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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#include <asm/pgtable.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/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
96#define SHORT_SYMLINK_LEN 128
97
98/*
99 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
100 * inode->i_private (with i_mutex making sure that it has only one user at
101 * a time): we would prefer not to enlarge the shmem inode just for that.
102 */
103struct shmem_falloc {
104 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
105 pgoff_t start; /* start of range currently being fallocated */
106 pgoff_t next; /* the next page offset to be fallocated */
107 pgoff_t nr_falloced; /* how many new pages have been fallocated */
108 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
109};
110
111struct shmem_options {
112 unsigned long long blocks;
113 unsigned long long inodes;
114 struct mempolicy *mpol;
115 kuid_t uid;
116 kgid_t gid;
117 umode_t mode;
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};
124
125#ifdef CONFIG_TMPFS
126static unsigned long shmem_default_max_blocks(void)
127{
128 return totalram_pages() / 2;
129}
130
131static unsigned long shmem_default_max_inodes(void)
132{
133 unsigned long nr_pages = totalram_pages();
134
135 return min(nr_pages - totalhigh_pages(), nr_pages / 2);
136}
137#endif
138
139static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
140static int shmem_replace_page(struct page **pagep, gfp_t gfp,
141 struct shmem_inode_info *info, pgoff_t index);
142static int shmem_swapin_page(struct inode *inode, pgoff_t index,
143 struct page **pagep, enum sgp_type sgp,
144 gfp_t gfp, struct vm_area_struct *vma,
145 vm_fault_t *fault_type);
146static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
147 struct page **pagep, enum sgp_type sgp,
148 gfp_t gfp, struct vm_area_struct *vma,
149 struct vm_fault *vmf, vm_fault_t *fault_type);
150
151int shmem_getpage(struct inode *inode, pgoff_t index,
152 struct page **pagep, enum sgp_type sgp)
153{
154 return shmem_getpage_gfp(inode, index, pagep, sgp,
155 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
156}
157
158static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
159{
160 return sb->s_fs_info;
161}
162
163/*
164 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
165 * for shared memory and for shared anonymous (/dev/zero) mappings
166 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
167 * consistent with the pre-accounting of private mappings ...
168 */
169static inline int shmem_acct_size(unsigned long flags, loff_t size)
170{
171 return (flags & VM_NORESERVE) ?
172 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
173}
174
175static inline void shmem_unacct_size(unsigned long flags, loff_t size)
176{
177 if (!(flags & VM_NORESERVE))
178 vm_unacct_memory(VM_ACCT(size));
179}
180
181static inline int shmem_reacct_size(unsigned long flags,
182 loff_t oldsize, loff_t newsize)
183{
184 if (!(flags & VM_NORESERVE)) {
185 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
186 return security_vm_enough_memory_mm(current->mm,
187 VM_ACCT(newsize) - VM_ACCT(oldsize));
188 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
189 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
190 }
191 return 0;
192}
193
194/*
195 * ... whereas tmpfs objects are accounted incrementally as
196 * pages are allocated, in order to allow large sparse files.
197 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
198 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
199 */
200static inline int shmem_acct_block(unsigned long flags, long pages)
201{
202 if (!(flags & VM_NORESERVE))
203 return 0;
204
205 return security_vm_enough_memory_mm(current->mm,
206 pages * VM_ACCT(PAGE_SIZE));
207}
208
209static inline void shmem_unacct_blocks(unsigned long flags, long pages)
210{
211 if (flags & VM_NORESERVE)
212 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
213}
214
215static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
216{
217 struct shmem_inode_info *info = SHMEM_I(inode);
218 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
219
220 if (shmem_acct_block(info->flags, pages))
221 return false;
222
223 if (sbinfo->max_blocks) {
224 if (percpu_counter_compare(&sbinfo->used_blocks,
225 sbinfo->max_blocks - pages) > 0)
226 goto unacct;
227 percpu_counter_add(&sbinfo->used_blocks, pages);
228 }
229
230 return true;
231
232unacct:
233 shmem_unacct_blocks(info->flags, pages);
234 return false;
235}
236
237static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
238{
239 struct shmem_inode_info *info = SHMEM_I(inode);
240 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
241
242 if (sbinfo->max_blocks)
243 percpu_counter_sub(&sbinfo->used_blocks, pages);
244 shmem_unacct_blocks(info->flags, pages);
245}
246
247static const struct super_operations shmem_ops;
248static const struct address_space_operations shmem_aops;
249static const struct file_operations shmem_file_operations;
250static const struct inode_operations shmem_inode_operations;
251static const struct inode_operations shmem_dir_inode_operations;
252static const struct inode_operations shmem_special_inode_operations;
253static const struct vm_operations_struct shmem_vm_ops;
254static struct file_system_type shmem_fs_type;
255
256bool vma_is_shmem(struct vm_area_struct *vma)
257{
258 return vma->vm_ops == &shmem_vm_ops;
259}
260
261static LIST_HEAD(shmem_swaplist);
262static DEFINE_MUTEX(shmem_swaplist_mutex);
263
264static int shmem_reserve_inode(struct super_block *sb)
265{
266 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
267 if (sbinfo->max_inodes) {
268 spin_lock(&sbinfo->stat_lock);
269 if (!sbinfo->free_inodes) {
270 spin_unlock(&sbinfo->stat_lock);
271 return -ENOSPC;
272 }
273 sbinfo->free_inodes--;
274 spin_unlock(&sbinfo->stat_lock);
275 }
276 return 0;
277}
278
279static void shmem_free_inode(struct super_block *sb)
280{
281 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
282 if (sbinfo->max_inodes) {
283 spin_lock(&sbinfo->stat_lock);
284 sbinfo->free_inodes++;
285 spin_unlock(&sbinfo->stat_lock);
286 }
287}
288
289/**
290 * shmem_recalc_inode - recalculate the block usage of an inode
291 * @inode: inode to recalc
292 *
293 * We have to calculate the free blocks since the mm can drop
294 * undirtied hole pages behind our back.
295 *
296 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
297 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
298 *
299 * It has to be called with the spinlock held.
300 */
301static void shmem_recalc_inode(struct inode *inode)
302{
303 struct shmem_inode_info *info = SHMEM_I(inode);
304 long freed;
305
306 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
307 if (freed > 0) {
308 info->alloced -= freed;
309 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
310 shmem_inode_unacct_blocks(inode, freed);
311 }
312}
313
314bool shmem_charge(struct inode *inode, long pages)
315{
316 struct shmem_inode_info *info = SHMEM_I(inode);
317 unsigned long flags;
318
319 if (!shmem_inode_acct_block(inode, pages))
320 return false;
321
322 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
323 inode->i_mapping->nrpages += pages;
324
325 spin_lock_irqsave(&info->lock, flags);
326 info->alloced += pages;
327 inode->i_blocks += pages * BLOCKS_PER_PAGE;
328 shmem_recalc_inode(inode);
329 spin_unlock_irqrestore(&info->lock, flags);
330
331 return true;
332}
333
334void shmem_uncharge(struct inode *inode, long pages)
335{
336 struct shmem_inode_info *info = SHMEM_I(inode);
337 unsigned long flags;
338
339 /* nrpages adjustment done by __delete_from_page_cache() or caller */
340
341 spin_lock_irqsave(&info->lock, flags);
342 info->alloced -= pages;
343 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
344 shmem_recalc_inode(inode);
345 spin_unlock_irqrestore(&info->lock, flags);
346
347 shmem_inode_unacct_blocks(inode, pages);
348}
349
350/*
351 * Replace item expected in xarray by a new item, while holding xa_lock.
352 */
353static int shmem_replace_entry(struct address_space *mapping,
354 pgoff_t index, void *expected, void *replacement)
355{
356 XA_STATE(xas, &mapping->i_pages, index);
357 void *item;
358
359 VM_BUG_ON(!expected);
360 VM_BUG_ON(!replacement);
361 item = xas_load(&xas);
362 if (item != expected)
363 return -ENOENT;
364 xas_store(&xas, replacement);
365 return 0;
366}
367
368/*
369 * Sometimes, before we decide whether to proceed or to fail, we must check
370 * that an entry was not already brought back from swap by a racing thread.
371 *
372 * Checking page is not enough: by the time a SwapCache page is locked, it
373 * might be reused, and again be SwapCache, using the same swap as before.
374 */
375static bool shmem_confirm_swap(struct address_space *mapping,
376 pgoff_t index, swp_entry_t swap)
377{
378 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
379}
380
381/*
382 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
383 *
384 * SHMEM_HUGE_NEVER:
385 * disables huge pages for the mount;
386 * SHMEM_HUGE_ALWAYS:
387 * enables huge pages for the mount;
388 * SHMEM_HUGE_WITHIN_SIZE:
389 * only allocate huge pages if the page will be fully within i_size,
390 * also respect fadvise()/madvise() hints;
391 * SHMEM_HUGE_ADVISE:
392 * only allocate huge pages if requested with fadvise()/madvise();
393 */
394
395#define SHMEM_HUGE_NEVER 0
396#define SHMEM_HUGE_ALWAYS 1
397#define SHMEM_HUGE_WITHIN_SIZE 2
398#define SHMEM_HUGE_ADVISE 3
399
400/*
401 * Special values.
402 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
403 *
404 * SHMEM_HUGE_DENY:
405 * disables huge on shm_mnt and all mounts, for emergency use;
406 * SHMEM_HUGE_FORCE:
407 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
408 *
409 */
410#define SHMEM_HUGE_DENY (-1)
411#define SHMEM_HUGE_FORCE (-2)
412
413#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
414/* ifdef here to avoid bloating shmem.o when not necessary */
415
416static int shmem_huge __read_mostly;
417
418#if defined(CONFIG_SYSFS)
419static int shmem_parse_huge(const char *str)
420{
421 if (!strcmp(str, "never"))
422 return SHMEM_HUGE_NEVER;
423 if (!strcmp(str, "always"))
424 return SHMEM_HUGE_ALWAYS;
425 if (!strcmp(str, "within_size"))
426 return SHMEM_HUGE_WITHIN_SIZE;
427 if (!strcmp(str, "advise"))
428 return SHMEM_HUGE_ADVISE;
429 if (!strcmp(str, "deny"))
430 return SHMEM_HUGE_DENY;
431 if (!strcmp(str, "force"))
432 return SHMEM_HUGE_FORCE;
433 return -EINVAL;
434}
435#endif
436
437#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
438static const char *shmem_format_huge(int huge)
439{
440 switch (huge) {
441 case SHMEM_HUGE_NEVER:
442 return "never";
443 case SHMEM_HUGE_ALWAYS:
444 return "always";
445 case SHMEM_HUGE_WITHIN_SIZE:
446 return "within_size";
447 case SHMEM_HUGE_ADVISE:
448 return "advise";
449 case SHMEM_HUGE_DENY:
450 return "deny";
451 case SHMEM_HUGE_FORCE:
452 return "force";
453 default:
454 VM_BUG_ON(1);
455 return "bad_val";
456 }
457}
458#endif
459
460static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
461 struct shrink_control *sc, unsigned long nr_to_split)
462{
463 LIST_HEAD(list), *pos, *next;
464 LIST_HEAD(to_remove);
465 struct inode *inode;
466 struct shmem_inode_info *info;
467 struct page *page;
468 unsigned long batch = sc ? sc->nr_to_scan : 128;
469 int removed = 0, split = 0;
470
471 if (list_empty(&sbinfo->shrinklist))
472 return SHRINK_STOP;
473
474 spin_lock(&sbinfo->shrinklist_lock);
475 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
476 info = list_entry(pos, struct shmem_inode_info, shrinklist);
477
478 /* pin the inode */
479 inode = igrab(&info->vfs_inode);
480
481 /* inode is about to be evicted */
482 if (!inode) {
483 list_del_init(&info->shrinklist);
484 removed++;
485 goto next;
486 }
487
488 /* Check if there's anything to gain */
489 if (round_up(inode->i_size, PAGE_SIZE) ==
490 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
491 list_move(&info->shrinklist, &to_remove);
492 removed++;
493 goto next;
494 }
495
496 list_move(&info->shrinklist, &list);
497next:
498 if (!--batch)
499 break;
500 }
501 spin_unlock(&sbinfo->shrinklist_lock);
502
503 list_for_each_safe(pos, next, &to_remove) {
504 info = list_entry(pos, struct shmem_inode_info, shrinklist);
505 inode = &info->vfs_inode;
506 list_del_init(&info->shrinklist);
507 iput(inode);
508 }
509
510 list_for_each_safe(pos, next, &list) {
511 int ret;
512
513 info = list_entry(pos, struct shmem_inode_info, shrinklist);
514 inode = &info->vfs_inode;
515
516 if (nr_to_split && split >= nr_to_split)
517 goto leave;
518
519 page = find_get_page(inode->i_mapping,
520 (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
521 if (!page)
522 goto drop;
523
524 /* No huge page at the end of the file: nothing to split */
525 if (!PageTransHuge(page)) {
526 put_page(page);
527 goto drop;
528 }
529
530 /*
531 * Leave the inode on the list if we failed to lock
532 * the page at this time.
533 *
534 * Waiting for the lock may lead to deadlock in the
535 * reclaim path.
536 */
537 if (!trylock_page(page)) {
538 put_page(page);
539 goto leave;
540 }
541
542 ret = split_huge_page(page);
543 unlock_page(page);
544 put_page(page);
545
546 /* If split failed leave the inode on the list */
547 if (ret)
548 goto leave;
549
550 split++;
551drop:
552 list_del_init(&info->shrinklist);
553 removed++;
554leave:
555 iput(inode);
556 }
557
558 spin_lock(&sbinfo->shrinklist_lock);
559 list_splice_tail(&list, &sbinfo->shrinklist);
560 sbinfo->shrinklist_len -= removed;
561 spin_unlock(&sbinfo->shrinklist_lock);
562
563 return split;
564}
565
566static long shmem_unused_huge_scan(struct super_block *sb,
567 struct shrink_control *sc)
568{
569 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
570
571 if (!READ_ONCE(sbinfo->shrinklist_len))
572 return SHRINK_STOP;
573
574 return shmem_unused_huge_shrink(sbinfo, sc, 0);
575}
576
577static long shmem_unused_huge_count(struct super_block *sb,
578 struct shrink_control *sc)
579{
580 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
581 return READ_ONCE(sbinfo->shrinklist_len);
582}
583#else /* !CONFIG_TRANSPARENT_HUGE_PAGECACHE */
584
585#define shmem_huge SHMEM_HUGE_DENY
586
587static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
588 struct shrink_control *sc, unsigned long nr_to_split)
589{
590 return 0;
591}
592#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
593
594static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo)
595{
596 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
597 (shmem_huge == SHMEM_HUGE_FORCE || sbinfo->huge) &&
598 shmem_huge != SHMEM_HUGE_DENY)
599 return true;
600 return false;
601}
602
603/*
604 * Like add_to_page_cache_locked, but error if expected item has gone.
605 */
606static int shmem_add_to_page_cache(struct page *page,
607 struct address_space *mapping,
608 pgoff_t index, void *expected, gfp_t gfp)
609{
610 XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
611 unsigned long i = 0;
612 unsigned long nr = compound_nr(page);
613
614 VM_BUG_ON_PAGE(PageTail(page), page);
615 VM_BUG_ON_PAGE(index != round_down(index, nr), page);
616 VM_BUG_ON_PAGE(!PageLocked(page), page);
617 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
618 VM_BUG_ON(expected && PageTransHuge(page));
619
620 page_ref_add(page, nr);
621 page->mapping = mapping;
622 page->index = index;
623
624 do {
625 void *entry;
626 xas_lock_irq(&xas);
627 entry = xas_find_conflict(&xas);
628 if (entry != expected)
629 xas_set_err(&xas, -EEXIST);
630 xas_create_range(&xas);
631 if (xas_error(&xas))
632 goto unlock;
633next:
634 xas_store(&xas, page);
635 if (++i < nr) {
636 xas_next(&xas);
637 goto next;
638 }
639 if (PageTransHuge(page)) {
640 count_vm_event(THP_FILE_ALLOC);
641 __inc_node_page_state(page, NR_SHMEM_THPS);
642 }
643 mapping->nrpages += nr;
644 __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
645 __mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
646unlock:
647 xas_unlock_irq(&xas);
648 } while (xas_nomem(&xas, gfp));
649
650 if (xas_error(&xas)) {
651 page->mapping = NULL;
652 page_ref_sub(page, nr);
653 return xas_error(&xas);
654 }
655
656 return 0;
657}
658
659/*
660 * Like delete_from_page_cache, but substitutes swap for page.
661 */
662static void shmem_delete_from_page_cache(struct page *page, void *radswap)
663{
664 struct address_space *mapping = page->mapping;
665 int error;
666
667 VM_BUG_ON_PAGE(PageCompound(page), page);
668
669 xa_lock_irq(&mapping->i_pages);
670 error = shmem_replace_entry(mapping, page->index, page, radswap);
671 page->mapping = NULL;
672 mapping->nrpages--;
673 __dec_node_page_state(page, NR_FILE_PAGES);
674 __dec_node_page_state(page, NR_SHMEM);
675 xa_unlock_irq(&mapping->i_pages);
676 put_page(page);
677 BUG_ON(error);
678}
679
680/*
681 * Remove swap entry from page cache, free the swap and its page cache.
682 */
683static int shmem_free_swap(struct address_space *mapping,
684 pgoff_t index, void *radswap)
685{
686 void *old;
687
688 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
689 if (old != radswap)
690 return -ENOENT;
691 free_swap_and_cache(radix_to_swp_entry(radswap));
692 return 0;
693}
694
695/*
696 * Determine (in bytes) how many of the shmem object's pages mapped by the
697 * given offsets are swapped out.
698 *
699 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
700 * as long as the inode doesn't go away and racy results are not a problem.
701 */
702unsigned long shmem_partial_swap_usage(struct address_space *mapping,
703 pgoff_t start, pgoff_t end)
704{
705 XA_STATE(xas, &mapping->i_pages, start);
706 struct page *page;
707 unsigned long swapped = 0;
708
709 rcu_read_lock();
710 xas_for_each(&xas, page, end - 1) {
711 if (xas_retry(&xas, page))
712 continue;
713 if (xa_is_value(page))
714 swapped++;
715
716 if (need_resched()) {
717 xas_pause(&xas);
718 cond_resched_rcu();
719 }
720 }
721
722 rcu_read_unlock();
723
724 return swapped << PAGE_SHIFT;
725}
726
727/*
728 * Determine (in bytes) how many of the shmem object's pages mapped by the
729 * given vma is swapped out.
730 *
731 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
732 * as long as the inode doesn't go away and racy results are not a problem.
733 */
734unsigned long shmem_swap_usage(struct vm_area_struct *vma)
735{
736 struct inode *inode = file_inode(vma->vm_file);
737 struct shmem_inode_info *info = SHMEM_I(inode);
738 struct address_space *mapping = inode->i_mapping;
739 unsigned long swapped;
740
741 /* Be careful as we don't hold info->lock */
742 swapped = READ_ONCE(info->swapped);
743
744 /*
745 * The easier cases are when the shmem object has nothing in swap, or
746 * the vma maps it whole. Then we can simply use the stats that we
747 * already track.
748 */
749 if (!swapped)
750 return 0;
751
752 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
753 return swapped << PAGE_SHIFT;
754
755 /* Here comes the more involved part */
756 return shmem_partial_swap_usage(mapping,
757 linear_page_index(vma, vma->vm_start),
758 linear_page_index(vma, vma->vm_end));
759}
760
761/*
762 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
763 */
764void shmem_unlock_mapping(struct address_space *mapping)
765{
766 struct pagevec pvec;
767 pgoff_t indices[PAGEVEC_SIZE];
768 pgoff_t index = 0;
769
770 pagevec_init(&pvec);
771 /*
772 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
773 */
774 while (!mapping_unevictable(mapping)) {
775 /*
776 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
777 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
778 */
779 pvec.nr = find_get_entries(mapping, index,
780 PAGEVEC_SIZE, pvec.pages, indices);
781 if (!pvec.nr)
782 break;
783 index = indices[pvec.nr - 1] + 1;
784 pagevec_remove_exceptionals(&pvec);
785 check_move_unevictable_pages(&pvec);
786 pagevec_release(&pvec);
787 cond_resched();
788 }
789}
790
791/*
792 * Remove range of pages and swap entries from page cache, and free them.
793 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
794 */
795static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
796 bool unfalloc)
797{
798 struct address_space *mapping = inode->i_mapping;
799 struct shmem_inode_info *info = SHMEM_I(inode);
800 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
801 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
802 unsigned int partial_start = lstart & (PAGE_SIZE - 1);
803 unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
804 struct pagevec pvec;
805 pgoff_t indices[PAGEVEC_SIZE];
806 long nr_swaps_freed = 0;
807 pgoff_t index;
808 int i;
809
810 if (lend == -1)
811 end = -1; /* unsigned, so actually very big */
812
813 pagevec_init(&pvec);
814 index = start;
815 while (index < end) {
816 pvec.nr = find_get_entries(mapping, index,
817 min(end - index, (pgoff_t)PAGEVEC_SIZE),
818 pvec.pages, indices);
819 if (!pvec.nr)
820 break;
821 for (i = 0; i < pagevec_count(&pvec); i++) {
822 struct page *page = pvec.pages[i];
823
824 index = indices[i];
825 if (index >= end)
826 break;
827
828 if (xa_is_value(page)) {
829 if (unfalloc)
830 continue;
831 nr_swaps_freed += !shmem_free_swap(mapping,
832 index, page);
833 continue;
834 }
835
836 VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
837
838 if (!trylock_page(page))
839 continue;
840
841 if (PageTransTail(page)) {
842 /* Middle of THP: zero out the page */
843 clear_highpage(page);
844 unlock_page(page);
845 continue;
846 } else if (PageTransHuge(page)) {
847 if (index == round_down(end, HPAGE_PMD_NR)) {
848 /*
849 * Range ends in the middle of THP:
850 * zero out the page
851 */
852 clear_highpage(page);
853 unlock_page(page);
854 continue;
855 }
856 index += HPAGE_PMD_NR - 1;
857 i += HPAGE_PMD_NR - 1;
858 }
859
860 if (!unfalloc || !PageUptodate(page)) {
861 VM_BUG_ON_PAGE(PageTail(page), page);
862 if (page_mapping(page) == mapping) {
863 VM_BUG_ON_PAGE(PageWriteback(page), page);
864 truncate_inode_page(mapping, page);
865 }
866 }
867 unlock_page(page);
868 }
869 pagevec_remove_exceptionals(&pvec);
870 pagevec_release(&pvec);
871 cond_resched();
872 index++;
873 }
874
875 if (partial_start) {
876 struct page *page = NULL;
877 shmem_getpage(inode, start - 1, &page, SGP_READ);
878 if (page) {
879 unsigned int top = PAGE_SIZE;
880 if (start > end) {
881 top = partial_end;
882 partial_end = 0;
883 }
884 zero_user_segment(page, partial_start, top);
885 set_page_dirty(page);
886 unlock_page(page);
887 put_page(page);
888 }
889 }
890 if (partial_end) {
891 struct page *page = NULL;
892 shmem_getpage(inode, end, &page, SGP_READ);
893 if (page) {
894 zero_user_segment(page, 0, partial_end);
895 set_page_dirty(page);
896 unlock_page(page);
897 put_page(page);
898 }
899 }
900 if (start >= end)
901 return;
902
903 index = start;
904 while (index < end) {
905 cond_resched();
906
907 pvec.nr = find_get_entries(mapping, index,
908 min(end - index, (pgoff_t)PAGEVEC_SIZE),
909 pvec.pages, indices);
910 if (!pvec.nr) {
911 /* If all gone or hole-punch or unfalloc, we're done */
912 if (index == start || end != -1)
913 break;
914 /* But if truncating, restart to make sure all gone */
915 index = start;
916 continue;
917 }
918 for (i = 0; i < pagevec_count(&pvec); i++) {
919 struct page *page = pvec.pages[i];
920
921 index = indices[i];
922 if (index >= end)
923 break;
924
925 if (xa_is_value(page)) {
926 if (unfalloc)
927 continue;
928 if (shmem_free_swap(mapping, index, page)) {
929 /* Swap was replaced by page: retry */
930 index--;
931 break;
932 }
933 nr_swaps_freed++;
934 continue;
935 }
936
937 lock_page(page);
938
939 if (PageTransTail(page)) {
940 /* Middle of THP: zero out the page */
941 clear_highpage(page);
942 unlock_page(page);
943 /*
944 * Partial thp truncate due 'start' in middle
945 * of THP: don't need to look on these pages
946 * again on !pvec.nr restart.
947 */
948 if (index != round_down(end, HPAGE_PMD_NR))
949 start++;
950 continue;
951 } else if (PageTransHuge(page)) {
952 if (index == round_down(end, HPAGE_PMD_NR)) {
953 /*
954 * Range ends in the middle of THP:
955 * zero out the page
956 */
957 clear_highpage(page);
958 unlock_page(page);
959 continue;
960 }
961 index += HPAGE_PMD_NR - 1;
962 i += HPAGE_PMD_NR - 1;
963 }
964
965 if (!unfalloc || !PageUptodate(page)) {
966 VM_BUG_ON_PAGE(PageTail(page), page);
967 if (page_mapping(page) == mapping) {
968 VM_BUG_ON_PAGE(PageWriteback(page), page);
969 truncate_inode_page(mapping, page);
970 } else {
971 /* Page was replaced by swap: retry */
972 unlock_page(page);
973 index--;
974 break;
975 }
976 }
977 unlock_page(page);
978 }
979 pagevec_remove_exceptionals(&pvec);
980 pagevec_release(&pvec);
981 index++;
982 }
983
984 spin_lock_irq(&info->lock);
985 info->swapped -= nr_swaps_freed;
986 shmem_recalc_inode(inode);
987 spin_unlock_irq(&info->lock);
988}
989
990void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
991{
992 shmem_undo_range(inode, lstart, lend, false);
993 inode->i_ctime = inode->i_mtime = current_time(inode);
994}
995EXPORT_SYMBOL_GPL(shmem_truncate_range);
996
997static int shmem_getattr(const struct path *path, struct kstat *stat,
998 u32 request_mask, unsigned int query_flags)
999{
1000 struct inode *inode = path->dentry->d_inode;
1001 struct shmem_inode_info *info = SHMEM_I(inode);
1002 struct shmem_sb_info *sb_info = SHMEM_SB(inode->i_sb);
1003
1004 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
1005 spin_lock_irq(&info->lock);
1006 shmem_recalc_inode(inode);
1007 spin_unlock_irq(&info->lock);
1008 }
1009 generic_fillattr(inode, stat);
1010
1011 if (is_huge_enabled(sb_info))
1012 stat->blksize = HPAGE_PMD_SIZE;
1013
1014 return 0;
1015}
1016
1017static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
1018{
1019 struct inode *inode = d_inode(dentry);
1020 struct shmem_inode_info *info = SHMEM_I(inode);
1021 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1022 int error;
1023
1024 error = setattr_prepare(dentry, attr);
1025 if (error)
1026 return error;
1027
1028 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1029 loff_t oldsize = inode->i_size;
1030 loff_t newsize = attr->ia_size;
1031
1032 /* protected by i_mutex */
1033 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1034 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1035 return -EPERM;
1036
1037 if (newsize != oldsize) {
1038 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1039 oldsize, newsize);
1040 if (error)
1041 return error;
1042 i_size_write(inode, newsize);
1043 inode->i_ctime = inode->i_mtime = current_time(inode);
1044 }
1045 if (newsize <= oldsize) {
1046 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1047 if (oldsize > holebegin)
1048 unmap_mapping_range(inode->i_mapping,
1049 holebegin, 0, 1);
1050 if (info->alloced)
1051 shmem_truncate_range(inode,
1052 newsize, (loff_t)-1);
1053 /* unmap again to remove racily COWed private pages */
1054 if (oldsize > holebegin)
1055 unmap_mapping_range(inode->i_mapping,
1056 holebegin, 0, 1);
1057
1058 /*
1059 * Part of the huge page can be beyond i_size: subject
1060 * to shrink under memory pressure.
