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/swap.h>
37 #include <linux/uio.h>
38 #include <linux/hugetlb.h>
39 #include <linux/fs_parser.h>
40 #include <linux/swapfile.h>
43 static struct vfsmount *shm_mnt;
47 * This virtual memory filesystem is heavily based on the ramfs. It
48 * extends ramfs by the ability to use swap and honor resource limits
49 * which makes it a completely usable filesystem.
52 #include <linux/xattr.h>
53 #include <linux/exportfs.h>
54 #include <linux/posix_acl.h>
55 #include <linux/posix_acl_xattr.h>
56 #include <linux/mman.h>
57 #include <linux/string.h>
58 #include <linux/slab.h>
59 #include <linux/backing-dev.h>
60 #include <linux/shmem_fs.h>
61 #include <linux/writeback.h>
62 #include <linux/pagevec.h>
63 #include <linux/percpu_counter.h>
64 #include <linux/falloc.h>
65 #include <linux/splice.h>
66 #include <linux/security.h>
67 #include <linux/swapops.h>
68 #include <linux/mempolicy.h>
69 #include <linux/namei.h>
70 #include <linux/ctype.h>
71 #include <linux/migrate.h>
72 #include <linux/highmem.h>
73 #include <linux/seq_file.h>
74 #include <linux/magic.h>
75 #include <linux/syscalls.h>
76 #include <linux/fcntl.h>
77 #include <uapi/linux/memfd.h>
78 #include <linux/userfaultfd_k.h>
79 #include <linux/rmap.h>
80 #include <linux/uuid.h>
82 #include <linux/uaccess.h>
86 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
87 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
89 /* Pretend that each entry is of this size in directory's i_size */
90 #define BOGO_DIRENT_SIZE 20
92 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
93 #define SHORT_SYMLINK_LEN 128
96 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
97 * inode->i_private (with i_rwsem making sure that it has only one user at
98 * a time): we would prefer not to enlarge the shmem inode just for that.
100 struct shmem_falloc {
101 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
102 pgoff_t start; /* start of range currently being fallocated */
103 pgoff_t next; /* the next page offset to be fallocated */
104 pgoff_t nr_falloced; /* how many new pages have been fallocated */
105 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
108 struct shmem_options {
109 unsigned long long blocks;
110 unsigned long long inodes;
111 struct mempolicy *mpol;
118 #define SHMEM_SEEN_BLOCKS 1
119 #define SHMEM_SEEN_INODES 2
120 #define SHMEM_SEEN_HUGE 4
121 #define SHMEM_SEEN_INUMS 8
125 static unsigned long shmem_default_max_blocks(void)
127 return totalram_pages() / 2;
130 static unsigned long shmem_default_max_inodes(void)
132 unsigned long nr_pages = totalram_pages();
134 return min(nr_pages - totalhigh_pages(), nr_pages / 2);
138 static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
139 struct folio **foliop, enum sgp_type sgp,
140 gfp_t gfp, struct vm_area_struct *vma,
141 vm_fault_t *fault_type);
142 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
143 struct page **pagep, enum sgp_type sgp,
144 gfp_t gfp, struct vm_area_struct *vma,
145 struct vm_fault *vmf, vm_fault_t *fault_type);
147 int shmem_getpage(struct inode *inode, pgoff_t index,
148 struct page **pagep, enum sgp_type sgp)
150 return shmem_getpage_gfp(inode, index, pagep, sgp,
151 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
154 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
156 return sb->s_fs_info;
160 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
161 * for shared memory and for shared anonymous (/dev/zero) mappings
162 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
163 * consistent with the pre-accounting of private mappings ...
165 static inline int shmem_acct_size(unsigned long flags, loff_t size)
167 return (flags & VM_NORESERVE) ?
168 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
171 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
173 if (!(flags & VM_NORESERVE))
174 vm_unacct_memory(VM_ACCT(size));
177 static inline int shmem_reacct_size(unsigned long flags,
178 loff_t oldsize, loff_t newsize)
180 if (!(flags & VM_NORESERVE)) {
181 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
182 return security_vm_enough_memory_mm(current->mm,
183 VM_ACCT(newsize) - VM_ACCT(oldsize));
184 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
185 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
191 * ... whereas tmpfs objects are accounted incrementally as
192 * pages are allocated, in order to allow large sparse files.
193 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
194 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
196 static inline int shmem_acct_block(unsigned long flags, long pages)
198 if (!(flags & VM_NORESERVE))
201 return security_vm_enough_memory_mm(current->mm,
202 pages * VM_ACCT(PAGE_SIZE));
205 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
207 if (flags & VM_NORESERVE)
208 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
211 static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
213 struct shmem_inode_info *info = SHMEM_I(inode);
214 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
216 if (shmem_acct_block(info->flags, pages))
219 if (sbinfo->max_blocks) {
220 if (percpu_counter_compare(&sbinfo->used_blocks,
221 sbinfo->max_blocks - pages) > 0)
223 percpu_counter_add(&sbinfo->used_blocks, pages);
229 shmem_unacct_blocks(info->flags, pages);
233 static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
235 struct shmem_inode_info *info = SHMEM_I(inode);
236 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
238 if (sbinfo->max_blocks)
239 percpu_counter_sub(&sbinfo->used_blocks, pages);
240 shmem_unacct_blocks(info->flags, pages);
243 static const struct super_operations shmem_ops;
244 const struct address_space_operations shmem_aops;
245 static const struct file_operations shmem_file_operations;
246 static const struct inode_operations shmem_inode_operations;
247 static const struct inode_operations shmem_dir_inode_operations;
248 static const struct inode_operations shmem_special_inode_operations;
249 static const struct vm_operations_struct shmem_vm_ops;
250 static struct file_system_type shmem_fs_type;
252 bool vma_is_shmem(struct vm_area_struct *vma)
254 return vma->vm_ops == &shmem_vm_ops;
257 static LIST_HEAD(shmem_swaplist);
258 static DEFINE_MUTEX(shmem_swaplist_mutex);
261 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
262 * produces a novel ino for the newly allocated inode.
264 * It may also be called when making a hard link to permit the space needed by
265 * each dentry. However, in that case, no new inode number is needed since that
266 * internally draws from another pool of inode numbers (currently global
267 * get_next_ino()). This case is indicated by passing NULL as inop.
269 #define SHMEM_INO_BATCH 1024
270 static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
272 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
275 if (!(sb->s_flags & SB_KERNMOUNT)) {
276 raw_spin_lock(&sbinfo->stat_lock);
277 if (sbinfo->max_inodes) {
278 if (!sbinfo->free_inodes) {
279 raw_spin_unlock(&sbinfo->stat_lock);
282 sbinfo->free_inodes--;
285 ino = sbinfo->next_ino++;
286 if (unlikely(is_zero_ino(ino)))
287 ino = sbinfo->next_ino++;
288 if (unlikely(!sbinfo->full_inums &&
291 * Emulate get_next_ino uint wraparound for
294 if (IS_ENABLED(CONFIG_64BIT))
295 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
296 __func__, MINOR(sb->s_dev));
297 sbinfo->next_ino = 1;
298 ino = sbinfo->next_ino++;
302 raw_spin_unlock(&sbinfo->stat_lock);
305 * __shmem_file_setup, one of our callers, is lock-free: it
306 * doesn't hold stat_lock in shmem_reserve_inode since
307 * max_inodes is always 0, and is called from potentially
308 * unknown contexts. As such, use a per-cpu batched allocator
309 * which doesn't require the per-sb stat_lock unless we are at
310 * the batch boundary.
312 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
313 * shmem mounts are not exposed to userspace, so we don't need
314 * to worry about things like glibc compatibility.
318 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
320 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
321 raw_spin_lock(&sbinfo->stat_lock);
322 ino = sbinfo->next_ino;
323 sbinfo->next_ino += SHMEM_INO_BATCH;
324 raw_spin_unlock(&sbinfo->stat_lock);
325 if (unlikely(is_zero_ino(ino)))
336 static void shmem_free_inode(struct super_block *sb)
338 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
339 if (sbinfo->max_inodes) {
340 raw_spin_lock(&sbinfo->stat_lock);
341 sbinfo->free_inodes++;
342 raw_spin_unlock(&sbinfo->stat_lock);
347 * shmem_recalc_inode - recalculate the block usage of an inode
348 * @inode: inode to recalc
350 * We have to calculate the free blocks since the mm can drop
351 * undirtied hole pages behind our back.
353 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
354 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
356 * It has to be called with the spinlock held.
358 static void shmem_recalc_inode(struct inode *inode)
360 struct shmem_inode_info *info = SHMEM_I(inode);
363 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
365 info->alloced -= freed;
366 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
367 shmem_inode_unacct_blocks(inode, freed);
371 bool shmem_charge(struct inode *inode, long pages)
373 struct shmem_inode_info *info = SHMEM_I(inode);
376 if (!shmem_inode_acct_block(inode, pages))
379 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
380 inode->i_mapping->nrpages += pages;
382 spin_lock_irqsave(&info->lock, flags);
383 info->alloced += pages;
384 inode->i_blocks += pages * BLOCKS_PER_PAGE;
385 shmem_recalc_inode(inode);
386 spin_unlock_irqrestore(&info->lock, flags);
391 void shmem_uncharge(struct inode *inode, long pages)
393 struct shmem_inode_info *info = SHMEM_I(inode);
396 /* nrpages adjustment done by __filemap_remove_folio() or caller */
398 spin_lock_irqsave(&info->lock, flags);
399 info->alloced -= pages;
400 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
401 shmem_recalc_inode(inode);
402 spin_unlock_irqrestore(&info->lock, flags);
404 shmem_inode_unacct_blocks(inode, pages);
408 * Replace item expected in xarray by a new item, while holding xa_lock.
410 static int shmem_replace_entry(struct address_space *mapping,
411 pgoff_t index, void *expected, void *replacement)
413 XA_STATE(xas, &mapping->i_pages, index);
416 VM_BUG_ON(!expected);
417 VM_BUG_ON(!replacement);
418 item = xas_load(&xas);
419 if (item != expected)
421 xas_store(&xas, replacement);
426 * Sometimes, before we decide whether to proceed or to fail, we must check
427 * that an entry was not already brought back from swap by a racing thread.
429 * Checking page is not enough: by the time a SwapCache page is locked, it
430 * might be reused, and again be SwapCache, using the same swap as before.
432 static bool shmem_confirm_swap(struct address_space *mapping,
433 pgoff_t index, swp_entry_t swap)
435 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
439 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
442 * disables huge pages for the mount;
444 * enables huge pages for the mount;
445 * SHMEM_HUGE_WITHIN_SIZE:
446 * only allocate huge pages if the page will be fully within i_size,
447 * also respect fadvise()/madvise() hints;
449 * only allocate huge pages if requested with fadvise()/madvise();
452 #define SHMEM_HUGE_NEVER 0
453 #define SHMEM_HUGE_ALWAYS 1
454 #define SHMEM_HUGE_WITHIN_SIZE 2
455 #define SHMEM_HUGE_ADVISE 3
459 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
462 * disables huge on shm_mnt and all mounts, for emergency use;
464 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
467 #define SHMEM_HUGE_DENY (-1)
468 #define SHMEM_HUGE_FORCE (-2)
470 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
471 /* ifdef here to avoid bloating shmem.o when not necessary */
473 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
475 bool shmem_is_huge(struct vm_area_struct *vma,
476 struct inode *inode, pgoff_t index)
480 if (!S_ISREG(inode->i_mode))
482 if (shmem_huge == SHMEM_HUGE_DENY)
484 if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
485 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
487 if (shmem_huge == SHMEM_HUGE_FORCE)
490 switch (SHMEM_SB(inode->i_sb)->huge) {
491 case SHMEM_HUGE_ALWAYS:
493 case SHMEM_HUGE_WITHIN_SIZE:
494 index = round_up(index + 1, HPAGE_PMD_NR);
495 i_size = round_up(i_size_read(inode), PAGE_SIZE);
496 if (i_size >> PAGE_SHIFT >= index)
499 case SHMEM_HUGE_ADVISE:
500 if (vma && (vma->vm_flags & VM_HUGEPAGE))
508 #if defined(CONFIG_SYSFS)
509 static int shmem_parse_huge(const char *str)
511 if (!strcmp(str, "never"))
512 return SHMEM_HUGE_NEVER;
513 if (!strcmp(str, "always"))
514 return SHMEM_HUGE_ALWAYS;
515 if (!strcmp(str, "within_size"))
516 return SHMEM_HUGE_WITHIN_SIZE;
517 if (!strcmp(str, "advise"))
518 return SHMEM_HUGE_ADVISE;
519 if (!strcmp(str, "deny"))
520 return SHMEM_HUGE_DENY;
521 if (!strcmp(str, "force"))
522 return SHMEM_HUGE_FORCE;
527 #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
528 static const char *shmem_format_huge(int huge)
531 case SHMEM_HUGE_NEVER:
533 case SHMEM_HUGE_ALWAYS:
535 case SHMEM_HUGE_WITHIN_SIZE:
536 return "within_size";
537 case SHMEM_HUGE_ADVISE:
539 case SHMEM_HUGE_DENY:
541 case SHMEM_HUGE_FORCE:
550 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
551 struct shrink_control *sc, unsigned long nr_to_split)
553 LIST_HEAD(list), *pos, *next;
554 LIST_HEAD(to_remove);
556 struct shmem_inode_info *info;
558 unsigned long batch = sc ? sc->nr_to_scan : 128;
561 if (list_empty(&sbinfo->shrinklist))
564 spin_lock(&sbinfo->shrinklist_lock);
565 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
566 info = list_entry(pos, struct shmem_inode_info, shrinklist);
569 inode = igrab(&info->vfs_inode);
571 /* inode is about to be evicted */
573 list_del_init(&info->shrinklist);
577 /* Check if there's anything to gain */
578 if (round_up(inode->i_size, PAGE_SIZE) ==
579 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
580 list_move(&info->shrinklist, &to_remove);
584 list_move(&info->shrinklist, &list);
586 sbinfo->shrinklist_len--;
590 spin_unlock(&sbinfo->shrinklist_lock);
592 list_for_each_safe(pos, next, &to_remove) {
593 info = list_entry(pos, struct shmem_inode_info, shrinklist);
594 inode = &info->vfs_inode;
595 list_del_init(&info->shrinklist);
599 list_for_each_safe(pos, next, &list) {
603 info = list_entry(pos, struct shmem_inode_info, shrinklist);
604 inode = &info->vfs_inode;
606 if (nr_to_split && split >= nr_to_split)
609 index = (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT;
610 folio = filemap_get_folio(inode->i_mapping, index);
614 /* No huge page at the end of the file: nothing to split */
615 if (!folio_test_large(folio)) {
621 * Move the inode on the list back to shrinklist if we failed
622 * to lock the page at this time.
