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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/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);
1/*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 *
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
17 *
18 * tiny-shmem:
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 *
21 * This file is released under the GPL.
22 */
23
24#include <linux/fs.h>
25#include <linux/init.h>
26#include <linux/vfs.h>
27#include <linux/mount.h>
28#include <linux/ramfs.h>
29#include <linux/pagemap.h>
30#include <linux/file.h>
31#include <linux/fileattr.h>
32#include <linux/mm.h>
33#include <linux/random.h>
34#include <linux/sched/signal.h>
35#include <linux/export.h>
36#include <linux/shmem_fs.h>
37#include <linux/swap.h>
38#include <linux/uio.h>
39#include <linux/hugetlb.h>
40#include <linux/fs_parser.h>
41#include <linux/swapfile.h>
42#include <linux/iversion.h>
43#include "swap.h"
44
45static struct vfsmount *shm_mnt __ro_after_init;
46
47#ifdef CONFIG_SHMEM
48/*
49 * This virtual memory filesystem is heavily based on the ramfs. It
50 * extends ramfs by the ability to use swap and honor resource limits
51 * which makes it a completely usable filesystem.
52 */
53
54#include <linux/xattr.h>
55#include <linux/exportfs.h>
56#include <linux/posix_acl.h>
57#include <linux/posix_acl_xattr.h>
58#include <linux/mman.h>
59#include <linux/string.h>
60#include <linux/slab.h>
61#include <linux/backing-dev.h>
62#include <linux/writeback.h>
63#include <linux/pagevec.h>
64#include <linux/percpu_counter.h>
65#include <linux/falloc.h>
66#include <linux/splice.h>
67#include <linux/security.h>
68#include <linux/swapops.h>
69#include <linux/mempolicy.h>
70#include <linux/namei.h>
71#include <linux/ctype.h>
72#include <linux/migrate.h>
73#include <linux/highmem.h>
74#include <linux/seq_file.h>
75#include <linux/magic.h>
76#include <linux/syscalls.h>
77#include <linux/fcntl.h>
78#include <uapi/linux/memfd.h>
79#include <linux/rmap.h>
80#include <linux/uuid.h>
81#include <linux/quotaops.h>
82#include <linux/rcupdate_wait.h>
83
84#include <linux/uaccess.h>
85
86#include "internal.h"
87
88#define BLOCKS_PER_PAGE (PAGE_SIZE/512)
89#define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
90
91/* Pretend that each entry is of this size in directory's i_size */
92#define BOGO_DIRENT_SIZE 20
93
94/* Pretend that one inode + its dentry occupy this much memory */
95#define BOGO_INODE_SIZE 1024
96
97/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
98#define SHORT_SYMLINK_LEN 128
99
100/*
101 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
102 * inode->i_private (with i_rwsem making sure that it has only one user at
103 * a time): we would prefer not to enlarge the shmem inode just for that.
104 */
105struct shmem_falloc {
106 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
107 pgoff_t start; /* start of range currently being fallocated */
108 pgoff_t next; /* the next page offset to be fallocated */
109 pgoff_t nr_falloced; /* how many new pages have been fallocated */
110 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
111};
112
113struct shmem_options {
114 unsigned long long blocks;
115 unsigned long long inodes;
116 struct mempolicy *mpol;
117 kuid_t uid;
118 kgid_t gid;
119 umode_t mode;
120 bool full_inums;
121 int huge;
122 int seen;
123 bool noswap;
124 unsigned short quota_types;
125 struct shmem_quota_limits qlimits;
126#define SHMEM_SEEN_BLOCKS 1
127#define SHMEM_SEEN_INODES 2
128#define SHMEM_SEEN_HUGE 4
129#define SHMEM_SEEN_INUMS 8
130#define SHMEM_SEEN_NOSWAP 16
131#define SHMEM_SEEN_QUOTA 32
132};
133
134#ifdef CONFIG_TMPFS
135static unsigned long shmem_default_max_blocks(void)
136{
137 return totalram_pages() / 2;
138}
139
140static unsigned long shmem_default_max_inodes(void)
141{
142 unsigned long nr_pages = totalram_pages();
143
144 return min3(nr_pages - totalhigh_pages(), nr_pages / 2,
145 ULONG_MAX / BOGO_INODE_SIZE);
146}
147#endif
148
149static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
150 struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
151 struct mm_struct *fault_mm, vm_fault_t *fault_type);
152
153static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
154{
155 return sb->s_fs_info;
156}
157
158/*
159 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
160 * for shared memory and for shared anonymous (/dev/zero) mappings
161 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
162 * consistent with the pre-accounting of private mappings ...
163 */
164static inline int shmem_acct_size(unsigned long flags, loff_t size)
165{
166 return (flags & VM_NORESERVE) ?
167 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
168}
169
170static inline void shmem_unacct_size(unsigned long flags, loff_t size)
171{
172 if (!(flags & VM_NORESERVE))
173 vm_unacct_memory(VM_ACCT(size));
174}
175
176static inline int shmem_reacct_size(unsigned long flags,
177 loff_t oldsize, loff_t newsize)
178{
179 if (!(flags & VM_NORESERVE)) {
180 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
181 return security_vm_enough_memory_mm(current->mm,
182 VM_ACCT(newsize) - VM_ACCT(oldsize));
183 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
184 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
185 }
186 return 0;
187}
188
189/*
190 * ... whereas tmpfs objects are accounted incrementally as
191 * pages are allocated, in order to allow large sparse files.
192 * shmem_get_folio reports shmem_acct_blocks failure as -ENOSPC not -ENOMEM,
193 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
194 */
195static inline int shmem_acct_blocks(unsigned long flags, long pages)
196{
197 if (!(flags & VM_NORESERVE))
198 return 0;
199
200 return security_vm_enough_memory_mm(current->mm,
201 pages * VM_ACCT(PAGE_SIZE));
202}
203
204static inline void shmem_unacct_blocks(unsigned long flags, long pages)
205{
206 if (flags & VM_NORESERVE)
207 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
208}
209
210static int shmem_inode_acct_blocks(struct inode *inode, long pages)
211{
212 struct shmem_inode_info *info = SHMEM_I(inode);
213 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
214 int err = -ENOSPC;
215
216 if (shmem_acct_blocks(info->flags, pages))
217 return err;
218
219 might_sleep(); /* when quotas */
220 if (sbinfo->max_blocks) {
221 if (!percpu_counter_limited_add(&sbinfo->used_blocks,
222 sbinfo->max_blocks, pages))
223 goto unacct;
224
225 err = dquot_alloc_block_nodirty(inode, pages);
226 if (err) {
227 percpu_counter_sub(&sbinfo->used_blocks, pages);
228 goto unacct;
229 }
230 } else {
231 err = dquot_alloc_block_nodirty(inode, pages);
232 if (err)
233 goto unacct;
234 }
235
236 return 0;
237
238unacct:
239 shmem_unacct_blocks(info->flags, pages);
240 return err;
241}
242
243static void shmem_inode_unacct_blocks(struct inode *inode, long pages)
244{
245 struct shmem_inode_info *info = SHMEM_I(inode);
246 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
247
248 might_sleep(); /* when quotas */
249 dquot_free_block_nodirty(inode, pages);
250
251 if (sbinfo->max_blocks)
252 percpu_counter_sub(&sbinfo->used_blocks, pages);
253 shmem_unacct_blocks(info->flags, pages);
254}
255
256static const struct super_operations shmem_ops;
257static const struct address_space_operations shmem_aops;
258static const struct file_operations shmem_file_operations;
259static const struct inode_operations shmem_inode_operations;
260static const struct inode_operations shmem_dir_inode_operations;
261static const struct inode_operations shmem_special_inode_operations;
262static const struct vm_operations_struct shmem_vm_ops;
263static const struct vm_operations_struct shmem_anon_vm_ops;
264static struct file_system_type shmem_fs_type;
265
266bool shmem_mapping(struct address_space *mapping)
267{
268 return mapping->a_ops == &shmem_aops;
269}
270EXPORT_SYMBOL_GPL(shmem_mapping);
271
272bool vma_is_anon_shmem(struct vm_area_struct *vma)
273{
274 return vma->vm_ops == &shmem_anon_vm_ops;
275}
276
277bool vma_is_shmem(struct vm_area_struct *vma)
278{
279 return vma_is_anon_shmem(vma) || vma->vm_ops == &shmem_vm_ops;
280}
281
282static LIST_HEAD(shmem_swaplist);
283static DEFINE_MUTEX(shmem_swaplist_mutex);
284
285#ifdef CONFIG_TMPFS_QUOTA
286
287static int shmem_enable_quotas(struct super_block *sb,
288 unsigned short quota_types)
289{
290 int type, err = 0;
291
292 sb_dqopt(sb)->flags |= DQUOT_QUOTA_SYS_FILE | DQUOT_NOLIST_DIRTY;
293 for (type = 0; type < SHMEM_MAXQUOTAS; type++) {
294 if (!(quota_types & (1 << type)))
295 continue;
296 err = dquot_load_quota_sb(sb, type, QFMT_SHMEM,
297 DQUOT_USAGE_ENABLED |
298 DQUOT_LIMITS_ENABLED);
299 if (err)
300 goto out_err;
301 }
302 return 0;
303
304out_err:
305 pr_warn("tmpfs: failed to enable quota tracking (type=%d, err=%d)\n",
306 type, err);
307 for (type--; type >= 0; type--)
308 dquot_quota_off(sb, type);
309 return err;
310}
311
312static void shmem_disable_quotas(struct super_block *sb)
313{
314 int type;
315
316 for (type = 0; type < SHMEM_MAXQUOTAS; type++)
317 dquot_quota_off(sb, type);
318}
319
320static struct dquot __rcu **shmem_get_dquots(struct inode *inode)
321{
322 return SHMEM_I(inode)->i_dquot;
323}
324#endif /* CONFIG_TMPFS_QUOTA */
325
326/*
327 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
328 * produces a novel ino for the newly allocated inode.
329 *
330 * It may also be called when making a hard link to permit the space needed by
331 * each dentry. However, in that case, no new inode number is needed since that
332 * internally draws from another pool of inode numbers (currently global
333 * get_next_ino()). This case is indicated by passing NULL as inop.
334 */
335#define SHMEM_INO_BATCH 1024
336static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
337{
338 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
339 ino_t ino;
340
341 if (!(sb->s_flags & SB_KERNMOUNT)) {
342 raw_spin_lock(&sbinfo->stat_lock);
343 if (sbinfo->max_inodes) {
344 if (sbinfo->free_ispace < BOGO_INODE_SIZE) {
345 raw_spin_unlock(&sbinfo->stat_lock);
346 return -ENOSPC;
347 }
348 sbinfo->free_ispace -= BOGO_INODE_SIZE;
349 }
350 if (inop) {
351 ino = sbinfo->next_ino++;
352 if (unlikely(is_zero_ino(ino)))
353 ino = sbinfo->next_ino++;
354 if (unlikely(!sbinfo->full_inums &&
355 ino > UINT_MAX)) {
356 /*
357 * Emulate get_next_ino uint wraparound for
358 * compatibility
359 */
360 if (IS_ENABLED(CONFIG_64BIT))
361 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
362 __func__, MINOR(sb->s_dev));
363 sbinfo->next_ino = 1;
364 ino = sbinfo->next_ino++;
365 }
366 *inop = ino;
367 }
368 raw_spin_unlock(&sbinfo->stat_lock);
369 } else if (inop) {
370 /*
371 * __shmem_file_setup, one of our callers, is lock-free: it
372 * doesn't hold stat_lock in shmem_reserve_inode since
373 * max_inodes is always 0, and is called from potentially
374 * unknown contexts. As such, use a per-cpu batched allocator
375 * which doesn't require the per-sb stat_lock unless we are at
376 * the batch boundary.
377 *
378 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
379 * shmem mounts are not exposed to userspace, so we don't need
380 * to worry about things like glibc compatibility.
381 */
382 ino_t *next_ino;
383
384 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
385 ino = *next_ino;
386 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
387 raw_spin_lock(&sbinfo->stat_lock);
388 ino = sbinfo->next_ino;
389 sbinfo->next_ino += SHMEM_INO_BATCH;
390 raw_spin_unlock(&sbinfo->stat_lock);
391 if (unlikely(is_zero_ino(ino)))
392 ino++;
393 }
394 *inop = ino;
395 *next_ino = ++ino;
396 put_cpu();
397 }
398
399 return 0;
400}
401
402static void shmem_free_inode(struct super_block *sb, size_t freed_ispace)
403{
404 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
405 if (sbinfo->max_inodes) {
406 raw_spin_lock(&sbinfo->stat_lock);
407 sbinfo->free_ispace += BOGO_INODE_SIZE + freed_ispace;
408 raw_spin_unlock(&sbinfo->stat_lock);
409 }
410}
411
412/**
413 * shmem_recalc_inode - recalculate the block usage of an inode
414 * @inode: inode to recalc
415 * @alloced: the change in number of pages allocated to inode
416 * @swapped: the change in number of pages swapped from inode
417 *
418 * We have to calculate the free blocks since the mm can drop
419 * undirtied hole pages behind our back.
420 *
421 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
422 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
423 */
424static void shmem_recalc_inode(struct inode *inode, long alloced, long swapped)
425{
426 struct shmem_inode_info *info = SHMEM_I(inode);
427 long freed;
428
429 spin_lock(&info->lock);
430 info->alloced += alloced;
431 info->swapped += swapped;
432 freed = info->alloced - info->swapped -
433 READ_ONCE(inode->i_mapping->nrpages);
434 /*
435 * Special case: whereas normally shmem_recalc_inode() is called
436 * after i_mapping->nrpages has already been adjusted (up or down),
437 * shmem_writepage() has to raise swapped before nrpages is lowered -
438 * to stop a racing shmem_recalc_inode() from thinking that a page has
439 * been freed. Compensate here, to avoid the need for a followup call.
440 */
441 if (swapped > 0)
442 freed += swapped;
443 if (freed > 0)
444 info->alloced -= freed;
445 spin_unlock(&info->lock);
446
447 /* The quota case may block */
448 if (freed > 0)
449 shmem_inode_unacct_blocks(inode, freed);
450}
451
452bool shmem_charge(struct inode *inode, long pages)
453{
454 struct address_space *mapping = inode->i_mapping;
455
456 if (shmem_inode_acct_blocks(inode, pages))
457 return false;
458
459 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
460 xa_lock_irq(&mapping->i_pages);
461 mapping->nrpages += pages;
462 xa_unlock_irq(&mapping->i_pages);
463
464 shmem_recalc_inode(inode, pages, 0);
465 return true;
466}
467
468void shmem_uncharge(struct inode *inode, long pages)
469{
470 /* pages argument is currently unused: keep it to help debugging */
471 /* nrpages adjustment done by __filemap_remove_folio() or caller */
472
473 shmem_recalc_inode(inode, 0, 0);
474}
475
476/*
477 * Replace item expected in xarray by a new item, while holding xa_lock.
478 */
479static int shmem_replace_entry(struct address_space *mapping,
480 pgoff_t index, void *expected, void *replacement)
481{
482 XA_STATE(xas, &mapping->i_pages, index);
483 void *item;
484
485 VM_BUG_ON(!expected);
486 VM_BUG_ON(!replacement);
487 item = xas_load(&xas);
488 if (item != expected)
489 return -ENOENT;
490 xas_store(&xas, replacement);
491 return 0;
492}
493
494/*
495 * Sometimes, before we decide whether to proceed or to fail, we must check
496 * that an entry was not already brought back from swap by a racing thread.
497 *
498 * Checking page is not enough: by the time a SwapCache page is locked, it
499 * might be reused, and again be SwapCache, using the same swap as before.
500 */
501static bool shmem_confirm_swap(struct address_space *mapping,
502 pgoff_t index, swp_entry_t swap)
503{
504 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
505}
506
507/*
508 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
509 *
510 * SHMEM_HUGE_NEVER:
511 * disables huge pages for the mount;
512 * SHMEM_HUGE_ALWAYS:
513 * enables huge pages for the mount;
514 * SHMEM_HUGE_WITHIN_SIZE:
515 * only allocate huge pages if the page will be fully within i_size,
516 * also respect fadvise()/madvise() hints;
517 * SHMEM_HUGE_ADVISE:
518 * only allocate huge pages if requested with fadvise()/madvise();
519 */
520
521#define SHMEM_HUGE_NEVER 0
522#define SHMEM_HUGE_ALWAYS 1
523#define SHMEM_HUGE_WITHIN_SIZE 2
524#define SHMEM_HUGE_ADVISE 3
525
526/*
527 * Special values.
528 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
529 *
530 * SHMEM_HUGE_DENY:
531 * disables huge on shm_mnt and all mounts, for emergency use;
532 * SHMEM_HUGE_FORCE:
533 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
534 *
535 */
536#define SHMEM_HUGE_DENY (-1)
537#define SHMEM_HUGE_FORCE (-2)
538
539#ifdef CONFIG_TRANSPARENT_HUGEPAGE
540/* ifdef here to avoid bloating shmem.o when not necessary */
541
542static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
543
544bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
545 struct mm_struct *mm, unsigned long vm_flags)
546{
547 loff_t i_size;
548
549 if (!S_ISREG(inode->i_mode))
550 return false;
551 if (mm && ((vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &mm->flags)))
552 return false;
553 if (shmem_huge == SHMEM_HUGE_DENY)
554 return false;
555 if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE)
556 return true;
557
558 switch (SHMEM_SB(inode->i_sb)->huge) {
559 case SHMEM_HUGE_ALWAYS:
560 return true;
561 case SHMEM_HUGE_WITHIN_SIZE:
562 index = round_up(index + 1, HPAGE_PMD_NR);
563 i_size = round_up(i_size_read(inode), PAGE_SIZE);
564 if (i_size >> PAGE_SHIFT >= index)
565 return true;
566 fallthrough;
567 case SHMEM_HUGE_ADVISE:
568 if (mm && (vm_flags & VM_HUGEPAGE))
569 return true;
570 fallthrough;
571 default:
572 return false;
573 }
574}
575
576#if defined(CONFIG_SYSFS)
577static int shmem_parse_huge(const char *str)
578{
579 if (!strcmp(str, "never"))
580 return SHMEM_HUGE_NEVER;
581 if (!strcmp(str, "always"))
582 return SHMEM_HUGE_ALWAYS;
583 if (!strcmp(str, "within_size"))
584 return SHMEM_HUGE_WITHIN_SIZE;
585 if (!strcmp(str, "advise"))
586 return SHMEM_HUGE_ADVISE;
587 if (!strcmp(str, "deny"))
588 return SHMEM_HUGE_DENY;
589 if (!strcmp(str, "force"))
590 return SHMEM_HUGE_FORCE;
591 return -EINVAL;
592}
593#endif
594
595#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
596static const char *shmem_format_huge(int huge)
597{
598 switch (huge) {
599 case SHMEM_HUGE_NEVER:
600 return "never";
601 case SHMEM_HUGE_ALWAYS:
602 return "always";
603 case SHMEM_HUGE_WITHIN_SIZE:
604 return "within_size";
605 case SHMEM_HUGE_ADVISE:
606 return "advise";
607 case SHMEM_HUGE_DENY:
608 return "deny";
609 case SHMEM_HUGE_FORCE:
610 return "force";
611 default:
612 VM_BUG_ON(1);
613 return "bad_val";
614 }
615}
616#endif
617
618static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
619 struct shrink_control *sc, unsigned long nr_to_split)
620{
621 LIST_HEAD(list), *pos, *next;
622 LIST_HEAD(to_remove);
623 struct inode *inode;
624 struct shmem_inode_info *info;
625 struct folio *folio;
626 unsigned long batch = sc ? sc->nr_to_scan : 128;
627 int split = 0;
628
629 if (list_empty(&sbinfo->shrinklist))
630 return SHRINK_STOP;
631
632 spin_lock(&sbinfo->shrinklist_lock);
633 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
634 info = list_entry(pos, struct shmem_inode_info, shrinklist);
635
636 /* pin the inode */
637 inode = igrab(&info->vfs_inode);
638
639 /* inode is about to be evicted */
640 if (!inode) {
641 list_del_init(&info->shrinklist);
642 goto next;
643 }
644
645 /* Check if there's anything to gain */
646 if (round_up(inode->i_size, PAGE_SIZE) ==
647 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
648 list_move(&info->shrinklist, &to_remove);
649 goto next;
650 }
651
652 list_move(&info->shrinklist, &list);
653next:
654 sbinfo->shrinklist_len--;
655 if (!--batch)
656 break;
657 }
658 spin_unlock(&sbinfo->shrinklist_lock);
659
660 list_for_each_safe(pos, next, &to_remove) {
661 info = list_entry(pos, struct shmem_inode_info, shrinklist);
662 inode = &info->vfs_inode;
663 list_del_init(&info->shrinklist);
664 iput(inode);
665 }
666
667 list_for_each_safe(pos, next, &list) {
668 int ret;
669 pgoff_t index;
670
671 info = list_entry(pos, struct shmem_inode_info, shrinklist);
672 inode = &info->vfs_inode;
673
674 if (nr_to_split && split >= nr_to_split)
675 goto move_back;
676
677 index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
678 folio = filemap_get_folio(inode->i_mapping, index);
679 if (IS_ERR(folio))
680 goto drop;
681
682 /* No huge page at the end of the file: nothing to split */
683 if (!folio_test_large(folio)) {
684 folio_put(folio);
685 goto drop;
686 }
687
688 /*
689 * Move the inode on the list back to shrinklist if we failed
690 * to lock the page at this time.