1061 */
1062 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
1063 spin_lock(&sbinfo->shrinklist_lock);
1064 /*
1065 * _careful to defend against unlocked access to
1066 * ->shrink_list in shmem_unused_huge_shrink()
1067 */
1068 if (list_empty_careful(&info->shrinklist)) {
1069 list_add_tail(&info->shrinklist,
1070 &sbinfo->shrinklist);
1071 sbinfo->shrinklist_len++;
1072 }
1073 spin_unlock(&sbinfo->shrinklist_lock);
1074 }
1075 }
1076 }
1077
1078 setattr_copy(inode, attr);
1079 if (attr->ia_valid & ATTR_MODE)
1080 error = posix_acl_chmod(inode, inode->i_mode);
1081 return error;
1082}
1083
1084static void shmem_evict_inode(struct inode *inode)
1085{
1086 struct shmem_inode_info *info = SHMEM_I(inode);
1087 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1088
1089 if (inode->i_mapping->a_ops == &shmem_aops) {
1090 shmem_unacct_size(info->flags, inode->i_size);
1091 inode->i_size = 0;
1092 shmem_truncate_range(inode, 0, (loff_t)-1);
1093 if (!list_empty(&info->shrinklist)) {
1094 spin_lock(&sbinfo->shrinklist_lock);
1095 if (!list_empty(&info->shrinklist)) {
1096 list_del_init(&info->shrinklist);
1097 sbinfo->shrinklist_len--;
1098 }
1099 spin_unlock(&sbinfo->shrinklist_lock);
1100 }
1101 while (!list_empty(&info->swaplist)) {
1102 /* Wait while shmem_unuse() is scanning this inode... */
1103 wait_var_event(&info->stop_eviction,
1104 !atomic_read(&info->stop_eviction));
1105 mutex_lock(&shmem_swaplist_mutex);
1106 /* ...but beware of the race if we peeked too early */
1107 if (!atomic_read(&info->stop_eviction))
1108 list_del_init(&info->swaplist);
1109 mutex_unlock(&shmem_swaplist_mutex);
1110 }
1111 }
1112
1113 simple_xattrs_free(&info->xattrs);
1114 WARN_ON(inode->i_blocks);
1115 shmem_free_inode(inode->i_sb);
1116 clear_inode(inode);
1117}
1118
1119extern struct swap_info_struct *swap_info[];
1120
1121static int shmem_find_swap_entries(struct address_space *mapping,
1122 pgoff_t start, unsigned int nr_entries,
1123 struct page **entries, pgoff_t *indices,
1124 unsigned int type, bool frontswap)
1125{
1126 XA_STATE(xas, &mapping->i_pages, start);
1127 struct page *page;
1128 swp_entry_t entry;
1129 unsigned int ret = 0;
1130
1131 if (!nr_entries)
1132 return 0;
1133
1134 rcu_read_lock();
1135 xas_for_each(&xas, page, ULONG_MAX) {
1136 if (xas_retry(&xas, page))
1137 continue;
1138
1139 if (!xa_is_value(page))
1140 continue;
1141
1142 entry = radix_to_swp_entry(page);
1143 if (swp_type(entry) != type)
1144 continue;
1145 if (frontswap &&
1146 !frontswap_test(swap_info[type], swp_offset(entry)))
1147 continue;
1148
1149 indices[ret] = xas.xa_index;
1150 entries[ret] = page;
1151
1152 if (need_resched()) {
1153 xas_pause(&xas);
1154 cond_resched_rcu();
1155 }
1156 if (++ret == nr_entries)
1157 break;
1158 }
1159 rcu_read_unlock();
1160
1161 return ret;
1162}
1163
1164/*
1165 * Move the swapped pages for an inode to page cache. Returns the count
1166 * of pages swapped in, or the error in case of failure.
1167 */
1168static int shmem_unuse_swap_entries(struct inode *inode, struct pagevec pvec,
1169 pgoff_t *indices)
1170{
1171 int i = 0;
1172 int ret = 0;
1173 int error = 0;
1174 struct address_space *mapping = inode->i_mapping;
1175
1176 for (i = 0; i < pvec.nr; i++) {
1177 struct page *page = pvec.pages[i];
1178
1179 if (!xa_is_value(page))
1180 continue;
1181 error = shmem_swapin_page(inode, indices[i],
1182 &page, SGP_CACHE,
1183 mapping_gfp_mask(mapping),
1184 NULL, NULL);
1185 if (error == 0) {
1186 unlock_page(page);
1187 put_page(page);
1188 ret++;
1189 }
1190 if (error == -ENOMEM)
1191 break;
1192 error = 0;
1193 }
1194 return error ? error : ret;
1195}
1196
1197/*
1198 * If swap found in inode, free it and move page from swapcache to filecache.
1199 */
1200static int shmem_unuse_inode(struct inode *inode, unsigned int type,
1201 bool frontswap, unsigned long *fs_pages_to_unuse)
1202{
1203 struct address_space *mapping = inode->i_mapping;
1204 pgoff_t start = 0;
1205 struct pagevec pvec;
1206 pgoff_t indices[PAGEVEC_SIZE];
1207 bool frontswap_partial = (frontswap && *fs_pages_to_unuse > 0);
1208 int ret = 0;
1209
1210 pagevec_init(&pvec);
1211 do {
1212 unsigned int nr_entries = PAGEVEC_SIZE;
1213
1214 if (frontswap_partial && *fs_pages_to_unuse < PAGEVEC_SIZE)
1215 nr_entries = *fs_pages_to_unuse;
1216
1217 pvec.nr = shmem_find_swap_entries(mapping, start, nr_entries,
1218 pvec.pages, indices,
1219 type, frontswap);
1220 if (pvec.nr == 0) {
1221 ret = 0;
1222 break;
1223 }
1224
1225 ret = shmem_unuse_swap_entries(inode, pvec, indices);
1226 if (ret < 0)
1227 break;
1228
1229 if (frontswap_partial) {
1230 *fs_pages_to_unuse -= ret;
1231 if (*fs_pages_to_unuse == 0) {
1232 ret = FRONTSWAP_PAGES_UNUSED;
1233 break;
1234 }
1235 }
1236
1237 start = indices[pvec.nr - 1];
1238 } while (true);
1239
1240 return ret;
1241}
1242
1243/*
1244 * Read all the shared memory data that resides in the swap
1245 * device 'type' back into memory, so the swap device can be
1246 * unused.
1247 */
1248int shmem_unuse(unsigned int type, bool frontswap,
1249 unsigned long *fs_pages_to_unuse)
1250{
1251 struct shmem_inode_info *info, *next;
1252 int error = 0;
1253
1254 if (list_empty(&shmem_swaplist))
1255 return 0;
1256
1257 mutex_lock(&shmem_swaplist_mutex);
1258 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1259 if (!info->swapped) {
1260 list_del_init(&info->swaplist);
1261 continue;
1262 }
1263 /*
1264 * Drop the swaplist mutex while searching the inode for swap;
1265 * but before doing so, make sure shmem_evict_inode() will not
1266 * remove placeholder inode from swaplist, nor let it be freed
1267 * (igrab() would protect from unlink, but not from unmount).
1268 */
1269 atomic_inc(&info->stop_eviction);
1270 mutex_unlock(&shmem_swaplist_mutex);
1271
1272 error = shmem_unuse_inode(&info->vfs_inode, type, frontswap,
1273 fs_pages_to_unuse);
1274 cond_resched();
1275
1276 mutex_lock(&shmem_swaplist_mutex);
1277 next = list_next_entry(info, swaplist);
1278 if (!info->swapped)
1279 list_del_init(&info->swaplist);
1280 if (atomic_dec_and_test(&info->stop_eviction))
1281 wake_up_var(&info->stop_eviction);
1282 if (error)
1283 break;
1284 }
1285 mutex_unlock(&shmem_swaplist_mutex);
1286
1287 return error;
1288}
1289
1290/*
1291 * Move the page from the page cache to the swap cache.
1292 */
1293static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1294{
1295 struct shmem_inode_info *info;
1296 struct address_space *mapping;
1297 struct inode *inode;
1298 swp_entry_t swap;
1299 pgoff_t index;
1300
1301 VM_BUG_ON_PAGE(PageCompound(page), page);
1302 BUG_ON(!PageLocked(page));
1303 mapping = page->mapping;
1304 index = page->index;
1305 inode = mapping->host;
1306 info = SHMEM_I(inode);
1307 if (info->flags & VM_LOCKED)
1308 goto redirty;
1309 if (!total_swap_pages)
1310 goto redirty;
1311
1312 /*
1313 * Our capabilities prevent regular writeback or sync from ever calling
1314 * shmem_writepage; but a stacking filesystem might use ->writepage of
1315 * its underlying filesystem, in which case tmpfs should write out to
1316 * swap only in response to memory pressure, and not for the writeback
1317 * threads or sync.
1318 */
1319 if (!wbc->for_reclaim) {
1320 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1321 goto redirty;
1322 }
1323
1324 /*
1325 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1326 * value into swapfile.c, the only way we can correctly account for a
1327 * fallocated page arriving here is now to initialize it and write it.
1328 *
1329 * That's okay for a page already fallocated earlier, but if we have
1330 * not yet completed the fallocation, then (a) we want to keep track
1331 * of this page in case we have to undo it, and (b) it may not be a
1332 * good idea to continue anyway, once we're pushing into swap. So
1333 * reactivate the page, and let shmem_fallocate() quit when too many.
1334 */
1335 if (!PageUptodate(page)) {
1336 if (inode->i_private) {
1337 struct shmem_falloc *shmem_falloc;
1338 spin_lock(&inode->i_lock);
1339 shmem_falloc = inode->i_private;
1340 if (shmem_falloc &&
1341 !shmem_falloc->waitq &&
1342 index >= shmem_falloc->start &&
1343 index < shmem_falloc->next)
1344 shmem_falloc->nr_unswapped++;
1345 else
1346 shmem_falloc = NULL;
1347 spin_unlock(&inode->i_lock);
1348 if (shmem_falloc)
1349 goto redirty;
1350 }
1351 clear_highpage(page);
1352 flush_dcache_page(page);
1353 SetPageUptodate(page);
1354 }
1355
1356 swap = get_swap_page(page);
1357 if (!swap.val)
1358 goto redirty;
1359
1360 /*
1361 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1362 * if it's not already there. Do it now before the page is
1363 * moved to swap cache, when its pagelock no longer protects
1364 * the inode from eviction. But don't unlock the mutex until
1365 * we've incremented swapped, because shmem_unuse_inode() will
1366 * prune a !swapped inode from the swaplist under this mutex.
1367 */
1368 mutex_lock(&shmem_swaplist_mutex);
1369 if (list_empty(&info->swaplist))
1370 list_add(&info->swaplist, &shmem_swaplist);
1371
1372 if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1373 spin_lock_irq(&info->lock);
1374 shmem_recalc_inode(inode);
1375 info->swapped++;
1376 spin_unlock_irq(&info->lock);
1377
1378 swap_shmem_alloc(swap);
1379 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1380
1381 mutex_unlock(&shmem_swaplist_mutex);
1382 BUG_ON(page_mapped(page));
1383 swap_writepage(page, wbc);
1384 return 0;
1385 }
1386
1387 mutex_unlock(&shmem_swaplist_mutex);
1388 put_swap_page(page, swap);
1389redirty:
1390 set_page_dirty(page);
1391 if (wbc->for_reclaim)
1392 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1393 unlock_page(page);
1394 return 0;
1395}
1396
1397#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1398static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1399{
1400 char buffer[64];
1401
1402 if (!mpol || mpol->mode == MPOL_DEFAULT)
1403 return; /* show nothing */
1404
1405 mpol_to_str(buffer, sizeof(buffer), mpol);
1406
1407 seq_printf(seq, ",mpol=%s", buffer);
1408}
1409
1410static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1411{
1412 struct mempolicy *mpol = NULL;
1413 if (sbinfo->mpol) {
1414 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1415 mpol = sbinfo->mpol;
1416 mpol_get(mpol);
1417 spin_unlock(&sbinfo->stat_lock);
1418 }
1419 return mpol;
1420}
1421#else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1422static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1423{
1424}
1425static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1426{
1427 return NULL;
1428}
1429#endif /* CONFIG_NUMA && CONFIG_TMPFS */
1430#ifndef CONFIG_NUMA
1431#define vm_policy vm_private_data
1432#endif
1433
1434static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1435 struct shmem_inode_info *info, pgoff_t index)
1436{
1437 /* Create a pseudo vma that just contains the policy */
1438 vma_init(vma, NULL);
1439 /* Bias interleave by inode number to distribute better across nodes */
1440 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1441 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1442}
1443
1444static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1445{
1446 /* Drop reference taken by mpol_shared_policy_lookup() */
1447 mpol_cond_put(vma->vm_policy);
1448}
1449
1450static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1451 struct shmem_inode_info *info, pgoff_t index)
1452{
1453 struct vm_area_struct pvma;
1454 struct page *page;
1455 struct vm_fault vmf;
1456
1457 shmem_pseudo_vma_init(&pvma, info, index);
1458 vmf.vma = &pvma;
1459 vmf.address = 0;
1460 page = swap_cluster_readahead(swap, gfp, &vmf);
1461 shmem_pseudo_vma_destroy(&pvma);
1462
1463 return page;
1464}
1465
1466static struct page *shmem_alloc_hugepage(gfp_t gfp,
1467 struct shmem_inode_info *info, pgoff_t index)
1468{
1469 struct vm_area_struct pvma;
1470 struct address_space *mapping = info->vfs_inode.i_mapping;
1471 pgoff_t hindex;
1472 struct page *page;
1473
1474 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1475 return NULL;
1476
1477 hindex = round_down(index, HPAGE_PMD_NR);
1478 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1479 XA_PRESENT))
1480 return NULL;
1481
1482 shmem_pseudo_vma_init(&pvma, info, hindex);
1483 page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
1484 HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
1485 shmem_pseudo_vma_destroy(&pvma);
1486 if (page)
1487 prep_transhuge_page(page);
1488 return page;
1489}
1490
1491static struct page *shmem_alloc_page(gfp_t gfp,
1492 struct shmem_inode_info *info, pgoff_t index)
1493{
1494 struct vm_area_struct pvma;
1495 struct page *page;
1496
1497 shmem_pseudo_vma_init(&pvma, info, index);
1498 page = alloc_page_vma(gfp, &pvma, 0);
1499 shmem_pseudo_vma_destroy(&pvma);
1500
1501 return page;
1502}
1503
1504static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1505 struct inode *inode,
1506 pgoff_t index, bool huge)
1507{
1508 struct shmem_inode_info *info = SHMEM_I(inode);
1509 struct page *page;
1510 int nr;
1511 int err = -ENOSPC;
1512
1513 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1514 huge = false;
1515 nr = huge ? HPAGE_PMD_NR : 1;
1516
1517 if (!shmem_inode_acct_block(inode, nr))
1518 goto failed;
1519
1520 if (huge)
1521 page = shmem_alloc_hugepage(gfp, info, index);
1522 else
1523 page = shmem_alloc_page(gfp, info, index);
1524 if (page) {
1525 __SetPageLocked(page);
1526 __SetPageSwapBacked(page);
1527 return page;
1528 }
1529
1530 err = -ENOMEM;
1531 shmem_inode_unacct_blocks(inode, nr);
1532failed:
1533 return ERR_PTR(err);
1534}
1535
1536/*
1537 * When a page is moved from swapcache to shmem filecache (either by the
1538 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1539 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1540 * ignorance of the mapping it belongs to. If that mapping has special
1541 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1542 * we may need to copy to a suitable page before moving to filecache.
1543 *
1544 * In a future release, this may well be extended to respect cpuset and
1545 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1546 * but for now it is a simple matter of zone.
1547 */
1548static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1549{
1550 return page_zonenum(page) > gfp_zone(gfp);
1551}
1552
1553static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1554 struct shmem_inode_info *info, pgoff_t index)
1555{
1556 struct page *oldpage, *newpage;
1557 struct address_space *swap_mapping;
1558 swp_entry_t entry;
1559 pgoff_t swap_index;
1560 int error;
1561
1562 oldpage = *pagep;
1563 entry.val = page_private(oldpage);
1564 swap_index = swp_offset(entry);
1565 swap_mapping = page_mapping(oldpage);
1566
1567 /*
1568 * We have arrived here because our zones are constrained, so don't
1569 * limit chance of success by further cpuset and node constraints.
1570 */
1571 gfp &= ~GFP_CONSTRAINT_MASK;
1572 newpage = shmem_alloc_page(gfp, info, index);
1573 if (!newpage)
1574 return -ENOMEM;
1575
1576 get_page(newpage);
1577 copy_highpage(newpage, oldpage);
1578 flush_dcache_page(newpage);
1579
1580 __SetPageLocked(newpage);
1581 __SetPageSwapBacked(newpage);
1582 SetPageUptodate(newpage);
1583 set_page_private(newpage, entry.val);
1584 SetPageSwapCache(newpage);
1585
1586 /*
1587 * Our caller will very soon move newpage out of swapcache, but it's
1588 * a nice clean interface for us to replace oldpage by newpage there.
1589 */
1590 xa_lock_irq(&swap_mapping->i_pages);
1591 error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
1592 if (!error) {
1593 __inc_node_page_state(newpage, NR_FILE_PAGES);
1594 __dec_node_page_state(oldpage, NR_FILE_PAGES);
1595 }
1596 xa_unlock_irq(&swap_mapping->i_pages);
1597
1598 if (unlikely(error)) {
1599 /*
1600 * Is this possible? I think not, now that our callers check
1601 * both PageSwapCache and page_private after getting page lock;
1602 * but be defensive. Reverse old to newpage for clear and free.
1603 */
1604 oldpage = newpage;
1605 } else {
1606 mem_cgroup_migrate(oldpage, newpage);
1607 lru_cache_add_anon(newpage);
1608 *pagep = newpage;
1609 }
1610
1611 ClearPageSwapCache(oldpage);
1612 set_page_private(oldpage, 0);
1613
1614 unlock_page(oldpage);
1615 put_page(oldpage);
1616 put_page(oldpage);
1617 return error;
1618}
1619
1620/*
1621 * Swap in the page pointed to by *pagep.
1622 * Caller has to make sure that *pagep contains a valid swapped page.
1623 * Returns 0 and the page in pagep if success. On failure, returns the
1624 * the error code and NULL in *pagep.
1625 */
1626static int shmem_swapin_page(struct inode *inode, pgoff_t index,
1627 struct page **pagep, enum sgp_type sgp,
1628 gfp_t gfp, struct vm_area_struct *vma,
1629 vm_fault_t *fault_type)
1630{
1631 struct address_space *mapping = inode->i_mapping;
1632 struct shmem_inode_info *info = SHMEM_I(inode);
1633 struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm;
1634 struct mem_cgroup *memcg;
1635 struct page *page;
1636 swp_entry_t swap;
1637 int error;
1638
1639 VM_BUG_ON(!*pagep || !xa_is_value(*pagep));
1640 swap = radix_to_swp_entry(*pagep);
1641 *pagep = NULL;
1642
1643 /* Look it up and read it in.. */
1644 page = lookup_swap_cache(swap, NULL, 0);
1645 if (!page) {
1646 /* Or update major stats only when swapin succeeds?? */
1647 if (fault_type) {
1648 *fault_type |= VM_FAULT_MAJOR;
1649 count_vm_event(PGMAJFAULT);
1650 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1651 }
1652 /* Here we actually start the io */
1653 page = shmem_swapin(swap, gfp, info, index);
1654 if (!page) {
1655 error = -ENOMEM;
1656 goto failed;
1657 }
1658 }
1659
1660 /* We have to do this with page locked to prevent races */
1661 lock_page(page);
1662 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1663 !shmem_confirm_swap(mapping, index, swap)) {
1664 error = -EEXIST;
1665 goto unlock;
1666 }
1667 if (!PageUptodate(page)) {
1668 error = -EIO;
1669 goto failed;
1670 }
1671 wait_on_page_writeback(page);
1672
1673 if (shmem_should_replace_page(page, gfp)) {
1674 error = shmem_replace_page(&page, gfp, info, index);
1675 if (error)
1676 goto failed;
1677 }
1678
1679 error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg,
1680 false);
1681 if (!error) {
1682 error = shmem_add_to_page_cache(page, mapping, index,
1683 swp_to_radix_entry(swap), gfp);
1684 /*
1685 * We already confirmed swap under page lock, and make
1686 * no memory allocation here, so usually no possibility
1687 * of error; but free_swap_and_cache() only trylocks a
1688 * page, so it is just possible that the entry has been
1689 * truncated or holepunched since swap was confirmed.
1690 * shmem_undo_range() will have done some of the
1691 * unaccounting, now delete_from_swap_cache() will do
1692 * the rest.
1693 */
1694 if (error) {
1695 mem_cgroup_cancel_charge(page, memcg, false);
1696 delete_from_swap_cache(page);
1697 }
1698 }
1699 if (error)
1700 goto failed;
1701
1702 mem_cgroup_commit_charge(page, memcg, true, false);
1703
1704 spin_lock_irq(&info->lock);
1705 info->swapped--;
1706 shmem_recalc_inode(inode);
1707 spin_unlock_irq(&info->lock);
1708
1709 if (sgp == SGP_WRITE)
1710 mark_page_accessed(page);
1711
1712 delete_from_swap_cache(page);
1713 set_page_dirty(page);
1714 swap_free(swap);
1715
1716 *pagep = page;
1717 return 0;
1718failed:
1719 if (!shmem_confirm_swap(mapping, index, swap))
1720 error = -EEXIST;
1721unlock:
1722 if (page) {
1723 unlock_page(page);
1724 put_page(page);
1725 }
1726
1727 return error;
1728}
1729
1730/*
1731 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1732 *
1733 * If we allocate a new one we do not mark it dirty. That's up to the
1734 * vm. If we swap it in we mark it dirty since we also free the swap
1735 * entry since a page cannot live in both the swap and page cache.
1736 *
1737 * vmf and fault_type are only supplied by shmem_fault:
1738 * otherwise they are NULL.
1739 */
1740static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1741 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1742 struct vm_area_struct *vma, struct vm_fault *vmf,
1743 vm_fault_t *fault_type)
1744{
1745 struct address_space *mapping = inode->i_mapping;
1746 struct shmem_inode_info *info = SHMEM_I(inode);
1747 struct shmem_sb_info *sbinfo;
1748 struct mm_struct *charge_mm;
1749 struct mem_cgroup *memcg;
1750 struct page *page;
1751 enum sgp_type sgp_huge = sgp;
1752 pgoff_t hindex = index;
1753 int error;
1754 int once = 0;
1755 int alloced = 0;
1756
1757 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1758 return -EFBIG;
1759 if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
1760 sgp = SGP_CACHE;
1761repeat:
1762 if (sgp <= SGP_CACHE &&
1763 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1764 return -EINVAL;
1765 }
1766
1767 sbinfo = SHMEM_SB(inode->i_sb);
1768 charge_mm = vma ? vma->vm_mm : current->mm;
1769
1770 page = find_lock_entry(mapping, index);
1771 if (xa_is_value(page)) {
1772 error = shmem_swapin_page(inode, index, &page,
1773 sgp, gfp, vma, fault_type);
1774 if (error == -EEXIST)
1775 goto repeat;
1776
1777 *pagep = page;
1778 return error;
1779 }
1780
1781 if (page && sgp == SGP_WRITE)
1782 mark_page_accessed(page);
1783
1784 /* fallocated page? */
1785 if (page && !PageUptodate(page)) {
1786 if (sgp != SGP_READ)
1787 goto clear;
1788 unlock_page(page);
1789 put_page(page);
1790 page = NULL;
1791 }
1792 if (page || sgp == SGP_READ) {
1793 *pagep = page;
1794 return 0;
1795 }
1796
1797 /*
1798 * Fast cache lookup did not find it:
1799 * bring it back from swap or allocate.
1800 */
1801
1802 if (vma && userfaultfd_missing(vma)) {
1803 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1804 return 0;
1805 }
1806
1807 /* shmem_symlink() */
1808 if (mapping->a_ops != &shmem_aops)
1809 goto alloc_nohuge;
1810 if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
1811 goto alloc_nohuge;
1812 if (shmem_huge == SHMEM_HUGE_FORCE)
1813 goto alloc_huge;
1814 switch (sbinfo->huge) {
1815 loff_t i_size;
1816 pgoff_t off;
1817 case SHMEM_HUGE_NEVER:
1818 goto alloc_nohuge;
1819 case SHMEM_HUGE_WITHIN_SIZE:
1820 off = round_up(index, HPAGE_PMD_NR);
1821 i_size = round_up(i_size_read(inode), PAGE_SIZE);
1822 if (i_size >= HPAGE_PMD_SIZE &&
1823 i_size >> PAGE_SHIFT >= off)
1824 goto alloc_huge;
1825 /* fallthrough */
1826 case SHMEM_HUGE_ADVISE:
1827 if (sgp_huge == SGP_HUGE)
1828 goto alloc_huge;
1829 /* TODO: implement fadvise() hints */
1830 goto alloc_nohuge;
1831 }
1832
1833alloc_huge:
1834 page = shmem_alloc_and_acct_page(gfp, inode, index, true);
1835 if (IS_ERR(page)) {
1836alloc_nohuge:
1837 page = shmem_alloc_and_acct_page(gfp, inode,
1838 index, false);
1839 }
1840 if (IS_ERR(page)) {
1841 int retry = 5;
1842
1843 error = PTR_ERR(page);
1844 page = NULL;
1845 if (error != -ENOSPC)
1846 goto unlock;
1847 /*
1848 * Try to reclaim some space by splitting a huge page
1849 * beyond i_size on the filesystem.
1850 */
1851 while (retry--) {
1852 int ret;
1853
1854 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1855 if (ret == SHRINK_STOP)
1856 break;
1857 if (ret)
1858 goto alloc_nohuge;
1859 }
1860 goto unlock;
1861 }
1862
1863 if (PageTransHuge(page))
1864 hindex = round_down(index, HPAGE_PMD_NR);
1865 else
1866 hindex = index;
1867
1868 if (sgp == SGP_WRITE)
1869 __SetPageReferenced(page);
1870
1871 error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg,
1872 PageTransHuge(page));
1873 if (error)
1874 goto unacct;
1875 error = shmem_add_to_page_cache(page, mapping, hindex,
1876 NULL, gfp & GFP_RECLAIM_MASK);
1877 if (error) {
1878 mem_cgroup_cancel_charge(page, memcg,
1879 PageTransHuge(page));
1880 goto unacct;
1881 }
1882 mem_cgroup_commit_charge(page, memcg, false,
1883 PageTransHuge(page));
1884 lru_cache_add_anon(page);
1885
1886 spin_lock_irq(&info->lock);
1887 info->alloced += compound_nr(page);
1888 inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1889 shmem_recalc_inode(inode);
1890 spin_unlock_irq(&info->lock);
1891 alloced = true;
1892
1893 if (PageTransHuge(page) &&
1894 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1895 hindex + HPAGE_PMD_NR - 1) {
1896 /*
1897 * Part of the huge page is beyond i_size: subject
1898 * to shrink under memory pressure.
