2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
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
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>
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
21 * This file is released under the GPL.
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>
32 #include <linux/random.h>
33 #include <linux/sched/signal.h>
34 #include <linux/export.h>
35 #include <linux/swap.h>
36 #include <linux/uio.h>
37 #include <linux/hugetlb.h>
38 #include <linux/fs_parser.h>
39 #include <linux/swapfile.h>
42 static struct vfsmount *shm_mnt;
46 * This virtual memory filesystem is heavily based on the ramfs. It
47 * extends ramfs by the ability to use swap and honor resource limits
48 * which makes it a completely usable filesystem.
51 #include <linux/xattr.h>
52 #include <linux/exportfs.h>
53 #include <linux/posix_acl.h>
54 #include <linux/posix_acl_xattr.h>
55 #include <linux/mman.h>
56 #include <linux/string.h>
57 #include <linux/slab.h>
58 #include <linux/backing-dev.h>
59 #include <linux/shmem_fs.h>
60 #include <linux/writeback.h>
61 #include <linux/pagevec.h>
62 #include <linux/percpu_counter.h>
63 #include <linux/falloc.h>
64 #include <linux/splice.h>
65 #include <linux/security.h>
66 #include <linux/swapops.h>
67 #include <linux/mempolicy.h>
68 #include <linux/namei.h>
69 #include <linux/ctype.h>
70 #include <linux/migrate.h>
71 #include <linux/highmem.h>
72 #include <linux/seq_file.h>
73 #include <linux/magic.h>
74 #include <linux/syscalls.h>
75 #include <linux/fcntl.h>
76 #include <uapi/linux/memfd.h>
77 #include <linux/userfaultfd_k.h>
78 #include <linux/rmap.h>
79 #include <linux/uuid.h>
81 #include <linux/uaccess.h>
85 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
86 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
88 /* Pretend that each entry is of this size in directory's i_size */
89 #define BOGO_DIRENT_SIZE 20
91 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
92 #define SHORT_SYMLINK_LEN 128
95 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
96 * inode->i_private (with i_rwsem making sure that it has only one user at
97 * a time): we would prefer not to enlarge the shmem inode just for that.
100 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
101 pgoff_t start; /* start of range currently being fallocated */
102 pgoff_t next; /* the next page offset to be fallocated */
103 pgoff_t nr_falloced; /* how many new pages have been fallocated */
104 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
107 struct shmem_options {
108 unsigned long long blocks;
109 unsigned long long inodes;
110 struct mempolicy *mpol;
117 #define SHMEM_SEEN_BLOCKS 1
118 #define SHMEM_SEEN_INODES 2
119 #define SHMEM_SEEN_HUGE 4
120 #define SHMEM_SEEN_INUMS 8
124 static unsigned long shmem_default_max_blocks(void)
126 return totalram_pages() / 2;
129 static unsigned long shmem_default_max_inodes(void)
131 unsigned long nr_pages = totalram_pages();
133 return min(nr_pages - totalhigh_pages(), nr_pages / 2);
137 static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
138 struct folio **foliop, enum sgp_type sgp,
139 gfp_t gfp, struct vm_area_struct *vma,
140 vm_fault_t *fault_type);
141 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
142 struct page **pagep, enum sgp_type sgp,
143 gfp_t gfp, struct vm_area_struct *vma,
144 struct vm_fault *vmf, vm_fault_t *fault_type);
146 int shmem_getpage(struct inode *inode, pgoff_t index,
147 struct page **pagep, enum sgp_type sgp)
149 return shmem_getpage_gfp(inode, index, pagep, sgp,
150 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
153 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
155 return sb->s_fs_info;
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 ...
164 static inline int shmem_acct_size(unsigned long flags, loff_t size)
166 return (flags & VM_NORESERVE) ?
167 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
170 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
172 if (!(flags & VM_NORESERVE))
173 vm_unacct_memory(VM_ACCT(size));
176 static inline int shmem_reacct_size(unsigned long flags,
177 loff_t oldsize, loff_t newsize)
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));
190 * ... whereas tmpfs objects are accounted incrementally as
191 * pages are allocated, in order to allow large sparse files.
192 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
193 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
195 static inline int shmem_acct_block(unsigned long flags, long pages)
197 if (!(flags & VM_NORESERVE))
200 return security_vm_enough_memory_mm(current->mm,
201 pages * VM_ACCT(PAGE_SIZE));
204 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
206 if (flags & VM_NORESERVE)
207 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
210 static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
212 struct shmem_inode_info *info = SHMEM_I(inode);
213 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
215 if (shmem_acct_block(info->flags, pages))
218 if (sbinfo->max_blocks) {
219 if (percpu_counter_compare(&sbinfo->used_blocks,
220 sbinfo->max_blocks - pages) > 0)
222 percpu_counter_add(&sbinfo->used_blocks, pages);
228 shmem_unacct_blocks(info->flags, pages);
232 static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
234 struct shmem_inode_info *info = SHMEM_I(inode);
235 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
237 if (sbinfo->max_blocks)
238 percpu_counter_sub(&sbinfo->used_blocks, pages);
239 shmem_unacct_blocks(info->flags, pages);
242 static const struct super_operations shmem_ops;
243 const struct address_space_operations shmem_aops;
244 static const struct file_operations shmem_file_operations;
245 static const struct inode_operations shmem_inode_operations;
246 static const struct inode_operations shmem_dir_inode_operations;
247 static const struct inode_operations shmem_special_inode_operations;
248 static const struct vm_operations_struct shmem_vm_ops;
249 static struct file_system_type shmem_fs_type;
251 bool vma_is_shmem(struct vm_area_struct *vma)
253 return vma->vm_ops == &shmem_vm_ops;
256 static LIST_HEAD(shmem_swaplist);
257 static DEFINE_MUTEX(shmem_swaplist_mutex);
260 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
261 * produces a novel ino for the newly allocated inode.
263 * It may also be called when making a hard link to permit the space needed by
264 * each dentry. However, in that case, no new inode number is needed since that
265 * internally draws from another pool of inode numbers (currently global
266 * get_next_ino()). This case is indicated by passing NULL as inop.
268 #define SHMEM_INO_BATCH 1024
269 static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
271 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
274 if (!(sb->s_flags & SB_KERNMOUNT)) {
275 raw_spin_lock(&sbinfo->stat_lock);
276 if (sbinfo->max_inodes) {
277 if (!sbinfo->free_inodes) {
278 raw_spin_unlock(&sbinfo->stat_lock);
281 sbinfo->free_inodes--;
284 ino = sbinfo->next_ino++;
285 if (unlikely(is_zero_ino(ino)))
286 ino = sbinfo->next_ino++;
287 if (unlikely(!sbinfo->full_inums &&
290 * Emulate get_next_ino uint wraparound for
293 if (IS_ENABLED(CONFIG_64BIT))
294 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
295 __func__, MINOR(sb->s_dev));
296 sbinfo->next_ino = 1;
297 ino = sbinfo->next_ino++;
301 raw_spin_unlock(&sbinfo->stat_lock);
304 * __shmem_file_setup, one of our callers, is lock-free: it
305 * doesn't hold stat_lock in shmem_reserve_inode since
306 * max_inodes is always 0, and is called from potentially
307 * unknown contexts. As such, use a per-cpu batched allocator
308 * which doesn't require the per-sb stat_lock unless we are at
309 * the batch boundary.
311 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
312 * shmem mounts are not exposed to userspace, so we don't need
313 * to worry about things like glibc compatibility.
317 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
319 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
320 raw_spin_lock(&sbinfo->stat_lock);
321 ino = sbinfo->next_ino;
322 sbinfo->next_ino += SHMEM_INO_BATCH;
323 raw_spin_unlock(&sbinfo->stat_lock);
324 if (unlikely(is_zero_ino(ino)))
335 static void shmem_free_inode(struct super_block *sb)
337 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
338 if (sbinfo->max_inodes) {
339 raw_spin_lock(&sbinfo->stat_lock);
340 sbinfo->free_inodes++;
341 raw_spin_unlock(&sbinfo->stat_lock);
346 * shmem_recalc_inode - recalculate the block usage of an inode
347 * @inode: inode to recalc
349 * We have to calculate the free blocks since the mm can drop
350 * undirtied hole pages behind our back.
352 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
353 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
355 * It has to be called with the spinlock held.
357 static void shmem_recalc_inode(struct inode *inode)
359 struct shmem_inode_info *info = SHMEM_I(inode);
362 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
364 info->alloced -= freed;
365 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
366 shmem_inode_unacct_blocks(inode, freed);
370 bool shmem_charge(struct inode *inode, long pages)
372 struct shmem_inode_info *info = SHMEM_I(inode);
375 if (!shmem_inode_acct_block(inode, pages))
378 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
379 inode->i_mapping->nrpages += pages;
381 spin_lock_irqsave(&info->lock, flags);
382 info->alloced += pages;
383 inode->i_blocks += pages * BLOCKS_PER_PAGE;
384 shmem_recalc_inode(inode);
385 spin_unlock_irqrestore(&info->lock, flags);
390 void shmem_uncharge(struct inode *inode, long pages)
392 struct shmem_inode_info *info = SHMEM_I(inode);
395 /* nrpages adjustment done by __filemap_remove_folio() or caller */
397 spin_lock_irqsave(&info->lock, flags);
398 info->alloced -= pages;
399 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
400 shmem_recalc_inode(inode);
401 spin_unlock_irqrestore(&info->lock, flags);
403 shmem_inode_unacct_blocks(inode, pages);
407 * Replace item expected in xarray by a new item, while holding xa_lock.
409 static int shmem_replace_entry(struct address_space *mapping,
410 pgoff_t index, void *expected, void *replacement)
412 XA_STATE(xas, &mapping->i_pages, index);
415 VM_BUG_ON(!expected);
416 VM_BUG_ON(!replacement);
417 item = xas_load(&xas);
418 if (item != expected)
420 xas_store(&xas, replacement);
425 * Sometimes, before we decide whether to proceed or to fail, we must check
426 * that an entry was not already brought back from swap by a racing thread.
428 * Checking page is not enough: by the time a SwapCache page is locked, it
429 * might be reused, and again be SwapCache, using the same swap as before.
431 static bool shmem_confirm_swap(struct address_space *mapping,
432 pgoff_t index, swp_entry_t swap)
434 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
438 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
441 * disables huge pages for the mount;
443 * enables huge pages for the mount;
444 * SHMEM_HUGE_WITHIN_SIZE:
445 * only allocate huge pages if the page will be fully within i_size,
446 * also respect fadvise()/madvise() hints;
448 * only allocate huge pages if requested with fadvise()/madvise();
451 #define SHMEM_HUGE_NEVER 0
452 #define SHMEM_HUGE_ALWAYS 1
453 #define SHMEM_HUGE_WITHIN_SIZE 2
454 #define SHMEM_HUGE_ADVISE 3
458 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
461 * disables huge on shm_mnt and all mounts, for emergency use;
463 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
466 #define SHMEM_HUGE_DENY (-1)
467 #define SHMEM_HUGE_FORCE (-2)
469 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
470 /* ifdef here to avoid bloating shmem.o when not necessary */
472 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
474 bool shmem_is_huge(struct vm_area_struct *vma,
475 struct inode *inode, pgoff_t index)
479 if (!S_ISREG(inode->i_mode))
481 if (shmem_huge == SHMEM_HUGE_DENY)
483 if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
484 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
486 if (shmem_huge == SHMEM_HUGE_FORCE)
489 switch (SHMEM_SB(inode->i_sb)->huge) {
490 case SHMEM_HUGE_ALWAYS:
492 case SHMEM_HUGE_WITHIN_SIZE:
493 index = round_up(index + 1, HPAGE_PMD_NR);
494 i_size = round_up(i_size_read(inode), PAGE_SIZE);
495 if (i_size >> PAGE_SHIFT >= index)
498 case SHMEM_HUGE_ADVISE:
499 if (vma && (vma->vm_flags & VM_HUGEPAGE))
507 #if defined(CONFIG_SYSFS)
508 static int shmem_parse_huge(const char *str)
510 if (!strcmp(str, "never"))
511 return SHMEM_HUGE_NEVER;
512 if (!strcmp(str, "always"))
513 return SHMEM_HUGE_ALWAYS;
514 if (!strcmp(str, "within_size"))
515 return SHMEM_HUGE_WITHIN_SIZE;
516 if (!strcmp(str, "advise"))
517 return SHMEM_HUGE_ADVISE;
518 if (!strcmp(str, "deny"))
519 return SHMEM_HUGE_DENY;
520 if (!strcmp(str, "force"))
521 return SHMEM_HUGE_FORCE;
526 #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
527 static const char *shmem_format_huge(int huge)
530 case SHMEM_HUGE_NEVER:
532 case SHMEM_HUGE_ALWAYS:
534 case SHMEM_HUGE_WITHIN_SIZE:
535 return "within_size";
536 case SHMEM_HUGE_ADVISE:
538 case SHMEM_HUGE_DENY:
540 case SHMEM_HUGE_FORCE:
549 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
550 struct shrink_control *sc, unsigned long nr_to_split)
552 LIST_HEAD(list), *pos, *next;
553 LIST_HEAD(to_remove);
555 struct shmem_inode_info *info;
557 unsigned long batch = sc ? sc->nr_to_scan : 128;
560 if (list_empty(&sbinfo->shrinklist))
563 spin_lock(&sbinfo->shrinklist_lock);
564 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
565 info = list_entry(pos, struct shmem_inode_info, shrinklist);
568 inode = igrab(&info->vfs_inode);
570 /* inode is about to be evicted */
572 list_del_init(&info->shrinklist);
576 /* Check if there's anything to gain */
577 if (round_up(inode->i_size, PAGE_SIZE) ==
578 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
579 list_move(&info->shrinklist, &to_remove);
583 list_move(&info->shrinklist, &list);
585 sbinfo->shrinklist_len--;
589 spin_unlock(&sbinfo->shrinklist_lock);
591 list_for_each_safe(pos, next, &to_remove) {
592 info = list_entry(pos, struct shmem_inode_info, shrinklist);
593 inode = &info->vfs_inode;
594 list_del_init(&info->shrinklist);
598 list_for_each_safe(pos, next, &list) {
602 info = list_entry(pos, struct shmem_inode_info, shrinklist);
603 inode = &info->vfs_inode;
605 if (nr_to_split && split >= nr_to_split)
608 index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
609 folio = filemap_get_folio(inode->i_mapping, index);
613 /* No huge page at the end of the file: nothing to split */
614 if (!folio_test_large(folio)) {
620 * Move the inode on the list back to shrinklist if we failed
621 * to lock the page at this time.