691 *
692 * Waiting for the lock may lead to deadlock in the
693 * reclaim path.
694 */
695 if (!folio_trylock(folio)) {
696 folio_put(folio);
697 goto move_back;
698 }
699
700 ret = split_folio(folio);
701 folio_unlock(folio);
702 folio_put(folio);
703
704 /* If split failed move the inode on the list back to shrinklist */
705 if (ret)
706 goto move_back;
707
708 split++;
709drop:
710 list_del_init(&info->shrinklist);
711 goto put;
712move_back:
713 /*
714 * Make sure the inode is either on the global list or deleted
715 * from any local list before iput() since it could be deleted
716 * in another thread once we put the inode (then the local list
717 * is corrupted).
718 */
719 spin_lock(&sbinfo->shrinklist_lock);
720 list_move(&info->shrinklist, &sbinfo->shrinklist);
721 sbinfo->shrinklist_len++;
722 spin_unlock(&sbinfo->shrinklist_lock);
723put:
724 iput(inode);
725 }
726
727 return split;
728}
729
730static long shmem_unused_huge_scan(struct super_block *sb,
731 struct shrink_control *sc)
732{
733 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
734
735 if (!READ_ONCE(sbinfo->shrinklist_len))
736 return SHRINK_STOP;
737
738 return shmem_unused_huge_shrink(sbinfo, sc, 0);
739}
740
741static long shmem_unused_huge_count(struct super_block *sb,
742 struct shrink_control *sc)
743{
744 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
745 return READ_ONCE(sbinfo->shrinklist_len);
746}
747#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
748
749#define shmem_huge SHMEM_HUGE_DENY
750
751static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
752 struct shrink_control *sc, unsigned long nr_to_split)
753{
754 return 0;
755}
756#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
757
758/*
759 * Somewhat like filemap_add_folio, but error if expected item has gone.
760 */
761static int shmem_add_to_page_cache(struct folio *folio,
762 struct address_space *mapping,
763 pgoff_t index, void *expected, gfp_t gfp)
764{
765 XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
766 long nr = folio_nr_pages(folio);
767
768 VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
769 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
770 VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
771 VM_BUG_ON(expected && folio_test_large(folio));
772
773 folio_ref_add(folio, nr);
774 folio->mapping = mapping;
775 folio->index = index;
776
777 gfp &= GFP_RECLAIM_MASK;
778 folio_throttle_swaprate(folio, gfp);
779
780 do {
781 xas_lock_irq(&xas);
782 if (expected != xas_find_conflict(&xas)) {
783 xas_set_err(&xas, -EEXIST);
784 goto unlock;
785 }
786 if (expected && xas_find_conflict(&xas)) {
787 xas_set_err(&xas, -EEXIST);
788 goto unlock;
789 }
790 xas_store(&xas, folio);
791 if (xas_error(&xas))
792 goto unlock;
793 if (folio_test_pmd_mappable(folio))
794 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr);
795 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);
796 __lruvec_stat_mod_folio(folio, NR_SHMEM, nr);
797 mapping->nrpages += nr;
798unlock:
799 xas_unlock_irq(&xas);
800 } while (xas_nomem(&xas, gfp));
801
802 if (xas_error(&xas)) {
803 folio->mapping = NULL;
804 folio_ref_sub(folio, nr);
805 return xas_error(&xas);
806 }
807
808 return 0;
809}
810
811/*
812 * Somewhat like filemap_remove_folio, but substitutes swap for @folio.
813 */
814static void shmem_delete_from_page_cache(struct folio *folio, void *radswap)
815{
816 struct address_space *mapping = folio->mapping;
817 long nr = folio_nr_pages(folio);
818 int error;
819
820 xa_lock_irq(&mapping->i_pages);
821 error = shmem_replace_entry(mapping, folio->index, folio, radswap);
822 folio->mapping = NULL;
823 mapping->nrpages -= nr;
824 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, -nr);
825 __lruvec_stat_mod_folio(folio, NR_SHMEM, -nr);
826 xa_unlock_irq(&mapping->i_pages);
827 folio_put(folio);
828 BUG_ON(error);
829}
830
831/*
832 * Remove swap entry from page cache, free the swap and its page cache.
833 */
834static int shmem_free_swap(struct address_space *mapping,
835 pgoff_t index, void *radswap)
836{
837 void *old;
838
839 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
840 if (old != radswap)
841 return -ENOENT;
842 free_swap_and_cache(radix_to_swp_entry(radswap));
843 return 0;
844}
845
846/*
847 * Determine (in bytes) how many of the shmem object's pages mapped by the
848 * given offsets are swapped out.
849 *
850 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
851 * as long as the inode doesn't go away and racy results are not a problem.
852 */
853unsigned long shmem_partial_swap_usage(struct address_space *mapping,
854 pgoff_t start, pgoff_t end)
855{
856 XA_STATE(xas, &mapping->i_pages, start);
857 struct page *page;
858 unsigned long swapped = 0;
859 unsigned long max = end - 1;
860
861 rcu_read_lock();
862 xas_for_each(&xas, page, max) {
863 if (xas_retry(&xas, page))
864 continue;
865 if (xa_is_value(page))
866 swapped++;
867 if (xas.xa_index == max)
868 break;
869 if (need_resched()) {
870 xas_pause(&xas);
871 cond_resched_rcu();
872 }
873 }
874 rcu_read_unlock();
875
876 return swapped << PAGE_SHIFT;
877}
878
879/*
880 * Determine (in bytes) how many of the shmem object's pages mapped by the
881 * given vma is swapped out.
882 *
883 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
884 * as long as the inode doesn't go away and racy results are not a problem.
885 */
886unsigned long shmem_swap_usage(struct vm_area_struct *vma)
887{
888 struct inode *inode = file_inode(vma->vm_file);
889 struct shmem_inode_info *info = SHMEM_I(inode);
890 struct address_space *mapping = inode->i_mapping;
891 unsigned long swapped;
892
893 /* Be careful as we don't hold info->lock */
894 swapped = READ_ONCE(info->swapped);
895
896 /*
897 * The easier cases are when the shmem object has nothing in swap, or
898 * the vma maps it whole. Then we can simply use the stats that we
899 * already track.
900 */
901 if (!swapped)
902 return 0;
903
904 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
905 return swapped << PAGE_SHIFT;
906
907 /* Here comes the more involved part */
908 return shmem_partial_swap_usage(mapping, vma->vm_pgoff,
909 vma->vm_pgoff + vma_pages(vma));
910}
911
912/*
913 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
914 */
915void shmem_unlock_mapping(struct address_space *mapping)
916{
917 struct folio_batch fbatch;
918 pgoff_t index = 0;
919
920 folio_batch_init(&fbatch);
921 /*
922 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
923 */
924 while (!mapping_unevictable(mapping) &&
925 filemap_get_folios(mapping, &index, ~0UL, &fbatch)) {
926 check_move_unevictable_folios(&fbatch);
927 folio_batch_release(&fbatch);
928 cond_resched();
929 }
930}
931
932static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
933{
934 struct folio *folio;
935
936 /*
937 * At first avoid shmem_get_folio(,,,SGP_READ): that fails
938 * beyond i_size, and reports fallocated folios as holes.
939 */
940 folio = filemap_get_entry(inode->i_mapping, index);
941 if (!folio)
942 return folio;
943 if (!xa_is_value(folio)) {
944 folio_lock(folio);
945 if (folio->mapping == inode->i_mapping)
946 return folio;
947 /* The folio has been swapped out */
948 folio_unlock(folio);
949 folio_put(folio);
950 }
951 /*
952 * But read a folio back from swap if any of it is within i_size
953 * (although in some cases this is just a waste of time).
954 */
955 folio = NULL;
956 shmem_get_folio(inode, index, &folio, SGP_READ);
957 return folio;
958}
959
960/*
961 * Remove range of pages and swap entries from page cache, and free them.
962 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
963 */
964static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
965 bool unfalloc)
966{
967 struct address_space *mapping = inode->i_mapping;
968 struct shmem_inode_info *info = SHMEM_I(inode);
969 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
970 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
971 struct folio_batch fbatch;
972 pgoff_t indices[PAGEVEC_SIZE];
973 struct folio *folio;
974 bool same_folio;
975 long nr_swaps_freed = 0;
976 pgoff_t index;
977 int i;
978
979 if (lend == -1)
980 end = -1; /* unsigned, so actually very big */
981
982 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
983 info->fallocend = start;
984
985 folio_batch_init(&fbatch);
986 index = start;
987 while (index < end && find_lock_entries(mapping, &index, end - 1,
988 &fbatch, indices)) {
989 for (i = 0; i < folio_batch_count(&fbatch); i++) {
990 folio = fbatch.folios[i];
991
992 if (xa_is_value(folio)) {
993 if (unfalloc)
994 continue;
995 nr_swaps_freed += !shmem_free_swap(mapping,
996 indices[i], folio);
997 continue;
998 }
999
1000 if (!unfalloc || !folio_test_uptodate(folio))
1001 truncate_inode_folio(mapping, folio);
1002 folio_unlock(folio);
1003 }
1004 folio_batch_remove_exceptionals(&fbatch);
1005 folio_batch_release(&fbatch);
1006 cond_resched();
1007 }
1008
1009 /*
1010 * When undoing a failed fallocate, we want none of the partial folio
1011 * zeroing and splitting below, but shall want to truncate the whole
1012 * folio when !uptodate indicates that it was added by this fallocate,
1013 * even when [lstart, lend] covers only a part of the folio.
1014 */
1015 if (unfalloc)
1016 goto whole_folios;
1017
1018 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
1019 folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT);
1020 if (folio) {
1021 same_folio = lend < folio_pos(folio) + folio_size(folio);
1022 folio_mark_dirty(folio);
1023 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
1024 start = folio_next_index(folio);
1025 if (same_folio)
1026 end = folio->index;
1027 }
1028 folio_unlock(folio);
1029 folio_put(folio);
1030 folio = NULL;
1031 }
1032
1033 if (!same_folio)
1034 folio = shmem_get_partial_folio(inode, lend >> PAGE_SHIFT);
1035 if (folio) {
1036 folio_mark_dirty(folio);
1037 if (!truncate_inode_partial_folio(folio, lstart, lend))
1038 end = folio->index;
1039 folio_unlock(folio);
1040 folio_put(folio);
1041 }
1042
1043whole_folios:
1044
1045 index = start;
1046 while (index < end) {
1047 cond_resched();
1048
1049 if (!find_get_entries(mapping, &index, end - 1, &fbatch,
1050 indices)) {
1051 /* If all gone or hole-punch or unfalloc, we're done */
1052 if (index == start || end != -1)
1053 break;
1054 /* But if truncating, restart to make sure all gone */
1055 index = start;
1056 continue;
1057 }
1058 for (i = 0; i < folio_batch_count(&fbatch); i++) {
1059 folio = fbatch.folios[i];
1060
1061 if (xa_is_value(folio)) {
1062 if (unfalloc)
1063 continue;
1064 if (shmem_free_swap(mapping, indices[i], folio)) {
1065 /* Swap was replaced by page: retry */
1066 index = indices[i];
1067 break;
1068 }
1069 nr_swaps_freed++;
1070 continue;
1071 }
1072
1073 folio_lock(folio);
1074
1075 if (!unfalloc || !folio_test_uptodate(folio)) {
1076 if (folio_mapping(folio) != mapping) {
1077 /* Page was replaced by swap: retry */
1078 folio_unlock(folio);
1079 index = indices[i];
1080 break;
1081 }
1082 VM_BUG_ON_FOLIO(folio_test_writeback(folio),
1083 folio);
1084
1085 if (!folio_test_large(folio)) {
1086 truncate_inode_folio(mapping, folio);
1087 } else if (truncate_inode_partial_folio(folio, lstart, lend)) {
1088 /*
1089 * If we split a page, reset the loop so
1090 * that we pick up the new sub pages.
1091 * Otherwise the THP was entirely
1092 * dropped or the target range was
1093 * zeroed, so just continue the loop as
1094 * is.
1095 */
1096 if (!folio_test_large(folio)) {
1097 folio_unlock(folio);
1098 index = start;
1099 break;
1100 }
1101 }
1102 }
1103 folio_unlock(folio);
1104 }
1105 folio_batch_remove_exceptionals(&fbatch);
1106 folio_batch_release(&fbatch);
1107 }
1108
1109 shmem_recalc_inode(inode, 0, -nr_swaps_freed);
1110}
1111
1112void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1113{
1114 shmem_undo_range(inode, lstart, lend, false);
1115 inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
1116 inode_inc_iversion(inode);
1117}
1118EXPORT_SYMBOL_GPL(shmem_truncate_range);
1119
1120static int shmem_getattr(struct mnt_idmap *idmap,
1121 const struct path *path, struct kstat *stat,
1122 u32 request_mask, unsigned int query_flags)
1123{
1124 struct inode *inode = path->dentry->d_inode;
1125 struct shmem_inode_info *info = SHMEM_I(inode);
1126
1127 if (info->alloced - info->swapped != inode->i_mapping->nrpages)
1128 shmem_recalc_inode(inode, 0, 0);
1129
1130 if (info->fsflags & FS_APPEND_FL)
1131 stat->attributes |= STATX_ATTR_APPEND;
1132 if (info->fsflags & FS_IMMUTABLE_FL)
1133 stat->attributes |= STATX_ATTR_IMMUTABLE;
1134 if (info->fsflags & FS_NODUMP_FL)
1135 stat->attributes |= STATX_ATTR_NODUMP;
1136 stat->attributes_mask |= (STATX_ATTR_APPEND |
1137 STATX_ATTR_IMMUTABLE |
1138 STATX_ATTR_NODUMP);
1139 generic_fillattr(idmap, request_mask, inode, stat);
1140
1141 if (shmem_is_huge(inode, 0, false, NULL, 0))
1142 stat->blksize = HPAGE_PMD_SIZE;
1143
1144 if (request_mask & STATX_BTIME) {
1145 stat->result_mask |= STATX_BTIME;
1146 stat->btime.tv_sec = info->i_crtime.tv_sec;
1147 stat->btime.tv_nsec = info->i_crtime.tv_nsec;
1148 }
1149
1150 return 0;
1151}
1152
1153static int shmem_setattr(struct mnt_idmap *idmap,
1154 struct dentry *dentry, struct iattr *attr)
1155{
1156 struct inode *inode = d_inode(dentry);
1157 struct shmem_inode_info *info = SHMEM_I(inode);
1158 int error;
1159 bool update_mtime = false;
1160 bool update_ctime = true;
1161
1162 error = setattr_prepare(idmap, dentry, attr);
1163 if (error)
1164 return error;
1165
1166 if ((info->seals & F_SEAL_EXEC) && (attr->ia_valid & ATTR_MODE)) {
1167 if ((inode->i_mode ^ attr->ia_mode) & 0111) {
1168 return -EPERM;
1169 }
1170 }
1171
1172 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1173 loff_t oldsize = inode->i_size;
1174 loff_t newsize = attr->ia_size;
1175
1176 /* protected by i_rwsem */
1177 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1178 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1179 return -EPERM;
1180
1181 if (newsize != oldsize) {
1182 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1183 oldsize, newsize);
1184 if (error)
1185 return error;
1186 i_size_write(inode, newsize);
1187 update_mtime = true;
1188 } else {
1189 update_ctime = false;
1190 }
1191 if (newsize <= oldsize) {
1192 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1193 if (oldsize > holebegin)
1194 unmap_mapping_range(inode->i_mapping,
1195 holebegin, 0, 1);
1196 if (info->alloced)
1197 shmem_truncate_range(inode,
1198 newsize, (loff_t)-1);
1199 /* unmap again to remove racily COWed private pages */
1200 if (oldsize > holebegin)
1201 unmap_mapping_range(inode->i_mapping,
1202 holebegin, 0, 1);
1203 }
1204 }
1205
1206 if (is_quota_modification(idmap, inode, attr)) {
1207 error = dquot_initialize(inode);
1208 if (error)
1209 return error;
1210 }
1211
1212 /* Transfer quota accounting */
1213 if (i_uid_needs_update(idmap, attr, inode) ||
1214 i_gid_needs_update(idmap, attr, inode)) {
1215 error = dquot_transfer(idmap, inode, attr);
1216 if (error)
1217 return error;
1218 }
1219
1220 setattr_copy(idmap, inode, attr);
1221 if (attr->ia_valid & ATTR_MODE)
1222 error = posix_acl_chmod(idmap, dentry, inode->i_mode);
1223 if (!error && update_ctime) {
1224 inode_set_ctime_current(inode);
1225 if (update_mtime)
1226 inode_set_mtime_to_ts(inode, inode_get_ctime(inode));
1227 inode_inc_iversion(inode);
1228 }
1229 return error;
1230}
1231
1232static void shmem_evict_inode(struct inode *inode)
1233{
1234 struct shmem_inode_info *info = SHMEM_I(inode);
1235 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1236 size_t freed = 0;
1237
1238 if (shmem_mapping(inode->i_mapping)) {
1239 shmem_unacct_size(info->flags, inode->i_size);
1240 inode->i_size = 0;
1241 mapping_set_exiting(inode->i_mapping);
1242 shmem_truncate_range(inode, 0, (loff_t)-1);
1243 if (!list_empty(&info->shrinklist)) {
1244 spin_lock(&sbinfo->shrinklist_lock);
1245 if (!list_empty(&info->shrinklist)) {
1246 list_del_init(&info->shrinklist);
1247 sbinfo->shrinklist_len--;
1248 }
1249 spin_unlock(&sbinfo->shrinklist_lock);
1250 }
1251 while (!list_empty(&info->swaplist)) {
1252 /* Wait while shmem_unuse() is scanning this inode... */
1253 wait_var_event(&info->stop_eviction,
1254 !atomic_read(&info->stop_eviction));
1255 mutex_lock(&shmem_swaplist_mutex);
1256 /* ...but beware of the race if we peeked too early */
1257 if (!atomic_read(&info->stop_eviction))
1258 list_del_init(&info->swaplist);
1259 mutex_unlock(&shmem_swaplist_mutex);
1260 }
1261 }
1262
1263 simple_xattrs_free(&info->xattrs, sbinfo->max_inodes ? &freed : NULL);
1264 shmem_free_inode(inode->i_sb, freed);
1265 WARN_ON(inode->i_blocks);
1266 clear_inode(inode);
1267#ifdef CONFIG_TMPFS_QUOTA
1268 dquot_free_inode(inode);
1269 dquot_drop(inode);
1270#endif
1271}
1272
1273static int shmem_find_swap_entries(struct address_space *mapping,
1274 pgoff_t start, struct folio_batch *fbatch,
1275 pgoff_t *indices, unsigned int type)
1276{
1277 XA_STATE(xas, &mapping->i_pages, start);
1278 struct folio *folio;
1279 swp_entry_t entry;
1280
1281 rcu_read_lock();
1282 xas_for_each(&xas, folio, ULONG_MAX) {
1283 if (xas_retry(&xas, folio))
1284 continue;
1285
1286 if (!xa_is_value(folio))
1287 continue;
1288
1289 entry = radix_to_swp_entry(folio);
1290 /*
1291 * swapin error entries can be found in the mapping. But they're
1292 * deliberately ignored here as we've done everything we can do.
1293 */
1294 if (swp_type(entry) != type)
1295 continue;
1296
1297 indices[folio_batch_count(fbatch)] = xas.xa_index;
1298 if (!folio_batch_add(fbatch, folio))
1299 break;
1300
1301 if (need_resched()) {
1302 xas_pause(&xas);
1303 cond_resched_rcu();
1304 }
1305 }
1306 rcu_read_unlock();
1307
1308 return xas.xa_index;
1309}
1310
1311/*
1312 * Move the swapped pages for an inode to page cache. Returns the count
1313 * of pages swapped in, or the error in case of failure.
