_dentry,
3879 new_dir, new_dentry);
3880
3881 if (!simple_empty(new_dentry))
3882 return -ENOTEMPTY;
3883
3884 if (flags & RENAME_WHITEOUT) {
3885 error = shmem_whiteout(idmap, old_dir, old_dentry);
3886 if (error)
3887 return error;
3888 }
3889
3890 error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
3891 if (error)
3892 return error;
3893
3894 if (d_really_is_positive(new_dentry)) {
3895 (void) shmem_unlink(new_dir, new_dentry);
3896 if (they_are_dirs) {
3897 drop_nlink(d_inode(new_dentry));
3898 drop_nlink(old_dir);
3899 }
3900 } else if (they_are_dirs) {
3901 drop_nlink(old_dir);
3902 inc_nlink(new_dir);
3903 }
3904
3905 old_dir->i_size -= BOGO_DIRENT_SIZE;
3906 new_dir->i_size += BOGO_DIRENT_SIZE;
3907 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
3908 inode_inc_iversion(old_dir);
3909 inode_inc_iversion(new_dir);
3910 return 0;
3911}
3912
3913static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
3914 struct dentry *dentry, const char *symname)
3915{
3916 int error;
3917 int len;
3918 struct inode *inode;
3919 struct folio *folio;
3920
3921 len = strlen(symname) + 1;
3922 if (len > PAGE_SIZE)
3923 return -ENAMETOOLONG;
3924
3925 inode = shmem_get_inode(idmap, dir->i_sb, dir, S_IFLNK | 0777, 0,
3926 VM_NORESERVE);
3927 if (IS_ERR(inode))
3928 return PTR_ERR(inode);
3929
3930 error = security_inode_init_security(inode, dir, &dentry->d_name,
3931 shmem_initxattrs, NULL);
3932 if (error && error != -EOPNOTSUPP)
3933 goto out_iput;
3934
3935 error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3936 if (error)
3937 goto out_iput;
3938
3939 inode->i_size = len-1;
3940 if (len <= SHORT_SYMLINK_LEN) {
3941 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3942 if (!inode->i_link) {
3943 error = -ENOMEM;
3944 goto out_remove_offset;
3945 }
3946 inode->i_op = &shmem_short_symlink_operations;
3947 } else {
3948 inode_nohighmem(inode);
3949 inode->i_mapping->a_ops = &shmem_aops;
3950 error = shmem_get_folio(inode, 0, 0, &folio, SGP_WRITE);
3951 if (error)
3952 goto out_remove_offset;
3953 inode->i_op = &shmem_symlink_inode_operations;
3954 memcpy(folio_address(folio), symname, len);
3955 folio_mark_uptodate(folio);
3956 folio_mark_dirty(folio);
3957 folio_unlock(folio);
3958 folio_put(folio);
3959 }
3960 dir->i_size += BOGO_DIRENT_SIZE;
3961 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
3962 inode_inc_iversion(dir);
3963 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3964 d_add(dentry, inode);
3965 else
3966 d_instantiate(dentry, inode);
3967 dget(dentry);
3968 return 0;
3969
3970out_remove_offset:
3971 simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
3972out_iput:
3973 iput(inode);
3974 return error;
3975}
3976
3977static void shmem_put_link(void *arg)
3978{
3979 folio_mark_accessed(arg);
3980 folio_put(arg);
3981}
3982
3983static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
3984 struct delayed_call *done)
3985{
3986 struct folio *folio = NULL;
3987 int error;
3988
3989 if (!dentry) {
3990 folio = filemap_get_folio(inode->i_mapping, 0);
3991 if (IS_ERR(folio))
3992 return ERR_PTR(-ECHILD);
3993 if (PageHWPoison(folio_page(folio, 0)) ||
3994 !folio_test_uptodate(folio)) {
3995 folio_put(folio);
3996 return ERR_PTR(-ECHILD);
3997 }
3998 } else {
3999 error = shmem_get_folio(inode, 0, 0, &folio, SGP_READ);
4000 if (error)
4001 return ERR_PTR(error);
4002 if (!folio)
4003 return ERR_PTR(-ECHILD);
4004 if (PageHWPoison(folio_page(folio, 0))) {
4005 folio_unlock(folio);
4006 folio_put(folio);
4007 return ERR_PTR(-ECHILD);
4008 }
4009 folio_unlock(folio);
4010 }
4011 set_delayed_call(done, shmem_put_link, folio);
4012 return folio_address(folio);
4013}
4014
4015#ifdef CONFIG_TMPFS_XATTR
4016
4017static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
4018{
4019 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
4020
4021 fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
4022
4023 return 0;
4024}
4025
4026static int shmem_fileattr_set(struct mnt_idmap *idmap,
4027 struct dentry *dentry, struct fileattr *fa)
4028{
4029 struct inode *inode = d_inode(dentry);
4030 struct shmem_inode_info *info = SHMEM_I(inode);
4031 int ret, flags;
4032
4033 if (fileattr_has_fsx(fa))
4034 return -EOPNOTSUPP;
4035 if (fa->flags & ~SHMEM_FL_USER_MODIFIABLE)
4036 return -EOPNOTSUPP;
4037
4038 flags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
4039 (fa->flags & SHMEM_FL_USER_MODIFIABLE);
4040
4041 ret = shmem_set_inode_flags(inode, flags, dentry);
4042
4043 if (ret)
4044 return ret;
4045
4046 info->fsflags = flags;
4047
4048 inode_set_ctime_current(inode);
4049 inode_inc_iversion(inode);
4050 return 0;
4051}
4052
4053/*
4054 * Superblocks without xattr inode operations may get some security.* xattr
4055 * support from the LSM "for free". As soon as we have any other xattrs
4056 * like ACLs, we also need to implement the security.* handlers at
4057 * filesystem level, though.
4058 */
4059
4060/*
4061 * Callback for security_inode_init_security() for acquiring xattrs.
4062 */
4063static int shmem_initxattrs(struct inode *inode,
4064 const struct xattr *xattr_array, void *fs_info)
4065{
4066 struct shmem_inode_info *info = SHMEM_I(inode);
4067 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
4068 const struct xattr *xattr;
4069 struct simple_xattr *new_xattr;
4070 size_t ispace = 0;
4071 size_t len;
4072
4073 if (sbinfo->max_inodes) {
4074 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
4075 ispace += simple_xattr_space(xattr->name,
4076 xattr->value_len + XATTR_SECURITY_PREFIX_LEN);
4077 }
4078 if (ispace) {
4079 raw_spin_lock(&sbinfo->stat_lock);
4080 if (sbinfo->free_ispace < ispace)
4081 ispace = 0;
4082 else
4083 sbinfo->free_ispace -= ispace;
4084 raw_spin_unlock(&sbinfo->stat_lock);
4085 if (!ispace)
4086 return -ENOSPC;
4087 }
4088 }
4089
4090 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
4091 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
4092 if (!new_xattr)
4093 break;
4094
4095 len = strlen(xattr->name) + 1;
4096 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
4097 GFP_KERNEL_ACCOUNT);
4098 if (!new_xattr->name) {
4099 kvfree(new_xattr);
4100 break;
4101 }
4102
4103 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
4104 XATTR_SECURITY_PREFIX_LEN);
4105 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
4106 xattr->name, len);
4107
4108 simple_xattr_add(&info->xattrs, new_xattr);
4109 }
4110
4111 if (xattr->name != NULL) {
4112 if (ispace) {
4113 raw_spin_lock(&sbinfo->stat_lock);
4114 sbinfo->free_ispace += ispace;
4115 raw_spin_unlock(&sbinfo->stat_lock);
4116 }
4117 simple_xattrs_free(&info->xattrs, NULL);
4118 return -ENOMEM;
4119 }
4120
4121 return 0;
4122}
4123
4124static int shmem_xattr_handler_get(const struct xattr_handler *handler,
4125 struct dentry *unused, struct inode *inode,
4126 const char *name, void *buffer, size_t size)
4127{
4128 struct shmem_inode_info *info = SHMEM_I(inode);
4129
4130 name = xattr_full_name(handler, name);
4131 return simple_xattr_get(&info->xattrs, name, buffer, size);
4132}
4133
4134static int shmem_xattr_handler_set(const struct xattr_handler *handler,
4135 struct mnt_idmap *idmap,