624 * Waiting for the lock may lead to deadlock in the
627 if (!folio_trylock(folio)) {
632 ret = split_huge_page(&folio->page);
636 /* If split failed move the inode on the list back to shrinklist */
642 list_del_init(&info->shrinklist);
646 * Make sure the inode is either on the global list or deleted
647 * from any local list before iput() since it could be deleted
648 * in another thread once we put the inode (then the local list
651 spin_lock(&sbinfo->shrinklist_lock);
652 list_move(&info->shrinklist, &sbinfo->shrinklist);
653 sbinfo->shrinklist_len++;
654 spin_unlock(&sbinfo->shrinklist_lock);
662 static long shmem_unused_huge_scan(struct super_block *sb,
663 struct shrink_control *sc)
665 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
667 if (!READ_ONCE(sbinfo->shrinklist_len))
670 return shmem_unused_huge_shrink(sbinfo, sc, 0);
673 static long shmem_unused_huge_count(struct super_block *sb,
674 struct shrink_control *sc)
676 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
677 return READ_ONCE(sbinfo->shrinklist_len);
679 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
681 #define shmem_huge SHMEM_HUGE_DENY
683 bool shmem_is_huge(struct vm_area_struct *vma,
684 struct inode *inode, pgoff_t index)
689 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
690 struct shrink_control *sc, unsigned long nr_to_split)
694 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
697 * Like filemap_add_folio, but error if expected item has gone.
699 static int shmem_add_to_page_cache(struct folio *folio,
700 struct address_space *mapping,
701 pgoff_t index, void *expected, gfp_t gfp,
702 struct mm_struct *charge_mm)
704 XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
705 long nr = folio_nr_pages(folio);
708 VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
709 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
710 VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
711 VM_BUG_ON(expected && folio_test_large(folio));
713 folio_ref_add(folio, nr);
714 folio->mapping = mapping;
715 folio->index = index;
717 if (!folio_test_swapcache(folio)) {
718 error = mem_cgroup_charge(folio, charge_mm, gfp);
720 if (folio_test_pmd_mappable(folio)) {
721 count_vm_event(THP_FILE_FALLBACK);
722 count_vm_event(THP_FILE_FALLBACK_CHARGE);
727 folio_throttle_swaprate(folio, gfp);
731 if (expected != xas_find_conflict(&xas)) {
732 xas_set_err(&xas, -EEXIST);
735 if (expected && xas_find_conflict(&xas)) {
736 xas_set_err(&xas, -EEXIST);
739 xas_store(&xas, folio);
742 if (folio_test_pmd_mappable(folio)) {
743 count_vm_event(THP_FILE_ALLOC);
744 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr);
746 mapping->nrpages += nr;
747 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);
748 __lruvec_stat_mod_folio(folio, NR_SHMEM, nr);
750 xas_unlock_irq(&xas);
751 } while (xas_nomem(&xas, gfp));
753 if (xas_error(&xas)) {
754 error = xas_error(&xas);
760 folio->mapping = NULL;
761 folio_ref_sub(folio, nr);
766 * Like delete_from_page_cache, but substitutes swap for page.
768 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
770 struct address_space *mapping = page->mapping;
773 VM_BUG_ON_PAGE(PageCompound(page), page);
775 xa_lock_irq(&mapping->i_pages);
776 error = shmem_replace_entry(mapping, page->index, page, radswap);
777 page->mapping = NULL;
779 __dec_lruvec_page_state(page, NR_FILE_PAGES);
780 __dec_lruvec_page_state(page, NR_SHMEM);
781 xa_unlock_irq(&mapping->i_pages);
787 * Remove swap entry from page cache, free the swap and its page cache.
789 static int shmem_free_swap(struct address_space *mapping,
790 pgoff_t index, void *radswap)
794 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
797 free_swap_and_cache(radix_to_swp_entry(radswap));
802 * Determine (in bytes) how many of the shmem object's pages mapped by the
803 * given offsets are swapped out.
805 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
806 * as long as the inode doesn't go away and racy results are not a problem.
808 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
809 pgoff_t start, pgoff_t end)
811 XA_STATE(xas, &mapping->i_pages, start);
813 unsigned long swapped = 0;
816 xas_for_each(&xas, page, end - 1) {
817 if (xas_retry(&xas, page))
819 if (xa_is_value(page))
822 if (need_resched()) {
830 return swapped << PAGE_SHIFT;
834 * Determine (in bytes) how many of the shmem object's pages mapped by the
835 * given vma is swapped out.
837 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
838 * as long as the inode doesn't go away and racy results are not a problem.
840 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
842 struct inode *inode = file_inode(vma->vm_file);
843 struct shmem_inode_info *info = SHMEM_I(inode);
844 struct address_space *mapping = inode->i_mapping;
845 unsigned long swapped;
847 /* Be careful as we don't hold info->lock */
848 swapped = READ_ONCE(info->swapped);
851 * The easier cases are when the shmem object has nothing in swap, or
852 * the vma maps it whole. Then we can simply use the stats that we
858 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
859 return swapped << PAGE_SHIFT;
861 /* Here comes the more involved part */
862 return shmem_partial_swap_usage(mapping, vma->vm_pgoff,
863 vma->vm_pgoff + vma_pages(vma));
867 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
869 void shmem_unlock_mapping(struct address_space *mapping)
871 struct folio_batch fbatch;
874 folio_batch_init(&fbatch);
876 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
878 while (!mapping_unevictable(mapping) &&
879 filemap_get_folios(mapping, &index, ~0UL, &fbatch)) {
880 check_move_unevictable_folios(&fbatch);
881 folio_batch_release(&fbatch);
886 static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
892 * At first avoid shmem_getpage(,,,SGP_READ): that fails
893 * beyond i_size, and reports fallocated pages as holes.
895 folio = __filemap_get_folio(inode->i_mapping, index,
896 FGP_ENTRY | FGP_LOCK, 0);
897 if (!xa_is_value(folio))
900 * But read a page back from swap if any of it is within i_size
901 * (although in some cases this is just a waste of time).
904 shmem_getpage(inode, index, &page, SGP_READ);
905 return page ? page_folio(page) : NULL;
909 * Remove range of pages and swap entries from page cache, and free them.
910 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
912 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
915 struct address_space *mapping = inode->i_mapping;
916 struct shmem_inode_info *info = SHMEM_I(inode);
917 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
918 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
919 struct folio_batch fbatch;
920 pgoff_t indices[PAGEVEC_SIZE];
923 long nr_swaps_freed = 0;
928 end = -1; /* unsigned, so actually very big */
930 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
931 info->fallocend = start;
933 folio_batch_init(&fbatch);
935 while (index < end && find_lock_entries(mapping, index, end - 1,
937 for (i = 0; i < folio_batch_count(&fbatch); i++) {
938 folio = fbatch.folios[i];
942 if (xa_is_value(folio)) {
945 nr_swaps_freed += !shmem_free_swap(mapping,
949 index += folio_nr_pages(folio) - 1;
951 if (!unfalloc || !folio_test_uptodate(folio))
952 truncate_inode_folio(mapping, folio);
955 folio_batch_remove_exceptionals(&fbatch);
956 folio_batch_release(&fbatch);
961 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
962 folio = shmem_get_partial_folio(inode, lstart >> PAGE_SHIFT);
964 same_folio = lend < folio_pos(folio) + folio_size(folio);
965 folio_mark_dirty(folio);
966 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
967 start = folio->index + folio_nr_pages(folio);
977 folio = shmem_get_partial_folio(inode, lend >> PAGE_SHIFT);
979 folio_mark_dirty(folio);
980 if (!truncate_inode_partial_folio(folio, lstart, lend))
987 while (index < end) {
990 if (!find_get_entries(mapping, index, end - 1, &fbatch,
992 /* If all gone or hole-punch or unfalloc, we're done */
993 if (index == start || end != -1)
995 /* But if truncating, restart to make sure all gone */
999 for (i = 0; i < folio_batch_count(&fbatch); i++) {
1000 folio = fbatch.folios[i];
1003 if (xa_is_value(folio)) {
1006 if (shmem_free_swap(mapping, index, folio)) {
1007 /* Swap was replaced by page: retry */
1017 if (!unfalloc || !folio_test_uptodate(folio)) {
1018 if (folio_mapping(folio) != mapping) {
1019 /* Page was replaced by swap: retry */
1020 folio_unlock(folio);
1024 VM_BUG_ON_FOLIO(folio_test_writeback(folio),
1026 truncate_inode_folio(mapping, folio);
1028 index = folio->index + folio_nr_pages(folio) - 1;
1029 folio_unlock(folio);
1031 folio_batch_remove_exceptionals(&fbatch);
1032 folio_batch_release(&fbatch);
1036 spin_lock_irq(&info->lock);
1037 info->swapped -= nr_swaps_freed;
1038 shmem_recalc_inode(inode);
1039 spin_unlock_irq(&info->lock);
1042 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1044 shmem_undo_range(inode, lstart, lend, false);
1045 inode->i_ctime = inode->i_mtime = current_time(inode);
1047 EXPORT_SYMBOL_GPL(shmem_truncate_range);
1049 static int shmem_getattr(struct user_namespace *mnt_userns,
1050 const struct path *path, struct kstat *stat,
1051 u32 request_mask, unsigned int query_flags)
1053 struct inode *inode = path->dentry->d_inode;
1054 struct shmem_inode_info *info = SHMEM_I(inode);
1056 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
1057 spin_lock_irq(&info->lock);
1058 shmem_recalc_inode(inode);
1059 spin_unlock_irq(&info->lock);
1061 if (info->fsflags & FS_APPEND_FL)
1062 stat->attributes |= STATX_ATTR_APPEND;
1063 if (info->fsflags & FS_IMMUTABLE_FL)
1064 stat->attributes |= STATX_ATTR_IMMUTABLE;
1065 if (info->fsflags & FS_NODUMP_FL)
1066 stat->attributes |= STATX_ATTR_NODUMP;
1067 stat->attributes_mask |= (STATX_ATTR_APPEND |
1068 STATX_ATTR_IMMUTABLE |
1070 generic_fillattr(&init_user_ns, inode, stat);
1072 if (shmem_is_huge(NULL, inode, 0))
1073 stat->blksize = HPAGE_PMD_SIZE;
1075 if (request_mask & STATX_BTIME) {
1076 stat->result_mask |= STATX_BTIME;
1077 stat->btime.tv_sec = info->i_crtime.tv_sec;
1078 stat->btime.tv_nsec = info->i_crtime.tv_nsec;
1084 static int shmem_setattr(struct user_namespace *mnt_userns,
1085 struct dentry *dentry, struct iattr *attr)
1087 struct inode *inode = d_inode(dentry);
1088 struct shmem_inode_info *info = SHMEM_I(inode);
1091 error = setattr_prepare(&init_user_ns, dentry, attr);
1095 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1096 loff_t oldsize = inode->i_size;
1097 loff_t newsize = attr->ia_size;
1099 /* protected by i_rwsem */
1100 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1101 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1104 if (newsize != oldsize) {
1105 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1109 i_size_write(inode, newsize);
1110 inode->i_ctime = inode->i_mtime = current_time(inode);
1112 if (newsize <= oldsize) {
1113 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1114 if (oldsize > holebegin)
1115 unmap_mapping_range(inode->i_mapping,
1118 shmem_truncate_range(inode,
1119 newsize, (loff_t)-1);
1120 /* unmap again to remove racily COWed private pages */
1121 if (oldsize > holebegin)
1122 unmap_mapping_range(inode->i_mapping,
1127 setattr_copy(&init_user_ns, inode, attr);
1128 if (attr->ia_valid & ATTR_MODE)
1129 error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
1133 static void shmem_evict_inode(struct inode *inode)
1135 struct shmem_inode_info *info = SHMEM_I(inode);
1136 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1138 if (shmem_mapping(inode->i_mapping)) {
1139 shmem_unacct_size(info->flags, inode->i_size);
1141 mapping_set_exiting(inode->i_mapping);
1142 shmem_truncate_range(inode, 0, (loff_t)-1);
1143 if (!list_empty(&info->shrinklist)) {
1144 spin_lock(&sbinfo->shrinklist_lock);
1145 if (!list_empty(&info->shrinklist)) {
1146 list_del_init(&info->shrinklist);
1147 sbinfo->shrinklist_len--;
1149 spin_unlock(&sbinfo->shrinklist_lock);
1151 while (!list_empty(&info->swaplist)) {
1152 /* Wait while shmem_unuse() is scanning this inode... */
1153 wait_var_event(&info->stop_eviction,
1154 !atomic_read(&info->stop_eviction));
1155 mutex_lock(&shmem_swaplist_mutex);
1156 /* ...but beware of the race if we peeked too early */
1157 if (!atomic_read(&info->stop_eviction))
1158 list_del_init(&info->swaplist);
1159 mutex_unlock(&shmem_swaplist_mutex);
1163 simple_xattrs_free(&info->xattrs);
1164 WARN_ON(inode->i_blocks);
1165 shmem_free_inode(inode->i_sb);
1169 static int shmem_find_swap_entries(struct address_space *mapping,
1170 pgoff_t start, struct folio_batch *fbatch,
1171 pgoff_t *indices, unsigned int type)
1173 XA_STATE(xas, &mapping->i_pages, start);
1174 struct folio *folio;
1178 xas_for_each(&xas, folio, ULONG_MAX) {
1179 if (xas_retry(&xas, folio))
1182 if (!xa_is_value(folio))
1185 entry = radix_to_swp_entry(folio);
1187 * swapin error entries can be found in the mapping. But they're
1188 * deliberately ignored here as we've done everything we can do.