1899 */
1900 spin_lock(&sbinfo->shrinklist_lock);
1901 /*
1902 * _careful to defend against unlocked access to
1903 * ->shrink_list in shmem_unused_huge_shrink()
1904 */
1905 if (list_empty_careful(&info->shrinklist)) {
1906 list_add_tail(&info->shrinklist,
1907 &sbinfo->shrinklist);
1908 sbinfo->shrinklist_len++;
1909 }
1910 spin_unlock(&sbinfo->shrinklist_lock);
1911 }
1912
1913 /*
1914 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1915 */
1916 if (sgp == SGP_FALLOC)
1917 sgp = SGP_WRITE;
1918clear:
1919 /*
1920 * Let SGP_WRITE caller clear ends if write does not fill page;
1921 * but SGP_FALLOC on a page fallocated earlier must initialize
1922 * it now, lest undo on failure cancel our earlier guarantee.
1923 */
1924 if (sgp != SGP_WRITE && !PageUptodate(page)) {
1925 struct page *head = compound_head(page);
1926 int i;
1927
1928 for (i = 0; i < compound_nr(head); i++) {
1929 clear_highpage(head + i);
1930 flush_dcache_page(head + i);
1931 }
1932 SetPageUptodate(head);
1933 }
1934
1935 /* Perhaps the file has been truncated since we checked */
1936 if (sgp <= SGP_CACHE &&
1937 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1938 if (alloced) {
1939 ClearPageDirty(page);
1940 delete_from_page_cache(page);
1941 spin_lock_irq(&info->lock);
1942 shmem_recalc_inode(inode);
1943 spin_unlock_irq(&info->lock);
1944 }
1945 error = -EINVAL;
1946 goto unlock;
1947 }
1948 *pagep = page + index - hindex;
1949 return 0;
1950
1951 /*
1952 * Error recovery.
1953 */
1954unacct:
1955 shmem_inode_unacct_blocks(inode, compound_nr(page));
1956
1957 if (PageTransHuge(page)) {
1958 unlock_page(page);
1959 put_page(page);
1960 goto alloc_nohuge;
1961 }
1962unlock:
1963 if (page) {
1964 unlock_page(page);
1965 put_page(page);
1966 }
1967 if (error == -ENOSPC && !once++) {
1968 spin_lock_irq(&info->lock);
1969 shmem_recalc_inode(inode);
1970 spin_unlock_irq(&info->lock);
1971 goto repeat;
1972 }
1973 if (error == -EEXIST)
1974 goto repeat;
1975 return error;
1976}
1977
1978/*
1979 * This is like autoremove_wake_function, but it removes the wait queue
1980 * entry unconditionally - even if something else had already woken the
1981 * target.
1982 */
1983static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
1984{
1985 int ret = default_wake_function(wait, mode, sync, key);
1986 list_del_init(&wait->entry);
1987 return ret;
1988}
1989
1990static vm_fault_t shmem_fault(struct vm_fault *vmf)
1991{
1992 struct vm_area_struct *vma = vmf->vma;
1993 struct inode *inode = file_inode(vma->vm_file);
1994 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
1995 enum sgp_type sgp;
1996 int err;
1997 vm_fault_t ret = VM_FAULT_LOCKED;
1998
1999 /*
2000 * Trinity finds that probing a hole which tmpfs is punching can
2001 * prevent the hole-punch from ever completing: which in turn
2002 * locks writers out with its hold on i_mutex. So refrain from
2003 * faulting pages into the hole while it's being punched. Although
2004 * shmem_undo_range() does remove the additions, it may be unable to
2005 * keep up, as each new page needs its own unmap_mapping_range() call,
2006 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2007 *
2008 * It does not matter if we sometimes reach this check just before the
2009 * hole-punch begins, so that one fault then races with the punch:
2010 * we just need to make racing faults a rare case.
2011 *
2012 * The implementation below would be much simpler if we just used a
2013 * standard mutex or completion: but we cannot take i_mutex in fault,
2014 * and bloating every shmem inode for this unlikely case would be sad.
2015 */
2016 if (unlikely(inode->i_private)) {
2017 struct shmem_falloc *shmem_falloc;
2018
2019 spin_lock(&inode->i_lock);
2020 shmem_falloc = inode->i_private;
2021 if (shmem_falloc &&
2022 shmem_falloc->waitq &&
2023 vmf->pgoff >= shmem_falloc->start &&
2024 vmf->pgoff < shmem_falloc->next) {
2025 wait_queue_head_t *shmem_falloc_waitq;
2026 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2027
2028 ret = VM_FAULT_NOPAGE;
2029 if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
2030 !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
2031 /* It's polite to up mmap_sem if we can */
2032 up_read(&vma->vm_mm->mmap_sem);
2033 ret = VM_FAULT_RETRY;
2034 }
2035
2036 shmem_falloc_waitq = shmem_falloc->waitq;
2037 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2038 TASK_UNINTERRUPTIBLE);
2039 spin_unlock(&inode->i_lock);
2040 schedule();
2041
2042 /*
2043 * shmem_falloc_waitq points into the shmem_fallocate()
2044 * stack of the hole-punching task: shmem_falloc_waitq
2045 * is usually invalid by the time we reach here, but
2046 * finish_wait() does not dereference it in that case;
2047 * though i_lock needed lest racing with wake_up_all().
2048 */
2049 spin_lock(&inode->i_lock);
2050 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2051 spin_unlock(&inode->i_lock);
2052 return ret;
2053 }
2054 spin_unlock(&inode->i_lock);
2055 }
2056
2057 sgp = SGP_CACHE;
2058
2059 if ((vma->vm_flags & VM_NOHUGEPAGE) ||
2060 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
2061 sgp = SGP_NOHUGE;
2062 else if (vma->vm_flags & VM_HUGEPAGE)
2063 sgp = SGP_HUGE;
2064
2065 err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
2066 gfp, vma, vmf, &ret);
2067 if (err)
2068 return vmf_error(err);
2069 return ret;
2070}
2071
2072unsigned long shmem_get_unmapped_area(struct file *file,
2073 unsigned long uaddr, unsigned long len,
2074 unsigned long pgoff, unsigned long flags)
2075{
2076 unsigned long (*get_area)(struct file *,
2077 unsigned long, unsigned long, unsigned long, unsigned long);
2078 unsigned long addr;
2079 unsigned long offset;
2080 unsigned long inflated_len;
2081 unsigned long inflated_addr;
2082 unsigned long inflated_offset;
2083
2084 if (len > TASK_SIZE)
2085 return -ENOMEM;
2086
2087 get_area = current->mm->get_unmapped_area;
2088 addr = get_area(file, uaddr, len, pgoff, flags);
2089
2090 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
2091 return addr;
2092 if (IS_ERR_VALUE(addr))
2093 return addr;
2094 if (addr & ~PAGE_MASK)
2095 return addr;
2096 if (addr > TASK_SIZE - len)
2097 return addr;
2098
2099 if (shmem_huge == SHMEM_HUGE_DENY)
2100 return addr;
2101 if (len < HPAGE_PMD_SIZE)
2102 return addr;
2103 if (flags & MAP_FIXED)
2104 return addr;
2105 /*
2106 * Our priority is to support MAP_SHARED mapped hugely;
2107 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2108 * But if caller specified an address hint, respect that as before.
2109 */
2110 if (uaddr)
2111 return addr;
2112
2113 if (shmem_huge != SHMEM_HUGE_FORCE) {
2114 struct super_block *sb;
2115
2116 if (file) {
2117 VM_BUG_ON(file->f_op != &shmem_file_operations);
2118 sb = file_inode(file)->i_sb;
2119 } else {
2120 /*
2121 * Called directly from mm/mmap.c, or drivers/char/mem.c
2122 * for "/dev/zero", to create a shared anonymous object.
2123 */
2124 if (IS_ERR(shm_mnt))
2125 return addr;
2126 sb = shm_mnt->mnt_sb;
2127 }
2128 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2129 return addr;
2130 }
2131
2132 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2133 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2134 return addr;
2135 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2136 return addr;
2137
2138 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2139 if (inflated_len > TASK_SIZE)
2140 return addr;
2141 if (inflated_len < len)
2142 return addr;
2143
2144 inflated_addr = get_area(NULL, 0, inflated_len, 0, flags);
2145 if (IS_ERR_VALUE(inflated_addr))
2146 return addr;
2147 if (inflated_addr & ~PAGE_MASK)
2148 return addr;
2149
2150 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2151 inflated_addr += offset - inflated_offset;
2152 if (inflated_offset > offset)
2153 inflated_addr += HPAGE_PMD_SIZE;
2154
2155 if (inflated_addr > TASK_SIZE - len)
2156 return addr;
2157 return inflated_addr;
2158}
2159
2160#ifdef CONFIG_NUMA
2161static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2162{
2163 struct inode *inode = file_inode(vma->vm_file);
2164 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2165}
2166
2167static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2168 unsigned long addr)
2169{
2170 struct inode *inode = file_inode(vma->vm_file);
2171 pgoff_t index;
2172
2173 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2174 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2175}
2176#endif
2177
2178int shmem_lock(struct file *file, int lock, struct user_struct *user)
2179{
2180 struct inode *inode = file_inode(file);
2181 struct shmem_inode_info *info = SHMEM_I(inode);
2182 int retval = -ENOMEM;
2183
2184 spin_lock_irq(&info->lock);
2185 if (lock && !(info->flags & VM_LOCKED)) {
2186 if (!user_shm_lock(inode->i_size, user))
2187 goto out_nomem;
2188 info->flags |= VM_LOCKED;
2189 mapping_set_unevictable(file->f_mapping);
2190 }
2191 if (!lock && (info->flags & VM_LOCKED) && user) {
2192 user_shm_unlock(inode->i_size, user);
2193 info->flags &= ~VM_LOCKED;
2194 mapping_clear_unevictable(file->f_mapping);
2195 }
2196 retval = 0;
2197
2198out_nomem:
2199 spin_unlock_irq(&info->lock);
2200 return retval;
2201}
2202
2203static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2204{
2205 struct shmem_inode_info *info = SHMEM_I(file_inode(file));
2206
2207 if (info->seals & F_SEAL_FUTURE_WRITE) {
2208 /*
2209 * New PROT_WRITE and MAP_SHARED mmaps are not allowed when
2210 * "future write" seal active.
2211 */
2212 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
2213 return -EPERM;
2214
2215 /*
2216 * Since the F_SEAL_FUTURE_WRITE seals allow for a MAP_SHARED
2217 * read-only mapping, take care to not allow mprotect to revert
2218 * protections.
2219 */
2220 vma->vm_flags &= ~(VM_MAYWRITE);
2221 }
2222
2223 file_accessed(file);
2224 vma->vm_ops = &shmem_vm_ops;
2225 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
2226 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2227 (vma->vm_end & HPAGE_PMD_MASK)) {
2228 khugepaged_enter(vma, vma->vm_flags);
2229 }
2230 return 0;
2231}
2232
2233static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2234 umode_t mode, dev_t dev, unsigned long flags)
2235{
2236 struct inode *inode;
2237 struct shmem_inode_info *info;
2238 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2239
2240 if (shmem_reserve_inode(sb))
2241 return NULL;
2242
2243 inode = new_inode(sb);
2244 if (inode) {
2245 inode->i_ino = get_next_ino();
2246 inode_init_owner(inode, dir, mode);
2247 inode->i_blocks = 0;
2248 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2249 inode->i_generation = prandom_u32();
2250 info = SHMEM_I(inode);
2251 memset(info, 0, (char *)inode - (char *)info);
2252 spin_lock_init(&info->lock);
2253 atomic_set(&info->stop_eviction, 0);
2254 info->seals = F_SEAL_SEAL;
2255 info->flags = flags & VM_NORESERVE;
2256 INIT_LIST_HEAD(&info->shrinklist);
2257 INIT_LIST_HEAD(&info->swaplist);
2258 simple_xattrs_init(&info->xattrs);
2259 cache_no_acl(inode);
2260
2261 switch (mode & S_IFMT) {
2262 default:
2263 inode->i_op = &shmem_special_inode_operations;
2264 init_special_inode(inode, mode, dev);
2265 break;
2266 case S_IFREG:
2267 inode->i_mapping->a_ops = &shmem_aops;
2268 inode->i_op = &shmem_inode_operations;
2269 inode->i_fop = &shmem_file_operations;
2270 mpol_shared_policy_init(&info->policy,
2271 shmem_get_sbmpol(sbinfo));
2272 break;
2273 case S_IFDIR:
2274 inc_nlink(inode);
2275 /* Some things misbehave if size == 0 on a directory */
2276 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2277 inode->i_op = &shmem_dir_inode_operations;
2278 inode->i_fop = &simple_dir_operations;
2279 break;
2280 case S_IFLNK:
2281 /*
2282 * Must not load anything in the rbtree,
2283 * mpol_free_shared_policy will not be called.
2284 */
2285 mpol_shared_policy_init(&info->policy, NULL);
2286 break;
2287 }
2288
2289 lockdep_annotate_inode_mutex_key(inode);
2290 } else
2291 shmem_free_inode(sb);
2292 return inode;
2293}
2294
2295bool shmem_mapping(struct address_space *mapping)
2296{
2297 return mapping->a_ops == &shmem_aops;
2298}
2299
2300static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2301 pmd_t *dst_pmd,
2302 struct vm_area_struct *dst_vma,
2303 unsigned long dst_addr,
2304 unsigned long src_addr,
2305 bool zeropage,
2306 struct page **pagep)
2307{
2308 struct inode *inode = file_inode(dst_vma->vm_file);
2309 struct shmem_inode_info *info = SHMEM_I(inode);
2310 struct address_space *mapping = inode->i_mapping;
2311 gfp_t gfp = mapping_gfp_mask(mapping);
2312 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2313 struct mem_cgroup *memcg;
2314 spinlock_t *ptl;
2315 void *page_kaddr;
2316 struct page *page;
2317 pte_t _dst_pte, *dst_pte;
2318 int ret;
2319 pgoff_t offset, max_off;
2320
2321 ret = -ENOMEM;
2322 if (!shmem_inode_acct_block(inode, 1))
2323 goto out;
2324
2325 if (!*pagep) {
2326 page = shmem_alloc_page(gfp, info, pgoff);
2327 if (!page)
2328 goto out_unacct_blocks;
2329
2330 if (!zeropage) { /* mcopy_atomic */
2331 page_kaddr = kmap_atomic(page);
2332 ret = copy_from_user(page_kaddr,
2333 (const void __user *)src_addr,
2334 PAGE_SIZE);
2335 kunmap_atomic(page_kaddr);
2336
2337 /* fallback to copy_from_user outside mmap_sem */
2338 if (unlikely(ret)) {
2339 *pagep = page;
2340 shmem_inode_unacct_blocks(inode, 1);
2341 /* don't free the page */
2342 return -ENOENT;
2343 }
2344 } else { /* mfill_zeropage_atomic */
2345 clear_highpage(page);
2346 }
2347 } else {
2348 page = *pagep;
2349 *pagep = NULL;
2350 }
2351
2352 VM_BUG_ON(PageLocked(page) || PageSwapBacked(page));
2353 __SetPageLocked(page);
2354 __SetPageSwapBacked(page);
2355 __SetPageUptodate(page);
2356
2357 ret = -EFAULT;
2358 offset = linear_page_index(dst_vma, dst_addr);
2359 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2360 if (unlikely(offset >= max_off))
2361 goto out_release;
2362
2363 ret = mem_cgroup_try_charge_delay(page, dst_mm, gfp, &memcg, false);
2364 if (ret)
2365 goto out_release;
2366
2367 ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL,
2368 gfp & GFP_RECLAIM_MASK);
2369 if (ret)
2370 goto out_release_uncharge;
2371
2372 mem_cgroup_commit_charge(page, memcg, false, false);
2373
2374 _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
2375 if (dst_vma->vm_flags & VM_WRITE)
2376 _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
2377 else {
2378 /*
2379 * We don't set the pte dirty if the vma has no
2380 * VM_WRITE permission, so mark the page dirty or it
2381 * could be freed from under us. We could do it
2382 * unconditionally before unlock_page(), but doing it
2383 * only if VM_WRITE is not set is faster.
2384 */
2385 set_page_dirty(page);
2386 }
2387
2388 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
2389
2390 ret = -EFAULT;
2391 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2392 if (unlikely(offset >= max_off))
2393 goto out_release_uncharge_unlock;
2394
2395 ret = -EEXIST;
2396 if (!pte_none(*dst_pte))
2397 goto out_release_uncharge_unlock;
2398
2399 lru_cache_add_anon(page);
2400
2401 spin_lock(&info->lock);
2402 info->alloced++;
2403 inode->i_blocks += BLOCKS_PER_PAGE;
2404 shmem_recalc_inode(inode);
2405 spin_unlock(&info->lock);
2406
2407 inc_mm_counter(dst_mm, mm_counter_file(page));
2408 page_add_file_rmap(page, false);
2409 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
2410
2411 /* No need to invalidate - it was non-present before */
2412 update_mmu_cache(dst_vma, dst_addr, dst_pte);
2413 pte_unmap_unlock(dst_pte, ptl);
2414 unlock_page(page);
2415 ret = 0;
2416out:
2417 return ret;
2418out_release_uncharge_unlock:
2419 pte_unmap_unlock(dst_pte, ptl);
2420 ClearPageDirty(page);
2421 delete_from_page_cache(page);
2422out_release_uncharge:
2423 mem_cgroup_cancel_charge(page, memcg, false);
2424out_release:
2425 unlock_page(page);
2426 put_page(page);
2427out_unacct_blocks:
2428 shmem_inode_unacct_blocks(inode, 1);
2429 goto out;
2430}
2431
2432int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
2433 pmd_t *dst_pmd,
2434 struct vm_area_struct *dst_vma,
2435 unsigned long dst_addr,
2436 unsigned long src_addr,
2437 struct page **pagep)
2438{
2439 return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2440 dst_addr, src_addr, false, pagep);
2441}
2442
2443int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
2444 pmd_t *dst_pmd,
2445 struct vm_area_struct *dst_vma,
2446 unsigned long dst_addr)
2447{
2448 struct page *page = NULL;
2449
2450 return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2451 dst_addr, 0, true, &page);
2452}
2453
2454#ifdef CONFIG_TMPFS
2455static const struct inode_operations shmem_symlink_inode_operations;
2456static const struct inode_operations shmem_short_symlink_operations;
2457
2458#ifdef CONFIG_TMPFS_XATTR
2459static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2460#else
2461#define shmem_initxattrs NULL
2462#endif
2463
2464static int
2465shmem_write_begin(struct file *file, struct address_space *mapping,
2466 loff_t pos, unsigned len, unsigned flags,
2467 struct page **pagep, void **fsdata)
2468{
2469 struct inode *inode = mapping->host;
2470 struct shmem_inode_info *info = SHMEM_I(inode);
2471 pgoff_t index = pos >> PAGE_SHIFT;
2472
2473 /* i_mutex is held by caller */
2474 if (unlikely(info->seals & (F_SEAL_GROW |
2475 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2476 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2477 return -EPERM;
2478 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2479 return -EPERM;
2480 }
2481
2482 return shmem_getpage(inode, index, pagep, SGP_WRITE);
2483}
2484
2485static int
2486shmem_write_end(struct file *file, struct address_space *mapping,
2487 loff_t pos, unsigned len, unsigned copied,
2488 struct page *page, void *fsdata)
2489{
2490 struct inode *inode = mapping->host;
2491
2492 if (pos + copied > inode->i_size)
2493 i_size_write(inode, pos + copied);
2494
2495 if (!PageUptodate(page)) {
2496 struct page *head = compound_head(page);
2497 if (PageTransCompound(page)) {
2498 int i;
2499
2500 for (i = 0; i < HPAGE_PMD_NR; i++) {
2501 if (head + i == page)
2502 continue;
2503 clear_highpage(head + i);
2504 flush_dcache_page(head + i);
2505 }
2506 }
2507 if (copied < PAGE_SIZE) {
2508 unsigned from = pos & (PAGE_SIZE - 1);
2509 zero_user_segments(page, 0, from,
2510 from + copied, PAGE_SIZE);
2511 }
2512 SetPageUptodate(head);
2513 }
2514 set_page_dirty(page);
2515 unlock_page(page);
2516 put_page(page);
2517
2518 return copied;
2519}
2520
2521static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2522{
2523 struct file *file = iocb->ki_filp;
2524 struct inode *inode = file_inode(file);
2525 struct address_space *mapping = inode->i_mapping;
2526 pgoff_t index;
2527 unsigned long offset;
2528 enum sgp_type sgp = SGP_READ;
2529 int error = 0;
2530 ssize_t retval = 0;
2531 loff_t *ppos = &iocb->ki_pos;
2532
2533 /*
2534 * Might this read be for a stacking filesystem? Then when reading
2535 * holes of a sparse file, we actually need to allocate those pages,
2536 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2537 */
2538 if (!iter_is_iovec(to))
2539 sgp = SGP_CACHE;
2540
2541 index = *ppos >> PAGE_SHIFT;
2542 offset = *ppos & ~PAGE_MASK;
2543
2544 for (;;) {
2545 struct page *page = NULL;
2546 pgoff_t end_index;
2547 unsigned long nr, ret;
2548 loff_t i_size = i_size_read(inode);
2549
2550 end_index = i_size >> PAGE_SHIFT;
2551 if (index > end_index)
2552 break;
2553 if (index == end_index) {
2554 nr = i_size & ~PAGE_MASK;
2555 if (nr <= offset)
2556 break;
2557 }
2558
2559 error = shmem_getpage(inode, index, &page, sgp);
2560 if (error) {
2561 if (error == -EINVAL)
2562 error = 0;
2563 break;
2564 }
2565 if (page) {
2566 if (sgp == SGP_CACHE)
2567 set_page_dirty(page);
2568 unlock_page(page);
2569 }
2570
2571 /*
2572 * We must evaluate after, since reads (unlike writes)
2573 * are called without i_mutex protection against truncate
2574 */
2575 nr = PAGE_SIZE;
2576 i_size = i_size_read(inode);
2577 end_index = i_size >> PAGE_SHIFT;
2578 if (index == end_index) {
2579 nr = i_size & ~PAGE_MASK;
2580 if (nr <= offset) {
2581 if (page)
2582 put_page(page);
2583 break;
2584 }
2585 }
2586 nr -= offset;
2587
2588 if (page) {
2589 /*
2590 * If users can be writing to this page using arbitrary
2591 * virtual addresses, take care about potential aliasing
2592 * before reading the page on the kernel side.
2593 */
2594 if (mapping_writably_mapped(mapping))
2595 flush_dcache_page(page);
2596 /*
2597 * Mark the page accessed if we read the beginning.
2598 */
2599 if (!offset)
2600 mark_page_accessed(page);
2601 } else {
2602 page = ZERO_PAGE(0);
2603 get_page(page);
2604 }
2605
2606 /*
2607 * Ok, we have the page, and it's up-to-date, so
2608 * now we can copy it to user space...
2609 */
2610 ret = copy_page_to_iter(page, offset, nr, to);
2611 retval += ret;
2612 offset += ret;
2613 index += offset >> PAGE_SHIFT;
2614 offset &= ~PAGE_MASK;
2615
2616 put_page(page);
2617 if (!iov_iter_count(to))
2618 break;
2619 if (ret < nr) {
2620 error = -EFAULT;
2621 break;
2622 }
2623 cond_resched();
2624 }
2625
2626 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2627 file_accessed(file);
2628 return retval ? retval : error;
2629}
2630
2631/*
2632 * llseek SEEK_DATA or SEEK_HOLE through the page cache.
2633 */
2634static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
2635 pgoff_t index, pgoff_t end, int whence)
2636{
2637 struct page *page;
2638 struct pagevec pvec;
2639 pgoff_t indices[PAGEVEC_SIZE];
2640 bool done = false;
2641 int i;
2642
2643 pagevec_init(&pvec);
2644 pvec.nr = 1; /* start small: we may be there already */
2645 while (!done) {
2646 pvec.nr = find_get_entries(mapping, index,
2647 pvec.nr, pvec.pages, indices);
2648 if (!pvec.nr) {
2649 if (whence == SEEK_DATA)
2650 index = end;
2651 break;
2652 }
2653 for (i = 0; i < pvec.nr; i++, index++) {
2654 if (index < indices[i]) {
2655 if (whence == SEEK_HOLE) {
2656 done = true;
2657 break;
2658 }
2659 index = indices[i];
2660 }
2661 page = pvec.pages[i];
2662 if (page && !xa_is_value(page)) {
2663 if (!PageUptodate(page))
2664 page = NULL;
2665 }
2666 if (index >= end ||
2667 (page && whence == SEEK_DATA) ||
2668 (!page && whence == SEEK_HOLE)) {
2669 done = true;
2670 break;
2671 }
2672 }
2673 pagevec_remove_exceptionals(&pvec);
2674 pagevec_release(&pvec);
2675 pvec.nr = PAGEVEC_SIZE;
2676 cond_resched();
2677 }
2678 return index;
2679}
2680
2681static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2682{
2683 struct address_space *mapping = file->f_mapping;
2684 struct inode *inode = mapping->host;
2685 pgoff_t start, end;
2686 loff_t new_offset;
2687
2688 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2689 return generic_file_llseek_size(file, offset, whence,
2690 MAX_LFS_FILESIZE, i_size_read(inode));
2691 inode_lock(inode);
2692 /* We're holding i_mutex so we can access i_size directly */
2693
2694 if (offset < 0 || offset >= inode->i_size)
2695 offset = -ENXIO;
2696 else {
2697 start = offset >> PAGE_SHIFT;
2698 end = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2699 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
2700 new_offset <<= PAGE_SHIFT;
2701 if (new_offset > offset) {
2702 if (new_offset < inode->i_size)
2703 offset = new_offset;
2704 else if (whence == SEEK_DATA)
2705 offset = -ENXIO;
2706 else
2707 offset = inode->i_size;
2708 }
2709 }
2710
2711 if (offset >= 0)
2712 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2713 inode_unlock(inode);
2714 return offset;
2715}
2716
2717static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2718 loff_t len)
2719{
2720 struct inode *inode = file_inode(file);
2721 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2722 struct shmem_inode_info *info = SHMEM_I(inode);
2723 struct shmem_falloc shmem_falloc;
2724 pgoff_t start, index, end;
2725 int error;
2726
2727 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2728 return -EOPNOTSUPP;
2729
2730 inode_lock(inode);
2731
2732 if (mode & FALLOC_FL_PUNCH_HOLE) {
2733 struct address_space *mapping = file->f_mapping;
2734 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2735 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2736 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2737
2738 /* protected by i_mutex */
2739 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
2740 error = -EPERM;
2741 goto out;
2742 }
2743
2744 shmem_falloc.waitq = &shmem_falloc_waitq;
2745 shmem_falloc.start = unmap_start >> PAGE_SHIFT;
2746 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2747 spin_lock(&inode->i_lock);
2748 inode->i_private = &shmem_falloc;
2749 spin_unlock(&inode->i_lock);
2750
2751 if ((u64)unmap_end > (u64)unmap_start)
2752 unmap_mapping_range(mapping, unmap_start,
2753 1 + unmap_end - unmap_start, 0);
2754 shmem_truncate_range(inode, offset, offset + len - 1);
2755 /* No need to unmap again: hole-punching leaves COWed pages */
2756
2757 spin_lock(&inode->i_lock);
2758 inode->i_private = NULL;
2759 wake_up_all(&shmem_falloc_waitq);
2760 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2761 spin_unlock(&inode->i_lock);
2762 error = 0;
2763 goto out;
2764 }
2765
2766 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2767 error = inode_newsize_ok(inode, offset + len);
2768 if (error)
2769 goto out;
2770
2771 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2772 error = -EPERM;
2773 goto out;
2774 }
2775
2776 start = offset >> PAGE_SHIFT;
2777 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2778 /* Try to avoid a swapstorm if len is impossible to satisfy */
2779 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2780 error = -ENOSPC;
2781 goto out;
2782 }
2783
2784 shmem_falloc.waitq = NULL;
2785 shmem_falloc.start = start;
2786 shmem_falloc.next = start;
2787 shmem_falloc.nr_falloced = 0;
2788 shmem_falloc.nr_unswapped = 0;
2789 spin_lock(&inode->i_lock);
2790 inode->i_private = &shmem_falloc;
2791 spin_unlock(&inode->i_lock);
2792
2793 for (index = start; index < end; index++) {
2794 struct page *page;
2795
2796 /*
2797 * Good, the fallocate(2) manpage permits EINTR: we may have
2798 * been interrupted because we are using up too much memory.