1314 */
1315static int shmem_unuse_swap_entries(struct inode *inode,
1316 struct folio_batch *fbatch, pgoff_t *indices)
1317{
1318 int i = 0;
1319 int ret = 0;
1320 int error = 0;
1321 struct address_space *mapping = inode->i_mapping;
1322
1323 for (i = 0; i < folio_batch_count(fbatch); i++) {
1324 struct folio *folio = fbatch->folios[i];
1325
1326 if (!xa_is_value(folio))
1327 continue;
1328 error = shmem_swapin_folio(inode, indices[i], &folio, SGP_CACHE,
1329 mapping_gfp_mask(mapping), NULL, NULL);
1330 if (error == 0) {
1331 folio_unlock(folio);
1332 folio_put(folio);
1333 ret++;
1334 }
1335 if (error == -ENOMEM)
1336 break;
1337 error = 0;
1338 }
1339 return error ? error : ret;
1340}
1341
1342/*
1343 * If swap found in inode, free it and move page from swapcache to filecache.
1344 */
1345static int shmem_unuse_inode(struct inode *inode, unsigned int type)
1346{
1347 struct address_space *mapping = inode->i_mapping;
1348 pgoff_t start = 0;
1349 struct folio_batch fbatch;
1350 pgoff_t indices[PAGEVEC_SIZE];
1351 int ret = 0;
1352
1353 do {
1354 folio_batch_init(&fbatch);
1355 shmem_find_swap_entries(mapping, start, &fbatch, indices, type);
1356 if (folio_batch_count(&fbatch) == 0) {
1357 ret = 0;
1358 break;
1359 }
1360
1361 ret = shmem_unuse_swap_entries(inode, &fbatch, indices);
1362 if (ret < 0)
1363 break;
1364
1365 start = indices[folio_batch_count(&fbatch) - 1];
1366 } while (true);
1367
1368 return ret;
1369}
1370
1371/*
1372 * Read all the shared memory data that resides in the swap
1373 * device 'type' back into memory, so the swap device can be
1374 * unused.
1375 */
1376int shmem_unuse(unsigned int type)
1377{
1378 struct shmem_inode_info *info, *next;
1379 int error = 0;
1380
1381 if (list_empty(&shmem_swaplist))
1382 return 0;
1383
1384 mutex_lock(&shmem_swaplist_mutex);
1385 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1386 if (!info->swapped) {
1387 list_del_init(&info->swaplist);
1388 continue;
1389 }
1390 /*
1391 * Drop the swaplist mutex while searching the inode for swap;
1392 * but before doing so, make sure shmem_evict_inode() will not
1393 * remove placeholder inode from swaplist, nor let it be freed
1394 * (igrab() would protect from unlink, but not from unmount).
1395 */
1396 atomic_inc(&info->stop_eviction);
1397 mutex_unlock(&shmem_swaplist_mutex);
1398
1399 error = shmem_unuse_inode(&info->vfs_inode, type);
1400 cond_resched();
1401
1402 mutex_lock(&shmem_swaplist_mutex);
1403 next = list_next_entry(info, swaplist);
1404 if (!info->swapped)
1405 list_del_init(&info->swaplist);
1406 if (atomic_dec_and_test(&info->stop_eviction))
1407 wake_up_var(&info->stop_eviction);
1408 if (error)
1409 break;
1410 }
1411 mutex_unlock(&shmem_swaplist_mutex);
1412
1413 return error;
1414}
1415
1416/*
1417 * Move the page from the page cache to the swap cache.
1418 */
1419static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1420{
1421 struct folio *folio = page_folio(page);
1422 struct address_space *mapping = folio->mapping;
1423 struct inode *inode = mapping->host;
1424 struct shmem_inode_info *info = SHMEM_I(inode);
1425 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1426 swp_entry_t swap;
1427 pgoff_t index;
1428
1429 /*
1430 * Our capabilities prevent regular writeback or sync from ever calling
1431 * shmem_writepage; but a stacking filesystem might use ->writepage of
1432 * its underlying filesystem, in which case tmpfs should write out to
1433 * swap only in response to memory pressure, and not for the writeback
1434 * threads or sync.
1435 */
1436 if (WARN_ON_ONCE(!wbc->for_reclaim))
1437 goto redirty;
1438
1439 if (WARN_ON_ONCE((info->flags & VM_LOCKED) || sbinfo->noswap))
1440 goto redirty;
1441
1442 if (!total_swap_pages)
1443 goto redirty;
1444
1445 /*
1446 * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or
1447 * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
1448 * and its shmem_writeback() needs them to be split when swapping.
1449 */
1450 if (folio_test_large(folio)) {
1451 /* Ensure the subpages are still dirty */
1452 folio_test_set_dirty(folio);
1453 if (split_huge_page(page) < 0)
1454 goto redirty;
1455 folio = page_folio(page);
1456 folio_clear_dirty(folio);
1457 }
1458
1459 index = folio->index;
1460
1461 /*
1462 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1463 * value into swapfile.c, the only way we can correctly account for a
1464 * fallocated folio arriving here is now to initialize it and write it.
1465 *
1466 * That's okay for a folio already fallocated earlier, but if we have
1467 * not yet completed the fallocation, then (a) we want to keep track
1468 * of this folio in case we have to undo it, and (b) it may not be a
1469 * good idea to continue anyway, once we're pushing into swap. So
1470 * reactivate the folio, and let shmem_fallocate() quit when too many.
1471 */
1472 if (!folio_test_uptodate(folio)) {
1473 if (inode->i_private) {
1474 struct shmem_falloc *shmem_falloc;
1475 spin_lock(&inode->i_lock);
1476 shmem_falloc = inode->i_private;
1477 if (shmem_falloc &&
1478 !shmem_falloc->waitq &&
1479 index >= shmem_falloc->start &&
1480 index < shmem_falloc->next)
1481 shmem_falloc->nr_unswapped++;
1482 else
1483 shmem_falloc = NULL;
1484 spin_unlock(&inode->i_lock);
1485 if (shmem_falloc)
1486 goto redirty;
1487 }
1488 folio_zero_range(folio, 0, folio_size(folio));
1489 flush_dcache_folio(folio);
1490 folio_mark_uptodate(folio);
1491 }
1492
1493 swap = folio_alloc_swap(folio);
1494 if (!swap.val)
1495 goto redirty;
1496
1497 /*
1498 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1499 * if it's not already there. Do it now before the folio is
1500 * moved to swap cache, when its pagelock no longer protects
1501 * the inode from eviction. But don't unlock the mutex until
1502 * we've incremented swapped, because shmem_unuse_inode() will
1503 * prune a !swapped inode from the swaplist under this mutex.
1504 */
1505 mutex_lock(&shmem_swaplist_mutex);
1506 if (list_empty(&info->swaplist))
1507 list_add(&info->swaplist, &shmem_swaplist);
1508
1509 if (add_to_swap_cache(folio, swap,
1510 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1511 NULL) == 0) {
1512 shmem_recalc_inode(inode, 0, 1);
1513 swap_shmem_alloc(swap);
1514 shmem_delete_from_page_cache(folio, swp_to_radix_entry(swap));
1515
1516 mutex_unlock(&shmem_swaplist_mutex);
1517 BUG_ON(folio_mapped(folio));
1518 return swap_writepage(&folio->page, wbc);
1519 }
1520
1521 mutex_unlock(&shmem_swaplist_mutex);
1522 put_swap_folio(folio, swap);
1523redirty:
1524 folio_mark_dirty(folio);
1525 if (wbc->for_reclaim)
1526 return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */
1527 folio_unlock(folio);
1528 return 0;
1529}
1530
1531#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1532static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1533{
1534 char buffer[64];
1535
1536 if (!mpol || mpol->mode == MPOL_DEFAULT)
1537 return; /* show nothing */
1538
1539 mpol_to_str(buffer, sizeof(buffer), mpol);
1540
1541 seq_printf(seq, ",mpol=%s", buffer);
1542}
1543
1544static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1545{
1546 struct mempolicy *mpol = NULL;
1547 if (sbinfo->mpol) {
1548 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1549 mpol = sbinfo->mpol;
1550 mpol_get(mpol);
1551 raw_spin_unlock(&sbinfo->stat_lock);
1552 }
1553 return mpol;
1554}
1555#else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1556static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1557{
1558}
1559static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1560{
1561 return NULL;
1562}
1563#endif /* CONFIG_NUMA && CONFIG_TMPFS */
1564
1565static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
1566 pgoff_t index, unsigned int order, pgoff_t *ilx);
1567
1568static struct folio *shmem_swapin_cluster(swp_entry_t swap, gfp_t gfp,
1569 struct shmem_inode_info *info, pgoff_t index)
1570{
1571 struct mempolicy *mpol;
1572 pgoff_t ilx;
1573 struct folio *folio;
1574
1575 mpol = shmem_get_pgoff_policy(info, index, 0, &ilx);
1576 folio = swap_cluster_readahead(swap, gfp, mpol, ilx);
1577 mpol_cond_put(mpol);
1578
1579 return folio;
1580}
1581
1582/*
1583 * Make sure huge_gfp is always more limited than limit_gfp.
1584 * Some of the flags set permissions, while others set limitations.
1585 */
1586static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1587{
1588 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1589 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1590 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1591 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1592
1593 /* Allow allocations only from the originally specified zones. */
1594 result |= zoneflags;
1595
1596 /*
1597 * Minimize the result gfp by taking the union with the deny flags,
1598 * and the intersection of the allow flags.
1599 */
1600 result |= (limit_gfp & denyflags);
1601 result |= (huge_gfp & limit_gfp) & allowflags;
1602
1603 return result;
1604}
1605
1606static struct folio *shmem_alloc_hugefolio(gfp_t gfp,
1607 struct shmem_inode_info *info, pgoff_t index)
1608{
1609 struct mempolicy *mpol;
1610 pgoff_t ilx;
1611 struct page *page;
1612
1613 mpol = shmem_get_pgoff_policy(info, index, HPAGE_PMD_ORDER, &ilx);
1614 page = alloc_pages_mpol(gfp, HPAGE_PMD_ORDER, mpol, ilx, numa_node_id());
1615 mpol_cond_put(mpol);
1616
1617 return page_rmappable_folio(page);
1618}
1619
1620static struct folio *shmem_alloc_folio(gfp_t gfp,
1621 struct shmem_inode_info *info, pgoff_t index)
1622{
1623 struct mempolicy *mpol;
1624 pgoff_t ilx;
1625 struct page *page;
1626
1627 mpol = shmem_get_pgoff_policy(info, index, 0, &ilx);
1628 page = alloc_pages_mpol(gfp, 0, mpol, ilx, numa_node_id());
1629 mpol_cond_put(mpol);
1630
1631 return (struct folio *)page;
1632}
1633
1634static struct folio *shmem_alloc_and_add_folio(gfp_t gfp,
1635 struct inode *inode, pgoff_t index,
1636 struct mm_struct *fault_mm, bool huge)
1637{
1638 struct address_space *mapping = inode->i_mapping;
1639 struct shmem_inode_info *info = SHMEM_I(inode);
1640 struct folio *folio;
1641 long pages;
1642 int error;
1643
1644 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1645 huge = false;
1646
1647 if (huge) {
1648 pages = HPAGE_PMD_NR;
1649 index = round_down(index, HPAGE_PMD_NR);
1650
1651 /*
1652 * Check for conflict before waiting on a huge allocation.
1653 * Conflict might be that a huge page has just been allocated
1654 * and added to page cache by a racing thread, or that there
1655 * is already at least one small page in the huge extent.
1656 * Be careful to retry when appropriate, but not forever!
1657 * Elsewhere -EEXIST would be the right code, but not here.
1658 */
1659 if (xa_find(&mapping->i_pages, &index,
1660 index + HPAGE_PMD_NR - 1, XA_PRESENT))
1661 return ERR_PTR(-E2BIG);
1662
1663 folio = shmem_alloc_hugefolio(gfp, info, index);
1664 if (!folio)
1665 count_vm_event(THP_FILE_FALLBACK);
1666 } else {
1667 pages = 1;
1668 folio = shmem_alloc_folio(gfp, info, index);
1669 }
1670 if (!folio)
1671 return ERR_PTR(-ENOMEM);
1672
1673 __folio_set_locked(folio);
1674 __folio_set_swapbacked(folio);
1675
1676 gfp &= GFP_RECLAIM_MASK;
1677 error = mem_cgroup_charge(folio, fault_mm, gfp);
1678 if (error) {
1679 if (xa_find(&mapping->i_pages, &index,
1680 index + pages - 1, XA_PRESENT)) {
1681 error = -EEXIST;
1682 } else if (huge) {
1683 count_vm_event(THP_FILE_FALLBACK);
1684 count_vm_event(THP_FILE_FALLBACK_CHARGE);
1685 }
1686 goto unlock;
1687 }
1688
1689 error = shmem_add_to_page_cache(folio, mapping, index, NULL, gfp);
1690 if (error)
1691 goto unlock;
1692
1693 error = shmem_inode_acct_blocks(inode, pages);
1694 if (error) {
1695 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1696 long freed;
1697 /*
1698 * Try to reclaim some space by splitting a few
1699 * large folios beyond i_size on the filesystem.
1700 */
1701 shmem_unused_huge_shrink(sbinfo, NULL, 2);
1702 /*
1703 * And do a shmem_recalc_inode() to account for freed pages:
1704 * except our folio is there in cache, so not quite balanced.
1705 */
1706 spin_lock(&info->lock);
1707 freed = pages + info->alloced - info->swapped -
1708 READ_ONCE(mapping->nrpages);
1709 if (freed > 0)
1710 info->alloced -= freed;
1711 spin_unlock(&info->lock);
1712 if (freed > 0)
1713 shmem_inode_unacct_blocks(inode, freed);
1714 error = shmem_inode_acct_blocks(inode, pages);
1715 if (error) {
1716 filemap_remove_folio(folio);
1717 goto unlock;
1718 }
1719 }
1720
1721 shmem_recalc_inode(inode, pages, 0);
1722 folio_add_lru(folio);
1723 return folio;
1724
1725unlock:
1726 folio_unlock(folio);
1727 folio_put(folio);
1728 return ERR_PTR(error);
1729}
1730
1731/*
1732 * When a page is moved from swapcache to shmem filecache (either by the
1733 * usual swapin of shmem_get_folio_gfp(), or by the less common swapoff of
1734 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1735 * ignorance of the mapping it belongs to. If that mapping has special
1736 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1737 * we may need to copy to a suitable page before moving to filecache.
1738 *
1739 * In a future release, this may well be extended to respect cpuset and
1740 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1741 * but for now it is a simple matter of zone.
1742 */
1743static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
1744{
1745 return folio_zonenum(folio) > gfp_zone(gfp);
1746}
1747
1748static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
1749 struct shmem_inode_info *info, pgoff_t index)
1750{
1751 struct folio *old, *new;
1752 struct address_space *swap_mapping;
1753 swp_entry_t entry;
1754 pgoff_t swap_index;
1755 int error;
1756
1757 old = *foliop;
1758 entry = old->swap;
1759 swap_index = swp_offset(entry);
1760 swap_mapping = swap_address_space(entry);
1761
1762 /*
1763 * We have arrived here because our zones are constrained, so don't
1764 * limit chance of success by further cpuset and node constraints.
1765 */
1766 gfp &= ~GFP_CONSTRAINT_MASK;
1767 VM_BUG_ON_FOLIO(folio_test_large(old), old);
1768 new = shmem_alloc_folio(gfp, info, index);
1769 if (!new)
1770 return -ENOMEM;
1771
1772 folio_get(new);
1773 folio_copy(new, old);
1774 flush_dcache_folio(new);
1775
1776 __folio_set_locked(new);
1777 __folio_set_swapbacked(new);
1778 folio_mark_uptodate(new);
1779 new->swap = entry;
1780 folio_set_swapcache(new);
1781
1782 /*
1783 * Our caller will very soon move newpage out of swapcache, but it's
1784 * a nice clean interface for us to replace oldpage by newpage there.
1785 */
1786 xa_lock_irq(&swap_mapping->i_pages);
1787 error = shmem_replace_entry(swap_mapping, swap_index, old, new);
1788 if (!error) {
1789 mem_cgroup_migrate(old, new);
1790 __lruvec_stat_mod_folio(new, NR_FILE_PAGES, 1);
1791 __lruvec_stat_mod_folio(new, NR_SHMEM, 1);
1792 __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -1);
1793 __lruvec_stat_mod_folio(old, NR_SHMEM, -1);
1794 }
1795 xa_unlock_irq(&swap_mapping->i_pages);
1796
1797 if (unlikely(error)) {
1798 /*
1799 * Is this possible? I think not, now that our callers check
1800 * both PageSwapCache and page_private after getting page lock;
1801 * but be defensive. Reverse old to newpage for clear and free.
1802 */
1803 old = new;
1804 } else {
1805 folio_add_lru(new);
1806 *foliop = new;
1807 }
1808
1809 folio_clear_swapcache(old);
1810 old->private = NULL;
1811
1812 folio_unlock(old);
1813 folio_put_refs(old, 2);
1814 return error;
1815}
1816
1817static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
1818 struct folio *folio, swp_entry_t swap)
1819{
1820 struct address_space *mapping = inode->i_mapping;
1821 swp_entry_t swapin_error;
1822 void *old;
1823
1824 swapin_error = make_poisoned_swp_entry();
1825 old = xa_cmpxchg_irq(&mapping->i_pages, index,
1826 swp_to_radix_entry(swap),
1827 swp_to_radix_entry(swapin_error), 0);
1828 if (old != swp_to_radix_entry(swap))
1829 return;
1830
1831 folio_wait_writeback(folio);
1832 delete_from_swap_cache(folio);
1833 /*
1834 * Don't treat swapin error folio as alloced. Otherwise inode->i_blocks
1835 * won't be 0 when inode is released and thus trigger WARN_ON(i_blocks)
1836 * in shmem_evict_inode().
1837 */
1838 shmem_recalc_inode(inode, -1, -1);
1839 swap_free(swap);
1840}
1841
1842/*
1843 * Swap in the folio pointed to by *foliop.
1844 * Caller has to make sure that *foliop contains a valid swapped folio.
1845 * Returns 0 and the folio in foliop if success. On failure, returns the
1846 * error code and NULL in *foliop.
1847 */
1848static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
1849 struct folio **foliop, enum sgp_type sgp,
1850 gfp_t gfp, struct mm_struct *fault_mm,
1851 vm_fault_t *fault_type)
1852{
1853 struct address_space *mapping = inode->i_mapping;
1854 struct shmem_inode_info *info = SHMEM_I(inode);
1855 struct swap_info_struct *si;
1856 struct folio *folio = NULL;
1857 swp_entry_t swap;
1858 int error;
1859
1860 VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
1861 swap = radix_to_swp_entry(*foliop);
1862 *foliop = NULL;
1863
1864 if (is_poisoned_swp_entry(swap))
1865 return -EIO;
1866
1867 si = get_swap_device(swap);
1868 if (!si) {
1869 if (!shmem_confirm_swap(mapping, index, swap))
1870 return -EEXIST;
1871 else
1872 return -EINVAL;
1873 }
1874
1875 /* Look it up and read it in.. */
1876 folio = swap_cache_get_folio(swap, NULL, 0);
1877 if (!folio) {
1878 /* Or update major stats only when swapin succeeds?? */
1879 if (fault_type) {
1880 *fault_type |= VM_FAULT_MAJOR;
1881 count_vm_event(PGMAJFAULT);
1882 count_memcg_event_mm(fault_mm, PGMAJFAULT);
1883 }
1884 /* Here we actually start the io */
1885 folio = shmem_swapin_cluster(swap, gfp, info, index);
1886 if (!folio) {
1887 error = -ENOMEM;
1888 goto failed;
1889 }
1890 }
1891
1892 /* We have to do this with folio locked to prevent races */
1893 folio_lock(folio);
1894 if (!folio_test_swapcache(folio) ||
1895 folio->swap.val != swap.val ||
1896 !shmem_confirm_swap(mapping, index, swap)) {
1897 error = -EEXIST;
1898 goto unlock;
1899 }
1900 if (!folio_test_uptodate(folio)) {
1901 error = -EIO;
1902 goto failed;
1903 }
1904 folio_wait_writeback(folio);
1905
1906 /*
1907 * Some architectures may have to restore extra metadata to the
1908 * folio after reading from swap.