4136 struct dentry *unused, struct inode *inode,
4137 const char *name, const void *value,
4138 size_t size, int flags)
4139{
4140 struct shmem_inode_info *info = SHMEM_I(inode);
4141 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
4142 struct simple_xattr *old_xattr;
4143 size_t ispace = 0;
4144
4145 name = xattr_full_name(handler, name);
4146 if (value && sbinfo->max_inodes) {
4147 ispace = simple_xattr_space(name, size);
4148 raw_spin_lock(&sbinfo->stat_lock);
4149 if (sbinfo->free_ispace < ispace)
4150 ispace = 0;
4151 else
4152 sbinfo->free_ispace -= ispace;
4153 raw_spin_unlock(&sbinfo->stat_lock);
4154 if (!ispace)
4155 return -ENOSPC;
4156 }
4157
4158 old_xattr = simple_xattr_set(&info->xattrs, name, value, size, flags);
4159 if (!IS_ERR(old_xattr)) {
4160 ispace = 0;
4161 if (old_xattr && sbinfo->max_inodes)
4162 ispace = simple_xattr_space(old_xattr->name,
4163 old_xattr->size);
4164 simple_xattr_free(old_xattr);
4165 old_xattr = NULL;
4166 inode_set_ctime_current(inode);
4167 inode_inc_iversion(inode);
4168 }
4169 if (ispace) {
4170 raw_spin_lock(&sbinfo->stat_lock);
4171 sbinfo->free_ispace += ispace;
4172 raw_spin_unlock(&sbinfo->stat_lock);
4173 }
4174 return PTR_ERR(old_xattr);
4175}
4176
4177static const struct xattr_handler shmem_security_xattr_handler = {
4178 .prefix = XATTR_SECURITY_PREFIX,
4179 .get = shmem_xattr_handler_get,
4180 .set = shmem_xattr_handler_set,
4181};
4182
4183static const struct xattr_handler shmem_trusted_xattr_handler = {
4184 .prefix = XATTR_TRUSTED_PREFIX,
4185 .get = shmem_xattr_handler_get,
4186 .set = shmem_xattr_handler_set,
4187};
4188
4189static const struct xattr_handler shmem_user_xattr_handler = {
4190 .prefix = XATTR_USER_PREFIX,
4191 .get = shmem_xattr_handler_get,
4192 .set = shmem_xattr_handler_set,
4193};
4194
4195static const struct xattr_handler * const shmem_xattr_handlers[] = {
4196 &shmem_security_xattr_handler,
4197 &shmem_trusted_xattr_handler,
4198 &shmem_user_xattr_handler,
4199 NULL
4200};
4201
4202static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
4203{
4204 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
4205 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
4206}
4207#endif /* CONFIG_TMPFS_XATTR */
4208
4209static const struct inode_operations shmem_short_symlink_operations = {
4210 .getattr = shmem_getattr,
4211 .setattr = shmem_setattr,
4212 .get_link = simple_get_link,
4213#ifdef CONFIG_TMPFS_XATTR
4214 .listxattr = shmem_listxattr,
4215#endif
4216};
4217
4218static const struct inode_operations shmem_symlink_inode_operations = {
4219 .getattr = shmem_getattr,
4220 .setattr = shmem_setattr,
4221 .get_link = shmem_get_link,
4222#ifdef CONFIG_TMPFS_XATTR
4223 .listxattr = shmem_listxattr,
4224#endif
4225};
4226
4227static struct dentry *shmem_get_parent(struct dentry *child)
4228{
4229 return ERR_PTR(-ESTALE);
4230}
4231
4232static int shmem_match(struct inode *ino, void *vfh)
4233{
4234 __u32 *fh = vfh;
4235 __u64 inum = fh[2];
4236 inum = (inum << 32) | fh[1];
4237 return ino->i_ino == inum && fh[0] == ino->i_generation;
4238}
4239
4240/* Find any alias of inode, but prefer a hashed alias */
4241static struct dentry *shmem_find_alias(struct inode *inode)
4242{
4243 struct dentry *alias = d_find_alias(inode);
4244
4245 return alias ?: d_find_any_alias(inode);
4246}
4247
4248static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
4249 struct fid *fid, int fh_len, int fh_type)
4250{
4251 struct inode *inode;
4252 struct dentry *dentry = NULL;
4253 u64 inum;
4254
4255 if (fh_len < 3)
4256 return NULL;
4257
4258 inum = fid->raw[2];
4259 inum = (inum << 32) | fid->raw[1];
4260
4261 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
4262 shmem_match, fid->raw);
4263 if (inode) {
4264 dentry = shmem_find_alias(inode);
4265 iput(inode);
4266 }
4267
4268 return dentry;
4269}
4270
4271static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
4272 struct inode *parent)
4273{
4274 if (*len < 3) {
4275 *len = 3;
4276 return FILEID_INVALID;
4277 }
4278
4279 if (inode_unhashed(inode)) {
4280 /* Unfortunately insert_inode_hash is not idempotent,
4281 * so as we hash inodes here rather than at creation
4282 * time, we need a lock to ensure we only try
4283 * to do it once
4284 */
4285 static DEFINE_SPINLOCK(lock);
4286 spin_lock(&lock);
4287 if (inode_unhashed(inode))
4288 __insert_inode_hash(inode,
4289 inode->i_ino + inode->i_generation);
4290 spin_unlock(&lock);
4291 }
4292
4293 fh[0] = inode->i_generation;
4294 fh[1] = inode->i_ino;
4295 fh[2] = ((__u64)inode->i_ino) >> 32;
4296
4297 *len = 3;
4298 return 1;
4299}
4300
4301static const struct export_operations shmem_export_ops = {
4302 .get_parent = shmem_get_parent,
4303 .encode_fh = shmem_encode_fh,
4304 .fh_to_dentry = shmem_fh_to_dentry,
4305};
4306
4307enum shmem_param {
4308 Opt_gid,
4309 Opt_huge,
4310 Opt_mode,
4311 Opt_mpol,
4312 Opt_nr_blocks,
4313 Opt_nr_inodes,
4314 Opt_size,
4315 Opt_uid,
4316 Opt_inode32,
4317 Opt_inode64,
4318 Opt_noswap,
4319 Opt_quota,
4320 Opt_usrquota,
4321 Opt_grpquota,
4322 Opt_usrquota_block_hardlimit,
4323 Opt_usrquota_inode_hardlimit,
4324 Opt_grpquota_block_hardlimit,
4325 Opt_grpquota_inode_hardlimit,
4326 Opt_casefold_version,
4327 Opt_casefold,
4328 Opt_strict_encoding,
4329};
4330
4331static const struct constant_table shmem_param_enums_huge[] = {
4332 {"never", SHMEM_HUGE_NEVER },
4333 {"always", SHMEM_HUGE_ALWAYS },
4334 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
4335 {"advise", SHMEM_HUGE_ADVISE },
4336 {}
4337};
4338
4339const struct fs_parameter_spec shmem_fs_parameters[] = {
4340 fsparam_gid ("gid", Opt_gid),
4341 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
4342 fsparam_u32oct("mode", Opt_mode),
4343 fsparam_string("mpol", Opt_mpol),
4344 fsparam_string("nr_blocks", Opt_nr_blocks),
4345 fsparam_string("nr_inodes", Opt_nr_inodes),
4346 fsparam_string("size", Opt_size),
4347 fsparam_uid ("uid", Opt_uid),
4348 fsparam_flag ("inode32", Opt_inode32),
4349 fsparam_flag ("inode64", Opt_inode64),
4350 fsparam_flag ("noswap", Opt_noswap),
4351#ifdef CONFIG_TMPFS_QUOTA
4352 fsparam_flag ("quota", Opt_quota),
4353 fsparam_flag ("usrquota", Opt_usrquota),
4354 fsparam_flag ("grpquota", Opt_grpquota),
4355 fsparam_string("usrquota_block_hardlimit", Opt_usrquota_block_hardlimit),
4356 fsparam_string("usrquota_inode_hardlimit", Opt_usrquota_inode_hardlimit),
4357 fsparam_string("grpquota_block_hardlimit", Opt_grpquota_block_hardlimit),
4358 fsparam_string("grpquota_inode_hardlimit", Opt_grpquota_inode_hardlimit),
4359#endif
4360 fsparam_string("casefold", Opt_casefold_version),
4361 fsparam_flag ("casefold", Opt_casefold),
4362 fsparam_flag ("strict_encoding", Opt_strict_encoding),
4363 {}
4364};
4365
4366#if IS_ENABLED(CONFIG_UNICODE)
4367static int shmem_parse_opt_casefold(struct fs_context *fc, struct fs_parameter *param,
4368 bool latest_version)
4369{
4370 struct shmem_options *ctx = fc->fs_private;
4371 int version = UTF8_LATEST;
4372 struct unicode_map *encoding;
4373 char *version_str = param->string + 5;
4374
4375 if (!latest_version) {
4376 if (strncmp(param->string, "utf8-", 5))
4377 return invalfc(fc, "Only UTF-8 encodings are supported "