623 * Waiting for the lock may lead to deadlock in the
626 if (!folio_trylock(folio)) {
631 ret = split_huge_page(&folio->page);
635 /* If split failed move the inode on the list back to shrinklist */
641 list_del_init(&info->shrinklist);
645 * Make sure the inode is either on the global list or deleted
646 * from any local list before iput() since it could be deleted
647 * in another thread once we put the inode (then the local list
650 spin_lock(&sbinfo->shrinklist_lock);
651 list_move(&info->shrinklist, &sbinfo->shrinklist);
652 sbinfo->shrinklist_len++;
653 spin_unlock(&sbinfo->shrinklist_lock);
661 static long shmem_unused_huge_scan(struct super_block *sb,
662 struct shrink_control *sc)
664 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
666 if (!READ_ONCE(sbinfo->shrinklist_len))
669 return shmem_unused_huge_shrink(sbinfo, sc, 0);
672 static long shmem_unused_huge_count(struct super_block *sb,
673 struct shrink_control *sc)
675 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
676 return READ_ONCE(sbinfo->shrinklist_len);
678 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
680 #define shmem_huge SHMEM_HUGE_DENY
682 bool shmem_is_huge(struct vm_area_struct *vma,
683 struct inode *inode, pgoff_t index)
688 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
689 struct shrink_control *sc, unsigned long nr_to_split)
693 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
696 * Like filemap_add_folio, but error if expected item has gone.
698 static int shmem_add_to_page_cache(struct folio *folio,
699 struct address_space *mapping,
700 pgoff_t index, void *expected, gfp_t gfp,
701 struct mm_struct *charge_mm)
703 XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
704 long nr = folio_nr_pages(folio);
707 VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
708 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
709 VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
710 VM_BUG_ON(expected && folio_test_large(folio));
712 folio_ref_add(folio, nr);
713 folio->mapping = mapping;
714 folio->index = index;
716 if (!folio_test_swapcache(folio)) {
717 error = mem_cgroup_charge(folio, charge_mm, gfp);
719 if (folio_test_pmd_mappable(folio)) {
720 count_vm_event(THP_FILE_FALLBACK);
721 count_vm_event(THP_FILE_FALLBACK_CHARGE);
726 folio_throttle_swaprate(folio, gfp);
730 if (expected != xas_find_conflict(&xas)) {
731 xas_set_err(&xas, -EEXIST);
734 if (expected && xas_find_conflict(&xas)) {
735 xas_set_err(&xas, -EEXIST);
738 xas_store(&xas, folio);
741 if (folio_test_pmd_mappable(folio)) {
742 count_vm_event(THP_FILE_ALLOC);
743 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr);
745 mapping->nrpages += nr;
746 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);
747 __lruvec_stat_mod_folio(folio, NR_SHMEM, nr);
749 xas_unlock_irq(&xas);
750 } while (xas_nomem(&xas, gfp));
752 if (xas_error(&xas)) {
753 error = xas_error(&xas);
759 folio->mapping = NULL;
760 folio_ref_sub(folio, nr);
765 * Like delete_from_page_cache, but substitutes swap for page.
767 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
769 struct address_space *mapping = page->mapping;
772 VM_BUG_ON_PAGE(PageCompound(page), page);
774 xa_lock_irq(&mapping->i_pages);
775 error = shmem_replace_entry(mapping, page->index, page, radswap);
776 page->mapping = NULL;
778 __dec_lruvec_page_state(page, NR_FILE_PAGES);
779 __dec_lruvec_page_state(page, NR_SHMEM);
780 xa_unlock_irq(&mapping->i_pages);
786 * Remove swap entry from page cache, free the swap and its page cache.
788 static int shmem_free_swap(struct address_space *mapping,
789 pgoff_t index, void *radswap)
793 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
796 free_swap_and_cache(radix_to_swp_entry(radswap));
801 * Determine (in bytes) how many of the shmem object's pages mapped by the
802 * given offsets are swapped out.
804 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
805 * as long as the inode doesn't go away and racy results are not a problem.
807 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
808 pgoff_t start, pgoff_t end)
810 XA_STATE(xas, &mapping->i_pages, start);
812 unsigned long swapped = 0;
815 xas_for_each(&xas, page, end - 1) {
816 if (xas_retry(&xas, page))
818 if (xa_is_value(page))
821 if (need_resched()) {
829 return swapped << PAGE_SHIFT;
833 * Determine (in bytes) how many of the shmem object's pages mapped by the
834 * given vma is swapped out.
836 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
837 * as long as the inode doesn't go away and racy results are not a problem.
839 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
841 struct inode *inode = file_inode(vma->vm_file);
842 struct shmem_inode_info *info = SHMEM_I(inode);
843 struct address_space *mapping = inode->i_mapping;
844 unsigned long swapped;
846 /* Be careful as we don't hold info->lock */
847 swapped = READ_ONCE(info->swapped);
850 * The easier cases are when the shmem object has nothing in swap, or
851 * the vma maps it whole. Then we can simply use the stats that we
857 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
858 return swapped << PAGE_SHIFT;
860 /* Here comes the more involved part */
861 return shmem_partial_swap_usage(mapping, vma->vm_pgoff,
862 vma->vm_pgoff + vma_pages(vma));
866 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
868 void shmem_unlock_mapping(struct address_space *mapping)
870 struct folio_batch fbatch;
873 folio_batch_init(&fbatch);
875 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
877 while (!mapping_unevictable(mapping) &&
878 filemap_get_folios(mapping, &index, ~0UL, &fbatch)) {
879 check_move_unevictable_folios(&fbatch);
880 folio_batch_release(&fbatch);
885 static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
891 * At first avoid shmem_getpage(,,,SGP_READ): that fails
892 * beyond i_size, and reports fallocated pages as holes.
894 folio = __filemap_get_folio(inode->i_mapping, index,
895 FGP_ENTRY | FGP_LOCK, 0);
896 if (!xa_is_value(folio))
899 * But read a page back from swap if any of it is within i_size
900 * (although in some cases this is just a waste of time).
903 shmem_getpage(inode, index, &page, SGP_READ);
904 return page ? page_folio(page) : NULL;
908 * Remove range of pages and swap entries from page cache, and free them.
909 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
911 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
914 struct address_space *mapping = inode->i_mapping;
915 struct shmem_inode_info *info = SHMEM_I(inode);
916 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
917 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
918 struct folio_batch fbatch;
919 pgoff_t indices[PAGEVEC_SIZE];
922 long nr_swaps_freed = 0;
927 end = -1; /* unsigned, so actually very big */
929 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
930 info->fallocend = start;
932 folio_batch_init(&fbatch);
934 while (index < end && find_lock_entries(mapping, index, end - 1,
936 for (i = 0; i < folio_batch_count(&fbatch); i++) {
937 folio = fbatch.folios[i];
941 if (xa_is_value(folio)) {
944 nr_swaps_freed += !shmem_free_swap(mapping,
948 index += folio_nr_pages(folio) - 1;
950 if (!unfalloc || !folio_test_uptodate(folio))
951 truncate_inode_folio(mapping, folio);
954 folio_batch_remove_exceptionals(&fbatch);
955 folio_batch_release(&fbatch);
960 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
961 folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT);
963 same_folio = lend < folio_pos(folio) + folio_size(folio);
964 folio_mark_dirty(folio);
965 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
966 start = folio->index + folio_nr_pages(folio);
976 folio = shmem_get_partial_folio(inode, lend >> PAGE_SHIFT);
978 folio_mark_dirty(folio);
979 if (!truncate_inode_partial_folio(folio, lstart, lend))
986 while (index < end) {
989 if (!find_get_entries(mapping, index, end - 1, &fbatch,
991 /* If all gone or hole-punch or unfalloc, we're done */
992 if (index == start || end != -1)
994 /* But if truncating, restart to make sure all gone */
998 for (i = 0; i < folio_batch_count(&fbatch); i++) {
999 folio = fbatch.folios[i];
1002 if (xa_is_value(folio)) {
1005 if (shmem_free_swap(mapping, index, folio)) {
1006 /* Swap was replaced by page: retry */
1016 if (!unfalloc || !folio_test_uptodate(folio)) {
1017 if (folio_mapping(folio) != mapping) {
1018 /* Page was replaced by swap: retry */
1019 folio_unlock(folio);
1023 VM_BUG_ON_FOLIO(folio_test_writeback(folio),
1025 truncate_inode_folio(mapping, folio);
1027 index = folio->index + folio_nr_pages(folio) - 1;
1028 folio_unlock(folio);
1030 folio_batch_remove_exceptionals(&fbatch);
1031 folio_batch_release(&fbatch);
1035 spin_lock_irq(&info->lock);
1036 info->swapped -= nr_swaps_freed;
1037 shmem_recalc_inode(inode);
1038 spin_unlock_irq(&info->lock);
1041 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1043 shmem_undo_range(inode, lstart, lend, false);
1044 inode->i_ctime = inode->i_mtime = current_time(inode);
1046 EXPORT_SYMBOL_GPL(shmem_truncate_range);
1048 static int shmem_getattr(struct user_namespace *mnt_userns,
1049 const struct path *path, struct kstat *stat,
1050 u32 request_mask, unsigned int query_flags)
1052 struct inode *inode = path->dentry->d_inode;
1053 struct shmem_inode_info *info = SHMEM_I(inode);
1055 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
1056 spin_lock_irq(&info->lock);
1057 shmem_recalc_inode(inode);
1058 spin_unlock_irq(&info->lock);
1060 generic_fillattr(&init_user_ns, inode, stat);
1062 if (shmem_is_huge(NULL, inode, 0))
1063 stat->blksize = HPAGE_PMD_SIZE;
1065 if (request_mask & STATX_BTIME) {
1066 stat->result_mask |= STATX_BTIME;
1067 stat->btime.tv_sec = info->i_crtime.tv_sec;
1068 stat->btime.tv_nsec = info->i_crtime.tv_nsec;
1074 static int shmem_setattr(struct user_namespace *mnt_userns,
1075 struct dentry *dentry, struct iattr *attr)
1077 struct inode *inode = d_inode(dentry);
1078 struct shmem_inode_info *info = SHMEM_I(inode);
1081 error = setattr_prepare(&init_user_ns, dentry, attr);
1085 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1086 loff_t oldsize = inode->i_size;
1087 loff_t newsize = attr->ia_size;
1089 /* protected by i_rwsem */
1090 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1091 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1094 if (newsize != oldsize) {
1095 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1099 i_size_write(inode, newsize);
1100 inode->i_ctime = inode->i_mtime = current_time(inode);
1102 if (newsize <= oldsize) {
1103 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1104 if (oldsize > holebegin)
1105 unmap_mapping_range(inode->i_mapping,
1108 shmem_truncate_range(inode,
1109 newsize, (loff_t)-1);
1110 /* unmap again to remove racily COWed private pages */
1111 if (oldsize > holebegin)
1112 unmap_mapping_range(inode->i_mapping,
1117 setattr_copy(&init_user_ns, inode, attr);
1118 if (attr->ia_valid & ATTR_MODE)
1119 error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
1123 static void shmem_evict_inode(struct inode *inode)
1125 struct shmem_inode_info *info = SHMEM_I(inode);
1126 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1128 if (shmem_mapping(inode->i_mapping)) {
1129 shmem_unacct_size(info->flags, inode->i_size);
1131 mapping_set_exiting(inode->i_mapping);
1132 shmem_truncate_range(inode, 0, (loff_t)-1);
1133 if (!list_empty(&info->shrinklist)) {
1134 spin_lock(&sbinfo->shrinklist_lock);
1135 if (!list_empty(&info->shrinklist)) {
1136 list_del_init(&info->shrinklist);
1137 sbinfo->shrinklist_len--;
1139 spin_unlock(&sbinfo->shrinklist_lock);
1141 while (!list_empty(&info->swaplist)) {
1142 /* Wait while shmem_unuse() is scanning this inode... */
1143 wait_var_event(&info->stop_eviction,
1144 !atomic_read(&info->stop_eviction));
1145 mutex_lock(&shmem_swaplist_mutex);
1146 /* ...but beware of the race if we peeked too early */
1147 if (!atomic_read(&info->stop_eviction))
1148 list_del_init(&info->swaplist);
1149 mutex_unlock(&shmem_swaplist_mutex);
1153 simple_xattrs_free(&info->xattrs);
1154 WARN_ON(inode->i_blocks);
1155 shmem_free_inode(inode->i_sb);
1159 static int shmem_find_swap_entries(struct address_space *mapping,
1160 pgoff_t start, struct folio_batch *fbatch,
1161 pgoff_t *indices, unsigned int type)
1163 XA_STATE(xas, &mapping->i_pages, start);
1164 struct folio *folio;
1168 xas_for_each(&xas, folio, ULONG_MAX) {
1169 if (xas_retry(&xas, folio))
1172 if (!xa_is_value(folio))
1175 entry = radix_to_swp_entry(folio);
1177 * swapin error entries can be found in the mapping. But they're
1178 * deliberately ignored here as we've done everything we can do.