1909 */
1910 arch_swap_restore(swap, folio);
1911
1912 if (shmem_should_replace_folio(folio, gfp)) {
1913 error = shmem_replace_folio(&folio, gfp, info, index);
1914 if (error)
1915 goto failed;
1916 }
1917
1918 error = shmem_add_to_page_cache(folio, mapping, index,
1919 swp_to_radix_entry(swap), gfp);
1920 if (error)
1921 goto failed;
1922
1923 shmem_recalc_inode(inode, 0, -1);
1924
1925 if (sgp == SGP_WRITE)
1926 folio_mark_accessed(folio);
1927
1928 delete_from_swap_cache(folio);
1929 folio_mark_dirty(folio);
1930 swap_free(swap);
1931 put_swap_device(si);
1932
1933 *foliop = folio;
1934 return 0;
1935failed:
1936 if (!shmem_confirm_swap(mapping, index, swap))
1937 error = -EEXIST;
1938 if (error == -EIO)
1939 shmem_set_folio_swapin_error(inode, index, folio, swap);
1940unlock:
1941 if (folio) {
1942 folio_unlock(folio);
1943 folio_put(folio);
1944 }
1945 put_swap_device(si);
1946
1947 return error;
1948}
1949
1950/*
1951 * shmem_get_folio_gfp - find page in cache, or get from swap, or allocate
1952 *
1953 * If we allocate a new one we do not mark it dirty. That's up to the
1954 * vm. If we swap it in we mark it dirty since we also free the swap
1955 * entry since a page cannot live in both the swap and page cache.
1956 *
1957 * vmf and fault_type are only supplied by shmem_fault: otherwise they are NULL.
1958 */
1959static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
1960 struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
1961 struct vm_fault *vmf, vm_fault_t *fault_type)
1962{
1963 struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
1964 struct mm_struct *fault_mm;
1965 struct folio *folio;
1966 int error;
1967 bool alloced;
1968
1969 if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
1970 return -EINVAL;
1971
1972 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1973 return -EFBIG;
1974repeat:
1975 if (sgp <= SGP_CACHE &&
1976 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode))
1977 return -EINVAL;
1978
1979 alloced = false;
1980 fault_mm = vma ? vma->vm_mm : NULL;
1981
1982 folio = filemap_get_entry(inode->i_mapping, index);
1983 if (folio && vma && userfaultfd_minor(vma)) {
1984 if (!xa_is_value(folio))
1985 folio_put(folio);
1986 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
1987 return 0;
1988 }
1989
1990 if (xa_is_value(folio)) {
1991 error = shmem_swapin_folio(inode, index, &folio,
1992 sgp, gfp, fault_mm, fault_type);
1993 if (error == -EEXIST)
1994 goto repeat;
1995
1996 *foliop = folio;
1997 return error;
1998 }
1999
2000 if (folio) {
2001 folio_lock(folio);
2002
2003 /* Has the folio been truncated or swapped out? */
2004 if (unlikely(folio->mapping != inode->i_mapping)) {
2005 folio_unlock(folio);
2006 folio_put(folio);
2007 goto repeat;
2008 }
2009 if (sgp == SGP_WRITE)
2010 folio_mark_accessed(folio);
2011 if (folio_test_uptodate(folio))
2012 goto out;
2013 /* fallocated folio */
2014 if (sgp != SGP_READ)
2015 goto clear;
2016 folio_unlock(folio);
2017 folio_put(folio);
2018 }
2019
2020 /*
2021 * SGP_READ: succeed on hole, with NULL folio, letting caller zero.
2022 * SGP_NOALLOC: fail on hole, with NULL folio, letting caller fail.
2023 */
2024 *foliop = NULL;
2025 if (sgp == SGP_READ)
2026 return 0;
2027 if (sgp == SGP_NOALLOC)
2028 return -ENOENT;
2029
2030 /*
2031 * Fast cache lookup and swap lookup did not find it: allocate.
2032 */
2033
2034 if (vma && userfaultfd_missing(vma)) {
2035 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
2036 return 0;
2037 }
2038
2039 if (shmem_is_huge(inode, index, false, fault_mm,
2040 vma ? vma->vm_flags : 0)) {
2041 gfp_t huge_gfp;
2042
2043 huge_gfp = vma_thp_gfp_mask(vma);
2044 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
2045 folio = shmem_alloc_and_add_folio(huge_gfp,
2046 inode, index, fault_mm, true);
2047 if (!IS_ERR(folio)) {
2048 count_vm_event(THP_FILE_ALLOC);
2049 goto alloced;
2050 }
2051 if (PTR_ERR(folio) == -EEXIST)
2052 goto repeat;
2053 }
2054
2055 folio = shmem_alloc_and_add_folio(gfp, inode, index, fault_mm, false);
2056 if (IS_ERR(folio)) {
2057 error = PTR_ERR(folio);
2058 if (error == -EEXIST)
2059 goto repeat;
2060 folio = NULL;
2061 goto unlock;
2062 }
2063
2064alloced:
2065 alloced = true;
2066 if (folio_test_pmd_mappable(folio) &&
2067 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
2068 folio_next_index(folio) - 1) {
2069 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2070 struct shmem_inode_info *info = SHMEM_I(inode);
2071 /*
2072 * Part of the large folio is beyond i_size: subject
2073 * to shrink under memory pressure.
2074 */
2075 spin_lock(&sbinfo->shrinklist_lock);
2076 /*
2077 * _careful to defend against unlocked access to
2078 * ->shrink_list in shmem_unused_huge_shrink()
2079 */
2080 if (list_empty_careful(&info->shrinklist)) {
2081 list_add_tail(&info->shrinklist,
2082 &sbinfo->shrinklist);
2083 sbinfo->shrinklist_len++;
2084 }
2085 spin_unlock(&sbinfo->shrinklist_lock);
2086 }
2087
2088 if (sgp == SGP_WRITE)
2089 folio_set_referenced(folio);
2090 /*
2091 * Let SGP_FALLOC use the SGP_WRITE optimization on a new folio.
2092 */
2093 if (sgp == SGP_FALLOC)
2094 sgp = SGP_WRITE;
2095clear:
2096 /*
2097 * Let SGP_WRITE caller clear ends if write does not fill folio;
2098 * but SGP_FALLOC on a folio fallocated earlier must initialize
2099 * it now, lest undo on failure cancel our earlier guarantee.
2100 */
2101 if (sgp != SGP_WRITE && !folio_test_uptodate(folio)) {
2102 long i, n = folio_nr_pages(folio);
2103
2104 for (i = 0; i < n; i++)
2105 clear_highpage(folio_page(folio, i));
2106 flush_dcache_folio(folio);
2107 folio_mark_uptodate(folio);
2108 }
2109
2110 /* Perhaps the file has been truncated since we checked */
2111 if (sgp <= SGP_CACHE &&
2112 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
2113 error = -EINVAL;
2114 goto unlock;
2115 }
2116out:
2117 *foliop = folio;
2118 return 0;
2119
2120 /*
2121 * Error recovery.
2122 */
2123unlock:
2124 if (alloced)
2125 filemap_remove_folio(folio);
2126 shmem_recalc_inode(inode, 0, 0);
2127 if (folio) {
2128 folio_unlock(folio);
2129 folio_put(folio);
2130 }
2131 return error;
2132}
2133
2134/**
2135 * shmem_get_folio - find, and lock a shmem folio.
2136 * @inode: inode to search
2137 * @index: the page index.
2138 * @foliop: pointer to the folio if found
2139 * @sgp: SGP_* flags to control behavior
2140 *
2141 * Looks up the page cache entry at @inode & @index. If a folio is
2142 * present, it is returned locked with an increased refcount.
2143 *
2144 * If the caller modifies data in the folio, it must call folio_mark_dirty()
2145 * before unlocking the folio to ensure that the folio is not reclaimed.
2146 * There is no need to reserve space before calling folio_mark_dirty().
2147 *
2148 * When no folio is found, the behavior depends on @sgp:
2149 * - for SGP_READ, *@foliop is %NULL and 0 is returned
2150 * - for SGP_NOALLOC, *@foliop is %NULL and -ENOENT is returned
2151 * - for all other flags a new folio is allocated, inserted into the
2152 * page cache and returned locked in @foliop.
2153 *
2154 * Context: May sleep.
2155 * Return: 0 if successful, else a negative error code.
2156 */
2157int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
2158 enum sgp_type sgp)
2159{
2160 return shmem_get_folio_gfp(inode, index, foliop, sgp,
2161 mapping_gfp_mask(inode->i_mapping), NULL, NULL);
2162}
2163EXPORT_SYMBOL_GPL(shmem_get_folio);
2164
2165/*
2166 * This is like autoremove_wake_function, but it removes the wait queue
2167 * entry unconditionally - even if something else had already woken the
2168 * target.
2169 */
2170static int synchronous_wake_function(wait_queue_entry_t *wait,
2171 unsigned int mode, int sync, void *key)
2172{
2173 int ret = default_wake_function(wait, mode, sync, key);
2174 list_del_init(&wait->entry);
2175 return ret;
2176}
2177
2178/*
2179 * Trinity finds that probing a hole which tmpfs is punching can
2180 * prevent the hole-punch from ever completing: which in turn
2181 * locks writers out with its hold on i_rwsem. So refrain from
2182 * faulting pages into the hole while it's being punched. Although
2183 * shmem_undo_range() does remove the additions, it may be unable to
2184 * keep up, as each new page needs its own unmap_mapping_range() call,
2185 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2186 *
2187 * It does not matter if we sometimes reach this check just before the
2188 * hole-punch begins, so that one fault then races with the punch:
2189 * we just need to make racing faults a rare case.
2190 *
2191 * The implementation below would be much simpler if we just used a
2192 * standard mutex or completion: but we cannot take i_rwsem in fault,
2193 * and bloating every shmem inode for this unlikely case would be sad.
2194 */
2195static vm_fault_t shmem_falloc_wait(struct vm_fault *vmf, struct inode *inode)
2196{
2197 struct shmem_falloc *shmem_falloc;
2198 struct file *fpin = NULL;
2199 vm_fault_t ret = 0;
2200
2201 spin_lock(&inode->i_lock);
2202 shmem_falloc = inode->i_private;
2203 if (shmem_falloc &&
2204 shmem_falloc->waitq &&
2205 vmf->pgoff >= shmem_falloc->start &&
2206 vmf->pgoff < shmem_falloc->next) {
2207 wait_queue_head_t *shmem_falloc_waitq;
2208 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2209
2210 ret = VM_FAULT_NOPAGE;
2211 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2212 shmem_falloc_waitq = shmem_falloc->waitq;
2213 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2214 TASK_UNINTERRUPTIBLE);
2215 spin_unlock(&inode->i_lock);
2216 schedule();
2217
2218 /*
2219 * shmem_falloc_waitq points into the shmem_fallocate()
2220 * stack of the hole-punching task: shmem_falloc_waitq
2221 * is usually invalid by the time we reach here, but
2222 * finish_wait() does not dereference it in that case;
2223 * though i_lock needed lest racing with wake_up_all().
2224 */
2225 spin_lock(&inode->i_lock);
2226 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2227 }
2228 spin_unlock(&inode->i_lock);
2229 if (fpin) {
2230 fput(fpin);
2231 ret = VM_FAULT_RETRY;
2232 }
2233 return ret;
2234}
2235
2236static vm_fault_t shmem_fault(struct vm_fault *vmf)
2237{
2238 struct inode *inode = file_inode(vmf->vma->vm_file);
2239 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2240 struct folio *folio = NULL;
2241 vm_fault_t ret = 0;
2242 int err;
2243
2244 /*
2245 * Trinity finds that probing a hole which tmpfs is punching can
2246 * prevent the hole-punch from ever completing: noted in i_private.
2247 */
2248 if (unlikely(inode->i_private)) {
2249 ret = shmem_falloc_wait(vmf, inode);
2250 if (ret)
2251 return ret;
2252 }
2253
2254 WARN_ON_ONCE(vmf->page != NULL);
2255 err = shmem_get_folio_gfp(inode, vmf->pgoff, &folio, SGP_CACHE,
2256 gfp, vmf, &ret);
2257 if (err)
2258 return vmf_error(err);
2259 if (folio) {
2260 vmf->page = folio_file_page(folio, vmf->pgoff);
2261 ret |= VM_FAULT_LOCKED;
2262 }
2263 return ret;
2264}
2265
2266unsigned long shmem_get_unmapped_area(struct file *file,
2267 unsigned long uaddr, unsigned long len,
2268 unsigned long pgoff, unsigned long flags)
2269{
2270 unsigned long (*get_area)(struct file *,
2271 unsigned long, unsigned long, unsigned long, unsigned long);
2272 unsigned long addr;
2273 unsigned long offset;
2274 unsigned long inflated_len;
2275 unsigned long inflated_addr;
2276 unsigned long inflated_offset;
2277
2278 if (len > TASK_SIZE)
2279 return -ENOMEM;
2280
2281 get_area = current->mm->get_unmapped_area;
2282 addr = get_area(file, uaddr, len, pgoff, flags);
2283
2284 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2285 return addr;
2286 if (IS_ERR_VALUE(addr))
2287 return addr;
2288 if (addr & ~PAGE_MASK)
2289 return addr;
2290 if (addr > TASK_SIZE - len)
2291 return addr;
2292
2293 if (shmem_huge == SHMEM_HUGE_DENY)
2294 return addr;
2295 if (len < HPAGE_PMD_SIZE)
2296 return addr;
2297 if (flags & MAP_FIXED)
2298 return addr;
2299 /*
2300 * Our priority is to support MAP_SHARED mapped hugely;
2301 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2302 * But if caller specified an address hint and we allocated area there
2303 * successfully, respect that as before.
2304 */
2305 if (uaddr == addr)
2306 return addr;
2307
2308 if (shmem_huge != SHMEM_HUGE_FORCE) {
2309 struct super_block *sb;
2310
2311 if (file) {
2312 VM_BUG_ON(file->f_op != &shmem_file_operations);
2313 sb = file_inode(file)->i_sb;
2314 } else {
2315 /*
2316 * Called directly from mm/mmap.c, or drivers/char/mem.c
2317 * for "/dev/zero", to create a shared anonymous object.
2318 */
2319 if (IS_ERR(shm_mnt))
2320 return addr;
2321 sb = shm_mnt->mnt_sb;
2322 }
2323 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2324 return addr;
2325 }
2326
2327 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2328 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2329 return addr;
2330 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2331 return addr;
2332
2333 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2334 if (inflated_len > TASK_SIZE)
2335 return addr;
2336 if (inflated_len < len)
2337 return addr;
2338
2339 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2340 if (IS_ERR_VALUE(inflated_addr))
2341 return addr;
2342 if (inflated_addr & ~PAGE_MASK)
2343 return addr;
2344
2345 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2346 inflated_addr += offset - inflated_offset;
2347 if (inflated_offset > offset)
2348 inflated_addr += HPAGE_PMD_SIZE;
2349
2350 if (inflated_addr > TASK_SIZE - len)
2351 return addr;
2352 return inflated_addr;
2353}
2354
2355#ifdef CONFIG_NUMA
2356static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2357{
2358 struct inode *inode = file_inode(vma->vm_file);
2359 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2360}
2361
2362static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2363 unsigned long addr, pgoff_t *ilx)
2364{
2365 struct inode *inode = file_inode(vma->vm_file);
2366 pgoff_t index;
2367
2368 /*
2369 * Bias interleave by inode number to distribute better across nodes;
2370 * but this interface is independent of which page order is used, so
2371 * supplies only that bias, letting caller apply the offset (adjusted
2372 * by page order, as in shmem_get_pgoff_policy() and get_vma_policy()).
2373 */
2374 *ilx = inode->i_ino;
2375 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2376 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2377}
2378
2379static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
2380 pgoff_t index, unsigned int order, pgoff_t *ilx)
2381{
2382 struct mempolicy *mpol;
2383
2384 /* Bias interleave by inode number to distribute better across nodes */
2385 *ilx = info->vfs_inode.i_ino + (index >> order);
2386
2387 mpol = mpol_shared_policy_lookup(&info->policy, index);
2388 return mpol ? mpol : get_task_policy(current);
2389}
2390#else
2391static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
2392 pgoff_t index, unsigned int order, pgoff_t *ilx)
2393{
2394 *ilx = 0;
2395 return NULL;
2396}
2397#endif /* CONFIG_NUMA */
2398
2399int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2400{
2401 struct inode *inode = file_inode(file);
2402 struct shmem_inode_info *info = SHMEM_I(inode);
2403 int retval = -ENOMEM;
2404
2405 /*
2406 * What serializes the accesses to info->flags?
2407 * ipc_lock_object() when called from shmctl_do_lock(),
2408 * no serialization needed when called from shm_destroy().
2409 */
2410 if (lock && !(info->flags & VM_LOCKED)) {
2411 if (!user_shm_lock(inode->i_size, ucounts))
2412 goto out_nomem;
2413 info->flags |= VM_LOCKED;
2414 mapping_set_unevictable(file->f_mapping);
2415 }
2416 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2417 user_shm_unlock(inode->i_size, ucounts);
2418 info->flags &= ~VM_LOCKED;
2419 mapping_clear_unevictable(file->f_mapping);
2420 }
2421 retval = 0;
2422
2423out_nomem:
2424 return retval;
2425}
2426
2427static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2428{
2429 struct inode *inode = file_inode(file);
2430 struct shmem_inode_info *info = SHMEM_I(inode);
2431 int ret;
2432
2433 ret = seal_check_write(info->seals, vma);
2434 if (ret)
2435 return ret;
2436
2437 /* arm64 - allow memory tagging on RAM-based files */
2438 vm_flags_set(vma, VM_MTE_ALLOWED);
2439
2440 file_accessed(file);
2441 /* This is anonymous shared memory if it is unlinked at the time of mmap */
2442 if (inode->i_nlink)
2443 vma->vm_ops = &shmem_vm_ops;
2444 else
2445 vma->vm_ops = &shmem_anon_vm_ops;
2446 return 0;
2447}
2448
2449static int shmem_file_open(struct inode *inode, struct file *file)
2450{
2451 file->f_mode |= FMODE_CAN_ODIRECT;
2452 return generic_file_open(inode, file);
2453}
2454
2455#ifdef CONFIG_TMPFS_XATTR
2456static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2457
2458/*
2459 * chattr's fsflags are unrelated to extended attributes,
2460 * but tmpfs has chosen to enable them under the same config option.
2461 */
2462static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags)
2463{
2464 unsigned int i_flags = 0;
2465
2466 if (fsflags & FS_NOATIME_FL)
2467 i_flags |= S_NOATIME;
2468 if (fsflags & FS_APPEND_FL)
2469 i_flags |= S_APPEND;
2470 if (fsflags & FS_IMMUTABLE_FL)
2471 i_flags |= S_IMMUTABLE;
2472 /*
2473 * But FS_NODUMP_FL does not require any action in i_flags.
2474 */
2475 inode_set_flags(inode, i_flags, S_NOATIME | S_APPEND | S_IMMUTABLE);
2476}
2477#else
2478static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags)
2479{
2480}
2481#define shmem_initxattrs NULL
2482#endif
2483
2484static struct offset_ctx *shmem_get_offset_ctx(struct inode *inode)
2485{
2486 return &SHMEM_I(inode)->dir_offsets;
2487}
2488
2489static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
2490 struct super_block *sb,
2491 struct inode *dir, umode_t mode,
2492 dev_t dev, unsigned long flags)
2493{
2494 struct inode *inode;
2495 struct shmem_inode_info *info;
2496 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2497 ino_t ino;
2498 int err;
2499
2500 err = shmem_reserve_inode(sb, &ino);
2501 if (err)
2502 return ERR_PTR(err);
2503
2504 inode = new_inode(sb);
2505 if (!inode) {
2506 shmem_free_inode(sb, 0);
2507 return ERR_PTR(-ENOSPC);
2508 }
2509
2510 inode->i_ino = ino;
2511 inode_init_owner(idmap, inode, dir, mode);
2512 inode->i_blocks = 0;
2513 simple_inode_init_ts(inode);
2514 inode->i_generation = get_random_u32();
2515 info = SHMEM_I(inode);
2516 memset(info, 0, (char *)inode - (char *)info);
2517 spin_lock_init(&info->lock);
2518 atomic_set(&info->stop_eviction, 0);
2519 info->seals = F_SEAL_SEAL;
2520 info->flags = flags & VM_NORESERVE;
2521 info->i_crtime = inode_get_mtime(inode);
2522 info->fsflags = (dir == NULL) ? 0 :
2523 SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
2524 if (info->fsflags)
2525 shmem_set_inode_flags(inode, info->fsflags);
2526 INIT_LIST_HEAD(&info->shrinklist);
2527 INIT_LIST_HEAD(&info->swaplist);
2528 simple_xattrs_init(&info->xattrs);
2529 cache_no_acl(inode);
2530 if (sbinfo->noswap)
2531 mapping_set_unevictable(inode->i_mapping);
2532 mapping_set_large_folios(inode->i_mapping);
2533
2534 switch (mode & S_IFMT) {
2535 default:
2536 inode->i_op = &shmem_special_inode_operations;
2537 init_special_inode(inode, mode, dev);
2538 break;
2539 case S_IFREG:
2540 inode->i_mapping->a_ops = &shmem_aops;
2541 inode->i_op = &shmem_inode_operations;
2542 inode->i_fop = &shmem_file_operations;
2543 mpol_shared_policy_init(&info->policy,
2544 shmem_get_sbmpol(sbinfo));
2545 break;
2546 case S_IFDIR:
2547 inc_nlink(inode);
2548 /* Some things misbehave if size == 0 on a directory */
2549 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2550 inode->i_op = &shmem_dir_inode_operations;
2551 inode->i_fop = &simple_offset_dir_operations;
2552 simple_offset_init(shmem_get_offset_ctx(inode));
2553 break;
2554 case S_IFLNK:
2555 /*
2556 * Must not load anything in the rbtree,
2557 * mpol_free_shared_policy will not be called.