4378 "in the format: utf8-<version number>");
4379
4380 version = utf8_parse_version(version_str);
4381 if (version < 0)
4382 return invalfc(fc, "Invalid UTF-8 version: %s", version_str);
4383 }
4384
4385 encoding = utf8_load(version);
4386
4387 if (IS_ERR(encoding)) {
4388 return invalfc(fc, "Failed loading UTF-8 version: utf8-%u.%u.%u\n",
4389 unicode_major(version), unicode_minor(version),
4390 unicode_rev(version));
4391 }
4392
4393 pr_info("tmpfs: Using encoding : utf8-%u.%u.%u\n",
4394 unicode_major(version), unicode_minor(version), unicode_rev(version));
4395
4396 ctx->encoding = encoding;
4397
4398 return 0;
4399}
4400#else
4401static int shmem_parse_opt_casefold(struct fs_context *fc, struct fs_parameter *param,
4402 bool latest_version)
4403{
4404 return invalfc(fc, "tmpfs: Kernel not built with CONFIG_UNICODE\n");
4405}
4406#endif
4407
4408static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
4409{
4410 struct shmem_options *ctx = fc->fs_private;
4411 struct fs_parse_result result;
4412 unsigned long long size;
4413 char *rest;
4414 int opt;
4415 kuid_t kuid;
4416 kgid_t kgid;
4417
4418 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
4419 if (opt < 0)
4420 return opt;
4421
4422 switch (opt) {
4423 case Opt_size:
4424 size = memparse(param->string, &rest);
4425 if (*rest == '%') {
4426 size <<= PAGE_SHIFT;
4427 size *= totalram_pages();
4428 do_div(size, 100);
4429 rest++;
4430 }
4431 if (*rest)
4432 goto bad_value;
4433 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
4434 ctx->seen |= SHMEM_SEEN_BLOCKS;
4435 break;
4436 case Opt_nr_blocks:
4437 ctx->blocks = memparse(param->string, &rest);
4438 if (*rest || ctx->blocks > LONG_MAX)
4439 goto bad_value;
4440 ctx->seen |= SHMEM_SEEN_BLOCKS;
4441 break;
4442 case Opt_nr_inodes:
4443 ctx->inodes = memparse(param->string, &rest);
4444 if (*rest || ctx->inodes > ULONG_MAX / BOGO_INODE_SIZE)
4445 goto bad_value;
4446 ctx->seen |= SHMEM_SEEN_INODES;
4447 break;
4448 case Opt_mode:
4449 ctx->mode = result.uint_32 & 07777;
4450 break;
4451 case Opt_uid:
4452 kuid = result.uid;
4453
4454 /*
4455 * The requested uid must be representable in the
4456 * filesystem's idmapping.
4457 */
4458 if (!kuid_has_mapping(fc->user_ns, kuid))
4459 goto bad_value;
4460
4461 ctx->uid = kuid;
4462 break;
4463 case Opt_gid:
4464 kgid = result.gid;
4465
4466 /*
4467 * The requested gid must be representable in the
4468 * filesystem's idmapping.
4469 */
4470 if (!kgid_has_mapping(fc->user_ns, kgid))
4471 goto bad_value;
4472
4473 ctx->gid = kgid;
4474 break;
4475 case Opt_huge:
4476 ctx->huge = result.uint_32;
4477 if (ctx->huge != SHMEM_HUGE_NEVER &&
4478 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
4479 has_transparent_hugepage()))
4480 goto unsupported_parameter;
4481 ctx->seen |= SHMEM_SEEN_HUGE;
4482 break;
4483 case Opt_mpol:
4484 if (IS_ENABLED(CONFIG_NUMA)) {
4485 mpol_put(ctx->mpol);
4486 ctx->mpol = NULL;
4487 if (mpol_parse_str(param->string, &ctx->mpol))
4488 goto bad_value;
4489 break;
4490 }
4491 goto unsupported_parameter;
4492 case Opt_inode32:
4493 ctx->full_inums = false;
4494 ctx->seen |= SHMEM_SEEN_INUMS;
4495 break;
4496 case Opt_inode64:
4497 if (sizeof(ino_t) < 8) {
4498 return invalfc(fc,
4499 "Cannot use inode64 with <64bit inums in kernel\n");
4500 }
4501 ctx->full_inums = true;
4502 ctx->seen |= SHMEM_SEEN_INUMS;
4503 break;
4504 case Opt_noswap:
4505 if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN)) {
4506 return invalfc(fc,
4507 "Turning off swap in unprivileged tmpfs mounts unsupported");
4508 }
4509 ctx->noswap = true;
4510 ctx->seen |= SHMEM_SEEN_NOSWAP;
4511 break;
4512 case Opt_quota:
4513 if (fc->user_ns != &init_user_ns)
4514 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4515 ctx->seen |= SHMEM_SEEN_QUOTA;
4516 ctx->quota_types |= (QTYPE_MASK_USR | QTYPE_MASK_GRP);
4517 break;
4518 case Opt_usrquota:
4519 if (fc->user_ns != &init_user_ns)
4520 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4521 ctx->seen |= SHMEM_SEEN_QUOTA;
4522 ctx->quota_types |= QTYPE_MASK_USR;
4523 break;
4524 case Opt_grpquota:
4525 if (fc->user_ns != &init_user_ns)
4526 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4527 ctx->seen |= SHMEM_SEEN_QUOTA;
4528 ctx->quota_types |= QTYPE_MASK_GRP;
4529 break;
4530 case Opt_usrquota_block_hardlimit:
4531 size = memparse(param->string, &rest);
4532 if (*rest || !size)
4533 goto bad_value;
4534 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4535 return invalfc(fc,
4536 "User quota block hardlimit too large.");
4537 ctx->qlimits.usrquota_bhardlimit = size;
4538 break;
4539 case Opt_grpquota_block_hardlimit:
4540 size = memparse(param->string, &rest);
4541 if (*rest || !size)
4542 goto bad_value;
4543 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4544 return invalfc(fc,
4545 "Group quota block hardlimit too large.");
4546 ctx->qlimits.grpquota_bhardlimit = size;
4547 break;
4548 case Opt_usrquota_inode_hardlimit:
4549 size = memparse(param->string, &rest);
4550 if (*rest || !size)
4551 goto bad_value;
4552 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4553 return invalfc(fc,
4554 "User quota inode hardlimit too large.");
4555 ctx->qlimits.usrquota_ihardlimit = size;
4556 break;
4557 case Opt_grpquota_inode_hardlimit:
4558 size = memparse(param->string, &rest);
4559 if (*rest || !size)
4560 goto bad_value;
4561 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4562 return invalfc(fc,
4563 "Group quota inode hardlimit too large.");
4564 ctx->qlimits.grpquota_ihardlimit = size;
4565 break;
4566 case Opt_casefold_version:
4567 return shmem_parse_opt_casefold(fc, param, false);
4568 case Opt_casefold:
4569 return shmem_parse_opt_casefold(fc, param, true);
4570 case Opt_strict_encoding:
4571#if IS_ENABLED(CONFIG_UNICODE)
4572 ctx->strict_encoding = true;
4573 break;
4574#else
4575 return invalfc(fc, "tmpfs: Kernel not built with CONFIG_UNICODE\n");
4576#endif
4577 }
4578 return 0;
4579
4580unsupported_parameter:
4581 return invalfc(fc, "Unsupported parameter '%s'", param->key);
4582bad_value:
4583 return invalfc(fc, "Bad value for '%s'", param->key);
4584}
4585
4586static int shmem_parse_options(struct fs_context *fc, void *data)
4587{
4588 char *options = data;
4589
4590 if (options) {
4591 int err = security_sb_eat_lsm_opts(options, &fc->security);
4592 if (err)
4593 return err;
4594 }
4595
4596 while (options != NULL) {
4597 char *this_char = options;
4598 for (;;) {
4599 /*
4600 * NUL-terminate this option: unfortunately,
4601 * mount options form a comma-separated list,
4602 * but mpol's nodelist may also contain commas.
4603 */
4604 options = strchr(options, ',');
4605 if (options == NULL)
4606 break;
4607 options++;
4608 if (!isdigit(*options)) {
4609 options[-1] = '\0';
4610 break;
4611 }
4612 }
4613 if (*this_char) {
4614 char *value = strchr(this_char, '=');
4615 size_t len = 0;
4616 int err;
4617
4618 if (value) {
4619 *value++ = '\0';
4620 len = strlen(value);
4621 }
4622 err = vfs_parse_fs_string(fc, this_char, value, len);
4623 if (err < 0)
4624 return err;
4625 }
4626 }
4627 return 0;
4628}
4629
4630/*
4631 * Reconfigure a shmem filesystem.