2799 */
2800 if (signal_pending(current))
2801 error = -EINTR;
2802 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2803 error = -ENOMEM;
2804 else
2805 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2806 if (error) {
2807 /* Remove the !PageUptodate pages we added */
2808 if (index > start) {
2809 shmem_undo_range(inode,
2810 (loff_t)start << PAGE_SHIFT,
2811 ((loff_t)index << PAGE_SHIFT) - 1, true);
2812 }
2813 goto undone;
2814 }
2815
2816 /*
2817 * Inform shmem_writepage() how far we have reached.
2818 * No need for lock or barrier: we have the page lock.
2819 */
2820 shmem_falloc.next++;
2821 if (!PageUptodate(page))
2822 shmem_falloc.nr_falloced++;
2823
2824 /*
2825 * If !PageUptodate, leave it that way so that freeable pages
2826 * can be recognized if we need to rollback on error later.
2827 * But set_page_dirty so that memory pressure will swap rather
2828 * than free the pages we are allocating (and SGP_CACHE pages
2829 * might still be clean: we now need to mark those dirty too).
2830 */
2831 set_page_dirty(page);
2832 unlock_page(page);
2833 put_page(page);
2834 cond_resched();
2835 }
2836
2837 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2838 i_size_write(inode, offset + len);
2839 inode->i_ctime = current_time(inode);
2840undone:
2841 spin_lock(&inode->i_lock);
2842 inode->i_private = NULL;
2843 spin_unlock(&inode->i_lock);
2844out:
2845 inode_unlock(inode);
2846 return error;
2847}
2848
2849static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2850{
2851 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2852
2853 buf->f_type = TMPFS_MAGIC;
2854 buf->f_bsize = PAGE_SIZE;
2855 buf->f_namelen = NAME_MAX;
2856 if (sbinfo->max_blocks) {
2857 buf->f_blocks = sbinfo->max_blocks;
2858 buf->f_bavail =
2859 buf->f_bfree = sbinfo->max_blocks -
2860 percpu_counter_sum(&sbinfo->used_blocks);
2861 }
2862 if (sbinfo->max_inodes) {
2863 buf->f_files = sbinfo->max_inodes;
2864 buf->f_ffree = sbinfo->free_inodes;
2865 }
2866 /* else leave those fields 0 like simple_statfs */
2867 return 0;
2868}
2869
2870/*
2871 * File creation. Allocate an inode, and we're done..
2872 */
2873static int
2874shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
2875{
2876 struct inode *inode;
2877 int error = -ENOSPC;
2878
2879 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2880 if (inode) {
2881 error = simple_acl_create(dir, inode);
2882 if (error)
2883 goto out_iput;
2884 error = security_inode_init_security(inode, dir,
2885 &dentry->d_name,
2886 shmem_initxattrs, NULL);
2887 if (error && error != -EOPNOTSUPP)
2888 goto out_iput;
2889
2890 error = 0;
2891 dir->i_size += BOGO_DIRENT_SIZE;
2892 dir->i_ctime = dir->i_mtime = current_time(dir);
2893 d_instantiate(dentry, inode);
2894 dget(dentry); /* Extra count - pin the dentry in core */
2895 }
2896 return error;
2897out_iput:
2898 iput(inode);
2899 return error;
2900}
2901
2902static int
2903shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
2904{
2905 struct inode *inode;
2906 int error = -ENOSPC;
2907
2908 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2909 if (inode) {
2910 error = security_inode_init_security(inode, dir,
2911 NULL,
2912 shmem_initxattrs, NULL);
2913 if (error && error != -EOPNOTSUPP)
2914 goto out_iput;
2915 error = simple_acl_create(dir, inode);
2916 if (error)
2917 goto out_iput;
2918 d_tmpfile(dentry, inode);
2919 }
2920 return error;
2921out_iput:
2922 iput(inode);
2923 return error;
2924}
2925
2926static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
2927{
2928 int error;
2929
2930 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
2931 return error;
2932 inc_nlink(dir);
2933 return 0;
2934}
2935
2936static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
2937 bool excl)
2938{
2939 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
2940}
2941
2942/*
2943 * Link a file..
2944 */
2945static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2946{
2947 struct inode *inode = d_inode(old_dentry);
2948 int ret = 0;
2949
2950 /*
2951 * No ordinary (disk based) filesystem counts links as inodes;
2952 * but each new link needs a new dentry, pinning lowmem, and
2953 * tmpfs dentries cannot be pruned until they are unlinked.
2954 * But if an O_TMPFILE file is linked into the tmpfs, the
2955 * first link must skip that, to get the accounting right.
2956 */
2957 if (inode->i_nlink) {
2958 ret = shmem_reserve_inode(inode->i_sb);
2959 if (ret)
2960 goto out;
2961 }
2962
2963 dir->i_size += BOGO_DIRENT_SIZE;
2964 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2965 inc_nlink(inode);
2966 ihold(inode); /* New dentry reference */
2967 dget(dentry); /* Extra pinning count for the created dentry */
2968 d_instantiate(dentry, inode);
2969out:
2970 return ret;
2971}
2972
2973static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2974{
2975 struct inode *inode = d_inode(dentry);
2976
2977 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2978 shmem_free_inode(inode->i_sb);
2979
2980 dir->i_size -= BOGO_DIRENT_SIZE;
2981 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2982 drop_nlink(inode);
2983 dput(dentry); /* Undo the count from "create" - this does all the work */
2984 return 0;
2985}
2986
2987static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2988{
2989 if (!simple_empty(dentry))
2990 return -ENOTEMPTY;
2991
2992 drop_nlink(d_inode(dentry));
2993 drop_nlink(dir);
2994 return shmem_unlink(dir, dentry);
2995}
2996
2997static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
2998{
2999 bool old_is_dir = d_is_dir(old_dentry);
3000 bool new_is_dir = d_is_dir(new_dentry);
3001
3002 if (old_dir != new_dir && old_is_dir != new_is_dir) {
3003 if (old_is_dir) {
3004 drop_nlink(old_dir);
3005 inc_nlink(new_dir);
3006 } else {
3007 drop_nlink(new_dir);
3008 inc_nlink(old_dir);
3009 }
3010 }
3011 old_dir->i_ctime = old_dir->i_mtime =
3012 new_dir->i_ctime = new_dir->i_mtime =
3013 d_inode(old_dentry)->i_ctime =
3014 d_inode(new_dentry)->i_ctime = current_time(old_dir);
3015
3016 return 0;
3017}
3018
3019static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
3020{
3021 struct dentry *whiteout;
3022 int error;
3023
3024 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3025 if (!whiteout)
3026 return -ENOMEM;
3027
3028 error = shmem_mknod(old_dir, whiteout,
3029 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3030 dput(whiteout);
3031 if (error)
3032 return error;
3033
3034 /*
3035 * Cheat and hash the whiteout while the old dentry is still in
3036 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3037 *
3038 * d_lookup() will consistently find one of them at this point,
3039 * not sure which one, but that isn't even important.
3040 */
3041 d_rehash(whiteout);
3042 return 0;
3043}
3044
3045/*
3046 * The VFS layer already does all the dentry stuff for rename,
3047 * we just have to decrement the usage count for the target if
3048 * it exists so that the VFS layer correctly free's it when it
3049 * gets overwritten.
3050 */
3051static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
3052{
3053 struct inode *inode = d_inode(old_dentry);
3054 int they_are_dirs = S_ISDIR(inode->i_mode);
3055
3056 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3057 return -EINVAL;
3058
3059 if (flags & RENAME_EXCHANGE)
3060 return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
3061
3062 if (!simple_empty(new_dentry))
3063 return -ENOTEMPTY;
3064
3065 if (flags & RENAME_WHITEOUT) {
3066 int error;
3067
3068 error = shmem_whiteout(old_dir, old_dentry);
3069 if (error)
3070 return error;
3071 }
3072
3073 if (d_really_is_positive(new_dentry)) {
3074 (void) shmem_unlink(new_dir, new_dentry);
3075 if (they_are_dirs) {
3076 drop_nlink(d_inode(new_dentry));
3077 drop_nlink(old_dir);
3078 }
3079 } else if (they_are_dirs) {
3080 drop_nlink(old_dir);
3081 inc_nlink(new_dir);
3082 }
3083
3084 old_dir->i_size -= BOGO_DIRENT_SIZE;
3085 new_dir->i_size += BOGO_DIRENT_SIZE;
3086 old_dir->i_ctime = old_dir->i_mtime =
3087 new_dir->i_ctime = new_dir->i_mtime =
3088 inode->i_ctime = current_time(old_dir);
3089 return 0;
3090}
3091
3092static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
3093{
3094 int error;
3095 int len;
3096 struct inode *inode;
3097 struct page *page;
3098
3099 len = strlen(symname) + 1;
3100 if (len > PAGE_SIZE)
3101 return -ENAMETOOLONG;
3102
3103 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0,
3104 VM_NORESERVE);
3105 if (!inode)
3106 return -ENOSPC;
3107
3108 error = security_inode_init_security(inode, dir, &dentry->d_name,
3109 shmem_initxattrs, NULL);
3110 if (error) {
3111 if (error != -EOPNOTSUPP) {
3112 iput(inode);
3113 return error;
3114 }
3115 error = 0;
3116 }
3117
3118 inode->i_size = len-1;
3119 if (len <= SHORT_SYMLINK_LEN) {
3120 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3121 if (!inode->i_link) {
3122 iput(inode);
3123 return -ENOMEM;
3124 }
3125 inode->i_op = &shmem_short_symlink_operations;
3126 } else {
3127 inode_nohighmem(inode);
3128 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3129 if (error) {
3130 iput(inode);
3131 return error;
3132 }
3133 inode->i_mapping->a_ops = &shmem_aops;
3134 inode->i_op = &shmem_symlink_inode_operations;
3135 memcpy(page_address(page), symname, len);
3136 SetPageUptodate(page);
3137 set_page_dirty(page);
3138 unlock_page(page);
3139 put_page(page);
3140 }
3141 dir->i_size += BOGO_DIRENT_SIZE;
3142 dir->i_ctime = dir->i_mtime = current_time(dir);
3143 d_instantiate(dentry, inode);
3144 dget(dentry);
3145 return 0;
3146}
3147
3148static void shmem_put_link(void *arg)
3149{
3150 mark_page_accessed(arg);
3151 put_page(arg);
3152}
3153
3154static const char *shmem_get_link(struct dentry *dentry,
3155 struct inode *inode,
3156 struct delayed_call *done)
3157{
3158 struct page *page = NULL;
3159 int error;
3160 if (!dentry) {
3161 page = find_get_page(inode->i_mapping, 0);
3162 if (!page)
3163 return ERR_PTR(-ECHILD);
3164 if (!PageUptodate(page)) {
3165 put_page(page);
3166 return ERR_PTR(-ECHILD);
3167 }
3168 } else {
3169 error = shmem_getpage(inode, 0, &page, SGP_READ);
3170 if (error)
3171 return ERR_PTR(error);
3172 unlock_page(page);
3173 }
3174 set_delayed_call(done, shmem_put_link, page);
3175 return page_address(page);
3176}
3177
3178#ifdef CONFIG_TMPFS_XATTR
3179/*
3180 * Superblocks without xattr inode operations may get some security.* xattr
3181 * support from the LSM "for free". As soon as we have any other xattrs
3182 * like ACLs, we also need to implement the security.* handlers at
3183 * filesystem level, though.
3184 */
3185
3186/*
3187 * Callback for security_inode_init_security() for acquiring xattrs.
3188 */
3189static int shmem_initxattrs(struct inode *inode,
3190 const struct xattr *xattr_array,
3191 void *fs_info)
3192{
3193 struct shmem_inode_info *info = SHMEM_I(inode);
3194 const struct xattr *xattr;
3195 struct simple_xattr *new_xattr;
3196 size_t len;
3197
3198 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3199 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3200 if (!new_xattr)
3201 return -ENOMEM;
3202
3203 len = strlen(xattr->name) + 1;
3204 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3205 GFP_KERNEL);
3206 if (!new_xattr->name) {
3207 kfree(new_xattr);
3208 return -ENOMEM;
3209 }
3210
3211 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3212 XATTR_SECURITY_PREFIX_LEN);
3213 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3214 xattr->name, len);
3215
3216 simple_xattr_list_add(&info->xattrs, new_xattr);
3217 }
3218
3219 return 0;
3220}
3221
3222static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3223 struct dentry *unused, struct inode *inode,
3224 const char *name, void *buffer, size_t size)
3225{
3226 struct shmem_inode_info *info = SHMEM_I(inode);
3227
3228 name = xattr_full_name(handler, name);
3229 return simple_xattr_get(&info->xattrs, name, buffer, size);
3230}
3231
3232static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3233 struct dentry *unused, struct inode *inode,
3234 const char *name, const void *value,
3235 size_t size, int flags)
3236{
3237 struct shmem_inode_info *info = SHMEM_I(inode);
3238
3239 name = xattr_full_name(handler, name);
3240 return simple_xattr_set(&info->xattrs, name, value, size, flags);
3241}
3242
3243static const struct xattr_handler shmem_security_xattr_handler = {
3244 .prefix = XATTR_SECURITY_PREFIX,
3245 .get = shmem_xattr_handler_get,
3246 .set = shmem_xattr_handler_set,
3247};
3248
3249static const struct xattr_handler shmem_trusted_xattr_handler = {
3250 .prefix = XATTR_TRUSTED_PREFIX,
3251 .get = shmem_xattr_handler_get,
3252 .set = shmem_xattr_handler_set,
3253};
3254
3255static const struct xattr_handler *shmem_xattr_handlers[] = {
3256#ifdef CONFIG_TMPFS_POSIX_ACL
3257 &posix_acl_access_xattr_handler,
3258 &posix_acl_default_xattr_handler,
3259#endif
3260 &shmem_security_xattr_handler,
3261 &shmem_trusted_xattr_handler,
3262 NULL
3263};
3264
3265static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3266{
3267 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3268 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3269}
3270#endif /* CONFIG_TMPFS_XATTR */
3271
3272static const struct inode_operations shmem_short_symlink_operations = {
3273 .get_link = simple_get_link,
3274#ifdef CONFIG_TMPFS_XATTR
3275 .listxattr = shmem_listxattr,
3276#endif
3277};
3278
3279static const struct inode_operations shmem_symlink_inode_operations = {
3280 .get_link = shmem_get_link,
3281#ifdef CONFIG_TMPFS_XATTR
3282 .listxattr = shmem_listxattr,
3283#endif
3284};
3285
3286static struct dentry *shmem_get_parent(struct dentry *child)
3287{
3288 return ERR_PTR(-ESTALE);
3289}
3290
3291static int shmem_match(struct inode *ino, void *vfh)
3292{
3293 __u32 *fh = vfh;
3294 __u64 inum = fh[2];
3295 inum = (inum << 32) | fh[1];
3296 return ino->i_ino == inum && fh[0] == ino->i_generation;
3297}
3298
3299/* Find any alias of inode, but prefer a hashed alias */
3300static struct dentry *shmem_find_alias(struct inode *inode)
3301{
3302 struct dentry *alias = d_find_alias(inode);
3303
3304 return alias ?: d_find_any_alias(inode);
3305}
3306
3307
3308static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3309 struct fid *fid, int fh_len, int fh_type)
3310{
3311 struct inode *inode;
3312 struct dentry *dentry = NULL;
3313 u64 inum;
3314
3315 if (fh_len < 3)
3316 return NULL;
3317
3318 inum = fid->raw[2];
3319 inum = (inum << 32) | fid->raw[1];
3320
3321 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3322 shmem_match, fid->raw);
3323 if (inode) {
3324 dentry = shmem_find_alias(inode);
3325 iput(inode);
3326 }
3327
3328 return dentry;
3329}
3330
3331static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3332 struct inode *parent)
3333{
3334 if (*len < 3) {
3335 *len = 3;
3336 return FILEID_INVALID;
3337 }
3338
3339 if (inode_unhashed(inode)) {
3340 /* Unfortunately insert_inode_hash is not idempotent,
3341 * so as we hash inodes here rather than at creation
3342 * time, we need a lock to ensure we only try
3343 * to do it once
3344 */
3345 static DEFINE_SPINLOCK(lock);
3346 spin_lock(&lock);
3347 if (inode_unhashed(inode))
3348 __insert_inode_hash(inode,
3349 inode->i_ino + inode->i_generation);
3350 spin_unlock(&lock);
3351 }
3352
3353 fh[0] = inode->i_generation;
3354 fh[1] = inode->i_ino;
3355 fh[2] = ((__u64)inode->i_ino) >> 32;
3356
3357 *len = 3;
3358 return 1;
3359}
3360
3361static const struct export_operations shmem_export_ops = {
3362 .get_parent = shmem_get_parent,
3363 .encode_fh = shmem_encode_fh,
3364 .fh_to_dentry = shmem_fh_to_dentry,
3365};
3366
3367enum shmem_param {
3368 Opt_gid,
3369 Opt_huge,
3370 Opt_mode,
3371 Opt_mpol,
3372 Opt_nr_blocks,
3373 Opt_nr_inodes,
3374 Opt_size,
3375 Opt_uid,
3376};
3377
3378static const struct fs_parameter_spec shmem_param_specs[] = {
3379 fsparam_u32 ("gid", Opt_gid),
3380 fsparam_enum ("huge", Opt_huge),
3381 fsparam_u32oct("mode", Opt_mode),
3382 fsparam_string("mpol", Opt_mpol),
3383 fsparam_string("nr_blocks", Opt_nr_blocks),
3384 fsparam_string("nr_inodes", Opt_nr_inodes),
3385 fsparam_string("size", Opt_size),
3386 fsparam_u32 ("uid", Opt_uid),
3387 {}
3388};
3389
3390static const struct fs_parameter_enum shmem_param_enums[] = {
3391 { Opt_huge, "never", SHMEM_HUGE_NEVER },
3392 { Opt_huge, "always", SHMEM_HUGE_ALWAYS },
3393 { Opt_huge, "within_size", SHMEM_HUGE_WITHIN_SIZE },
3394 { Opt_huge, "advise", SHMEM_HUGE_ADVISE },
3395 {}
3396};
3397
3398const struct fs_parameter_description shmem_fs_parameters = {
3399 .name = "tmpfs",
3400 .specs = shmem_param_specs,
3401 .enums = shmem_param_enums,
3402};
3403
3404static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3405{
3406 struct shmem_options *ctx = fc->fs_private;
3407 struct fs_parse_result result;
3408 unsigned long long size;
3409 char *rest;
3410 int opt;
3411
3412 opt = fs_parse(fc, &shmem_fs_parameters, param, &result);
3413 if (opt < 0)
3414 return opt;
3415
3416 switch (opt) {
3417 case Opt_size:
3418 size = memparse(param->string, &rest);
3419 if (*rest == '%') {
3420 size <<= PAGE_SHIFT;
3421 size *= totalram_pages();
3422 do_div(size, 100);
3423 rest++;
3424 }
3425 if (*rest)
3426 goto bad_value;
3427 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3428 ctx->seen |= SHMEM_SEEN_BLOCKS;
3429 break;
3430 case Opt_nr_blocks:
3431 ctx->blocks = memparse(param->string, &rest);
3432 if (*rest)
3433 goto bad_value;
3434 ctx->seen |= SHMEM_SEEN_BLOCKS;
3435 break;
3436 case Opt_nr_inodes:
3437 ctx->inodes = memparse(param->string, &rest);
3438 if (*rest)
3439 goto bad_value;
3440 ctx->seen |= SHMEM_SEEN_INODES;
3441 break;
3442 case Opt_mode:
3443 ctx->mode = result.uint_32 & 07777;
3444 break;
3445 case Opt_uid:
3446 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
3447 if (!uid_valid(ctx->uid))
3448 goto bad_value;
3449 break;
3450 case Opt_gid:
3451 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
3452 if (!gid_valid(ctx->gid))
3453 goto bad_value;
3454 break;
3455 case Opt_huge:
3456 ctx->huge = result.uint_32;
3457 if (ctx->huge != SHMEM_HUGE_NEVER &&
3458 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
3459 has_transparent_hugepage()))
3460 goto unsupported_parameter;
3461 ctx->seen |= SHMEM_SEEN_HUGE;
3462 break;
3463 case Opt_mpol:
3464 if (IS_ENABLED(CONFIG_NUMA)) {
3465 mpol_put(ctx->mpol);
3466 ctx->mpol = NULL;
3467 if (mpol_parse_str(param->string, &ctx->mpol))
3468 goto bad_value;
3469 break;
3470 }
3471 goto unsupported_parameter;
3472 }
3473 return 0;
3474
3475unsupported_parameter:
3476 return invalf(fc, "tmpfs: Unsupported parameter '%s'", param->key);
3477bad_value:
3478 return invalf(fc, "tmpfs: Bad value for '%s'", param->key);
3479}
3480
3481static int shmem_parse_options(struct fs_context *fc, void *data)
3482{
3483 char *options = data;
3484
3485 if (options) {
3486 int err = security_sb_eat_lsm_opts(options, &fc->security);
3487 if (err)
3488 return err;
3489 }
3490
3491 while (options != NULL) {
3492 char *this_char = options;
3493 for (;;) {
3494 /*
3495 * NUL-terminate this option: unfortunately,
3496 * mount options form a comma-separated list,
3497 * but mpol's nodelist may also contain commas.
3498 */
3499 options = strchr(options, ',');
3500 if (options == NULL)
3501 break;
3502 options++;
3503 if (!isdigit(*options)) {
3504 options[-1] = '\0';
3505 break;
3506 }
3507 }
3508 if (*this_char) {
3509 char *value = strchr(this_char,'=');
3510 size_t len = 0;
3511 int err;
3512
3513 if (value) {
3514 *value++ = '\0';
3515 len = strlen(value);
3516 }
3517 err = vfs_parse_fs_string(fc, this_char, value, len);
3518 if (err < 0)
3519 return err;
3520 }
3521 }
3522 return 0;
3523}
3524
3525/*
3526 * Reconfigure a shmem filesystem.
3527 *
3528 * Note that we disallow change from limited->unlimited blocks/inodes while any
3529 * are in use; but we must separately disallow unlimited->limited, because in
3530 * that case we have no record of how much is already in use.
3531 */
3532static int shmem_reconfigure(struct fs_context *fc)
3533{
3534 struct shmem_options *ctx = fc->fs_private;
3535 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
3536 unsigned long inodes;
3537 const char *err;
3538
3539 spin_lock(&sbinfo->stat_lock);
3540 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3541 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
3542 if (!sbinfo->max_blocks) {
3543 err = "Cannot retroactively limit size";
3544 goto out;
3545 }
3546 if (percpu_counter_compare(&sbinfo->used_blocks,
3547 ctx->blocks) > 0) {
3548 err = "Too small a size for current use";
3549 goto out;
3550 }
3551 }
3552 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
3553 if (!sbinfo->max_inodes) {
3554 err = "Cannot retroactively limit inodes";
3555 goto out;
3556 }
3557 if (ctx->inodes < inodes) {
3558 err = "Too few inodes for current use";
3559 goto out;
3560 }
3561 }
3562
3563 if (ctx->seen & SHMEM_SEEN_HUGE)
3564 sbinfo->huge = ctx->huge;
3565 if (ctx->seen & SHMEM_SEEN_BLOCKS)
3566 sbinfo->max_blocks = ctx->blocks;
3567 if (ctx->seen & SHMEM_SEEN_INODES) {
3568 sbinfo->max_inodes = ctx->inodes;
3569 sbinfo->free_inodes = ctx->inodes - inodes;
3570 }
3571
3572 /*
3573 * Preserve previous mempolicy unless mpol remount option was specified.
3574 */
3575 if (ctx->mpol) {
3576 mpol_put(sbinfo->mpol);
3577 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
3578 ctx->mpol = NULL;
3579 }
3580 spin_unlock(&sbinfo->stat_lock);
3581 return 0;
3582out:
3583 spin_unlock(&sbinfo->stat_lock);
3584 return invalf(fc, "tmpfs: %s", err);
3585}
3586
3587static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3588{
3589 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3590
3591 if (sbinfo->max_blocks != shmem_default_max_blocks())
3592 seq_printf(seq, ",size=%luk",
3593 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3594 if (sbinfo->max_inodes != shmem_default_max_inodes())
3595 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3596 if (sbinfo->mode != (0777 | S_ISVTX))
3597 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3598 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3599 seq_printf(seq, ",uid=%u",
3600 from_kuid_munged(&init_user_ns, sbinfo->uid));
3601 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3602 seq_printf(seq, ",gid=%u",
3603 from_kgid_munged(&init_user_ns, sbinfo->gid));
3604#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3605 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3606 if (sbinfo->huge)
3607 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3608#endif
3609 shmem_show_mpol(seq, sbinfo->mpol);
3610 return 0;
3611}
3612
3613#endif /* CONFIG_TMPFS */
3614
3615static void shmem_put_super(struct super_block *sb)
3616{
3617 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3618
3619 percpu_counter_destroy(&sbinfo->used_blocks);
3620 mpol_put(sbinfo->mpol);
3621 kfree(sbinfo);
3622 sb->s_fs_info = NULL;
3623}
3624
3625static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
3626{
3627 struct shmem_options *ctx = fc->fs_private;
3628 struct inode *inode;
3629 struct shmem_sb_info *sbinfo;
3630 int err = -ENOMEM;
3631
3632 /* Round up to L1_CACHE_BYTES to resist false sharing */
3633 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3634 L1_CACHE_BYTES), GFP_KERNEL);
3635 if (!sbinfo)
3636 return -ENOMEM;
3637
3638 sb->s_fs_info = sbinfo;
3639
3640#ifdef CONFIG_TMPFS
3641 /*
3642 * Per default we only allow half of the physical ram per
3643 * tmpfs instance, limiting inodes to one per page of lowmem;
3644 * but the internal instance is left unlimited.