2558 */
2559 mpol_shared_policy_init(&info->policy, NULL);
2560 break;
2561 }
2562
2563 lockdep_annotate_inode_mutex_key(inode);
2564 return inode;
2565}
2566
2567#ifdef CONFIG_TMPFS_QUOTA
2568static struct inode *shmem_get_inode(struct mnt_idmap *idmap,
2569 struct super_block *sb, struct inode *dir,
2570 umode_t mode, dev_t dev, unsigned long flags)
2571{
2572 int err;
2573 struct inode *inode;
2574
2575 inode = __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
2576 if (IS_ERR(inode))
2577 return inode;
2578
2579 err = dquot_initialize(inode);
2580 if (err)
2581 goto errout;
2582
2583 err = dquot_alloc_inode(inode);
2584 if (err) {
2585 dquot_drop(inode);
2586 goto errout;
2587 }
2588 return inode;
2589
2590errout:
2591 inode->i_flags |= S_NOQUOTA;
2592 iput(inode);
2593 return ERR_PTR(err);
2594}
2595#else
2596static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
2597 struct super_block *sb, struct inode *dir,
2598 umode_t mode, dev_t dev, unsigned long flags)
2599{
2600 return __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
2601}
2602#endif /* CONFIG_TMPFS_QUOTA */
2603
2604#ifdef CONFIG_USERFAULTFD
2605int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
2606 struct vm_area_struct *dst_vma,
2607 unsigned long dst_addr,
2608 unsigned long src_addr,
2609 uffd_flags_t flags,
2610 struct folio **foliop)
2611{
2612 struct inode *inode = file_inode(dst_vma->vm_file);
2613 struct shmem_inode_info *info = SHMEM_I(inode);
2614 struct address_space *mapping = inode->i_mapping;
2615 gfp_t gfp = mapping_gfp_mask(mapping);
2616 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2617 void *page_kaddr;
2618 struct folio *folio;
2619 int ret;
2620 pgoff_t max_off;
2621
2622 if (shmem_inode_acct_blocks(inode, 1)) {
2623 /*
2624 * We may have got a page, returned -ENOENT triggering a retry,
2625 * and now we find ourselves with -ENOMEM. Release the page, to
2626 * avoid a BUG_ON in our caller.
2627 */
2628 if (unlikely(*foliop)) {
2629 folio_put(*foliop);
2630 *foliop = NULL;
2631 }
2632 return -ENOMEM;
2633 }
2634
2635 if (!*foliop) {
2636 ret = -ENOMEM;
2637 folio = shmem_alloc_folio(gfp, info, pgoff);
2638 if (!folio)
2639 goto out_unacct_blocks;
2640
2641 if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) {
2642 page_kaddr = kmap_local_folio(folio, 0);
2643 /*
2644 * The read mmap_lock is held here. Despite the
2645 * mmap_lock being read recursive a deadlock is still
2646 * possible if a writer has taken a lock. For example:
2647 *
2648 * process A thread 1 takes read lock on own mmap_lock
2649 * process A thread 2 calls mmap, blocks taking write lock
2650 * process B thread 1 takes page fault, read lock on own mmap lock
2651 * process B thread 2 calls mmap, blocks taking write lock
2652 * process A thread 1 blocks taking read lock on process B
2653 * process B thread 1 blocks taking read lock on process A
2654 *
2655 * Disable page faults to prevent potential deadlock
2656 * and retry the copy outside the mmap_lock.
2657 */
2658 pagefault_disable();
2659 ret = copy_from_user(page_kaddr,
2660 (const void __user *)src_addr,
2661 PAGE_SIZE);
2662 pagefault_enable();
2663 kunmap_local(page_kaddr);
2664
2665 /* fallback to copy_from_user outside mmap_lock */
2666 if (unlikely(ret)) {
2667 *foliop = folio;
2668 ret = -ENOENT;
2669 /* don't free the page */
2670 goto out_unacct_blocks;
2671 }
2672
2673 flush_dcache_folio(folio);
2674 } else { /* ZEROPAGE */
2675 clear_user_highpage(&folio->page, dst_addr);
2676 }
2677 } else {
2678 folio = *foliop;
2679 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
2680 *foliop = NULL;
2681 }
2682
2683 VM_BUG_ON(folio_test_locked(folio));
2684 VM_BUG_ON(folio_test_swapbacked(folio));
2685 __folio_set_locked(folio);
2686 __folio_set_swapbacked(folio);
2687 __folio_mark_uptodate(folio);
2688
2689 ret = -EFAULT;
2690 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2691 if (unlikely(pgoff >= max_off))
2692 goto out_release;
2693
2694 ret = mem_cgroup_charge(folio, dst_vma->vm_mm, gfp);
2695 if (ret)
2696 goto out_release;
2697 ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL, gfp);
2698 if (ret)
2699 goto out_release;
2700
2701 ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
2702 &folio->page, true, flags);
2703 if (ret)
2704 goto out_delete_from_cache;
2705
2706 shmem_recalc_inode(inode, 1, 0);
2707 folio_unlock(folio);
2708 return 0;
2709out_delete_from_cache:
2710 filemap_remove_folio(folio);
2711out_release:
2712 folio_unlock(folio);
2713 folio_put(folio);
2714out_unacct_blocks:
2715 shmem_inode_unacct_blocks(inode, 1);
2716 return ret;
2717}
2718#endif /* CONFIG_USERFAULTFD */
2719
2720#ifdef CONFIG_TMPFS
2721static const struct inode_operations shmem_symlink_inode_operations;
2722static const struct inode_operations shmem_short_symlink_operations;
2723
2724static int
2725shmem_write_begin(struct file *file, struct address_space *mapping,
2726 loff_t pos, unsigned len,
2727 struct page **pagep, void **fsdata)
2728{
2729 struct inode *inode = mapping->host;
2730 struct shmem_inode_info *info = SHMEM_I(inode);
2731 pgoff_t index = pos >> PAGE_SHIFT;
2732 struct folio *folio;
2733 int ret = 0;
2734
2735 /* i_rwsem is held by caller */
2736 if (unlikely(info->seals & (F_SEAL_GROW |
2737 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2738 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2739 return -EPERM;
2740 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2741 return -EPERM;
2742 }
2743
2744 ret = shmem_get_folio(inode, index, &folio, SGP_WRITE);
2745 if (ret)
2746 return ret;
2747
2748 *pagep = folio_file_page(folio, index);
2749 if (PageHWPoison(*pagep)) {
2750 folio_unlock(folio);
2751 folio_put(folio);
2752 *pagep = NULL;
2753 return -EIO;
2754 }
2755
2756 return 0;
2757}
2758
2759static int
2760shmem_write_end(struct file *file, struct address_space *mapping,
2761 loff_t pos, unsigned len, unsigned copied,
2762 struct page *page, void *fsdata)
2763{
2764 struct folio *folio = page_folio(page);
2765 struct inode *inode = mapping->host;
2766
2767 if (pos + copied > inode->i_size)
2768 i_size_write(inode, pos + copied);
2769
2770 if (!folio_test_uptodate(folio)) {
2771 if (copied < folio_size(folio)) {
2772 size_t from = offset_in_folio(folio, pos);
2773 folio_zero_segments(folio, 0, from,
2774 from + copied, folio_size(folio));
2775 }
2776 folio_mark_uptodate(folio);
2777 }
2778 folio_mark_dirty(folio);
2779 folio_unlock(folio);
2780 folio_put(folio);
2781
2782 return copied;
2783}
2784
2785static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2786{
2787 struct file *file = iocb->ki_filp;
2788 struct inode *inode = file_inode(file);
2789 struct address_space *mapping = inode->i_mapping;
2790 pgoff_t index;
2791 unsigned long offset;
2792 int error = 0;
2793 ssize_t retval = 0;
2794 loff_t *ppos = &iocb->ki_pos;
2795
2796 index = *ppos >> PAGE_SHIFT;
2797 offset = *ppos & ~PAGE_MASK;
2798
2799 for (;;) {
2800 struct folio *folio = NULL;
2801 struct page *page = NULL;
2802 pgoff_t end_index;
2803 unsigned long nr, ret;
2804 loff_t i_size = i_size_read(inode);
2805
2806 end_index = i_size >> PAGE_SHIFT;
2807 if (index > end_index)
2808 break;
2809 if (index == end_index) {
2810 nr = i_size & ~PAGE_MASK;
2811 if (nr <= offset)
2812 break;
2813 }
2814
2815 error = shmem_get_folio(inode, index, &folio, SGP_READ);
2816 if (error) {
2817 if (error == -EINVAL)
2818 error = 0;
2819 break;
2820 }
2821 if (folio) {
2822 folio_unlock(folio);
2823
2824 page = folio_file_page(folio, index);
2825 if (PageHWPoison(page)) {
2826 folio_put(folio);
2827 error = -EIO;
2828 break;
2829 }
2830 }
2831
2832 /*
2833 * We must evaluate after, since reads (unlike writes)
2834 * are called without i_rwsem protection against truncate
2835 */
2836 nr = PAGE_SIZE;
2837 i_size = i_size_read(inode);
2838 end_index = i_size >> PAGE_SHIFT;
2839 if (index == end_index) {
2840 nr = i_size & ~PAGE_MASK;
2841 if (nr <= offset) {
2842 if (folio)
2843 folio_put(folio);
2844 break;
2845 }
2846 }
2847 nr -= offset;
2848
2849 if (folio) {
2850 /*
2851 * If users can be writing to this page using arbitrary
2852 * virtual addresses, take care about potential aliasing
2853 * before reading the page on the kernel side.
2854 */
2855 if (mapping_writably_mapped(mapping))
2856 flush_dcache_page(page);
2857 /*
2858 * Mark the page accessed if we read the beginning.
2859 */
2860 if (!offset)
2861 folio_mark_accessed(folio);
2862 /*
2863 * Ok, we have the page, and it's up-to-date, so
2864 * now we can copy it to user space...
2865 */
2866 ret = copy_page_to_iter(page, offset, nr, to);
2867 folio_put(folio);
2868
2869 } else if (user_backed_iter(to)) {
2870 /*
2871 * Copy to user tends to be so well optimized, but
2872 * clear_user() not so much, that it is noticeably
2873 * faster to copy the zero page instead of clearing.
2874 */
2875 ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to);
2876 } else {
2877 /*
2878 * But submitting the same page twice in a row to
2879 * splice() - or others? - can result in confusion:
2880 * so don't attempt that optimization on pipes etc.
2881 */
2882 ret = iov_iter_zero(nr, to);
2883 }
2884
2885 retval += ret;
2886 offset += ret;
2887 index += offset >> PAGE_SHIFT;
2888 offset &= ~PAGE_MASK;
2889
2890 if (!iov_iter_count(to))
2891 break;
2892 if (ret < nr) {
2893 error = -EFAULT;
2894 break;
2895 }
2896 cond_resched();
2897 }
2898
2899 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2900 file_accessed(file);
2901 return retval ? retval : error;
2902}
2903
2904static ssize_t shmem_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
2905{
2906 struct file *file = iocb->ki_filp;
2907 struct inode *inode = file->f_mapping->host;
2908 ssize_t ret;
2909
2910 inode_lock(inode);
2911 ret = generic_write_checks(iocb, from);
2912 if (ret <= 0)
2913 goto unlock;
2914 ret = file_remove_privs(file);
2915 if (ret)
2916 goto unlock;
2917 ret = file_update_time(file);
2918 if (ret)
2919 goto unlock;
2920 ret = generic_perform_write(iocb, from);
2921unlock:
2922 inode_unlock(inode);
2923 return ret;
2924}
2925
2926static bool zero_pipe_buf_get(struct pipe_inode_info *pipe,
2927 struct pipe_buffer *buf)
2928{
2929 return true;
2930}
2931
2932static void zero_pipe_buf_release(struct pipe_inode_info *pipe,
2933 struct pipe_buffer *buf)
2934{
2935}
2936
2937static bool zero_pipe_buf_try_steal(struct pipe_inode_info *pipe,
2938 struct pipe_buffer *buf)
2939{
2940 return false;
2941}
2942
2943static const struct pipe_buf_operations zero_pipe_buf_ops = {
2944 .release = zero_pipe_buf_release,
2945 .try_steal = zero_pipe_buf_try_steal,
2946 .get = zero_pipe_buf_get,
2947};
2948
2949static size_t splice_zeropage_into_pipe(struct pipe_inode_info *pipe,
2950 loff_t fpos, size_t size)
2951{
2952 size_t offset = fpos & ~PAGE_MASK;
2953
2954 size = min_t(size_t, size, PAGE_SIZE - offset);
2955
2956 if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
2957 struct pipe_buffer *buf = pipe_head_buf(pipe);
2958
2959 *buf = (struct pipe_buffer) {
2960 .ops = &zero_pipe_buf_ops,
2961 .page = ZERO_PAGE(0),
2962 .offset = offset,
2963 .len = size,
2964 };
2965 pipe->head++;
2966 }
2967
2968 return size;
2969}
2970
2971static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
2972 struct pipe_inode_info *pipe,
2973 size_t len, unsigned int flags)
2974{
2975 struct inode *inode = file_inode(in);
2976 struct address_space *mapping = inode->i_mapping;
2977 struct folio *folio = NULL;
2978 size_t total_spliced = 0, used, npages, n, part;
2979 loff_t isize;
2980 int error = 0;
2981
2982 /* Work out how much data we can actually add into the pipe */
2983 used = pipe_occupancy(pipe->head, pipe->tail);
2984 npages = max_t(ssize_t, pipe->max_usage - used, 0);
2985 len = min_t(size_t, len, npages * PAGE_SIZE);
2986
2987 do {
2988 if (*ppos >= i_size_read(inode))
2989 break;
2990
2991 error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
2992 SGP_READ);
2993 if (error) {
2994 if (error == -EINVAL)
2995 error = 0;
2996 break;
2997 }
2998 if (folio) {
2999 folio_unlock(folio);
3000
3001 if (folio_test_hwpoison(folio) ||
3002 (folio_test_large(folio) &&
3003 folio_test_has_hwpoisoned(folio))) {
3004 error = -EIO;
3005 break;
3006 }
3007 }
3008
3009 /*
3010 * i_size must be checked after we know the pages are Uptodate.
3011 *
3012 * Checking i_size after the check allows us to calculate
3013 * the correct value for "nr", which means the zero-filled
3014 * part of the page is not copied back to userspace (unless
3015 * another truncate extends the file - this is desired though).
3016 */
3017 isize = i_size_read(inode);
3018 if (unlikely(*ppos >= isize))
3019 break;
3020 part = min_t(loff_t, isize - *ppos, len);
3021
3022 if (folio) {
3023 /*
3024 * If users can be writing to this page using arbitrary
3025 * virtual addresses, take care about potential aliasing
3026 * before reading the page on the kernel side.
3027 */
3028 if (mapping_writably_mapped(mapping))
3029 flush_dcache_folio(folio);
3030 folio_mark_accessed(folio);
3031 /*
3032 * Ok, we have the page, and it's up-to-date, so we can
3033 * now splice it into the pipe.
3034 */
3035 n = splice_folio_into_pipe(pipe, folio, *ppos, part);
3036 folio_put(folio);
3037 folio = NULL;
3038 } else {
3039 n = splice_zeropage_into_pipe(pipe, *ppos, part);
3040 }
3041
3042 if (!n)
3043 break;
3044 len -= n;
3045 total_spliced += n;
3046 *ppos += n;
3047 in->f_ra.prev_pos = *ppos;
3048 if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
3049 break;
3050
3051 cond_resched();
3052 } while (len);
3053
3054 if (folio)
3055 folio_put(folio);
3056
3057 file_accessed(in);
3058 return total_spliced ? total_spliced : error;
3059}
3060
3061static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
3062{
3063 struct address_space *mapping = file->f_mapping;
3064 struct inode *inode = mapping->host;
3065
3066 if (whence != SEEK_DATA && whence != SEEK_HOLE)
3067 return generic_file_llseek_size(file, offset, whence,
3068 MAX_LFS_FILESIZE, i_size_read(inode));
3069 if (offset < 0)
3070 return -ENXIO;
3071
3072 inode_lock(inode);
3073 /* We're holding i_rwsem so we can access i_size directly */
3074 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
3075 if (offset >= 0)
3076 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
3077 inode_unlock(inode);
3078 return offset;
3079}
3080
3081static long shmem_fallocate(struct file *file, int mode, loff_t offset,
3082 loff_t len)
3083{
3084 struct inode *inode = file_inode(file);
3085 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3086 struct shmem_inode_info *info = SHMEM_I(inode);
3087 struct shmem_falloc shmem_falloc;
3088 pgoff_t start, index, end, undo_fallocend;
3089 int error;
3090
3091 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
3092 return -EOPNOTSUPP;
3093
3094 inode_lock(inode);
3095
3096 if (mode & FALLOC_FL_PUNCH_HOLE) {
3097 struct address_space *mapping = file->f_mapping;
3098 loff_t unmap_start = round_up(offset, PAGE_SIZE);
3099 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
3100 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
3101
3102 /* protected by i_rwsem */
3103 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
3104 error = -EPERM;
3105 goto out;
3106 }
3107
3108 shmem_falloc.waitq = &shmem_falloc_waitq;
3109 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
3110 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
3111 spin_lock(&inode->i_lock);
3112 inode->i_private = &shmem_falloc;
3113 spin_unlock(&inode->i_lock);
3114
3115 if ((u64)unmap_end > (u64)unmap_start)
3116 unmap_mapping_range(mapping, unmap_start,
3117 1 + unmap_end - unmap_start, 0);
3118 shmem_truncate_range(inode, offset, offset + len - 1);
3119 /* No need to unmap again: hole-punching leaves COWed pages */
3120
3121 spin_lock(&inode->i_lock);
3122 inode->i_private = NULL;
3123 wake_up_all(&shmem_falloc_waitq);
3124 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
3125 spin_unlock(&inode->i_lock);
3126 error = 0;
3127 goto out;
3128 }
3129
3130 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
3131 error = inode_newsize_ok(inode, offset + len);
3132 if (error)
3133 goto out;
3134
3135 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
3136 error = -EPERM;
3137 goto out;
3138 }
3139
3140 start = offset >> PAGE_SHIFT;
3141 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
3142 /* Try to avoid a swapstorm if len is impossible to satisfy */
3143 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
3144 error = -ENOSPC;
3145 goto out;
3146 }
3147
3148 shmem_falloc.waitq = NULL;
3149 shmem_falloc.start = start;
3150 shmem_falloc.next = start;
3151 shmem_falloc.nr_falloced = 0;
3152 shmem_falloc.nr_unswapped = 0;
3153 spin_lock(&inode->i_lock);
3154 inode->i_private = &shmem_falloc;
3155 spin_unlock(&inode->i_lock);
3156
3157 /*
3158 * info->fallocend is only relevant when huge pages might be
3159 * involved: to prevent split_huge_page() freeing fallocated
3160 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
3161 */
3162 undo_fallocend = info->fallocend;
3163 if (info->fallocend < end)
3164 info->fallocend = end;
3165
3166 for (index = start; index < end; ) {
3167 struct folio *folio;
3168
3169 /*
3170 * Good, the fallocate(2) manpage permits EINTR: we may have
3171 * been interrupted because we are using up too much memory.