4632 */
4633static int shmem_reconfigure(struct fs_context *fc)
4634{
4635 struct shmem_options *ctx = fc->fs_private;
4636 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
4637 unsigned long used_isp;
4638 struct mempolicy *mpol = NULL;
4639 const char *err;
4640
4641 raw_spin_lock(&sbinfo->stat_lock);
4642 used_isp = sbinfo->max_inodes * BOGO_INODE_SIZE - sbinfo->free_ispace;
4643
4644 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
4645 if (!sbinfo->max_blocks) {
4646 err = "Cannot retroactively limit size";
4647 goto out;
4648 }
4649 if (percpu_counter_compare(&sbinfo->used_blocks,
4650 ctx->blocks) > 0) {
4651 err = "Too small a size for current use";
4652 goto out;
4653 }
4654 }
4655 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
4656 if (!sbinfo->max_inodes) {
4657 err = "Cannot retroactively limit inodes";
4658 goto out;
4659 }
4660 if (ctx->inodes * BOGO_INODE_SIZE < used_isp) {
4661 err = "Too few inodes for current use";
4662 goto out;
4663 }
4664 }
4665
4666 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
4667 sbinfo->next_ino > UINT_MAX) {
4668 err = "Current inum too high to switch to 32-bit inums";
4669 goto out;
4670 }
4671 if ((ctx->seen & SHMEM_SEEN_NOSWAP) && ctx->noswap && !sbinfo->noswap) {
4672 err = "Cannot disable swap on remount";
4673 goto out;
4674 }
4675 if (!(ctx->seen & SHMEM_SEEN_NOSWAP) && !ctx->noswap && sbinfo->noswap) {
4676 err = "Cannot enable swap on remount if it was disabled on first mount";
4677 goto out;
4678 }
4679
4680 if (ctx->seen & SHMEM_SEEN_QUOTA &&
4681 !sb_any_quota_loaded(fc->root->d_sb)) {
4682 err = "Cannot enable quota on remount";
4683 goto out;
4684 }
4685
4686#ifdef CONFIG_TMPFS_QUOTA
4687#define CHANGED_LIMIT(name) \
4688 (ctx->qlimits.name## hardlimit && \
4689 (ctx->qlimits.name## hardlimit != sbinfo->qlimits.name## hardlimit))
4690
4691 if (CHANGED_LIMIT(usrquota_b) || CHANGED_LIMIT(usrquota_i) ||
4692 CHANGED_LIMIT(grpquota_b) || CHANGED_LIMIT(grpquota_i)) {
4693 err = "Cannot change global quota limit on remount";
4694 goto out;
4695 }
4696#endif /* CONFIG_TMPFS_QUOTA */
4697
4698 if (ctx->seen & SHMEM_SEEN_HUGE)
4699 sbinfo->huge = ctx->huge;
4700 if (ctx->seen & SHMEM_SEEN_INUMS)
4701 sbinfo->full_inums = ctx->full_inums;
4702 if (ctx->seen & SHMEM_SEEN_BLOCKS)
4703 sbinfo->max_blocks = ctx->blocks;
4704 if (ctx->seen & SHMEM_SEEN_INODES) {
4705 sbinfo->max_inodes = ctx->inodes;
4706 sbinfo->free_ispace = ctx->inodes * BOGO_INODE_SIZE - used_isp;
4707 }
4708
4709 /*
4710 * Preserve previous mempolicy unless mpol remount option was specified.
4711 */
4712 if (ctx->mpol) {
4713 mpol = sbinfo->mpol;
4714 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
4715 ctx->mpol = NULL;
4716 }
4717
4718 if (ctx->noswap)
4719 sbinfo->noswap = true;
4720
4721 raw_spin_unlock(&sbinfo->stat_lock);
4722 mpol_put(mpol);
4723 return 0;
4724out:
4725 raw_spin_unlock(&sbinfo->stat_lock);
4726 return invalfc(fc, "%s", err);
4727}
4728
4729static int shmem_show_options(struct seq_file *seq, struct dentry *root)
4730{
4731 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
4732 struct mempolicy *mpol;
4733
4734 if (sbinfo->max_blocks != shmem_default_max_blocks())
4735 seq_printf(seq, ",size=%luk", K(sbinfo->max_blocks));
4736 if (sbinfo->max_inodes != shmem_default_max_inodes())
4737 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
4738 if (sbinfo->mode != (0777 | S_ISVTX))
4739 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
4740 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
4741 seq_printf(seq, ",uid=%u",
4742 from_kuid_munged(&init_user_ns, sbinfo->uid));
4743 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
4744 seq_printf(seq, ",gid=%u",
4745 from_kgid_munged(&init_user_ns, sbinfo->gid));
4746
4747 /*
4748 * Showing inode{64,32} might be useful even if it's the system default,
4749 * since then people don't have to resort to checking both here and
4750 * /proc/config.gz to confirm 64-bit inums were successfully applied
4751 * (which may not even exist if IKCONFIG_PROC isn't enabled).
4752 *
4753 * We hide it when inode64 isn't the default and we are using 32-bit
4754 * inodes, since that probably just means the feature isn't even under
4755 * consideration.
4756 *
4757 * As such:
4758 *
4759 * +-----------------+-----------------+
4760 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
4761 * +------------------+-----------------+-----------------+
4762 * | full_inums=true | show | show |
4763 * | full_inums=false | show | hide |
4764 * +------------------+-----------------+-----------------+
4765 *
4766 */
4767 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
4768 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
4769#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4770 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
4771 if (sbinfo->huge)
4772 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
4773#endif
4774 mpol = shmem_get_sbmpol(sbinfo);
4775 shmem_show_mpol(seq, mpol);
4776 mpol_put(mpol);
4777 if (sbinfo->noswap)
4778 seq_printf(seq, ",noswap");
4779#ifdef CONFIG_TMPFS_QUOTA
4780 if (sb_has_quota_active(root->d_sb, USRQUOTA))
4781 seq_printf(seq, ",usrquota");
4782 if (sb_has_quota_active(root->d_sb, GRPQUOTA))
4783 seq_printf(seq, ",grpquota");
4784 if (sbinfo->qlimits.usrquota_bhardlimit)
4785 seq_printf(seq, ",usrquota_block_hardlimit=%lld",
4786 sbinfo->qlimits.usrquota_bhardlimit);
4787 if (sbinfo->qlimits.grpquota_bhardlimit)
4788 seq_printf(seq, ",grpquota_block_hardlimit=%lld",
4789 sbinfo->qlimits.grpquota_bhardlimit);
4790 if (sbinfo->qlimits.usrquota_ihardlimit)
4791 seq_printf(seq, ",usrquota_inode_hardlimit=%lld",
4792 sbinfo->qlimits.usrquota_ihardlimit);
4793 if (sbinfo->qlimits.grpquota_ihardlimit)
4794 seq_printf(seq, ",grpquota_inode_hardlimit=%lld",
4795 sbinfo->qlimits.grpquota_ihardlimit);
4796#endif
4797 return 0;
4798}
4799
4800#endif /* CONFIG_TMPFS */
4801
4802static void shmem_put_super(struct super_block *sb)
4803{
4804 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
4805
4806#if IS_ENABLED(CONFIG_UNICODE)
4807 if (sb->s_encoding)
4808 utf8_unload(sb->s_encoding);
4809#endif
4810
4811#ifdef CONFIG_TMPFS_QUOTA
4812 shmem_disable_quotas(sb);
4813#endif
4814 free_percpu(sbinfo->ino_batch);
4815 percpu_counter_destroy(&sbinfo->used_blocks);
4816 mpol_put(sbinfo->mpol);
4817 kfree(sbinfo);
4818 sb->s_fs_info = NULL;
4819}
4820
4821#if IS_ENABLED(CONFIG_UNICODE) && defined(CONFIG_TMPFS)
4822static const struct dentry_operations shmem_ci_dentry_ops = {
4823 .d_hash = generic_ci_d_hash,
4824 .d_compare = generic_ci_d_compare,
4825 .d_delete = always_delete_dentry,
4826};
4827#endif
4828
4829static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
4830{
4831 struct shmem_options *ctx = fc->fs_private;
4832 struct inode *inode;
4833 struct shmem_sb_info *sbinfo;
4834 int error = -ENOMEM;
4835
4836 /* Round up to L1_CACHE_BYTES to resist false sharing */
4837 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
4838 L1_CACHE_BYTES), GFP_KERNEL);
4839 if (!sbinfo)
4840 return error;
4841
4842 sb->s_fs_info = sbinfo;
4843
4844#ifdef CONFIG_TMPFS
4845 /*
4846 * Per default we only allow half of the physical ram per
4847 * tmpfs instance, limiting inodes to one per page of lowmem;
4848 * but the internal instance is left unlimited.