1190 if (swp_type(entry) != type)
1193 indices[folio_batch_count(fbatch)] = xas.xa_index;
1194 if (!folio_batch_add(fbatch, folio))
1197 if (need_resched()) {
1204 return xas.xa_index;
1208 * Move the swapped pages for an inode to page cache. Returns the count
1209 * of pages swapped in, or the error in case of failure.
1211 static int shmem_unuse_swap_entries(struct inode *inode,
1212 struct folio_batch *fbatch, pgoff_t *indices)
1217 struct address_space *mapping = inode->i_mapping;
1219 for (i = 0; i < folio_batch_count(fbatch); i++) {
1220 struct folio *folio = fbatch->folios[i];
1222 if (!xa_is_value(folio))
1224 error = shmem_swapin_folio(inode, indices[i],
1226 mapping_gfp_mask(mapping),
1229 folio_unlock(folio);
1233 if (error == -ENOMEM)
1237 return error ? error : ret;
1241 * If swap found in inode, free it and move page from swapcache to filecache.
1243 static int shmem_unuse_inode(struct inode *inode, unsigned int type)
1245 struct address_space *mapping = inode->i_mapping;
1247 struct folio_batch fbatch;
1248 pgoff_t indices[PAGEVEC_SIZE];
1252 folio_batch_init(&fbatch);
1253 shmem_find_swap_entries(mapping, start, &fbatch, indices, type);
1254 if (folio_batch_count(&fbatch) == 0) {
1259 ret = shmem_unuse_swap_entries(inode, &fbatch, indices);
1263 start = indices[folio_batch_count(&fbatch) - 1];
1270 * Read all the shared memory data that resides in the swap
1271 * device 'type' back into memory, so the swap device can be
1274 int shmem_unuse(unsigned int type)
1276 struct shmem_inode_info *info, *next;
1279 if (list_empty(&shmem_swaplist))
1282 mutex_lock(&shmem_swaplist_mutex);
1283 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1284 if (!info->swapped) {
1285 list_del_init(&info->swaplist);
1289 * Drop the swaplist mutex while searching the inode for swap;
1290 * but before doing so, make sure shmem_evict_inode() will not
1291 * remove placeholder inode from swaplist, nor let it be freed
1292 * (igrab() would protect from unlink, but not from unmount).
1294 atomic_inc(&info->stop_eviction);
1295 mutex_unlock(&shmem_swaplist_mutex);
1297 error = shmem_unuse_inode(&info->vfs_inode, type);
1300 mutex_lock(&shmem_swaplist_mutex);
1301 next = list_next_entry(info, swaplist);
1303 list_del_init(&info->swaplist);
1304 if (atomic_dec_and_test(&info->stop_eviction))
1305 wake_up_var(&info->stop_eviction);
1309 mutex_unlock(&shmem_swaplist_mutex);
1315 * Move the page from the page cache to the swap cache.
1317 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1319 struct folio *folio = page_folio(page);
1320 struct shmem_inode_info *info;
1321 struct address_space *mapping;
1322 struct inode *inode;
1327 * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or
1328 * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
1329 * and its shmem_writeback() needs them to be split when swapping.
1331 if (PageTransCompound(page)) {
1332 /* Ensure the subpages are still dirty */
1334 if (split_huge_page(page) < 0)
1336 ClearPageDirty(page);
1339 BUG_ON(!PageLocked(page));
1340 mapping = page->mapping;
1341 index = page->index;
1342 inode = mapping->host;
1343 info = SHMEM_I(inode);
1344 if (info->flags & VM_LOCKED)
1346 if (!total_swap_pages)
1350 * Our capabilities prevent regular writeback or sync from ever calling
1351 * shmem_writepage; but a stacking filesystem might use ->writepage of
1352 * its underlying filesystem, in which case tmpfs should write out to
1353 * swap only in response to memory pressure, and not for the writeback
1356 if (!wbc->for_reclaim) {
1357 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1362 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1363 * value into swapfile.c, the only way we can correctly account for a
1364 * fallocated page arriving here is now to initialize it and write it.
1366 * That's okay for a page already fallocated earlier, but if we have
1367 * not yet completed the fallocation, then (a) we want to keep track
1368 * of this page in case we have to undo it, and (b) it may not be a
1369 * good idea to continue anyway, once we're pushing into swap. So
1370 * reactivate the page, and let shmem_fallocate() quit when too many.
1372 if (!PageUptodate(page)) {
1373 if (inode->i_private) {
1374 struct shmem_falloc *shmem_falloc;
1375 spin_lock(&inode->i_lock);
1376 shmem_falloc = inode->i_private;
1378 !shmem_falloc->waitq &&
1379 index >= shmem_falloc->start &&
1380 index < shmem_falloc->next)
1381 shmem_falloc->nr_unswapped++;
1383 shmem_falloc = NULL;
1384 spin_unlock(&inode->i_lock);
1388 clear_highpage(page);
1389 flush_dcache_page(page);
1390 SetPageUptodate(page);
1393 swap = folio_alloc_swap(folio);
1398 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1399 * if it's not already there. Do it now before the page is
1400 * moved to swap cache, when its pagelock no longer protects
1401 * the inode from eviction. But don't unlock the mutex until
1402 * we've incremented swapped, because shmem_unuse_inode() will
1403 * prune a !swapped inode from the swaplist under this mutex.
1405 mutex_lock(&shmem_swaplist_mutex);
1406 if (list_empty(&info->swaplist))
1407 list_add(&info->swaplist, &shmem_swaplist);
1409 if (add_to_swap_cache(page, swap,
1410 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1412 spin_lock_irq(&info->lock);
1413 shmem_recalc_inode(inode);
1415 spin_unlock_irq(&info->lock);
1417 swap_shmem_alloc(swap);
1418 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1420 mutex_unlock(&shmem_swaplist_mutex);
1421 BUG_ON(page_mapped(page));
1422 swap_writepage(page, wbc);
1426 mutex_unlock(&shmem_swaplist_mutex);
1427 put_swap_page(page, swap);
1429 set_page_dirty(page);
1430 if (wbc->for_reclaim)
1431 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1436 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1437 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1441 if (!mpol || mpol->mode == MPOL_DEFAULT)
1442 return; /* show nothing */
1444 mpol_to_str(buffer, sizeof(buffer), mpol);
1446 seq_printf(seq, ",mpol=%s", buffer);
1449 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1451 struct mempolicy *mpol = NULL;
1453 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1454 mpol = sbinfo->mpol;
1456 raw_spin_unlock(&sbinfo->stat_lock);
1460 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1461 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1464 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1468 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1470 #define vm_policy vm_private_data
1473 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1474 struct shmem_inode_info *info, pgoff_t index)
1476 /* Create a pseudo vma that just contains the policy */
1477 vma_init(vma, NULL);
1478 /* Bias interleave by inode number to distribute better across nodes */
1479 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1480 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1483 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1485 /* Drop reference taken by mpol_shared_policy_lookup() */
1486 mpol_cond_put(vma->vm_policy);
1489 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1490 struct shmem_inode_info *info, pgoff_t index)
1492 struct vm_area_struct pvma;
1494 struct vm_fault vmf = {
1498 shmem_pseudo_vma_init(&pvma, info, index);
1499 page = swap_cluster_readahead(swap, gfp, &vmf);
1500 shmem_pseudo_vma_destroy(&pvma);
1506 * Make sure huge_gfp is always more limited than limit_gfp.
1507 * Some of the flags set permissions, while others set limitations.
1509 static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1511 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1512 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1513 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1514 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1516 /* Allow allocations only from the originally specified zones. */
1517 result |= zoneflags;
1520 * Minimize the result gfp by taking the union with the deny flags,
1521 * and the intersection of the allow flags.
1523 result |= (limit_gfp & denyflags);
1524 result |= (huge_gfp & limit_gfp) & allowflags;
1529 static struct folio *shmem_alloc_hugefolio(gfp_t gfp,
1530 struct shmem_inode_info *info, pgoff_t index)
1532 struct vm_area_struct pvma;
1533 struct address_space *mapping = info->vfs_inode.i_mapping;
1535 struct folio *folio;
1537 hindex = round_down(index, HPAGE_PMD_NR);
1538 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1542 shmem_pseudo_vma_init(&pvma, info, hindex);
1543 folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, &pvma, 0, true);
1544 shmem_pseudo_vma_destroy(&pvma);
1546 count_vm_event(THP_FILE_FALLBACK);
1550 static struct folio *shmem_alloc_folio(gfp_t gfp,
1551 struct shmem_inode_info *info, pgoff_t index)
1553 struct vm_area_struct pvma;
1554 struct folio *folio;
1556 shmem_pseudo_vma_init(&pvma, info, index);
1557 folio = vma_alloc_folio(gfp, 0, &pvma, 0, false);
1558 shmem_pseudo_vma_destroy(&pvma);
1563 static struct page *shmem_alloc_page(gfp_t gfp,
1564 struct shmem_inode_info *info, pgoff_t index)
1566 return &shmem_alloc_folio(gfp, info, index)->page;
1569 static struct folio *shmem_alloc_and_acct_folio(gfp_t gfp, struct inode *inode,
1570 pgoff_t index, bool huge)
1572 struct shmem_inode_info *info = SHMEM_I(inode);
1573 struct folio *folio;
1577 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1579 nr = huge ? HPAGE_PMD_NR : 1;
1581 if (!shmem_inode_acct_block(inode, nr))
1585 folio = shmem_alloc_hugefolio(gfp, info, index);
1587 folio = shmem_alloc_folio(gfp, info, index);
1589 __folio_set_locked(folio);
1590 __folio_set_swapbacked(folio);
1595 shmem_inode_unacct_blocks(inode, nr);
1597 return ERR_PTR(err);
1601 * When a page is moved from swapcache to shmem filecache (either by the
1602 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1603 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1604 * ignorance of the mapping it belongs to. If that mapping has special
1605 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1606 * we may need to copy to a suitable page before moving to filecache.