3172 */
3173 if (signal_pending(current))
3174 error = -EINTR;
3175 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
3176 error = -ENOMEM;
3177 else
3178 error = shmem_get_folio(inode, index, &folio,
3179 SGP_FALLOC);
3180 if (error) {
3181 info->fallocend = undo_fallocend;
3182 /* Remove the !uptodate folios we added */
3183 if (index > start) {
3184 shmem_undo_range(inode,
3185 (loff_t)start << PAGE_SHIFT,
3186 ((loff_t)index << PAGE_SHIFT) - 1, true);
3187 }
3188 goto undone;
3189 }
3190
3191 /*
3192 * Here is a more important optimization than it appears:
3193 * a second SGP_FALLOC on the same large folio will clear it,
3194 * making it uptodate and un-undoable if we fail later.
3195 */
3196 index = folio_next_index(folio);
3197 /* Beware 32-bit wraparound */
3198 if (!index)
3199 index--;
3200
3201 /*
3202 * Inform shmem_writepage() how far we have reached.
3203 * No need for lock or barrier: we have the page lock.
3204 */
3205 if (!folio_test_uptodate(folio))
3206 shmem_falloc.nr_falloced += index - shmem_falloc.next;
3207 shmem_falloc.next = index;
3208
3209 /*
3210 * If !uptodate, leave it that way so that freeable folios
3211 * can be recognized if we need to rollback on error later.
3212 * But mark it dirty so that memory pressure will swap rather
3213 * than free the folios we are allocating (and SGP_CACHE folios
3214 * might still be clean: we now need to mark those dirty too).
3215 */
3216 folio_mark_dirty(folio);
3217 folio_unlock(folio);
3218 folio_put(folio);
3219 cond_resched();
3220 }
3221
3222 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
3223 i_size_write(inode, offset + len);
3224undone:
3225 spin_lock(&inode->i_lock);
3226 inode->i_private = NULL;
3227 spin_unlock(&inode->i_lock);
3228out:
3229 if (!error)
3230 file_modified(file);
3231 inode_unlock(inode);
3232 return error;
3233}
3234
3235static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
3236{
3237 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
3238
3239 buf->f_type = TMPFS_MAGIC;
3240 buf->f_bsize = PAGE_SIZE;
3241 buf->f_namelen = NAME_MAX;
3242 if (sbinfo->max_blocks) {
3243 buf->f_blocks = sbinfo->max_blocks;
3244 buf->f_bavail =
3245 buf->f_bfree = sbinfo->max_blocks -
3246 percpu_counter_sum(&sbinfo->used_blocks);
3247 }
3248 if (sbinfo->max_inodes) {
3249 buf->f_files = sbinfo->max_inodes;
3250 buf->f_ffree = sbinfo->free_ispace / BOGO_INODE_SIZE;
3251 }
3252 /* else leave those fields 0 like simple_statfs */
3253
3254 buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
3255
3256 return 0;
3257}
3258
3259/*
3260 * File creation. Allocate an inode, and we're done..
3261 */
3262static int
3263shmem_mknod(struct mnt_idmap *idmap, struct inode *dir,
3264 struct dentry *dentry, umode_t mode, dev_t dev)
3265{
3266 struct inode *inode;
3267 int error;
3268
3269 inode = shmem_get_inode(idmap, dir->i_sb, dir, mode, dev, VM_NORESERVE);
3270 if (IS_ERR(inode))
3271 return PTR_ERR(inode);
3272
3273 error = simple_acl_create(dir, inode);
3274 if (error)
3275 goto out_iput;
3276 error = security_inode_init_security(inode, dir, &dentry->d_name,
3277 shmem_initxattrs, NULL);
3278 if (error && error != -EOPNOTSUPP)
3279 goto out_iput;
3280
3281 error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3282 if (error)
3283 goto out_iput;
3284
3285 dir->i_size += BOGO_DIRENT_SIZE;
3286 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
3287 inode_inc_iversion(dir);
3288 d_instantiate(dentry, inode);
3289 dget(dentry); /* Extra count - pin the dentry in core */
3290 return error;
3291
3292out_iput:
3293 iput(inode);
3294 return error;
3295}
3296
3297static int
3298shmem_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
3299 struct file *file, umode_t mode)
3300{
3301 struct inode *inode;
3302 int error;
3303
3304 inode = shmem_get_inode(idmap, dir->i_sb, dir, mode, 0, VM_NORESERVE);
3305 if (IS_ERR(inode)) {
3306 error = PTR_ERR(inode);
3307 goto err_out;
3308 }
3309 error = security_inode_init_security(inode, dir, NULL,
3310 shmem_initxattrs, NULL);
3311 if (error && error != -EOPNOTSUPP)
3312 goto out_iput;
3313 error = simple_acl_create(dir, inode);
3314 if (error)
3315 goto out_iput;
3316 d_tmpfile(file, inode);
3317
3318err_out:
3319 return finish_open_simple(file, error);
3320out_iput:
3321 iput(inode);
3322 return error;
3323}
3324
3325static int shmem_mkdir(struct mnt_idmap *idmap, struct inode *dir,
3326 struct dentry *dentry, umode_t mode)
3327{
3328 int error;
3329
3330 error = shmem_mknod(idmap, dir, dentry, mode | S_IFDIR, 0);
3331 if (error)
3332 return error;
3333 inc_nlink(dir);
3334 return 0;
3335}
3336
3337static int shmem_create(struct mnt_idmap *idmap, struct inode *dir,
3338 struct dentry *dentry, umode_t mode, bool excl)
3339{
3340 return shmem_mknod(idmap, dir, dentry, mode | S_IFREG, 0);
3341}
3342
3343/*
3344 * Link a file..
3345 */
3346static int shmem_link(struct dentry *old_dentry, struct inode *dir,
3347 struct dentry *dentry)
3348{
3349 struct inode *inode = d_inode(old_dentry);
3350 int ret = 0;
3351
3352 /*
3353 * No ordinary (disk based) filesystem counts links as inodes;
3354 * but each new link needs a new dentry, pinning lowmem, and
3355 * tmpfs dentries cannot be pruned until they are unlinked.
3356 * But if an O_TMPFILE file is linked into the tmpfs, the
3357 * first link must skip that, to get the accounting right.
3358 */
3359 if (inode->i_nlink) {
3360 ret = shmem_reserve_inode(inode->i_sb, NULL);
3361 if (ret)
3362 goto out;
3363 }
3364
3365 ret = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3366 if (ret) {
3367 if (inode->i_nlink)
3368 shmem_free_inode(inode->i_sb, 0);
3369 goto out;
3370 }
3371
3372 dir->i_size += BOGO_DIRENT_SIZE;
3373 inode_set_mtime_to_ts(dir,
3374 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
3375 inode_inc_iversion(dir);
3376 inc_nlink(inode);
3377 ihold(inode); /* New dentry reference */
3378 dget(dentry); /* Extra pinning count for the created dentry */
3379 d_instantiate(dentry, inode);
3380out:
3381 return ret;
3382}
3383
3384static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3385{
3386 struct inode *inode = d_inode(dentry);
3387
3388 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3389 shmem_free_inode(inode->i_sb, 0);
3390
3391 simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
3392
3393 dir->i_size -= BOGO_DIRENT_SIZE;
3394 inode_set_mtime_to_ts(dir,
3395 inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
3396 inode_inc_iversion(dir);
3397 drop_nlink(inode);
3398 dput(dentry); /* Undo the count from "create" - does all the work */
3399 return 0;
3400}
3401
3402static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3403{
3404 if (!simple_offset_empty(dentry))
3405 return -ENOTEMPTY;
3406
3407 drop_nlink(d_inode(dentry));
3408 drop_nlink(dir);
3409 return shmem_unlink(dir, dentry);
3410}
3411
3412static int shmem_whiteout(struct mnt_idmap *idmap,
3413 struct inode *old_dir, struct dentry *old_dentry)
3414{
3415 struct dentry *whiteout;
3416 int error;
3417
3418 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3419 if (!whiteout)
3420 return -ENOMEM;
3421
3422 error = shmem_mknod(idmap, old_dir, whiteout,
3423 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3424 dput(whiteout);
3425 if (error)
3426 return error;
3427
3428 /*
3429 * Cheat and hash the whiteout while the old dentry is still in
3430 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3431 *
3432 * d_lookup() will consistently find one of them at this point,
3433 * not sure which one, but that isn't even important.
3434 */
3435 d_rehash(whiteout);
3436 return 0;
3437}
3438
3439/*
3440 * The VFS layer already does all the dentry stuff for rename,
3441 * we just have to decrement the usage count for the target if
3442 * it exists so that the VFS layer correctly free's it when it
3443 * gets overwritten.
3444 */
3445static int shmem_rename2(struct mnt_idmap *idmap,
3446 struct inode *old_dir, struct dentry *old_dentry,
3447 struct inode *new_dir, struct dentry *new_dentry,
3448 unsigned int flags)
3449{
3450 struct inode *inode = d_inode(old_dentry);
3451 int they_are_dirs = S_ISDIR(inode->i_mode);
3452 int error;
3453
3454 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3455 return -EINVAL;
3456
3457 if (flags & RENAME_EXCHANGE)
3458 return simple_offset_rename_exchange(old_dir, old_dentry,
3459 new_dir, new_dentry);
3460
3461 if (!simple_offset_empty(new_dentry))
3462 return -ENOTEMPTY;
3463
3464 if (flags & RENAME_WHITEOUT) {
3465 error = shmem_whiteout(idmap, old_dir, old_dentry);
3466 if (error)
3467 return error;
3468 }
3469
3470 error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
3471 if (error)
3472 return error;
3473
3474 if (d_really_is_positive(new_dentry)) {
3475 (void) shmem_unlink(new_dir, new_dentry);
3476 if (they_are_dirs) {
3477 drop_nlink(d_inode(new_dentry));
3478 drop_nlink(old_dir);
3479 }
3480 } else if (they_are_dirs) {
3481 drop_nlink(old_dir);
3482 inc_nlink(new_dir);
3483 }
3484
3485 old_dir->i_size -= BOGO_DIRENT_SIZE;
3486 new_dir->i_size += BOGO_DIRENT_SIZE;
3487 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
3488 inode_inc_iversion(old_dir);
3489 inode_inc_iversion(new_dir);
3490 return 0;
3491}
3492
3493static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
3494 struct dentry *dentry, const char *symname)
3495{
3496 int error;
3497 int len;
3498 struct inode *inode;
3499 struct folio *folio;
3500
3501 len = strlen(symname) + 1;
3502 if (len > PAGE_SIZE)
3503 return -ENAMETOOLONG;
3504
3505 inode = shmem_get_inode(idmap, dir->i_sb, dir, S_IFLNK | 0777, 0,
3506 VM_NORESERVE);
3507 if (IS_ERR(inode))
3508 return PTR_ERR(inode);
3509
3510 error = security_inode_init_security(inode, dir, &dentry->d_name,
3511 shmem_initxattrs, NULL);
3512 if (error && error != -EOPNOTSUPP)
3513 goto out_iput;
3514
3515 error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3516 if (error)
3517 goto out_iput;
3518
3519 inode->i_size = len-1;
3520 if (len <= SHORT_SYMLINK_LEN) {
3521 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3522 if (!inode->i_link) {
3523 error = -ENOMEM;
3524 goto out_remove_offset;
3525 }
3526 inode->i_op = &shmem_short_symlink_operations;
3527 } else {
3528 inode_nohighmem(inode);
3529 inode->i_mapping->a_ops = &shmem_aops;
3530 error = shmem_get_folio(inode, 0, &folio, SGP_WRITE);
3531 if (error)
3532 goto out_remove_offset;
3533 inode->i_op = &shmem_symlink_inode_operations;
3534 memcpy(folio_address(folio), symname, len);
3535 folio_mark_uptodate(folio);
3536 folio_mark_dirty(folio);
3537 folio_unlock(folio);
3538 folio_put(folio);
3539 }
3540 dir->i_size += BOGO_DIRENT_SIZE;
3541 inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
3542 inode_inc_iversion(dir);
3543 d_instantiate(dentry, inode);
3544 dget(dentry);
3545 return 0;
3546
3547out_remove_offset:
3548 simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
3549out_iput:
3550 iput(inode);
3551 return error;
3552}
3553
3554static void shmem_put_link(void *arg)
3555{
3556 folio_mark_accessed(arg);
3557 folio_put(arg);
3558}
3559
3560static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
3561 struct delayed_call *done)
3562{
3563 struct folio *folio = NULL;
3564 int error;
3565
3566 if (!dentry) {
3567 folio = filemap_get_folio(inode->i_mapping, 0);
3568 if (IS_ERR(folio))
3569 return ERR_PTR(-ECHILD);
3570 if (PageHWPoison(folio_page(folio, 0)) ||
3571 !folio_test_uptodate(folio)) {
3572 folio_put(folio);
3573 return ERR_PTR(-ECHILD);
3574 }
3575 } else {
3576 error = shmem_get_folio(inode, 0, &folio, SGP_READ);
3577 if (error)
3578 return ERR_PTR(error);
3579 if (!folio)
3580 return ERR_PTR(-ECHILD);
3581 if (PageHWPoison(folio_page(folio, 0))) {
3582 folio_unlock(folio);
3583 folio_put(folio);
3584 return ERR_PTR(-ECHILD);
3585 }
3586 folio_unlock(folio);
3587 }
3588 set_delayed_call(done, shmem_put_link, folio);
3589 return folio_address(folio);
3590}
3591
3592#ifdef CONFIG_TMPFS_XATTR
3593
3594static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
3595{
3596 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3597
3598 fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
3599
3600 return 0;
3601}
3602
3603static int shmem_fileattr_set(struct mnt_idmap *idmap,
3604 struct dentry *dentry, struct fileattr *fa)
3605{
3606 struct inode *inode = d_inode(dentry);
3607 struct shmem_inode_info *info = SHMEM_I(inode);
3608
3609 if (fileattr_has_fsx(fa))
3610 return -EOPNOTSUPP;
3611 if (fa->flags & ~SHMEM_FL_USER_MODIFIABLE)
3612 return -EOPNOTSUPP;
3613
3614 info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
3615 (fa->flags & SHMEM_FL_USER_MODIFIABLE);
3616
3617 shmem_set_inode_flags(inode, info->fsflags);
3618 inode_set_ctime_current(inode);
3619 inode_inc_iversion(inode);
3620 return 0;
3621}
3622
3623/*
3624 * Superblocks without xattr inode operations may get some security.* xattr
3625 * support from the LSM "for free". As soon as we have any other xattrs
3626 * like ACLs, we also need to implement the security.* handlers at
3627 * filesystem level, though.
3628 */
3629
3630/*
3631 * Callback for security_inode_init_security() for acquiring xattrs.