3645 */
3646 if (!(sb->s_flags & SB_KERNMOUNT)) {
3647 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
3648 ctx->blocks = shmem_default_max_blocks();
3649 if (!(ctx->seen & SHMEM_SEEN_INODES))
3650 ctx->inodes = shmem_default_max_inodes();
3651 } else {
3652 sb->s_flags |= SB_NOUSER;
3653 }
3654 sb->s_export_op = &shmem_export_ops;
3655 sb->s_flags |= SB_NOSEC;
3656#else
3657 sb->s_flags |= SB_NOUSER;
3658#endif
3659 sbinfo->max_blocks = ctx->blocks;
3660 sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
3661 sbinfo->uid = ctx->uid;
3662 sbinfo->gid = ctx->gid;
3663 sbinfo->mode = ctx->mode;
3664 sbinfo->huge = ctx->huge;
3665 sbinfo->mpol = ctx->mpol;
3666 ctx->mpol = NULL;
3667
3668 spin_lock_init(&sbinfo->stat_lock);
3669 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3670 goto failed;
3671 spin_lock_init(&sbinfo->shrinklist_lock);
3672 INIT_LIST_HEAD(&sbinfo->shrinklist);
3673
3674 sb->s_maxbytes = MAX_LFS_FILESIZE;
3675 sb->s_blocksize = PAGE_SIZE;
3676 sb->s_blocksize_bits = PAGE_SHIFT;
3677 sb->s_magic = TMPFS_MAGIC;
3678 sb->s_op = &shmem_ops;
3679 sb->s_time_gran = 1;
3680#ifdef CONFIG_TMPFS_XATTR
3681 sb->s_xattr = shmem_xattr_handlers;
3682#endif
3683#ifdef CONFIG_TMPFS_POSIX_ACL
3684 sb->s_flags |= SB_POSIXACL;
3685#endif
3686 uuid_gen(&sb->s_uuid);
3687
3688 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3689 if (!inode)
3690 goto failed;
3691 inode->i_uid = sbinfo->uid;
3692 inode->i_gid = sbinfo->gid;
3693 sb->s_root = d_make_root(inode);
3694 if (!sb->s_root)
3695 goto failed;
3696 return 0;
3697
3698failed:
3699 shmem_put_super(sb);
3700 return err;
3701}
3702
3703static int shmem_get_tree(struct fs_context *fc)
3704{
3705 return get_tree_nodev(fc, shmem_fill_super);
3706}
3707
3708static void shmem_free_fc(struct fs_context *fc)
3709{
3710 struct shmem_options *ctx = fc->fs_private;
3711
3712 if (ctx) {
3713 mpol_put(ctx->mpol);
3714 kfree(ctx);
3715 }
3716}
3717
3718static const struct fs_context_operations shmem_fs_context_ops = {
3719 .free = shmem_free_fc,
3720 .get_tree = shmem_get_tree,
3721#ifdef CONFIG_TMPFS
3722 .parse_monolithic = shmem_parse_options,
3723 .parse_param = shmem_parse_one,
3724 .reconfigure = shmem_reconfigure,
3725#endif
3726};
3727
3728static struct kmem_cache *shmem_inode_cachep;
3729
3730static struct inode *shmem_alloc_inode(struct super_block *sb)
3731{
3732 struct shmem_inode_info *info;
3733 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3734 if (!info)
3735 return NULL;
3736 return &info->vfs_inode;
3737}
3738
3739static void shmem_free_in_core_inode(struct inode *inode)
3740{
3741 if (S_ISLNK(inode->i_mode))
3742 kfree(inode->i_link);
3743 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3744}
3745
3746static void shmem_destroy_inode(struct inode *inode)
3747{
3748 if (S_ISREG(inode->i_mode))
3749 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3750}
3751
3752static void shmem_init_inode(void *foo)
3753{
3754 struct shmem_inode_info *info = foo;
3755 inode_init_once(&info->vfs_inode);
3756}
3757
3758static void shmem_init_inodecache(void)
3759{
3760 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3761 sizeof(struct shmem_inode_info),
3762 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3763}
3764
3765static void shmem_destroy_inodecache(void)
3766{
3767 kmem_cache_destroy(shmem_inode_cachep);
3768}
3769
3770static const struct address_space_operations shmem_aops = {
3771 .writepage = shmem_writepage,
3772 .set_page_dirty = __set_page_dirty_no_writeback,
3773#ifdef CONFIG_TMPFS
3774 .write_begin = shmem_write_begin,
3775 .write_end = shmem_write_end,
3776#endif
3777#ifdef CONFIG_MIGRATION
3778 .migratepage = migrate_page,
3779#endif
3780 .error_remove_page = generic_error_remove_page,
3781};
3782
3783static const struct file_operations shmem_file_operations = {
3784 .mmap = shmem_mmap,
3785 .get_unmapped_area = shmem_get_unmapped_area,
3786#ifdef CONFIG_TMPFS
3787 .llseek = shmem_file_llseek,
3788 .read_iter = shmem_file_read_iter,
3789 .write_iter = generic_file_write_iter,
3790 .fsync = noop_fsync,
3791 .splice_read = generic_file_splice_read,
3792 .splice_write = iter_file_splice_write,
3793 .fallocate = shmem_fallocate,
3794#endif
3795};
3796
3797static const struct inode_operations shmem_inode_operations = {
3798 .getattr = shmem_getattr,
3799 .setattr = shmem_setattr,
3800#ifdef CONFIG_TMPFS_XATTR
3801 .listxattr = shmem_listxattr,
3802 .set_acl = simple_set_acl,
3803#endif
3804};
3805
3806static const struct inode_operations shmem_dir_inode_operations = {
3807#ifdef CONFIG_TMPFS
3808 .create = shmem_create,
3809 .lookup = simple_lookup,
3810 .link = shmem_link,
3811 .unlink = shmem_unlink,
3812 .symlink = shmem_symlink,
3813 .mkdir = shmem_mkdir,
3814 .rmdir = shmem_rmdir,
3815 .mknod = shmem_mknod,
3816 .rename = shmem_rename2,
3817 .tmpfile = shmem_tmpfile,
3818#endif
3819#ifdef CONFIG_TMPFS_XATTR
3820 .listxattr = shmem_listxattr,
3821#endif
3822#ifdef CONFIG_TMPFS_POSIX_ACL
3823 .setattr = shmem_setattr,
3824 .set_acl = simple_set_acl,
3825#endif
3826};
3827
3828static const struct inode_operations shmem_special_inode_operations = {
3829#ifdef CONFIG_TMPFS_XATTR
3830 .listxattr = shmem_listxattr,
3831#endif
3832#ifdef CONFIG_TMPFS_POSIX_ACL
3833 .setattr = shmem_setattr,
3834 .set_acl = simple_set_acl,
3835#endif
3836};
3837
3838static const struct super_operations shmem_ops = {
3839 .alloc_inode = shmem_alloc_inode,
3840 .free_inode = shmem_free_in_core_inode,
3841 .destroy_inode = shmem_destroy_inode,
3842#ifdef CONFIG_TMPFS
3843 .statfs = shmem_statfs,
3844 .show_options = shmem_show_options,
3845#endif
3846 .evict_inode = shmem_evict_inode,
3847 .drop_inode = generic_delete_inode,
3848 .put_super = shmem_put_super,
3849#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3850 .nr_cached_objects = shmem_unused_huge_count,
3851 .free_cached_objects = shmem_unused_huge_scan,
3852#endif
3853};
3854
3855static const struct vm_operations_struct shmem_vm_ops = {
3856 .fault = shmem_fault,
3857 .map_pages = filemap_map_pages,
3858#ifdef CONFIG_NUMA
3859 .set_policy = shmem_set_policy,
3860 .get_policy = shmem_get_policy,
3861#endif
3862};
3863
3864int shmem_init_fs_context(struct fs_context *fc)
3865{
3866 struct shmem_options *ctx;
3867
3868 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
3869 if (!ctx)
3870 return -ENOMEM;
3871
3872 ctx->mode = 0777 | S_ISVTX;
3873 ctx->uid = current_fsuid();
3874 ctx->gid = current_fsgid();
3875
3876 fc->fs_private = ctx;
3877 fc->ops = &shmem_fs_context_ops;
3878 return 0;
3879}
3880
3881static struct file_system_type shmem_fs_type = {
3882 .owner = THIS_MODULE,
3883 .name = "tmpfs",
3884 .init_fs_context = shmem_init_fs_context,
3885#ifdef CONFIG_TMPFS
3886 .parameters = &shmem_fs_parameters,
3887#endif
3888 .kill_sb = kill_litter_super,
3889 .fs_flags = FS_USERNS_MOUNT,
3890};
3891
3892int __init shmem_init(void)
3893{
3894 int error;
3895
3896 shmem_init_inodecache();
3897
3898 error = register_filesystem(&shmem_fs_type);
3899 if (error) {
3900 pr_err("Could not register tmpfs\n");
3901 goto out2;
3902 }
3903
3904 shm_mnt = kern_mount(&shmem_fs_type);
3905 if (IS_ERR(shm_mnt)) {
3906 error = PTR_ERR(shm_mnt);
3907 pr_err("Could not kern_mount tmpfs\n");
3908 goto out1;
3909 }
3910
3911#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3912 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
3913 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3914 else
3915 shmem_huge = 0; /* just in case it was patched */
3916#endif
3917 return 0;
3918
3919out1:
3920 unregister_filesystem(&shmem_fs_type);
3921out2:
3922 shmem_destroy_inodecache();
3923 shm_mnt = ERR_PTR(error);
3924 return error;
3925}
3926
3927#if defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && defined(CONFIG_SYSFS)
3928static ssize_t shmem_enabled_show(struct kobject *kobj,
3929 struct kobj_attribute *attr, char *buf)
3930{
3931 int values[] = {
3932 SHMEM_HUGE_ALWAYS,
3933 SHMEM_HUGE_WITHIN_SIZE,
3934 SHMEM_HUGE_ADVISE,
3935 SHMEM_HUGE_NEVER,
3936 SHMEM_HUGE_DENY,
3937 SHMEM_HUGE_FORCE,
3938 };
3939 int i, count;
3940
3941 for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
3942 const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
3943
3944 count += sprintf(buf + count, fmt,
3945 shmem_format_huge(values[i]));
3946 }
3947 buf[count - 1] = '\n';
3948 return count;
3949}
3950
3951static ssize_t shmem_enabled_store(struct kobject *kobj,
3952 struct kobj_attribute *attr, const char *buf, size_t count)
3953{
3954 char tmp[16];
3955 int huge;
3956
3957 if (count + 1 > sizeof(tmp))
3958 return -EINVAL;
3959 memcpy(tmp, buf, count);
3960 tmp[count] = '\0';
3961 if (count && tmp[count - 1] == '\n')
3962 tmp[count - 1] = '\0';
3963
3964 huge = shmem_parse_huge(tmp);
3965 if (huge == -EINVAL)
3966 return -EINVAL;
3967 if (!has_transparent_hugepage() &&
3968 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
3969 return -EINVAL;
3970
3971 shmem_huge = huge;
3972 if (shmem_huge > SHMEM_HUGE_DENY)
3973 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3974 return count;
3975}
3976
3977struct kobj_attribute shmem_enabled_attr =
3978 __ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
3979#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE && CONFIG_SYSFS */
3980
3981#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3982bool shmem_huge_enabled(struct vm_area_struct *vma)
3983{
3984 struct inode *inode = file_inode(vma->vm_file);
3985 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3986 loff_t i_size;
3987 pgoff_t off;
3988
3989 if ((vma->vm_flags & VM_NOHUGEPAGE) ||
3990 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
3991 return false;
3992 if (shmem_huge == SHMEM_HUGE_FORCE)
3993 return true;
3994 if (shmem_huge == SHMEM_HUGE_DENY)
3995 return false;
3996 switch (sbinfo->huge) {
3997 case SHMEM_HUGE_NEVER:
3998 return false;
3999 case SHMEM_HUGE_ALWAYS:
4000 return true;
4001 case SHMEM_HUGE_WITHIN_SIZE:
4002 off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
4003 i_size = round_up(i_size_read(inode), PAGE_SIZE);
4004 if (i_size >= HPAGE_PMD_SIZE &&
4005 i_size >> PAGE_SHIFT >= off)
4006 return true;
4007 /* fall through */
4008 case SHMEM_HUGE_ADVISE:
4009 /* TODO: implement fadvise() hints */
4010 return (vma->vm_flags & VM_HUGEPAGE);
4011 default:
4012 VM_BUG_ON(1);
4013 return false;
4014 }
4015}
4016#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
4017
4018#else /* !CONFIG_SHMEM */
4019
4020/*
4021 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4022 *
4023 * This is intended for small system where the benefits of the full
4024 * shmem code (swap-backed and resource-limited) are outweighed by
4025 * their complexity. On systems without swap this code should be
4026 * effectively equivalent, but much lighter weight.
4027 */
4028
4029static struct file_system_type shmem_fs_type = {
4030 .name = "tmpfs",
4031 .init_fs_context = ramfs_init_fs_context,
4032 .parameters = &ramfs_fs_parameters,
4033 .kill_sb = kill_litter_super,
4034 .fs_flags = FS_USERNS_MOUNT,
4035};
4036
4037int __init shmem_init(void)
4038{
4039 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4040
4041 shm_mnt = kern_mount(&shmem_fs_type);
4042 BUG_ON(IS_ERR(shm_mnt));
4043
4044 return 0;
4045}
4046
4047int shmem_unuse(unsigned int type, bool frontswap,
4048 unsigned long *fs_pages_to_unuse)
4049{
4050 return 0;
4051}
4052
4053int shmem_lock(struct file *file, int lock, struct user_struct *user)
4054{
4055 return 0;
4056}
4057
4058void shmem_unlock_mapping(struct address_space *mapping)
4059{
4060}
4061
4062#ifdef CONFIG_MMU
4063unsigned long shmem_get_unmapped_area(struct file *file,
4064 unsigned long addr, unsigned long len,
4065 unsigned long pgoff, unsigned long flags)
4066{
4067 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4068}
4069#endif
4070
4071void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4072{
4073 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4074}
4075EXPORT_SYMBOL_GPL(shmem_truncate_range);
4076
4077#define shmem_vm_ops generic_file_vm_ops
4078#define shmem_file_operations ramfs_file_operations
4079#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4080#define shmem_acct_size(flags, size) 0
4081#define shmem_unacct_size(flags, size) do {} while (0)
4082
4083#endif /* CONFIG_SHMEM */
4084
4085/* common code */
4086
4087static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4088 unsigned long flags, unsigned int i_flags)
4089{
4090 struct inode *inode;
4091 struct file *res;
4092
4093 if (IS_ERR(mnt))
4094 return ERR_CAST(mnt);
4095
4096 if (size < 0 || size > MAX_LFS_FILESIZE)
4097 return ERR_PTR(-EINVAL);
4098
4099 if (shmem_acct_size(flags, size))
4100 return ERR_PTR(-ENOMEM);
4101
4102 inode = shmem_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0,
4103 flags);
4104 if (unlikely(!inode)) {
4105 shmem_unacct_size(flags, size);
4106 return ERR_PTR(-ENOSPC);
4107 }
4108 inode->i_flags |= i_flags;
4109 inode->i_size = size;
4110 clear_nlink(inode); /* It is unlinked */
4111 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4112 if (!IS_ERR(res))
4113 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4114 &shmem_file_operations);
4115 if (IS_ERR(res))
4116 iput(inode);
4117 return res;
4118}
4119
4120/**
4121 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4122 * kernel internal. There will be NO LSM permission checks against the
4123 * underlying inode. So users of this interface must do LSM checks at a
4124 * higher layer. The users are the big_key and shm implementations. LSM
4125 * checks are provided at the key or shm level rather than the inode.
4126 * @name: name for dentry (to be seen in /proc/<pid>/maps
4127 * @size: size to be set for the file
4128 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4129 */
4130struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4131{
4132 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4133}
4134
4135/**
4136 * shmem_file_setup - get an unlinked file living in tmpfs
4137 * @name: name for dentry (to be seen in /proc/<pid>/maps
4138 * @size: size to be set for the file
4139 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4140 */
4141struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4142{
4143 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4144}
4145EXPORT_SYMBOL_GPL(shmem_file_setup);
4146
4147/**
4148 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4149 * @mnt: the tmpfs mount where the file will be created
4150 * @name: name for dentry (to be seen in /proc/<pid>/maps
4151 * @size: size to be set for the file
4152 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4153 */
4154struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4155 loff_t size, unsigned long flags)
4156{
4157 return __shmem_file_setup(mnt, name, size, flags, 0);
4158}
4159EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4160
4161/**
4162 * shmem_zero_setup - setup a shared anonymous mapping
4163 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
4164 */
4165int shmem_zero_setup(struct vm_area_struct *vma)
4166{
4167 struct file *file;
4168 loff_t size = vma->vm_end - vma->vm_start;
4169
4170 /*
4171 * Cloning a new file under mmap_sem leads to a lock ordering conflict
4172 * between XFS directory reading and selinux: since this file is only
4173 * accessible to the user through its mapping, use S_PRIVATE flag to
4174 * bypass file security, in the same way as shmem_kernel_file_setup().
4175 */
4176 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4177 if (IS_ERR(file))
4178 return PTR_ERR(file);
4179
4180 if (vma->vm_file)
4181 fput(vma->vm_file);
4182 vma->vm_file = file;
4183 vma->vm_ops = &shmem_vm_ops;
4184
4185 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
4186 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4187 (vma->vm_end & HPAGE_PMD_MASK)) {
4188 khugepaged_enter(vma, vma->vm_flags);
4189 }
4190
4191 return 0;
4192}
4193
4194/**
4195 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4196 * @mapping: the page's address_space
4197 * @index: the page index
4198 * @gfp: the page allocator flags to use if allocating
4199 *
4200 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4201 * with any new page allocations done using the specified allocation flags.
4202 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4203 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4204 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4205 *
4206 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4207 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4208 */
4209struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4210 pgoff_t index, gfp_t gfp)
4211{
4212#ifdef CONFIG_SHMEM
4213 struct inode *inode = mapping->host;
4214 struct page *page;
4215 int error;
4216
4217 BUG_ON(mapping->a_ops != &shmem_aops);
4218 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4219 gfp, NULL, NULL, NULL);
4220 if (error)
4221 page = ERR_PTR(error);
4222 else
4223 unlock_page(page);
4224 return page;
4225#else
4226 /*
4227 * The tiny !SHMEM case uses ramfs without swap
4228 */
4229 return read_cache_page_gfp(mapping, index, gfp);
4230#endif
4231}
4232EXPORT_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/mm.h>
32#include <linux/export.h>
33#include <linux/swap.h>
34#include <linux/aio.h>
35
36static struct vfsmount *shm_mnt;
37
38#ifdef CONFIG_SHMEM
39/*
40 * This virtual memory filesystem is heavily based on the ramfs. It
41 * extends ramfs by the ability to use swap and honor resource limits
42 * which makes it a completely usable filesystem.
43 */
44
45#include <linux/xattr.h>
46#include <linux/exportfs.h>
47#include <linux/posix_acl.h>
48#include <linux/posix_acl_xattr.h>
49#include <linux/mman.h>
50#include <linux/string.h>
51#include <linux/slab.h>
52#include <linux/backing-dev.h>
53#include <linux/shmem_fs.h>
54#include <linux/writeback.h>
55#include <linux/blkdev.h>
56#include <linux/pagevec.h>
57#include <linux/percpu_counter.h>
58#include <linux/falloc.h>
59#include <linux/splice.h>
60#include <linux/security.h>
61#include <linux/swapops.h>
62#include <linux/mempolicy.h>
63#include <linux/namei.h>
64#include <linux/ctype.h>
65#include <linux/migrate.h>
66#include <linux/highmem.h>
67#include <linux/seq_file.h>
68#include <linux/magic.h>
69
70#include <asm/uaccess.h>
71#include <asm/pgtable.h>
72
73#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
74#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
75
76/* Pretend that each entry is of this size in directory's i_size */
77#define BOGO_DIRENT_SIZE 20
78
79/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
80#define SHORT_SYMLINK_LEN 128
81
82/*
83 * shmem_fallocate and shmem_writepage communicate via inode->i_private
84 * (with i_mutex making sure that it has only one user at a time):
85 * we would prefer not to enlarge the shmem inode just for that.
86 */
87struct shmem_falloc {
88 pgoff_t start; /* start of range currently being fallocated */
89 pgoff_t next; /* the next page offset to be fallocated */
90 pgoff_t nr_falloced; /* how many new pages have been fallocated */
91 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
92};
93
94/* Flag allocation requirements to shmem_getpage */
95enum sgp_type {
96 SGP_READ, /* don't exceed i_size, don't allocate page */
97 SGP_CACHE, /* don't exceed i_size, may allocate page */
98 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
99 SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
100 SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
101};
102
103#ifdef CONFIG_TMPFS
104static unsigned long shmem_default_max_blocks(void)
105{
106 return totalram_pages / 2;
107}
108
109static unsigned long shmem_default_max_inodes(void)
110{
111 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
112}
113#endif
114
115static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
116static int shmem_replace_page(struct page **pagep, gfp_t gfp,
117 struct shmem_inode_info *info, pgoff_t index);
118static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
119 struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
120
121static inline int shmem_getpage(struct inode *inode, pgoff_t index,
122 struct page **pagep, enum sgp_type sgp, int *fault_type)
123{
124 return shmem_getpage_gfp(inode, index, pagep, sgp,
125 mapping_gfp_mask(inode->i_mapping), fault_type);
126}
127
128static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
129{
130 return sb->s_fs_info;
131}
132
133/*
134 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
135 * for shared memory and for shared anonymous (/dev/zero) mappings
136 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
137 * consistent with the pre-accounting of private mappings ...
138 */
139static inline int shmem_acct_size(unsigned long flags, loff_t size)
140{
141 return (flags & VM_NORESERVE) ?
142 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
143}
144
145static inline void shmem_unacct_size(unsigned long flags, loff_t size)
146{
147 if (!(flags & VM_NORESERVE))
148 vm_unacct_memory(VM_ACCT(size));
149}
150
151/*
152 * ... whereas tmpfs objects are accounted incrementally as
153 * pages are allocated, in order to allow huge sparse files.
154 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
155 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
156 */
157static inline int shmem_acct_block(unsigned long flags)
158{
159 return (flags & VM_NORESERVE) ?
160 security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
161}
162
163static inline void shmem_unacct_blocks(unsigned long flags, long pages)
164{
165 if (flags & VM_NORESERVE)
166 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
167}
168
169static const struct super_operations shmem_ops;
170static const struct address_space_operations shmem_aops;
171static const struct file_operations shmem_file_operations;
172static const struct inode_operations shmem_inode_operations;
173static const struct inode_operations shmem_dir_inode_operations;
174static const struct inode_operations shmem_special_inode_operations;
175static const struct vm_operations_struct shmem_vm_ops;
176
177static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
178 .ra_pages = 0, /* No readahead */
179 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
180};
181
182static LIST_HEAD(shmem_swaplist);
183static DEFINE_MUTEX(shmem_swaplist_mutex);
184
185static int shmem_reserve_inode(struct super_block *sb)
186{
187 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
188 if (sbinfo->max_inodes) {
189 spin_lock(&sbinfo->stat_lock);
190 if (!sbinfo->free_inodes) {
191 spin_unlock(&sbinfo->stat_lock);
192 return -ENOSPC;
193 }
194 sbinfo->free_inodes--;
195 spin_unlock(&sbinfo->stat_lock);
196 }
197 return 0;
198}
199
200static void shmem_free_inode(struct super_block *sb)
201{
202 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
203 if (sbinfo->max_inodes) {
204 spin_lock(&sbinfo->stat_lock);
205 sbinfo->free_inodes++;
206 spin_unlock(&sbinfo->stat_lock);
207 }
208}
209
210/**
211 * shmem_recalc_inode - recalculate the block usage of an inode
212 * @inode: inode to recalc
213 *
214 * We have to calculate the free blocks since the mm can drop
215 * undirtied hole pages behind our back.
216 *
217 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
218 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
219 *
220 * It has to be called with the spinlock held.
221 */
222static void shmem_recalc_inode(struct inode *inode)
223{
224 struct shmem_inode_info *info = SHMEM_I(inode);
225 long freed;
226
227 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
228 if (freed > 0) {
229 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
230 if (sbinfo->max_blocks)
231 percpu_counter_add(&sbinfo->used_blocks, -freed);
232 info->alloced -= freed;
233 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
234 shmem_unacct_blocks(info->flags, freed);
235 }
236}
237
238/*
239 * Replace item expected in radix tree by a new item, while holding tree lock.
240 */
241static int shmem_radix_tree_replace(struct address_space *mapping,
242 pgoff_t index, void *expected, void *replacement)
243{
244 void **pslot;
245 void *item;
246
247 VM_BUG_ON(!expected);
248 VM_BUG_ON(!replacement);
249 pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
250 if (!pslot)
251 return -ENOENT;
252 item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
253 if (item != expected)
254 return -ENOENT;
255 radix_tree_replace_slot(pslot, replacement);
256 return 0;
257}
258
259/*
260 * Sometimes, before we decide whether to proceed or to fail, we must check
261 * that an entry was not already brought back from swap by a racing thread.
262 *
263 * Checking page is not enough: by the time a SwapCache page is locked, it
264 * might be reused, and again be SwapCache, using the same swap as before.
265 */
266static bool shmem_confirm_swap(struct address_space *mapping,
267 pgoff_t index, swp_entry_t swap)
268{
269 void *item;
270
271 rcu_read_lock();
272 item = radix_tree_lookup(&mapping->page_tree, index);
273 rcu_read_unlock();
274 return item == swp_to_radix_entry(swap);
275}
276
277/*
278 * Like add_to_page_cache_locked, but error if expected item has gone.
279 */
280static int shmem_add_to_page_cache(struct page *page,
281 struct address_space *mapping,
282 pgoff_t index, gfp_t gfp, void *expected)
283{
284 int error;
285
286 VM_BUG_ON_PAGE(!PageLocked(page), page);
287 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
288
289 page_cache_get(page);
290 page->mapping = mapping;
291 page->index = index;
292
293 spin_lock_irq(&mapping->tree_lock);
294 if (!expected)
295 error = radix_tree_insert(&mapping->page_tree, index, page);
296 else
297 error = shmem_radix_tree_replace(mapping, index, expected,
298 page);
299 if (!error) {
300 mapping->nrpages++;
301 __inc_zone_page_state(page, NR_FILE_PAGES);
302 __inc_zone_page_state(page, NR_SHMEM);
303 spin_unlock_irq(&mapping->tree_lock);
304 } else {
305 page->mapping = NULL;
306 spin_unlock_irq(&mapping->tree_lock);
307 page_cache_release(page);
308 }
309 return error;
310}
311
312/*
313 * Like delete_from_page_cache, but substitutes swap for page.
