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>
31 #include <linux/fileattr.h>
33 #include <linux/random.h>
34 #include <linux/sched/signal.h>
35 #include <linux/export.h>
36 #include <linux/shmem_fs.h>
37 #include <linux/swap.h>
38 #include <linux/uio.h>
39 #include <linux/hugetlb.h>
40 #include <linux/fs_parser.h>
41 #include <linux/swapfile.h>
42 #include <linux/iversion.h>
45 static struct vfsmount *shm_mnt;
49 * This virtual memory filesystem is heavily based on the ramfs. It
50 * extends ramfs by the ability to use swap and honor resource limits
51 * which makes it a completely usable filesystem.
54 #include <linux/xattr.h>
55 #include <linux/exportfs.h>
56 #include <linux/posix_acl.h>
57 #include <linux/posix_acl_xattr.h>
58 #include <linux/mman.h>
59 #include <linux/string.h>
60 #include <linux/slab.h>
61 #include <linux/backing-dev.h>
62 #include <linux/writeback.h>
63 #include <linux/pagevec.h>
64 #include <linux/percpu_counter.h>
65 #include <linux/falloc.h>
66 #include <linux/splice.h>
67 #include <linux/security.h>
68 #include <linux/swapops.h>
69 #include <linux/mempolicy.h>
70 #include <linux/namei.h>
71 #include <linux/ctype.h>
72 #include <linux/migrate.h>
73 #include <linux/highmem.h>
74 #include <linux/seq_file.h>
75 #include <linux/magic.h>
76 #include <linux/syscalls.h>
77 #include <linux/fcntl.h>
78 #include <uapi/linux/memfd.h>
79 #include <linux/rmap.h>
80 #include <linux/uuid.h>
81 #include <linux/quotaops.h>
83 #include <linux/uaccess.h>
87 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
88 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
90 /* Pretend that each entry is of this size in directory's i_size */
91 #define BOGO_DIRENT_SIZE 20
93 /* Pretend that one inode + its dentry occupy this much memory */
94 #define BOGO_INODE_SIZE 1024
96 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
97 #define SHORT_SYMLINK_LEN 128
100 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
101 * inode->i_private (with i_rwsem making sure that it has only one user at
102 * a time): we would prefer not to enlarge the shmem inode just for that.
104 struct shmem_falloc {
105 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
106 pgoff_t start; /* start of range currently being fallocated */
107 pgoff_t next; /* the next page offset to be fallocated */
108 pgoff_t nr_falloced; /* how many new pages have been fallocated */
109 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
112 struct shmem_options {
113 unsigned long long blocks;
114 unsigned long long inodes;
115 struct mempolicy *mpol;
123 unsigned short quota_types;
124 struct shmem_quota_limits qlimits;
125 #define SHMEM_SEEN_BLOCKS 1
126 #define SHMEM_SEEN_INODES 2
127 #define SHMEM_SEEN_HUGE 4
128 #define SHMEM_SEEN_INUMS 8
129 #define SHMEM_SEEN_NOSWAP 16
130 #define SHMEM_SEEN_QUOTA 32
134 static unsigned long shmem_default_max_blocks(void)
136 return totalram_pages() / 2;
139 static unsigned long shmem_default_max_inodes(void)
141 unsigned long nr_pages = totalram_pages();
143 return min3(nr_pages - totalhigh_pages(), nr_pages / 2,
144 ULONG_MAX / BOGO_INODE_SIZE);
148 static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
149 struct folio **foliop, enum sgp_type sgp,
150 gfp_t gfp, struct vm_area_struct *vma,
151 vm_fault_t *fault_type);
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_get_folio 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 int 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);
216 if (shmem_acct_block(info->flags, pages))
219 might_sleep(); /* when quotas */
220 if (sbinfo->max_blocks) {
221 if (percpu_counter_compare(&sbinfo->used_blocks,
222 sbinfo->max_blocks - pages) > 0)
225 err = dquot_alloc_block_nodirty(inode, pages);
229 percpu_counter_add(&sbinfo->used_blocks, pages);
231 err = dquot_alloc_block_nodirty(inode, pages);
239 shmem_unacct_blocks(info->flags, pages);
243 static void shmem_inode_unacct_blocks(struct inode *inode, long pages)
245 struct shmem_inode_info *info = SHMEM_I(inode);
246 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
248 might_sleep(); /* when quotas */
249 dquot_free_block_nodirty(inode, pages);
251 if (sbinfo->max_blocks)
252 percpu_counter_sub(&sbinfo->used_blocks, pages);
253 shmem_unacct_blocks(info->flags, pages);
256 static const struct super_operations shmem_ops;
257 const struct address_space_operations shmem_aops;
258 static const struct file_operations shmem_file_operations;
259 static const struct inode_operations shmem_inode_operations;
260 static const struct inode_operations shmem_dir_inode_operations;
261 static const struct inode_operations shmem_special_inode_operations;
262 static const struct vm_operations_struct shmem_vm_ops;
263 static const struct vm_operations_struct shmem_anon_vm_ops;
264 static struct file_system_type shmem_fs_type;
266 bool vma_is_anon_shmem(struct vm_area_struct *vma)
268 return vma->vm_ops == &shmem_anon_vm_ops;
271 bool vma_is_shmem(struct vm_area_struct *vma)
273 return vma_is_anon_shmem(vma) || vma->vm_ops == &shmem_vm_ops;
276 static LIST_HEAD(shmem_swaplist);
277 static DEFINE_MUTEX(shmem_swaplist_mutex);
279 #ifdef CONFIG_TMPFS_QUOTA
281 static int shmem_enable_quotas(struct super_block *sb,
282 unsigned short quota_types)
286 sb_dqopt(sb)->flags |= DQUOT_QUOTA_SYS_FILE | DQUOT_NOLIST_DIRTY;
287 for (type = 0; type < SHMEM_MAXQUOTAS; type++) {
288 if (!(quota_types & (1 << type)))
290 err = dquot_load_quota_sb(sb, type, QFMT_SHMEM,
291 DQUOT_USAGE_ENABLED |
292 DQUOT_LIMITS_ENABLED);
299 pr_warn("tmpfs: failed to enable quota tracking (type=%d, err=%d)\n",
301 for (type--; type >= 0; type--)
302 dquot_quota_off(sb, type);
306 static void shmem_disable_quotas(struct super_block *sb)
310 for (type = 0; type < SHMEM_MAXQUOTAS; type++)
311 dquot_quota_off(sb, type);
314 static struct dquot **shmem_get_dquots(struct inode *inode)
316 return SHMEM_I(inode)->i_dquot;
318 #endif /* CONFIG_TMPFS_QUOTA */
321 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
322 * produces a novel ino for the newly allocated inode.
324 * It may also be called when making a hard link to permit the space needed by
325 * each dentry. However, in that case, no new inode number is needed since that
326 * internally draws from another pool of inode numbers (currently global
327 * get_next_ino()). This case is indicated by passing NULL as inop.
329 #define SHMEM_INO_BATCH 1024
330 static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
332 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
335 if (!(sb->s_flags & SB_KERNMOUNT)) {
336 raw_spin_lock(&sbinfo->stat_lock);
337 if (sbinfo->max_inodes) {
338 if (sbinfo->free_ispace < BOGO_INODE_SIZE) {
339 raw_spin_unlock(&sbinfo->stat_lock);
342 sbinfo->free_ispace -= BOGO_INODE_SIZE;
345 ino = sbinfo->next_ino++;
346 if (unlikely(is_zero_ino(ino)))
347 ino = sbinfo->next_ino++;
348 if (unlikely(!sbinfo->full_inums &&
351 * Emulate get_next_ino uint wraparound for
354 if (IS_ENABLED(CONFIG_64BIT))
355 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
356 __func__, MINOR(sb->s_dev));
357 sbinfo->next_ino = 1;
358 ino = sbinfo->next_ino++;
362 raw_spin_unlock(&sbinfo->stat_lock);
365 * __shmem_file_setup, one of our callers, is lock-free: it
366 * doesn't hold stat_lock in shmem_reserve_inode since
367 * max_inodes is always 0, and is called from potentially
368 * unknown contexts. As such, use a per-cpu batched allocator
369 * which doesn't require the per-sb stat_lock unless we are at
370 * the batch boundary.
372 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
373 * shmem mounts are not exposed to userspace, so we don't need
374 * to worry about things like glibc compatibility.
378 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
380 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
381 raw_spin_lock(&sbinfo->stat_lock);
382 ino = sbinfo->next_ino;
383 sbinfo->next_ino += SHMEM_INO_BATCH;
384 raw_spin_unlock(&sbinfo->stat_lock);
385 if (unlikely(is_zero_ino(ino)))
396 static void shmem_free_inode(struct super_block *sb, size_t freed_ispace)
398 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
399 if (sbinfo->max_inodes) {
400 raw_spin_lock(&sbinfo->stat_lock);
401 sbinfo->free_ispace += BOGO_INODE_SIZE + freed_ispace;
402 raw_spin_unlock(&sbinfo->stat_lock);
407 * shmem_recalc_inode - recalculate the block usage of an inode
408 * @inode: inode to recalc
409 * @alloced: the change in number of pages allocated to inode
410 * @swapped: the change in number of pages swapped from inode
412 * We have to calculate the free blocks since the mm can drop
413 * undirtied hole pages behind our back.
415 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
416 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
418 static void shmem_recalc_inode(struct inode *inode, long alloced, long swapped)
420 struct shmem_inode_info *info = SHMEM_I(inode);
423 spin_lock(&info->lock);
424 info->alloced += alloced;
425 info->swapped += swapped;
426 freed = info->alloced - info->swapped -
427 READ_ONCE(inode->i_mapping->nrpages);
429 * Special case: whereas normally shmem_recalc_inode() is called
430 * after i_mapping->nrpages has already been adjusted (up or down),
431 * shmem_writepage() has to raise swapped before nrpages is lowered -
432 * to stop a racing shmem_recalc_inode() from thinking that a page has
433 * been freed. Compensate here, to avoid the need for a followup call.
438 info->alloced -= freed;
439 spin_unlock(&info->lock);
441 /* The quota case may block */
443 shmem_inode_unacct_blocks(inode, freed);
446 bool shmem_charge(struct inode *inode, long pages)
448 struct address_space *mapping = inode->i_mapping;
450 if (shmem_inode_acct_block(inode, pages))
453 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
454 xa_lock_irq(&mapping->i_pages);
455 mapping->nrpages += pages;
456 xa_unlock_irq(&mapping->i_pages);
458 shmem_recalc_inode(inode, pages, 0);
462 void shmem_uncharge(struct inode *inode, long pages)
464 /* pages argument is currently unused: keep it to help debugging */
465 /* nrpages adjustment done by __filemap_remove_folio() or caller */
467 shmem_recalc_inode(inode, 0, 0);
471 * Replace item expected in xarray by a new item, while holding xa_lock.
473 static int shmem_replace_entry(struct address_space *mapping,
474 pgoff_t index, void *expected, void *replacement)
476 XA_STATE(xas, &mapping->i_pages, index);
479 VM_BUG_ON(!expected);
480 VM_BUG_ON(!replacement);
481 item = xas_load(&xas);
482 if (item != expected)
484 xas_store(&xas, replacement);
489 * Sometimes, before we decide whether to proceed or to fail, we must check
490 * that an entry was not already brought back from swap by a racing thread.
492 * Checking page is not enough: by the time a SwapCache page is locked, it
493 * might be reused, and again be SwapCache, using the same swap as before.
495 static bool shmem_confirm_swap(struct address_space *mapping,
496 pgoff_t index, swp_entry_t swap)
498 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
502 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
505 * disables huge pages for the mount;
507 * enables huge pages for the mount;
508 * SHMEM_HUGE_WITHIN_SIZE:
509 * only allocate huge pages if the page will be fully within i_size,
510 * also respect fadvise()/madvise() hints;
512 * only allocate huge pages if requested with fadvise()/madvise();
515 #define SHMEM_HUGE_NEVER 0
516 #define SHMEM_HUGE_ALWAYS 1
517 #define SHMEM_HUGE_WITHIN_SIZE 2
518 #define SHMEM_HUGE_ADVISE 3
522 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
525 * disables huge on shm_mnt and all mounts, for emergency use;
527 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
530 #define SHMEM_HUGE_DENY (-1)
531 #define SHMEM_HUGE_FORCE (-2)
533 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
534 /* ifdef here to avoid bloating shmem.o when not necessary */
536 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
538 bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
539 struct mm_struct *mm, unsigned long vm_flags)
543 if (!S_ISREG(inode->i_mode))
545 if (mm && ((vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &mm->flags)))
547 if (shmem_huge == SHMEM_HUGE_DENY)
549 if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE)
552 switch (SHMEM_SB(inode->i_sb)->huge) {
553 case SHMEM_HUGE_ALWAYS:
555 case SHMEM_HUGE_WITHIN_SIZE:
556 index = round_up(index + 1, HPAGE_PMD_NR);
557 i_size = round_up(i_size_read(inode), PAGE_SIZE);
558 if (i_size >> PAGE_SHIFT >= index)
561 case SHMEM_HUGE_ADVISE:
562 if (mm && (vm_flags & VM_HUGEPAGE))
570 #if defined(CONFIG_SYSFS)
571 static int shmem_parse_huge(const char *str)
573 if (!strcmp(str, "never"))
574 return SHMEM_HUGE_NEVER;
575 if (!strcmp(str, "always"))
576 return SHMEM_HUGE_ALWAYS;
577 if (!strcmp(str, "within_size"))
578 return SHMEM_HUGE_WITHIN_SIZE;
579 if (!strcmp(str, "advise"))
580 return SHMEM_HUGE_ADVISE;
581 if (!strcmp(str, "deny"))
582 return SHMEM_HUGE_DENY;
583 if (!strcmp(str, "force"))
584 return SHMEM_HUGE_FORCE;
589 #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
590 static const char *shmem_format_huge(int huge)
593 case SHMEM_HUGE_NEVER:
595 case SHMEM_HUGE_ALWAYS:
597 case SHMEM_HUGE_WITHIN_SIZE:
598 return "within_size";
599 case SHMEM_HUGE_ADVISE:
601 case SHMEM_HUGE_DENY:
603 case SHMEM_HUGE_FORCE:
612 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
613 struct shrink_control *sc, unsigned long nr_to_split)
615 LIST_HEAD(list), *pos, *next;
616 LIST_HEAD(to_remove);
618 struct shmem_inode_info *info;
620 unsigned long batch = sc ? sc->nr_to_scan : 128;
623 if (list_empty(&sbinfo->shrinklist))
626 spin_lock(&sbinfo->shrinklist_lock);
627 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
628 info = list_entry(pos, struct shmem_inode_info, shrinklist);
631 inode = igrab(&info->vfs_inode);
633 /* inode is about to be evicted */
635 list_del_init(&info->shrinklist);
639 /* Check if there's anything to gain */
640 if (round_up(inode->i_size, PAGE_SIZE) ==
641 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
642 list_move(&info->shrinklist, &to_remove);
646 list_move(&info->shrinklist, &list);
648 sbinfo->shrinklist_len--;
652 spin_unlock(&sbinfo->shrinklist_lock);
654 list_for_each_safe(pos, next, &to_remove) {
655 info = list_entry(pos, struct shmem_inode_info, shrinklist);
656 inode = &info->vfs_inode;
657 list_del_init(&info->shrinklist);
661 list_for_each_safe(pos, next, &list) {
665 info = list_entry(pos, struct shmem_inode_info, shrinklist);
666 inode = &info->vfs_inode;
668 if (nr_to_split && split >= nr_to_split)
671 index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
672 folio = filemap_get_folio(inode->i_mapping, index);
676 /* No huge page at the end of the file: nothing to split */
677 if (!folio_test_large(folio)) {
683 * Move the inode on the list back to shrinklist if we failed
684 * to lock the page at this time.