3632 */
3633static int shmem_initxattrs(struct inode *inode,
3634 const struct xattr *xattr_array, void *fs_info)
3635{
3636 struct shmem_inode_info *info = SHMEM_I(inode);
3637 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3638 const struct xattr *xattr;
3639 struct simple_xattr *new_xattr;
3640 size_t ispace = 0;
3641 size_t len;
3642
3643 if (sbinfo->max_inodes) {
3644 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3645 ispace += simple_xattr_space(xattr->name,
3646 xattr->value_len + XATTR_SECURITY_PREFIX_LEN);
3647 }
3648 if (ispace) {
3649 raw_spin_lock(&sbinfo->stat_lock);
3650 if (sbinfo->free_ispace < ispace)
3651 ispace = 0;
3652 else
3653 sbinfo->free_ispace -= ispace;
3654 raw_spin_unlock(&sbinfo->stat_lock);
3655 if (!ispace)
3656 return -ENOSPC;
3657 }
3658 }
3659
3660 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3661 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3662 if (!new_xattr)
3663 break;
3664
3665 len = strlen(xattr->name) + 1;
3666 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3667 GFP_KERNEL_ACCOUNT);
3668 if (!new_xattr->name) {
3669 kvfree(new_xattr);
3670 break;
3671 }
3672
3673 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3674 XATTR_SECURITY_PREFIX_LEN);
3675 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3676 xattr->name, len);
3677
3678 simple_xattr_add(&info->xattrs, new_xattr);
3679 }
3680
3681 if (xattr->name != NULL) {
3682 if (ispace) {
3683 raw_spin_lock(&sbinfo->stat_lock);
3684 sbinfo->free_ispace += ispace;
3685 raw_spin_unlock(&sbinfo->stat_lock);
3686 }
3687 simple_xattrs_free(&info->xattrs, NULL);
3688 return -ENOMEM;
3689 }
3690
3691 return 0;
3692}
3693
3694static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3695 struct dentry *unused, struct inode *inode,
3696 const char *name, void *buffer, size_t size)
3697{
3698 struct shmem_inode_info *info = SHMEM_I(inode);
3699
3700 name = xattr_full_name(handler, name);
3701 return simple_xattr_get(&info->xattrs, name, buffer, size);
3702}
3703
3704static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3705 struct mnt_idmap *idmap,
3706 struct dentry *unused, struct inode *inode,
3707 const char *name, const void *value,
3708 size_t size, int flags)
3709{
3710 struct shmem_inode_info *info = SHMEM_I(inode);
3711 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3712 struct simple_xattr *old_xattr;
3713 size_t ispace = 0;
3714
3715 name = xattr_full_name(handler, name);
3716 if (value && sbinfo->max_inodes) {
3717 ispace = simple_xattr_space(name, size);
3718 raw_spin_lock(&sbinfo->stat_lock);
3719 if (sbinfo->free_ispace < ispace)
3720 ispace = 0;
3721 else
3722 sbinfo->free_ispace -= ispace;
3723 raw_spin_unlock(&sbinfo->stat_lock);
3724 if (!ispace)
3725 return -ENOSPC;
3726 }
3727
3728 old_xattr = simple_xattr_set(&info->xattrs, name, value, size, flags);
3729 if (!IS_ERR(old_xattr)) {
3730 ispace = 0;
3731 if (old_xattr && sbinfo->max_inodes)
3732 ispace = simple_xattr_space(old_xattr->name,
3733 old_xattr->size);
3734 simple_xattr_free(old_xattr);
3735 old_xattr = NULL;
3736 inode_set_ctime_current(inode);
3737 inode_inc_iversion(inode);
3738 }
3739 if (ispace) {
3740 raw_spin_lock(&sbinfo->stat_lock);
3741 sbinfo->free_ispace += ispace;
3742 raw_spin_unlock(&sbinfo->stat_lock);
3743 }
3744 return PTR_ERR(old_xattr);
3745}
3746
3747static const struct xattr_handler shmem_security_xattr_handler = {
3748 .prefix = XATTR_SECURITY_PREFIX,
3749 .get = shmem_xattr_handler_get,
3750 .set = shmem_xattr_handler_set,
3751};
3752
3753static const struct xattr_handler shmem_trusted_xattr_handler = {
3754 .prefix = XATTR_TRUSTED_PREFIX,
3755 .get = shmem_xattr_handler_get,
3756 .set = shmem_xattr_handler_set,
3757};
3758
3759static const struct xattr_handler shmem_user_xattr_handler = {
3760 .prefix = XATTR_USER_PREFIX,
3761 .get = shmem_xattr_handler_get,
3762 .set = shmem_xattr_handler_set,
3763};
3764
3765static const struct xattr_handler * const shmem_xattr_handlers[] = {
3766 &shmem_security_xattr_handler,
3767 &shmem_trusted_xattr_handler,
3768 &shmem_user_xattr_handler,
3769 NULL
3770};
3771
3772static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3773{
3774 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3775 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3776}
3777#endif /* CONFIG_TMPFS_XATTR */
3778
3779static const struct inode_operations shmem_short_symlink_operations = {
3780 .getattr = shmem_getattr,
3781 .setattr = shmem_setattr,
3782 .get_link = simple_get_link,
3783#ifdef CONFIG_TMPFS_XATTR
3784 .listxattr = shmem_listxattr,
3785#endif
3786};
3787
3788static const struct inode_operations shmem_symlink_inode_operations = {
3789 .getattr = shmem_getattr,
3790 .setattr = shmem_setattr,
3791 .get_link = shmem_get_link,
3792#ifdef CONFIG_TMPFS_XATTR
3793 .listxattr = shmem_listxattr,
3794#endif
3795};
3796
3797static struct dentry *shmem_get_parent(struct dentry *child)
3798{
3799 return ERR_PTR(-ESTALE);
3800}
3801
3802static int shmem_match(struct inode *ino, void *vfh)
3803{
3804 __u32 *fh = vfh;
3805 __u64 inum = fh[2];
3806 inum = (inum << 32) | fh[1];
3807 return ino->i_ino == inum && fh[0] == ino->i_generation;
3808}
3809
3810/* Find any alias of inode, but prefer a hashed alias */
3811static struct dentry *shmem_find_alias(struct inode *inode)
3812{
3813 struct dentry *alias = d_find_alias(inode);
3814
3815 return alias ?: d_find_any_alias(inode);
3816}
3817
3818static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3819 struct fid *fid, int fh_len, int fh_type)
3820{
3821 struct inode *inode;
3822 struct dentry *dentry = NULL;
3823 u64 inum;
3824
3825 if (fh_len < 3)
3826 return NULL;
3827
3828 inum = fid->raw[2];
3829 inum = (inum << 32) | fid->raw[1];
3830
3831 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3832 shmem_match, fid->raw);
3833 if (inode) {
3834 dentry = shmem_find_alias(inode);
3835 iput(inode);
3836 }
3837
3838 return dentry;
3839}
3840
3841static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3842 struct inode *parent)
3843{
3844 if (*len < 3) {
3845 *len = 3;
3846 return FILEID_INVALID;
3847 }
3848
3849 if (inode_unhashed(inode)) {
3850 /* Unfortunately insert_inode_hash is not idempotent,
3851 * so as we hash inodes here rather than at creation
3852 * time, we need a lock to ensure we only try
3853 * to do it once
3854 */
3855 static DEFINE_SPINLOCK(lock);
3856 spin_lock(&lock);
3857 if (inode_unhashed(inode))
3858 __insert_inode_hash(inode,
3859 inode->i_ino + inode->i_generation);
3860 spin_unlock(&lock);
3861 }
3862
3863 fh[0] = inode->i_generation;
3864 fh[1] = inode->i_ino;
3865 fh[2] = ((__u64)inode->i_ino) >> 32;
3866
3867 *len = 3;
3868 return 1;
3869}
3870
3871static const struct export_operations shmem_export_ops = {
3872 .get_parent = shmem_get_parent,
3873 .encode_fh = shmem_encode_fh,
3874 .fh_to_dentry = shmem_fh_to_dentry,
3875};
3876
3877enum shmem_param {
3878 Opt_gid,
3879 Opt_huge,
3880 Opt_mode,
3881 Opt_mpol,
3882 Opt_nr_blocks,
3883 Opt_nr_inodes,
3884 Opt_size,
3885 Opt_uid,
3886 Opt_inode32,
3887 Opt_inode64,
3888 Opt_noswap,
3889 Opt_quota,
3890 Opt_usrquota,
3891 Opt_grpquota,
3892 Opt_usrquota_block_hardlimit,
3893 Opt_usrquota_inode_hardlimit,
3894 Opt_grpquota_block_hardlimit,
3895 Opt_grpquota_inode_hardlimit,
3896};
3897
3898static const struct constant_table shmem_param_enums_huge[] = {
3899 {"never", SHMEM_HUGE_NEVER },
3900 {"always", SHMEM_HUGE_ALWAYS },
3901 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3902 {"advise", SHMEM_HUGE_ADVISE },
3903 {}
3904};
3905
3906const struct fs_parameter_spec shmem_fs_parameters[] = {
3907 fsparam_u32 ("gid", Opt_gid),
3908 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3909 fsparam_u32oct("mode", Opt_mode),
3910 fsparam_string("mpol", Opt_mpol),
3911 fsparam_string("nr_blocks", Opt_nr_blocks),
3912 fsparam_string("nr_inodes", Opt_nr_inodes),
3913 fsparam_string("size", Opt_size),
3914 fsparam_u32 ("uid", Opt_uid),
3915 fsparam_flag ("inode32", Opt_inode32),
3916 fsparam_flag ("inode64", Opt_inode64),
3917 fsparam_flag ("noswap", Opt_noswap),
3918#ifdef CONFIG_TMPFS_QUOTA
3919 fsparam_flag ("quota", Opt_quota),
3920 fsparam_flag ("usrquota", Opt_usrquota),
3921 fsparam_flag ("grpquota", Opt_grpquota),
3922 fsparam_string("usrquota_block_hardlimit", Opt_usrquota_block_hardlimit),
3923 fsparam_string("usrquota_inode_hardlimit", Opt_usrquota_inode_hardlimit),
3924 fsparam_string("grpquota_block_hardlimit", Opt_grpquota_block_hardlimit),
3925 fsparam_string("grpquota_inode_hardlimit", Opt_grpquota_inode_hardlimit),
3926#endif
3927 {}
3928};
3929
3930static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3931{
3932 struct shmem_options *ctx = fc->fs_private;
3933 struct fs_parse_result result;
3934 unsigned long long size;
3935 char *rest;
3936 int opt;
3937 kuid_t kuid;
3938 kgid_t kgid;
3939
3940 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3941 if (opt < 0)
3942 return opt;
3943
3944 switch (opt) {
3945 case Opt_size:
3946 size = memparse(param->string, &rest);
3947 if (*rest == '%') {
3948 size <<= PAGE_SHIFT;
3949 size *= totalram_pages();
3950 do_div(size, 100);
3951 rest++;
3952 }
3953 if (*rest)
3954 goto bad_value;
3955 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3956 ctx->seen |= SHMEM_SEEN_BLOCKS;
3957 break;
3958 case Opt_nr_blocks:
3959 ctx->blocks = memparse(param->string, &rest);
3960 if (*rest || ctx->blocks > LONG_MAX)
3961 goto bad_value;
3962 ctx->seen |= SHMEM_SEEN_BLOCKS;
3963 break;
3964 case Opt_nr_inodes:
3965 ctx->inodes = memparse(param->string, &rest);
3966 if (*rest || ctx->inodes > ULONG_MAX / BOGO_INODE_SIZE)
3967 goto bad_value;
3968 ctx->seen |= SHMEM_SEEN_INODES;
3969 break;
3970 case Opt_mode:
3971 ctx->mode = result.uint_32 & 07777;
3972 break;
3973 case Opt_uid:
3974 kuid = make_kuid(current_user_ns(), result.uint_32);
3975 if (!uid_valid(kuid))
3976 goto bad_value;
3977
3978 /*
3979 * The requested uid must be representable in the
3980 * filesystem's idmapping.
3981 */
3982 if (!kuid_has_mapping(fc->user_ns, kuid))
3983 goto bad_value;
3984
3985 ctx->uid = kuid;
3986 break;
3987 case Opt_gid:
3988 kgid = make_kgid(current_user_ns(), result.uint_32);
3989 if (!gid_valid(kgid))
3990 goto bad_value;
3991
3992 /*
3993 * The requested gid must be representable in the
3994 * filesystem's idmapping.
3995 */
3996 if (!kgid_has_mapping(fc->user_ns, kgid))
3997 goto bad_value;
3998
3999 ctx->gid = kgid;
4000 break;
4001 case Opt_huge:
4002 ctx->huge = result.uint_32;
4003 if (ctx->huge != SHMEM_HUGE_NEVER &&
4004 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
4005 has_transparent_hugepage()))
4006 goto unsupported_parameter;
4007 ctx->seen |= SHMEM_SEEN_HUGE;
4008 break;
4009 case Opt_mpol:
4010 if (IS_ENABLED(CONFIG_NUMA)) {
4011 mpol_put(ctx->mpol);
4012 ctx->mpol = NULL;
4013 if (mpol_parse_str(param->string, &ctx->mpol))
4014 goto bad_value;
4015 break;
4016 }
4017 goto unsupported_parameter;
4018 case Opt_inode32:
4019 ctx->full_inums = false;
4020 ctx->seen |= SHMEM_SEEN_INUMS;
4021 break;
4022 case Opt_inode64:
4023 if (sizeof(ino_t) < 8) {
4024 return invalfc(fc,
4025 "Cannot use inode64 with <64bit inums in kernel\n");
4026 }
4027 ctx->full_inums = true;
4028 ctx->seen |= SHMEM_SEEN_INUMS;
4029 break;
4030 case Opt_noswap:
4031 if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN)) {
4032 return invalfc(fc,
4033 "Turning off swap in unprivileged tmpfs mounts unsupported");
4034 }
4035 ctx->noswap = true;
4036 ctx->seen |= SHMEM_SEEN_NOSWAP;
4037 break;
4038 case Opt_quota:
4039 if (fc->user_ns != &init_user_ns)
4040 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4041 ctx->seen |= SHMEM_SEEN_QUOTA;
4042 ctx->quota_types |= (QTYPE_MASK_USR | QTYPE_MASK_GRP);
4043 break;
4044 case Opt_usrquota:
4045 if (fc->user_ns != &init_user_ns)
4046 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4047 ctx->seen |= SHMEM_SEEN_QUOTA;
4048 ctx->quota_types |= QTYPE_MASK_USR;
4049 break;
4050 case Opt_grpquota:
4051 if (fc->user_ns != &init_user_ns)
4052 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4053 ctx->seen |= SHMEM_SEEN_QUOTA;
4054 ctx->quota_types |= QTYPE_MASK_GRP;
4055 break;
4056 case Opt_usrquota_block_hardlimit:
4057 size = memparse(param->string, &rest);
4058 if (*rest || !size)
4059 goto bad_value;
4060 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4061 return invalfc(fc,
4062 "User quota block hardlimit too large.");
4063 ctx->qlimits.usrquota_bhardlimit = size;
4064 break;
4065 case Opt_grpquota_block_hardlimit:
4066 size = memparse(param->string, &rest);
4067 if (*rest || !size)
4068 goto bad_value;
4069 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4070 return invalfc(fc,
4071 "Group quota block hardlimit too large.");
4072 ctx->qlimits.grpquota_bhardlimit = size;
4073 break;
4074 case Opt_usrquota_inode_hardlimit:
4075 size = memparse(param->string, &rest);
4076 if (*rest || !size)
4077 goto bad_value;
4078 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4079 return invalfc(fc,
4080 "User quota inode hardlimit too large.");
4081 ctx->qlimits.usrquota_ihardlimit = size;
4082 break;
4083 case Opt_grpquota_inode_hardlimit:
4084 size = memparse(param->string, &rest);
4085 if (*rest || !size)
4086 goto bad_value;
4087 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4088 return invalfc(fc,
4089 "Group quota inode hardlimit too large.");
4090 ctx->qlimits.grpquota_ihardlimit = size;
4091 break;
4092 }
4093 return 0;
4094
4095unsupported_parameter:
4096 return invalfc(fc, "Unsupported parameter '%s'", param->key);
4097bad_value:
4098 return invalfc(fc, "Bad value for '%s'", param->key);
4099}
4100
4101static int shmem_parse_options(struct fs_context *fc, void *data)
4102{
4103 char *options = data;
4104
4105 if (options) {
4106 int err = security_sb_eat_lsm_opts(options, &fc->security);
4107 if (err)
4108 return err;
4109 }
4110
4111 while (options != NULL) {
4112 char *this_char = options;
4113 for (;;) {
4114 /*
4115 * NUL-terminate this option: unfortunately,
4116 * mount options form a comma-separated list,
4117 * but mpol's nodelist may also contain commas.
4118 */
4119 options = strchr(options, ',');
4120 if (options == NULL)
4121 break;
4122 options++;
4123 if (!isdigit(*options)) {
4124 options[-1] = '\0';
4125 break;
4126 }
4127 }
4128 if (*this_char) {
4129 char *value = strchr(this_char, '=');
4130 size_t len = 0;
4131 int err;
4132
4133 if (value) {
4134 *value++ = '\0';
4135 len = strlen(value);
4136 }
4137 err = vfs_parse_fs_string(fc, this_char, value, len);
4138 if (err < 0)
4139 return err;
4140 }
4141 }
4142 return 0;
4143}
4144
4145/*
4146 * Reconfigure a shmem filesystem.
4147 */
4148static int shmem_reconfigure(struct fs_context *fc)
4149{
4150 struct shmem_options *ctx = fc->fs_private;
4151 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
4152 unsigned long used_isp;
4153 struct mempolicy *mpol = NULL;
4154 const char *err;
4155
4156 raw_spin_lock(&sbinfo->stat_lock);
4157 used_isp = sbinfo->max_inodes * BOGO_INODE_SIZE - sbinfo->free_ispace;
4158
4159 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
4160 if (!sbinfo->max_blocks) {
4161 err = "Cannot retroactively limit size";
4162 goto out;
4163 }
4164 if (percpu_counter_compare(&sbinfo->used_blocks,
4165 ctx->blocks) > 0) {
4166 err = "Too small a size for current use";
4167 goto out;
4168 }
4169 }
4170 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
4171 if (!sbinfo->max_inodes) {
4172 err = "Cannot retroactively limit inodes";
4173 goto out;
4174 }
4175 if (ctx->inodes * BOGO_INODE_SIZE < used_isp) {
4176 err = "Too few inodes for current use";
4177 goto out;
4178 }
4179 }
4180
4181 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
4182 sbinfo->next_ino > UINT_MAX) {
4183 err = "Current inum too high to switch to 32-bit inums";
4184 goto out;
4185 }
4186 if ((ctx->seen & SHMEM_SEEN_NOSWAP) && ctx->noswap && !sbinfo->noswap) {
4187 err = "Cannot disable swap on remount";
4188 goto out;
4189 }
4190 if (!(ctx->seen & SHMEM_SEEN_NOSWAP) && !ctx->noswap && sbinfo->noswap) {
4191 err = "Cannot enable swap on remount if it was disabled on first mount";
4192 goto out;
4193 }
4194
4195 if (ctx->seen & SHMEM_SEEN_QUOTA &&
4196 !sb_any_quota_loaded(fc->root->d_sb)) {
4197 err = "Cannot enable quota on remount";
4198 goto out;
4199 }
4200
4201#ifdef CONFIG_TMPFS_QUOTA
4202#define CHANGED_LIMIT(name) \
4203 (ctx->qlimits.name## hardlimit && \
4204 (ctx->qlimits.name## hardlimit != sbinfo->qlimits.name## hardlimit))
4205
4206 if (CHANGED_LIMIT(usrquota_b) || CHANGED_LIMIT(usrquota_i) ||
4207 CHANGED_LIMIT(grpquota_b) || CHANGED_LIMIT(grpquota_i)) {
4208 err = "Cannot change global quota limit on remount";
4209 goto out;
4210 }
4211#endif /* CONFIG_TMPFS_QUOTA */
4212
4213 if (ctx->seen & SHMEM_SEEN_HUGE)
4214 sbinfo->huge = ctx->huge;
4215 if (ctx->seen & SHMEM_SEEN_INUMS)
4216 sbinfo->full_inums = ctx->full_inums;
4217 if (ctx->seen & SHMEM_SEEN_BLOCKS)
4218 sbinfo->max_blocks = ctx->blocks;
4219 if (ctx->seen & SHMEM_SEEN_INODES) {
4220 sbinfo->max_inodes = ctx->inodes;
4221 sbinfo->free_ispace = ctx->inodes * BOGO_INODE_SIZE - used_isp;
4222 }
4223
4224 /*
4225 * Preserve previous mempolicy unless mpol remount option was specified.
4226 */
4227 if (ctx->mpol) {
4228 mpol = sbinfo->mpol;
4229 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
4230 ctx->mpol = NULL;
4231 }
4232
4233 if (ctx->noswap)
4234 sbinfo->noswap = true;
4235
4236 raw_spin_unlock(&sbinfo->stat_lock);
4237 mpol_put(mpol);
4238 return 0;
4239out:
4240 raw_spin_unlock(&sbinfo->stat_lock);
4241 return invalfc(fc, "%s", err);
4242}
4243
4244static int shmem_show_options(struct seq_file *seq, struct dentry *root)
4245{
4246 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
4247 struct mempolicy *mpol;
4248
4249 if (sbinfo->max_blocks != shmem_default_max_blocks())
4250 seq_printf(seq, ",size=%luk", K(sbinfo->max_blocks));
4251 if (sbinfo->max_inodes != shmem_default_max_inodes())
4252 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
4253 if (sbinfo->mode != (0777 | S_ISVTX))
4254 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
4255 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
4256 seq_printf(seq, ",uid=%u",
4257 from_kuid_munged(&init_user_ns, sbinfo->uid));
4258 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
4259 seq_printf(seq, ",gid=%u",
4260 from_kgid_munged(&init_user_ns, sbinfo->gid));
4261
4262 /*
4263 * Showing inode{64,32} might be useful even if it's the system default,
4264 * since then people don't have to resort to checking both here and
4265 * /proc/config.gz to confirm 64-bit inums were successfully applied
4266 * (which may not even exist if IKCONFIG_PROC isn't enabled).
4267 *
4268 * We hide it when inode64 isn't the default and we are using 32-bit
4269 * inodes, since that probably just means the feature isn't even under
4270 * consideration.
4271 *
4272 * As such:
4273 *
4274 * +-----------------+-----------------+
4275 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
4276 * +------------------+-----------------+-----------------+
4277 * | full_inums=true | show | show |
4278 * | full_inums=false | show | hide |
4279 * +------------------+-----------------+-----------------+
4280 *
4281 */
4282 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
4283 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
4284#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4285 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
4286 if (sbinfo->huge)
4287 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
4288#endif
4289 mpol = shmem_get_sbmpol(sbinfo);
4290 shmem_show_mpol(seq, mpol);
4291 mpol_put(mpol);
4292 if (sbinfo->noswap)
4293 seq_printf(seq, ",noswap");
4294#ifdef CONFIG_TMPFS_QUOTA
4295 if (sb_has_quota_active(root->d_sb, USRQUOTA))
4296 seq_printf(seq, ",usrquota");
4297 if (sb_has_quota_active(root->d_sb, GRPQUOTA))
4298 seq_printf(seq, ",grpquota");
4299 if (sbinfo->qlimits.usrquota_bhardlimit)
4300 seq_printf(seq, ",usrquota_block_hardlimit=%lld",
4301 sbinfo->qlimits.usrquota_bhardlimit);
4302 if (sbinfo->qlimits.grpquota_bhardlimit)
4303 seq_printf(seq, ",grpquota_block_hardlimit=%lld",
4304 sbinfo->qlimits.grpquota_bhardlimit);
4305 if (sbinfo->qlimits.usrquota_ihardlimit)
4306 seq_printf(seq, ",usrquota_inode_hardlimit=%lld",
4307 sbinfo->qlimits.usrquota_ihardlimit);
4308 if (sbinfo->qlimits.grpquota_ihardlimit)
4309 seq_printf(seq, ",grpquota_inode_hardlimit=%lld",
4310 sbinfo->qlimits.grpquota_ihardlimit);
4311#endif
4312 return 0;
4313}
4314
4315#endif /* CONFIG_TMPFS */
4316
4317static void shmem_put_super(struct super_block *sb)
4318{
4319 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
4320
4321#ifdef CONFIG_TMPFS_QUOTA
4322 shmem_disable_quotas(sb);
4323#endif
4324 free_percpu(sbinfo->ino_batch);
4325 percpu_counter_destroy(&sbinfo->used_blocks);
4326 mpol_put(sbinfo->mpol);
4327 kfree(sbinfo);
4328 sb->s_fs_info = NULL;
4329}
4330
4331static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
4332{
4333 struct shmem_options *ctx = fc->fs_private;
4334 struct inode *inode;
4335 struct shmem_sb_info *sbinfo;
4336 int error = -ENOMEM;
4337
4338 /* Round up to L1_CACHE_BYTES to resist false sharing */
4339 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
4340 L1_CACHE_BYTES), GFP_KERNEL);
4341 if (!sbinfo)
4342 return error;
4343
4344 sb->s_fs_info = sbinfo;
4345
4346#ifdef CONFIG_TMPFS
4347 /*
4348 * Per default we only allow half of the physical ram per
4349 * tmpfs instance, limiting inodes to one per page of lowmem;
4350 * but the internal instance is left unlimited.