314 */
315static void shmem_delete_from_page_cache(struct page *page, void *radswap)
316{
317 struct address_space *mapping = page->mapping;
318 int error;
319
320 spin_lock_irq(&mapping->tree_lock);
321 error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
322 page->mapping = NULL;
323 mapping->nrpages--;
324 __dec_zone_page_state(page, NR_FILE_PAGES);
325 __dec_zone_page_state(page, NR_SHMEM);
326 spin_unlock_irq(&mapping->tree_lock);
327 page_cache_release(page);
328 BUG_ON(error);
329}
330
331/*
332 * Remove swap entry from radix tree, free the swap and its page cache.
333 */
334static int shmem_free_swap(struct address_space *mapping,
335 pgoff_t index, void *radswap)
336{
337 void *old;
338
339 spin_lock_irq(&mapping->tree_lock);
340 old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
341 spin_unlock_irq(&mapping->tree_lock);
342 if (old != radswap)
343 return -ENOENT;
344 free_swap_and_cache(radix_to_swp_entry(radswap));
345 return 0;
346}
347
348/*
349 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
350 */
351void shmem_unlock_mapping(struct address_space *mapping)
352{
353 struct pagevec pvec;
354 pgoff_t indices[PAGEVEC_SIZE];
355 pgoff_t index = 0;
356
357 pagevec_init(&pvec, 0);
358 /*
359 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
360 */
361 while (!mapping_unevictable(mapping)) {
362 /*
363 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
364 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
365 */
366 pvec.nr = find_get_entries(mapping, index,
367 PAGEVEC_SIZE, pvec.pages, indices);
368 if (!pvec.nr)
369 break;
370 index = indices[pvec.nr - 1] + 1;
371 pagevec_remove_exceptionals(&pvec);
372 check_move_unevictable_pages(pvec.pages, pvec.nr);
373 pagevec_release(&pvec);
374 cond_resched();
375 }
376}
377
378/*
379 * Remove range of pages and swap entries from radix tree, and free them.
380 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
381 */
382static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
383 bool unfalloc)
384{
385 struct address_space *mapping = inode->i_mapping;
386 struct shmem_inode_info *info = SHMEM_I(inode);
387 pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
388 pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
389 unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
390 unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
391 struct pagevec pvec;
392 pgoff_t indices[PAGEVEC_SIZE];
393 long nr_swaps_freed = 0;
394 pgoff_t index;
395 int i;
396
397 if (lend == -1)
398 end = -1; /* unsigned, so actually very big */
399
400 pagevec_init(&pvec, 0);
401 index = start;
402 while (index < end) {
403 pvec.nr = find_get_entries(mapping, index,
404 min(end - index, (pgoff_t)PAGEVEC_SIZE),
405 pvec.pages, indices);
406 if (!pvec.nr)
407 break;
408 mem_cgroup_uncharge_start();
409 for (i = 0; i < pagevec_count(&pvec); i++) {
410 struct page *page = pvec.pages[i];
411
412 index = indices[i];
413 if (index >= end)
414 break;
415
416 if (radix_tree_exceptional_entry(page)) {
417 if (unfalloc)
418 continue;
419 nr_swaps_freed += !shmem_free_swap(mapping,
420 index, page);
421 continue;
422 }
423
424 if (!trylock_page(page))
425 continue;
426 if (!unfalloc || !PageUptodate(page)) {
427 if (page->mapping == mapping) {
428 VM_BUG_ON_PAGE(PageWriteback(page), page);
429 truncate_inode_page(mapping, page);
430 }
431 }
432 unlock_page(page);
433 }
434 pagevec_remove_exceptionals(&pvec);
435 pagevec_release(&pvec);
436 mem_cgroup_uncharge_end();
437 cond_resched();
438 index++;
439 }
440
441 if (partial_start) {
442 struct page *page = NULL;
443 shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
444 if (page) {
445 unsigned int top = PAGE_CACHE_SIZE;
446 if (start > end) {
447 top = partial_end;
448 partial_end = 0;
449 }
450 zero_user_segment(page, partial_start, top);
451 set_page_dirty(page);
452 unlock_page(page);
453 page_cache_release(page);
454 }
455 }
456 if (partial_end) {
457 struct page *page = NULL;
458 shmem_getpage(inode, end, &page, SGP_READ, NULL);
459 if (page) {
460 zero_user_segment(page, 0, partial_end);
461 set_page_dirty(page);
462 unlock_page(page);
463 page_cache_release(page);
464 }
465 }
466 if (start >= end)
467 return;
468
469 index = start;
470 for ( ; ; ) {
471 cond_resched();
472
473 pvec.nr = find_get_entries(mapping, index,
474 min(end - index, (pgoff_t)PAGEVEC_SIZE),
475 pvec.pages, indices);
476 if (!pvec.nr) {
477 if (index == start || unfalloc)
478 break;
479 index = start;
480 continue;
481 }
482 if ((index == start || unfalloc) && indices[0] >= end) {
483 pagevec_remove_exceptionals(&pvec);
484 pagevec_release(&pvec);
485 break;
486 }
487 mem_cgroup_uncharge_start();
488 for (i = 0; i < pagevec_count(&pvec); i++) {
489 struct page *page = pvec.pages[i];
490
491 index = indices[i];
492 if (index >= end)
493 break;
494
495 if (radix_tree_exceptional_entry(page)) {
496 if (unfalloc)
497 continue;
498 nr_swaps_freed += !shmem_free_swap(mapping,
499 index, page);
500 continue;
501 }
502
503 lock_page(page);
504 if (!unfalloc || !PageUptodate(page)) {
505 if (page->mapping == mapping) {
506 VM_BUG_ON_PAGE(PageWriteback(page), page);
507 truncate_inode_page(mapping, page);
508 }
509 }
510 unlock_page(page);
511 }
512 pagevec_remove_exceptionals(&pvec);
513 pagevec_release(&pvec);
514 mem_cgroup_uncharge_end();
515 index++;
516 }
517
518 spin_lock(&info->lock);
519 info->swapped -= nr_swaps_freed;
520 shmem_recalc_inode(inode);
521 spin_unlock(&info->lock);
522}
523
524void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
525{
526 shmem_undo_range(inode, lstart, lend, false);
527 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
528}
529EXPORT_SYMBOL_GPL(shmem_truncate_range);
530
531static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
532{
533 struct inode *inode = dentry->d_inode;
534 int error;
535
536 error = inode_change_ok(inode, attr);
537 if (error)
538 return error;
539
540 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
541 loff_t oldsize = inode->i_size;
542 loff_t newsize = attr->ia_size;
543
544 if (newsize != oldsize) {
545 i_size_write(inode, newsize);
546 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
547 }
548 if (newsize < oldsize) {
549 loff_t holebegin = round_up(newsize, PAGE_SIZE);
550 unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
551 shmem_truncate_range(inode, newsize, (loff_t)-1);
552 /* unmap again to remove racily COWed private pages */
553 unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
554 }
555 }
556
557 setattr_copy(inode, attr);
558 if (attr->ia_valid & ATTR_MODE)
559 error = posix_acl_chmod(inode, inode->i_mode);
560 return error;
561}
562
563static void shmem_evict_inode(struct inode *inode)
564{
565 struct shmem_inode_info *info = SHMEM_I(inode);
566
567 if (inode->i_mapping->a_ops == &shmem_aops) {
568 shmem_unacct_size(info->flags, inode->i_size);
569 inode->i_size = 0;
570 shmem_truncate_range(inode, 0, (loff_t)-1);
571 if (!list_empty(&info->swaplist)) {
572 mutex_lock(&shmem_swaplist_mutex);
573 list_del_init(&info->swaplist);
574 mutex_unlock(&shmem_swaplist_mutex);
575 }
576 } else
577 kfree(info->symlink);
578
579 simple_xattrs_free(&info->xattrs);
580 WARN_ON(inode->i_blocks);
581 shmem_free_inode(inode->i_sb);
582 clear_inode(inode);
583}
584
585/*
586 * If swap found in inode, free it and move page from swapcache to filecache.
587 */
588static int shmem_unuse_inode(struct shmem_inode_info *info,
589 swp_entry_t swap, struct page **pagep)
590{
591 struct address_space *mapping = info->vfs_inode.i_mapping;
592 void *radswap;
593 pgoff_t index;
594 gfp_t gfp;
595 int error = 0;
596
597 radswap = swp_to_radix_entry(swap);
598 index = radix_tree_locate_item(&mapping->page_tree, radswap);
599 if (index == -1)
600 return 0;
601
602 /*
603 * Move _head_ to start search for next from here.
604 * But be careful: shmem_evict_inode checks list_empty without taking
605 * mutex, and there's an instant in list_move_tail when info->swaplist
606 * would appear empty, if it were the only one on shmem_swaplist.
607 */
608 if (shmem_swaplist.next != &info->swaplist)
609 list_move_tail(&shmem_swaplist, &info->swaplist);
610
611 gfp = mapping_gfp_mask(mapping);
612 if (shmem_should_replace_page(*pagep, gfp)) {
613 mutex_unlock(&shmem_swaplist_mutex);
614 error = shmem_replace_page(pagep, gfp, info, index);
615 mutex_lock(&shmem_swaplist_mutex);
616 /*
617 * We needed to drop mutex to make that restrictive page
618 * allocation, but the inode might have been freed while we
619 * dropped it: although a racing shmem_evict_inode() cannot
620 * complete without emptying the radix_tree, our page lock
621 * on this swapcache page is not enough to prevent that -
622 * free_swap_and_cache() of our swap entry will only
623 * trylock_page(), removing swap from radix_tree whatever.
624 *
625 * We must not proceed to shmem_add_to_page_cache() if the
626 * inode has been freed, but of course we cannot rely on
627 * inode or mapping or info to check that. However, we can
628 * safely check if our swap entry is still in use (and here
629 * it can't have got reused for another page): if it's still
630 * in use, then the inode cannot have been freed yet, and we
631 * can safely proceed (if it's no longer in use, that tells
632 * nothing about the inode, but we don't need to unuse swap).
633 */
634 if (!page_swapcount(*pagep))
635 error = -ENOENT;
636 }
637
638 /*
639 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
640 * but also to hold up shmem_evict_inode(): so inode cannot be freed
641 * beneath us (pagelock doesn't help until the page is in pagecache).
642 */
643 if (!error)
644 error = shmem_add_to_page_cache(*pagep, mapping, index,
645 GFP_NOWAIT, radswap);
646 if (error != -ENOMEM) {
647 /*
648 * Truncation and eviction use free_swap_and_cache(), which
649 * only does trylock page: if we raced, best clean up here.
650 */
651 delete_from_swap_cache(*pagep);
652 set_page_dirty(*pagep);
653 if (!error) {
654 spin_lock(&info->lock);
655 info->swapped--;
656 spin_unlock(&info->lock);
657 swap_free(swap);
658 }
659 error = 1; /* not an error, but entry was found */
660 }
661 return error;
662}
663
664/*
665 * Search through swapped inodes to find and replace swap by page.
666 */
667int shmem_unuse(swp_entry_t swap, struct page *page)
668{
669 struct list_head *this, *next;
670 struct shmem_inode_info *info;
671 int found = 0;
672 int error = 0;
673
674 /*
675 * There's a faint possibility that swap page was replaced before
676 * caller locked it: caller will come back later with the right page.
677 */
678 if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
679 goto out;
680
681 /*
682 * Charge page using GFP_KERNEL while we can wait, before taking
683 * the shmem_swaplist_mutex which might hold up shmem_writepage().
684 * Charged back to the user (not to caller) when swap account is used.
685 */
686 error = mem_cgroup_charge_file(page, current->mm, GFP_KERNEL);
687 if (error)
688 goto out;
689 /* No radix_tree_preload: swap entry keeps a place for page in tree */
690
691 mutex_lock(&shmem_swaplist_mutex);
692 list_for_each_safe(this, next, &shmem_swaplist) {
693 info = list_entry(this, struct shmem_inode_info, swaplist);
694 if (info->swapped)
695 found = shmem_unuse_inode(info, swap, &page);
696 else
697 list_del_init(&info->swaplist);
698 cond_resched();
699 if (found)
700 break;
701 }
702 mutex_unlock(&shmem_swaplist_mutex);
703
704 if (found < 0)
705 error = found;
706out:
707 unlock_page(page);
708 page_cache_release(page);
709 return error;
710}
711
712/*
713 * Move the page from the page cache to the swap cache.
714 */
715static int shmem_writepage(struct page *page, struct writeback_control *wbc)
716{
717 struct shmem_inode_info *info;
718 struct address_space *mapping;
719 struct inode *inode;
720 swp_entry_t swap;
721 pgoff_t index;
722
723 BUG_ON(!PageLocked(page));
724 mapping = page->mapping;
725 index = page->index;
726 inode = mapping->host;
727 info = SHMEM_I(inode);
728 if (info->flags & VM_LOCKED)
729 goto redirty;
730 if (!total_swap_pages)
731 goto redirty;
732
733 /*
734 * shmem_backing_dev_info's capabilities prevent regular writeback or
735 * sync from ever calling shmem_writepage; but a stacking filesystem
736 * might use ->writepage of its underlying filesystem, in which case
737 * tmpfs should write out to swap only in response to memory pressure,
738 * and not for the writeback threads or sync.
739 */
740 if (!wbc->for_reclaim) {
741 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
742 goto redirty;
743 }
744
745 /*
746 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
747 * value into swapfile.c, the only way we can correctly account for a
748 * fallocated page arriving here is now to initialize it and write it.
749 *
750 * That's okay for a page already fallocated earlier, but if we have
751 * not yet completed the fallocation, then (a) we want to keep track
752 * of this page in case we have to undo it, and (b) it may not be a
753 * good idea to continue anyway, once we're pushing into swap. So
754 * reactivate the page, and let shmem_fallocate() quit when too many.
755 */
756 if (!PageUptodate(page)) {
757 if (inode->i_private) {
758 struct shmem_falloc *shmem_falloc;
759 spin_lock(&inode->i_lock);
760 shmem_falloc = inode->i_private;
761 if (shmem_falloc &&
762 index >= shmem_falloc->start &&
763 index < shmem_falloc->next)
764 shmem_falloc->nr_unswapped++;
765 else
766 shmem_falloc = NULL;
767 spin_unlock(&inode->i_lock);
768 if (shmem_falloc)
769 goto redirty;
770 }
771 clear_highpage(page);
772 flush_dcache_page(page);
773 SetPageUptodate(page);
774 }
775
776 swap = get_swap_page();
777 if (!swap.val)
778 goto redirty;
779
780 /*
781 * Add inode to shmem_unuse()'s list of swapped-out inodes,
782 * if it's not already there. Do it now before the page is
783 * moved to swap cache, when its pagelock no longer protects
784 * the inode from eviction. But don't unlock the mutex until
785 * we've incremented swapped, because shmem_unuse_inode() will
786 * prune a !swapped inode from the swaplist under this mutex.
787 */
788 mutex_lock(&shmem_swaplist_mutex);
789 if (list_empty(&info->swaplist))
790 list_add_tail(&info->swaplist, &shmem_swaplist);
791
792 if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
793 swap_shmem_alloc(swap);
794 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
795
796 spin_lock(&info->lock);
797 info->swapped++;
798 shmem_recalc_inode(inode);
799 spin_unlock(&info->lock);
800
801 mutex_unlock(&shmem_swaplist_mutex);
802 BUG_ON(page_mapped(page));
803 swap_writepage(page, wbc);
804 return 0;
805 }
806
807 mutex_unlock(&shmem_swaplist_mutex);
808 swapcache_free(swap, NULL);
809redirty:
810 set_page_dirty(page);
811 if (wbc->for_reclaim)
812 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
813 unlock_page(page);
814 return 0;
815}
816
817#ifdef CONFIG_NUMA
818#ifdef CONFIG_TMPFS
819static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
820{
821 char buffer[64];
822
823 if (!mpol || mpol->mode == MPOL_DEFAULT)
824 return; /* show nothing */
825
826 mpol_to_str(buffer, sizeof(buffer), mpol);
827
828 seq_printf(seq, ",mpol=%s", buffer);
829}
830
831static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
832{
833 struct mempolicy *mpol = NULL;
834 if (sbinfo->mpol) {
835 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
836 mpol = sbinfo->mpol;
837 mpol_get(mpol);
838 spin_unlock(&sbinfo->stat_lock);
839 }
840 return mpol;
841}
842#endif /* CONFIG_TMPFS */
843
844static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
845 struct shmem_inode_info *info, pgoff_t index)
846{
847 struct vm_area_struct pvma;
848 struct page *page;
849
850 /* Create a pseudo vma that just contains the policy */
851 pvma.vm_start = 0;
852 /* Bias interleave by inode number to distribute better across nodes */
853 pvma.vm_pgoff = index + info->vfs_inode.i_ino;
854 pvma.vm_ops = NULL;
855 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
856
857 page = swapin_readahead(swap, gfp, &pvma, 0);
858
859 /* Drop reference taken by mpol_shared_policy_lookup() */
860 mpol_cond_put(pvma.vm_policy);
861
862 return page;
863}
864
865static struct page *shmem_alloc_page(gfp_t gfp,
866 struct shmem_inode_info *info, pgoff_t index)
867{
868 struct vm_area_struct pvma;
869 struct page *page;
870
871 /* Create a pseudo vma that just contains the policy */
872 pvma.vm_start = 0;
873 /* Bias interleave by inode number to distribute better across nodes */
874 pvma.vm_pgoff = index + info->vfs_inode.i_ino;
875 pvma.vm_ops = NULL;
876 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
877
878 page = alloc_page_vma(gfp, &pvma, 0);
879
880 /* Drop reference taken by mpol_shared_policy_lookup() */
881 mpol_cond_put(pvma.vm_policy);
882
883 return page;
884}
885#else /* !CONFIG_NUMA */
886#ifdef CONFIG_TMPFS
887static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
888{
889}
890#endif /* CONFIG_TMPFS */
891
892static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
893 struct shmem_inode_info *info, pgoff_t index)
894{
895 return swapin_readahead(swap, gfp, NULL, 0);
896}
897
898static inline struct page *shmem_alloc_page(gfp_t gfp,
899 struct shmem_inode_info *info, pgoff_t index)
900{
901 return alloc_page(gfp);
902}
903#endif /* CONFIG_NUMA */
904
905#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
906static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
907{
908 return NULL;
909}
910#endif
911
912/*
913 * When a page is moved from swapcache to shmem filecache (either by the
914 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
915 * shmem_unuse_inode()), it may have been read in earlier from swap, in
916 * ignorance of the mapping it belongs to. If that mapping has special
917 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
918 * we may need to copy to a suitable page before moving to filecache.
919 *
920 * In a future release, this may well be extended to respect cpuset and
921 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
922 * but for now it is a simple matter of zone.
923 */
924static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
925{
926 return page_zonenum(page) > gfp_zone(gfp);
927}
928
929static int shmem_replace_page(struct page **pagep, gfp_t gfp,
930 struct shmem_inode_info *info, pgoff_t index)
931{
932 struct page *oldpage, *newpage;
933 struct address_space *swap_mapping;
934 pgoff_t swap_index;
935 int error;
936
937 oldpage = *pagep;
938 swap_index = page_private(oldpage);
939 swap_mapping = page_mapping(oldpage);
940
941 /*
942 * We have arrived here because our zones are constrained, so don't
943 * limit chance of success by further cpuset and node constraints.
944 */
945 gfp &= ~GFP_CONSTRAINT_MASK;
946 newpage = shmem_alloc_page(gfp, info, index);
947 if (!newpage)
948 return -ENOMEM;
949
950 page_cache_get(newpage);
951 copy_highpage(newpage, oldpage);
952 flush_dcache_page(newpage);
953
954 __set_page_locked(newpage);
955 SetPageUptodate(newpage);
956 SetPageSwapBacked(newpage);
957 set_page_private(newpage, swap_index);
958 SetPageSwapCache(newpage);
959
960 /*
961 * Our caller will very soon move newpage out of swapcache, but it's
962 * a nice clean interface for us to replace oldpage by newpage there.
963 */
964 spin_lock_irq(&swap_mapping->tree_lock);
965 error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
966 newpage);
967 if (!error) {
968 __inc_zone_page_state(newpage, NR_FILE_PAGES);
969 __dec_zone_page_state(oldpage, NR_FILE_PAGES);
970 }
971 spin_unlock_irq(&swap_mapping->tree_lock);
972
973 if (unlikely(error)) {
974 /*
975 * Is this possible? I think not, now that our callers check
976 * both PageSwapCache and page_private after getting page lock;
977 * but be defensive. Reverse old to newpage for clear and free.
978 */
979 oldpage = newpage;
980 } else {
981 mem_cgroup_replace_page_cache(oldpage, newpage);
982 lru_cache_add_anon(newpage);
983 *pagep = newpage;
984 }
985
986 ClearPageSwapCache(oldpage);
987 set_page_private(oldpage, 0);
988
989 unlock_page(oldpage);
990 page_cache_release(oldpage);
991 page_cache_release(oldpage);
992 return error;
993}
994
995/*
996 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
997 *
998 * If we allocate a new one we do not mark it dirty. That's up to the
999 * vm. If we swap it in we mark it dirty since we also free the swap
1000 * entry since a page cannot live in both the swap and page cache
1001 */
1002static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1003 struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
1004{
1005 struct address_space *mapping = inode->i_mapping;
1006 struct shmem_inode_info *info;
1007 struct shmem_sb_info *sbinfo;
1008 struct page *page;
1009 swp_entry_t swap;
1010 int error;
1011 int once = 0;
1012 int alloced = 0;
1013
1014 if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
1015 return -EFBIG;
1016repeat:
1017 swap.val = 0;
1018 page = find_lock_entry(mapping, index);
1019 if (radix_tree_exceptional_entry(page)) {
1020 swap = radix_to_swp_entry(page);
1021 page = NULL;
1022 }
1023
1024 if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1025 ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1026 error = -EINVAL;
1027 goto failed;
1028 }
1029
1030 /* fallocated page? */
1031 if (page && !PageUptodate(page)) {
1032 if (sgp != SGP_READ)
1033 goto clear;
1034 unlock_page(page);
1035 page_cache_release(page);
1036 page = NULL;
1037 }
1038 if (page || (sgp == SGP_READ && !swap.val)) {
1039 *pagep = page;
1040 return 0;
1041 }
1042
1043 /*
1044 * Fast cache lookup did not find it:
1045 * bring it back from swap or allocate.
1046 */
1047 info = SHMEM_I(inode);
1048 sbinfo = SHMEM_SB(inode->i_sb);
1049
1050 if (swap.val) {
1051 /* Look it up and read it in.. */
1052 page = lookup_swap_cache(swap);
1053 if (!page) {
1054 /* here we actually do the io */
1055 if (fault_type)
1056 *fault_type |= VM_FAULT_MAJOR;
1057 page = shmem_swapin(swap, gfp, info, index);
1058 if (!page) {
1059 error = -ENOMEM;
1060 goto failed;
1061 }
1062 }
1063
1064 /* We have to do this with page locked to prevent races */
1065 lock_page(page);
1066 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1067 !shmem_confirm_swap(mapping, index, swap)) {
1068 error = -EEXIST; /* try again */
1069 goto unlock;
1070 }
1071 if (!PageUptodate(page)) {
1072 error = -EIO;
1073 goto failed;
1074 }
1075 wait_on_page_writeback(page);
1076
1077 if (shmem_should_replace_page(page, gfp)) {
1078 error = shmem_replace_page(&page, gfp, info, index);
1079 if (error)
1080 goto failed;
1081 }
1082
1083 error = mem_cgroup_charge_file(page, current->mm,
1084 gfp & GFP_RECLAIM_MASK);
1085 if (!error) {
1086 error = shmem_add_to_page_cache(page, mapping, index,
1087 gfp, swp_to_radix_entry(swap));
1088 /*
1089 * We already confirmed swap under page lock, and make
1090 * no memory allocation here, so usually no possibility
1091 * of error; but free_swap_and_cache() only trylocks a
1092 * page, so it is just possible that the entry has been
1093 * truncated or holepunched since swap was confirmed.
1094 * shmem_undo_range() will have done some of the
1095 * unaccounting, now delete_from_swap_cache() will do
1096 * the rest (including mem_cgroup_uncharge_swapcache).
1097 * Reset swap.val? No, leave it so "failed" goes back to
1098 * "repeat": reading a hole and writing should succeed.
1099 */
1100 if (error)
1101 delete_from_swap_cache(page);
1102 }
1103 if (error)
1104 goto failed;
1105
1106 spin_lock(&info->lock);
1107 info->swapped--;
1108 shmem_recalc_inode(inode);
1109 spin_unlock(&info->lock);
1110
1111 delete_from_swap_cache(page);
1112 set_page_dirty(page);
1113 swap_free(swap);
1114
1115 } else {
1116 if (shmem_acct_block(info->flags)) {
1117 error = -ENOSPC;
1118 goto failed;
1119 }
1120 if (sbinfo->max_blocks) {
1121 if (percpu_counter_compare(&sbinfo->used_blocks,
1122 sbinfo->max_blocks) >= 0) {
1123 error = -ENOSPC;
1124 goto unacct;
1125 }
1126 percpu_counter_inc(&sbinfo->used_blocks);
1127 }
1128
1129 page = shmem_alloc_page(gfp, info, index);
1130 if (!page) {
1131 error = -ENOMEM;
1132 goto decused;
1133 }
1134
1135 SetPageSwapBacked(page);
1136 __set_page_locked(page);
1137 error = mem_cgroup_charge_file(page, current->mm,
1138 gfp & GFP_RECLAIM_MASK);
1139 if (error)
1140 goto decused;
1141 error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
1142 if (!error) {
1143 error = shmem_add_to_page_cache(page, mapping, index,
1144 gfp, NULL);
1145 radix_tree_preload_end();
1146 }
1147 if (error) {
1148 mem_cgroup_uncharge_cache_page(page);
1149 goto decused;
1150 }
1151 lru_cache_add_anon(page);
1152
1153 spin_lock(&info->lock);
1154 info->alloced++;
1155 inode->i_blocks += BLOCKS_PER_PAGE;
1156 shmem_recalc_inode(inode);
1157 spin_unlock(&info->lock);
1158 alloced = true;
1159
1160 /*
1161 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1162 */
1163 if (sgp == SGP_FALLOC)
1164 sgp = SGP_WRITE;
1165clear:
1166 /*
1167 * Let SGP_WRITE caller clear ends if write does not fill page;
1168 * but SGP_FALLOC on a page fallocated earlier must initialize
1169 * it now, lest undo on failure cancel our earlier guarantee.
1170 */
1171 if (sgp != SGP_WRITE) {
1172 clear_highpage(page);
1173 flush_dcache_page(page);
1174 SetPageUptodate(page);
1175 }
1176 if (sgp == SGP_DIRTY)
1177 set_page_dirty(page);
1178 }
1179
1180 /* Perhaps the file has been truncated since we checked */
1181 if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1182 ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1183 error = -EINVAL;
1184 if (alloced)
1185 goto trunc;
1186 else
1187 goto failed;
1188 }
1189 *pagep = page;
1190 return 0;
1191
1192 /*
1193 * Error recovery.