1608 * In a future release, this may well be extended to respect cpuset and
1609 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1610 * but for now it is a simple matter of zone.
1612 static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
1614 return folio_zonenum(folio) > gfp_zone(gfp);
1617 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1618 struct shmem_inode_info *info, pgoff_t index)
1620 struct page *oldpage, *newpage;
1621 struct folio *old, *new;
1622 struct address_space *swap_mapping;
1628 entry.val = page_private(oldpage);
1629 swap_index = swp_offset(entry);
1630 swap_mapping = page_mapping(oldpage);
1633 * We have arrived here because our zones are constrained, so don't
1634 * limit chance of success by further cpuset and node constraints.
1636 gfp &= ~GFP_CONSTRAINT_MASK;
1637 newpage = shmem_alloc_page(gfp, info, index);
1642 copy_highpage(newpage, oldpage);
1643 flush_dcache_page(newpage);
1645 __SetPageLocked(newpage);
1646 __SetPageSwapBacked(newpage);
1647 SetPageUptodate(newpage);
1648 set_page_private(newpage, entry.val);
1649 SetPageSwapCache(newpage);
1652 * Our caller will very soon move newpage out of swapcache, but it's
1653 * a nice clean interface for us to replace oldpage by newpage there.
1655 xa_lock_irq(&swap_mapping->i_pages);
1656 error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
1658 old = page_folio(oldpage);
1659 new = page_folio(newpage);
1660 mem_cgroup_migrate(old, new);
1661 __inc_lruvec_page_state(newpage, NR_FILE_PAGES);
1662 __dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
1664 xa_unlock_irq(&swap_mapping->i_pages);
1666 if (unlikely(error)) {
1668 * Is this possible? I think not, now that our callers check
1669 * both PageSwapCache and page_private after getting page lock;
1670 * but be defensive. Reverse old to newpage for clear and free.
1674 lru_cache_add(newpage);
1678 ClearPageSwapCache(oldpage);
1679 set_page_private(oldpage, 0);
1681 unlock_page(oldpage);
1687 static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
1688 struct folio *folio, swp_entry_t swap)
1690 struct address_space *mapping = inode->i_mapping;
1691 struct shmem_inode_info *info = SHMEM_I(inode);
1692 swp_entry_t swapin_error;
1695 swapin_error = make_swapin_error_entry(&folio->page);
1696 old = xa_cmpxchg_irq(&mapping->i_pages, index,
1697 swp_to_radix_entry(swap),
1698 swp_to_radix_entry(swapin_error), 0);
1699 if (old != swp_to_radix_entry(swap))
1702 folio_wait_writeback(folio);
1703 delete_from_swap_cache(folio);
1704 spin_lock_irq(&info->lock);
1706 * Don't treat swapin error folio as alloced. Otherwise inode->i_blocks won't
1707 * be 0 when inode is released and thus trigger WARN_ON(inode->i_blocks) in
1708 * shmem_evict_inode.
1712 shmem_recalc_inode(inode);
1713 spin_unlock_irq(&info->lock);
1718 * Swap in the folio pointed to by *foliop.
1719 * Caller has to make sure that *foliop contains a valid swapped folio.
1720 * Returns 0 and the folio in foliop if success. On failure, returns the
1721 * error code and NULL in *foliop.
1723 static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
1724 struct folio **foliop, enum sgp_type sgp,
1725 gfp_t gfp, struct vm_area_struct *vma,
1726 vm_fault_t *fault_type)
1728 struct address_space *mapping = inode->i_mapping;
1729 struct shmem_inode_info *info = SHMEM_I(inode);
1730 struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
1732 struct folio *folio = NULL;
1736 VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
1737 swap = radix_to_swp_entry(*foliop);
1740 if (is_swapin_error_entry(swap))
1743 /* Look it up and read it in.. */
1744 page = lookup_swap_cache(swap, NULL, 0);
1746 /* Or update major stats only when swapin succeeds?? */
1748 *fault_type |= VM_FAULT_MAJOR;
1749 count_vm_event(PGMAJFAULT);
1750 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1752 /* Here we actually start the io */
1753 page = shmem_swapin(swap, gfp, info, index);
1759 folio = page_folio(page);
1761 /* We have to do this with folio locked to prevent races */
1763 if (!folio_test_swapcache(folio) ||
1764 folio_swap_entry(folio).val != swap.val ||
1765 !shmem_confirm_swap(mapping, index, swap)) {
1769 if (!folio_test_uptodate(folio)) {
1773 folio_wait_writeback(folio);
1776 * Some architectures may have to restore extra metadata to the
1777 * folio after reading from swap.
1779 arch_swap_restore(swap, folio);
1781 if (shmem_should_replace_folio(folio, gfp)) {
1782 error = shmem_replace_page(&page, gfp, info, index);
1787 error = shmem_add_to_page_cache(folio, mapping, index,
1788 swp_to_radix_entry(swap), gfp,
1793 spin_lock_irq(&info->lock);
1795 shmem_recalc_inode(inode);
1796 spin_unlock_irq(&info->lock);
1798 if (sgp == SGP_WRITE)
1799 folio_mark_accessed(folio);
1801 delete_from_swap_cache(folio);
1802 folio_mark_dirty(folio);
1808 if (!shmem_confirm_swap(mapping, index, swap))
1811 shmem_set_folio_swapin_error(inode, index, folio, swap);
1814 folio_unlock(folio);
1822 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1824 * If we allocate a new one we do not mark it dirty. That's up to the
1825 * vm. If we swap it in we mark it dirty since we also free the swap
1826 * entry since a page cannot live in both the swap and page cache.
1828 * vma, vmf, and fault_type are only supplied by shmem_fault:
1829 * otherwise they are NULL.
1831 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1832 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1833 struct vm_area_struct *vma, struct vm_fault *vmf,
1834 vm_fault_t *fault_type)
1836 struct address_space *mapping = inode->i_mapping;
1837 struct shmem_inode_info *info = SHMEM_I(inode);
1838 struct shmem_sb_info *sbinfo;
1839 struct mm_struct *charge_mm;
1840 struct folio *folio;
1841 pgoff_t hindex = index;
1847 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1850 if (sgp <= SGP_CACHE &&
1851 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1855 sbinfo = SHMEM_SB(inode->i_sb);
1856 charge_mm = vma ? vma->vm_mm : NULL;
1858 folio = __filemap_get_folio(mapping, index, FGP_ENTRY | FGP_LOCK, 0);
1859 if (folio && vma && userfaultfd_minor(vma)) {
1860 if (!xa_is_value(folio)) {
1861 folio_unlock(folio);
1864 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
1868 if (xa_is_value(folio)) {
1869 error = shmem_swapin_folio(inode, index, &folio,
1870 sgp, gfp, vma, fault_type);
1871 if (error == -EEXIST)
1874 *pagep = &folio->page;
1879 hindex = folio->index;
1880 if (sgp == SGP_WRITE)
1881 folio_mark_accessed(folio);
1882 if (folio_test_uptodate(folio))
1884 /* fallocated page */
1885 if (sgp != SGP_READ)
1887 folio_unlock(folio);
1892 * SGP_READ: succeed on hole, with NULL page, letting caller zero.
1893 * SGP_NOALLOC: fail on hole, with NULL page, letting caller fail.
1896 if (sgp == SGP_READ)
1898 if (sgp == SGP_NOALLOC)
1902 * Fast cache lookup and swap lookup did not find it: allocate.
1905 if (vma && userfaultfd_missing(vma)) {
1906 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1910 if (!shmem_is_huge(vma, inode, index))
1913 huge_gfp = vma_thp_gfp_mask(vma);
1914 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
1915 folio = shmem_alloc_and_acct_folio(huge_gfp, inode, index, true);
1916 if (IS_ERR(folio)) {
1918 folio = shmem_alloc_and_acct_folio(gfp, inode, index, false);
1920 if (IS_ERR(folio)) {
1923 error = PTR_ERR(folio);
1925 if (error != -ENOSPC)
1928 * Try to reclaim some space by splitting a huge page
1929 * beyond i_size on the filesystem.
1934 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1935 if (ret == SHRINK_STOP)
1943 hindex = round_down(index, folio_nr_pages(folio));
1945 if (sgp == SGP_WRITE)
1946 __folio_set_referenced(folio);
1948 error = shmem_add_to_page_cache(folio, mapping, hindex,
1949 NULL, gfp & GFP_RECLAIM_MASK,
1953 folio_add_lru(folio);
1955 spin_lock_irq(&info->lock);
1956 info->alloced += folio_nr_pages(folio);
1957 inode->i_blocks += (blkcnt_t)BLOCKS_PER_PAGE << folio_order(folio);
1958 shmem_recalc_inode(inode);
1959 spin_unlock_irq(&info->lock);
1962 if (folio_test_pmd_mappable(folio) &&
1963 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1964 hindex + HPAGE_PMD_NR - 1) {
1966 * Part of the huge page is beyond i_size: subject
1967 * to shrink under memory pressure.
1969 spin_lock(&sbinfo->shrinklist_lock);
1971 * _careful to defend against unlocked access to
1972 * ->shrink_list in shmem_unused_huge_shrink()
1974 if (list_empty_careful(&info->shrinklist)) {
1975 list_add_tail(&info->shrinklist,
1976 &sbinfo->shrinklist);
1977 sbinfo->shrinklist_len++;
1979 spin_unlock(&sbinfo->shrinklist_lock);
1983 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1985 if (sgp == SGP_FALLOC)
1989 * Let SGP_WRITE caller clear ends if write does not fill page;
1990 * but SGP_FALLOC on a page fallocated earlier must initialize
1991 * it now, lest undo on failure cancel our earlier guarantee.
1993 if (sgp != SGP_WRITE && !folio_test_uptodate(folio)) {
1994 long i, n = folio_nr_pages(folio);
1996 for (i = 0; i < n; i++)
1997 clear_highpage(folio_page(folio, i));
1998 flush_dcache_folio(folio);
1999 folio_mark_uptodate(folio);
2002 /* Perhaps the file has been truncated since we checked */
2003 if (sgp <= SGP_CACHE &&
2004 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
2006 folio_clear_dirty(folio);
2007 filemap_remove_folio(folio);
2008 spin_lock_irq(&info->lock);
2009 shmem_recalc_inode(inode);
2010 spin_unlock_irq(&info->lock);
2016 *pagep = folio_page(folio, index - hindex);
2023 shmem_inode_unacct_blocks(inode, folio_nr_pages(folio));
2025 if (folio_test_large(folio)) {
2026 folio_unlock(folio);
2032 folio_unlock(folio);
2035 if (error == -ENOSPC && !once++) {
2036 spin_lock_irq(&info->lock);
2037 shmem_recalc_inode(inode);
2038 spin_unlock_irq(&info->lock);
2041 if (error == -EEXIST)
2047 * This is like autoremove_wake_function, but it removes the wait queue
2048 * entry unconditionally - even if something else had already woken the
2051 static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
2053 int ret = default_wake_function(wait, mode, sync, key);
2054 list_del_init(&wait->entry);
2058 static vm_fault_t shmem_fault(struct vm_fault *vmf)
2060 struct vm_area_struct *vma = vmf->vma;
2061 struct inode *inode = file_inode(vma->vm_file);
2062 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2064 vm_fault_t ret = VM_FAULT_LOCKED;
2067 * Trinity finds that probing a hole which tmpfs is punching can
2068 * prevent the hole-punch from ever completing: which in turn
2069 * locks writers out with its hold on i_rwsem. So refrain from
2070 * faulting pages into the hole while it's being punched. Although
2071 * shmem_undo_range() does remove the additions, it may be unable to
2072 * keep up, as each new page needs its own unmap_mapping_range() call,
2073 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2075 * It does not matter if we sometimes reach this check just before the
2076 * hole-punch begins, so that one fault then races with the punch:
2077 * we just need to make racing faults a rare case.
2079 * The implementation below would be much simpler if we just used a
2080 * standard mutex or completion: but we cannot take i_rwsem in fault,
2081 * and bloating every shmem inode for this unlikely case would be sad.
2083 if (unlikely(inode->i_private)) {
2084 struct shmem_falloc *shmem_falloc;
2086 spin_lock(&inode->i_lock);
2087 shmem_falloc = inode->i_private;
2089 shmem_falloc->waitq &&
2090 vmf->pgoff >= shmem_falloc->start &&
2091 vmf->pgoff < shmem_falloc->next) {
2093 wait_queue_head_t *shmem_falloc_waitq;
2094 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2096 ret = VM_FAULT_NOPAGE;
2097 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2099 ret = VM_FAULT_RETRY;
2101 shmem_falloc_waitq = shmem_falloc->waitq;
2102 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2103 TASK_UNINTERRUPTIBLE);
2104 spin_unlock(&inode->i_lock);
2108 * shmem_falloc_waitq points into the shmem_fallocate()
2109 * stack of the hole-punching task: shmem_falloc_waitq
2110 * is usually invalid by the time we reach here, but
2111 * finish_wait() does not dereference it in that case;
2112 * though i_lock needed lest racing with wake_up_all().