1180 if (swp_type(entry) != type)
1183 indices[folio_batch_count(fbatch)] = xas.xa_index;
1184 if (!folio_batch_add(fbatch, folio))
1187 if (need_resched()) {
1194 return xas.xa_index;
1198 * Move the swapped pages for an inode to page cache. Returns the count
1199 * of pages swapped in, or the error in case of failure.
1201 static int shmem_unuse_swap_entries(struct inode *inode,
1202 struct folio_batch *fbatch, pgoff_t *indices)
1207 struct address_space *mapping = inode->i_mapping;
1209 for (i = 0; i < folio_batch_count(fbatch); i++) {
1210 struct folio *folio = fbatch->folios[i];
1212 if (!xa_is_value(folio))
1214 error = shmem_swapin_folio(inode, indices[i],
1216 mapping_gfp_mask(mapping),
1219 folio_unlock(folio);
1223 if (error == -ENOMEM)
1227 return error ? error : ret;
1231 * If swap found in inode, free it and move page from swapcache to filecache.
1233 static int shmem_unuse_inode(struct inode *inode, unsigned int type)
1235 struct address_space *mapping = inode->i_mapping;
1237 struct folio_batch fbatch;
1238 pgoff_t indices[PAGEVEC_SIZE];
1242 folio_batch_init(&fbatch);
1243 shmem_find_swap_entries(mapping, start, &fbatch, indices, type);
1244 if (folio_batch_count(&fbatch) == 0) {
1249 ret = shmem_unuse_swap_entries(inode, &fbatch, indices);
1253 start = indices[folio_batch_count(&fbatch) - 1];
1260 * Read all the shared memory data that resides in the swap
1261 * device 'type' back into memory, so the swap device can be
1264 int shmem_unuse(unsigned int type)
1266 struct shmem_inode_info *info, *next;
1269 if (list_empty(&shmem_swaplist))
1272 mutex_lock(&shmem_swaplist_mutex);
1273 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1274 if (!info->swapped) {
1275 list_del_init(&info->swaplist);
1279 * Drop the swaplist mutex while searching the inode for swap;
1280 * but before doing so, make sure shmem_evict_inode() will not
1281 * remove placeholder inode from swaplist, nor let it be freed
1282 * (igrab() would protect from unlink, but not from unmount).
1284 atomic_inc(&info->stop_eviction);
1285 mutex_unlock(&shmem_swaplist_mutex);
1287 error = shmem_unuse_inode(&info->vfs_inode, type);
1290 mutex_lock(&shmem_swaplist_mutex);
1291 next = list_next_entry(info, swaplist);
1293 list_del_init(&info->swaplist);
1294 if (atomic_dec_and_test(&info->stop_eviction))
1295 wake_up_var(&info->stop_eviction);
1299 mutex_unlock(&shmem_swaplist_mutex);
1305 * Move the page from the page cache to the swap cache.
1307 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1309 struct folio *folio = page_folio(page);
1310 struct shmem_inode_info *info;
1311 struct address_space *mapping;
1312 struct inode *inode;
1317 * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or
1318 * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
1319 * and its shmem_writeback() needs them to be split when swapping.
1321 if (PageTransCompound(page)) {
1322 /* Ensure the subpages are still dirty */
1324 if (split_huge_page(page) < 0)
1326 ClearPageDirty(page);
1329 BUG_ON(!PageLocked(page));
1330 mapping = page->mapping;
1331 index = page->index;
1332 inode = mapping->host;
1333 info = SHMEM_I(inode);
1334 if (info->flags & VM_LOCKED)
1336 if (!total_swap_pages)
1340 * Our capabilities prevent regular writeback or sync from ever calling
1341 * shmem_writepage; but a stacking filesystem might use ->writepage of
1342 * its underlying filesystem, in which case tmpfs should write out to
1343 * swap only in response to memory pressure, and not for the writeback
1346 if (!wbc->for_reclaim) {
1347 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1352 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1353 * value into swapfile.c, the only way we can correctly account for a
1354 * fallocated page arriving here is now to initialize it and write it.
1356 * That's okay for a page already fallocated earlier, but if we have
1357 * not yet completed the fallocation, then (a) we want to keep track
1358 * of this page in case we have to undo it, and (b) it may not be a
1359 * good idea to continue anyway, once we're pushing into swap. So
1360 * reactivate the page, and let shmem_fallocate() quit when too many.
1362 if (!PageUptodate(page)) {
1363 if (inode->i_private) {
1364 struct shmem_falloc *shmem_falloc;
1365 spin_lock(&inode->i_lock);
1366 shmem_falloc = inode->i_private;
1368 !shmem_falloc->waitq &&
1369 index >= shmem_falloc->start &&
1370 index < shmem_falloc->next)
1371 shmem_falloc->nr_unswapped++;
1373 shmem_falloc = NULL;
1374 spin_unlock(&inode->i_lock);
1378 clear_highpage(page);
1379 flush_dcache_page(page);
1380 SetPageUptodate(page);
1383 swap = folio_alloc_swap(folio);
1388 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1389 * if it's not already there. Do it now before the page is
1390 * moved to swap cache, when its pagelock no longer protects
1391 * the inode from eviction. But don't unlock the mutex until
1392 * we've incremented swapped, because shmem_unuse_inode() will
1393 * prune a !swapped inode from the swaplist under this mutex.
1395 mutex_lock(&shmem_swaplist_mutex);
1396 if (list_empty(&info->swaplist))
1397 list_add(&info->swaplist, &shmem_swaplist);
1399 if (add_to_swap_cache(page, swap,
1400 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1402 spin_lock_irq(&info->lock);
1403 shmem_recalc_inode(inode);
1405 spin_unlock_irq(&info->lock);
1407 swap_shmem_alloc(swap);
1408 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1410 mutex_unlock(&shmem_swaplist_mutex);
1411 BUG_ON(page_mapped(page));
1412 swap_writepage(page, wbc);
1416 mutex_unlock(&shmem_swaplist_mutex);
1417 put_swap_page(page, swap);
1419 set_page_dirty(page);
1420 if (wbc->for_reclaim)
1421 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1426 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1427 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1431 if (!mpol || mpol->mode == MPOL_DEFAULT)
1432 return; /* show nothing */
1434 mpol_to_str(buffer, sizeof(buffer), mpol);
1436 seq_printf(seq, ",mpol=%s", buffer);
1439 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1441 struct mempolicy *mpol = NULL;
1443 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1444 mpol = sbinfo->mpol;
1446 raw_spin_unlock(&sbinfo->stat_lock);
1450 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1451 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1454 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1458 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1460 #define vm_policy vm_private_data
1463 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1464 struct shmem_inode_info *info, pgoff_t index)
1466 /* Create a pseudo vma that just contains the policy */
1467 vma_init(vma, NULL);
1468 /* Bias interleave by inode number to distribute better across nodes */
1469 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1470 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1473 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1475 /* Drop reference taken by mpol_shared_policy_lookup() */
1476 mpol_cond_put(vma->vm_policy);
1479 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1480 struct shmem_inode_info *info, pgoff_t index)
1482 struct vm_area_struct pvma;
1484 struct vm_fault vmf = {
1488 shmem_pseudo_vma_init(&pvma, info, index);
1489 page = swap_cluster_readahead(swap, gfp, &vmf);
1490 shmem_pseudo_vma_destroy(&pvma);
1496 * Make sure huge_gfp is always more limited than limit_gfp.
1497 * Some of the flags set permissions, while others set limitations.
1499 static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1501 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1502 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1503 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1504 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1506 /* Allow allocations only from the originally specified zones. */
1507 result |= zoneflags;
1510 * Minimize the result gfp by taking the union with the deny flags,
1511 * and the intersection of the allow flags.
1513 result |= (limit_gfp & denyflags);
1514 result |= (huge_gfp & limit_gfp) & allowflags;
1519 static struct folio *shmem_alloc_hugefolio(gfp_t gfp,
1520 struct shmem_inode_info *info, pgoff_t index)
1522 struct vm_area_struct pvma;
1523 struct address_space *mapping = info->vfs_inode.i_mapping;
1525 struct folio *folio;
1527 hindex = round_down(index, HPAGE_PMD_NR);
1528 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1532 shmem_pseudo_vma_init(&pvma, info, hindex);
1533 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, &pvma, 0, true);
1534 shmem_pseudo_vma_destroy(&pvma);
1536 count_vm_event(THP_FILE_FALLBACK);
1540 static struct folio *shmem_alloc_folio(gfp_t gfp,
1541 struct shmem_inode_info *info, pgoff_t index)
1543 struct vm_area_struct pvma;
1544 struct folio *folio;
1546 shmem_pseudo_vma_init(&pvma, info, index);
1547 folio = vma_alloc_folio(gfp, 0, &pvma, 0, false);
1548 shmem_pseudo_vma_destroy(&pvma);
1553 static struct page *shmem_alloc_page(gfp_t gfp,
1554 struct shmem_inode_info *info, pgoff_t index)
1556 return &shmem_alloc_folio(gfp, info, index)->page;
1559 static struct folio *shmem_alloc_and_acct_folio(gfp_t gfp, struct inode *inode,
1560 pgoff_t index, bool huge)
1562 struct shmem_inode_info *info = SHMEM_I(inode);
1563 struct folio *folio;
1567 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1569 nr = huge ? HPAGE_PMD_NR : 1;
1571 if (!shmem_inode_acct_block(inode, nr))
1575 folio = shmem_alloc_hugefolio(gfp, info, index);
1577 folio = shmem_alloc_folio(gfp, info, index);
1579 __folio_set_locked(folio);
1580 __folio_set_swapbacked(folio);
1585 shmem_inode_unacct_blocks(inode, nr);
1587 return ERR_PTR(err);
1591 * When a page is moved from swapcache to shmem filecache (either by the
1592 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1593 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1594 * ignorance of the mapping it belongs to. If that mapping has special
1595 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1596 * we may need to copy to a suitable page before moving to filecache.