686 * Waiting for the lock may lead to deadlock in the
689 if (!folio_trylock(folio)) {
694 ret = split_folio(folio);
698 /* If split failed move the inode on the list back to shrinklist */
704 list_del_init(&info->shrinklist);
708 * Make sure the inode is either on the global list or deleted
709 * from any local list before iput() since it could be deleted
710 * in another thread once we put the inode (then the local list
713 spin_lock(&sbinfo->shrinklist_lock);
714 list_move(&info->shrinklist, &sbinfo->shrinklist);
715 sbinfo->shrinklist_len++;
716 spin_unlock(&sbinfo->shrinklist_lock);
724 static long shmem_unused_huge_scan(struct super_block *sb,
725 struct shrink_control *sc)
727 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
729 if (!READ_ONCE(sbinfo->shrinklist_len))
732 return shmem_unused_huge_shrink(sbinfo, sc, 0);
735 static long shmem_unused_huge_count(struct super_block *sb,
736 struct shrink_control *sc)
738 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
739 return READ_ONCE(sbinfo->shrinklist_len);
741 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
743 #define shmem_huge SHMEM_HUGE_DENY
745 bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
746 struct mm_struct *mm, unsigned long vm_flags)
751 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
752 struct shrink_control *sc, unsigned long nr_to_split)
756 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
759 * Like filemap_add_folio, but error if expected item has gone.
761 static int shmem_add_to_page_cache(struct folio *folio,
762 struct address_space *mapping,
763 pgoff_t index, void *expected, gfp_t gfp,
764 struct mm_struct *charge_mm)
766 XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
767 long nr = folio_nr_pages(folio);
770 VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
771 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
772 VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
773 VM_BUG_ON(expected && folio_test_large(folio));
775 folio_ref_add(folio, nr);
776 folio->mapping = mapping;
777 folio->index = index;
779 if (!folio_test_swapcache(folio)) {
780 error = mem_cgroup_charge(folio, charge_mm, gfp);
782 if (folio_test_pmd_mappable(folio)) {
783 count_vm_event(THP_FILE_FALLBACK);
784 count_vm_event(THP_FILE_FALLBACK_CHARGE);
789 folio_throttle_swaprate(folio, gfp);
793 if (expected != xas_find_conflict(&xas)) {
794 xas_set_err(&xas, -EEXIST);
797 if (expected && xas_find_conflict(&xas)) {
798 xas_set_err(&xas, -EEXIST);
801 xas_store(&xas, folio);
804 if (folio_test_pmd_mappable(folio)) {
805 count_vm_event(THP_FILE_ALLOC);
806 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr);
808 mapping->nrpages += nr;
809 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);
810 __lruvec_stat_mod_folio(folio, NR_SHMEM, nr);
812 xas_unlock_irq(&xas);
813 } while (xas_nomem(&xas, gfp));
815 if (xas_error(&xas)) {
816 error = xas_error(&xas);
822 folio->mapping = NULL;
823 folio_ref_sub(folio, nr);
828 * Like delete_from_page_cache, but substitutes swap for @folio.
830 static void shmem_delete_from_page_cache(struct folio *folio, void *radswap)
832 struct address_space *mapping = folio->mapping;
833 long nr = folio_nr_pages(folio);
836 xa_lock_irq(&mapping->i_pages);
837 error = shmem_replace_entry(mapping, folio->index, folio, radswap);
838 folio->mapping = NULL;
839 mapping->nrpages -= nr;
840 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, -nr);
841 __lruvec_stat_mod_folio(folio, NR_SHMEM, -nr);
842 xa_unlock_irq(&mapping->i_pages);
848 * Remove swap entry from page cache, free the swap and its page cache.
850 static int shmem_free_swap(struct address_space *mapping,
851 pgoff_t index, void *radswap)
855 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
858 free_swap_and_cache(radix_to_swp_entry(radswap));
863 * Determine (in bytes) how many of the shmem object's pages mapped by the
864 * given offsets are swapped out.
866 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
867 * as long as the inode doesn't go away and racy results are not a problem.
869 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
870 pgoff_t start, pgoff_t end)
872 XA_STATE(xas, &mapping->i_pages, start);
874 unsigned long swapped = 0;
875 unsigned long max = end - 1;
878 xas_for_each(&xas, page, max) {
879 if (xas_retry(&xas, page))
881 if (xa_is_value(page))
883 if (xas.xa_index == max)
885 if (need_resched()) {
893 return swapped << PAGE_SHIFT;
897 * Determine (in bytes) how many of the shmem object's pages mapped by the
898 * given vma is swapped out.
900 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
901 * as long as the inode doesn't go away and racy results are not a problem.
903 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
905 struct inode *inode = file_inode(vma->vm_file);
906 struct shmem_inode_info *info = SHMEM_I(inode);
907 struct address_space *mapping = inode->i_mapping;
908 unsigned long swapped;
910 /* Be careful as we don't hold info->lock */
911 swapped = READ_ONCE(info->swapped);
914 * The easier cases are when the shmem object has nothing in swap, or
915 * the vma maps it whole. Then we can simply use the stats that we
921 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
922 return swapped << PAGE_SHIFT;
924 /* Here comes the more involved part */
925 return shmem_partial_swap_usage(mapping, vma->vm_pgoff,
926 vma->vm_pgoff + vma_pages(vma));
930 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
932 void shmem_unlock_mapping(struct address_space *mapping)
934 struct folio_batch fbatch;
937 folio_batch_init(&fbatch);
939 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
941 while (!mapping_unevictable(mapping) &&
942 filemap_get_folios(mapping, &index, ~0UL, &fbatch)) {
943 check_move_unevictable_folios(&fbatch);
944 folio_batch_release(&fbatch);
949 static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
954 * At first avoid shmem_get_folio(,,,SGP_READ): that fails
955 * beyond i_size, and reports fallocated folios as holes.
957 folio = filemap_get_entry(inode->i_mapping, index);
960 if (!xa_is_value(folio)) {
962 if (folio->mapping == inode->i_mapping)
964 /* The folio has been swapped out */
969 * But read a folio back from swap if any of it is within i_size
970 * (although in some cases this is just a waste of time).
973 shmem_get_folio(inode, index, &folio, SGP_READ);
978 * Remove range of pages and swap entries from page cache, and free them.
979 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
981 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
984 struct address_space *mapping = inode->i_mapping;
985 struct shmem_inode_info *info = SHMEM_I(inode);
986 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
987 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
988 struct folio_batch fbatch;
989 pgoff_t indices[PAGEVEC_SIZE];
992 long nr_swaps_freed = 0;
997 end = -1; /* unsigned, so actually very big */
999 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
1000 info->fallocend = start;
1002 folio_batch_init(&fbatch);
1004 while (index < end && find_lock_entries(mapping, &index, end - 1,
1005 &fbatch, indices)) {
1006 for (i = 0; i < folio_batch_count(&fbatch); i++) {
1007 folio = fbatch.folios[i];
1009 if (xa_is_value(folio)) {
1012 nr_swaps_freed += !shmem_free_swap(mapping,
1017 if (!unfalloc || !folio_test_uptodate(folio))
1018 truncate_inode_folio(mapping, folio);
1019 folio_unlock(folio);
1021 folio_batch_remove_exceptionals(&fbatch);
1022 folio_batch_release(&fbatch);
1027 * When undoing a failed fallocate, we want none of the partial folio
1028 * zeroing and splitting below, but shall want to truncate the whole
1029 * folio when !uptodate indicates that it was added by this fallocate,
1030 * even when [lstart, lend] covers only a part of the folio.
1035 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
1036 folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT);
1038 same_folio = lend < folio_pos(folio) + folio_size(folio);
1039 folio_mark_dirty(folio);
1040 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
1041 start = folio_next_index(folio);
1045 folio_unlock(folio);
1051 folio = shmem_get_partial_folio(inode, lend >> PAGE_SHIFT);
1053 folio_mark_dirty(folio);
1054 if (!truncate_inode_partial_folio(folio, lstart, lend))
1056 folio_unlock(folio);
1063 while (index < end) {
1066 if (!find_get_entries(mapping, &index, end - 1, &fbatch,
1068 /* If all gone or hole-punch or unfalloc, we're done */
1069 if (index == start || end != -1)
1071 /* But if truncating, restart to make sure all gone */
1075 for (i = 0; i < folio_batch_count(&fbatch); i++) {
1076 folio = fbatch.folios[i];
1078 if (xa_is_value(folio)) {
1081 if (shmem_free_swap(mapping, indices[i], folio)) {
1082 /* Swap was replaced by page: retry */
1092 if (!unfalloc || !folio_test_uptodate(folio)) {
1093 if (folio_mapping(folio) != mapping) {
1094 /* Page was replaced by swap: retry */
1095 folio_unlock(folio);
1099 VM_BUG_ON_FOLIO(folio_test_writeback(folio),
1102 if (!folio_test_large(folio)) {
1103 truncate_inode_folio(mapping, folio);
1104 } else if (truncate_inode_partial_folio(folio, lstart, lend)) {
1106 * If we split a page, reset the loop so
1107 * that we pick up the new sub pages.
1108 * Otherwise the THP was entirely
1109 * dropped or the target range was
1110 * zeroed, so just continue the loop as
1113 if (!folio_test_large(folio)) {
1114 folio_unlock(folio);
1120 folio_unlock(folio);
1122 folio_batch_remove_exceptionals(&fbatch);
1123 folio_batch_release(&fbatch);
1126 shmem_recalc_inode(inode, 0, -nr_swaps_freed);
1129 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1131 shmem_undo_range(inode, lstart, lend, false);
1132 inode->i_mtime = inode_set_ctime_current(inode);
1133 inode_inc_iversion(inode);
1135 EXPORT_SYMBOL_GPL(shmem_truncate_range);
1137 static int shmem_getattr(struct mnt_idmap *idmap,
1138 const struct path *path, struct kstat *stat,
1139 u32 request_mask, unsigned int query_flags)
1141 struct inode *inode = path->dentry->d_inode;
1142 struct shmem_inode_info *info = SHMEM_I(inode);
1144 if (info->alloced - info->swapped != inode->i_mapping->nrpages)
1145 shmem_recalc_inode(inode, 0, 0);
1147 if (info->fsflags & FS_APPEND_FL)
1148 stat->attributes |= STATX_ATTR_APPEND;
1149 if (info->fsflags & FS_IMMUTABLE_FL)
1150 stat->attributes |= STATX_ATTR_IMMUTABLE;
1151 if (info->fsflags & FS_NODUMP_FL)
1152 stat->attributes |= STATX_ATTR_NODUMP;
1153 stat->attributes_mask |= (STATX_ATTR_APPEND |
1154 STATX_ATTR_IMMUTABLE |
1156 generic_fillattr(idmap, request_mask, inode, stat);
1158 if (shmem_is_huge(inode, 0, false, NULL, 0))
1159 stat->blksize = HPAGE_PMD_SIZE;
1161 if (request_mask & STATX_BTIME) {
1162 stat->result_mask |= STATX_BTIME;
1163 stat->btime.tv_sec = info->i_crtime.tv_sec;
1164 stat->btime.tv_nsec = info->i_crtime.tv_nsec;
1170 static int shmem_setattr(struct mnt_idmap *idmap,
1171 struct dentry *dentry, struct iattr *attr)
1173 struct inode *inode = d_inode(dentry);
1174 struct shmem_inode_info *info = SHMEM_I(inode);
1176 bool update_mtime = false;
1177 bool update_ctime = true;
1179 error = setattr_prepare(idmap, dentry, attr);
1183 if ((info->seals & F_SEAL_EXEC) && (attr->ia_valid & ATTR_MODE)) {
1184 if ((inode->i_mode ^ attr->ia_mode) & 0111) {
1189 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1190 loff_t oldsize = inode->i_size;
1191 loff_t newsize = attr->ia_size;
1193 /* protected by i_rwsem */
1194 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1195 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1198 if (newsize != oldsize) {
1199 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1203 i_size_write(inode, newsize);
1204 update_mtime = true;
1206 update_ctime = false;
1208 if (newsize <= oldsize) {
1209 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1210 if (oldsize > holebegin)
1211 unmap_mapping_range(inode->i_mapping,
1214 shmem_truncate_range(inode,
1215 newsize, (loff_t)-1);
1216 /* unmap again to remove racily COWed private pages */
1217 if (oldsize > holebegin)
1218 unmap_mapping_range(inode->i_mapping,
1223 if (is_quota_modification(idmap, inode, attr)) {
1224 error = dquot_initialize(inode);
1229 /* Transfer quota accounting */
1230 if (i_uid_needs_update(idmap, attr, inode) ||
1231 i_gid_needs_update(idmap, attr, inode)) {
1232 error = dquot_transfer(idmap, inode, attr);
1238 setattr_copy(idmap, inode, attr);
1239 if (attr->ia_valid & ATTR_MODE)
1240 error = posix_acl_chmod(idmap, dentry, inode->i_mode);
1241 if (!error && update_ctime) {
1242 inode_set_ctime_current(inode);
1244 inode->i_mtime = inode_get_ctime(inode);
1245 inode_inc_iversion(inode);
1250 static void shmem_evict_inode(struct inode *inode)
1252 struct shmem_inode_info *info = SHMEM_I(inode);
1253 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1256 if (shmem_mapping(inode->i_mapping)) {
1257 shmem_unacct_size(info->flags, inode->i_size);
1259 mapping_set_exiting(inode->i_mapping);
1260 shmem_truncate_range(inode, 0, (loff_t)-1);
1261 if (!list_empty(&info->shrinklist)) {
1262 spin_lock(&sbinfo->shrinklist_lock);
1263 if (!list_empty(&info->shrinklist)) {
1264 list_del_init(&info->shrinklist);
1265 sbinfo->shrinklist_len--;
1267 spin_unlock(&sbinfo->shrinklist_lock);
1269 while (!list_empty(&info->swaplist)) {
1270 /* Wait while shmem_unuse() is scanning this inode... */
1271 wait_var_event(&info->stop_eviction,
1272 !atomic_read(&info->stop_eviction));
1273 mutex_lock(&shmem_swaplist_mutex);
1274 /* ...but beware of the race if we peeked too early */
1275 if (!atomic_read(&info->stop_eviction))
1276 list_del_init(&info->swaplist);
1277 mutex_unlock(&shmem_swaplist_mutex);
1281 simple_xattrs_free(&info->xattrs, sbinfo->max_inodes ? &freed : NULL);
1282 shmem_free_inode(inode->i_sb, freed);
1283 WARN_ON(inode->i_blocks);
1285 #ifdef CONFIG_TMPFS_QUOTA
1286 dquot_free_inode(inode);
1291 static int shmem_find_swap_entries(struct address_space *mapping,
1292 pgoff_t start, struct folio_batch *fbatch,
1293 pgoff_t *indices, unsigned int type)
1295 XA_STATE(xas, &mapping->i_pages, start);
1296 struct folio *folio;
1300 xas_for_each(&xas, folio, ULONG_MAX) {
1301 if (xas_retry(&xas, folio))
1304 if (!xa_is_value(folio))
1307 entry = radix_to_swp_entry(folio);
1309 * swapin error entries can be found in the mapping. But they're
1310 * deliberately ignored here as we've done everything we can do.