4849 */
4850 if (!(sb->s_flags & SB_KERNMOUNT)) {
4851 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
4852 ctx->blocks = shmem_default_max_blocks();
4853 if (!(ctx->seen & SHMEM_SEEN_INODES))
4854 ctx->inodes = shmem_default_max_inodes();
4855 if (!(ctx->seen & SHMEM_SEEN_INUMS))
4856 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
4857 sbinfo->noswap = ctx->noswap;
4858 } else {
4859 sb->s_flags |= SB_NOUSER;
4860 }
4861 sb->s_export_op = &shmem_export_ops;
4862 sb->s_flags |= SB_NOSEC | SB_I_VERSION;
4863
4864#if IS_ENABLED(CONFIG_UNICODE)
4865 if (!ctx->encoding && ctx->strict_encoding) {
4866 pr_err("tmpfs: strict_encoding option without encoding is forbidden\n");
4867 error = -EINVAL;
4868 goto failed;
4869 }
4870
4871 if (ctx->encoding) {
4872 sb->s_encoding = ctx->encoding;
4873 sb->s_d_op = &shmem_ci_dentry_ops;
4874 if (ctx->strict_encoding)
4875 sb->s_encoding_flags = SB_ENC_STRICT_MODE_FL;
4876 }
4877#endif
4878
4879#else
4880 sb->s_flags |= SB_NOUSER;
4881#endif /* CONFIG_TMPFS */
4882 sbinfo->max_blocks = ctx->blocks;
4883 sbinfo->max_inodes = ctx->inodes;
4884 sbinfo->free_ispace = sbinfo->max_inodes * BOGO_INODE_SIZE;
4885 if (sb->s_flags & SB_KERNMOUNT) {
4886 sbinfo->ino_batch = alloc_percpu(ino_t);
4887 if (!sbinfo->ino_batch)
4888 goto failed;
4889 }
4890 sbinfo->uid = ctx->uid;
4891 sbinfo->gid = ctx->gid;
4892 sbinfo->full_inums = ctx->full_inums;
4893 sbinfo->mode = ctx->mode;
4894 sbinfo->huge = ctx->huge;
4895 sbinfo->mpol = ctx->mpol;
4896 ctx->mpol = NULL;
4897
4898 raw_spin_lock_init(&sbinfo->stat_lock);
4899 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
4900 goto failed;
4901 spin_lock_init(&sbinfo->shrinklist_lock);
4902 INIT_LIST_HEAD(&sbinfo->shrinklist);
4903
4904 sb->s_maxbytes = MAX_LFS_FILESIZE;
4905 sb->s_blocksize = PAGE_SIZE;
4906 sb->s_blocksize_bits = PAGE_SHIFT;
4907 sb->s_magic = TMPFS_MAGIC;
4908 sb->s_op = &shmem_ops;
4909 sb->s_time_gran = 1;
4910#ifdef CONFIG_TMPFS_XATTR
4911 sb->s_xattr = shmem_xattr_handlers;
4912#endif
4913#ifdef CONFIG_TMPFS_POSIX_ACL
4914 sb->s_flags |= SB_POSIXACL;
4915#endif
4916 uuid_t uuid;
4917 uuid_gen(&uuid);
4918 super_set_uuid(sb, uuid.b, sizeof(uuid));
4919
4920#ifdef CONFIG_TMPFS_QUOTA
4921 if (ctx->seen & SHMEM_SEEN_QUOTA) {
4922 sb->dq_op = &shmem_quota_operations;
4923 sb->s_qcop = &dquot_quotactl_sysfile_ops;
4924 sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
4925
4926 /* Copy the default limits from ctx into sbinfo */
4927 memcpy(&sbinfo->qlimits, &ctx->qlimits,
4928 sizeof(struct shmem_quota_limits));
4929
4930 if (shmem_enable_quotas(sb, ctx->quota_types))
4931 goto failed;
4932 }
4933#endif /* CONFIG_TMPFS_QUOTA */
4934
4935 inode = shmem_get_inode(&nop_mnt_idmap, sb, NULL,
4936 S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
4937 if (IS_ERR(inode)) {
4938 error = PTR_ERR(inode);
4939 goto failed;
4940 }
4941 inode->i_uid = sbinfo->uid;
4942 inode->i_gid = sbinfo->gid;
4943 sb->s_root = d_make_root(inode);
4944 if (!sb->s_root)
4945 goto failed;
4946 return 0;
4947
4948failed:
4949 shmem_put_super(sb);
4950 return error;
4951}
4952
4953static int shmem_get_tree(struct fs_context *fc)
4954{
4955 return get_tree_nodev(fc, shmem_fill_super);
4956}
4957
4958static void shmem_free_fc(struct fs_context *fc)
4959{
4960 struct shmem_options *ctx = fc->fs_private;
4961
4962 if (ctx) {
4963 mpol_put(ctx->mpol);
4964 kfree(ctx);
4965 }
4966}
4967
4968static const struct fs_context_operations shmem_fs_context_ops = {
4969 .free = shmem_free_fc,
4970 .get_tree = shmem_get_tree,
4971#ifdef CONFIG_TMPFS
4972 .parse_monolithic = shmem_parse_options,
4973 .parse_param = shmem_parse_one,
4974 .reconfigure = shmem_reconfigure,
4975#endif
4976};
4977
4978static struct kmem_cache *shmem_inode_cachep __ro_after_init;
4979
4980static struct inode *shmem_alloc_inode(struct super_block *sb)
4981{
4982 struct shmem_inode_info *info;
4983 info = alloc_inode_sb(sb, shmem_inode_cachep, GFP_KERNEL);
4984 if (!info)
4985 return NULL;
4986 return &info->vfs_inode;
4987}
4988
4989static void shmem_free_in_core_inode(struct inode *inode)
4990{
4991 if (S_ISLNK(inode->i_mode))
4992 kfree(inode->i_link);
4993 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
4994}
4995
4996static void shmem_destroy_inode(struct inode *inode)
4997{
4998 if (S_ISREG(inode->i_mode))
4999 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
5000 if (S_ISDIR(inode->i_mode))
5001 simple_offset_destroy(shmem_get_offset_ctx(inode));
5002}
5003
5004static void shmem_init_inode(void *foo)
5005{
5006 struct shmem_inode_info *info = foo;
5007 inode_init_once(&info->vfs_inode);
5008}
5009
5010static void __init shmem_init_inodecache(void)
5011{
5012 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
5013 sizeof(struct shmem_inode_info),
5014 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
5015}
5016
5017static void __init shmem_destroy_inodecache(void)
5018{
5019 kmem_cache_destroy(shmem_inode_cachep);
5020}
5021
5022/* Keep the page in page cache instead of truncating it */
5023static int shmem_error_remove_folio(struct address_space *mapping,
5024 struct folio *folio)
5025{
5026 return 0;
5027}
5028
5029static const struct address_space_operations shmem_aops = {
5030 .writepage = shmem_writepage,
5031 .dirty_folio = noop_dirty_folio,
5032#ifdef CONFIG_TMPFS
5033 .write_begin = shmem_write_begin,
5034 .write_end = shmem_write_end,
5035#endif
5036#ifdef CONFIG_MIGRATION
5037 .migrate_folio = migrate_folio,
5038#endif
5039 .error_remove_folio = shmem_error_remove_folio,
5040};
5041
5042static const struct file_operations shmem_file_operations = {
5043 .mmap = shmem_mmap,
5044 .open = shmem_file_open,
5045 .get_unmapped_area = shmem_get_unmapped_area,
5046#ifdef CONFIG_TMPFS
5047 .llseek = shmem_file_llseek,
5048 .read_iter = shmem_file_read_iter,
5049 .write_iter = shmem_file_write_iter,
5050 .fsync = noop_fsync,
5051 .splice_read = shmem_file_splice_read,
5052 .splice_write = iter_file_splice_write,
5053 .fallocate = shmem_fallocate,
5054#endif
5055};
5056
5057static const struct inode_operations shmem_inode_operations = {