1598 * In a future release, this may well be extended to respect cpuset and
1599 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1600 * but for now it is a simple matter of zone.
1602 static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
1604 return folio_zonenum(folio) > gfp_zone(gfp);
1607 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1608 struct shmem_inode_info *info, pgoff_t index)
1610 struct page *oldpage, *newpage;
1611 struct folio *old, *new;
1612 struct address_space *swap_mapping;
1618 entry.val = page_private(oldpage);
1619 swap_index = swp_offset(entry);
1620 swap_mapping = page_mapping(oldpage);
1623 * We have arrived here because our zones are constrained, so don't
1624 * limit chance of success by further cpuset and node constraints.
1626 gfp &= ~GFP_CONSTRAINT_MASK;
1627 newpage = shmem_alloc_page(gfp, info, index);
1632 copy_highpage(newpage, oldpage);
1633 flush_dcache_page(newpage);
1635 __SetPageLocked(newpage);
1636 __SetPageSwapBacked(newpage);
1637 SetPageUptodate(newpage);
1638 set_page_private(newpage, entry.val);
1639 SetPageSwapCache(newpage);
1642 * Our caller will very soon move newpage out of swapcache, but it's
1643 * a nice clean interface for us to replace oldpage by newpage there.
1645 xa_lock_irq(&swap_mapping->i_pages);
1646 error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
1648 old = page_folio(oldpage);
1649 new = page_folio(newpage);
1650 mem_cgroup_migrate(old, new);
1651 __inc_lruvec_page_state(newpage, NR_FILE_PAGES);
1652 __dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
1654 xa_unlock_irq(&swap_mapping->i_pages);
1656 if (unlikely(error)) {
1658 * Is this possible? I think not, now that our callers check
1659 * both PageSwapCache and page_private after getting page lock;
1660 * but be defensive. Reverse old to newpage for clear and free.
1664 lru_cache_add(newpage);
1668 ClearPageSwapCache(oldpage);
1669 set_page_private(oldpage, 0);
1671 unlock_page(oldpage);
1677 static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
1678 struct folio *folio, swp_entry_t swap)
1680 struct address_space *mapping = inode->i_mapping;
1681 struct shmem_inode_info *info = SHMEM_I(inode);
1682 swp_entry_t swapin_error;
1685 swapin_error = make_swapin_error_entry(&folio->page);
1686 old = xa_cmpxchg_irq(&mapping->i_pages, index,
1687 swp_to_radix_entry(swap),
1688 swp_to_radix_entry(swapin_error), 0);
1689 if (old != swp_to_radix_entry(swap))
1692 folio_wait_writeback(folio);
1693 delete_from_swap_cache(&folio->page);
1694 spin_lock_irq(&info->lock);
1696 * Don't treat swapin error folio as alloced. Otherwise inode->i_blocks won't
1697 * be 0 when inode is released and thus trigger WARN_ON(inode->i_blocks) in
1698 * shmem_evict_inode.
1702 shmem_recalc_inode(inode);
1703 spin_unlock_irq(&info->lock);
1708 * Swap in the page pointed to by *pagep.
1709 * Caller has to make sure that *pagep contains a valid swapped page.
1710 * Returns 0 and the page in pagep if success. On failure, returns the
1711 * error code and NULL in *pagep.
1713 static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
1714 struct folio **foliop, enum sgp_type sgp,
1715 gfp_t gfp, struct vm_area_struct *vma,
1716 vm_fault_t *fault_type)
1718 struct address_space *mapping = inode->i_mapping;
1719 struct shmem_inode_info *info = SHMEM_I(inode);
1720 struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
1722 struct folio *folio = NULL;
1726 VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
1727 swap = radix_to_swp_entry(*foliop);
1730 if (is_swapin_error_entry(swap))
1733 /* Look it up and read it in.. */
1734 page = lookup_swap_cache(swap, NULL, 0);
1736 /* Or update major stats only when swapin succeeds?? */
1738 *fault_type |= VM_FAULT_MAJOR;
1739 count_vm_event(PGMAJFAULT);
1740 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1742 /* Here we actually start the io */
1743 page = shmem_swapin(swap, gfp, info, index);
1749 folio = page_folio(page);
1751 /* We have to do this with page locked to prevent races */
1753 if (!folio_test_swapcache(folio) ||
1754 folio_swap_entry(folio).val != swap.val ||
1755 !shmem_confirm_swap(mapping, index, swap)) {
1759 if (!folio_test_uptodate(folio)) {
1763 folio_wait_writeback(folio);
1766 * Some architectures may have to restore extra metadata to the
1767 * folio after reading from swap.
1769 arch_swap_restore(swap, folio);
1771 if (shmem_should_replace_folio(folio, gfp)) {
1772 error = shmem_replace_page(&page, gfp, info, index);
1777 error = shmem_add_to_page_cache(folio, mapping, index,
1778 swp_to_radix_entry(swap), gfp,
1783 spin_lock_irq(&info->lock);
1785 shmem_recalc_inode(inode);
1786 spin_unlock_irq(&info->lock);
1788 if (sgp == SGP_WRITE)
1789 folio_mark_accessed(folio);
1791 delete_from_swap_cache(&folio->page);
1792 folio_mark_dirty(folio);
1798 if (!shmem_confirm_swap(mapping, index, swap))
1801 shmem_set_folio_swapin_error(inode, index, folio, swap);
1804 folio_unlock(folio);
1812 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1814 * If we allocate a new one we do not mark it dirty. That's up to the
1815 * vm. If we swap it in we mark it dirty since we also free the swap
1816 * entry since a page cannot live in both the swap and page cache.
1818 * vma, vmf, and fault_type are only supplied by shmem_fault:
1819 * otherwise they are NULL.
1821 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1822 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1823 struct vm_area_struct *vma, struct vm_fault *vmf,
1824 vm_fault_t *fault_type)
1826 struct address_space *mapping = inode->i_mapping;
1827 struct shmem_inode_info *info = SHMEM_I(inode);
1828 struct shmem_sb_info *sbinfo;
1829 struct mm_struct *charge_mm;
1830 struct folio *folio;
1831 pgoff_t hindex = index;
1837 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1840 if (sgp <= SGP_CACHE &&
1841 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1845 sbinfo = SHMEM_SB(inode->i_sb);
1846 charge_mm = vma ? vma->vm_mm : NULL;
1848 folio = __filemap_get_folio(mapping, index, FGP_ENTRY | FGP_LOCK, 0);
1849 if (folio && vma && userfaultfd_minor(vma)) {
1850 if (!xa_is_value(folio)) {
1851 folio_unlock(folio);
1854 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
1858 if (xa_is_value(folio)) {
1859 error = shmem_swapin_folio(inode, index, &folio,
1860 sgp, gfp, vma, fault_type);
1861 if (error == -EEXIST)
1864 *pagep = &folio->page;
1869 hindex = folio->index;
1870 if (sgp == SGP_WRITE)
1871 folio_mark_accessed(folio);
1872 if (folio_test_uptodate(folio))
1874 /* fallocated page */
1875 if (sgp != SGP_READ)
1877 folio_unlock(folio);
1882 * SGP_READ: succeed on hole, with NULL page, letting caller zero.
1883 * SGP_NOALLOC: fail on hole, with NULL page, letting caller fail.
1886 if (sgp == SGP_READ)
1888 if (sgp == SGP_NOALLOC)
1892 * Fast cache lookup and swap lookup did not find it: allocate.
1895 if (vma && userfaultfd_missing(vma)) {
1896 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1900 if (!shmem_is_huge(vma, inode, index))
1903 huge_gfp = vma_thp_gfp_mask(vma);
1904 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
1905 folio = shmem_alloc_and_acct_folio(huge_gfp, inode, index, true);
1906 if (IS_ERR(folio)) {
1908 folio = shmem_alloc_and_acct_folio(gfp, inode, index, false);
1910 if (IS_ERR(folio)) {
1913 error = PTR_ERR(folio);
1915 if (error != -ENOSPC)
1918 * Try to reclaim some space by splitting a huge page
1919 * beyond i_size on the filesystem.
1924 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1925 if (ret == SHRINK_STOP)
1933 hindex = round_down(index, folio_nr_pages(folio));
1935 if (sgp == SGP_WRITE)
1936 __folio_set_referenced(folio);
1938 error = shmem_add_to_page_cache(folio, mapping, hindex,
1939 NULL, gfp & GFP_RECLAIM_MASK,
1943 folio_add_lru(folio);
1945 spin_lock_irq(&info->lock);
1946 info->alloced += folio_nr_pages(folio);
1947 inode->i_blocks += (blkcnt_t)BLOCKS_PER_PAGE << folio_order(folio);
1948 shmem_recalc_inode(inode);
1949 spin_unlock_irq(&info->lock);
1952 if (folio_test_pmd_mappable(folio) &&
1953 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1954 hindex + HPAGE_PMD_NR - 1) {
1956 * Part of the huge page is beyond i_size: subject
1957 * to shrink under memory pressure.
1959 spin_lock(&sbinfo->shrinklist_lock);
1961 * _careful to defend against unlocked access to
1962 * ->shrink_list in shmem_unused_huge_shrink()
1964 if (list_empty_careful(&info->shrinklist)) {
1965 list_add_tail(&info->shrinklist,
1966 &sbinfo->shrinklist);
1967 sbinfo->shrinklist_len++;
1969 spin_unlock(&sbinfo->shrinklist_lock);
1973 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1975 if (sgp == SGP_FALLOC)
1979 * Let SGP_WRITE caller clear ends if write does not fill page;
1980 * but SGP_FALLOC on a page fallocated earlier must initialize
1981 * it now, lest undo on failure cancel our earlier guarantee.
1983 if (sgp != SGP_WRITE && !folio_test_uptodate(folio)) {
1984 long i, n = folio_nr_pages(folio);
1986 for (i = 0; i < n; i++)
1987 clear_highpage(folio_page(folio, i));
1988 flush_dcache_folio(folio);
1989 folio_mark_uptodate(folio);
1992 /* Perhaps the file has been truncated since we checked */
1993 if (sgp <= SGP_CACHE &&
1994 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1996 folio_clear_dirty(folio);
1997 filemap_remove_folio(folio);
1998 spin_lock_irq(&info->lock);
1999 shmem_recalc_inode(inode);
2000 spin_unlock_irq(&info->lock);
2006 *pagep = folio_page(folio, index - hindex);
2013 shmem_inode_unacct_blocks(inode, folio_nr_pages(folio));
2015 if (folio_test_large(folio)) {
2016 folio_unlock(folio);
2022 folio_unlock(folio);
2025 if (error == -ENOSPC && !once++) {
2026 spin_lock_irq(&info->lock);
2027 shmem_recalc_inode(inode);
2028 spin_unlock_irq(&info->lock);
2031 if (error == -EEXIST)
2037 * This is like autoremove_wake_function, but it removes the wait queue
2038 * entry unconditionally - even if something else had already woken the
2041 static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
2043 int ret = default_wake_function(wait, mode, sync, key);
2044 list_del_init(&wait->entry);
2048 static vm_fault_t shmem_fault(struct vm_fault *vmf)
2050 struct vm_area_struct *vma = vmf->vma;
2051 struct inode *inode = file_inode(vma->vm_file);
2052 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2054 vm_fault_t ret = VM_FAULT_LOCKED;
2057 * Trinity finds that probing a hole which tmpfs is punching can
2058 * prevent the hole-punch from ever completing: which in turn
2059 * locks writers out with its hold on i_rwsem. So refrain from
2060 * faulting pages into the hole while it's being punched. Although
2061 * shmem_undo_range() does remove the additions, it may be unable to
2062 * keep up, as each new page needs its own unmap_mapping_range() call,
2063 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2065 * It does not matter if we sometimes reach this check just before the
2066 * hole-punch begins, so that one fault then races with the punch:
2067 * we just need to make racing faults a rare case.
2069 * The implementation below would be much simpler if we just used a
2070 * standard mutex or completion: but we cannot take i_rwsem in fault,
2071 * and bloating every shmem inode for this unlikely case would be sad.