1312 if (swp_type(entry) != type)
1315 indices[folio_batch_count(fbatch)] = xas.xa_index;
1316 if (!folio_batch_add(fbatch, folio))
1319 if (need_resched()) {
1326 return xas.xa_index;
1330 * Move the swapped pages for an inode to page cache. Returns the count
1331 * of pages swapped in, or the error in case of failure.
1333 static int shmem_unuse_swap_entries(struct inode *inode,
1334 struct folio_batch *fbatch, pgoff_t *indices)
1339 struct address_space *mapping = inode->i_mapping;
1341 for (i = 0; i < folio_batch_count(fbatch); i++) {
1342 struct folio *folio = fbatch->folios[i];
1344 if (!xa_is_value(folio))
1346 error = shmem_swapin_folio(inode, indices[i],
1348 mapping_gfp_mask(mapping),
1351 folio_unlock(folio);
1355 if (error == -ENOMEM)
1359 return error ? error : ret;
1363 * If swap found in inode, free it and move page from swapcache to filecache.
1365 static int shmem_unuse_inode(struct inode *inode, unsigned int type)
1367 struct address_space *mapping = inode->i_mapping;
1369 struct folio_batch fbatch;
1370 pgoff_t indices[PAGEVEC_SIZE];
1374 folio_batch_init(&fbatch);
1375 shmem_find_swap_entries(mapping, start, &fbatch, indices, type);
1376 if (folio_batch_count(&fbatch) == 0) {
1381 ret = shmem_unuse_swap_entries(inode, &fbatch, indices);
1385 start = indices[folio_batch_count(&fbatch) - 1];
1392 * Read all the shared memory data that resides in the swap
1393 * device 'type' back into memory, so the swap device can be
1396 int shmem_unuse(unsigned int type)
1398 struct shmem_inode_info *info, *next;
1401 if (list_empty(&shmem_swaplist))
1404 mutex_lock(&shmem_swaplist_mutex);
1405 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1406 if (!info->swapped) {
1407 list_del_init(&info->swaplist);
1411 * Drop the swaplist mutex while searching the inode for swap;
1412 * but before doing so, make sure shmem_evict_inode() will not
1413 * remove placeholder inode from swaplist, nor let it be freed
1414 * (igrab() would protect from unlink, but not from unmount).
1416 atomic_inc(&info->stop_eviction);
1417 mutex_unlock(&shmem_swaplist_mutex);
1419 error = shmem_unuse_inode(&info->vfs_inode, type);
1422 mutex_lock(&shmem_swaplist_mutex);
1423 next = list_next_entry(info, swaplist);
1425 list_del_init(&info->swaplist);
1426 if (atomic_dec_and_test(&info->stop_eviction))
1427 wake_up_var(&info->stop_eviction);
1431 mutex_unlock(&shmem_swaplist_mutex);
1437 * Move the page from the page cache to the swap cache.
1439 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1441 struct folio *folio = page_folio(page);
1442 struct address_space *mapping = folio->mapping;
1443 struct inode *inode = mapping->host;
1444 struct shmem_inode_info *info = SHMEM_I(inode);
1445 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1450 * Our capabilities prevent regular writeback or sync from ever calling
1451 * shmem_writepage; but a stacking filesystem might use ->writepage of
1452 * its underlying filesystem, in which case tmpfs should write out to
1453 * swap only in response to memory pressure, and not for the writeback
1456 if (WARN_ON_ONCE(!wbc->for_reclaim))
1459 if (WARN_ON_ONCE((info->flags & VM_LOCKED) || sbinfo->noswap))
1462 if (!total_swap_pages)
1466 * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or
1467 * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
1468 * and its shmem_writeback() needs them to be split when swapping.
1470 if (folio_test_large(folio)) {
1471 /* Ensure the subpages are still dirty */
1472 folio_test_set_dirty(folio);
1473 if (split_huge_page(page) < 0)
1475 folio = page_folio(page);
1476 folio_clear_dirty(folio);
1479 index = folio->index;
1482 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1483 * value into swapfile.c, the only way we can correctly account for a
1484 * fallocated folio arriving here is now to initialize it and write it.
1486 * That's okay for a folio already fallocated earlier, but if we have
1487 * not yet completed the fallocation, then (a) we want to keep track
1488 * of this folio in case we have to undo it, and (b) it may not be a
1489 * good idea to continue anyway, once we're pushing into swap. So
1490 * reactivate the folio, and let shmem_fallocate() quit when too many.
1492 if (!folio_test_uptodate(folio)) {
1493 if (inode->i_private) {
1494 struct shmem_falloc *shmem_falloc;
1495 spin_lock(&inode->i_lock);
1496 shmem_falloc = inode->i_private;
1498 !shmem_falloc->waitq &&
1499 index >= shmem_falloc->start &&
1500 index < shmem_falloc->next)
1501 shmem_falloc->nr_unswapped++;
1503 shmem_falloc = NULL;
1504 spin_unlock(&inode->i_lock);
1508 folio_zero_range(folio, 0, folio_size(folio));
1509 flush_dcache_folio(folio);
1510 folio_mark_uptodate(folio);
1513 swap = folio_alloc_swap(folio);
1518 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1519 * if it's not already there. Do it now before the folio is
1520 * moved to swap cache, when its pagelock no longer protects
1521 * the inode from eviction. But don't unlock the mutex until
1522 * we've incremented swapped, because shmem_unuse_inode() will
1523 * prune a !swapped inode from the swaplist under this mutex.
1525 mutex_lock(&shmem_swaplist_mutex);
1526 if (list_empty(&info->swaplist))
1527 list_add(&info->swaplist, &shmem_swaplist);
1529 if (add_to_swap_cache(folio, swap,
1530 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1532 shmem_recalc_inode(inode, 0, 1);
1533 swap_shmem_alloc(swap);
1534 shmem_delete_from_page_cache(folio, swp_to_radix_entry(swap));
1536 mutex_unlock(&shmem_swaplist_mutex);
1537 BUG_ON(folio_mapped(folio));
1538 swap_writepage(&folio->page, wbc);
1542 mutex_unlock(&shmem_swaplist_mutex);
1543 put_swap_folio(folio, swap);
1545 folio_mark_dirty(folio);
1546 if (wbc->for_reclaim)
1547 return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */
1548 folio_unlock(folio);
1552 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1553 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1557 if (!mpol || mpol->mode == MPOL_DEFAULT)
1558 return; /* show nothing */
1560 mpol_to_str(buffer, sizeof(buffer), mpol);
1562 seq_printf(seq, ",mpol=%s", buffer);
1565 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1567 struct mempolicy *mpol = NULL;
1569 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1570 mpol = sbinfo->mpol;
1572 raw_spin_unlock(&sbinfo->stat_lock);
1576 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1577 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1580 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1584 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1586 #define vm_policy vm_private_data
1589 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1590 struct shmem_inode_info *info, pgoff_t index)
1592 /* Create a pseudo vma that just contains the policy */
1593 vma_init(vma, NULL);
1594 /* Bias interleave by inode number to distribute better across nodes */
1595 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1596 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1599 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1601 /* Drop reference taken by mpol_shared_policy_lookup() */
1602 mpol_cond_put(vma->vm_policy);
1605 static struct folio *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1606 struct shmem_inode_info *info, pgoff_t index)
1608 struct vm_area_struct pvma;
1610 struct vm_fault vmf = {
1614 shmem_pseudo_vma_init(&pvma, info, index);
1615 page = swap_cluster_readahead(swap, gfp, &vmf);
1616 shmem_pseudo_vma_destroy(&pvma);
1620 return page_folio(page);
1624 * Make sure huge_gfp is always more limited than limit_gfp.
1625 * Some of the flags set permissions, while others set limitations.
1627 static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1629 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1630 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1631 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1632 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1634 /* Allow allocations only from the originally specified zones. */
1635 result |= zoneflags;
1638 * Minimize the result gfp by taking the union with the deny flags,
1639 * and the intersection of the allow flags.
1641 result |= (limit_gfp & denyflags);
1642 result |= (huge_gfp & limit_gfp) & allowflags;
1647 static struct folio *shmem_alloc_hugefolio(gfp_t gfp,
1648 struct shmem_inode_info *info, pgoff_t index)
1650 struct vm_area_struct pvma;
1651 struct address_space *mapping = info->vfs_inode.i_mapping;
1653 struct folio *folio;
1655 hindex = round_down(index, HPAGE_PMD_NR);
1656 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1660 shmem_pseudo_vma_init(&pvma, info, hindex);
1661 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, &pvma, 0, true);
1662 shmem_pseudo_vma_destroy(&pvma);
1664 count_vm_event(THP_FILE_FALLBACK);
1668 static struct folio *shmem_alloc_folio(gfp_t gfp,
1669 struct shmem_inode_info *info, pgoff_t index)
1671 struct vm_area_struct pvma;
1672 struct folio *folio;
1674 shmem_pseudo_vma_init(&pvma, info, index);
1675 folio = vma_alloc_folio(gfp, 0, &pvma, 0, false);
1676 shmem_pseudo_vma_destroy(&pvma);
1681 static struct folio *shmem_alloc_and_acct_folio(gfp_t gfp, struct inode *inode,
1682 pgoff_t index, bool huge)
1684 struct shmem_inode_info *info = SHMEM_I(inode);
1685 struct folio *folio;
1689 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1691 nr = huge ? HPAGE_PMD_NR : 1;
1693 err = shmem_inode_acct_block(inode, nr);
1698 folio = shmem_alloc_hugefolio(gfp, info, index);
1700 folio = shmem_alloc_folio(gfp, info, index);
1702 __folio_set_locked(folio);
1703 __folio_set_swapbacked(folio);
1708 shmem_inode_unacct_blocks(inode, nr);
1710 return ERR_PTR(err);
1714 * When a page is moved from swapcache to shmem filecache (either by the
1715 * usual swapin of shmem_get_folio_gfp(), or by the less common swapoff of
1716 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1717 * ignorance of the mapping it belongs to. If that mapping has special
1718 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1719 * we may need to copy to a suitable page before moving to filecache.
1721 * In a future release, this may well be extended to respect cpuset and
1722 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1723 * but for now it is a simple matter of zone.
1725 static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
1727 return folio_zonenum(folio) > gfp_zone(gfp);
1730 static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
1731 struct shmem_inode_info *info, pgoff_t index)
1733 struct folio *old, *new;
1734 struct address_space *swap_mapping;
1741 swap_index = swp_offset(entry);
1742 swap_mapping = swap_address_space(entry);
1745 * We have arrived here because our zones are constrained, so don't
1746 * limit chance of success by further cpuset and node constraints.
1748 gfp &= ~GFP_CONSTRAINT_MASK;
1749 VM_BUG_ON_FOLIO(folio_test_large(old), old);
1750 new = shmem_alloc_folio(gfp, info, index);
1755 folio_copy(new, old);
1756 flush_dcache_folio(new);
1758 __folio_set_locked(new);
1759 __folio_set_swapbacked(new);
1760 folio_mark_uptodate(new);
1762 folio_set_swapcache(new);
1765 * Our caller will very soon move newpage out of swapcache, but it's
1766 * a nice clean interface for us to replace oldpage by newpage there.
1768 xa_lock_irq(&swap_mapping->i_pages);
1769 error = shmem_replace_entry(swap_mapping, swap_index, old, new);
1771 mem_cgroup_migrate(old, new);
1772 __lruvec_stat_mod_folio(new, NR_FILE_PAGES, 1);
1773 __lruvec_stat_mod_folio(new, NR_SHMEM, 1);
1774 __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -1);
1775 __lruvec_stat_mod_folio(old, NR_SHMEM, -1);
1777 xa_unlock_irq(&swap_mapping->i_pages);
1779 if (unlikely(error)) {
1781 * Is this possible? I think not, now that our callers check
1782 * both PageSwapCache and page_private after getting page lock;
1783 * but be defensive. Reverse old to newpage for clear and free.
1791 folio_clear_swapcache(old);
1792 old->private = NULL;
1795 folio_put_refs(old, 2);
1799 static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
1800 struct folio *folio, swp_entry_t swap)
1802 struct address_space *mapping = inode->i_mapping;
1803 swp_entry_t swapin_error;
1806 swapin_error = make_poisoned_swp_entry();
1807 old = xa_cmpxchg_irq(&mapping->i_pages, index,
1808 swp_to_radix_entry(swap),
1809 swp_to_radix_entry(swapin_error), 0);
1810 if (old != swp_to_radix_entry(swap))
1813 folio_wait_writeback(folio);
1814 delete_from_swap_cache(folio);
1816 * Don't treat swapin error folio as alloced. Otherwise inode->i_blocks
1817 * won't be 0 when inode is released and thus trigger WARN_ON(i_blocks)
1818 * in shmem_evict_inode().
1820 shmem_recalc_inode(inode, -1, -1);
1825 * Swap in the folio pointed to by *foliop.
1826 * Caller has to make sure that *foliop contains a valid swapped folio.
1827 * Returns 0 and the folio in foliop if success. On failure, returns the
1828 * error code and NULL in *foliop.
1830 static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
1831 struct folio **foliop, enum sgp_type sgp,
1832 gfp_t gfp, struct vm_area_struct *vma,
1833 vm_fault_t *fault_type)
1835 struct address_space *mapping = inode->i_mapping;
1836 struct shmem_inode_info *info = SHMEM_I(inode);
1837 struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
1838 struct swap_info_struct *si;
1839 struct folio *folio = NULL;
1843 VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
1844 swap = radix_to_swp_entry(*foliop);
1847 if (is_poisoned_swp_entry(swap))
1850 si = get_swap_device(swap);
1852 if (!shmem_confirm_swap(mapping, index, swap))
1858 /* Look it up and read it in.. */
1859 folio = swap_cache_get_folio(swap, NULL, 0);
1861 /* Or update major stats only when swapin succeeds?? */
1863 *fault_type |= VM_FAULT_MAJOR;
1864 count_vm_event(PGMAJFAULT);
1865 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1867 /* Here we actually start the io */
1868 folio = shmem_swapin(swap, gfp, info, index);
1875 /* We have to do this with folio locked to prevent races */
1877 if (!folio_test_swapcache(folio) ||
1878 folio->swap.val != swap.val ||
1879 !shmem_confirm_swap(mapping, index, swap)) {
1883 if (!folio_test_uptodate(folio)) {
1887 folio_wait_writeback(folio);
1890 * Some architectures may have to restore extra metadata to the
1891 * folio after reading from swap.