1194 */
1195trunc:
1196 info = SHMEM_I(inode);
1197 ClearPageDirty(page);
1198 delete_from_page_cache(page);
1199 spin_lock(&info->lock);
1200 info->alloced--;
1201 inode->i_blocks -= BLOCKS_PER_PAGE;
1202 spin_unlock(&info->lock);
1203decused:
1204 sbinfo = SHMEM_SB(inode->i_sb);
1205 if (sbinfo->max_blocks)
1206 percpu_counter_add(&sbinfo->used_blocks, -1);
1207unacct:
1208 shmem_unacct_blocks(info->flags, 1);
1209failed:
1210 if (swap.val && error != -EINVAL &&
1211 !shmem_confirm_swap(mapping, index, swap))
1212 error = -EEXIST;
1213unlock:
1214 if (page) {
1215 unlock_page(page);
1216 page_cache_release(page);
1217 }
1218 if (error == -ENOSPC && !once++) {
1219 info = SHMEM_I(inode);
1220 spin_lock(&info->lock);
1221 shmem_recalc_inode(inode);
1222 spin_unlock(&info->lock);
1223 goto repeat;
1224 }
1225 if (error == -EEXIST) /* from above or from radix_tree_insert */
1226 goto repeat;
1227 return error;
1228}
1229
1230static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1231{
1232 struct inode *inode = file_inode(vma->vm_file);
1233 int error;
1234 int ret = VM_FAULT_LOCKED;
1235
1236 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1237 if (error)
1238 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1239
1240 if (ret & VM_FAULT_MAJOR) {
1241 count_vm_event(PGMAJFAULT);
1242 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
1243 }
1244 return ret;
1245}
1246
1247#ifdef CONFIG_NUMA
1248static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
1249{
1250 struct inode *inode = file_inode(vma->vm_file);
1251 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
1252}
1253
1254static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1255 unsigned long addr)
1256{
1257 struct inode *inode = file_inode(vma->vm_file);
1258 pgoff_t index;
1259
1260 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1261 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
1262}
1263#endif
1264
1265int shmem_lock(struct file *file, int lock, struct user_struct *user)
1266{
1267 struct inode *inode = file_inode(file);
1268 struct shmem_inode_info *info = SHMEM_I(inode);
1269 int retval = -ENOMEM;
1270
1271 spin_lock(&info->lock);
1272 if (lock && !(info->flags & VM_LOCKED)) {
1273 if (!user_shm_lock(inode->i_size, user))
1274 goto out_nomem;
1275 info->flags |= VM_LOCKED;
1276 mapping_set_unevictable(file->f_mapping);
1277 }
1278 if (!lock && (info->flags & VM_LOCKED) && user) {
1279 user_shm_unlock(inode->i_size, user);
1280 info->flags &= ~VM_LOCKED;
1281 mapping_clear_unevictable(file->f_mapping);
1282 }
1283 retval = 0;
1284
1285out_nomem:
1286 spin_unlock(&info->lock);
1287 return retval;
1288}
1289
1290static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1291{
1292 file_accessed(file);
1293 vma->vm_ops = &shmem_vm_ops;
1294 return 0;
1295}
1296
1297static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1298 umode_t mode, dev_t dev, unsigned long flags)
1299{
1300 struct inode *inode;
1301 struct shmem_inode_info *info;
1302 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1303
1304 if (shmem_reserve_inode(sb))
1305 return NULL;
1306
1307 inode = new_inode(sb);
1308 if (inode) {
1309 inode->i_ino = get_next_ino();
1310 inode_init_owner(inode, dir, mode);
1311 inode->i_blocks = 0;
1312 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1313 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1314 inode->i_generation = get_seconds();
1315 info = SHMEM_I(inode);
1316 memset(info, 0, (char *)inode - (char *)info);
1317 spin_lock_init(&info->lock);
1318 info->flags = flags & VM_NORESERVE;
1319 INIT_LIST_HEAD(&info->swaplist);
1320 simple_xattrs_init(&info->xattrs);
1321 cache_no_acl(inode);
1322
1323 switch (mode & S_IFMT) {
1324 default:
1325 inode->i_op = &shmem_special_inode_operations;
1326 init_special_inode(inode, mode, dev);
1327 break;
1328 case S_IFREG:
1329 inode->i_mapping->a_ops = &shmem_aops;
1330 inode->i_op = &shmem_inode_operations;
1331 inode->i_fop = &shmem_file_operations;
1332 mpol_shared_policy_init(&info->policy,
1333 shmem_get_sbmpol(sbinfo));
1334 break;
1335 case S_IFDIR:
1336 inc_nlink(inode);
1337 /* Some things misbehave if size == 0 on a directory */
1338 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1339 inode->i_op = &shmem_dir_inode_operations;
1340 inode->i_fop = &simple_dir_operations;
1341 break;
1342 case S_IFLNK:
1343 /*
1344 * Must not load anything in the rbtree,
1345 * mpol_free_shared_policy will not be called.
1346 */
1347 mpol_shared_policy_init(&info->policy, NULL);
1348 break;
1349 }
1350 } else
1351 shmem_free_inode(sb);
1352 return inode;
1353}
1354
1355bool shmem_mapping(struct address_space *mapping)
1356{
1357 return mapping->backing_dev_info == &shmem_backing_dev_info;
1358}
1359
1360#ifdef CONFIG_TMPFS
1361static const struct inode_operations shmem_symlink_inode_operations;
1362static const struct inode_operations shmem_short_symlink_operations;
1363
1364#ifdef CONFIG_TMPFS_XATTR
1365static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
1366#else
1367#define shmem_initxattrs NULL
1368#endif
1369
1370static int
1371shmem_write_begin(struct file *file, struct address_space *mapping,
1372 loff_t pos, unsigned len, unsigned flags,
1373 struct page **pagep, void **fsdata)
1374{
1375 struct inode *inode = mapping->host;
1376 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1377 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1378}
1379
1380static int
1381shmem_write_end(struct file *file, struct address_space *mapping,
1382 loff_t pos, unsigned len, unsigned copied,
1383 struct page *page, void *fsdata)
1384{
1385 struct inode *inode = mapping->host;
1386
1387 if (pos + copied > inode->i_size)
1388 i_size_write(inode, pos + copied);
1389
1390 if (!PageUptodate(page)) {
1391 if (copied < PAGE_CACHE_SIZE) {
1392 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1393 zero_user_segments(page, 0, from,
1394 from + copied, PAGE_CACHE_SIZE);
1395 }
1396 SetPageUptodate(page);
1397 }
1398 set_page_dirty(page);
1399 unlock_page(page);
1400 page_cache_release(page);
1401
1402 return copied;
1403}
1404
1405static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1406 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1407{
1408 struct file *file = iocb->ki_filp;
1409 struct inode *inode = file_inode(file);
1410 struct address_space *mapping = inode->i_mapping;
1411 pgoff_t index;
1412 unsigned long offset;
1413 enum sgp_type sgp = SGP_READ;
1414 int error = 0;
1415 ssize_t retval;
1416 size_t count;
1417 loff_t *ppos = &iocb->ki_pos;
1418 struct iov_iter iter;
1419
1420 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1421 if (retval)
1422 return retval;
1423 iov_iter_init(&iter, iov, nr_segs, count, 0);
1424
1425 /*
1426 * Might this read be for a stacking filesystem? Then when reading
1427 * holes of a sparse file, we actually need to allocate those pages,
1428 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1429 */
1430 if (segment_eq(get_fs(), KERNEL_DS))
1431 sgp = SGP_DIRTY;
1432
1433 index = *ppos >> PAGE_CACHE_SHIFT;
1434 offset = *ppos & ~PAGE_CACHE_MASK;
1435
1436 for (;;) {
1437 struct page *page = NULL;
1438 pgoff_t end_index;
1439 unsigned long nr, ret;
1440 loff_t i_size = i_size_read(inode);
1441
1442 end_index = i_size >> PAGE_CACHE_SHIFT;
1443 if (index > end_index)
1444 break;
1445 if (index == end_index) {
1446 nr = i_size & ~PAGE_CACHE_MASK;
1447 if (nr <= offset)
1448 break;
1449 }
1450
1451 error = shmem_getpage(inode, index, &page, sgp, NULL);
1452 if (error) {
1453 if (error == -EINVAL)
1454 error = 0;
1455 break;
1456 }
1457 if (page)
1458 unlock_page(page);
1459
1460 /*
1461 * We must evaluate after, since reads (unlike writes)
1462 * are called without i_mutex protection against truncate
1463 */
1464 nr = PAGE_CACHE_SIZE;
1465 i_size = i_size_read(inode);
1466 end_index = i_size >> PAGE_CACHE_SHIFT;
1467 if (index == end_index) {
1468 nr = i_size & ~PAGE_CACHE_MASK;
1469 if (nr <= offset) {
1470 if (page)
1471 page_cache_release(page);
1472 break;
1473 }
1474 }
1475 nr -= offset;
1476
1477 if (page) {
1478 /*
1479 * If users can be writing to this page using arbitrary
1480 * virtual addresses, take care about potential aliasing
1481 * before reading the page on the kernel side.
1482 */
1483 if (mapping_writably_mapped(mapping))
1484 flush_dcache_page(page);
1485 /*
1486 * Mark the page accessed if we read the beginning.
1487 */
1488 if (!offset)
1489 mark_page_accessed(page);
1490 } else {
1491 page = ZERO_PAGE(0);
1492 page_cache_get(page);
1493 }
1494
1495 /*
1496 * Ok, we have the page, and it's up-to-date, so
1497 * now we can copy it to user space...
1498 */
1499 ret = copy_page_to_iter(page, offset, nr, &iter);
1500 retval += ret;
1501 offset += ret;
1502 index += offset >> PAGE_CACHE_SHIFT;
1503 offset &= ~PAGE_CACHE_MASK;
1504
1505 page_cache_release(page);
1506 if (!iov_iter_count(&iter))
1507 break;
1508 if (ret < nr) {
1509 error = -EFAULT;
1510 break;
1511 }
1512 cond_resched();
1513 }
1514
1515 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1516 file_accessed(file);
1517 return retval ? retval : error;
1518}
1519
1520static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
1521 struct pipe_inode_info *pipe, size_t len,
1522 unsigned int flags)
1523{
1524 struct address_space *mapping = in->f_mapping;
1525 struct inode *inode = mapping->host;
1526 unsigned int loff, nr_pages, req_pages;
1527 struct page *pages[PIPE_DEF_BUFFERS];
1528 struct partial_page partial[PIPE_DEF_BUFFERS];
1529 struct page *page;
1530 pgoff_t index, end_index;
1531 loff_t isize, left;
1532 int error, page_nr;
1533 struct splice_pipe_desc spd = {
1534 .pages = pages,
1535 .partial = partial,
1536 .nr_pages_max = PIPE_DEF_BUFFERS,
1537 .flags = flags,
1538 .ops = &page_cache_pipe_buf_ops,
1539 .spd_release = spd_release_page,
1540 };
1541
1542 isize = i_size_read(inode);
1543 if (unlikely(*ppos >= isize))
1544 return 0;
1545
1546 left = isize - *ppos;
1547 if (unlikely(left < len))
1548 len = left;
1549
1550 if (splice_grow_spd(pipe, &spd))
1551 return -ENOMEM;
1552
1553 index = *ppos >> PAGE_CACHE_SHIFT;
1554 loff = *ppos & ~PAGE_CACHE_MASK;
1555 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1556 nr_pages = min(req_pages, spd.nr_pages_max);
1557
1558 spd.nr_pages = find_get_pages_contig(mapping, index,
1559 nr_pages, spd.pages);
1560 index += spd.nr_pages;
1561 error = 0;
1562
1563 while (spd.nr_pages < nr_pages) {
1564 error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
1565 if (error)
1566 break;
1567 unlock_page(page);
1568 spd.pages[spd.nr_pages++] = page;
1569 index++;
1570 }
1571
1572 index = *ppos >> PAGE_CACHE_SHIFT;
1573 nr_pages = spd.nr_pages;
1574 spd.nr_pages = 0;
1575
1576 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
1577 unsigned int this_len;
1578
1579 if (!len)
1580 break;
1581
1582 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
1583 page = spd.pages[page_nr];
1584
1585 if (!PageUptodate(page) || page->mapping != mapping) {
1586 error = shmem_getpage(inode, index, &page,
1587 SGP_CACHE, NULL);
1588 if (error)
1589 break;
1590 unlock_page(page);
1591 page_cache_release(spd.pages[page_nr]);
1592 spd.pages[page_nr] = page;
1593 }
1594
1595 isize = i_size_read(inode);
1596 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1597 if (unlikely(!isize || index > end_index))
1598 break;
1599
1600 if (end_index == index) {
1601 unsigned int plen;
1602
1603 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1604 if (plen <= loff)
1605 break;
1606
1607 this_len = min(this_len, plen - loff);
1608 len = this_len;
1609 }
1610
1611 spd.partial[page_nr].offset = loff;
1612 spd.partial[page_nr].len = this_len;
1613 len -= this_len;
1614 loff = 0;
1615 spd.nr_pages++;
1616 index++;
1617 }
1618
1619 while (page_nr < nr_pages)
1620 page_cache_release(spd.pages[page_nr++]);
1621
1622 if (spd.nr_pages)
1623 error = splice_to_pipe(pipe, &spd);
1624
1625 splice_shrink_spd(&spd);
1626
1627 if (error > 0) {
1628 *ppos += error;
1629 file_accessed(in);
1630 }
1631 return error;
1632}
1633
1634/*
1635 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
1636 */
1637static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
1638 pgoff_t index, pgoff_t end, int whence)
1639{
1640 struct page *page;
1641 struct pagevec pvec;
1642 pgoff_t indices[PAGEVEC_SIZE];
1643 bool done = false;
1644 int i;
1645
1646 pagevec_init(&pvec, 0);
1647 pvec.nr = 1; /* start small: we may be there already */
1648 while (!done) {
1649 pvec.nr = find_get_entries(mapping, index,
1650 pvec.nr, pvec.pages, indices);
1651 if (!pvec.nr) {
1652 if (whence == SEEK_DATA)
1653 index = end;
1654 break;
1655 }
1656 for (i = 0; i < pvec.nr; i++, index++) {
1657 if (index < indices[i]) {
1658 if (whence == SEEK_HOLE) {
1659 done = true;
1660 break;
1661 }
1662 index = indices[i];
1663 }
1664 page = pvec.pages[i];
1665 if (page && !radix_tree_exceptional_entry(page)) {
1666 if (!PageUptodate(page))
1667 page = NULL;
1668 }
1669 if (index >= end ||
1670 (page && whence == SEEK_DATA) ||
1671 (!page && whence == SEEK_HOLE)) {
1672 done = true;
1673 break;
1674 }
1675 }
1676 pagevec_remove_exceptionals(&pvec);
1677 pagevec_release(&pvec);
1678 pvec.nr = PAGEVEC_SIZE;
1679 cond_resched();
1680 }
1681 return index;
1682}
1683
1684static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
1685{
1686 struct address_space *mapping = file->f_mapping;
1687 struct inode *inode = mapping->host;
1688 pgoff_t start, end;
1689 loff_t new_offset;
1690
1691 if (whence != SEEK_DATA && whence != SEEK_HOLE)
1692 return generic_file_llseek_size(file, offset, whence,
1693 MAX_LFS_FILESIZE, i_size_read(inode));
1694 mutex_lock(&inode->i_mutex);
1695 /* We're holding i_mutex so we can access i_size directly */
1696
1697 if (offset < 0)
1698 offset = -EINVAL;
1699 else if (offset >= inode->i_size)
1700 offset = -ENXIO;
1701 else {
1702 start = offset >> PAGE_CACHE_SHIFT;
1703 end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1704 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
1705 new_offset <<= PAGE_CACHE_SHIFT;
1706 if (new_offset > offset) {
1707 if (new_offset < inode->i_size)
1708 offset = new_offset;
1709 else if (whence == SEEK_DATA)
1710 offset = -ENXIO;
1711 else
1712 offset = inode->i_size;
1713 }
1714 }
1715
1716 if (offset >= 0)
1717 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
1718 mutex_unlock(&inode->i_mutex);
1719 return offset;
1720}
1721
1722static long shmem_fallocate(struct file *file, int mode, loff_t offset,
1723 loff_t len)
1724{
1725 struct inode *inode = file_inode(file);
1726 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1727 struct shmem_falloc shmem_falloc;
1728 pgoff_t start, index, end;
1729 int error;
1730
1731 mutex_lock(&inode->i_mutex);
1732
1733 if (mode & FALLOC_FL_PUNCH_HOLE) {
1734 struct address_space *mapping = file->f_mapping;
1735 loff_t unmap_start = round_up(offset, PAGE_SIZE);
1736 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
1737
1738 if ((u64)unmap_end > (u64)unmap_start)
1739 unmap_mapping_range(mapping, unmap_start,
1740 1 + unmap_end - unmap_start, 0);
1741 shmem_truncate_range(inode, offset, offset + len - 1);
1742 /* No need to unmap again: hole-punching leaves COWed pages */
1743 error = 0;
1744 goto out;
1745 }
1746
1747 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1748 error = inode_newsize_ok(inode, offset + len);
1749 if (error)
1750 goto out;
1751
1752 start = offset >> PAGE_CACHE_SHIFT;
1753 end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1754 /* Try to avoid a swapstorm if len is impossible to satisfy */
1755 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
1756 error = -ENOSPC;
1757 goto out;
1758 }
1759
1760 shmem_falloc.start = start;
1761 shmem_falloc.next = start;
1762 shmem_falloc.nr_falloced = 0;
1763 shmem_falloc.nr_unswapped = 0;
1764 spin_lock(&inode->i_lock);
1765 inode->i_private = &shmem_falloc;
1766 spin_unlock(&inode->i_lock);
1767
1768 for (index = start; index < end; index++) {
1769 struct page *page;
1770
1771 /*
1772 * Good, the fallocate(2) manpage permits EINTR: we may have
1773 * been interrupted because we are using up too much memory.
1774 */
1775 if (signal_pending(current))
1776 error = -EINTR;
1777 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
1778 error = -ENOMEM;
1779 else
1780 error = shmem_getpage(inode, index, &page, SGP_FALLOC,
1781 NULL);
1782 if (error) {
1783 /* Remove the !PageUptodate pages we added */
1784 shmem_undo_range(inode,
1785 (loff_t)start << PAGE_CACHE_SHIFT,
1786 (loff_t)index << PAGE_CACHE_SHIFT, true);
1787 goto undone;
1788 }
1789
1790 /*
1791 * Inform shmem_writepage() how far we have reached.
1792 * No need for lock or barrier: we have the page lock.
1793 */
1794 shmem_falloc.next++;
1795 if (!PageUptodate(page))
1796 shmem_falloc.nr_falloced++;
1797
1798 /*
1799 * If !PageUptodate, leave it that way so that freeable pages
1800 * can be recognized if we need to rollback on error later.
1801 * But set_page_dirty so that memory pressure will swap rather
1802 * than free the pages we are allocating (and SGP_CACHE pages
1803 * might still be clean: we now need to mark those dirty too).
1804 */
1805 set_page_dirty(page);
1806 unlock_page(page);
1807 page_cache_release(page);
1808 cond_resched();
1809 }
1810
1811 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
1812 i_size_write(inode, offset + len);
1813 inode->i_ctime = CURRENT_TIME;
1814undone:
1815 spin_lock(&inode->i_lock);
1816 inode->i_private = NULL;
1817 spin_unlock(&inode->i_lock);
1818out:
1819 mutex_unlock(&inode->i_mutex);
1820 return error;
1821}
1822
1823static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1824{
1825 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1826
1827 buf->f_type = TMPFS_MAGIC;
1828 buf->f_bsize = PAGE_CACHE_SIZE;
1829 buf->f_namelen = NAME_MAX;
1830 if (sbinfo->max_blocks) {
1831 buf->f_blocks = sbinfo->max_blocks;
1832 buf->f_bavail =
1833 buf->f_bfree = sbinfo->max_blocks -
1834 percpu_counter_sum(&sbinfo->used_blocks);
1835 }
1836 if (sbinfo->max_inodes) {
1837 buf->f_files = sbinfo->max_inodes;
1838 buf->f_ffree = sbinfo->free_inodes;
1839 }
1840 /* else leave those fields 0 like simple_statfs */
1841 return 0;
1842}
1843
1844/*
1845 * File creation. Allocate an inode, and we're done..
1846 */
1847static int
1848shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
1849{
1850 struct inode *inode;
1851 int error = -ENOSPC;
1852
1853 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
1854 if (inode) {
1855 error = simple_acl_create(dir, inode);
1856 if (error)
1857 goto out_iput;
1858 error = security_inode_init_security(inode, dir,
1859 &dentry->d_name,
1860 shmem_initxattrs, NULL);
1861 if (error && error != -EOPNOTSUPP)
1862 goto out_iput;
1863
1864 error = 0;
1865 dir->i_size += BOGO_DIRENT_SIZE;
1866 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1867 d_instantiate(dentry, inode);
1868 dget(dentry); /* Extra count - pin the dentry in core */
1869 }
1870 return error;
1871out_iput:
1872 iput(inode);
1873 return error;
1874}
1875
1876static int
1877shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
1878{
1879 struct inode *inode;
1880 int error = -ENOSPC;
1881
1882 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
1883 if (inode) {
1884 error = security_inode_init_security(inode, dir,
1885 NULL,
1886 shmem_initxattrs, NULL);
1887 if (error && error != -EOPNOTSUPP)
1888 goto out_iput;
1889 error = simple_acl_create(dir, inode);
1890 if (error)
1891 goto out_iput;
1892 d_tmpfile(dentry, inode);
1893 }
1894 return error;
1895out_iput:
1896 iput(inode);
1897 return error;
1898}
1899
1900static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1901{
1902 int error;
1903
1904 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1905 return error;
1906 inc_nlink(dir);
1907 return 0;
1908}
1909
1910static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
1911 bool excl)
1912{
1913 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1914}
1915
1916/*
1917 * Link a file..
1918 */
1919static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1920{
1921 struct inode *inode = old_dentry->d_inode;
1922 int ret;
1923
1924 /*
1925 * No ordinary (disk based) filesystem counts links as inodes;
1926 * but each new link needs a new dentry, pinning lowmem, and
1927 * tmpfs dentries cannot be pruned until they are unlinked.
1928 */
1929 ret = shmem_reserve_inode(inode->i_sb);
1930 if (ret)
1931 goto out;
1932
1933 dir->i_size += BOGO_DIRENT_SIZE;
1934 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1935 inc_nlink(inode);
1936 ihold(inode); /* New dentry reference */
1937 dget(dentry); /* Extra pinning count for the created dentry */
1938 d_instantiate(dentry, inode);
1939out:
1940 return ret;
1941}
1942
1943static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1944{
1945 struct inode *inode = dentry->d_inode;
1946
1947 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1948 shmem_free_inode(inode->i_sb);
1949
1950 dir->i_size -= BOGO_DIRENT_SIZE;
1951 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1952 drop_nlink(inode);
1953 dput(dentry); /* Undo the count from "create" - this does all the work */
1954 return 0;
1955}
1956
1957static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1958{
1959 if (!simple_empty(dentry))
1960 return -ENOTEMPTY;
1961
1962 drop_nlink(dentry->d_inode);
1963 drop_nlink(dir);
1964 return shmem_unlink(dir, dentry);
1965}
1966
1967/*
1968 * The VFS layer already does all the dentry stuff for rename,
1969 * we just have to decrement the usage count for the target if
1970 * it exists so that the VFS layer correctly free's it when it
1971 * gets overwritten.
1972 */
1973static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1974{
1975 struct inode *inode = old_dentry->d_inode;
1976 int they_are_dirs = S_ISDIR(inode->i_mode);
1977
1978 if (!simple_empty(new_dentry))
1979 return -ENOTEMPTY;
1980
1981 if (new_dentry->d_inode) {
1982 (void) shmem_unlink(new_dir, new_dentry);
1983 if (they_are_dirs)
1984 drop_nlink(old_dir);
1985 } else if (they_are_dirs) {
1986 drop_nlink(old_dir);
1987 inc_nlink(new_dir);
1988 }
1989
1990 old_dir->i_size -= BOGO_DIRENT_SIZE;
1991 new_dir->i_size += BOGO_DIRENT_SIZE;
1992 old_dir->i_ctime = old_dir->i_mtime =
1993 new_dir->i_ctime = new_dir->i_mtime =
1994 inode->i_ctime = CURRENT_TIME;
1995 return 0;
1996}
1997
1998static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1999{
2000 int error;
2001 int len;
2002 struct inode *inode;
2003 struct page *page;
2004 char *kaddr;
2005 struct shmem_inode_info *info;
2006
2007 len = strlen(symname) + 1;
2008 if (len > PAGE_CACHE_SIZE)
2009 return -ENAMETOOLONG;
2010
2011 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
2012 if (!inode)
2013 return -ENOSPC;
2014
2015 error = security_inode_init_security(inode, dir, &dentry->d_name,
2016 shmem_initxattrs, NULL);
2017 if (error) {
2018 if (error != -EOPNOTSUPP) {
2019 iput(inode);
2020 return error;
2021 }
2022 error = 0;
2023 }
2024
2025 info = SHMEM_I(inode);
2026 inode->i_size = len-1;
2027 if (len <= SHORT_SYMLINK_LEN) {
2028 info->symlink = kmemdup(symname, len, GFP_KERNEL);
2029 if (!info->symlink) {
2030 iput(inode);
2031 return -ENOMEM;
2032 }
2033 inode->i_op = &shmem_short_symlink_operations;
2034 } else {
2035 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2036 if (error) {
2037 iput(inode);
2038 return error;
2039 }
2040 inode->i_mapping->a_ops = &shmem_aops;
2041 inode->i_op = &shmem_symlink_inode_operations;
2042 kaddr = kmap_atomic(page);
2043 memcpy(kaddr, symname, len);
2044 kunmap_atomic(kaddr);
2045 SetPageUptodate(page);
2046 set_page_dirty(page);
2047 unlock_page(page);
2048 page_cache_release(page);
2049 }
2050 dir->i_size += BOGO_DIRENT_SIZE;
2051 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2052 d_instantiate(dentry, inode);
2053 dget(dentry);
2054 return 0;
2055}
2056
2057static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
2058{
2059 nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink);
2060 return NULL;
2061}
2062
2063static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
2064{
2065 struct page *page = NULL;
2066 int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2067 nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
2068 if (page)
2069 unlock_page(page);
2070 return page;
2071}
2072
2073static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2074{
2075 if (!IS_ERR(nd_get_link(nd))) {
2076 struct page *page = cookie;
2077 kunmap(page);
2078 mark_page_accessed(page);
2079 page_cache_release(page);
2080 }
2081}
2082
2083#ifdef CONFIG_TMPFS_XATTR
2084/*
2085 * Superblocks without xattr inode operations may get some security.* xattr
2086 * support from the LSM "for free". As soon as we have any other xattrs
2087 * like ACLs, we also need to implement the security.* handlers at
2088 * filesystem level, though.
2089 */
2090
2091/*
2092 * Callback for security_inode_init_security() for acquiring xattrs.