2073 if (unlikely(inode->i_private)) {
2074 struct shmem_falloc *shmem_falloc;
2076 spin_lock(&inode->i_lock);
2077 shmem_falloc = inode->i_private;
2079 shmem_falloc->waitq &&
2080 vmf->pgoff >= shmem_falloc->start &&
2081 vmf->pgoff < shmem_falloc->next) {
2083 wait_queue_head_t *shmem_falloc_waitq;
2084 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2086 ret = VM_FAULT_NOPAGE;
2087 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2089 ret = VM_FAULT_RETRY;
2091 shmem_falloc_waitq = shmem_falloc->waitq;
2092 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2093 TASK_UNINTERRUPTIBLE);
2094 spin_unlock(&inode->i_lock);
2098 * shmem_falloc_waitq points into the shmem_fallocate()
2099 * stack of the hole-punching task: shmem_falloc_waitq
2100 * is usually invalid by the time we reach here, but
2101 * finish_wait() does not dereference it in that case;
2102 * though i_lock needed lest racing with wake_up_all().
2104 spin_lock(&inode->i_lock);
2105 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2106 spin_unlock(&inode->i_lock);
2112 spin_unlock(&inode->i_lock);
2115 err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE,
2116 gfp, vma, vmf, &ret);
2118 return vmf_error(err);
2122 unsigned long shmem_get_unmapped_area(struct file *file,
2123 unsigned long uaddr, unsigned long len,
2124 unsigned long pgoff, unsigned long flags)
2126 unsigned long (*get_area)(struct file *,
2127 unsigned long, unsigned long, unsigned long, unsigned long);
2129 unsigned long offset;
2130 unsigned long inflated_len;
2131 unsigned long inflated_addr;
2132 unsigned long inflated_offset;
2134 if (len > TASK_SIZE)
2137 get_area = current->mm->get_unmapped_area;
2138 addr = get_area(file, uaddr, len, pgoff, flags);
2140 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2142 if (IS_ERR_VALUE(addr))
2144 if (addr & ~PAGE_MASK)
2146 if (addr > TASK_SIZE - len)
2149 if (shmem_huge == SHMEM_HUGE_DENY)
2151 if (len < HPAGE_PMD_SIZE)
2153 if (flags & MAP_FIXED)
2156 * Our priority is to support MAP_SHARED mapped hugely;
2157 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2158 * But if caller specified an address hint and we allocated area there
2159 * successfully, respect that as before.
2164 if (shmem_huge != SHMEM_HUGE_FORCE) {
2165 struct super_block *sb;
2168 VM_BUG_ON(file->f_op != &shmem_file_operations);
2169 sb = file_inode(file)->i_sb;
2172 * Called directly from mm/mmap.c, or drivers/char/mem.c
2173 * for "/dev/zero", to create a shared anonymous object.
2175 if (IS_ERR(shm_mnt))
2177 sb = shm_mnt->mnt_sb;
2179 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2183 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2184 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2186 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2189 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2190 if (inflated_len > TASK_SIZE)
2192 if (inflated_len < len)
2195 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2196 if (IS_ERR_VALUE(inflated_addr))
2198 if (inflated_addr & ~PAGE_MASK)
2201 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2202 inflated_addr += offset - inflated_offset;
2203 if (inflated_offset > offset)
2204 inflated_addr += HPAGE_PMD_SIZE;
2206 if (inflated_addr > TASK_SIZE - len)
2208 return inflated_addr;
2212 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2214 struct inode *inode = file_inode(vma->vm_file);
2215 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2218 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2221 struct inode *inode = file_inode(vma->vm_file);
2224 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2225 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2229 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2231 struct inode *inode = file_inode(file);
2232 struct shmem_inode_info *info = SHMEM_I(inode);
2233 int retval = -ENOMEM;
2236 * What serializes the accesses to info->flags?
2237 * ipc_lock_object() when called from shmctl_do_lock(),
2238 * no serialization needed when called from shm_destroy().
2240 if (lock && !(info->flags & VM_LOCKED)) {
2241 if (!user_shm_lock(inode->i_size, ucounts))
2243 info->flags |= VM_LOCKED;
2244 mapping_set_unevictable(file->f_mapping);
2246 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2247 user_shm_unlock(inode->i_size, ucounts);
2248 info->flags &= ~VM_LOCKED;
2249 mapping_clear_unevictable(file->f_mapping);
2257 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2259 struct shmem_inode_info *info = SHMEM_I(file_inode(file));
2262 ret = seal_check_future_write(info->seals, vma);
2266 /* arm64 - allow memory tagging on RAM-based files */
2267 vma->vm_flags |= VM_MTE_ALLOWED;
2269 file_accessed(file);
2270 vma->vm_ops = &shmem_vm_ops;
2274 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2275 umode_t mode, dev_t dev, unsigned long flags)
2277 struct inode *inode;
2278 struct shmem_inode_info *info;
2279 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2282 if (shmem_reserve_inode(sb, &ino))
2285 inode = new_inode(sb);
2288 inode_init_owner(&init_user_ns, inode, dir, mode);
2289 inode->i_blocks = 0;
2290 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2291 inode->i_generation = prandom_u32();
2292 info = SHMEM_I(inode);
2293 memset(info, 0, (char *)inode - (char *)info);
2294 spin_lock_init(&info->lock);
2295 atomic_set(&info->stop_eviction, 0);
2296 info->seals = F_SEAL_SEAL;
2297 info->flags = flags & VM_NORESERVE;
2298 info->i_crtime = inode->i_mtime;
2299 INIT_LIST_HEAD(&info->shrinklist);
2300 INIT_LIST_HEAD(&info->swaplist);
2301 simple_xattrs_init(&info->xattrs);
2302 cache_no_acl(inode);
2303 mapping_set_large_folios(inode->i_mapping);
2305 switch (mode & S_IFMT) {
2307 inode->i_op = &shmem_special_inode_operations;
2308 init_special_inode(inode, mode, dev);
2311 inode->i_mapping->a_ops = &shmem_aops;
2312 inode->i_op = &shmem_inode_operations;
2313 inode->i_fop = &shmem_file_operations;
2314 mpol_shared_policy_init(&info->policy,
2315 shmem_get_sbmpol(sbinfo));
2319 /* Some things misbehave if size == 0 on a directory */
2320 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2321 inode->i_op = &shmem_dir_inode_operations;
2322 inode->i_fop = &simple_dir_operations;
2326 * Must not load anything in the rbtree,
2327 * mpol_free_shared_policy will not be called.
2329 mpol_shared_policy_init(&info->policy, NULL);
2333 lockdep_annotate_inode_mutex_key(inode);
2335 shmem_free_inode(sb);
2339 #ifdef CONFIG_USERFAULTFD
2340 int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2342 struct vm_area_struct *dst_vma,
2343 unsigned long dst_addr,
2344 unsigned long src_addr,
2345 bool zeropage, bool wp_copy,
2346 struct page **pagep)
2348 struct inode *inode = file_inode(dst_vma->vm_file);
2349 struct shmem_inode_info *info = SHMEM_I(inode);
2350 struct address_space *mapping = inode->i_mapping;
2351 gfp_t gfp = mapping_gfp_mask(mapping);
2352 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2354 struct folio *folio;
2359 if (!shmem_inode_acct_block(inode, 1)) {
2361 * We may have got a page, returned -ENOENT triggering a retry,
2362 * and now we find ourselves with -ENOMEM. Release the page, to
2363 * avoid a BUG_ON in our caller.
2365 if (unlikely(*pagep)) {
2374 page = shmem_alloc_page(gfp, info, pgoff);
2376 goto out_unacct_blocks;
2378 if (!zeropage) { /* COPY */
2379 page_kaddr = kmap_atomic(page);
2380 ret = copy_from_user(page_kaddr,
2381 (const void __user *)src_addr,
2383 kunmap_atomic(page_kaddr);
2385 /* fallback to copy_from_user outside mmap_lock */
2386 if (unlikely(ret)) {
2389 /* don't free the page */
2390 goto out_unacct_blocks;
2393 flush_dcache_page(page);
2394 } else { /* ZEROPAGE */
2395 clear_user_highpage(page, dst_addr);
2402 VM_BUG_ON(PageLocked(page));
2403 VM_BUG_ON(PageSwapBacked(page));
2404 __SetPageLocked(page);
2405 __SetPageSwapBacked(page);
2406 __SetPageUptodate(page);
2409 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2410 if (unlikely(pgoff >= max_off))
2413 folio = page_folio(page);
2414 ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL,
2415 gfp & GFP_RECLAIM_MASK, dst_mm);
2419 ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
2420 page, true, wp_copy);
2422 goto out_delete_from_cache;
2424 spin_lock_irq(&info->lock);
2426 inode->i_blocks += BLOCKS_PER_PAGE;
2427 shmem_recalc_inode(inode);
2428 spin_unlock_irq(&info->lock);
2432 out_delete_from_cache:
2433 delete_from_page_cache(page);
2438 shmem_inode_unacct_blocks(inode, 1);
2441 #endif /* CONFIG_USERFAULTFD */
2444 static const struct inode_operations shmem_symlink_inode_operations;
2445 static const struct inode_operations shmem_short_symlink_operations;
2447 #ifdef CONFIG_TMPFS_XATTR
2448 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2450 #define shmem_initxattrs NULL
2454 shmem_write_begin(struct file *file, struct address_space *mapping,
2455 loff_t pos, unsigned len,
2456 struct page **pagep, void **fsdata)
2458 struct inode *inode = mapping->host;
2459 struct shmem_inode_info *info = SHMEM_I(inode);
2460 pgoff_t index = pos >> PAGE_SHIFT;
2463 /* i_rwsem is held by caller */
2464 if (unlikely(info->seals & (F_SEAL_GROW |
2465 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2466 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2468 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2472 ret = shmem_getpage(inode, index, pagep, SGP_WRITE);
2477 if (PageHWPoison(*pagep)) {
2478 unlock_page(*pagep);
2488 shmem_write_end(struct file *file, struct address_space *mapping,
2489 loff_t pos, unsigned len, unsigned copied,
2490 struct page *page, void *fsdata)
2492 struct inode *inode = mapping->host;
2494 if (pos + copied > inode->i_size)
2495 i_size_write(inode, pos + copied);
2497 if (!PageUptodate(page)) {
2498 struct page *head = compound_head(page);
2499 if (PageTransCompound(page)) {
2502 for (i = 0; i < HPAGE_PMD_NR; i++) {
2503 if (head + i == page)
2505 clear_highpage(head + i);
2506 flush_dcache_page(head + i);
2509 if (copied < PAGE_SIZE) {
2510 unsigned from = pos & (PAGE_SIZE - 1);
2511 zero_user_segments(page, 0, from,
2512 from + copied, PAGE_SIZE);
2514 SetPageUptodate(head);
2516 set_page_dirty(page);
2523 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2525 struct file *file = iocb->ki_filp;
2526 struct inode *inode = file_inode(file);
2527 struct address_space *mapping = inode->i_mapping;
2529 unsigned long offset;
2532 loff_t *ppos = &iocb->ki_pos;
2534 index = *ppos >> PAGE_SHIFT;
2535 offset = *ppos & ~PAGE_MASK;
2538 struct page *page = NULL;
2540 unsigned long nr, ret;
2541 loff_t i_size = i_size_read(inode);
2543 end_index = i_size >> PAGE_SHIFT;
2544 if (index > end_index)
2546 if (index == end_index) {
2547 nr = i_size & ~PAGE_MASK;
2552 error = shmem_getpage(inode, index, &page, SGP_READ);
2554 if (error == -EINVAL)
2561 if (PageHWPoison(page)) {
2569 * We must evaluate after, since reads (unlike writes)
2570 * are called without i_rwsem protection against truncate
2573 i_size = i_size_read(inode);
2574 end_index = i_size >> PAGE_SHIFT;
2575 if (index == end_index) {
2576 nr = i_size & ~PAGE_MASK;
2587 * If users can be writing to this page using arbitrary
2588 * virtual addresses, take care about potential aliasing
2589 * before reading the page on the kernel side.
2591 if (mapping_writably_mapped(mapping))
2592 flush_dcache_page(page);
2594 * Mark the page accessed if we read the beginning.
2597 mark_page_accessed(page);
2599 * Ok, we have the page, and it's up-to-date, so
2600 * now we can copy it to user space...
2602 ret = copy_page_to_iter(page, offset, nr, to);
2605 } else if (iter_is_iovec(to)) {
2607 * Copy to user tends to be so well optimized, but
2608 * clear_user() not so much, that it is noticeably
2609 * faster to copy the zero page instead of clearing.
2611 ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to);
2614 * But submitting the same page twice in a row to
2615 * splice() - or others? - can result in confusion:
2616 * so don't attempt that optimization on pipes etc.