1893 arch_swap_restore(swap, folio);
1895 if (shmem_should_replace_folio(folio, gfp)) {
1896 error = shmem_replace_folio(&folio, gfp, info, index);
1901 error = shmem_add_to_page_cache(folio, mapping, index,
1902 swp_to_radix_entry(swap), gfp,
1907 shmem_recalc_inode(inode, 0, -1);
1909 if (sgp == SGP_WRITE)
1910 folio_mark_accessed(folio);
1912 delete_from_swap_cache(folio);
1913 folio_mark_dirty(folio);
1915 put_swap_device(si);
1920 if (!shmem_confirm_swap(mapping, index, swap))
1923 shmem_set_folio_swapin_error(inode, index, folio, swap);
1926 folio_unlock(folio);
1929 put_swap_device(si);
1935 * shmem_get_folio_gfp - find page in cache, or get from swap, or allocate
1937 * If we allocate a new one we do not mark it dirty. That's up to the
1938 * vm. If we swap it in we mark it dirty since we also free the swap
1939 * entry since a page cannot live in both the swap and page cache.
1941 * vma, vmf, and fault_type are only supplied by shmem_fault:
1942 * otherwise they are NULL.
1944 static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
1945 struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
1946 struct vm_area_struct *vma, struct vm_fault *vmf,
1947 vm_fault_t *fault_type)
1949 struct address_space *mapping = inode->i_mapping;
1950 struct shmem_inode_info *info = SHMEM_I(inode);
1951 struct shmem_sb_info *sbinfo;
1952 struct mm_struct *charge_mm;
1953 struct folio *folio;
1960 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1963 if (sgp <= SGP_CACHE &&
1964 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1968 sbinfo = SHMEM_SB(inode->i_sb);
1969 charge_mm = vma ? vma->vm_mm : NULL;
1971 folio = filemap_get_entry(mapping, index);
1972 if (folio && vma && userfaultfd_minor(vma)) {
1973 if (!xa_is_value(folio))
1975 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
1979 if (xa_is_value(folio)) {
1980 error = shmem_swapin_folio(inode, index, &folio,
1981 sgp, gfp, vma, fault_type);
1982 if (error == -EEXIST)
1992 /* Has the folio been truncated or swapped out? */
1993 if (unlikely(folio->mapping != mapping)) {
1994 folio_unlock(folio);
1998 if (sgp == SGP_WRITE)
1999 folio_mark_accessed(folio);
2000 if (folio_test_uptodate(folio))
2002 /* fallocated folio */
2003 if (sgp != SGP_READ)
2005 folio_unlock(folio);
2010 * SGP_READ: succeed on hole, with NULL folio, letting caller zero.
2011 * SGP_NOALLOC: fail on hole, with NULL folio, letting caller fail.
2014 if (sgp == SGP_READ)
2016 if (sgp == SGP_NOALLOC)
2020 * Fast cache lookup and swap lookup did not find it: allocate.
2023 if (vma && userfaultfd_missing(vma)) {
2024 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
2028 if (!shmem_is_huge(inode, index, false,
2029 vma ? vma->vm_mm : NULL, vma ? vma->vm_flags : 0))
2032 huge_gfp = vma_thp_gfp_mask(vma);
2033 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
2034 folio = shmem_alloc_and_acct_folio(huge_gfp, inode, index, true);
2035 if (IS_ERR(folio)) {
2037 folio = shmem_alloc_and_acct_folio(gfp, inode, index, false);
2039 if (IS_ERR(folio)) {
2042 error = PTR_ERR(folio);
2044 if (error != -ENOSPC)
2047 * Try to reclaim some space by splitting a large folio
2048 * beyond i_size on the filesystem.
2053 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
2054 if (ret == SHRINK_STOP)
2062 hindex = round_down(index, folio_nr_pages(folio));
2064 if (sgp == SGP_WRITE)
2065 __folio_set_referenced(folio);
2067 error = shmem_add_to_page_cache(folio, mapping, hindex,
2068 NULL, gfp & GFP_RECLAIM_MASK,
2073 folio_add_lru(folio);
2074 shmem_recalc_inode(inode, folio_nr_pages(folio), 0);
2077 if (folio_test_pmd_mappable(folio) &&
2078 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
2079 folio_next_index(folio) - 1) {
2081 * Part of the large folio is beyond i_size: subject
2082 * to shrink under memory pressure.
2084 spin_lock(&sbinfo->shrinklist_lock);
2086 * _careful to defend against unlocked access to
2087 * ->shrink_list in shmem_unused_huge_shrink()
2089 if (list_empty_careful(&info->shrinklist)) {
2090 list_add_tail(&info->shrinklist,
2091 &sbinfo->shrinklist);
2092 sbinfo->shrinklist_len++;
2094 spin_unlock(&sbinfo->shrinklist_lock);
2098 * Let SGP_FALLOC use the SGP_WRITE optimization on a new folio.
2100 if (sgp == SGP_FALLOC)
2104 * Let SGP_WRITE caller clear ends if write does not fill folio;
2105 * but SGP_FALLOC on a folio fallocated earlier must initialize
2106 * it now, lest undo on failure cancel our earlier guarantee.
2108 if (sgp != SGP_WRITE && !folio_test_uptodate(folio)) {
2109 long i, n = folio_nr_pages(folio);
2111 for (i = 0; i < n; i++)
2112 clear_highpage(folio_page(folio, i));
2113 flush_dcache_folio(folio);
2114 folio_mark_uptodate(folio);
2117 /* Perhaps the file has been truncated since we checked */
2118 if (sgp <= SGP_CACHE &&
2119 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
2121 folio_clear_dirty(folio);
2122 filemap_remove_folio(folio);
2123 shmem_recalc_inode(inode, 0, 0);
2136 shmem_inode_unacct_blocks(inode, folio_nr_pages(folio));
2138 if (folio_test_large(folio)) {
2139 folio_unlock(folio);
2145 folio_unlock(folio);
2148 if (error == -ENOSPC && !once++) {
2149 shmem_recalc_inode(inode, 0, 0);
2152 if (error == -EEXIST)
2157 int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
2160 return shmem_get_folio_gfp(inode, index, foliop, sgp,
2161 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
2165 * This is like autoremove_wake_function, but it removes the wait queue
2166 * entry unconditionally - even if something else had already woken the
2169 static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
2171 int ret = default_wake_function(wait, mode, sync, key);
2172 list_del_init(&wait->entry);
2176 static vm_fault_t shmem_fault(struct vm_fault *vmf)
2178 struct vm_area_struct *vma = vmf->vma;
2179 struct inode *inode = file_inode(vma->vm_file);
2180 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2181 struct folio *folio = NULL;
2183 vm_fault_t ret = VM_FAULT_LOCKED;
2186 * Trinity finds that probing a hole which tmpfs is punching can
2187 * prevent the hole-punch from ever completing: which in turn
2188 * locks writers out with its hold on i_rwsem. So refrain from
2189 * faulting pages into the hole while it's being punched. Although
2190 * shmem_undo_range() does remove the additions, it may be unable to
2191 * keep up, as each new page needs its own unmap_mapping_range() call,
2192 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2194 * It does not matter if we sometimes reach this check just before the
2195 * hole-punch begins, so that one fault then races with the punch:
2196 * we just need to make racing faults a rare case.
2198 * The implementation below would be much simpler if we just used a
2199 * standard mutex or completion: but we cannot take i_rwsem in fault,
2200 * and bloating every shmem inode for this unlikely case would be sad.
2202 if (unlikely(inode->i_private)) {
2203 struct shmem_falloc *shmem_falloc;
2205 spin_lock(&inode->i_lock);
2206 shmem_falloc = inode->i_private;
2208 shmem_falloc->waitq &&
2209 vmf->pgoff >= shmem_falloc->start &&
2210 vmf->pgoff < shmem_falloc->next) {
2212 wait_queue_head_t *shmem_falloc_waitq;
2213 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2215 ret = VM_FAULT_NOPAGE;
2216 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2218 ret = VM_FAULT_RETRY;
2220 shmem_falloc_waitq = shmem_falloc->waitq;
2221 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2222 TASK_UNINTERRUPTIBLE);
2223 spin_unlock(&inode->i_lock);
2227 * shmem_falloc_waitq points into the shmem_fallocate()
2228 * stack of the hole-punching task: shmem_falloc_waitq
2229 * is usually invalid by the time we reach here, but
2230 * finish_wait() does not dereference it in that case;
2231 * though i_lock needed lest racing with wake_up_all().
2233 spin_lock(&inode->i_lock);
2234 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2235 spin_unlock(&inode->i_lock);
2241 spin_unlock(&inode->i_lock);
2244 err = shmem_get_folio_gfp(inode, vmf->pgoff, &folio, SGP_CACHE,
2245 gfp, vma, vmf, &ret);
2247 return vmf_error(err);
2249 vmf->page = folio_file_page(folio, vmf->pgoff);
2253 unsigned long shmem_get_unmapped_area(struct file *file,
2254 unsigned long uaddr, unsigned long len,
2255 unsigned long pgoff, unsigned long flags)
2257 unsigned long (*get_area)(struct file *,
2258 unsigned long, unsigned long, unsigned long, unsigned long);
2260 unsigned long offset;
2261 unsigned long inflated_len;
2262 unsigned long inflated_addr;
2263 unsigned long inflated_offset;
2265 if (len > TASK_SIZE)
2268 get_area = current->mm->get_unmapped_area;
2269 addr = get_area(file, uaddr, len, pgoff, flags);
2271 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2273 if (IS_ERR_VALUE(addr))
2275 if (addr & ~PAGE_MASK)
2277 if (addr > TASK_SIZE - len)
2280 if (shmem_huge == SHMEM_HUGE_DENY)
2282 if (len < HPAGE_PMD_SIZE)
2284 if (flags & MAP_FIXED)
2287 * Our priority is to support MAP_SHARED mapped hugely;
2288 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2289 * But if caller specified an address hint and we allocated area there
2290 * successfully, respect that as before.
2295 if (shmem_huge != SHMEM_HUGE_FORCE) {
2296 struct super_block *sb;
2299 VM_BUG_ON(file->f_op != &shmem_file_operations);
2300 sb = file_inode(file)->i_sb;
2303 * Called directly from mm/mmap.c, or drivers/char/mem.c
2304 * for "/dev/zero", to create a shared anonymous object.
2306 if (IS_ERR(shm_mnt))
2308 sb = shm_mnt->mnt_sb;
2310 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2314 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2315 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2317 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2320 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2321 if (inflated_len > TASK_SIZE)
2323 if (inflated_len < len)
2326 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2327 if (IS_ERR_VALUE(inflated_addr))
2329 if (inflated_addr & ~PAGE_MASK)
2332 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2333 inflated_addr += offset - inflated_offset;
2334 if (inflated_offset > offset)
2335 inflated_addr += HPAGE_PMD_SIZE;
2337 if (inflated_addr > TASK_SIZE - len)
2339 return inflated_addr;
2343 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2345 struct inode *inode = file_inode(vma->vm_file);
2346 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2349 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2352 struct inode *inode = file_inode(vma->vm_file);
2355 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2356 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2360 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2362 struct inode *inode = file_inode(file);
2363 struct shmem_inode_info *info = SHMEM_I(inode);
2364 int retval = -ENOMEM;
2367 * What serializes the accesses to info->flags?
2368 * ipc_lock_object() when called from shmctl_do_lock(),
2369 * no serialization needed when called from shm_destroy().
2371 if (lock && !(info->flags & VM_LOCKED)) {
2372 if (!user_shm_lock(inode->i_size, ucounts))
2374 info->flags |= VM_LOCKED;
2375 mapping_set_unevictable(file->f_mapping);
2377 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2378 user_shm_unlock(inode->i_size, ucounts);
2379 info->flags &= ~VM_LOCKED;
2380 mapping_clear_unevictable(file->f_mapping);
2388 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2390 struct inode *inode = file_inode(file);
2391 struct shmem_inode_info *info = SHMEM_I(inode);
2394 ret = seal_check_future_write(info->seals, vma);
2398 /* arm64 - allow memory tagging on RAM-based files */
2399 vm_flags_set(vma, VM_MTE_ALLOWED);
2401 file_accessed(file);
2402 /* This is anonymous shared memory if it is unlinked at the time of mmap */
2404 vma->vm_ops = &shmem_vm_ops;
2406 vma->vm_ops = &shmem_anon_vm_ops;
2410 static int shmem_file_open(struct inode *inode, struct file *file)
2412 file->f_mode |= FMODE_CAN_ODIRECT;
2413 return generic_file_open(inode, file);
2416 #ifdef CONFIG_TMPFS_XATTR
2417 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2420 * chattr's fsflags are unrelated to extended attributes,
2421 * but tmpfs has chosen to enable them under the same config option.
2423 static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags)
2425 unsigned int i_flags = 0;
2427 if (fsflags & FS_NOATIME_FL)
2428 i_flags |= S_NOATIME;
2429 if (fsflags & FS_APPEND_FL)
2430 i_flags |= S_APPEND;
2431 if (fsflags & FS_IMMUTABLE_FL)
2432 i_flags |= S_IMMUTABLE;
2434 * But FS_NODUMP_FL does not require any action in i_flags.
2436 inode_set_flags(inode, i_flags, S_NOATIME | S_APPEND | S_IMMUTABLE);
2439 static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags)
2442 #define shmem_initxattrs NULL
2445 static struct offset_ctx *shmem_get_offset_ctx(struct inode *inode)
2447 return &SHMEM_I(inode)->dir_offsets;
2450 static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
2451 struct super_block *sb,
2452 struct inode *dir, umode_t mode,
2453 dev_t dev, unsigned long flags)
2455 struct inode *inode;
2456 struct shmem_inode_info *info;
2457 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2461 err = shmem_reserve_inode(sb, &ino);
2463 return ERR_PTR(err);
2466 inode = new_inode(sb);
2468 shmem_free_inode(sb, 0);
2469 return ERR_PTR(-ENOSPC);
2473 inode_init_owner(idmap, inode, dir, mode);
2474 inode->i_blocks = 0;
2475 inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode);
2476 inode->i_generation = get_random_u32();
2477 info = SHMEM_I(inode);
2478 memset(info, 0, (char *)inode - (char *)info);
2479 spin_lock_init(&info->lock);
2480 atomic_set(&info->stop_eviction, 0);
2481 info->seals = F_SEAL_SEAL;
2482 info->flags = flags & VM_NORESERVE;
2483 info->i_crtime = inode->i_mtime;
2484 info->fsflags = (dir == NULL) ? 0 :
2485 SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
2487 shmem_set_inode_flags(inode, info->fsflags);
2488 INIT_LIST_HEAD(&info->shrinklist);
2489 INIT_LIST_HEAD(&info->swaplist);
2490 INIT_LIST_HEAD(&info->swaplist);
2492 mapping_set_unevictable(inode->i_mapping);
2493 simple_xattrs_init(&info->xattrs);
2494 cache_no_acl(inode);
2495 mapping_set_large_folios(inode->i_mapping);
2497 switch (mode & S_IFMT) {
2499 inode->i_op = &shmem_special_inode_operations;
2500 init_special_inode(inode, mode, dev);
2503 inode->i_mapping->a_ops = &shmem_aops;
2504 inode->i_op = &shmem_inode_operations;
2505 inode->i_fop = &shmem_file_operations;
2506 mpol_shared_policy_init(&info->policy,
2507 shmem_get_sbmpol(sbinfo));
2511 /* Some things misbehave if size == 0 on a directory */
2512 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2513 inode->i_op = &shmem_dir_inode_operations;
2514 inode->i_fop = &simple_offset_dir_operations;
2515 simple_offset_init(shmem_get_offset_ctx(inode));
2519 * Must not load anything in the rbtree,
2520 * mpol_free_shared_policy will not be called.