2114 spin_lock(&inode->i_lock);
2115 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2116 spin_unlock(&inode->i_lock);
2122 spin_unlock(&inode->i_lock);
2125 err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE,
2126 gfp, vma, vmf, &ret);
2128 return vmf_error(err);
2132 unsigned long shmem_get_unmapped_area(struct file *file,
2133 unsigned long uaddr, unsigned long len,
2134 unsigned long pgoff, unsigned long flags)
2136 unsigned long (*get_area)(struct file *,
2137 unsigned long, unsigned long, unsigned long, unsigned long);
2139 unsigned long offset;
2140 unsigned long inflated_len;
2141 unsigned long inflated_addr;
2142 unsigned long inflated_offset;
2144 if (len > TASK_SIZE)
2147 get_area = current->mm->get_unmapped_area;
2148 addr = get_area(file, uaddr, len, pgoff, flags);
2150 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2152 if (IS_ERR_VALUE(addr))
2154 if (addr & ~PAGE_MASK)
2156 if (addr > TASK_SIZE - len)
2159 if (shmem_huge == SHMEM_HUGE_DENY)
2161 if (len < HPAGE_PMD_SIZE)
2163 if (flags & MAP_FIXED)
2166 * Our priority is to support MAP_SHARED mapped hugely;
2167 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2168 * But if caller specified an address hint and we allocated area there
2169 * successfully, respect that as before.
2174 if (shmem_huge != SHMEM_HUGE_FORCE) {
2175 struct super_block *sb;
2178 VM_BUG_ON(file->f_op != &shmem_file_operations);
2179 sb = file_inode(file)->i_sb;
2182 * Called directly from mm/mmap.c, or drivers/char/mem.c
2183 * for "/dev/zero", to create a shared anonymous object.
2185 if (IS_ERR(shm_mnt))
2187 sb = shm_mnt->mnt_sb;
2189 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2193 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2194 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2196 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2199 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2200 if (inflated_len > TASK_SIZE)
2202 if (inflated_len < len)
2205 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2206 if (IS_ERR_VALUE(inflated_addr))
2208 if (inflated_addr & ~PAGE_MASK)
2211 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2212 inflated_addr += offset - inflated_offset;
2213 if (inflated_offset > offset)
2214 inflated_addr += HPAGE_PMD_SIZE;
2216 if (inflated_addr > TASK_SIZE - len)
2218 return inflated_addr;
2222 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2224 struct inode *inode = file_inode(vma->vm_file);
2225 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2228 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2231 struct inode *inode = file_inode(vma->vm_file);
2234 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2235 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2239 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2241 struct inode *inode = file_inode(file);
2242 struct shmem_inode_info *info = SHMEM_I(inode);
2243 int retval = -ENOMEM;
2246 * What serializes the accesses to info->flags?
2247 * ipc_lock_object() when called from shmctl_do_lock(),
2248 * no serialization needed when called from shm_destroy().
2250 if (lock && !(info->flags & VM_LOCKED)) {
2251 if (!user_shm_lock(inode->i_size, ucounts))
2253 info->flags |= VM_LOCKED;
2254 mapping_set_unevictable(file->f_mapping);
2256 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2257 user_shm_unlock(inode->i_size, ucounts);
2258 info->flags &= ~VM_LOCKED;
2259 mapping_clear_unevictable(file->f_mapping);
2267 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2269 struct shmem_inode_info *info = SHMEM_I(file_inode(file));
2272 ret = seal_check_future_write(info->seals, vma);
2276 /* arm64 - allow memory tagging on RAM-based files */
2277 vma->vm_flags |= VM_MTE_ALLOWED;
2279 file_accessed(file);
2280 vma->vm_ops = &shmem_vm_ops;
2284 /* Mask out flags that are inappropriate for the given type of inode. */
2285 static unsigned shmem_mask_flags(umode_t mode, __u32 flags)
2289 else if (S_ISREG(mode))
2290 return flags & SHMEM_REG_FLMASK;
2292 return flags & SHMEM_OTHER_FLMASK;
2295 static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir,
2296 umode_t mode, dev_t dev, unsigned long flags)
2298 struct inode *inode;
2299 struct shmem_inode_info *info;
2300 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2303 if (shmem_reserve_inode(sb, &ino))
2306 inode = new_inode(sb);
2309 inode_init_owner(&init_user_ns, inode, dir, mode);
2310 inode->i_blocks = 0;
2311 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2312 inode->i_generation = prandom_u32();
2313 info = SHMEM_I(inode);
2314 memset(info, 0, (char *)inode - (char *)info);
2315 spin_lock_init(&info->lock);
2316 atomic_set(&info->stop_eviction, 0);
2317 info->seals = F_SEAL_SEAL;
2318 info->flags = flags & VM_NORESERVE;
2319 info->i_crtime = inode->i_mtime;
2320 info->fsflags = (dir == NULL) ? 0 :
2321 SHMEM_I(dir)->fsflags & SHMEM_FL_INHERITED;
2322 info->fsflags = shmem_mask_flags(mode, info->fsflags);
2323 INIT_LIST_HEAD(&info->shrinklist);
2324 INIT_LIST_HEAD(&info->swaplist);
2325 simple_xattrs_init(&info->xattrs);
2326 cache_no_acl(inode);
2327 mapping_set_large_folios(inode->i_mapping);
2329 switch (mode & S_IFMT) {
2331 inode->i_op = &shmem_special_inode_operations;
2332 init_special_inode(inode, mode, dev);
2335 inode->i_mapping->a_ops = &shmem_aops;
2336 inode->i_op = &shmem_inode_operations;
2337 inode->i_fop = &shmem_file_operations;
2338 mpol_shared_policy_init(&info->policy,
2339 shmem_get_sbmpol(sbinfo));
2343 /* Some things misbehave if size == 0 on a directory */
2344 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2345 inode->i_op = &shmem_dir_inode_operations;
2346 inode->i_fop = &simple_dir_operations;
2350 * Must not load anything in the rbtree,
2351 * mpol_free_shared_policy will not be called.
2353 mpol_shared_policy_init(&info->policy, NULL);
2357 lockdep_annotate_inode_mutex_key(inode);
2359 shmem_free_inode(sb);
2363 #ifdef CONFIG_USERFAULTFD
2364 int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2366 struct vm_area_struct *dst_vma,
2367 unsigned long dst_addr,
2368 unsigned long src_addr,
2369 bool zeropage, bool wp_copy,
2370 struct page **pagep)
2372 struct inode *inode = file_inode(dst_vma->vm_file);
2373 struct shmem_inode_info *info = SHMEM_I(inode);
2374 struct address_space *mapping = inode->i_mapping;
2375 gfp_t gfp = mapping_gfp_mask(mapping);
2376 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2378 struct folio *folio;
2383 if (!shmem_inode_acct_block(inode, 1)) {
2385 * We may have got a page, returned -ENOENT triggering a retry,
2386 * and now we find ourselves with -ENOMEM. Release the page, to
2387 * avoid a BUG_ON in our caller.
2389 if (unlikely(*pagep)) {
2398 page = shmem_alloc_page(gfp, info, pgoff);
2400 goto out_unacct_blocks;
2402 if (!zeropage) { /* COPY */
2403 page_kaddr = kmap_atomic(page);
2404 ret = copy_from_user(page_kaddr,
2405 (const void __user *)src_addr,
2407 kunmap_atomic(page_kaddr);
2409 /* fallback to copy_from_user outside mmap_lock */
2410 if (unlikely(ret)) {
2413 /* don't free the page */
2414 goto out_unacct_blocks;
2417 flush_dcache_page(page);
2418 } else { /* ZEROPAGE */
2419 clear_user_highpage(page, dst_addr);
2426 VM_BUG_ON(PageLocked(page));
2427 VM_BUG_ON(PageSwapBacked(page));
2428 __SetPageLocked(page);
2429 __SetPageSwapBacked(page);
2430 __SetPageUptodate(page);
2433 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2434 if (unlikely(pgoff >= max_off))
2437 folio = page_folio(page);
2438 ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL,
2439 gfp & GFP_RECLAIM_MASK, dst_mm);
2443 ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
2444 page, true, wp_copy);
2446 goto out_delete_from_cache;
2448 spin_lock_irq(&info->lock);
2450 inode->i_blocks += BLOCKS_PER_PAGE;
2451 shmem_recalc_inode(inode);
2452 spin_unlock_irq(&info->lock);
2456 out_delete_from_cache:
2457 delete_from_page_cache(page);
2462 shmem_inode_unacct_blocks(inode, 1);
2465 #endif /* CONFIG_USERFAULTFD */
2468 static const struct inode_operations shmem_symlink_inode_operations;
2469 static const struct inode_operations shmem_short_symlink_operations;
2471 #ifdef CONFIG_TMPFS_XATTR
2472 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2474 #define shmem_initxattrs NULL
2478 shmem_write_begin(struct file *file, struct address_space *mapping,
2479 loff_t pos, unsigned len,
2480 struct page **pagep, void **fsdata)
2482 struct inode *inode = mapping->host;
2483 struct shmem_inode_info *info = SHMEM_I(inode);
2484 pgoff_t index = pos >> PAGE_SHIFT;
2487 /* i_rwsem is held by caller */
2488 if (unlikely(info->seals & (F_SEAL_GROW |
2489 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2490 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2492 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2496 ret = shmem_getpage(inode, index, pagep, SGP_WRITE);
2501 if (PageHWPoison(*pagep)) {
2502 unlock_page(*pagep);
2512 shmem_write_end(struct file *file, struct address_space *mapping,
2513 loff_t pos, unsigned len, unsigned copied,
2514 struct page *page, void *fsdata)
2516 struct inode *inode = mapping->host;
2518 if (pos + copied > inode->i_size)
2519 i_size_write(inode, pos + copied);
2521 if (!PageUptodate(page)) {
2522 struct page *head = compound_head(page);
2523 if (PageTransCompound(page)) {
2526 for (i = 0; i < HPAGE_PMD_NR; i++) {
2527 if (head + i == page)
2529 clear_highpage(head + i);
2530 flush_dcache_page(head + i);
2533 if (copied < PAGE_SIZE) {
2534 unsigned from = pos & (PAGE_SIZE - 1);
2535 zero_user_segments(page, 0, from,
2536 from + copied, PAGE_SIZE);
2538 SetPageUptodate(head);
2540 set_page_dirty(page);
2547 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2549 struct file *file = iocb->ki_filp;
2550 struct inode *inode = file_inode(file);
2551 struct address_space *mapping = inode->i_mapping;
2553 unsigned long offset;
2556 loff_t *ppos = &iocb->ki_pos;
2558 index = *ppos >> PAGE_SHIFT;
2559 offset = *ppos & ~PAGE_MASK;
2562 struct page *page = NULL;
2564 unsigned long nr, ret;
2565 loff_t i_size = i_size_read(inode);
2567 end_index = i_size >> PAGE_SHIFT;
2568 if (index > end_index)
2570 if (index == end_index) {
2571 nr = i_size & ~PAGE_MASK;
2576 error = shmem_getpage(inode, index, &page, SGP_READ);
2578 if (error == -EINVAL)
2585 if (PageHWPoison(page)) {
2593 * We must evaluate after, since reads (unlike writes)
2594 * are called without i_rwsem protection against truncate
2597 i_size = i_size_read(inode);
2598 end_index = i_size >> PAGE_SHIFT;
2599 if (index == end_index) {
2600 nr = i_size & ~PAGE_MASK;
2611 * If users can be writing to this page using arbitrary
2612 * virtual addresses, take care about potential aliasing
2613 * before reading the page on the kernel side.
2615 if (mapping_writably_mapped(mapping))
2616 flush_dcache_page(page);
2618 * Mark the page accessed if we read the beginning.
2621 mark_page_accessed(page);
2623 * Ok, we have the page, and it's up-to-date, so
2624 * now we can copy it to user space...
2626 ret = copy_page_to_iter(page, offset, nr, to);
2629 } else if (user_backed_iter(to)) {
2631 * Copy to user tends to be so well optimized, but
2632 * clear_user() not so much, that it is noticeably
2633 * faster to copy the zero page instead of clearing.
2635 ret = copy_page_to_iter(ZERO_PAGE(0), offset, nr, to);
2638 * But submitting the same page twice in a row to
2639 * splice() - or others? - can result in confusion:
2640 * so don't attempt that optimization on pipes etc.