2618 ret = iov_iter_zero(nr, to);
2623 index += offset >> PAGE_SHIFT;
2624 offset &= ~PAGE_MASK;
2626 if (!iov_iter_count(to))
2635 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2636 file_accessed(file);
2637 return retval ? retval : error;
2640 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2642 struct address_space *mapping = file->f_mapping;
2643 struct inode *inode = mapping->host;
2645 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2646 return generic_file_llseek_size(file, offset, whence,
2647 MAX_LFS_FILESIZE, i_size_read(inode));
2652 /* We're holding i_rwsem so we can access i_size directly */
2653 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
2655 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2656 inode_unlock(inode);
2660 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2663 struct inode *inode = file_inode(file);
2664 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2665 struct shmem_inode_info *info = SHMEM_I(inode);
2666 struct shmem_falloc shmem_falloc;
2667 pgoff_t start, index, end, undo_fallocend;
2670 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2675 if (mode & FALLOC_FL_PUNCH_HOLE) {
2676 struct address_space *mapping = file->f_mapping;
2677 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2678 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2679 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2681 /* protected by i_rwsem */
2682 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
2687 shmem_falloc.waitq = &shmem_falloc_waitq;
2688 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
2689 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2690 spin_lock(&inode->i_lock);
2691 inode->i_private = &shmem_falloc;
2692 spin_unlock(&inode->i_lock);
2694 if ((u64)unmap_end > (u64)unmap_start)
2695 unmap_mapping_range(mapping, unmap_start,
2696 1 + unmap_end - unmap_start, 0);
2697 shmem_truncate_range(inode, offset, offset + len - 1);
2698 /* No need to unmap again: hole-punching leaves COWed pages */
2700 spin_lock(&inode->i_lock);
2701 inode->i_private = NULL;
2702 wake_up_all(&shmem_falloc_waitq);
2703 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2704 spin_unlock(&inode->i_lock);
2709 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2710 error = inode_newsize_ok(inode, offset + len);
2714 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2719 start = offset >> PAGE_SHIFT;
2720 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2721 /* Try to avoid a swapstorm if len is impossible to satisfy */
2722 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2727 shmem_falloc.waitq = NULL;
2728 shmem_falloc.start = start;
2729 shmem_falloc.next = start;
2730 shmem_falloc.nr_falloced = 0;
2731 shmem_falloc.nr_unswapped = 0;
2732 spin_lock(&inode->i_lock);
2733 inode->i_private = &shmem_falloc;
2734 spin_unlock(&inode->i_lock);
2737 * info->fallocend is only relevant when huge pages might be
2738 * involved: to prevent split_huge_page() freeing fallocated
2739 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
2741 undo_fallocend = info->fallocend;
2742 if (info->fallocend < end)
2743 info->fallocend = end;
2745 for (index = start; index < end; ) {
2749 * Good, the fallocate(2) manpage permits EINTR: we may have
2750 * been interrupted because we are using up too much memory.
2752 if (signal_pending(current))
2754 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2757 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2759 info->fallocend = undo_fallocend;
2760 /* Remove the !PageUptodate pages we added */
2761 if (index > start) {
2762 shmem_undo_range(inode,
2763 (loff_t)start << PAGE_SHIFT,
2764 ((loff_t)index << PAGE_SHIFT) - 1, true);
2771 * Here is a more important optimization than it appears:
2772 * a second SGP_FALLOC on the same huge page will clear it,
2773 * making it PageUptodate and un-undoable if we fail later.
2775 if (PageTransCompound(page)) {
2776 index = round_up(index, HPAGE_PMD_NR);
2777 /* Beware 32-bit wraparound */
2783 * Inform shmem_writepage() how far we have reached.
2784 * No need for lock or barrier: we have the page lock.
2786 if (!PageUptodate(page))
2787 shmem_falloc.nr_falloced += index - shmem_falloc.next;
2788 shmem_falloc.next = index;
2791 * If !PageUptodate, leave it that way so that freeable pages
2792 * can be recognized if we need to rollback on error later.
2793 * But set_page_dirty so that memory pressure will swap rather
2794 * than free the pages we are allocating (and SGP_CACHE pages
2795 * might still be clean: we now need to mark those dirty too).
2797 set_page_dirty(page);
2803 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2804 i_size_write(inode, offset + len);
2805 inode->i_ctime = current_time(inode);
2807 spin_lock(&inode->i_lock);
2808 inode->i_private = NULL;
2809 spin_unlock(&inode->i_lock);
2811 inode_unlock(inode);
2815 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2817 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2819 buf->f_type = TMPFS_MAGIC;
2820 buf->f_bsize = PAGE_SIZE;
2821 buf->f_namelen = NAME_MAX;
2822 if (sbinfo->max_blocks) {
2823 buf->f_blocks = sbinfo->max_blocks;
2825 buf->f_bfree = sbinfo->max_blocks -
2826 percpu_counter_sum(&sbinfo->used_blocks);
2828 if (sbinfo->max_inodes) {
2829 buf->f_files = sbinfo->max_inodes;
2830 buf->f_ffree = sbinfo->free_inodes;
2832 /* else leave those fields 0 like simple_statfs */
2834 buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
2840 * File creation. Allocate an inode, and we're done..
2843 shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
2844 struct dentry *dentry, umode_t mode, dev_t dev)
2846 struct inode *inode;
2847 int error = -ENOSPC;
2849 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2851 error = simple_acl_create(dir, inode);
2854 error = security_inode_init_security(inode, dir,
2856 shmem_initxattrs, NULL);
2857 if (error && error != -EOPNOTSUPP)
2861 dir->i_size += BOGO_DIRENT_SIZE;
2862 dir->i_ctime = dir->i_mtime = current_time(dir);
2863 d_instantiate(dentry, inode);
2864 dget(dentry); /* Extra count - pin the dentry in core */
2873 shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
2874 struct dentry *dentry, umode_t mode)
2876 struct inode *inode;
2877 int error = -ENOSPC;
2879 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2881 error = security_inode_init_security(inode, dir,
2883 shmem_initxattrs, NULL);
2884 if (error && error != -EOPNOTSUPP)
2886 error = simple_acl_create(dir, inode);
2889 d_tmpfile(dentry, inode);
2897 static int shmem_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
2898 struct dentry *dentry, umode_t mode)
2902 if ((error = shmem_mknod(&init_user_ns, dir, dentry,
2903 mode | S_IFDIR, 0)))
2909 static int shmem_create(struct user_namespace *mnt_userns, struct inode *dir,
2910 struct dentry *dentry, umode_t mode, bool excl)
2912 return shmem_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0);
2918 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2920 struct inode *inode = d_inode(old_dentry);
2924 * No ordinary (disk based) filesystem counts links as inodes;
2925 * but each new link needs a new dentry, pinning lowmem, and
2926 * tmpfs dentries cannot be pruned until they are unlinked.
2927 * But if an O_TMPFILE file is linked into the tmpfs, the
2928 * first link must skip that, to get the accounting right.
2930 if (inode->i_nlink) {
2931 ret = shmem_reserve_inode(inode->i_sb, NULL);
2936 dir->i_size += BOGO_DIRENT_SIZE;
2937 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2939 ihold(inode); /* New dentry reference */
2940 dget(dentry); /* Extra pinning count for the created dentry */
2941 d_instantiate(dentry, inode);
2946 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2948 struct inode *inode = d_inode(dentry);
2950 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2951 shmem_free_inode(inode->i_sb);
2953 dir->i_size -= BOGO_DIRENT_SIZE;
2954 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2956 dput(dentry); /* Undo the count from "create" - this does all the work */
2960 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2962 if (!simple_empty(dentry))
2965 drop_nlink(d_inode(dentry));
2967 return shmem_unlink(dir, dentry);
2970 static int shmem_whiteout(struct user_namespace *mnt_userns,
2971 struct inode *old_dir, struct dentry *old_dentry)
2973 struct dentry *whiteout;
2976 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
2980 error = shmem_mknod(&init_user_ns, old_dir, whiteout,
2981 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
2987 * Cheat and hash the whiteout while the old dentry is still in
2988 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
2990 * d_lookup() will consistently find one of them at this point,
2991 * not sure which one, but that isn't even important.
2998 * The VFS layer already does all the dentry stuff for rename,
2999 * we just have to decrement the usage count for the target if
3000 * it exists so that the VFS layer correctly free's it when it
3003 static int shmem_rename2(struct user_namespace *mnt_userns,
3004 struct inode *old_dir, struct dentry *old_dentry,
3005 struct inode *new_dir, struct dentry *new_dentry,
3008 struct inode *inode = d_inode(old_dentry);
3009 int they_are_dirs = S_ISDIR(inode->i_mode);
3011 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3014 if (flags & RENAME_EXCHANGE)
3015 return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
3017 if (!simple_empty(new_dentry))
3020 if (flags & RENAME_WHITEOUT) {
3023 error = shmem_whiteout(&init_user_ns, old_dir, old_dentry);
3028 if (d_really_is_positive(new_dentry)) {
3029 (void) shmem_unlink(new_dir, new_dentry);
3030 if (they_are_dirs) {
3031 drop_nlink(d_inode(new_dentry));
3032 drop_nlink(old_dir);
3034 } else if (they_are_dirs) {
3035 drop_nlink(old_dir);
3039 old_dir->i_size -= BOGO_DIRENT_SIZE;
3040 new_dir->i_size += BOGO_DIRENT_SIZE;
3041 old_dir->i_ctime = old_dir->i_mtime =
3042 new_dir->i_ctime = new_dir->i_mtime =
3043 inode->i_ctime = current_time(old_dir);
3047 static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir,
3048 struct dentry *dentry, const char *symname)
3052 struct inode *inode;
3055 len = strlen(symname) + 1;
3056 if (len > PAGE_SIZE)
3057 return -ENAMETOOLONG;
3059 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0,
3064 error = security_inode_init_security(inode, dir, &dentry->d_name,
3065 shmem_initxattrs, NULL);
3066 if (error && error != -EOPNOTSUPP) {
3071 inode->i_size = len-1;
3072 if (len <= SHORT_SYMLINK_LEN) {
3073 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3074 if (!inode->i_link) {
3078 inode->i_op = &shmem_short_symlink_operations;
3080 inode_nohighmem(inode);
3081 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3086 inode->i_mapping->a_ops = &shmem_aops;
3087 inode->i_op = &shmem_symlink_inode_operations;
3088 memcpy(page_address(page), symname, len);
3089 SetPageUptodate(page);
3090 set_page_dirty(page);
3094 dir->i_size += BOGO_DIRENT_SIZE;
3095 dir->i_ctime = dir->i_mtime = current_time(dir);
3096 d_instantiate(dentry, inode);
3101 static void shmem_put_link(void *arg)
3103 mark_page_accessed(arg);
3107 static const char *shmem_get_link(struct dentry *dentry,
3108 struct inode *inode,
3109 struct delayed_call *done)
3111 struct page *page = NULL;
3114 page = find_get_page(inode->i_mapping, 0);
3116 return ERR_PTR(-ECHILD);
3117 if (PageHWPoison(page) ||
3118 !PageUptodate(page)) {
3120 return ERR_PTR(-ECHILD);
3123 error = shmem_getpage(inode, 0, &page, SGP_READ);
3125 return ERR_PTR(error);
3127 return ERR_PTR(-ECHILD);
3128 if (PageHWPoison(page)) {
3131 return ERR_PTR(-ECHILD);
3135 set_delayed_call(done, shmem_put_link, page);
3136 return page_address(page);
3139 #ifdef CONFIG_TMPFS_XATTR
3141 * Superblocks without xattr inode operations may get some security.* xattr
3142 * support from the LSM "for free". As soon as we have any other xattrs
3143 * like ACLs, we also need to implement the security.* handlers at
3144 * filesystem level, though.
3148 * Callback for security_inode_init_security() for acquiring xattrs.