2522 mpol_shared_policy_init(&info->policy, NULL);
2526 lockdep_annotate_inode_mutex_key(inode);
2530 #ifdef CONFIG_TMPFS_QUOTA
2531 static struct inode *shmem_get_inode(struct mnt_idmap *idmap,
2532 struct super_block *sb, struct inode *dir,
2533 umode_t mode, dev_t dev, unsigned long flags)
2536 struct inode *inode;
2538 inode = __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
2542 err = dquot_initialize(inode);
2546 err = dquot_alloc_inode(inode);
2554 inode->i_flags |= S_NOQUOTA;
2556 return ERR_PTR(err);
2559 static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
2560 struct super_block *sb, struct inode *dir,
2561 umode_t mode, dev_t dev, unsigned long flags)
2563 return __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
2565 #endif /* CONFIG_TMPFS_QUOTA */
2567 #ifdef CONFIG_USERFAULTFD
2568 int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
2569 struct vm_area_struct *dst_vma,
2570 unsigned long dst_addr,
2571 unsigned long src_addr,
2573 struct folio **foliop)
2575 struct inode *inode = file_inode(dst_vma->vm_file);
2576 struct shmem_inode_info *info = SHMEM_I(inode);
2577 struct address_space *mapping = inode->i_mapping;
2578 gfp_t gfp = mapping_gfp_mask(mapping);
2579 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2581 struct folio *folio;
2585 if (shmem_inode_acct_block(inode, 1)) {
2587 * We may have got a page, returned -ENOENT triggering a retry,
2588 * and now we find ourselves with -ENOMEM. Release the page, to
2589 * avoid a BUG_ON in our caller.
2591 if (unlikely(*foliop)) {
2600 folio = shmem_alloc_folio(gfp, info, pgoff);
2602 goto out_unacct_blocks;
2604 if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) {
2605 page_kaddr = kmap_local_folio(folio, 0);
2607 * The read mmap_lock is held here. Despite the
2608 * mmap_lock being read recursive a deadlock is still
2609 * possible if a writer has taken a lock. For example:
2611 * process A thread 1 takes read lock on own mmap_lock
2612 * process A thread 2 calls mmap, blocks taking write lock
2613 * process B thread 1 takes page fault, read lock on own mmap lock
2614 * process B thread 2 calls mmap, blocks taking write lock
2615 * process A thread 1 blocks taking read lock on process B
2616 * process B thread 1 blocks taking read lock on process A
2618 * Disable page faults to prevent potential deadlock
2619 * and retry the copy outside the mmap_lock.
2621 pagefault_disable();
2622 ret = copy_from_user(page_kaddr,
2623 (const void __user *)src_addr,
2626 kunmap_local(page_kaddr);
2628 /* fallback to copy_from_user outside mmap_lock */
2629 if (unlikely(ret)) {
2632 /* don't free the page */
2633 goto out_unacct_blocks;
2636 flush_dcache_folio(folio);
2637 } else { /* ZEROPAGE */
2638 clear_user_highpage(&folio->page, dst_addr);
2642 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
2646 VM_BUG_ON(folio_test_locked(folio));
2647 VM_BUG_ON(folio_test_swapbacked(folio));
2648 __folio_set_locked(folio);
2649 __folio_set_swapbacked(folio);
2650 __folio_mark_uptodate(folio);
2653 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2654 if (unlikely(pgoff >= max_off))
2657 ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL,
2658 gfp & GFP_RECLAIM_MASK, dst_vma->vm_mm);
2662 ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
2663 &folio->page, true, flags);
2665 goto out_delete_from_cache;
2667 shmem_recalc_inode(inode, 1, 0);
2668 folio_unlock(folio);
2670 out_delete_from_cache:
2671 filemap_remove_folio(folio);
2673 folio_unlock(folio);
2676 shmem_inode_unacct_blocks(inode, 1);
2679 #endif /* CONFIG_USERFAULTFD */
2682 static const struct inode_operations shmem_symlink_inode_operations;
2683 static const struct inode_operations shmem_short_symlink_operations;
2686 shmem_write_begin(struct file *file, struct address_space *mapping,
2687 loff_t pos, unsigned len,
2688 struct page **pagep, void **fsdata)
2690 struct inode *inode = mapping->host;
2691 struct shmem_inode_info *info = SHMEM_I(inode);
2692 pgoff_t index = pos >> PAGE_SHIFT;
2693 struct folio *folio;
2696 /* i_rwsem is held by caller */
2697 if (unlikely(info->seals & (F_SEAL_GROW |
2698 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2699 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2701 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2705 ret = shmem_get_folio(inode, index, &folio, SGP_WRITE);
2710 *pagep = folio_file_page(folio, index);
2711 if (PageHWPoison(*pagep)) {
2712 folio_unlock(folio);
2722 shmem_write_end(struct file *file, struct address_space *mapping,
2723 loff_t pos, unsigned len, unsigned copied,
2724 struct page *page, void *fsdata)
2726 struct folio *folio = page_folio(page);
2727 struct inode *inode = mapping->host;
2729 if (pos + copied > inode->i_size)
2730 i_size_write(inode, pos + copied);
2732 if (!folio_test_uptodate(folio)) {
2733 if (copied < folio_size(folio)) {
2734 size_t from = offset_in_folio(folio, pos);
2735 folio_zero_segments(folio, 0, from,
2736 from + copied, folio_size(folio));
2738 folio_mark_uptodate(folio);
2740 folio_mark_dirty(folio);
2741 folio_unlock(folio);
2747 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2749 struct file *file = iocb->ki_filp;
2750 struct inode *inode = file_inode(file);
2751 struct address_space *mapping = inode->i_mapping;
2753 unsigned long offset;
2756 loff_t *ppos = &iocb->ki_pos;
2758 index = *ppos >> PAGE_SHIFT;
2759 offset = *ppos & ~PAGE_MASK;
2762 struct folio *folio = NULL;
2763 struct page *page = NULL;
2765 unsigned long nr, ret;
2766 loff_t i_size = i_size_read(inode);
2768 end_index = i_size >> PAGE_SHIFT;
2769 if (index > end_index)
2771 if (index == end_index) {
2772 nr = i_size & ~PAGE_MASK;
2777 error = shmem_get_folio(inode, index, &folio, SGP_READ);
2779 if (error == -EINVAL)
2784 folio_unlock(folio);
2786 page = folio_file_page(folio, index);
2787 if (PageHWPoison(page)) {
2795 * We must evaluate after, since reads (unlike writes)
2796 * are called without i_rwsem protection against truncate
2799 i_size = i_size_read(inode);
2800 end_index = i_size >> PAGE_SHIFT;
2801 if (index == end_index) {
2802 nr = i_size & ~PAGE_MASK;
2813 * If users can be writing to this page using arbitrary
2814 * virtual addresses, take care about potential aliasing
2815 * before reading the page on the kernel side.
2817 if (mapping_writably_mapped(mapping))
2818 flush_dcache_page(page);
2820 * Mark the page accessed if we read the beginning.
2823 folio_mark_accessed(folio);
2825 * Ok, we have the page, and it's up-to-date, so
2826 * now we can copy it to user space...
2828 ret = copy_page_to_iter(page, offset, nr, to);
2831 } else if (user_backed_iter(to)) {
2833 * Copy to user tends to be so well optimized, but
2834 * clear_user() not so much, that it is noticeably
2835 * faster to copy the zero page instead of clearing.
2837 ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to);
2840 * But submitting the same page twice in a row to
2841 * splice() - or others? - can result in confusion:
2842 * so don't attempt that optimization on pipes etc.
2844 ret = iov_iter_zero(nr, to);
2849 index += offset >> PAGE_SHIFT;
2850 offset &= ~PAGE_MASK;
2852 if (!iov_iter_count(to))
2861 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2862 file_accessed(file);
2863 return retval ? retval : error;
2866 static ssize_t shmem_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
2868 struct file *file = iocb->ki_filp;
2869 struct inode *inode = file->f_mapping->host;
2873 ret = generic_write_checks(iocb, from);
2876 ret = file_remove_privs(file);
2879 ret = file_update_time(file);
2882 ret = generic_perform_write(iocb, from);
2884 inode_unlock(inode);
2888 static bool zero_pipe_buf_get(struct pipe_inode_info *pipe,
2889 struct pipe_buffer *buf)
2894 static void zero_pipe_buf_release(struct pipe_inode_info *pipe,
2895 struct pipe_buffer *buf)
2899 static bool zero_pipe_buf_try_steal(struct pipe_inode_info *pipe,
2900 struct pipe_buffer *buf)
2905 static const struct pipe_buf_operations zero_pipe_buf_ops = {
2906 .release = zero_pipe_buf_release,
2907 .try_steal = zero_pipe_buf_try_steal,
2908 .get = zero_pipe_buf_get,
2911 static size_t splice_zeropage_into_pipe(struct pipe_inode_info *pipe,
2912 loff_t fpos, size_t size)
2914 size_t offset = fpos & ~PAGE_MASK;
2916 size = min_t(size_t, size, PAGE_SIZE - offset);
2918 if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
2919 struct pipe_buffer *buf = pipe_head_buf(pipe);
2921 *buf = (struct pipe_buffer) {
2922 .ops = &zero_pipe_buf_ops,
2923 .page = ZERO_PAGE(0),
2933 static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
2934 struct pipe_inode_info *pipe,
2935 size_t len, unsigned int flags)
2937 struct inode *inode = file_inode(in);
2938 struct address_space *mapping = inode->i_mapping;
2939 struct folio *folio = NULL;
2940 size_t total_spliced = 0, used, npages, n, part;
2944 /* Work out how much data we can actually add into the pipe */
2945 used = pipe_occupancy(pipe->head, pipe->tail);
2946 npages = max_t(ssize_t, pipe->max_usage - used, 0);
2947 len = min_t(size_t, len, npages * PAGE_SIZE);
2950 if (*ppos >= i_size_read(inode))
2953 error = shmem_get_folio(inode, *ppos / PAGE_SIZE, &folio,
2956 if (error == -EINVAL)
2961 folio_unlock(folio);
2963 if (folio_test_hwpoison(folio) ||
2964 (folio_test_large(folio) &&
2965 folio_test_has_hwpoisoned(folio))) {
2972 * i_size must be checked after we know the pages are Uptodate.
2974 * Checking i_size after the check allows us to calculate
2975 * the correct value for "nr", which means the zero-filled
2976 * part of the page is not copied back to userspace (unless
2977 * another truncate extends the file - this is desired though).
2979 isize = i_size_read(inode);
2980 if (unlikely(*ppos >= isize))
2982 part = min_t(loff_t, isize - *ppos, len);
2986 * If users can be writing to this page using arbitrary
2987 * virtual addresses, take care about potential aliasing
2988 * before reading the page on the kernel side.
2990 if (mapping_writably_mapped(mapping))
2991 flush_dcache_folio(folio);
2992 folio_mark_accessed(folio);
2994 * Ok, we have the page, and it's up-to-date, so we can
2995 * now splice it into the pipe.
2997 n = splice_folio_into_pipe(pipe, folio, *ppos, part);
3001 n = splice_zeropage_into_pipe(pipe, *ppos, part);
3009 in->f_ra.prev_pos = *ppos;
3010 if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
3020 return total_spliced ? total_spliced : error;
3023 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
3025 struct address_space *mapping = file->f_mapping;
3026 struct inode *inode = mapping->host;
3028 if (whence != SEEK_DATA && whence != SEEK_HOLE)
3029 return generic_file_llseek_size(file, offset, whence,
3030 MAX_LFS_FILESIZE, i_size_read(inode));
3035 /* We're holding i_rwsem so we can access i_size directly */
3036 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
3038 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
3039 inode_unlock(inode);
3043 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
3046 struct inode *inode = file_inode(file);
3047 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3048 struct shmem_inode_info *info = SHMEM_I(inode);
3049 struct shmem_falloc shmem_falloc;
3050 pgoff_t start, index, end, undo_fallocend;
3053 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
3058 if (mode & FALLOC_FL_PUNCH_HOLE) {
3059 struct address_space *mapping = file->f_mapping;
3060 loff_t unmap_start = round_up(offset, PAGE_SIZE);
3061 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
3062 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
3064 /* protected by i_rwsem */
3065 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
3070 shmem_falloc.waitq = &shmem_falloc_waitq;
3071 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
3072 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
3073 spin_lock(&inode->i_lock);
3074 inode->i_private = &shmem_falloc;
3075 spin_unlock(&inode->i_lock);
3077 if ((u64)unmap_end > (u64)unmap_start)
3078 unmap_mapping_range(mapping, unmap_start,
3079 1 + unmap_end - unmap_start, 0);
3080 shmem_truncate_range(inode, offset, offset + len - 1);
3081 /* No need to unmap again: hole-punching leaves COWed pages */
3083 spin_lock(&inode->i_lock);
3084 inode->i_private = NULL;
3085 wake_up_all(&shmem_falloc_waitq);
3086 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
3087 spin_unlock(&inode->i_lock);
3092 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
3093 error = inode_newsize_ok(inode, offset + len);
3097 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
3102 start = offset >> PAGE_SHIFT;
3103 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
3104 /* Try to avoid a swapstorm if len is impossible to satisfy */
3105 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
3110 shmem_falloc.waitq = NULL;
3111 shmem_falloc.start = start;
3112 shmem_falloc.next = start;
3113 shmem_falloc.nr_falloced = 0;
3114 shmem_falloc.nr_unswapped = 0;
3115 spin_lock(&inode->i_lock);
3116 inode->i_private = &shmem_falloc;
3117 spin_unlock(&inode->i_lock);
3120 * info->fallocend is only relevant when huge pages might be
3121 * involved: to prevent split_huge_page() freeing fallocated
3122 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
3124 undo_fallocend = info->fallocend;
3125 if (info->fallocend < end)
3126 info->fallocend = end;
3128 for (index = start; index < end; ) {
3129 struct folio *folio;
3132 * Good, the fallocate(2) manpage permits EINTR: we may have
3133 * been interrupted because we are using up too much memory.
3135 if (signal_pending(current))
3137 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
3140 error = shmem_get_folio(inode, index, &folio,
3143 info->fallocend = undo_fallocend;
3144 /* Remove the !uptodate folios we added */
3145 if (index > start) {
3146 shmem_undo_range(inode,
3147 (loff_t)start << PAGE_SHIFT,
3148 ((loff_t)index << PAGE_SHIFT) - 1, true);
3154 * Here is a more important optimization than it appears:
3155 * a second SGP_FALLOC on the same large folio will clear it,
3156 * making it uptodate and un-undoable if we fail later.
3158 index = folio_next_index(folio);
3159 /* Beware 32-bit wraparound */
3164 * Inform shmem_writepage() how far we have reached.
3165 * No need for lock or barrier: we have the page lock.
3167 if (!folio_test_uptodate(folio))
3168 shmem_falloc.nr_falloced += index - shmem_falloc.next;
3169 shmem_falloc.next = index;
3172 * If !uptodate, leave it that way so that freeable folios
3173 * can be recognized if we need to rollback on error later.
3174 * But mark it dirty so that memory pressure will swap rather
3175 * than free the folios we are allocating (and SGP_CACHE folios
3176 * might still be clean: we now need to mark those dirty too).