2642 ret = iov_iter_zero(nr, to);
2647 index += offset >> PAGE_SHIFT;
2648 offset &= ~PAGE_MASK;
2650 if (!iov_iter_count(to))
2659 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2660 file_accessed(file);
2661 return retval ? retval : error;
2664 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2666 struct address_space *mapping = file->f_mapping;
2667 struct inode *inode = mapping->host;
2669 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2670 return generic_file_llseek_size(file, offset, whence,
2671 MAX_LFS_FILESIZE, i_size_read(inode));
2676 /* We're holding i_rwsem so we can access i_size directly */
2677 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
2679 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2680 inode_unlock(inode);
2684 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2687 struct inode *inode = file_inode(file);
2688 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2689 struct shmem_inode_info *info = SHMEM_I(inode);
2690 struct shmem_falloc shmem_falloc;
2691 pgoff_t start, index, end, undo_fallocend;
2694 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2699 if (mode & FALLOC_FL_PUNCH_HOLE) {
2700 struct address_space *mapping = file->f_mapping;
2701 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2702 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2703 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2705 /* protected by i_rwsem */
2706 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
2711 shmem_falloc.waitq = &shmem_falloc_waitq;
2712 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
2713 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2714 spin_lock(&inode->i_lock);
2715 inode->i_private = &shmem_falloc;
2716 spin_unlock(&inode->i_lock);
2718 if ((u64)unmap_end > (u64)unmap_start)
2719 unmap_mapping_range(mapping, unmap_start,
2720 1 + unmap_end - unmap_start, 0);
2721 shmem_truncate_range(inode, offset, offset + len - 1);
2722 /* No need to unmap again: hole-punching leaves COWed pages */
2724 spin_lock(&inode->i_lock);
2725 inode->i_private = NULL;
2726 wake_up_all(&shmem_falloc_waitq);
2727 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2728 spin_unlock(&inode->i_lock);
2733 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2734 error = inode_newsize_ok(inode, offset + len);
2738 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2743 start = offset >> PAGE_SHIFT;
2744 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2745 /* Try to avoid a swapstorm if len is impossible to satisfy */
2746 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2751 shmem_falloc.waitq = NULL;
2752 shmem_falloc.start = start;
2753 shmem_falloc.next = start;
2754 shmem_falloc.nr_falloced = 0;
2755 shmem_falloc.nr_unswapped = 0;
2756 spin_lock(&inode->i_lock);
2757 inode->i_private = &shmem_falloc;
2758 spin_unlock(&inode->i_lock);
2761 * info->fallocend is only relevant when huge pages might be
2762 * involved: to prevent split_huge_page() freeing fallocated
2763 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
2765 undo_fallocend = info->fallocend;
2766 if (info->fallocend < end)
2767 info->fallocend = end;
2769 for (index = start; index < end; ) {
2773 * Good, the fallocate(2) manpage permits EINTR: we may have
2774 * been interrupted because we are using up too much memory.
2776 if (signal_pending(current))
2778 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2781 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2783 info->fallocend = undo_fallocend;
2784 /* Remove the !PageUptodate pages we added */
2785 if (index > start) {
2786 shmem_undo_range(inode,
2787 (loff_t)start << PAGE_SHIFT,
2788 ((loff_t)index << PAGE_SHIFT) - 1, true);
2795 * Here is a more important optimization than it appears:
2796 * a second SGP_FALLOC on the same huge page will clear it,
2797 * making it PageUptodate and un-undoable if we fail later.
2799 if (PageTransCompound(page)) {
2800 index = round_up(index, HPAGE_PMD_NR);
2801 /* Beware 32-bit wraparound */
2807 * Inform shmem_writepage() how far we have reached.
2808 * No need for lock or barrier: we have the page lock.
2810 if (!PageUptodate(page))
2811 shmem_falloc.nr_falloced += index - shmem_falloc.next;
2812 shmem_falloc.next = index;
2815 * If !PageUptodate, leave it that way so that freeable pages
2816 * can be recognized if we need to rollback on error later.
2817 * But set_page_dirty so that memory pressure will swap rather
2818 * than free the pages we are allocating (and SGP_CACHE pages
2819 * might still be clean: we now need to mark those dirty too).
2821 set_page_dirty(page);
2827 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2828 i_size_write(inode, offset + len);
2829 inode->i_ctime = current_time(inode);
2831 spin_lock(&inode->i_lock);
2832 inode->i_private = NULL;
2833 spin_unlock(&inode->i_lock);
2835 inode_unlock(inode);
2839 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2841 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2843 buf->f_type = TMPFS_MAGIC;
2844 buf->f_bsize = PAGE_SIZE;
2845 buf->f_namelen = NAME_MAX;
2846 if (sbinfo->max_blocks) {
2847 buf->f_blocks = sbinfo->max_blocks;
2849 buf->f_bfree = sbinfo->max_blocks -
2850 percpu_counter_sum(&sbinfo->used_blocks);
2852 if (sbinfo->max_inodes) {
2853 buf->f_files = sbinfo->max_inodes;
2854 buf->f_ffree = sbinfo->free_inodes;
2856 /* else leave those fields 0 like simple_statfs */
2858 buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
2864 * File creation. Allocate an inode, and we're done..
2867 shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
2868 struct dentry *dentry, umode_t mode, dev_t dev)
2870 struct inode *inode;
2871 int error = -ENOSPC;
2873 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2875 error = simple_acl_create(dir, inode);
2878 error = security_inode_init_security(inode, dir,
2880 shmem_initxattrs, NULL);
2881 if (error && error != -EOPNOTSUPP)
2885 dir->i_size += BOGO_DIRENT_SIZE;
2886 dir->i_ctime = dir->i_mtime = current_time(dir);
2887 d_instantiate(dentry, inode);
2888 dget(dentry); /* Extra count - pin the dentry in core */
2897 shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
2898 struct dentry *dentry, umode_t mode)
2900 struct inode *inode;
2901 int error = -ENOSPC;
2903 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2905 error = security_inode_init_security(inode, dir,
2907 shmem_initxattrs, NULL);
2908 if (error && error != -EOPNOTSUPP)
2910 error = simple_acl_create(dir, inode);
2913 d_tmpfile(dentry, inode);
2921 static int shmem_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
2922 struct dentry *dentry, umode_t mode)
2926 if ((error = shmem_mknod(&init_user_ns, dir, dentry,
2927 mode | S_IFDIR, 0)))
2933 static int shmem_create(struct user_namespace *mnt_userns, struct inode *dir,
2934 struct dentry *dentry, umode_t mode, bool excl)
2936 return shmem_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0);
2942 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2944 struct inode *inode = d_inode(old_dentry);
2948 * No ordinary (disk based) filesystem counts links as inodes;
2949 * but each new link needs a new dentry, pinning lowmem, and
2950 * tmpfs dentries cannot be pruned until they are unlinked.
2951 * But if an O_TMPFILE file is linked into the tmpfs, the
2952 * first link must skip that, to get the accounting right.
2954 if (inode->i_nlink) {
2955 ret = shmem_reserve_inode(inode->i_sb, NULL);
2960 dir->i_size += BOGO_DIRENT_SIZE;
2961 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2963 ihold(inode); /* New dentry reference */
2964 dget(dentry); /* Extra pinning count for the created dentry */
2965 d_instantiate(dentry, inode);
2970 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2972 struct inode *inode = d_inode(dentry);
2974 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2975 shmem_free_inode(inode->i_sb);
2977 dir->i_size -= BOGO_DIRENT_SIZE;
2978 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2980 dput(dentry); /* Undo the count from "create" - this does all the work */
2984 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2986 if (!simple_empty(dentry))
2989 drop_nlink(d_inode(dentry));
2991 return shmem_unlink(dir, dentry);
2994 static int shmem_whiteout(struct user_namespace *mnt_userns,
2995 struct inode *old_dir, struct dentry *old_dentry)
2997 struct dentry *whiteout;
3000 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3004 error = shmem_mknod(&init_user_ns, old_dir, whiteout,
3005 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3011 * Cheat and hash the whiteout while the old dentry is still in
3012 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3014 * d_lookup() will consistently find one of them at this point,
3015 * not sure which one, but that isn't even important.
3022 * The VFS layer already does all the dentry stuff for rename,
3023 * we just have to decrement the usage count for the target if
3024 * it exists so that the VFS layer correctly free's it when it
3027 static int shmem_rename2(struct user_namespace *mnt_userns,
3028 struct inode *old_dir, struct dentry *old_dentry,
3029 struct inode *new_dir, struct dentry *new_dentry,
3032 struct inode *inode = d_inode(old_dentry);
3033 int they_are_dirs = S_ISDIR(inode->i_mode);
3035 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3038 if (flags & RENAME_EXCHANGE)
3039 return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry);
3041 if (!simple_empty(new_dentry))
3044 if (flags & RENAME_WHITEOUT) {
3047 error = shmem_whiteout(&init_user_ns, old_dir, old_dentry);
3052 if (d_really_is_positive(new_dentry)) {
3053 (void) shmem_unlink(new_dir, new_dentry);
3054 if (they_are_dirs) {
3055 drop_nlink(d_inode(new_dentry));
3056 drop_nlink(old_dir);
3058 } else if (they_are_dirs) {
3059 drop_nlink(old_dir);
3063 old_dir->i_size -= BOGO_DIRENT_SIZE;
3064 new_dir->i_size += BOGO_DIRENT_SIZE;
3065 old_dir->i_ctime = old_dir->i_mtime =
3066 new_dir->i_ctime = new_dir->i_mtime =
3067 inode->i_ctime = current_time(old_dir);
3071 static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir,
3072 struct dentry *dentry, const char *symname)
3076 struct inode *inode;
3079 len = strlen(symname) + 1;
3080 if (len > PAGE_SIZE)
3081 return -ENAMETOOLONG;
3083 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0,
3088 error = security_inode_init_security(inode, dir, &dentry->d_name,
3089 shmem_initxattrs, NULL);
3090 if (error && error != -EOPNOTSUPP) {
3095 inode->i_size = len-1;
3096 if (len <= SHORT_SYMLINK_LEN) {
3097 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3098 if (!inode->i_link) {
3102 inode->i_op = &shmem_short_symlink_operations;
3104 inode_nohighmem(inode);
3105 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3110 inode->i_mapping->a_ops = &shmem_aops;
3111 inode->i_op = &shmem_symlink_inode_operations;
3112 memcpy(page_address(page), symname, len);
3113 SetPageUptodate(page);
3114 set_page_dirty(page);
3118 dir->i_size += BOGO_DIRENT_SIZE;
3119 dir->i_ctime = dir->i_mtime = current_time(dir);
3120 d_instantiate(dentry, inode);
3125 static void shmem_put_link(void *arg)
3127 mark_page_accessed(arg);
3131 static const char *shmem_get_link(struct dentry *dentry,
3132 struct inode *inode,
3133 struct delayed_call *done)
3135 struct page *page = NULL;
3138 page = find_get_page(inode->i_mapping, 0);
3140 return ERR_PTR(-ECHILD);
3141 if (PageHWPoison(page) ||
3142 !PageUptodate(page)) {
3144 return ERR_PTR(-ECHILD);
3147 error = shmem_getpage(inode, 0, &page, SGP_READ);
3149 return ERR_PTR(error);
3151 return ERR_PTR(-ECHILD);
3152 if (PageHWPoison(page)) {
3155 return ERR_PTR(-ECHILD);
3159 set_delayed_call(done, shmem_put_link, page);
3160 return page_address(page);
3163 #ifdef CONFIG_TMPFS_XATTR
3165 static int shmem_fileattr_get(struct dentry *dentry, struct fileattr *fa)
3167 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3169 fileattr_fill_flags(fa, info->fsflags & SHMEM_FL_USER_VISIBLE);
3174 static int shmem_fileattr_set(struct user_namespace *mnt_userns,
3175 struct dentry *dentry, struct fileattr *fa)
3177 struct inode *inode = d_inode(dentry);
3178 struct shmem_inode_info *info = SHMEM_I(inode);
3180 if (fileattr_has_fsx(fa))
3183 info->fsflags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
3184 (fa->flags & SHMEM_FL_USER_MODIFIABLE);
3186 inode->i_flags &= ~(S_APPEND | S_IMMUTABLE | S_NOATIME);
3187 if (info->fsflags & FS_APPEND_FL)
3188 inode->i_flags |= S_APPEND;
3189 if (info->fsflags & FS_IMMUTABLE_FL)
3190 inode->i_flags |= S_IMMUTABLE;
3191 if (info->fsflags & FS_NOATIME_FL)
3192 inode->i_flags |= S_NOATIME;
3194 inode->i_ctime = current_time(inode);
3199 * Superblocks without xattr inode operations may get some security.* xattr
3200 * support from the LSM "for free". As soon as we have any other xattrs
3201 * like ACLs, we also need to implement the security.* handlers at
3202 * filesystem level, though.