3150 static int shmem_initxattrs(struct inode *inode,
3151 const struct xattr *xattr_array,
3154 struct shmem_inode_info *info = SHMEM_I(inode);
3155 const struct xattr *xattr;
3156 struct simple_xattr *new_xattr;
3159 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3160 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3164 len = strlen(xattr->name) + 1;
3165 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3167 if (!new_xattr->name) {
3172 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3173 XATTR_SECURITY_PREFIX_LEN);
3174 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3177 simple_xattr_list_add(&info->xattrs, new_xattr);
3183 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3184 struct dentry *unused, struct inode *inode,
3185 const char *name, void *buffer, size_t size)
3187 struct shmem_inode_info *info = SHMEM_I(inode);
3189 name = xattr_full_name(handler, name);
3190 return simple_xattr_get(&info->xattrs, name, buffer, size);
3193 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3194 struct user_namespace *mnt_userns,
3195 struct dentry *unused, struct inode *inode,
3196 const char *name, const void *value,
3197 size_t size, int flags)
3199 struct shmem_inode_info *info = SHMEM_I(inode);
3201 name = xattr_full_name(handler, name);
3202 return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
3205 static const struct xattr_handler shmem_security_xattr_handler = {
3206 .prefix = XATTR_SECURITY_PREFIX,
3207 .get = shmem_xattr_handler_get,
3208 .set = shmem_xattr_handler_set,
3211 static const struct xattr_handler shmem_trusted_xattr_handler = {
3212 .prefix = XATTR_TRUSTED_PREFIX,
3213 .get = shmem_xattr_handler_get,
3214 .set = shmem_xattr_handler_set,
3217 static const struct xattr_handler *shmem_xattr_handlers[] = {
3218 #ifdef CONFIG_TMPFS_POSIX_ACL
3219 &posix_acl_access_xattr_handler,
3220 &posix_acl_default_xattr_handler,
3222 &shmem_security_xattr_handler,
3223 &shmem_trusted_xattr_handler,
3227 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3229 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3230 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3232 #endif /* CONFIG_TMPFS_XATTR */
3234 static const struct inode_operations shmem_short_symlink_operations = {
3235 .getattr = shmem_getattr,
3236 .get_link = simple_get_link,
3237 #ifdef CONFIG_TMPFS_XATTR
3238 .listxattr = shmem_listxattr,
3242 static const struct inode_operations shmem_symlink_inode_operations = {
3243 .getattr = shmem_getattr,
3244 .get_link = shmem_get_link,
3245 #ifdef CONFIG_TMPFS_XATTR
3246 .listxattr = shmem_listxattr,
3250 static struct dentry *shmem_get_parent(struct dentry *child)
3252 return ERR_PTR(-ESTALE);
3255 static int shmem_match(struct inode *ino, void *vfh)
3259 inum = (inum << 32) | fh[1];
3260 return ino->i_ino == inum && fh[0] == ino->i_generation;
3263 /* Find any alias of inode, but prefer a hashed alias */
3264 static struct dentry *shmem_find_alias(struct inode *inode)
3266 struct dentry *alias = d_find_alias(inode);
3268 return alias ?: d_find_any_alias(inode);
3272 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3273 struct fid *fid, int fh_len, int fh_type)
3275 struct inode *inode;
3276 struct dentry *dentry = NULL;
3283 inum = (inum << 32) | fid->raw[1];
3285 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3286 shmem_match, fid->raw);
3288 dentry = shmem_find_alias(inode);
3295 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3296 struct inode *parent)
3300 return FILEID_INVALID;
3303 if (inode_unhashed(inode)) {
3304 /* Unfortunately insert_inode_hash is not idempotent,
3305 * so as we hash inodes here rather than at creation
3306 * time, we need a lock to ensure we only try
3309 static DEFINE_SPINLOCK(lock);
3311 if (inode_unhashed(inode))
3312 __insert_inode_hash(inode,
3313 inode->i_ino + inode->i_generation);
3317 fh[0] = inode->i_generation;
3318 fh[1] = inode->i_ino;
3319 fh[2] = ((__u64)inode->i_ino) >> 32;
3325 static const struct export_operations shmem_export_ops = {
3326 .get_parent = shmem_get_parent,
3327 .encode_fh = shmem_encode_fh,
3328 .fh_to_dentry = shmem_fh_to_dentry,
3344 static const struct constant_table shmem_param_enums_huge[] = {
3345 {"never", SHMEM_HUGE_NEVER },
3346 {"always", SHMEM_HUGE_ALWAYS },
3347 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3348 {"advise", SHMEM_HUGE_ADVISE },
3352 const struct fs_parameter_spec shmem_fs_parameters[] = {
3353 fsparam_u32 ("gid", Opt_gid),
3354 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3355 fsparam_u32oct("mode", Opt_mode),
3356 fsparam_string("mpol", Opt_mpol),
3357 fsparam_string("nr_blocks", Opt_nr_blocks),
3358 fsparam_string("nr_inodes", Opt_nr_inodes),
3359 fsparam_string("size", Opt_size),
3360 fsparam_u32 ("uid", Opt_uid),
3361 fsparam_flag ("inode32", Opt_inode32),
3362 fsparam_flag ("inode64", Opt_inode64),
3366 static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3368 struct shmem_options *ctx = fc->fs_private;
3369 struct fs_parse_result result;
3370 unsigned long long size;
3374 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3380 size = memparse(param->string, &rest);
3382 size <<= PAGE_SHIFT;
3383 size *= totalram_pages();
3389 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3390 ctx->seen |= SHMEM_SEEN_BLOCKS;
3393 ctx->blocks = memparse(param->string, &rest);
3394 if (*rest || ctx->blocks > S64_MAX)
3396 ctx->seen |= SHMEM_SEEN_BLOCKS;
3399 ctx->inodes = memparse(param->string, &rest);
3402 ctx->seen |= SHMEM_SEEN_INODES;
3405 ctx->mode = result.uint_32 & 07777;
3408 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
3409 if (!uid_valid(ctx->uid))
3413 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
3414 if (!gid_valid(ctx->gid))
3418 ctx->huge = result.uint_32;
3419 if (ctx->huge != SHMEM_HUGE_NEVER &&
3420 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
3421 has_transparent_hugepage()))
3422 goto unsupported_parameter;
3423 ctx->seen |= SHMEM_SEEN_HUGE;
3426 if (IS_ENABLED(CONFIG_NUMA)) {
3427 mpol_put(ctx->mpol);
3429 if (mpol_parse_str(param->string, &ctx->mpol))
3433 goto unsupported_parameter;
3435 ctx->full_inums = false;
3436 ctx->seen |= SHMEM_SEEN_INUMS;
3439 if (sizeof(ino_t) < 8) {
3441 "Cannot use inode64 with <64bit inums in kernel\n");
3443 ctx->full_inums = true;
3444 ctx->seen |= SHMEM_SEEN_INUMS;
3449 unsupported_parameter:
3450 return invalfc(fc, "Unsupported parameter '%s'", param->key);
3452 return invalfc(fc, "Bad value for '%s'", param->key);
3455 static int shmem_parse_options(struct fs_context *fc, void *data)
3457 char *options = data;
3460 int err = security_sb_eat_lsm_opts(options, &fc->security);
3465 while (options != NULL) {
3466 char *this_char = options;
3469 * NUL-terminate this option: unfortunately,
3470 * mount options form a comma-separated list,
3471 * but mpol's nodelist may also contain commas.
3473 options = strchr(options, ',');
3474 if (options == NULL)
3477 if (!isdigit(*options)) {
3483 char *value = strchr(this_char, '=');
3489 len = strlen(value);
3491 err = vfs_parse_fs_string(fc, this_char, value, len);
3500 * Reconfigure a shmem filesystem.
3502 * Note that we disallow change from limited->unlimited blocks/inodes while any
3503 * are in use; but we must separately disallow unlimited->limited, because in
3504 * that case we have no record of how much is already in use.
3506 static int shmem_reconfigure(struct fs_context *fc)
3508 struct shmem_options *ctx = fc->fs_private;
3509 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
3510 unsigned long inodes;
3511 struct mempolicy *mpol = NULL;
3514 raw_spin_lock(&sbinfo->stat_lock);
3515 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3517 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
3518 if (!sbinfo->max_blocks) {
3519 err = "Cannot retroactively limit size";
3522 if (percpu_counter_compare(&sbinfo->used_blocks,
3524 err = "Too small a size for current use";
3528 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
3529 if (!sbinfo->max_inodes) {
3530 err = "Cannot retroactively limit inodes";
3533 if (ctx->inodes < inodes) {
3534 err = "Too few inodes for current use";
3539 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
3540 sbinfo->next_ino > UINT_MAX) {
3541 err = "Current inum too high to switch to 32-bit inums";
3545 if (ctx->seen & SHMEM_SEEN_HUGE)
3546 sbinfo->huge = ctx->huge;
3547 if (ctx->seen & SHMEM_SEEN_INUMS)
3548 sbinfo->full_inums = ctx->full_inums;
3549 if (ctx->seen & SHMEM_SEEN_BLOCKS)
3550 sbinfo->max_blocks = ctx->blocks;
3551 if (ctx->seen & SHMEM_SEEN_INODES) {
3552 sbinfo->max_inodes = ctx->inodes;
3553 sbinfo->free_inodes = ctx->inodes - inodes;
3557 * Preserve previous mempolicy unless mpol remount option was specified.
3560 mpol = sbinfo->mpol;
3561 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
3564 raw_spin_unlock(&sbinfo->stat_lock);
3568 raw_spin_unlock(&sbinfo->stat_lock);
3569 return invalfc(fc, "%s", err);
3572 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3574 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3576 if (sbinfo->max_blocks != shmem_default_max_blocks())
3577 seq_printf(seq, ",size=%luk",
3578 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3579 if (sbinfo->max_inodes != shmem_default_max_inodes())
3580 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3581 if (sbinfo->mode != (0777 | S_ISVTX))
3582 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3583 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3584 seq_printf(seq, ",uid=%u",
3585 from_kuid_munged(&init_user_ns, sbinfo->uid));
3586 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3587 seq_printf(seq, ",gid=%u",
3588 from_kgid_munged(&init_user_ns, sbinfo->gid));
3591 * Showing inode{64,32} might be useful even if it's the system default,
3592 * since then people don't have to resort to checking both here and
3593 * /proc/config.gz to confirm 64-bit inums were successfully applied
3594 * (which may not even exist if IKCONFIG_PROC isn't enabled).
3596 * We hide it when inode64 isn't the default and we are using 32-bit
3597 * inodes, since that probably just means the feature isn't even under
3602 * +-----------------+-----------------+
3603 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
3604 * +------------------+-----------------+-----------------+
3605 * | full_inums=true | show | show |
3606 * | full_inums=false | show | hide |
3607 * +------------------+-----------------+-----------------+
3610 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
3611 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
3612 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3613 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3615 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3617 shmem_show_mpol(seq, sbinfo->mpol);
3621 #endif /* CONFIG_TMPFS */
3623 static void shmem_put_super(struct super_block *sb)
3625 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3627 free_percpu(sbinfo->ino_batch);
3628 percpu_counter_destroy(&sbinfo->used_blocks);
3629 mpol_put(sbinfo->mpol);
3631 sb->s_fs_info = NULL;
3634 static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
3636 struct shmem_options *ctx = fc->fs_private;
3637 struct inode *inode;
3638 struct shmem_sb_info *sbinfo;
3640 /* Round up to L1_CACHE_BYTES to resist false sharing */
3641 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3642 L1_CACHE_BYTES), GFP_KERNEL);
3646 sb->s_fs_info = sbinfo;
3650 * Per default we only allow half of the physical ram per
3651 * tmpfs instance, limiting inodes to one per page of lowmem;
3652 * but the internal instance is left unlimited.