4351 */
4352 if (!(sb->s_flags & SB_KERNMOUNT)) {
4353 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
4354 ctx->blocks = shmem_default_max_blocks();
4355 if (!(ctx->seen & SHMEM_SEEN_INODES))
4356 ctx->inodes = shmem_default_max_inodes();
4357 if (!(ctx->seen & SHMEM_SEEN_INUMS))
4358 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
4359 sbinfo->noswap = ctx->noswap;
4360 } else {
4361 sb->s_flags |= SB_NOUSER;
4362 }
4363 sb->s_export_op = &shmem_export_ops;
4364 sb->s_flags |= SB_NOSEC | SB_I_VERSION;
4365#else
4366 sb->s_flags |= SB_NOUSER;
4367#endif
4368 sbinfo->max_blocks = ctx->blocks;
4369 sbinfo->max_inodes = ctx->inodes;
4370 sbinfo->free_ispace = sbinfo->max_inodes * BOGO_INODE_SIZE;
4371 if (sb->s_flags & SB_KERNMOUNT) {
4372 sbinfo->ino_batch = alloc_percpu(ino_t);
4373 if (!sbinfo->ino_batch)
4374 goto failed;
4375 }
4376 sbinfo->uid = ctx->uid;
4377 sbinfo->gid = ctx->gid;
4378 sbinfo->full_inums = ctx->full_inums;
4379 sbinfo->mode = ctx->mode;
4380 sbinfo->huge = ctx->huge;
4381 sbinfo->mpol = ctx->mpol;
4382 ctx->mpol = NULL;
4383
4384 raw_spin_lock_init(&sbinfo->stat_lock);
4385 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
4386 goto failed;
4387 spin_lock_init(&sbinfo->shrinklist_lock);
4388 INIT_LIST_HEAD(&sbinfo->shrinklist);
4389
4390 sb->s_maxbytes = MAX_LFS_FILESIZE;
4391 sb->s_blocksize = PAGE_SIZE;
4392 sb->s_blocksize_bits = PAGE_SHIFT;
4393 sb->s_magic = TMPFS_MAGIC;
4394 sb->s_op = &shmem_ops;
4395 sb->s_time_gran = 1;
4396#ifdef CONFIG_TMPFS_XATTR
4397 sb->s_xattr = shmem_xattr_handlers;
4398#endif
4399#ifdef CONFIG_TMPFS_POSIX_ACL
4400 sb->s_flags |= SB_POSIXACL;
4401#endif
4402 uuid_t uuid;
4403 uuid_gen(&uuid);
4404 super_set_uuid(sb, uuid.b, sizeof(uuid));
4405
4406#ifdef CONFIG_TMPFS_QUOTA
4407 if (ctx->seen & SHMEM_SEEN_QUOTA) {
4408 sb->dq_op = &shmem_quota_operations;
4409 sb->s_qcop = &dquot_quotactl_sysfile_ops;
4410 sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
4411
4412 /* Copy the default limits from ctx into sbinfo */
4413 memcpy(&sbinfo->qlimits, &ctx->qlimits,
4414 sizeof(struct shmem_quota_limits));
4415
4416 if (shmem_enable_quotas(sb, ctx->quota_types))
4417 goto failed;
4418 }
4419#endif /* CONFIG_TMPFS_QUOTA */
4420
4421 inode = shmem_get_inode(&nop_mnt_idmap, sb, NULL,
4422 S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
4423 if (IS_ERR(inode)) {
4424 error = PTR_ERR(inode);
4425 goto failed;
4426 }
4427 inode->i_uid = sbinfo->uid;
4428 inode->i_gid = sbinfo->gid;
4429 sb->s_root = d_make_root(inode);
4430 if (!sb->s_root)
4431 goto failed;
4432 return 0;
4433
4434failed:
4435 shmem_put_super(sb);
4436 return error;
4437}
4438
4439static int shmem_get_tree(struct fs_context *fc)
4440{
4441 return get_tree_nodev(fc, shmem_fill_super);
4442}
4443
4444static void shmem_free_fc(struct fs_context *fc)
4445{
4446 struct shmem_options *ctx = fc->fs_private;
4447
4448 if (ctx) {
4449 mpol_put(ctx->mpol);
4450 kfree(ctx);
4451 }
4452}
4453
4454static const struct fs_context_operations shmem_fs_context_ops = {
4455 .free = shmem_free_fc,
4456 .get_tree = shmem_get_tree,
4457#ifdef CONFIG_TMPFS
4458 .parse_monolithic = shmem_parse_options,
4459 .parse_param = shmem_parse_one,
4460 .reconfigure = shmem_reconfigure,
4461#endif
4462};
4463
4464static struct kmem_cache *shmem_inode_cachep __ro_after_init;
4465
4466static struct inode *shmem_alloc_inode(struct super_block *sb)
4467{
4468 struct shmem_inode_info *info;
4469 info = alloc_inode_sb(sb, shmem_inode_cachep, GFP_KERNEL);
4470 if (!info)
4471 return NULL;
4472 return &info->vfs_inode;
4473}
4474
4475static void shmem_free_in_core_inode(struct inode *inode)
4476{
4477 if (S_ISLNK(inode->i_mode))
4478 kfree(inode->i_link);
4479 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
4480}
4481
4482static void shmem_destroy_inode(struct inode *inode)
4483{
4484 if (S_ISREG(inode->i_mode))
4485 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
4486 if (S_ISDIR(inode->i_mode))
4487 simple_offset_destroy(shmem_get_offset_ctx(inode));
4488}
4489
4490static void shmem_init_inode(void *foo)
4491{
4492 struct shmem_inode_info *info = foo;
4493 inode_init_once(&info->vfs_inode);
4494}
4495
4496static void __init shmem_init_inodecache(void)
4497{
4498 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
4499 sizeof(struct shmem_inode_info),
4500 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
4501}
4502
4503static void __init shmem_destroy_inodecache(void)
4504{
4505 kmem_cache_destroy(shmem_inode_cachep);
4506}
4507
4508/* Keep the page in page cache instead of truncating it */
4509static int shmem_error_remove_folio(struct address_space *mapping,
4510 struct folio *folio)
4511{
4512 return 0;
4513}
4514
4515static const struct address_space_operations shmem_aops = {
4516 .writepage = shmem_writepage,
4517 .dirty_folio = noop_dirty_folio,
4518#ifdef CONFIG_TMPFS
4519 .write_begin = shmem_write_begin,
4520 .write_end = shmem_write_end,
4521#endif
4522#ifdef CONFIG_MIGRATION
4523 .migrate_folio = migrate_folio,
4524#endif
4525 .error_remove_folio = shmem_error_remove_folio,
4526};
4527
4528static const struct file_operations shmem_file_operations = {
4529 .mmap = shmem_mmap,
4530 .open = shmem_file_open,
4531 .get_unmapped_area = shmem_get_unmapped_area,
4532#ifdef CONFIG_TMPFS
4533 .llseek = shmem_file_llseek,
4534 .read_iter = shmem_file_read_iter,
4535 .write_iter = shmem_file_write_iter,
4536 .fsync = noop_fsync,
4537 .splice_read = shmem_file_splice_read,
4538 .splice_write = iter_file_splice_write,
4539 .fallocate = shmem_fallocate,
4540#endif
4541};
4542
4543static const struct inode_operations shmem_inode_operations = {
4544 .getattr = shmem_getattr,
4545 .setattr = shmem_setattr,
4546#ifdef CONFIG_TMPFS_XATTR
4547 .listxattr = shmem_listxattr,
4548 .set_acl = simple_set_acl,
4549 .fileattr_get = shmem_fileattr_get,
4550 .fileattr_set = shmem_fileattr_set,
4551#endif
4552};
4553
4554static const struct inode_operations shmem_dir_inode_operations = {
4555#ifdef CONFIG_TMPFS
4556 .getattr = shmem_getattr,
4557 .create = shmem_create,
4558 .lookup = simple_lookup,
4559 .link = shmem_link,
4560 .unlink = shmem_unlink,
4561 .symlink = shmem_symlink,
4562 .mkdir = shmem_mkdir,
4563 .rmdir = shmem_rmdir,
4564 .mknod = shmem_mknod,
4565 .rename = shmem_rename2,
4566 .tmpfile = shmem_tmpfile,
4567 .get_offset_ctx = shmem_get_offset_ctx,
4568#endif
4569#ifdef CONFIG_TMPFS_XATTR
4570 .listxattr = shmem_listxattr,
4571 .fileattr_get = shmem_fileattr_get,
4572 .fileattr_set = shmem_fileattr_set,
4573#endif
4574#ifdef CONFIG_TMPFS_POSIX_ACL
4575 .setattr = shmem_setattr,
4576 .set_acl = simple_set_acl,
4577#endif
4578};
4579
4580static const struct inode_operations shmem_special_inode_operations = {
4581 .getattr = shmem_getattr,
4582#ifdef CONFIG_TMPFS_XATTR
4583 .listxattr = shmem_listxattr,
4584#endif
4585#ifdef CONFIG_TMPFS_POSIX_ACL
4586 .setattr = shmem_setattr,
4587 .set_acl = simple_set_acl,
4588#endif
4589};
4590
4591static const struct super_operations shmem_ops = {
4592 .alloc_inode = shmem_alloc_inode,
4593 .free_inode = shmem_free_in_core_inode,
4594 .destroy_inode = shmem_destroy_inode,
4595#ifdef CONFIG_TMPFS
4596 .statfs = shmem_statfs,
4597 .show_options = shmem_show_options,
4598#endif
4599#ifdef CONFIG_TMPFS_QUOTA
4600 .get_dquots = shmem_get_dquots,
4601#endif
4602 .evict_inode = shmem_evict_inode,
4603 .drop_inode = generic_delete_inode,
4604 .put_super = shmem_put_super,
4605#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4606 .nr_cached_objects = shmem_unused_huge_count,
4607 .free_cached_objects = shmem_unused_huge_scan,
4608#endif
4609};
4610
4611static const struct vm_operations_struct shmem_vm_ops = {
4612 .fault = shmem_fault,
4613 .map_pages = filemap_map_pages,
4614#ifdef CONFIG_NUMA
4615 .set_policy = shmem_set_policy,
4616 .get_policy = shmem_get_policy,
4617#endif
4618};
4619
4620static const struct vm_operations_struct shmem_anon_vm_ops = {
4621 .fault = shmem_fault,
4622 .map_pages = filemap_map_pages,
4623#ifdef CONFIG_NUMA
4624 .set_policy = shmem_set_policy,
4625 .get_policy = shmem_get_policy,
4626#endif
4627};
4628
4629int shmem_init_fs_context(struct fs_context *fc)
4630{
4631 struct shmem_options *ctx;
4632
4633 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
4634 if (!ctx)
4635 return -ENOMEM;
4636
4637 ctx->mode = 0777 | S_ISVTX;
4638 ctx->uid = current_fsuid();
4639 ctx->gid = current_fsgid();
4640
4641 fc->fs_private = ctx;
4642 fc->ops = &shmem_fs_context_ops;
4643 return 0;
4644}
4645
4646static struct file_system_type shmem_fs_type = {
4647 .owner = THIS_MODULE,
4648 .name = "tmpfs",
4649 .init_fs_context = shmem_init_fs_context,
4650#ifdef CONFIG_TMPFS
4651 .parameters = shmem_fs_parameters,
4652#endif
4653 .kill_sb = kill_litter_super,
4654 .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP,
4655};
4656
4657void __init shmem_init(void)
4658{
4659 int error;
4660
4661 shmem_init_inodecache();
4662
4663#ifdef CONFIG_TMPFS_QUOTA
4664 error = register_quota_format(&shmem_quota_format);
4665 if (error < 0) {
4666 pr_err("Could not register quota format\n");
4667 goto out3;
4668 }
4669#endif
4670
4671 error = register_filesystem(&shmem_fs_type);
4672 if (error) {
4673 pr_err("Could not register tmpfs\n");
4674 goto out2;
4675 }
4676
4677 shm_mnt = kern_mount(&shmem_fs_type);
4678 if (IS_ERR(shm_mnt)) {
4679 error = PTR_ERR(shm_mnt);
4680 pr_err("Could not kern_mount tmpfs\n");
4681 goto out1;
4682 }
4683
4684#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4685 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
4686 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4687 else
4688 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
4689#endif
4690 return;
4691
4692out1:
4693 unregister_filesystem(&shmem_fs_type);
4694out2:
4695#ifdef CONFIG_TMPFS_QUOTA
4696 unregister_quota_format(&shmem_quota_format);
4697out3:
4698#endif
4699 shmem_destroy_inodecache();
4700 shm_mnt = ERR_PTR(error);
4701}
4702
4703#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
4704static ssize_t shmem_enabled_show(struct kobject *kobj,
4705 struct kobj_attribute *attr, char *buf)
4706{
4707 static const int values[] = {
4708 SHMEM_HUGE_ALWAYS,
4709 SHMEM_HUGE_WITHIN_SIZE,
4710 SHMEM_HUGE_ADVISE,
4711 SHMEM_HUGE_NEVER,
4712 SHMEM_HUGE_DENY,
4713 SHMEM_HUGE_FORCE,
4714 };
4715 int len = 0;
4716 int i;
4717
4718 for (i = 0; i < ARRAY_SIZE(values); i++) {
4719 len += sysfs_emit_at(buf, len,
4720 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
4721 i ? " " : "", shmem_format_huge(values[i]));
4722 }
4723 len += sysfs_emit_at(buf, len, "\n");
4724
4725 return len;
4726}
4727
4728static ssize_t shmem_enabled_store(struct kobject *kobj,
4729 struct kobj_attribute *attr, const char *buf, size_t count)
4730{
4731 char tmp[16];
4732 int huge;
4733
4734 if (count + 1 > sizeof(tmp))
4735 return -EINVAL;
4736 memcpy(tmp, buf, count);
4737 tmp[count] = '\0';
4738 if (count && tmp[count - 1] == '\n')
4739 tmp[count - 1] = '\0';
4740
4741 huge = shmem_parse_huge(tmp);
4742 if (huge == -EINVAL)
4743 return -EINVAL;
4744 if (!has_transparent_hugepage() &&
4745 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4746 return -EINVAL;
4747
4748 shmem_huge = huge;
4749 if (shmem_huge > SHMEM_HUGE_DENY)
4750 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4751 return count;
4752}
4753
4754struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
4755#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4756
4757#else /* !CONFIG_SHMEM */
4758
4759/*
4760 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4761 *
4762 * This is intended for small system where the benefits of the full
4763 * shmem code (swap-backed and resource-limited) are outweighed by
4764 * their complexity. On systems without swap this code should be
4765 * effectively equivalent, but much lighter weight.
4766 */
4767
4768static struct file_system_type shmem_fs_type = {
4769 .name = "tmpfs",
4770 .init_fs_context = ramfs_init_fs_context,
4771 .parameters = ramfs_fs_parameters,
4772 .kill_sb = ramfs_kill_sb,
4773 .fs_flags = FS_USERNS_MOUNT,
4774};
4775
4776void __init shmem_init(void)
4777{
4778 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4779
4780 shm_mnt = kern_mount(&shmem_fs_type);
4781 BUG_ON(IS_ERR(shm_mnt));
4782}
4783
4784int shmem_unuse(unsigned int type)
4785{
4786 return 0;
4787}
4788
4789int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
4790{
4791 return 0;
4792}
4793
4794void shmem_unlock_mapping(struct address_space *mapping)
4795{
4796}
4797
4798#ifdef CONFIG_MMU
4799unsigned long shmem_get_unmapped_area(struct file *file,
4800 unsigned long addr, unsigned long len,
4801 unsigned long pgoff, unsigned long flags)
4802{
4803 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4804}
4805#endif
4806
4807void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4808{
4809 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4810}
4811EXPORT_SYMBOL_GPL(shmem_truncate_range);
4812
4813#define shmem_vm_ops generic_file_vm_ops
4814#define shmem_anon_vm_ops generic_file_vm_ops
4815#define shmem_file_operations ramfs_file_operations
4816#define shmem_acct_size(flags, size) 0
4817#define shmem_unacct_size(flags, size) do {} while (0)
4818
4819static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
4820 struct super_block *sb, struct inode *dir,
4821 umode_t mode, dev_t dev, unsigned long flags)
4822{
4823 struct inode *inode = ramfs_get_inode(sb, dir, mode, dev);
4824 return inode ? inode : ERR_PTR(-ENOSPC);
4825}
4826
4827#endif /* CONFIG_SHMEM */
4828
4829/* common code */
4830
4831static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
4832 loff_t size, unsigned long flags, unsigned int i_flags)
4833{
4834 struct inode *inode;
4835 struct file *res;
4836
4837 if (IS_ERR(mnt))
4838 return ERR_CAST(mnt);
4839
4840 if (size < 0 || size > MAX_LFS_FILESIZE)
4841 return ERR_PTR(-EINVAL);
4842
4843 if (shmem_acct_size(flags, size))
4844 return ERR_PTR(-ENOMEM);
4845
4846 if (is_idmapped_mnt(mnt))
4847 return ERR_PTR(-EINVAL);
4848
4849 inode = shmem_get_inode(&nop_mnt_idmap, mnt->mnt_sb, NULL,
4850 S_IFREG | S_IRWXUGO, 0, flags);
4851 if (IS_ERR(inode)) {
4852 shmem_unacct_size(flags, size);
4853 return ERR_CAST(inode);
4854 }
4855 inode->i_flags |= i_flags;
4856 inode->i_size = size;
4857 clear_nlink(inode); /* It is unlinked */
4858 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4859 if (!IS_ERR(res))
4860 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4861 &shmem_file_operations);
4862 if (IS_ERR(res))
4863 iput(inode);
4864 return res;
4865}
4866
4867/**
4868 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4869 * kernel internal. There will be NO LSM permission checks against the
4870 * underlying inode. So users of this interface must do LSM checks at a
4871 * higher layer. The users are the big_key and shm implementations. LSM
4872 * checks are provided at the key or shm level rather than the inode.
4873 * @name: name for dentry (to be seen in /proc/<pid>/maps
4874 * @size: size to be set for the file
4875 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4876 */
4877struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4878{
4879 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4880}
4881EXPORT_SYMBOL_GPL(shmem_kernel_file_setup);
4882
4883/**
4884 * shmem_file_setup - get an unlinked file living in tmpfs
4885 * @name: name for dentry (to be seen in /proc/<pid>/maps
4886 * @size: size to be set for the file
4887 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4888 */
4889struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4890{
4891 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4892}
4893EXPORT_SYMBOL_GPL(shmem_file_setup);
4894
4895/**
4896 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4897 * @mnt: the tmpfs mount where the file will be created
4898 * @name: name for dentry (to be seen in /proc/<pid>/maps
4899 * @size: size to be set for the file
4900 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4901 */
4902struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4903 loff_t size, unsigned long flags)
4904{
4905 return __shmem_file_setup(mnt, name, size, flags, 0);
4906}
4907EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4908
4909/**
4910 * shmem_zero_setup - setup a shared anonymous mapping
4911 * @vma: the vma to be mmapped is prepared by do_mmap
4912 */
4913int shmem_zero_setup(struct vm_area_struct *vma)
4914{
4915 struct file *file;
4916 loff_t size = vma->vm_end - vma->vm_start;
4917
4918 /*
4919 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4920 * between XFS directory reading and selinux: since this file is only
4921 * accessible to the user through its mapping, use S_PRIVATE flag to
4922 * bypass file security, in the same way as shmem_kernel_file_setup().
4923 */
4924 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4925 if (IS_ERR(file))
4926 return PTR_ERR(file);
4927
4928 if (vma->vm_file)
4929 fput(vma->vm_file);
4930 vma->vm_file = file;
4931 vma->vm_ops = &shmem_anon_vm_ops;
4932
4933 return 0;
4934}
4935
4936/**
4937 * shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
4938 * @mapping: the folio's address_space
4939 * @index: the folio index
4940 * @gfp: the page allocator flags to use if allocating
4941 *
4942 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4943 * with any new page allocations done using the specified allocation flags.
4944 * But read_cache_page_gfp() uses the ->read_folio() method: which does not
4945 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4946 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4947 *
4948 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4949 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4950 */
4951struct folio *shmem_read_folio_gfp(struct address_space *mapping,
4952 pgoff_t index, gfp_t gfp)
4953{
4954#ifdef CONFIG_SHMEM
4955 struct inode *inode = mapping->host;
4956 struct folio *folio;
4957 int error;
4958
4959 error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
4960 gfp, NULL, NULL);
4961 if (error)
4962 return ERR_PTR(error);
4963
4964 folio_unlock(folio);
4965 return folio;
4966#else
4967 /*
4968 * The tiny !SHMEM case uses ramfs without swap
4969 */
4970 return mapping_read_folio_gfp(mapping, index, gfp);
4971#endif
4972}
4973EXPORT_SYMBOL_GPL(shmem_read_folio_gfp);
4974
4975struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4976 pgoff_t index, gfp_t gfp)
4977{
4978 struct folio *folio = shmem_read_folio_gfp(mapping, index, gfp);
4979 struct page *page;
4980
4981 if (IS_ERR(folio))
4982 return &folio->page;
4983
4984 page = folio_file_page(folio, index);
4985 if (PageHWPoison(page)) {
4986 folio_put(folio);
4987 return ERR_PTR(-EIO);
4988 }
4989
4990 return page;
4991}
4992EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);