5058 .getattr = shmem_getattr,
5059 .setattr = shmem_setattr,
5060#ifdef CONFIG_TMPFS_XATTR
5061 .listxattr = shmem_listxattr,
5062 .set_acl = simple_set_acl,
5063 .fileattr_get = shmem_fileattr_get,
5064 .fileattr_set = shmem_fileattr_set,
5065#endif
5066};
5067
5068static const struct inode_operations shmem_dir_inode_operations = {
5069#ifdef CONFIG_TMPFS
5070 .getattr = shmem_getattr,
5071 .create = shmem_create,
5072 .lookup = simple_lookup,
5073 .link = shmem_link,
5074 .unlink = shmem_unlink,
5075 .symlink = shmem_symlink,
5076 .mkdir = shmem_mkdir,
5077 .rmdir = shmem_rmdir,
5078 .mknod = shmem_mknod,
5079 .rename = shmem_rename2,
5080 .tmpfile = shmem_tmpfile,
5081 .get_offset_ctx = shmem_get_offset_ctx,
5082#endif
5083#ifdef CONFIG_TMPFS_XATTR
5084 .listxattr = shmem_listxattr,
5085 .fileattr_get = shmem_fileattr_get,
5086 .fileattr_set = shmem_fileattr_set,
5087#endif
5088#ifdef CONFIG_TMPFS_POSIX_ACL
5089 .setattr = shmem_setattr,
5090 .set_acl = simple_set_acl,
5091#endif
5092};
5093
5094static const struct inode_operations shmem_special_inode_operations = {
5095 .getattr = shmem_getattr,
5096#ifdef CONFIG_TMPFS_XATTR
5097 .listxattr = shmem_listxattr,
5098#endif
5099#ifdef CONFIG_TMPFS_POSIX_ACL
5100 .setattr = shmem_setattr,
5101 .set_acl = simple_set_acl,
5102#endif
5103};
5104
5105static const struct super_operations shmem_ops = {
5106 .alloc_inode = shmem_alloc_inode,
5107 .free_inode = shmem_free_in_core_inode,
5108 .destroy_inode = shmem_destroy_inode,
5109#ifdef CONFIG_TMPFS
5110 .statfs = shmem_statfs,
5111 .show_options = shmem_show_options,
5112#endif
5113#ifdef CONFIG_TMPFS_QUOTA
5114 .get_dquots = shmem_get_dquots,
5115#endif
5116 .evict_inode = shmem_evict_inode,
5117 .drop_inode = generic_delete_inode,
5118 .put_super = shmem_put_super,
5119#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5120 .nr_cached_objects = shmem_unused_huge_count,
5121 .free_cached_objects = shmem_unused_huge_scan,
5122#endif
5123};
5124
5125static const struct vm_operations_struct shmem_vm_ops = {
5126 .fault = shmem_fault,
5127 .map_pages = filemap_map_pages,
5128#ifdef CONFIG_NUMA
5129 .set_policy = shmem_set_policy,
5130 .get_policy = shmem_get_policy,
5131#endif
5132};
5133
5134static const struct vm_operations_struct shmem_anon_vm_ops = {
5135 .fault = shmem_fault,
5136 .map_pages = filemap_map_pages,
5137#ifdef CONFIG_NUMA
5138 .set_policy = shmem_set_policy,
5139 .get_policy = shmem_get_policy,
5140#endif
5141};
5142
5143int shmem_init_fs_context(struct fs_context *fc)
5144{
5145 struct shmem_options *ctx;
5146
5147 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
5148 if (!ctx)
5149 return -ENOMEM;
5150
5151 ctx->mode = 0777 | S_ISVTX;
5152 ctx->uid = current_fsuid();
5153 ctx->gid = current_fsgid();
5154
5155#if IS_ENABLED(CONFIG_UNICODE)
5156 ctx->encoding = NULL;
5157#endif
5158
5159 fc->fs_private = ctx;
5160 fc->ops = &shmem_fs_context_ops;
5161 return 0;
5162}
5163
5164static struct file_system_type shmem_fs_type = {
5165 .owner = THIS_MODULE,
5166 .name = "tmpfs",
5167 .init_fs_context = shmem_init_fs_context,
5168#ifdef CONFIG_TMPFS
5169 .parameters = shmem_fs_parameters,
5170#endif
5171 .kill_sb = kill_litter_super,
5172 .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP | FS_MGTIME,
5173};
5174
5175#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
5176
5177#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store) \
5178{ \
5179 .attr = { .name = __stringify(_name), .mode = _mode }, \
5180 .show = _show, \
5181 .store = _store, \
5182}
5183
5184#define TMPFS_ATTR_W(_name, _store) \
5185 static struct kobj_attribute tmpfs_attr_##_name = \
5186 __INIT_KOBJ_ATTR(_name, 0200, NULL, _store)
5187
5188#define TMPFS_ATTR_RW(_name, _show, _store) \
5189 static struct kobj_attribute tmpfs_attr_##_name = \
5190 __INIT_KOBJ_ATTR(_name, 0644, _show, _store)
5191
5192#define TMPFS_ATTR_RO(_name, _show) \
5193 static struct kobj_attribute tmpfs_attr_##_name = \
5194 __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
5195
5196#if IS_ENABLED(CONFIG_UNICODE)
5197static ssize_t casefold_show(struct kobject *kobj, struct kobj_attribute *a,
5198 char *buf)
5199{
5200 return sysfs_emit(buf, "supported\n");
5201}
5202TMPFS_ATTR_RO(casefold, casefold_show);
5203#endif
5204
5205static struct attribute *tmpfs_attributes[] = {
5206#if IS_ENABLED(CONFIG_UNICODE)
5207 &tmpfs_attr_casefold.attr,
5208#endif
5209 NULL
5210};
5211
5212static const struct attribute_group tmpfs_attribute_group = {
5213 .attrs = tmpfs_attributes,
5214 .name = "features"
5215};
5216
5217static struct kobject *tmpfs_kobj;
5218
5219static int __init tmpfs_sysfs_init(void)
5220{
5221 int ret;
5222
5223 tmpfs_kobj = kobject_create_and_add("tmpfs", fs_kobj);
5224 if (!tmpfs_kobj)
5225 return -ENOMEM;
5226
5227 ret = sysfs_create_group(tmpfs_kobj, &tmpfs_attribute_group);
5228 if (ret)
5229 kobject_put(tmpfs_kobj);
5230
5231 return ret;
5232}
5233#endif /* CONFIG_SYSFS && CONFIG_TMPFS */
5234
5235void __init shmem_init(void)
5236{
5237 int error;
5238
5239 shmem_init_inodecache();
5240
5241#ifdef CONFIG_TMPFS_QUOTA
5242 register_quota_format(&shmem_quota_format);
5243#endif
5244
5245 error = register_filesystem(&shmem_fs_type);
5246 if (error) {
5247 pr_err("Could not register tmpfs\n");
5248 goto out2;
5249 }
5250
5251 shm_mnt = kern_mount(&shmem_fs_type);
5252 if (IS_ERR(shm_mnt)) {
5253 error = PTR_ERR(shm_mnt);
5254 pr_err("Could not kern_mount tmpfs\n");
5255 goto out1;
5256 }
5257
5258#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
5259 error = tmpfs_sysfs_init();
5260 if (error) {
5261 pr_err("Could not init tmpfs sysfs\n");
5262 goto out1;
5263 }
5264#endif
5265
5266#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5267 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
5268 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
5269 else
5270 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
5271
5272 /*
5273 * Default to setting PMD-sized THP to inherit the global setting and
5274 * disable all other multi-size THPs.