3178 folio_mark_dirty(folio);
3179 folio_unlock(folio);
3184 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
3185 i_size_write(inode, offset + len);
3187 spin_lock(&inode->i_lock);
3188 inode->i_private = NULL;
3189 spin_unlock(&inode->i_lock);
3192 file_modified(file);
3193 inode_unlock(inode);
3197 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
3199 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
3201 buf->f_type = TMPFS_MAGIC;
3202 buf->f_bsize = PAGE_SIZE;
3203 buf->f_namelen = NAME_MAX;
3204 if (sbinfo->max_blocks) {
3205 buf->f_blocks = sbinfo->max_blocks;
3207 buf->f_bfree = sbinfo->max_blocks -
3208 percpu_counter_sum(&sbinfo->used_blocks);
3210 if (sbinfo->max_inodes) {
3211 buf->f_files = sbinfo->max_inodes;
3212 buf->f_ffree = sbinfo->free_ispace / BOGO_INODE_SIZE;
3214 /* else leave those fields 0 like simple_statfs */
3216 buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
3222 * File creation. Allocate an inode, and we're done..
3225 shmem_mknod(struct mnt_idmap *idmap, struct inode *dir,
3226 struct dentry *dentry, umode_t mode, dev_t dev)
3228 struct inode *inode;
3231 inode = shmem_get_inode(idmap, dir->i_sb, dir, mode, dev, VM_NORESERVE);
3233 return PTR_ERR(inode);
3235 error = simple_acl_create(dir, inode);
3238 error = security_inode_init_security(inode, dir,
3240 shmem_initxattrs, NULL);
3241 if (error && error != -EOPNOTSUPP)
3244 error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3248 dir->i_size += BOGO_DIRENT_SIZE;
3249 dir->i_mtime = inode_set_ctime_current(dir);
3250 inode_inc_iversion(dir);
3251 d_instantiate(dentry, inode);
3252 dget(dentry); /* Extra count - pin the dentry in core */
3261 shmem_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
3262 struct file *file, umode_t mode)
3264 struct inode *inode;
3267 inode = shmem_get_inode(idmap, dir->i_sb, dir, mode, 0, VM_NORESERVE);
3269 if (IS_ERR(inode)) {
3270 error = PTR_ERR(inode);
3274 error = security_inode_init_security(inode, dir,
3276 shmem_initxattrs, NULL);
3277 if (error && error != -EOPNOTSUPP)
3279 error = simple_acl_create(dir, inode);
3282 d_tmpfile(file, inode);
3285 return finish_open_simple(file, error);
3291 static int shmem_mkdir(struct mnt_idmap *idmap, struct inode *dir,
3292 struct dentry *dentry, umode_t mode)
3296 error = shmem_mknod(idmap, dir, dentry, mode | S_IFDIR, 0);
3303 static int shmem_create(struct mnt_idmap *idmap, struct inode *dir,
3304 struct dentry *dentry, umode_t mode, bool excl)
3306 return shmem_mknod(idmap, dir, dentry, mode | S_IFREG, 0);
3312 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
3314 struct inode *inode = d_inode(old_dentry);
3318 * No ordinary (disk based) filesystem counts links as inodes;
3319 * but each new link needs a new dentry, pinning lowmem, and
3320 * tmpfs dentries cannot be pruned until they are unlinked.
3321 * But if an O_TMPFILE file is linked into the tmpfs, the
3322 * first link must skip that, to get the accounting right.
3324 if (inode->i_nlink) {
3325 ret = shmem_reserve_inode(inode->i_sb, NULL);
3330 ret = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3333 shmem_free_inode(inode->i_sb, 0);
3337 dir->i_size += BOGO_DIRENT_SIZE;
3338 dir->i_mtime = inode_set_ctime_to_ts(dir,
3339 inode_set_ctime_current(inode));
3340 inode_inc_iversion(dir);
3342 ihold(inode); /* New dentry reference */
3343 dget(dentry); /* Extra pinning count for the created dentry */
3344 d_instantiate(dentry, inode);
3349 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3351 struct inode *inode = d_inode(dentry);
3353 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3354 shmem_free_inode(inode->i_sb, 0);
3356 simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
3358 dir->i_size -= BOGO_DIRENT_SIZE;
3359 dir->i_mtime = inode_set_ctime_to_ts(dir,
3360 inode_set_ctime_current(inode));
3361 inode_inc_iversion(dir);
3363 dput(dentry); /* Undo the count from "create" - this does all the work */
3367 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3369 if (!simple_empty(dentry))
3372 drop_nlink(d_inode(dentry));
3374 return shmem_unlink(dir, dentry);
3377 static int shmem_whiteout(struct mnt_idmap *idmap,
3378 struct inode *old_dir, struct dentry *old_dentry)
3380 struct dentry *whiteout;
3383 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3387 error = shmem_mknod(idmap, old_dir, whiteout,
3388 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3394 * Cheat and hash the whiteout while the old dentry is still in
3395 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3397 * d_lookup() will consistently find one of them at this point,
3398 * not sure which one, but that isn't even important.
3405 * The VFS layer already does all the dentry stuff for rename,
3406 * we just have to decrement the usage count for the target if
3407 * it exists so that the VFS layer correctly free's it when it
3410 static int shmem_rename2(struct mnt_idmap *idmap,
3411 struct inode *old_dir, struct dentry *old_dentry,
3412 struct inode *new_dir, struct dentry *new_dentry,
3415 struct inode *inode = d_inode(old_dentry);
3416 int they_are_dirs = S_ISDIR(inode->i_mode);
3419 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3422 if (flags & RENAME_EXCHANGE)
3423 return simple_offset_rename_exchange(old_dir, old_dentry,
3424 new_dir, new_dentry);
3426 if (!simple_empty(new_dentry))
3429 if (flags & RENAME_WHITEOUT) {
3430 error = shmem_whiteout(idmap, old_dir, old_dentry);
3435 simple_offset_remove(shmem_get_offset_ctx(old_dir), old_dentry);
3436 error = simple_offset_add(shmem_get_offset_ctx(new_dir), old_dentry);
3440 if (d_really_is_positive(new_dentry)) {
3441 (void) shmem_unlink(new_dir, new_dentry);
3442 if (they_are_dirs) {
3443 drop_nlink(d_inode(new_dentry));
3444 drop_nlink(old_dir);
3446 } else if (they_are_dirs) {
3447 drop_nlink(old_dir);
3451 old_dir->i_size -= BOGO_DIRENT_SIZE;
3452 new_dir->i_size += BOGO_DIRENT_SIZE;
3453 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
3454 inode_inc_iversion(old_dir);
3455 inode_inc_iversion(new_dir);
3459 static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
3460 struct dentry *dentry, const char *symname)
3464 struct inode *inode;
3465 struct folio *folio;
3467 len = strlen(symname) + 1;
3468 if (len > PAGE_SIZE)
3469 return -ENAMETOOLONG;
3471 inode = shmem_get_inode(idmap, dir->i_sb, dir, S_IFLNK | 0777, 0,
3475 return PTR_ERR(inode);
3477 error = security_inode_init_security(inode, dir, &dentry->d_name,
3478 shmem_initxattrs, NULL);
3479 if (error && error != -EOPNOTSUPP)
3482 error = simple_offset_add(shmem_get_offset_ctx(dir), dentry);
3486 inode->i_size = len-1;
3487 if (len <= SHORT_SYMLINK_LEN) {
3488 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3489 if (!inode->i_link) {
3491 goto out_remove_offset;
3493 inode->i_op = &shmem_short_symlink_operations;
3495 inode_nohighmem(inode);
3496 error = shmem_get_folio(inode, 0, &folio, SGP_WRITE);
3498 goto out_remove_offset;
3499 inode->i_mapping->a_ops = &shmem_aops;
3500 inode->i_op = &shmem_symlink_inode_operations;
3501 memcpy(folio_address(folio), symname, len);
3502 folio_mark_uptodate(folio);
3503 folio_mark_dirty(folio);
3504 folio_unlock(folio);
3507 dir->i_size += BOGO_DIRENT_SIZE;
3508 dir->i_mtime = inode_set_ctime_current(dir);
3509 inode_inc_iversion(dir);
3510 d_instantiate(dentry, inode);
3515 simple_offset_remove(shmem_get_offset_ctx(dir), dentry);
3521 static void shmem_put_link(void *arg)
3523 folio_mark_accessed(arg);
3527 static const char *shmem_get_link(struct dentry *dentry,
3528 struct inode *inode,
3529 struct delayed_call *done)
3531 struct folio *folio = NULL;
3535 folio = filemap_get_folio(inode->i_mapping, 0);
3537 return ERR_PTR(-ECHILD);
3538 if (PageHWPoison(folio_page(folio, 0)) ||
3539 !folio_test_uptodate(folio)) {
3541 return ERR_PTR(-ECHILD);
3544 error = shmem_get_folio(inode, 0, &folio, SGP_READ);
3546 return ERR_PTR(error);
3548 return ERR_PTR(-ECHILD);
3549 if (PageHWPoison(folio_page(folio, 0))) {
3550 folio_unlock(folio);
3552 return ERR_PTR(-ECHILD);
3554 folio_unlock(folio);
3556 set_delayed_call(done, shmem_put_link, folio);
3557 return folio_address(folio);
3560 #ifdef CONFIG_TMPFS_XATTR
3562 static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
3564 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3566 fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
3571 static int shmem_fileattr_set(struct mnt_idmap *idmap,
3572 struct dentry *dentry, struct fileattr *fa)
3574 struct inode *inode = d_inode(dentry);
3575 struct shmem_inode_info *info = SHMEM_I(inode);
3577 if (fileattr_has_fsx(fa))
3579 if (fa->flags & ~SHMEM_FL_USER_MODIFIABLE)
3582 info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
3583 (fa->flags & SHMEM_FL_USER_MODIFIABLE);
3585 shmem_set_inode_flags(inode, info->fsflags);
3586 inode_set_ctime_current(inode);
3587 inode_inc_iversion(inode);
3592 * Superblocks without xattr inode operations may get some security.* xattr
3593 * support from the LSM "for free". As soon as we have any other xattrs
3594 * like ACLs, we also need to implement the security.* handlers at
3595 * filesystem level, though.
3599 * Callback for security_inode_init_security() for acquiring xattrs.
3601 static int shmem_initxattrs(struct inode *inode,
3602 const struct xattr *xattr_array,
3605 struct shmem_inode_info *info = SHMEM_I(inode);
3606 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3607 const struct xattr *xattr;
3608 struct simple_xattr *new_xattr;
3612 if (sbinfo->max_inodes) {
3613 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3614 ispace += simple_xattr_space(xattr->name,
3615 xattr->value_len + XATTR_SECURITY_PREFIX_LEN);
3618 raw_spin_lock(&sbinfo->stat_lock);
3619 if (sbinfo->free_ispace < ispace)
3622 sbinfo->free_ispace -= ispace;
3623 raw_spin_unlock(&sbinfo->stat_lock);
3629 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3630 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3634 len = strlen(xattr->name) + 1;
3635 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3636 GFP_KERNEL_ACCOUNT);
3637 if (!new_xattr->name) {
3642 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3643 XATTR_SECURITY_PREFIX_LEN);
3644 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3647 simple_xattr_add(&info->xattrs, new_xattr);
3650 if (xattr->name != NULL) {
3652 raw_spin_lock(&sbinfo->stat_lock);
3653 sbinfo->free_ispace += ispace;
3654 raw_spin_unlock(&sbinfo->stat_lock);
3656 simple_xattrs_free(&info->xattrs, NULL);
3663 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3664 struct dentry *unused, struct inode *inode,
3665 const char *name, void *buffer, size_t size)
3667 struct shmem_inode_info *info = SHMEM_I(inode);
3669 name = xattr_full_name(handler, name);
3670 return simple_xattr_get(&info->xattrs, name, buffer, size);
3673 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3674 struct mnt_idmap *idmap,
3675 struct dentry *unused, struct inode *inode,
3676 const char *name, const void *value,
3677 size_t size, int flags)
3679 struct shmem_inode_info *info = SHMEM_I(inode);
3680 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3681 struct simple_xattr *old_xattr;
3684 name = xattr_full_name(handler, name);
3685 if (value && sbinfo->max_inodes) {
3686 ispace = simple_xattr_space(name, size);
3687 raw_spin_lock(&sbinfo->stat_lock);
3688 if (sbinfo->free_ispace < ispace)
3691 sbinfo->free_ispace -= ispace;
3692 raw_spin_unlock(&sbinfo->stat_lock);
3697 old_xattr = simple_xattr_set(&info->xattrs, name, value, size, flags);
3698 if (!IS_ERR(old_xattr)) {
3700 if (old_xattr && sbinfo->max_inodes)
3701 ispace = simple_xattr_space(old_xattr->name,
3703 simple_xattr_free(old_xattr);
3705 inode_set_ctime_current(inode);
3706 inode_inc_iversion(inode);
3709 raw_spin_lock(&sbinfo->stat_lock);
3710 sbinfo->free_ispace += ispace;
3711 raw_spin_unlock(&sbinfo->stat_lock);
3713 return PTR_ERR(old_xattr);
3716 static const struct xattr_handler shmem_security_xattr_handler = {
3717 .prefix = XATTR_SECURITY_PREFIX,
3718 .get = shmem_xattr_handler_get,
3719 .set = shmem_xattr_handler_set,
3722 static const struct xattr_handler shmem_trusted_xattr_handler = {
3723 .prefix = XATTR_TRUSTED_PREFIX,
3724 .get = shmem_xattr_handler_get,
3725 .set = shmem_xattr_handler_set,
3728 static const struct xattr_handler shmem_user_xattr_handler = {
3729 .prefix = XATTR_USER_PREFIX,
3730 .get = shmem_xattr_handler_get,
3731 .set = shmem_xattr_handler_set,
3734 static const struct xattr_handler *shmem_xattr_handlers[] = {
3735 &shmem_security_xattr_handler,
3736 &shmem_trusted_xattr_handler,
3737 &shmem_user_xattr_handler,
3741 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3743 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3744 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3746 #endif /* CONFIG_TMPFS_XATTR */
3748 static const struct inode_operations shmem_short_symlink_operations = {
3749 .getattr = shmem_getattr,
3750 .setattr = shmem_setattr,
3751 .get_link = simple_get_link,
3752 #ifdef CONFIG_TMPFS_XATTR
3753 .listxattr = shmem_listxattr,
3757 static const struct inode_operations shmem_symlink_inode_operations = {
3758 .getattr = shmem_getattr,
3759 .setattr = shmem_setattr,
3760 .get_link = shmem_get_link,
3761 #ifdef CONFIG_TMPFS_XATTR
3762 .listxattr = shmem_listxattr,
3766 static struct dentry *shmem_get_parent(struct dentry *child)
3768 return ERR_PTR(-ESTALE);
3771 static int shmem_match(struct inode *ino, void *vfh)
3775 inum = (inum << 32) | fh[1];
3776 return ino->i_ino == inum && fh[0] == ino->i_generation;
3779 /* Find any alias of inode, but prefer a hashed alias */
3780 static struct dentry *shmem_find_alias(struct inode *inode)
3782 struct dentry *alias = d_find_alias(inode);
3784 return alias ?: d_find_any_alias(inode);
3788 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3789 struct fid *fid, int fh_len, int fh_type)
3791 struct inode *inode;
3792 struct dentry *dentry = NULL;
3799 inum = (inum << 32) | fid->raw[1];
3801 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3802 shmem_match, fid->raw);
3804 dentry = shmem_find_alias(inode);
3811 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3812 struct inode *parent)
3816 return FILEID_INVALID;
3819 if (inode_unhashed(inode)) {
3820 /* Unfortunately insert_inode_hash is not idempotent,
3821 * so as we hash inodes here rather than at creation
3822 * time, we need a lock to ensure we only try
3825 static DEFINE_SPINLOCK(lock);
3827 if (inode_unhashed(inode))
3828 __insert_inode_hash(inode,
3829 inode->i_ino + inode->i_generation);
3833 fh[0] = inode->i_generation;
3834 fh[1] = inode->i_ino;
3835 fh[2] = ((__u64)inode->i_ino) >> 32;
3841 static const struct export_operations shmem_export_ops = {
3842 .get_parent = shmem_get_parent,
3843 .encode_fh = shmem_encode_fh,
3844 .fh_to_dentry = shmem_fh_to_dentry,
3862 Opt_usrquota_block_hardlimit,
3863 Opt_usrquota_inode_hardlimit,
3864 Opt_grpquota_block_hardlimit,
3865 Opt_grpquota_inode_hardlimit,
3868 static const struct constant_table shmem_param_enums_huge[] = {
3869 {"never", SHMEM_HUGE_NEVER },
3870 {"always", SHMEM_HUGE_ALWAYS },
3871 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3872 {"advise", SHMEM_HUGE_ADVISE },
3876 const struct fs_parameter_spec shmem_fs_parameters[] = {
3877 fsparam_u32 ("gid", Opt_gid),
3878 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3879 fsparam_u32oct("mode", Opt_mode),
3880 fsparam_string("mpol", Opt_mpol),
3881 fsparam_string("nr_blocks", Opt_nr_blocks),
3882 fsparam_string("nr_inodes", Opt_nr_inodes),
3883 fsparam_string("size", Opt_size),
3884 fsparam_u32 ("uid", Opt_uid),
3885 fsparam_flag ("inode32", Opt_inode32),
3886 fsparam_flag ("inode64", Opt_inode64),
3887 fsparam_flag ("noswap", Opt_noswap),
3888 #ifdef CONFIG_TMPFS_QUOTA
3889 fsparam_flag ("quota", Opt_quota),
3890 fsparam_flag ("usrquota", Opt_usrquota),
3891 fsparam_flag ("grpquota", Opt_grpquota),
3892 fsparam_string("usrquota_block_hardlimit", Opt_usrquota_block_hardlimit),
3893 fsparam_string("usrquota_inode_hardlimit", Opt_usrquota_inode_hardlimit),
3894 fsparam_string("grpquota_block_hardlimit", Opt_grpquota_block_hardlimit),
3895 fsparam_string("grpquota_inode_hardlimit", Opt_grpquota_inode_hardlimit),
3900 static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3902 struct shmem_options *ctx = fc->fs_private;
3903 struct fs_parse_result result;
3904 unsigned long long size;
3910 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3916 size = memparse(param->string, &rest);
3918 size <<= PAGE_SHIFT;
3919 size *= totalram_pages();
3925 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3926 ctx->seen |= SHMEM_SEEN_BLOCKS;
3929 ctx->blocks = memparse(param->string, &rest);
3930 if (*rest || ctx->blocks > LONG_MAX)
3932 ctx->seen |= SHMEM_SEEN_BLOCKS;
3935 ctx->inodes = memparse(param->string, &rest);
3936 if (*rest || ctx->inodes > ULONG_MAX / BOGO_INODE_SIZE)
3938 ctx->seen |= SHMEM_SEEN_INODES;
3941 ctx->mode = result.uint_32 & 07777;
3944 kuid = make_kuid(current_user_ns(), result.uint_32);
3945 if (!uid_valid(kuid))
3949 * The requested uid must be representable in the
3950 * filesystem's idmapping.