2093 */
2094static int shmem_initxattrs(struct inode *inode,
2095 const struct xattr *xattr_array,
2096 void *fs_info)
2097{
2098 struct shmem_inode_info *info = SHMEM_I(inode);
2099 const struct xattr *xattr;
2100 struct simple_xattr *new_xattr;
2101 size_t len;
2102
2103 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
2104 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
2105 if (!new_xattr)
2106 return -ENOMEM;
2107
2108 len = strlen(xattr->name) + 1;
2109 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
2110 GFP_KERNEL);
2111 if (!new_xattr->name) {
2112 kfree(new_xattr);
2113 return -ENOMEM;
2114 }
2115
2116 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
2117 XATTR_SECURITY_PREFIX_LEN);
2118 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
2119 xattr->name, len);
2120
2121 simple_xattr_list_add(&info->xattrs, new_xattr);
2122 }
2123
2124 return 0;
2125}
2126
2127static const struct xattr_handler *shmem_xattr_handlers[] = {
2128#ifdef CONFIG_TMPFS_POSIX_ACL
2129 &posix_acl_access_xattr_handler,
2130 &posix_acl_default_xattr_handler,
2131#endif
2132 NULL
2133};
2134
2135static int shmem_xattr_validate(const char *name)
2136{
2137 struct { const char *prefix; size_t len; } arr[] = {
2138 { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
2139 { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
2140 };
2141 int i;
2142
2143 for (i = 0; i < ARRAY_SIZE(arr); i++) {
2144 size_t preflen = arr[i].len;
2145 if (strncmp(name, arr[i].prefix, preflen) == 0) {
2146 if (!name[preflen])
2147 return -EINVAL;
2148 return 0;
2149 }
2150 }
2151 return -EOPNOTSUPP;
2152}
2153
2154static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
2155 void *buffer, size_t size)
2156{
2157 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2158 int err;
2159
2160 /*
2161 * If this is a request for a synthetic attribute in the system.*
2162 * namespace use the generic infrastructure to resolve a handler
2163 * for it via sb->s_xattr.
2164 */
2165 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2166 return generic_getxattr(dentry, name, buffer, size);
2167
2168 err = shmem_xattr_validate(name);
2169 if (err)
2170 return err;
2171
2172 return simple_xattr_get(&info->xattrs, name, buffer, size);
2173}
2174
2175static int shmem_setxattr(struct dentry *dentry, const char *name,
2176 const void *value, size_t size, int flags)
2177{
2178 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2179 int err;
2180
2181 /*
2182 * If this is a request for a synthetic attribute in the system.*
2183 * namespace use the generic infrastructure to resolve a handler
2184 * for it via sb->s_xattr.
2185 */
2186 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2187 return generic_setxattr(dentry, name, value, size, flags);
2188
2189 err = shmem_xattr_validate(name);
2190 if (err)
2191 return err;
2192
2193 return simple_xattr_set(&info->xattrs, name, value, size, flags);
2194}
2195
2196static int shmem_removexattr(struct dentry *dentry, const char *name)
2197{
2198 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2199 int err;
2200
2201 /*
2202 * If this is a request for a synthetic attribute in the system.*
2203 * namespace use the generic infrastructure to resolve a handler
2204 * for it via sb->s_xattr.
2205 */
2206 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2207 return generic_removexattr(dentry, name);
2208
2209 err = shmem_xattr_validate(name);
2210 if (err)
2211 return err;
2212
2213 return simple_xattr_remove(&info->xattrs, name);
2214}
2215
2216static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
2217{
2218 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2219 return simple_xattr_list(&info->xattrs, buffer, size);
2220}
2221#endif /* CONFIG_TMPFS_XATTR */
2222
2223static const struct inode_operations shmem_short_symlink_operations = {
2224 .readlink = generic_readlink,
2225 .follow_link = shmem_follow_short_symlink,
2226#ifdef CONFIG_TMPFS_XATTR
2227 .setxattr = shmem_setxattr,
2228 .getxattr = shmem_getxattr,
2229 .listxattr = shmem_listxattr,
2230 .removexattr = shmem_removexattr,
2231#endif
2232};
2233
2234static const struct inode_operations shmem_symlink_inode_operations = {
2235 .readlink = generic_readlink,
2236 .follow_link = shmem_follow_link,
2237 .put_link = shmem_put_link,
2238#ifdef CONFIG_TMPFS_XATTR
2239 .setxattr = shmem_setxattr,
2240 .getxattr = shmem_getxattr,
2241 .listxattr = shmem_listxattr,
2242 .removexattr = shmem_removexattr,
2243#endif
2244};
2245
2246static struct dentry *shmem_get_parent(struct dentry *child)
2247{
2248 return ERR_PTR(-ESTALE);
2249}
2250
2251static int shmem_match(struct inode *ino, void *vfh)
2252{
2253 __u32 *fh = vfh;
2254 __u64 inum = fh[2];
2255 inum = (inum << 32) | fh[1];
2256 return ino->i_ino == inum && fh[0] == ino->i_generation;
2257}
2258
2259static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2260 struct fid *fid, int fh_len, int fh_type)
2261{
2262 struct inode *inode;
2263 struct dentry *dentry = NULL;
2264 u64 inum;
2265
2266 if (fh_len < 3)
2267 return NULL;
2268
2269 inum = fid->raw[2];
2270 inum = (inum << 32) | fid->raw[1];
2271
2272 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2273 shmem_match, fid->raw);
2274 if (inode) {
2275 dentry = d_find_alias(inode);
2276 iput(inode);
2277 }
2278
2279 return dentry;
2280}
2281
2282static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
2283 struct inode *parent)
2284{
2285 if (*len < 3) {
2286 *len = 3;
2287 return FILEID_INVALID;
2288 }
2289
2290 if (inode_unhashed(inode)) {
2291 /* Unfortunately insert_inode_hash is not idempotent,
2292 * so as we hash inodes here rather than at creation
2293 * time, we need a lock to ensure we only try
2294 * to do it once
2295 */
2296 static DEFINE_SPINLOCK(lock);
2297 spin_lock(&lock);
2298 if (inode_unhashed(inode))
2299 __insert_inode_hash(inode,
2300 inode->i_ino + inode->i_generation);
2301 spin_unlock(&lock);
2302 }
2303
2304 fh[0] = inode->i_generation;
2305 fh[1] = inode->i_ino;
2306 fh[2] = ((__u64)inode->i_ino) >> 32;
2307
2308 *len = 3;
2309 return 1;
2310}
2311
2312static const struct export_operations shmem_export_ops = {
2313 .get_parent = shmem_get_parent,
2314 .encode_fh = shmem_encode_fh,
2315 .fh_to_dentry = shmem_fh_to_dentry,
2316};
2317
2318static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2319 bool remount)
2320{
2321 char *this_char, *value, *rest;
2322 struct mempolicy *mpol = NULL;
2323 uid_t uid;
2324 gid_t gid;
2325
2326 while (options != NULL) {
2327 this_char = options;
2328 for (;;) {
2329 /*
2330 * NUL-terminate this option: unfortunately,
2331 * mount options form a comma-separated list,
2332 * but mpol's nodelist may also contain commas.
2333 */
2334 options = strchr(options, ',');
2335 if (options == NULL)
2336 break;
2337 options++;
2338 if (!isdigit(*options)) {
2339 options[-1] = '\0';
2340 break;
2341 }
2342 }
2343 if (!*this_char)
2344 continue;
2345 if ((value = strchr(this_char,'=')) != NULL) {
2346 *value++ = 0;
2347 } else {
2348 printk(KERN_ERR
2349 "tmpfs: No value for mount option '%s'\n",
2350 this_char);
2351 goto error;
2352 }
2353
2354 if (!strcmp(this_char,"size")) {
2355 unsigned long long size;
2356 size = memparse(value,&rest);
2357 if (*rest == '%') {
2358 size <<= PAGE_SHIFT;
2359 size *= totalram_pages;
2360 do_div(size, 100);
2361 rest++;
2362 }
2363 if (*rest)
2364 goto bad_val;
2365 sbinfo->max_blocks =
2366 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2367 } else if (!strcmp(this_char,"nr_blocks")) {
2368 sbinfo->max_blocks = memparse(value, &rest);
2369 if (*rest)
2370 goto bad_val;
2371 } else if (!strcmp(this_char,"nr_inodes")) {
2372 sbinfo->max_inodes = memparse(value, &rest);
2373 if (*rest)
2374 goto bad_val;
2375 } else if (!strcmp(this_char,"mode")) {
2376 if (remount)
2377 continue;
2378 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2379 if (*rest)
2380 goto bad_val;
2381 } else if (!strcmp(this_char,"uid")) {
2382 if (remount)
2383 continue;
2384 uid = simple_strtoul(value, &rest, 0);
2385 if (*rest)
2386 goto bad_val;
2387 sbinfo->uid = make_kuid(current_user_ns(), uid);
2388 if (!uid_valid(sbinfo->uid))
2389 goto bad_val;
2390 } else if (!strcmp(this_char,"gid")) {
2391 if (remount)
2392 continue;
2393 gid = simple_strtoul(value, &rest, 0);
2394 if (*rest)
2395 goto bad_val;
2396 sbinfo->gid = make_kgid(current_user_ns(), gid);
2397 if (!gid_valid(sbinfo->gid))
2398 goto bad_val;
2399 } else if (!strcmp(this_char,"mpol")) {
2400 mpol_put(mpol);
2401 mpol = NULL;
2402 if (mpol_parse_str(value, &mpol))
2403 goto bad_val;
2404 } else {
2405 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2406 this_char);
2407 goto error;
2408 }
2409 }
2410 sbinfo->mpol = mpol;
2411 return 0;
2412
2413bad_val:
2414 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2415 value, this_char);
2416error:
2417 mpol_put(mpol);
2418 return 1;
2419
2420}
2421
2422static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2423{
2424 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2425 struct shmem_sb_info config = *sbinfo;
2426 unsigned long inodes;
2427 int error = -EINVAL;
2428
2429 config.mpol = NULL;
2430 if (shmem_parse_options(data, &config, true))
2431 return error;
2432
2433 spin_lock(&sbinfo->stat_lock);
2434 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2435 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
2436 goto out;
2437 if (config.max_inodes < inodes)
2438 goto out;
2439 /*
2440 * Those tests disallow limited->unlimited while any are in use;
2441 * but we must separately disallow unlimited->limited, because
2442 * in that case we have no record of how much is already in use.
2443 */
2444 if (config.max_blocks && !sbinfo->max_blocks)
2445 goto out;
2446 if (config.max_inodes && !sbinfo->max_inodes)
2447 goto out;
2448
2449 error = 0;
2450 sbinfo->max_blocks = config.max_blocks;
2451 sbinfo->max_inodes = config.max_inodes;
2452 sbinfo->free_inodes = config.max_inodes - inodes;
2453
2454 /*
2455 * Preserve previous mempolicy unless mpol remount option was specified.
2456 */
2457 if (config.mpol) {
2458 mpol_put(sbinfo->mpol);
2459 sbinfo->mpol = config.mpol; /* transfers initial ref */
2460 }
2461out:
2462 spin_unlock(&sbinfo->stat_lock);
2463 return error;
2464}
2465
2466static int shmem_show_options(struct seq_file *seq, struct dentry *root)
2467{
2468 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
2469
2470 if (sbinfo->max_blocks != shmem_default_max_blocks())
2471 seq_printf(seq, ",size=%luk",
2472 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2473 if (sbinfo->max_inodes != shmem_default_max_inodes())
2474 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2475 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2476 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
2477 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
2478 seq_printf(seq, ",uid=%u",
2479 from_kuid_munged(&init_user_ns, sbinfo->uid));
2480 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
2481 seq_printf(seq, ",gid=%u",
2482 from_kgid_munged(&init_user_ns, sbinfo->gid));
2483 shmem_show_mpol(seq, sbinfo->mpol);
2484 return 0;
2485}
2486#endif /* CONFIG_TMPFS */
2487
2488static void shmem_put_super(struct super_block *sb)
2489{
2490 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2491
2492 percpu_counter_destroy(&sbinfo->used_blocks);
2493 mpol_put(sbinfo->mpol);
2494 kfree(sbinfo);
2495 sb->s_fs_info = NULL;
2496}
2497
2498int shmem_fill_super(struct super_block *sb, void *data, int silent)
2499{
2500 struct inode *inode;
2501 struct shmem_sb_info *sbinfo;
2502 int err = -ENOMEM;
2503
2504 /* Round up to L1_CACHE_BYTES to resist false sharing */
2505 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2506 L1_CACHE_BYTES), GFP_KERNEL);
2507 if (!sbinfo)
2508 return -ENOMEM;
2509
2510 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2511 sbinfo->uid = current_fsuid();
2512 sbinfo->gid = current_fsgid();
2513 sb->s_fs_info = sbinfo;
2514
2515#ifdef CONFIG_TMPFS
2516 /*
2517 * Per default we only allow half of the physical ram per
2518 * tmpfs instance, limiting inodes to one per page of lowmem;
2519 * but the internal instance is left unlimited.
2520 */
2521 if (!(sb->s_flags & MS_KERNMOUNT)) {
2522 sbinfo->max_blocks = shmem_default_max_blocks();
2523 sbinfo->max_inodes = shmem_default_max_inodes();
2524 if (shmem_parse_options(data, sbinfo, false)) {
2525 err = -EINVAL;
2526 goto failed;
2527 }
2528 } else {
2529 sb->s_flags |= MS_NOUSER;
2530 }
2531 sb->s_export_op = &shmem_export_ops;
2532 sb->s_flags |= MS_NOSEC;
2533#else
2534 sb->s_flags |= MS_NOUSER;
2535#endif
2536
2537 spin_lock_init(&sbinfo->stat_lock);
2538 if (percpu_counter_init(&sbinfo->used_blocks, 0))
2539 goto failed;
2540 sbinfo->free_inodes = sbinfo->max_inodes;
2541
2542 sb->s_maxbytes = MAX_LFS_FILESIZE;
2543 sb->s_blocksize = PAGE_CACHE_SIZE;
2544 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2545 sb->s_magic = TMPFS_MAGIC;
2546 sb->s_op = &shmem_ops;
2547 sb->s_time_gran = 1;
2548#ifdef CONFIG_TMPFS_XATTR
2549 sb->s_xattr = shmem_xattr_handlers;
2550#endif
2551#ifdef CONFIG_TMPFS_POSIX_ACL
2552 sb->s_flags |= MS_POSIXACL;
2553#endif
2554
2555 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2556 if (!inode)
2557 goto failed;
2558 inode->i_uid = sbinfo->uid;
2559 inode->i_gid = sbinfo->gid;
2560 sb->s_root = d_make_root(inode);
2561 if (!sb->s_root)
2562 goto failed;
2563 return 0;
2564
2565failed:
2566 shmem_put_super(sb);
2567 return err;
2568}
2569
2570static struct kmem_cache *shmem_inode_cachep;
2571
2572static struct inode *shmem_alloc_inode(struct super_block *sb)
2573{
2574 struct shmem_inode_info *info;
2575 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2576 if (!info)
2577 return NULL;
2578 return &info->vfs_inode;
2579}
2580
2581static void shmem_destroy_callback(struct rcu_head *head)
2582{
2583 struct inode *inode = container_of(head, struct inode, i_rcu);
2584 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2585}
2586
2587static void shmem_destroy_inode(struct inode *inode)
2588{
2589 if (S_ISREG(inode->i_mode))
2590 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2591 call_rcu(&inode->i_rcu, shmem_destroy_callback);
2592}
2593
2594static void shmem_init_inode(void *foo)
2595{
2596 struct shmem_inode_info *info = foo;
2597 inode_init_once(&info->vfs_inode);
2598}
2599
2600static int shmem_init_inodecache(void)
2601{
2602 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2603 sizeof(struct shmem_inode_info),
2604 0, SLAB_PANIC, shmem_init_inode);
2605 return 0;
2606}
2607
2608static void shmem_destroy_inodecache(void)
2609{
2610 kmem_cache_destroy(shmem_inode_cachep);
2611}
2612
2613static const struct address_space_operations shmem_aops = {
2614 .writepage = shmem_writepage,
2615 .set_page_dirty = __set_page_dirty_no_writeback,
2616#ifdef CONFIG_TMPFS
2617 .write_begin = shmem_write_begin,
2618 .write_end = shmem_write_end,
2619#endif
2620 .migratepage = migrate_page,
2621 .error_remove_page = generic_error_remove_page,
2622};
2623
2624static const struct file_operations shmem_file_operations = {
2625 .mmap = shmem_mmap,
2626#ifdef CONFIG_TMPFS
2627 .llseek = shmem_file_llseek,
2628 .read = do_sync_read,
2629 .write = do_sync_write,
2630 .aio_read = shmem_file_aio_read,
2631 .aio_write = generic_file_aio_write,
2632 .fsync = noop_fsync,
2633 .splice_read = shmem_file_splice_read,
2634 .splice_write = generic_file_splice_write,
2635 .fallocate = shmem_fallocate,
2636#endif
2637};
2638
2639static const struct inode_operations shmem_inode_operations = {
2640 .setattr = shmem_setattr,
2641#ifdef CONFIG_TMPFS_XATTR
2642 .setxattr = shmem_setxattr,
2643 .getxattr = shmem_getxattr,
2644 .listxattr = shmem_listxattr,
2645 .removexattr = shmem_removexattr,
2646 .set_acl = simple_set_acl,
2647#endif
2648};
2649
2650static const struct inode_operations shmem_dir_inode_operations = {
2651#ifdef CONFIG_TMPFS
2652 .create = shmem_create,
2653 .lookup = simple_lookup,
2654 .link = shmem_link,
2655 .unlink = shmem_unlink,
2656 .symlink = shmem_symlink,
2657 .mkdir = shmem_mkdir,
2658 .rmdir = shmem_rmdir,
2659 .mknod = shmem_mknod,
2660 .rename = shmem_rename,
2661 .tmpfile = shmem_tmpfile,
2662#endif
2663#ifdef CONFIG_TMPFS_XATTR
2664 .setxattr = shmem_setxattr,
2665 .getxattr = shmem_getxattr,
2666 .listxattr = shmem_listxattr,
2667 .removexattr = shmem_removexattr,
2668#endif
2669#ifdef CONFIG_TMPFS_POSIX_ACL
2670 .setattr = shmem_setattr,
2671 .set_acl = simple_set_acl,
2672#endif
2673};
2674
2675static const struct inode_operations shmem_special_inode_operations = {
2676#ifdef CONFIG_TMPFS_XATTR
2677 .setxattr = shmem_setxattr,
2678 .getxattr = shmem_getxattr,
2679 .listxattr = shmem_listxattr,
2680 .removexattr = shmem_removexattr,
2681#endif
2682#ifdef CONFIG_TMPFS_POSIX_ACL
2683 .setattr = shmem_setattr,
2684 .set_acl = simple_set_acl,
2685#endif
2686};
2687
2688static const struct super_operations shmem_ops = {
2689 .alloc_inode = shmem_alloc_inode,
2690 .destroy_inode = shmem_destroy_inode,
2691#ifdef CONFIG_TMPFS
2692 .statfs = shmem_statfs,
2693 .remount_fs = shmem_remount_fs,
2694 .show_options = shmem_show_options,
2695#endif
2696 .evict_inode = shmem_evict_inode,
2697 .drop_inode = generic_delete_inode,
2698 .put_super = shmem_put_super,
2699};
2700
2701static const struct vm_operations_struct shmem_vm_ops = {
2702 .fault = shmem_fault,
2703 .map_pages = filemap_map_pages,
2704#ifdef CONFIG_NUMA
2705 .set_policy = shmem_set_policy,
2706 .get_policy = shmem_get_policy,
2707#endif
2708 .remap_pages = generic_file_remap_pages,
2709};
2710
2711static struct dentry *shmem_mount(struct file_system_type *fs_type,
2712 int flags, const char *dev_name, void *data)
2713{
2714 return mount_nodev(fs_type, flags, data, shmem_fill_super);
2715}
2716
2717static struct file_system_type shmem_fs_type = {
2718 .owner = THIS_MODULE,
2719 .name = "tmpfs",
2720 .mount = shmem_mount,
2721 .kill_sb = kill_litter_super,
2722 .fs_flags = FS_USERNS_MOUNT,
2723};
2724
2725int __init shmem_init(void)
2726{
2727 int error;
2728
2729 /* If rootfs called this, don't re-init */
2730 if (shmem_inode_cachep)
2731 return 0;
2732
2733 error = bdi_init(&shmem_backing_dev_info);
2734 if (error)
2735 goto out4;
2736
2737 error = shmem_init_inodecache();
2738 if (error)
2739 goto out3;
2740
2741 error = register_filesystem(&shmem_fs_type);
2742 if (error) {
2743 printk(KERN_ERR "Could not register tmpfs\n");
2744 goto out2;
2745 }
2746
2747 shm_mnt = kern_mount(&shmem_fs_type);
2748 if (IS_ERR(shm_mnt)) {
2749 error = PTR_ERR(shm_mnt);
2750 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2751 goto out1;
2752 }
2753 return 0;
2754
2755out1:
2756 unregister_filesystem(&shmem_fs_type);
2757out2:
2758 shmem_destroy_inodecache();
2759out3:
2760 bdi_destroy(&shmem_backing_dev_info);
2761out4:
2762 shm_mnt = ERR_PTR(error);
2763 return error;
2764}
2765
2766#else /* !CONFIG_SHMEM */
2767
2768/*
2769 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2770 *
2771 * This is intended for small system where the benefits of the full
2772 * shmem code (swap-backed and resource-limited) are outweighed by
2773 * their complexity. On systems without swap this code should be
2774 * effectively equivalent, but much lighter weight.
2775 */
2776
2777static struct file_system_type shmem_fs_type = {
2778 .name = "tmpfs",
2779 .mount = ramfs_mount,
2780 .kill_sb = kill_litter_super,
2781 .fs_flags = FS_USERNS_MOUNT,
2782};
2783
2784int __init shmem_init(void)
2785{
2786 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
2787
2788 shm_mnt = kern_mount(&shmem_fs_type);
2789 BUG_ON(IS_ERR(shm_mnt));
2790
2791 return 0;
2792}
2793
2794int shmem_unuse(swp_entry_t swap, struct page *page)
2795{
2796 return 0;
2797}
2798
2799int shmem_lock(struct file *file, int lock, struct user_struct *user)
2800{
2801 return 0;
2802}
2803
2804void shmem_unlock_mapping(struct address_space *mapping)
2805{
2806}
2807
2808void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
2809{
2810 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
2811}
2812EXPORT_SYMBOL_GPL(shmem_truncate_range);
2813
2814#define shmem_vm_ops generic_file_vm_ops
2815#define shmem_file_operations ramfs_file_operations
2816#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2817#define shmem_acct_size(flags, size) 0
2818#define shmem_unacct_size(flags, size) do {} while (0)
2819
2820#endif /* CONFIG_SHMEM */
2821
2822/* common code */
2823
2824static struct dentry_operations anon_ops = {
2825 .d_dname = simple_dname
2826};
2827
2828static struct file *__shmem_file_setup(const char *name, loff_t size,
2829 unsigned long flags, unsigned int i_flags)
2830{
2831 struct file *res;
2832 struct inode *inode;
2833 struct path path;
2834 struct super_block *sb;
2835 struct qstr this;
2836
2837 if (IS_ERR(shm_mnt))
2838 return ERR_CAST(shm_mnt);
2839
2840 if (size < 0 || size > MAX_LFS_FILESIZE)
2841 return ERR_PTR(-EINVAL);
2842
2843 if (shmem_acct_size(flags, size))
2844 return ERR_PTR(-ENOMEM);
2845
2846 res = ERR_PTR(-ENOMEM);
2847 this.name = name;
2848 this.len = strlen(name);
2849 this.hash = 0; /* will go */
2850 sb = shm_mnt->mnt_sb;
2851 path.dentry = d_alloc_pseudo(sb, &this);
2852 if (!path.dentry)
2853 goto put_memory;
2854 d_set_d_op(path.dentry, &anon_ops);
2855 path.mnt = mntget(shm_mnt);
2856
2857 res = ERR_PTR(-ENOSPC);
2858 inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
2859 if (!inode)
2860 goto put_dentry;
2861
2862 inode->i_flags |= i_flags;
2863 d_instantiate(path.dentry, inode);
2864 inode->i_size = size;
2865 clear_nlink(inode); /* It is unlinked */
2866 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
2867 if (IS_ERR(res))
2868 goto put_dentry;
2869
2870 res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2871 &shmem_file_operations);
2872 if (IS_ERR(res))
2873 goto put_dentry;
2874
2875 return res;
2876
2877put_dentry:
2878 path_put(&path);
2879put_memory:
2880 shmem_unacct_size(flags, size);
2881 return res;
2882}
2883
2884/**
2885 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
2886 * kernel internal. There will be NO LSM permission checks against the
2887 * underlying inode. So users of this interface must do LSM checks at a
2888 * higher layer. The one user is the big_key implementation. LSM checks
2889 * are provided at the key level rather than the inode level.
2890 * @name: name for dentry (to be seen in /proc/<pid>/maps
2891 * @size: size to be set for the file
2892 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2893 */
2894struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
2895{
2896 return __shmem_file_setup(name, size, flags, S_PRIVATE);
2897}
2898
2899/**
2900 * shmem_file_setup - get an unlinked file living in tmpfs
2901 * @name: name for dentry (to be seen in /proc/<pid>/maps
2902 * @size: size to be set for the file
2903 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2904 */
2905struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2906{
2907 return __shmem_file_setup(name, size, flags, 0);
2908}
2909EXPORT_SYMBOL_GPL(shmem_file_setup);
2910
2911/**
2912 * shmem_zero_setup - setup a shared anonymous mapping
2913 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2914 */
2915int shmem_zero_setup(struct vm_area_struct *vma)
2916{
2917 struct file *file;
2918 loff_t size = vma->vm_end - vma->vm_start;
2919
2920 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2921 if (IS_ERR(file))
2922 return PTR_ERR(file);
2923
2924 if (vma->vm_file)
2925 fput(vma->vm_file);
2926 vma->vm_file = file;
2927 vma->vm_ops = &shmem_vm_ops;
2928 return 0;
2929}
2930
2931/**
2932 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
2933 * @mapping: the page's address_space
2934 * @index: the page index
2935 * @gfp: the page allocator flags to use if allocating
2936 *
2937 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
2938 * with any new page allocations done using the specified allocation flags.
2939 * But read_cache_page_gfp() uses the ->readpage() method: which does not
2940 * suit tmpfs, since it may have pages in swapcache, and needs to find those
2941 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
2942 *
2943 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
2944 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
2945 */
2946struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
2947 pgoff_t index, gfp_t gfp)
2948{
2949#ifdef CONFIG_SHMEM
2950 struct inode *inode = mapping->host;
2951 struct page *page;
2952 int error;
2953
2954 BUG_ON(mapping->a_ops != &shmem_aops);
2955 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
2956 if (error)
2957 page = ERR_PTR(error);
2958 else
2959 unlock_page(page);
2960 return page;
2961#else
2962 /*
2963 * The tiny !SHMEM case uses ramfs without swap
2964 */
2965 return read_cache_page_gfp(mapping, index, gfp);
2966#endif
2967}
2968EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);