3654 if (!(sb->s_flags & SB_KERNMOUNT)) {
3655 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
3656 ctx->blocks = shmem_default_max_blocks();
3657 if (!(ctx->seen & SHMEM_SEEN_INODES))
3658 ctx->inodes = shmem_default_max_inodes();
3659 if (!(ctx->seen & SHMEM_SEEN_INUMS))
3660 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
3662 sb->s_flags |= SB_NOUSER;
3664 sb->s_export_op = &shmem_export_ops;
3665 sb->s_flags |= SB_NOSEC;
3667 sb->s_flags |= SB_NOUSER;
3669 sbinfo->max_blocks = ctx->blocks;
3670 sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
3671 if (sb->s_flags & SB_KERNMOUNT) {
3672 sbinfo->ino_batch = alloc_percpu(ino_t);
3673 if (!sbinfo->ino_batch)
3676 sbinfo->uid = ctx->uid;
3677 sbinfo->gid = ctx->gid;
3678 sbinfo->full_inums = ctx->full_inums;
3679 sbinfo->mode = ctx->mode;
3680 sbinfo->huge = ctx->huge;
3681 sbinfo->mpol = ctx->mpol;
3684 raw_spin_lock_init(&sbinfo->stat_lock);
3685 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3687 spin_lock_init(&sbinfo->shrinklist_lock);
3688 INIT_LIST_HEAD(&sbinfo->shrinklist);
3690 sb->s_maxbytes = MAX_LFS_FILESIZE;
3691 sb->s_blocksize = PAGE_SIZE;
3692 sb->s_blocksize_bits = PAGE_SHIFT;
3693 sb->s_magic = TMPFS_MAGIC;
3694 sb->s_op = &shmem_ops;
3695 sb->s_time_gran = 1;
3696 #ifdef CONFIG_TMPFS_XATTR
3697 sb->s_xattr = shmem_xattr_handlers;
3699 #ifdef CONFIG_TMPFS_POSIX_ACL
3700 sb->s_flags |= SB_POSIXACL;
3702 uuid_gen(&sb->s_uuid);
3704 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3707 inode->i_uid = sbinfo->uid;
3708 inode->i_gid = sbinfo->gid;
3709 sb->s_root = d_make_root(inode);
3715 shmem_put_super(sb);
3719 static int shmem_get_tree(struct fs_context *fc)
3721 return get_tree_nodev(fc, shmem_fill_super);
3724 static void shmem_free_fc(struct fs_context *fc)
3726 struct shmem_options *ctx = fc->fs_private;
3729 mpol_put(ctx->mpol);
3734 static const struct fs_context_operations shmem_fs_context_ops = {
3735 .free = shmem_free_fc,
3736 .get_tree = shmem_get_tree,
3738 .parse_monolithic = shmem_parse_options,
3739 .parse_param = shmem_parse_one,
3740 .reconfigure = shmem_reconfigure,
3744 static struct kmem_cache *shmem_inode_cachep;
3746 static struct inode *shmem_alloc_inode(struct super_block *sb)
3748 struct shmem_inode_info *info;
3749 info = alloc_inode_sb(sb, shmem_inode_cachep, GFP_KERNEL);
3752 return &info->vfs_inode;
3755 static void shmem_free_in_core_inode(struct inode *inode)
3757 if (S_ISLNK(inode->i_mode))
3758 kfree(inode->i_link);
3759 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3762 static void shmem_destroy_inode(struct inode *inode)
3764 if (S_ISREG(inode->i_mode))
3765 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3768 static void shmem_init_inode(void *foo)
3770 struct shmem_inode_info *info = foo;
3771 inode_init_once(&info->vfs_inode);
3774 static void shmem_init_inodecache(void)
3776 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3777 sizeof(struct shmem_inode_info),
3778 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3781 static void shmem_destroy_inodecache(void)
3783 kmem_cache_destroy(shmem_inode_cachep);
3786 /* Keep the page in page cache instead of truncating it */
3787 static int shmem_error_remove_page(struct address_space *mapping,
3793 const struct address_space_operations shmem_aops = {
3794 .writepage = shmem_writepage,
3795 .dirty_folio = noop_dirty_folio,
3797 .write_begin = shmem_write_begin,
3798 .write_end = shmem_write_end,
3800 #ifdef CONFIG_MIGRATION
3801 .migrate_folio = migrate_folio,
3803 .error_remove_page = shmem_error_remove_page,
3805 EXPORT_SYMBOL(shmem_aops);
3807 static const struct file_operations shmem_file_operations = {
3809 .get_unmapped_area = shmem_get_unmapped_area,
3811 .llseek = shmem_file_llseek,
3812 .read_iter = shmem_file_read_iter,
3813 .write_iter = generic_file_write_iter,
3814 .fsync = noop_fsync,
3815 .splice_read = generic_file_splice_read,
3816 .splice_write = iter_file_splice_write,
3817 .fallocate = shmem_fallocate,
3821 static const struct inode_operations shmem_inode_operations = {
3822 .getattr = shmem_getattr,
3823 .setattr = shmem_setattr,
3824 #ifdef CONFIG_TMPFS_XATTR
3825 .listxattr = shmem_listxattr,
3826 .set_acl = simple_set_acl,
3830 static const struct inode_operations shmem_dir_inode_operations = {
3832 .getattr = shmem_getattr,
3833 .create = shmem_create,
3834 .lookup = simple_lookup,
3836 .unlink = shmem_unlink,
3837 .symlink = shmem_symlink,
3838 .mkdir = shmem_mkdir,
3839 .rmdir = shmem_rmdir,
3840 .mknod = shmem_mknod,
3841 .rename = shmem_rename2,
3842 .tmpfile = shmem_tmpfile,
3844 #ifdef CONFIG_TMPFS_XATTR
3845 .listxattr = shmem_listxattr,
3847 #ifdef CONFIG_TMPFS_POSIX_ACL
3848 .setattr = shmem_setattr,
3849 .set_acl = simple_set_acl,
3853 static const struct inode_operations shmem_special_inode_operations = {
3854 .getattr = shmem_getattr,
3855 #ifdef CONFIG_TMPFS_XATTR
3856 .listxattr = shmem_listxattr,
3858 #ifdef CONFIG_TMPFS_POSIX_ACL
3859 .setattr = shmem_setattr,
3860 .set_acl = simple_set_acl,
3864 static const struct super_operations shmem_ops = {
3865 .alloc_inode = shmem_alloc_inode,
3866 .free_inode = shmem_free_in_core_inode,
3867 .destroy_inode = shmem_destroy_inode,
3869 .statfs = shmem_statfs,
3870 .show_options = shmem_show_options,
3872 .evict_inode = shmem_evict_inode,
3873 .drop_inode = generic_delete_inode,
3874 .put_super = shmem_put_super,
3875 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3876 .nr_cached_objects = shmem_unused_huge_count,
3877 .free_cached_objects = shmem_unused_huge_scan,
3881 static const struct vm_operations_struct shmem_vm_ops = {
3882 .fault = shmem_fault,
3883 .map_pages = filemap_map_pages,
3885 .set_policy = shmem_set_policy,
3886 .get_policy = shmem_get_policy,
3890 int shmem_init_fs_context(struct fs_context *fc)
3892 struct shmem_options *ctx;
3894 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
3898 ctx->mode = 0777 | S_ISVTX;
3899 ctx->uid = current_fsuid();
3900 ctx->gid = current_fsgid();
3902 fc->fs_private = ctx;
3903 fc->ops = &shmem_fs_context_ops;
3907 static struct file_system_type shmem_fs_type = {
3908 .owner = THIS_MODULE,
3910 .init_fs_context = shmem_init_fs_context,
3912 .parameters = shmem_fs_parameters,
3914 .kill_sb = kill_litter_super,
3915 .fs_flags = FS_USERNS_MOUNT,
3918 void __init shmem_init(void)
3922 shmem_init_inodecache();
3924 error = register_filesystem(&shmem_fs_type);
3926 pr_err("Could not register tmpfs\n");
3930 shm_mnt = kern_mount(&shmem_fs_type);
3931 if (IS_ERR(shm_mnt)) {
3932 error = PTR_ERR(shm_mnt);
3933 pr_err("Could not kern_mount tmpfs\n");
3937 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3938 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
3939 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3941 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
3946 unregister_filesystem(&shmem_fs_type);
3948 shmem_destroy_inodecache();
3949 shm_mnt = ERR_PTR(error);
3952 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
3953 static ssize_t shmem_enabled_show(struct kobject *kobj,
3954 struct kobj_attribute *attr, char *buf)
3956 static const int values[] = {
3958 SHMEM_HUGE_WITHIN_SIZE,
3967 for (i = 0; i < ARRAY_SIZE(values); i++) {
3968 len += sysfs_emit_at(buf, len,
3969 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
3971 shmem_format_huge(values[i]));
3974 len += sysfs_emit_at(buf, len, "\n");
3979 static ssize_t shmem_enabled_store(struct kobject *kobj,
3980 struct kobj_attribute *attr, const char *buf, size_t count)
3985 if (count + 1 > sizeof(tmp))
3987 memcpy(tmp, buf, count);
3989 if (count && tmp[count - 1] == '\n')
3990 tmp[count - 1] = '\0';
3992 huge = shmem_parse_huge(tmp);
3993 if (huge == -EINVAL)
3995 if (!has_transparent_hugepage() &&
3996 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4000 if (shmem_huge > SHMEM_HUGE_DENY)
4001 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4005 struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
4006 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4008 #else /* !CONFIG_SHMEM */
4011 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4013 * This is intended for small system where the benefits of the full
4014 * shmem code (swap-backed and resource-limited) are outweighed by
4015 * their complexity. On systems without swap this code should be
4016 * effectively equivalent, but much lighter weight.
4019 static struct file_system_type shmem_fs_type = {
4021 .init_fs_context = ramfs_init_fs_context,
4022 .parameters = ramfs_fs_parameters,
4023 .kill_sb = kill_litter_super,
4024 .fs_flags = FS_USERNS_MOUNT,
4027 void __init shmem_init(void)
4029 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4031 shm_mnt = kern_mount(&shmem_fs_type);
4032 BUG_ON(IS_ERR(shm_mnt));
4035 int shmem_unuse(unsigned int type)
4040 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
4045 void shmem_unlock_mapping(struct address_space *mapping)
4050 unsigned long shmem_get_unmapped_area(struct file *file,
4051 unsigned long addr, unsigned long len,
4052 unsigned long pgoff, unsigned long flags)
4054 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4058 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4060 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4062 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4064 #define shmem_vm_ops generic_file_vm_ops
4065 #define shmem_file_operations ramfs_file_operations
4066 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4067 #define shmem_acct_size(flags, size) 0
4068 #define shmem_unacct_size(flags, size) do {} while (0)
4070 #endif /* CONFIG_SHMEM */
4074 static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4075 unsigned long flags, unsigned int i_flags)
4077 struct inode *inode;
4081 return ERR_CAST(mnt);
4083 if (size < 0 || size > MAX_LFS_FILESIZE)
4084 return ERR_PTR(-EINVAL);
4086 if (shmem_acct_size(flags, size))
4087 return ERR_PTR(-ENOMEM);
4089 inode = shmem_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0,
4091 if (unlikely(!inode)) {
4092 shmem_unacct_size(flags, size);
4093 return ERR_PTR(-ENOSPC);
4095 inode->i_flags |= i_flags;
4096 inode->i_size = size;
4097 clear_nlink(inode); /* It is unlinked */
4098 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4100 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4101 &shmem_file_operations);
4108 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4109 * kernel internal. There will be NO LSM permission checks against the
4110 * underlying inode. So users of this interface must do LSM checks at a
4111 * higher layer. The users are the big_key and shm implementations. LSM
4112 * checks are provided at the key or shm level rather than the inode.
4113 * @name: name for dentry (to be seen in /proc/<pid>/maps
4114 * @size: size to be set for the file
4115 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4117 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4119 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4123 * shmem_file_setup - get an unlinked file living in tmpfs
4124 * @name: name for dentry (to be seen in /proc/<pid>/maps
4125 * @size: size to be set for the file
4126 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4128 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4130 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4132 EXPORT_SYMBOL_GPL(shmem_file_setup);
4135 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4136 * @mnt: the tmpfs mount where the file will be created
4137 * @name: name for dentry (to be seen in /proc/<pid>/maps
4138 * @size: size to be set for the file
4139 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4141 struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4142 loff_t size, unsigned long flags)
4144 return __shmem_file_setup(mnt, name, size, flags, 0);
4146 EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4149 * shmem_zero_setup - setup a shared anonymous mapping
4150 * @vma: the vma to be mmapped is prepared by do_mmap
4152 int shmem_zero_setup(struct vm_area_struct *vma)
4155 loff_t size = vma->vm_end - vma->vm_start;
4158 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4159 * between XFS directory reading and selinux: since this file is only
4160 * accessible to the user through its mapping, use S_PRIVATE flag to
4161 * bypass file security, in the same way as shmem_kernel_file_setup().
4163 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4165 return PTR_ERR(file);
4169 vma->vm_file = file;
4170 vma->vm_ops = &shmem_vm_ops;
4176 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4177 * @mapping: the page's address_space
4178 * @index: the page index
4179 * @gfp: the page allocator flags to use if allocating
4181 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4182 * with any new page allocations done using the specified allocation flags.
4183 * But read_cache_page_gfp() uses the ->read_folio() method: which does not
4184 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4185 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4187 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4188 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4190 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4191 pgoff_t index, gfp_t gfp)
4194 struct inode *inode = mapping->host;
4198 BUG_ON(!shmem_mapping(mapping));
4199 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4200 gfp, NULL, NULL, NULL);
4202 return ERR_PTR(error);
4205 if (PageHWPoison(page)) {
4207 return ERR_PTR(-EIO);
4213 * The tiny !SHMEM case uses ramfs without swap
4215 return read_cache_page_gfp(mapping, index, gfp);
4218 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);