3952 if (!kuid_has_mapping(fc->user_ns, kuid))
3958 kgid = make_kgid(current_user_ns(), result.uint_32);
3959 if (!gid_valid(kgid))
3963 * The requested gid must be representable in the
3964 * filesystem's idmapping.
3966 if (!kgid_has_mapping(fc->user_ns, kgid))
3972 ctx->huge = result.uint_32;
3973 if (ctx->huge != SHMEM_HUGE_NEVER &&
3974 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
3975 has_transparent_hugepage()))
3976 goto unsupported_parameter;
3977 ctx->seen |= SHMEM_SEEN_HUGE;
3980 if (IS_ENABLED(CONFIG_NUMA)) {
3981 mpol_put(ctx->mpol);
3983 if (mpol_parse_str(param->string, &ctx->mpol))
3987 goto unsupported_parameter;
3989 ctx->full_inums = false;
3990 ctx->seen |= SHMEM_SEEN_INUMS;
3993 if (sizeof(ino_t) < 8) {
3995 "Cannot use inode64 with <64bit inums in kernel\n");
3997 ctx->full_inums = true;
3998 ctx->seen |= SHMEM_SEEN_INUMS;
4001 if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN)) {
4003 "Turning off swap in unprivileged tmpfs mounts unsupported");
4006 ctx->seen |= SHMEM_SEEN_NOSWAP;
4009 if (fc->user_ns != &init_user_ns)
4010 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4011 ctx->seen |= SHMEM_SEEN_QUOTA;
4012 ctx->quota_types |= (QTYPE_MASK_USR | QTYPE_MASK_GRP);
4015 if (fc->user_ns != &init_user_ns)
4016 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4017 ctx->seen |= SHMEM_SEEN_QUOTA;
4018 ctx->quota_types |= QTYPE_MASK_USR;
4021 if (fc->user_ns != &init_user_ns)
4022 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4023 ctx->seen |= SHMEM_SEEN_QUOTA;
4024 ctx->quota_types |= QTYPE_MASK_GRP;
4026 case Opt_usrquota_block_hardlimit:
4027 size = memparse(param->string, &rest);
4030 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4032 "User quota block hardlimit too large.");
4033 ctx->qlimits.usrquota_bhardlimit = size;
4035 case Opt_grpquota_block_hardlimit:
4036 size = memparse(param->string, &rest);
4039 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4041 "Group quota block hardlimit too large.");
4042 ctx->qlimits.grpquota_bhardlimit = size;
4044 case Opt_usrquota_inode_hardlimit:
4045 size = memparse(param->string, &rest);
4048 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4050 "User quota inode hardlimit too large.");
4051 ctx->qlimits.usrquota_ihardlimit = size;
4053 case Opt_grpquota_inode_hardlimit:
4054 size = memparse(param->string, &rest);
4057 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4059 "Group quota inode hardlimit too large.");
4060 ctx->qlimits.grpquota_ihardlimit = size;
4065 unsupported_parameter:
4066 return invalfc(fc, "Unsupported parameter '%s'", param->key);
4068 return invalfc(fc, "Bad value for '%s'", param->key);
4071 static int shmem_parse_options(struct fs_context *fc, void *data)
4073 char *options = data;
4076 int err = security_sb_eat_lsm_opts(options, &fc->security);
4081 while (options != NULL) {
4082 char *this_char = options;
4085 * NUL-terminate this option: unfortunately,
4086 * mount options form a comma-separated list,
4087 * but mpol's nodelist may also contain commas.
4089 options = strchr(options, ',');
4090 if (options == NULL)
4093 if (!isdigit(*options)) {
4099 char *value = strchr(this_char, '=');
4105 len = strlen(value);
4107 err = vfs_parse_fs_string(fc, this_char, value, len);
4116 * Reconfigure a shmem filesystem.
4118 static int shmem_reconfigure(struct fs_context *fc)
4120 struct shmem_options *ctx = fc->fs_private;
4121 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
4122 unsigned long used_isp;
4123 struct mempolicy *mpol = NULL;
4126 raw_spin_lock(&sbinfo->stat_lock);
4127 used_isp = sbinfo->max_inodes * BOGO_INODE_SIZE - sbinfo->free_ispace;
4129 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
4130 if (!sbinfo->max_blocks) {
4131 err = "Cannot retroactively limit size";
4134 if (percpu_counter_compare(&sbinfo->used_blocks,
4136 err = "Too small a size for current use";
4140 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
4141 if (!sbinfo->max_inodes) {
4142 err = "Cannot retroactively limit inodes";
4145 if (ctx->inodes * BOGO_INODE_SIZE < used_isp) {
4146 err = "Too few inodes for current use";
4151 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
4152 sbinfo->next_ino > UINT_MAX) {
4153 err = "Current inum too high to switch to 32-bit inums";
4156 if ((ctx->seen & SHMEM_SEEN_NOSWAP) && ctx->noswap && !sbinfo->noswap) {
4157 err = "Cannot disable swap on remount";
4160 if (!(ctx->seen & SHMEM_SEEN_NOSWAP) && !ctx->noswap && sbinfo->noswap) {
4161 err = "Cannot enable swap on remount if it was disabled on first mount";
4165 if (ctx->seen & SHMEM_SEEN_QUOTA &&
4166 !sb_any_quota_loaded(fc->root->d_sb)) {
4167 err = "Cannot enable quota on remount";
4171 #ifdef CONFIG_TMPFS_QUOTA
4172 #define CHANGED_LIMIT(name) \
4173 (ctx->qlimits.name## hardlimit && \
4174 (ctx->qlimits.name## hardlimit != sbinfo->qlimits.name## hardlimit))
4176 if (CHANGED_LIMIT(usrquota_b) || CHANGED_LIMIT(usrquota_i) ||
4177 CHANGED_LIMIT(grpquota_b) || CHANGED_LIMIT(grpquota_i)) {
4178 err = "Cannot change global quota limit on remount";
4181 #endif /* CONFIG_TMPFS_QUOTA */
4183 if (ctx->seen & SHMEM_SEEN_HUGE)
4184 sbinfo->huge = ctx->huge;
4185 if (ctx->seen & SHMEM_SEEN_INUMS)
4186 sbinfo->full_inums = ctx->full_inums;
4187 if (ctx->seen & SHMEM_SEEN_BLOCKS)
4188 sbinfo->max_blocks = ctx->blocks;
4189 if (ctx->seen & SHMEM_SEEN_INODES) {
4190 sbinfo->max_inodes = ctx->inodes;
4191 sbinfo->free_ispace = ctx->inodes * BOGO_INODE_SIZE - used_isp;
4195 * Preserve previous mempolicy unless mpol remount option was specified.
4198 mpol = sbinfo->mpol;
4199 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
4204 sbinfo->noswap = true;
4206 raw_spin_unlock(&sbinfo->stat_lock);
4210 raw_spin_unlock(&sbinfo->stat_lock);
4211 return invalfc(fc, "%s", err);
4214 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
4216 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
4217 struct mempolicy *mpol;
4219 if (sbinfo->max_blocks != shmem_default_max_blocks())
4220 seq_printf(seq, ",size=%luk", K(sbinfo->max_blocks));
4221 if (sbinfo->max_inodes != shmem_default_max_inodes())
4222 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
4223 if (sbinfo->mode != (0777 | S_ISVTX))
4224 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
4225 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
4226 seq_printf(seq, ",uid=%u",
4227 from_kuid_munged(&init_user_ns, sbinfo->uid));
4228 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
4229 seq_printf(seq, ",gid=%u",
4230 from_kgid_munged(&init_user_ns, sbinfo->gid));
4233 * Showing inode{64,32} might be useful even if it's the system default,
4234 * since then people don't have to resort to checking both here and
4235 * /proc/config.gz to confirm 64-bit inums were successfully applied
4236 * (which may not even exist if IKCONFIG_PROC isn't enabled).
4238 * We hide it when inode64 isn't the default and we are using 32-bit
4239 * inodes, since that probably just means the feature isn't even under
4244 * +-----------------+-----------------+
4245 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
4246 * +------------------+-----------------+-----------------+
4247 * | full_inums=true | show | show |
4248 * | full_inums=false | show | hide |
4249 * +------------------+-----------------+-----------------+
4252 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
4253 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
4254 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4255 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
4257 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
4259 mpol = shmem_get_sbmpol(sbinfo);
4260 shmem_show_mpol(seq, mpol);
4263 seq_printf(seq, ",noswap");
4267 #endif /* CONFIG_TMPFS */
4269 static void shmem_put_super(struct super_block *sb)
4271 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
4273 #ifdef CONFIG_TMPFS_QUOTA
4274 shmem_disable_quotas(sb);
4276 free_percpu(sbinfo->ino_batch);
4277 percpu_counter_destroy(&sbinfo->used_blocks);
4278 mpol_put(sbinfo->mpol);
4280 sb->s_fs_info = NULL;
4283 static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
4285 struct shmem_options *ctx = fc->fs_private;
4286 struct inode *inode;
4287 struct shmem_sb_info *sbinfo;
4288 int error = -ENOMEM;
4290 /* Round up to L1_CACHE_BYTES to resist false sharing */
4291 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
4292 L1_CACHE_BYTES), GFP_KERNEL);
4296 sb->s_fs_info = sbinfo;
4300 * Per default we only allow half of the physical ram per
4301 * tmpfs instance, limiting inodes to one per page of lowmem;
4302 * but the internal instance is left unlimited.