3206 * Callback for security_inode_init_security() for acquiring xattrs.
3208 static int shmem_initxattrs(struct inode *inode,
3209 const struct xattr *xattr_array,
3212 struct shmem_inode_info *info = SHMEM_I(inode);
3213 const struct xattr *xattr;
3214 struct simple_xattr *new_xattr;
3217 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3218 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3222 len = strlen(xattr->name) + 1;
3223 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3225 if (!new_xattr->name) {
3230 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3231 XATTR_SECURITY_PREFIX_LEN);
3232 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3235 simple_xattr_list_add(&info->xattrs, new_xattr);
3241 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3242 struct dentry *unused, struct inode *inode,
3243 const char *name, void *buffer, size_t size)
3245 struct shmem_inode_info *info = SHMEM_I(inode);
3247 name = xattr_full_name(handler, name);
3248 return simple_xattr_get(&info->xattrs, name, buffer, size);
3251 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3252 struct user_namespace *mnt_userns,
3253 struct dentry *unused, struct inode *inode,
3254 const char *name, const void *value,
3255 size_t size, int flags)
3257 struct shmem_inode_info *info = SHMEM_I(inode);
3259 name = xattr_full_name(handler, name);
3260 return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
3263 static const struct xattr_handler shmem_security_xattr_handler = {
3264 .prefix = XATTR_SECURITY_PREFIX,
3265 .get = shmem_xattr_handler_get,
3266 .set = shmem_xattr_handler_set,
3269 static const struct xattr_handler shmem_trusted_xattr_handler = {
3270 .prefix = XATTR_TRUSTED_PREFIX,
3271 .get = shmem_xattr_handler_get,
3272 .set = shmem_xattr_handler_set,
3275 static const struct xattr_handler *shmem_xattr_handlers[] = {
3276 #ifdef CONFIG_TMPFS_POSIX_ACL
3277 &posix_acl_access_xattr_handler,
3278 &posix_acl_default_xattr_handler,
3280 &shmem_security_xattr_handler,
3281 &shmem_trusted_xattr_handler,
3285 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3287 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3288 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3290 #endif /* CONFIG_TMPFS_XATTR */
3292 static const struct inode_operations shmem_short_symlink_operations = {
3293 .getattr = shmem_getattr,
3294 .get_link = simple_get_link,
3295 #ifdef CONFIG_TMPFS_XATTR
3296 .listxattr = shmem_listxattr,
3300 static const struct inode_operations shmem_symlink_inode_operations = {
3301 .getattr = shmem_getattr,
3302 .get_link = shmem_get_link,
3303 #ifdef CONFIG_TMPFS_XATTR
3304 .listxattr = shmem_listxattr,
3308 static struct dentry *shmem_get_parent(struct dentry *child)
3310 return ERR_PTR(-ESTALE);
3313 static int shmem_match(struct inode *ino, void *vfh)
3317 inum = (inum << 32) | fh[1];
3318 return ino->i_ino == inum && fh[0] == ino->i_generation;
3321 /* Find any alias of inode, but prefer a hashed alias */
3322 static struct dentry *shmem_find_alias(struct inode *inode)
3324 struct dentry *alias = d_find_alias(inode);
3326 return alias ?: d_find_any_alias(inode);
3330 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3331 struct fid *fid, int fh_len, int fh_type)
3333 struct inode *inode;
3334 struct dentry *dentry = NULL;
3341 inum = (inum << 32) | fid->raw[1];
3343 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3344 shmem_match, fid->raw);
3346 dentry = shmem_find_alias(inode);
3353 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3354 struct inode *parent)
3358 return FILEID_INVALID;
3361 if (inode_unhashed(inode)) {
3362 /* Unfortunately insert_inode_hash is not idempotent,
3363 * so as we hash inodes here rather than at creation
3364 * time, we need a lock to ensure we only try
3367 static DEFINE_SPINLOCK(lock);
3369 if (inode_unhashed(inode))
3370 __insert_inode_hash(inode,
3371 inode->i_ino + inode->i_generation);
3375 fh[0] = inode->i_generation;
3376 fh[1] = inode->i_ino;
3377 fh[2] = ((__u64)inode->i_ino) >> 32;
3383 static const struct export_operations shmem_export_ops = {
3384 .get_parent = shmem_get_parent,
3385 .encode_fh = shmem_encode_fh,
3386 .fh_to_dentry = shmem_fh_to_dentry,
3402 static const struct constant_table shmem_param_enums_huge[] = {
3403 {"never", SHMEM_HUGE_NEVER },
3404 {"always", SHMEM_HUGE_ALWAYS },
3405 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3406 {"advise", SHMEM_HUGE_ADVISE },
3410 const struct fs_parameter_spec shmem_fs_parameters[] = {
3411 fsparam_u32 ("gid", Opt_gid),
3412 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3413 fsparam_u32oct("mode", Opt_mode),
3414 fsparam_string("mpol", Opt_mpol),
3415 fsparam_string("nr_blocks", Opt_nr_blocks),
3416 fsparam_string("nr_inodes", Opt_nr_inodes),
3417 fsparam_string("size", Opt_size),
3418 fsparam_u32 ("uid", Opt_uid),
3419 fsparam_flag ("inode32", Opt_inode32),
3420 fsparam_flag ("inode64", Opt_inode64),
3424 static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3426 struct shmem_options *ctx = fc->fs_private;
3427 struct fs_parse_result result;
3428 unsigned long long size;
3432 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3438 size = memparse(param->string, &rest);
3440 size <<= PAGE_SHIFT;
3441 size *= totalram_pages();
3447 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3448 ctx->seen |= SHMEM_SEEN_BLOCKS;
3451 ctx->blocks = memparse(param->string, &rest);
3452 if (*rest || ctx->blocks > S64_MAX)
3454 ctx->seen |= SHMEM_SEEN_BLOCKS;
3457 ctx->inodes = memparse(param->string, &rest);
3460 ctx->seen |= SHMEM_SEEN_INODES;
3463 ctx->mode = result.uint_32 & 07777;
3466 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
3467 if (!uid_valid(ctx->uid))
3471 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
3472 if (!gid_valid(ctx->gid))
3476 ctx->huge = result.uint_32;
3477 if (ctx->huge != SHMEM_HUGE_NEVER &&
3478 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
3479 has_transparent_hugepage()))
3480 goto unsupported_parameter;
3481 ctx->seen |= SHMEM_SEEN_HUGE;
3484 if (IS_ENABLED(CONFIG_NUMA)) {
3485 mpol_put(ctx->mpol);
3487 if (mpol_parse_str(param->string, &ctx->mpol))
3491 goto unsupported_parameter;
3493 ctx->full_inums = false;
3494 ctx->seen |= SHMEM_SEEN_INUMS;
3497 if (sizeof(ino_t) < 8) {
3499 "Cannot use inode64 with <64bit inums in kernel\n");
3501 ctx->full_inums = true;
3502 ctx->seen |= SHMEM_SEEN_INUMS;
3507 unsupported_parameter:
3508 return invalfc(fc, "Unsupported parameter '%s'", param->key);
3510 return invalfc(fc, "Bad value for '%s'", param->key);
3513 static int shmem_parse_options(struct fs_context *fc, void *data)
3515 char *options = data;
3518 int err = security_sb_eat_lsm_opts(options, &fc->security);
3523 while (options != NULL) {
3524 char *this_char = options;
3527 * NUL-terminate this option: unfortunately,
3528 * mount options form a comma-separated list,
3529 * but mpol's nodelist may also contain commas.
3531 options = strchr(options, ',');
3532 if (options == NULL)
3535 if (!isdigit(*options)) {
3541 char *value = strchr(this_char, '=');
3547 len = strlen(value);
3549 err = vfs_parse_fs_string(fc, this_char, value, len);
3558 * Reconfigure a shmem filesystem.
3560 * Note that we disallow change from limited->unlimited blocks/inodes while any
3561 * are in use; but we must separately disallow unlimited->limited, because in
3562 * that case we have no record of how much is already in use.
3564 static int shmem_reconfigure(struct fs_context *fc)
3566 struct shmem_options *ctx = fc->fs_private;
3567 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
3568 unsigned long inodes;
3569 struct mempolicy *mpol = NULL;
3572 raw_spin_lock(&sbinfo->stat_lock);
3573 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3575 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
3576 if (!sbinfo->max_blocks) {
3577 err = "Cannot retroactively limit size";
3580 if (percpu_counter_compare(&sbinfo->used_blocks,
3582 err = "Too small a size for current use";
3586 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
3587 if (!sbinfo->max_inodes) {
3588 err = "Cannot retroactively limit inodes";
3591 if (ctx->inodes < inodes) {
3592 err = "Too few inodes for current use";
3597 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
3598 sbinfo->next_ino > UINT_MAX) {
3599 err = "Current inum too high to switch to 32-bit inums";
3603 if (ctx->seen & SHMEM_SEEN_HUGE)
3604 sbinfo->huge = ctx->huge;
3605 if (ctx->seen & SHMEM_SEEN_INUMS)
3606 sbinfo->full_inums = ctx->full_inums;
3607 if (ctx->seen & SHMEM_SEEN_BLOCKS)
3608 sbinfo->max_blocks = ctx->blocks;
3609 if (ctx->seen & SHMEM_SEEN_INODES) {
3610 sbinfo->max_inodes = ctx->inodes;
3611 sbinfo->free_inodes = ctx->inodes - inodes;
3615 * Preserve previous mempolicy unless mpol remount option was specified.
3618 mpol = sbinfo->mpol;
3619 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
3622 raw_spin_unlock(&sbinfo->stat_lock);
3626 raw_spin_unlock(&sbinfo->stat_lock);
3627 return invalfc(fc, "%s", err);
3630 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3632 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3634 if (sbinfo->max_blocks != shmem_default_max_blocks())
3635 seq_printf(seq, ",size=%luk",
3636 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3637 if (sbinfo->max_inodes != shmem_default_max_inodes())
3638 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3639 if (sbinfo->mode != (0777 | S_ISVTX))
3640 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3641 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3642 seq_printf(seq, ",uid=%u",
3643 from_kuid_munged(&init_user_ns, sbinfo->uid));
3644 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3645 seq_printf(seq, ",gid=%u",
3646 from_kgid_munged(&init_user_ns, sbinfo->gid));
3649 * Showing inode{64,32} might be useful even if it's the system default,
3650 * since then people don't have to resort to checking both here and
3651 * /proc/config.gz to confirm 64-bit inums were successfully applied
3652 * (which may not even exist if IKCONFIG_PROC isn't enabled).
3654 * We hide it when inode64 isn't the default and we are using 32-bit
3655 * inodes, since that probably just means the feature isn't even under
3660 * +-----------------+-----------------+
3661 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
3662 * +------------------+-----------------+-----------------+
3663 * | full_inums=true | show | show |
3664 * | full_inums=false | show | hide |
3665 * +------------------+-----------------+-----------------+
3668 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
3669 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
3670 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3671 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3673 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3675 shmem_show_mpol(seq, sbinfo->mpol);
3679 #endif /* CONFIG_TMPFS */
3681 static void shmem_put_super(struct super_block *sb)
3683 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3685 free_percpu(sbinfo->ino_batch);
3686 percpu_counter_destroy(&sbinfo->used_blocks);
3687 mpol_put(sbinfo->mpol);
3689 sb->s_fs_info = NULL;
3692 static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
3694 struct shmem_options *ctx = fc->fs_private;
3695 struct inode *inode;
3696 struct shmem_sb_info *sbinfo;
3698 /* Round up to L1_CACHE_BYTES to resist false sharing */
3699 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3700 L1_CACHE_BYTES), GFP_KERNEL);
3704 sb->s_fs_info = sbinfo;
3708 * Per default we only allow half of the physical ram per
3709 * tmpfs instance, limiting inodes to one per page of lowmem;
3710 * but the internal instance is left unlimited.