5275 */
5276 if (!shmem_orders_configured)
5277 huge_shmem_orders_inherit = BIT(HPAGE_PMD_ORDER);
5278#endif
5279 return;
5280
5281out1:
5282 unregister_filesystem(&shmem_fs_type);
5283out2:
5284#ifdef CONFIG_TMPFS_QUOTA
5285 unregister_quota_format(&shmem_quota_format);
5286#endif
5287 shmem_destroy_inodecache();
5288 shm_mnt = ERR_PTR(error);
5289}
5290
5291#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
5292static ssize_t shmem_enabled_show(struct kobject *kobj,
5293 struct kobj_attribute *attr, char *buf)
5294{
5295 static const int values[] = {
5296 SHMEM_HUGE_ALWAYS,
5297 SHMEM_HUGE_WITHIN_SIZE,
5298 SHMEM_HUGE_ADVISE,
5299 SHMEM_HUGE_NEVER,
5300 SHMEM_HUGE_DENY,
5301 SHMEM_HUGE_FORCE,
5302 };
5303 int len = 0;
5304 int i;
5305
5306 for (i = 0; i < ARRAY_SIZE(values); i++) {
5307 len += sysfs_emit_at(buf, len,
5308 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
5309 i ? " " : "", shmem_format_huge(values[i]));
5310 }
5311 len += sysfs_emit_at(buf, len, "\n");
5312
5313 return len;
5314}
5315
5316static ssize_t shmem_enabled_store(struct kobject *kobj,
5317 struct kobj_attribute *attr, const char *buf, size_t count)
5318{
5319 char tmp[16];
5320 int huge, err;
5321
5322 if (count + 1 > sizeof(tmp))
5323 return -EINVAL;
5324 memcpy(tmp, buf, count);
5325 tmp[count] = '\0';
5326 if (count && tmp[count - 1] == '\n')
5327 tmp[count - 1] = '\0';
5328
5329 huge = shmem_parse_huge(tmp);
5330 if (huge == -EINVAL)
5331 return huge;
5332
5333 shmem_huge = huge;
5334 if (shmem_huge > SHMEM_HUGE_DENY)
5335 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
5336
5337 err = start_stop_khugepaged();
5338 return err ? err : count;
5339}
5340
5341struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
5342static DEFINE_SPINLOCK(huge_shmem_orders_lock);
5343
5344static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj,
5345 struct kobj_attribute *attr, char *buf)
5346{
5347 int order = to_thpsize(kobj)->order;
5348 const char *output;
5349
5350 if (test_bit(order, &huge_shmem_orders_always))
5351 output = "[always] inherit within_size advise never";
5352 else if (test_bit(order, &huge_shmem_orders_inherit))
5353 output = "always [inherit] within_size advise never";
5354 else if (test_bit(order, &huge_shmem_orders_within_size))
5355 output = "always inherit [within_size] advise never";
5356 else if (test_bit(order, &huge_shmem_orders_madvise))
5357 output = "always inherit within_size [advise] never";
5358 else
5359 output = "always inherit within_size advise [never]";
5360
5361 return sysfs_emit(buf, "%s\n", output);
5362}
5363
5364static ssize_t thpsize_shmem_enabled_store(struct kobject *kobj,
5365 struct kobj_attribute *attr,
5366 const char *buf, size_t count)
5367{
5368 int order = to_thpsize(kobj)->order;
5369 ssize_t ret = count;
5370
5371 if (sysfs_streq(buf, "always")) {
5372 spin_lock(&huge_shmem_orders_lock);
5373 clear_bit(order, &huge_shmem_orders_inherit);
5374 clear_bit(order, &huge_shmem_orders_madvise);
5375 clear_bit(order, &huge_shmem_orders_within_size);
5376 set_bit(order, &huge_shmem_orders_always);
5377 spin_unlock(&huge_shmem_orders_lock);
5378 } else if (sysfs_streq(buf, "inherit")) {
5379 /* Do not override huge allocation policy with non-PMD sized mTHP */
5380 if (shmem_huge == SHMEM_HUGE_FORCE &&
5381 order != HPAGE_PMD_ORDER)
5382 return -EINVAL;
5383
5384 spin_lock(&huge_shmem_orders_lock);
5385 clear_bit(order, &huge_shmem_orders_always);
5386 clear_bit(order, &huge_shmem_orders_madvise);
5387 clear_bit(order, &huge_shmem_orders_within_size);
5388 set_bit(order, &huge_shmem_orders_inherit);
5389 spin_unlock(&huge_shmem_orders_lock);
5390 } else if (sysfs_streq(buf, "within_size")) {
5391 spin_lock(&huge_shmem_orders_lock);
5392 clear_bit(order, &huge_shmem_orders_always);
5393 clear_bit(order, &huge_shmem_orders_inherit);
5394 clear_bit(order, &huge_shmem_orders_madvise);
5395 set_bit(order, &huge_shmem_orders_within_size);
5396 spin_unlock(&huge_shmem_orders_lock);
5397 } else if (sysfs_streq(buf, "advise")) {
5398 spin_lock(&huge_shmem_orders_lock);
5399 clear_bit(order, &huge_shmem_orders_always);
5400 clear_bit(order, &huge_shmem_orders_inherit);
5401 clear_bit(order, &huge_shmem_orders_within_size);
5402 set_bit(order, &huge_shmem_orders_madvise);
5403 spin_unlock(&huge_shmem_orders_lock);
5404 } else if (sysfs_streq(buf, "never")) {
5405 spin_lock(&huge_shmem_orders_lock);
5406 clear_bit(order, &huge_shmem_orders_always);
5407 clear_bit(order, &huge_shmem_orders_inherit);
5408 clear_bit(order, &huge_shmem_orders_within_size);
5409 clear_bit(order, &huge_shmem_orders_madvise);
5410 spin_unlock(&huge_shmem_orders_lock);
5411 } else {
5412 ret = -EINVAL;
5413 }
5414
5415 if (ret > 0) {
5416 int err = start_stop_khugepaged();
5417
5418 if (err)
5419 ret = err;
5420 }
5421 return ret;
5422}
5423
5424struct kobj_attribute thpsize_shmem_enabled_attr =
5425 __ATTR(shmem_enabled, 0644, thpsize_shmem_enabled_show, thpsize_shmem_enabled_store);
5426#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
5427
5428#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
5429
5430static int __init setup_transparent_hugepage_shmem(char *str)
5431{
5432 int huge;
5433
5434 huge = shmem_parse_huge(str);
5435 if (huge == -EINVAL) {
5436 pr_warn("transparent_hugepage_shmem= cannot parse, ignored\n");
5437 return huge;
5438 }
5439
5440 shmem_huge = huge;
5441 return 1;
5442}
5443__setup("transparent_hugepage_shmem=", setup_transparent_hugepage_shmem);
5444
5445static char str_dup[PAGE_SIZE] __initdata;
5446static int __init setup_thp_shmem(char *str)
5447{
5448 char *token, *range, *policy, *subtoken;
5449 unsigned long always, inherit, madvise, within_size;
5450 char *start_size, *end_size;
5451 int start, end, nr;
5452 char *p;
5453
5454 if (!str || strlen(str) + 1 > PAGE_SIZE)
5455 goto err;
5456 strscpy(str_dup, str);
5457
5458 always = huge_shmem_orders_always;
5459 inherit = huge_shmem_orders_inherit;
5460 madvise = huge_shmem_orders_madvise;
5461 within_size = huge_shmem_orders_within_size;
5462 p = str_dup;
5463 while ((token = strsep(&p, ";")) != NULL) {
5464 range = strsep(&token, ":");
5465 policy = token;
5466
5467 if (!policy)
5468 goto err;
5469
5470 while ((subtoken = strsep(&range, ",")) != NULL) {
5471 if (strchr(subtoken, '-')) {
5472 start_size = strsep(&subtoken, "-");
5473 end_size = subtoken;
5474
5475 start = get_order_from_str(start_size,
5476 THP_ORDERS_ALL_FILE_DEFAULT);
5477 end = get_order_from_str(end_size,
5478 THP_ORDERS_ALL_FILE_DEFAULT);
5479 } else {
5480 start_size = end_size = subtoken;
5481 start = end = get_order_from_str(subtoken,
5482 THP_ORDERS_ALL_FILE_DEFAULT);
5483 }
5484
5485 if (start == -EINVAL) {
5486 pr_err("invalid size %s in thp_shmem boot parameter\n",
5487 start_size);
5488 goto err;
5489 }
5490
5491 if (end == -EINVAL) {
5492 pr_err("invalid size %s in thp_shmem boot parameter\n",
5493 end_size);
5494 goto err;
5495 }
5496
5497 if (start < 0 || end < 0 || start > end)
5498 goto err;
5499
5500 nr = end - start + 1;
5501 if (!strcmp(policy, "always")) {
5502 bitmap_set(&always, start, nr);
5503 bitmap_clear(&inherit, start, nr);
5504 bitmap_clear(&madvise, start, nr);
5505 bitmap_clear(&within_size, start, nr);
5506 } else if (!strcmp(policy, "advise")) {
5507 bitmap_set(&madvise, start, nr);
5508 bitmap_clear(&inherit, start, nr);
5509 bitmap_clear(&always, start, nr);
5510 bitmap_clear(&within_size, start, nr);
5511 } else if (!strcmp(policy, "inherit")) {
5512 bitmap_set(&inherit, start, nr);
5513 bitmap_clear(&madvise, start, nr);
5514 bitmap_clear(&always, start, nr);
5515 bitmap_clear(&within_size, start, nr);
5516 } else if (!strcmp(policy, "within_size")) {
5517 bitmap_set(&within_size, start, nr);
5518 bitmap_clear(&inherit, start, nr);
5519 bitmap_clear(&madvise, start, nr);
5520 bitmap_clear(&always, start, nr);
5521 } else if (!strcmp(policy, "never")) {
5522 bitmap_clear(&inherit, start, nr);
5523 bitmap_clear(&madvise, start, nr);
5524 bitmap_clear(&always, start, nr);
5525 bitmap_clear(&within_size, start, nr);
5526 } else {
5527 pr_err("invalid policy %s in thp_shmem boot parameter\n", policy);
5528 goto err;
5529 }
5530 }
5531 }
5532
5533 huge_shmem_orders_always = always;
5534 huge_shmem_orders_madvise = madvise;
5535 huge_shmem_orders_inherit = inherit;
5536 huge_shmem_orders_within_size = within_size;
5537 shmem_orders_configured = true;
5538 return 1;
5539
5540err:
5541 pr_warn("thp_shmem=%s: error parsing string, ignoring setting\n", str);
5542 return 0;
5543}
5544__setup("thp_shmem=", setup_thp_shmem);
5545
5546#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
5547
5548#else /* !CONFIG_SHMEM */
5549
5550/*
5551 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
5552 *
5553 * This is intended for small system where the benefits of the full
5554 * shmem code (swap-backed and resource-limited) are outweighed by
5555 * their complexity. On systems without swap this code should be
5556 * effectively equivalent, but much lighter weight.