4304 if (!(sb->s_flags & SB_KERNMOUNT)) {
4305 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
4306 ctx->blocks = shmem_default_max_blocks();
4307 if (!(ctx->seen & SHMEM_SEEN_INODES))
4308 ctx->inodes = shmem_default_max_inodes();
4309 if (!(ctx->seen & SHMEM_SEEN_INUMS))
4310 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
4311 sbinfo->noswap = ctx->noswap;
4313 sb->s_flags |= SB_NOUSER;
4315 sb->s_export_op = &shmem_export_ops;
4316 sb->s_flags |= SB_NOSEC | SB_I_VERSION;
4318 sb->s_flags |= SB_NOUSER;
4320 sbinfo->max_blocks = ctx->blocks;
4321 sbinfo->max_inodes = ctx->inodes;
4322 sbinfo->free_ispace = sbinfo->max_inodes * BOGO_INODE_SIZE;
4323 if (sb->s_flags & SB_KERNMOUNT) {
4324 sbinfo->ino_batch = alloc_percpu(ino_t);
4325 if (!sbinfo->ino_batch)
4328 sbinfo->uid = ctx->uid;
4329 sbinfo->gid = ctx->gid;
4330 sbinfo->full_inums = ctx->full_inums;
4331 sbinfo->mode = ctx->mode;
4332 sbinfo->huge = ctx->huge;
4333 sbinfo->mpol = ctx->mpol;
4336 raw_spin_lock_init(&sbinfo->stat_lock);
4337 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
4339 spin_lock_init(&sbinfo->shrinklist_lock);
4340 INIT_LIST_HEAD(&sbinfo->shrinklist);
4342 sb->s_maxbytes = MAX_LFS_FILESIZE;
4343 sb->s_blocksize = PAGE_SIZE;
4344 sb->s_blocksize_bits = PAGE_SHIFT;
4345 sb->s_magic = TMPFS_MAGIC;
4346 sb->s_op = &shmem_ops;
4347 sb->s_time_gran = 1;
4348 #ifdef CONFIG_TMPFS_XATTR
4349 sb->s_xattr = shmem_xattr_handlers;
4351 #ifdef CONFIG_TMPFS_POSIX_ACL
4352 sb->s_flags |= SB_POSIXACL;
4354 uuid_gen(&sb->s_uuid);
4356 #ifdef CONFIG_TMPFS_QUOTA
4357 if (ctx->seen & SHMEM_SEEN_QUOTA) {
4358 sb->dq_op = &shmem_quota_operations;
4359 sb->s_qcop = &dquot_quotactl_sysfile_ops;
4360 sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
4362 /* Copy the default limits from ctx into sbinfo */
4363 memcpy(&sbinfo->qlimits, &ctx->qlimits,
4364 sizeof(struct shmem_quota_limits));
4366 if (shmem_enable_quotas(sb, ctx->quota_types))
4369 #endif /* CONFIG_TMPFS_QUOTA */
4371 inode = shmem_get_inode(&nop_mnt_idmap, sb, NULL, S_IFDIR | sbinfo->mode, 0,
4373 if (IS_ERR(inode)) {
4374 error = PTR_ERR(inode);
4377 inode->i_uid = sbinfo->uid;
4378 inode->i_gid = sbinfo->gid;
4379 sb->s_root = d_make_root(inode);
4385 shmem_put_super(sb);
4389 static int shmem_get_tree(struct fs_context *fc)
4391 return get_tree_nodev(fc, shmem_fill_super);
4394 static void shmem_free_fc(struct fs_context *fc)
4396 struct shmem_options *ctx = fc->fs_private;
4399 mpol_put(ctx->mpol);
4404 static const struct fs_context_operations shmem_fs_context_ops = {
4405 .free = shmem_free_fc,
4406 .get_tree = shmem_get_tree,
4408 .parse_monolithic = shmem_parse_options,
4409 .parse_param = shmem_parse_one,
4410 .reconfigure = shmem_reconfigure,
4414 static struct kmem_cache *shmem_inode_cachep;
4416 static struct inode *shmem_alloc_inode(struct super_block *sb)
4418 struct shmem_inode_info *info;
4419 info = alloc_inode_sb(sb, shmem_inode_cachep, GFP_KERNEL);
4422 return &info->vfs_inode;
4425 static void shmem_free_in_core_inode(struct inode *inode)
4427 if (S_ISLNK(inode->i_mode))
4428 kfree(inode->i_link);
4429 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
4432 static void shmem_destroy_inode(struct inode *inode)
4434 if (S_ISREG(inode->i_mode))
4435 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
4436 if (S_ISDIR(inode->i_mode))
4437 simple_offset_destroy(shmem_get_offset_ctx(inode));
4440 static void shmem_init_inode(void *foo)
4442 struct shmem_inode_info *info = foo;
4443 inode_init_once(&info->vfs_inode);
4446 static void shmem_init_inodecache(void)
4448 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
4449 sizeof(struct shmem_inode_info),
4450 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
4453 static void shmem_destroy_inodecache(void)
4455 kmem_cache_destroy(shmem_inode_cachep);
4458 /* Keep the page in page cache instead of truncating it */
4459 static int shmem_error_remove_page(struct address_space *mapping,
4465 const struct address_space_operations shmem_aops = {
4466 .writepage = shmem_writepage,
4467 .dirty_folio = noop_dirty_folio,
4469 .write_begin = shmem_write_begin,
4470 .write_end = shmem_write_end,
4472 #ifdef CONFIG_MIGRATION
4473 .migrate_folio = migrate_folio,
4475 .error_remove_page = shmem_error_remove_page,
4477 EXPORT_SYMBOL(shmem_aops);
4479 static const struct file_operations shmem_file_operations = {
4481 .open = shmem_file_open,
4482 .get_unmapped_area = shmem_get_unmapped_area,
4484 .llseek = shmem_file_llseek,
4485 .read_iter = shmem_file_read_iter,
4486 .write_iter = shmem_file_write_iter,
4487 .fsync = noop_fsync,
4488 .splice_read = shmem_file_splice_read,
4489 .splice_write = iter_file_splice_write,
4490 .fallocate = shmem_fallocate,
4494 static const struct inode_operations shmem_inode_operations = {
4495 .getattr = shmem_getattr,
4496 .setattr = shmem_setattr,
4497 #ifdef CONFIG_TMPFS_XATTR
4498 .listxattr = shmem_listxattr,
4499 .set_acl = simple_set_acl,
4500 .fileattr_get = shmem_fileattr_get,
4501 .fileattr_set = shmem_fileattr_set,
4505 static const struct inode_operations shmem_dir_inode_operations = {
4507 .getattr = shmem_getattr,
4508 .create = shmem_create,
4509 .lookup = simple_lookup,
4511 .unlink = shmem_unlink,
4512 .symlink = shmem_symlink,
4513 .mkdir = shmem_mkdir,
4514 .rmdir = shmem_rmdir,
4515 .mknod = shmem_mknod,
4516 .rename = shmem_rename2,
4517 .tmpfile = shmem_tmpfile,
4518 .get_offset_ctx = shmem_get_offset_ctx,
4520 #ifdef CONFIG_TMPFS_XATTR
4521 .listxattr = shmem_listxattr,
4522 .fileattr_get = shmem_fileattr_get,
4523 .fileattr_set = shmem_fileattr_set,
4525 #ifdef CONFIG_TMPFS_POSIX_ACL
4526 .setattr = shmem_setattr,
4527 .set_acl = simple_set_acl,
4531 static const struct inode_operations shmem_special_inode_operations = {
4532 .getattr = shmem_getattr,
4533 #ifdef CONFIG_TMPFS_XATTR
4534 .listxattr = shmem_listxattr,
4536 #ifdef CONFIG_TMPFS_POSIX_ACL
4537 .setattr = shmem_setattr,
4538 .set_acl = simple_set_acl,
4542 static const struct super_operations shmem_ops = {
4543 .alloc_inode = shmem_alloc_inode,
4544 .free_inode = shmem_free_in_core_inode,
4545 .destroy_inode = shmem_destroy_inode,
4547 .statfs = shmem_statfs,
4548 .show_options = shmem_show_options,
4550 #ifdef CONFIG_TMPFS_QUOTA
4551 .get_dquots = shmem_get_dquots,
4553 .evict_inode = shmem_evict_inode,
4554 .drop_inode = generic_delete_inode,
4555 .put_super = shmem_put_super,
4556 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4557 .nr_cached_objects = shmem_unused_huge_count,
4558 .free_cached_objects = shmem_unused_huge_scan,
4562 static const struct vm_operations_struct shmem_vm_ops = {
4563 .fault = shmem_fault,
4564 .map_pages = filemap_map_pages,
4566 .set_policy = shmem_set_policy,
4567 .get_policy = shmem_get_policy,
4571 static const struct vm_operations_struct shmem_anon_vm_ops = {
4572 .fault = shmem_fault,
4573 .map_pages = filemap_map_pages,
4575 .set_policy = shmem_set_policy,
4576 .get_policy = shmem_get_policy,
4580 int shmem_init_fs_context(struct fs_context *fc)
4582 struct shmem_options *ctx;
4584 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
4588 ctx->mode = 0777 | S_ISVTX;
4589 ctx->uid = current_fsuid();
4590 ctx->gid = current_fsgid();
4592 fc->fs_private = ctx;
4593 fc->ops = &shmem_fs_context_ops;
4597 static struct file_system_type shmem_fs_type = {
4598 .owner = THIS_MODULE,
4600 .init_fs_context = shmem_init_fs_context,
4602 .parameters = shmem_fs_parameters,
4604 .kill_sb = kill_litter_super,
4606 .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP,
4608 .fs_flags = FS_USERNS_MOUNT,
4612 void __init shmem_init(void)
4616 shmem_init_inodecache();
4618 #ifdef CONFIG_TMPFS_QUOTA
4619 error = register_quota_format(&shmem_quota_format);
4621 pr_err("Could not register quota format\n");
4626 error = register_filesystem(&shmem_fs_type);
4628 pr_err("Could not register tmpfs\n");
4632 shm_mnt = kern_mount(&shmem_fs_type);
4633 if (IS_ERR(shm_mnt)) {
4634 error = PTR_ERR(shm_mnt);
4635 pr_err("Could not kern_mount tmpfs\n");
4639 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4640 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
4641 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4643 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
4648 unregister_filesystem(&shmem_fs_type);
4650 #ifdef CONFIG_TMPFS_QUOTA
4651 unregister_quota_format(&shmem_quota_format);
4654 shmem_destroy_inodecache();
4655 shm_mnt = ERR_PTR(error);
4658 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
4659 static ssize_t shmem_enabled_show(struct kobject *kobj,
4660 struct kobj_attribute *attr, char *buf)
4662 static const int values[] = {
4664 SHMEM_HUGE_WITHIN_SIZE,
4673 for (i = 0; i < ARRAY_SIZE(values); i++) {
4674 len += sysfs_emit_at(buf, len,
4675 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
4677 shmem_format_huge(values[i]));
4680 len += sysfs_emit_at(buf, len, "\n");
4685 static ssize_t shmem_enabled_store(struct kobject *kobj,
4686 struct kobj_attribute *attr, const char *buf, size_t count)
4691 if (count + 1 > sizeof(tmp))
4693 memcpy(tmp, buf, count);
4695 if (count && tmp[count - 1] == '\n')
4696 tmp[count - 1] = '\0';
4698 huge = shmem_parse_huge(tmp);
4699 if (huge == -EINVAL)
4701 if (!has_transparent_hugepage() &&
4702 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4706 if (shmem_huge > SHMEM_HUGE_DENY)
4707 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4711 struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
4712 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4714 #else /* !CONFIG_SHMEM */
4717 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4719 * This is intended for small system where the benefits of the full
4720 * shmem code (swap-backed and resource-limited) are outweighed by
4721 * their complexity. On systems without swap this code should be
4722 * effectively equivalent, but much lighter weight.
4725 static struct file_system_type shmem_fs_type = {
4727 .init_fs_context = ramfs_init_fs_context,
4728 .parameters = ramfs_fs_parameters,
4729 .kill_sb = ramfs_kill_sb,
4730 .fs_flags = FS_USERNS_MOUNT,
4733 void __init shmem_init(void)
4735 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4737 shm_mnt = kern_mount(&shmem_fs_type);
4738 BUG_ON(IS_ERR(shm_mnt));
4741 int shmem_unuse(unsigned int type)
4746 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
4751 void shmem_unlock_mapping(struct address_space *mapping)
4756 unsigned long shmem_get_unmapped_area(struct file *file,
4757 unsigned long addr, unsigned long len,
4758 unsigned long pgoff, unsigned long flags)
4760 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4764 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4766 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4768 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4770 #define shmem_vm_ops generic_file_vm_ops
4771 #define shmem_anon_vm_ops generic_file_vm_ops
4772 #define shmem_file_operations ramfs_file_operations
4773 #define shmem_acct_size(flags, size) 0
4774 #define shmem_unacct_size(flags, size) do {} while (0)
4776 static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap, struct super_block *sb, struct inode *dir,
4777 umode_t mode, dev_t dev, unsigned long flags)
4779 struct inode *inode = ramfs_get_inode(sb, dir, mode, dev);
4780 return inode ? inode : ERR_PTR(-ENOSPC);
4783 #endif /* CONFIG_SHMEM */
4787 static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4788 unsigned long flags, unsigned int i_flags)
4790 struct inode *inode;
4794 return ERR_CAST(mnt);
4796 if (size < 0 || size > MAX_LFS_FILESIZE)
4797 return ERR_PTR(-EINVAL);
4799 if (shmem_acct_size(flags, size))
4800 return ERR_PTR(-ENOMEM);
4802 if (is_idmapped_mnt(mnt))
4803 return ERR_PTR(-EINVAL);
4805 inode = shmem_get_inode(&nop_mnt_idmap, mnt->mnt_sb, NULL,
4806 S_IFREG | S_IRWXUGO, 0, flags);
4808 if (IS_ERR(inode)) {
4809 shmem_unacct_size(flags, size);
4810 return ERR_CAST(inode);
4812 inode->i_flags |= i_flags;
4813 inode->i_size = size;
4814 clear_nlink(inode); /* It is unlinked */
4815 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4817 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4818 &shmem_file_operations);
4825 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4826 * kernel internal. There will be NO LSM permission checks against the
4827 * underlying inode. So users of this interface must do LSM checks at a
4828 * higher layer. The users are the big_key and shm implementations. LSM
4829 * checks are provided at the key or shm level rather than the inode.
4830 * @name: name for dentry (to be seen in /proc/<pid>/maps
4831 * @size: size to be set for the file
4832 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4834 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4836 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4840 * shmem_file_setup - get an unlinked file living in tmpfs
4841 * @name: name for dentry (to be seen in /proc/<pid>/maps
4842 * @size: size to be set for the file
4843 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4845 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4847 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4849 EXPORT_SYMBOL_GPL(shmem_file_setup);
4852 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4853 * @mnt: the tmpfs mount where the file will be created
4854 * @name: name for dentry (to be seen in /proc/<pid>/maps
4855 * @size: size to be set for the file
4856 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4858 struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4859 loff_t size, unsigned long flags)
4861 return __shmem_file_setup(mnt, name, size, flags, 0);
4863 EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4866 * shmem_zero_setup - setup a shared anonymous mapping
4867 * @vma: the vma to be mmapped is prepared by do_mmap
4869 int shmem_zero_setup(struct vm_area_struct *vma)
4872 loff_t size = vma->vm_end - vma->vm_start;
4875 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4876 * between XFS directory reading and selinux: since this file is only
4877 * accessible to the user through its mapping, use S_PRIVATE flag to
4878 * bypass file security, in the same way as shmem_kernel_file_setup().
4880 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4882 return PTR_ERR(file);
4886 vma->vm_file = file;
4887 vma->vm_ops = &shmem_anon_vm_ops;
4893 * shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
4894 * @mapping: the folio's address_space
4895 * @index: the folio index
4896 * @gfp: the page allocator flags to use if allocating
4898 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4899 * with any new page allocations done using the specified allocation flags.
4900 * But read_cache_page_gfp() uses the ->read_folio() method: which does not
4901 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4902 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4904 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4905 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4907 struct folio *shmem_read_folio_gfp(struct address_space *mapping,
4908 pgoff_t index, gfp_t gfp)
4911 struct inode *inode = mapping->host;
4912 struct folio *folio;
4915 BUG_ON(!shmem_mapping(mapping));
4916 error = shmem_get_folio_gfp(inode, index, &folio, SGP_CACHE,
4917 gfp, NULL, NULL, NULL);
4919 return ERR_PTR(error);
4921 folio_unlock(folio);
4925 * The tiny !SHMEM case uses ramfs without swap
4927 return mapping_read_folio_gfp(mapping, index, gfp);
4930 EXPORT_SYMBOL_GPL(shmem_read_folio_gfp);
4932 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4933 pgoff_t index, gfp_t gfp)
4935 struct folio *folio = shmem_read_folio_gfp(mapping, index, gfp);
4939 return &folio->page;
4941 page = folio_file_page(folio, index);
4942 if (PageHWPoison(page)) {
4944 return ERR_PTR(-EIO);
4949 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);