5557 */
5558
5559static struct file_system_type shmem_fs_type = {
5560 .name = "tmpfs",
5561 .init_fs_context = ramfs_init_fs_context,
5562 .parameters = ramfs_fs_parameters,
5563 .kill_sb = ramfs_kill_sb,
5564 .fs_flags = FS_USERNS_MOUNT,
5565};
5566
5567void __init shmem_init(void)
5568{
5569 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
5570
5571 shm_mnt = kern_mount(&shmem_fs_type);
5572 BUG_ON(IS_ERR(shm_mnt));
5573}
5574
5575int shmem_unuse(unsigned int type)
5576{
5577 return 0;
5578}
5579
5580int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
5581{
5582 return 0;
5583}
5584
5585void shmem_unlock_mapping(struct address_space *mapping)
5586{
5587}
5588
5589#ifdef CONFIG_MMU
5590unsigned long shmem_get_unmapped_area(struct file *file,
5591 unsigned long addr, unsigned long len,
5592 unsigned long pgoff, unsigned long flags)
5593{
5594 return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
5595}
5596#endif
5597
5598void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
5599{
5600 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
5601}
5602EXPORT_SYMBOL_GPL(shmem_truncate_range);
5603
5604#define shmem_vm_ops generic_file_vm_ops
5605#define shmem_anon_vm_ops generic_file_vm_ops
5606#define shmem_file_operations ramfs_file_operations
5607#define shmem_acct_size(flags, size) 0
5608#define shmem_unacct_size(flags, size) do {} while (0)
5609
5610static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
5611 struct super_block *sb, struct inode *dir,
5612 umode_t mode, dev_t dev, unsigned long flags)
5613{
5614 struct inode *inode = ramfs_get_inode(sb, dir, mode, dev);
5615 return inode ? inode : ERR_PTR(-ENOSPC);
5616}
5617
5618#endif /* CONFIG_SHMEM */
5619
5620/* common code */
5621
5622static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
5623 loff_t size, unsigned long flags, unsigned int i_flags)
5624{
5625 struct inode *inode;
5626 struct file *res;
5627
5628 if (IS_ERR(mnt))
5629 return ERR_CAST(mnt);
5630
5631 if (size < 0 || size > MAX_LFS_FILESIZE)
5632 return ERR_PTR(-EINVAL);
5633
5634 if (shmem_acct_size(flags, size))
5635 return ERR_PTR(-ENOMEM);
5636
5637 if (is_idmapped_mnt(mnt))
5638 return ERR_PTR(-EINVAL);
5639
5640 inode = shmem_get_inode(&nop_mnt_idmap, mnt->mnt_sb, NULL,
5641 S_IFREG | S_IRWXUGO, 0, flags);
5642 if (IS_ERR(inode)) {
5643 shmem_unacct_size(flags, size);
5644 return ERR_CAST(inode);
5645 }
5646 inode->i_flags |= i_flags;
5647 inode->i_size = size;
5648 clear_nlink(inode); /* It is unlinked */
5649 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
5650 if (!IS_ERR(res))
5651 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
5652 &shmem_file_operations);
5653 if (IS_ERR(res))
5654 iput(inode);
5655 return res;
5656}
5657
5658/**
5659 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
5660 * kernel internal. There will be NO LSM permission checks against the
5661 * underlying inode. So users of this interface must do LSM checks at a
5662 * higher layer. The users are the big_key and shm implementations. LSM
5663 * checks are provided at the key or shm level rather than the inode.
5664 * @name: name for dentry (to be seen in /proc/<pid>/maps
5665 * @size: size to be set for the file
5666 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
5667 */
5668struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
5669{
5670 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
5671}
5672EXPORT_SYMBOL_GPL(shmem_kernel_file_setup);
5673
5674/**
5675 * shmem_file_setup - get an unlinked file living in tmpfs
5676 * @name: name for dentry (to be seen in /proc/<pid>/maps
5677 * @size: size to be set for the file
5678 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
5679 */
5680struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
5681{
5682 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
5683}
5684EXPORT_SYMBOL_GPL(shmem_file_setup);
5685
5686/**
5687 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
5688 * @mnt: the tmpfs mount where the file will be created
5689 * @name: name for dentry (to be seen in /proc/<pid>/maps
5690 * @size: size to be set for the file
5691 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
5692 */
5693struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
5694 loff_t size, unsigned long flags)
5695{
5696 return __shmem_file_setup(mnt, name, size, flags, 0);
5697}
5698EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
5699
5700/**
5701 * shmem_zero_setup - setup a shared anonymous mapping
5702 * @vma: the vma to be mmapped is prepared by do_mmap
5703 */
5704int shmem_zero_setup(struct vm_area_struct *vma)
5705{
5706 struct file *file;
5707 loff_t size = vma->vm_end - vma->vm_start;
5708
5709 /*
5710 * Cloning a new file under mmap_lock leads to a lock ordering conflict
5711 * between XFS directory reading and selinux: since this file is only
5712 * accessible to the user through its mapping, use S_PRIVATE flag to
5713 * bypass file security, in the same way as shmem_kernel_file_setup().
5714 */
5715 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
5716 if (IS_ERR(file))
5717 return PTR_ERR(file);
5718
5719 if (vma->vm_file)
5720 fput(vma->vm_file);
5721 vma->vm_file = file;
5722 vma->vm_ops = &shmem_anon_vm_ops;
5723
5724 return 0;
5725}
5726
5727/**
5728 * shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
5729 * @mapping: the folio's address_space
5730 * @index: the folio index
5731 * @gfp: the page allocator flags to use if allocating
5732 *
5733 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
5734 * with any new page allocations done using the specified allocation flags.
5735 * But read_cache_page_gfp() uses the ->read_folio() method: which does not
5736 * suit tmpfs, since it may have pages in swapcache, and needs to find those
5737 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
5738 *
5739 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
5740 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
5741 */
5742struct folio *shmem_read_folio_gfp(struct address_space *mapping,
5743 pgoff_t index, gfp_t gfp)
5744{
5745#ifdef CONFIG_SHMEM
5746 struct inode *inode = mapping->host;
5747 struct folio *folio;
5748 int error;
5749
5750 error = shmem_get_folio_gfp(inode, index, 0, &folio, SGP_CACHE,
5751 gfp, NULL, NULL);
5752 if (error)
5753 return ERR_PTR(error);
5754
5755 folio_unlock(folio);
5756 return folio;
5757#else
5758 /*
5759 * The tiny !SHMEM case uses ramfs without swap
5760 */
5761 return mapping_read_folio_gfp(mapping, index, gfp);
5762#endif
5763}
5764EXPORT_SYMBOL_GPL(shmem_read_folio_gfp);
5765
5766struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
5767 pgoff_t index, gfp_t gfp)
5768{
5769 struct folio *folio = shmem_read_folio_gfp(mapping, index, gfp);
5770 struct page *page;
5771
5772 if (IS_ERR(folio))
5773 return &folio->page;
5774
5775 page = folio_file_page(folio, index);
5776 if (PageHWPoison(page)) {
5777 folio_put(folio);
5778 return ERR_PTR(-EIO);
5779 }
5780
5781 return page;
5782}
5783EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);