3712 if (!(sb->s_flags & SB_KERNMOUNT)) {
3713 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
3714 ctx->blocks = shmem_default_max_blocks();
3715 if (!(ctx->seen & SHMEM_SEEN_INODES))
3716 ctx->inodes = shmem_default_max_inodes();
3717 if (!(ctx->seen & SHMEM_SEEN_INUMS))
3718 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
3720 sb->s_flags |= SB_NOUSER;
3722 sb->s_export_op = &shmem_export_ops;
3723 sb->s_flags |= SB_NOSEC;
3725 sb->s_flags |= SB_NOUSER;
3727 sbinfo->max_blocks = ctx->blocks;
3728 sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
3729 if (sb->s_flags & SB_KERNMOUNT) {
3730 sbinfo->ino_batch = alloc_percpu(ino_t);
3731 if (!sbinfo->ino_batch)
3734 sbinfo->uid = ctx->uid;
3735 sbinfo->gid = ctx->gid;
3736 sbinfo->full_inums = ctx->full_inums;
3737 sbinfo->mode = ctx->mode;
3738 sbinfo->huge = ctx->huge;
3739 sbinfo->mpol = ctx->mpol;
3742 raw_spin_lock_init(&sbinfo->stat_lock);
3743 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3745 spin_lock_init(&sbinfo->shrinklist_lock);
3746 INIT_LIST_HEAD(&sbinfo->shrinklist);
3748 sb->s_maxbytes = MAX_LFS_FILESIZE;
3749 sb->s_blocksize = PAGE_SIZE;
3750 sb->s_blocksize_bits = PAGE_SHIFT;
3751 sb->s_magic = TMPFS_MAGIC;
3752 sb->s_op = &shmem_ops;
3753 sb->s_time_gran = 1;
3754 #ifdef CONFIG_TMPFS_XATTR
3755 sb->s_xattr = shmem_xattr_handlers;
3757 #ifdef CONFIG_TMPFS_POSIX_ACL
3758 sb->s_flags |= SB_POSIXACL;
3760 uuid_gen(&sb->s_uuid);
3762 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3765 inode->i_uid = sbinfo->uid;
3766 inode->i_gid = sbinfo->gid;
3767 sb->s_root = d_make_root(inode);
3773 shmem_put_super(sb);
3777 static int shmem_get_tree(struct fs_context *fc)
3779 return get_tree_nodev(fc, shmem_fill_super);
3782 static void shmem_free_fc(struct fs_context *fc)
3784 struct shmem_options *ctx = fc->fs_private;
3787 mpol_put(ctx->mpol);
3792 static const struct fs_context_operations shmem_fs_context_ops = {
3793 .free = shmem_free_fc,
3794 .get_tree = shmem_get_tree,
3796 .parse_monolithic = shmem_parse_options,
3797 .parse_param = shmem_parse_one,
3798 .reconfigure = shmem_reconfigure,
3802 static struct kmem_cache *shmem_inode_cachep;
3804 static struct inode *shmem_alloc_inode(struct super_block *sb)
3806 struct shmem_inode_info *info;
3807 info = alloc_inode_sb(sb, shmem_inode_cachep, GFP_KERNEL);
3810 return &info->vfs_inode;
3813 static void shmem_free_in_core_inode(struct inode *inode)
3815 if (S_ISLNK(inode->i_mode))
3816 kfree(inode->i_link);
3817 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3820 static void shmem_destroy_inode(struct inode *inode)
3822 if (S_ISREG(inode->i_mode))
3823 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3826 static void shmem_init_inode(void *foo)
3828 struct shmem_inode_info *info = foo;
3829 inode_init_once(&info->vfs_inode);
3832 static void shmem_init_inodecache(void)
3834 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3835 sizeof(struct shmem_inode_info),
3836 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3839 static void shmem_destroy_inodecache(void)
3841 kmem_cache_destroy(shmem_inode_cachep);
3844 /* Keep the page in page cache instead of truncating it */
3845 static int shmem_error_remove_page(struct address_space *mapping,
3851 const struct address_space_operations shmem_aops = {
3852 .writepage = shmem_writepage,
3853 .dirty_folio = noop_dirty_folio,
3855 .write_begin = shmem_write_begin,
3856 .write_end = shmem_write_end,
3858 #ifdef CONFIG_MIGRATION
3859 .migrate_folio = migrate_folio,
3861 .error_remove_page = shmem_error_remove_page,
3863 EXPORT_SYMBOL(shmem_aops);
3865 static const struct file_operations shmem_file_operations = {
3867 .get_unmapped_area = shmem_get_unmapped_area,
3869 .llseek = shmem_file_llseek,
3870 .read_iter = shmem_file_read_iter,
3871 .write_iter = generic_file_write_iter,
3872 .fsync = noop_fsync,
3873 .splice_read = generic_file_splice_read,
3874 .splice_write = iter_file_splice_write,
3875 .fallocate = shmem_fallocate,
3879 static const struct inode_operations shmem_inode_operations = {
3880 .getattr = shmem_getattr,
3881 .setattr = shmem_setattr,
3882 #ifdef CONFIG_TMPFS_XATTR
3883 .listxattr = shmem_listxattr,
3884 .set_acl = simple_set_acl,
3885 .fileattr_get = shmem_fileattr_get,
3886 .fileattr_set = shmem_fileattr_set,
3890 static const struct inode_operations shmem_dir_inode_operations = {
3892 .getattr = shmem_getattr,
3893 .create = shmem_create,
3894 .lookup = simple_lookup,
3896 .unlink = shmem_unlink,
3897 .symlink = shmem_symlink,
3898 .mkdir = shmem_mkdir,
3899 .rmdir = shmem_rmdir,
3900 .mknod = shmem_mknod,
3901 .rename = shmem_rename2,
3902 .tmpfile = shmem_tmpfile,
3904 #ifdef CONFIG_TMPFS_XATTR
3905 .listxattr = shmem_listxattr,
3906 .fileattr_get = shmem_fileattr_get,
3907 .fileattr_set = shmem_fileattr_set,
3909 #ifdef CONFIG_TMPFS_POSIX_ACL
3910 .setattr = shmem_setattr,
3911 .set_acl = simple_set_acl,
3915 static const struct inode_operations shmem_special_inode_operations = {
3916 .getattr = shmem_getattr,
3917 #ifdef CONFIG_TMPFS_XATTR
3918 .listxattr = shmem_listxattr,
3920 #ifdef CONFIG_TMPFS_POSIX_ACL
3921 .setattr = shmem_setattr,
3922 .set_acl = simple_set_acl,
3926 static const struct super_operations shmem_ops = {
3927 .alloc_inode = shmem_alloc_inode,
3928 .free_inode = shmem_free_in_core_inode,
3929 .destroy_inode = shmem_destroy_inode,
3931 .statfs = shmem_statfs,
3932 .show_options = shmem_show_options,
3934 .evict_inode = shmem_evict_inode,
3935 .drop_inode = generic_delete_inode,
3936 .put_super = shmem_put_super,
3937 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3938 .nr_cached_objects = shmem_unused_huge_count,
3939 .free_cached_objects = shmem_unused_huge_scan,
3943 static const struct vm_operations_struct shmem_vm_ops = {
3944 .fault = shmem_fault,
3945 .map_pages = filemap_map_pages,
3947 .set_policy = shmem_set_policy,
3948 .get_policy = shmem_get_policy,
3952 int shmem_init_fs_context(struct fs_context *fc)
3954 struct shmem_options *ctx;
3956 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
3960 ctx->mode = 0777 | S_ISVTX;
3961 ctx->uid = current_fsuid();
3962 ctx->gid = current_fsgid();
3964 fc->fs_private = ctx;
3965 fc->ops = &shmem_fs_context_ops;
3969 static struct file_system_type shmem_fs_type = {
3970 .owner = THIS_MODULE,
3972 .init_fs_context = shmem_init_fs_context,
3974 .parameters = shmem_fs_parameters,
3976 .kill_sb = kill_litter_super,
3977 .fs_flags = FS_USERNS_MOUNT,
3980 void __init shmem_init(void)
3984 shmem_init_inodecache();
3986 error = register_filesystem(&shmem_fs_type);
3988 pr_err("Could not register tmpfs\n");
3992 shm_mnt = kern_mount(&shmem_fs_type);
3993 if (IS_ERR(shm_mnt)) {
3994 error = PTR_ERR(shm_mnt);
3995 pr_err("Could not kern_mount tmpfs\n");
3999 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4000 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
4001 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4003 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
4008 unregister_filesystem(&shmem_fs_type);
4010 shmem_destroy_inodecache();
4011 shm_mnt = ERR_PTR(error);
4014 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
4015 static ssize_t shmem_enabled_show(struct kobject *kobj,
4016 struct kobj_attribute *attr, char *buf)
4018 static const int values[] = {
4020 SHMEM_HUGE_WITHIN_SIZE,
4029 for (i = 0; i < ARRAY_SIZE(values); i++) {
4030 len += sysfs_emit_at(buf, len,
4031 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
4033 shmem_format_huge(values[i]));
4036 len += sysfs_emit_at(buf, len, "\n");
4041 static ssize_t shmem_enabled_store(struct kobject *kobj,
4042 struct kobj_attribute *attr, const char *buf, size_t count)
4047 if (count + 1 > sizeof(tmp))
4049 memcpy(tmp, buf, count);
4051 if (count && tmp[count - 1] == '\n')
4052 tmp[count - 1] = '\0';
4054 huge = shmem_parse_huge(tmp);
4055 if (huge == -EINVAL)
4057 if (!has_transparent_hugepage() &&
4058 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4062 if (shmem_huge > SHMEM_HUGE_DENY)
4063 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4067 struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
4068 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4070 #else /* !CONFIG_SHMEM */
4073 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4075 * This is intended for small system where the benefits of the full
4076 * shmem code (swap-backed and resource-limited) are outweighed by
4077 * their complexity. On systems without swap this code should be
4078 * effectively equivalent, but much lighter weight.
4081 static struct file_system_type shmem_fs_type = {
4083 .init_fs_context = ramfs_init_fs_context,
4084 .parameters = ramfs_fs_parameters,
4085 .kill_sb = kill_litter_super,
4086 .fs_flags = FS_USERNS_MOUNT,
4089 void __init shmem_init(void)
4091 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4093 shm_mnt = kern_mount(&shmem_fs_type);
4094 BUG_ON(IS_ERR(shm_mnt));
4097 int shmem_unuse(unsigned int type)
4102 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
4107 void shmem_unlock_mapping(struct address_space *mapping)
4112 unsigned long shmem_get_unmapped_area(struct file *file,
4113 unsigned long addr, unsigned long len,
4114 unsigned long pgoff, unsigned long flags)
4116 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4120 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4122 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4124 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4126 #define shmem_vm_ops generic_file_vm_ops
4127 #define shmem_file_operations ramfs_file_operations
4128 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4129 #define shmem_acct_size(flags, size) 0
4130 #define shmem_unacct_size(flags, size) do {} while (0)
4132 #endif /* CONFIG_SHMEM */
4136 static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4137 unsigned long flags, unsigned int i_flags)
4139 struct inode *inode;
4143 return ERR_CAST(mnt);
4145 if (size < 0 || size > MAX_LFS_FILESIZE)
4146 return ERR_PTR(-EINVAL);
4148 if (shmem_acct_size(flags, size))
4149 return ERR_PTR(-ENOMEM);
4151 inode = shmem_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0,
4153 if (unlikely(!inode)) {
4154 shmem_unacct_size(flags, size);
4155 return ERR_PTR(-ENOSPC);
4157 inode->i_flags |= i_flags;
4158 inode->i_size = size;
4159 clear_nlink(inode); /* It is unlinked */
4160 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4162 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4163 &shmem_file_operations);
4170 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4171 * kernel internal. There will be NO LSM permission checks against the
4172 * underlying inode. So users of this interface must do LSM checks at a
4173 * higher layer. The users are the big_key and shm implementations. LSM
4174 * checks are provided at the key or shm level rather than the inode.
4175 * @name: name for dentry (to be seen in /proc/<pid>/maps
4176 * @size: size to be set for the file
4177 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4179 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4181 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4185 * shmem_file_setup - get an unlinked file living in tmpfs
4186 * @name: name for dentry (to be seen in /proc/<pid>/maps
4187 * @size: size to be set for the file
4188 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4190 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4192 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4194 EXPORT_SYMBOL_GPL(shmem_file_setup);
4197 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4198 * @mnt: the tmpfs mount where the file will be created
4199 * @name: name for dentry (to be seen in /proc/<pid>/maps
4200 * @size: size to be set for the file
4201 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4203 struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4204 loff_t size, unsigned long flags)
4206 return __shmem_file_setup(mnt, name, size, flags, 0);
4208 EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4211 * shmem_zero_setup - setup a shared anonymous mapping
4212 * @vma: the vma to be mmapped is prepared by do_mmap
4214 int shmem_zero_setup(struct vm_area_struct *vma)
4217 loff_t size = vma->vm_end - vma->vm_start;
4220 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4221 * between XFS directory reading and selinux: since this file is only
4222 * accessible to the user through its mapping, use S_PRIVATE flag to
4223 * bypass file security, in the same way as shmem_kernel_file_setup().
4225 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4227 return PTR_ERR(file);
4231 vma->vm_file = file;
4232 vma->vm_ops = &shmem_vm_ops;
4238 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4239 * @mapping: the page's address_space
4240 * @index: the page index
4241 * @gfp: the page allocator flags to use if allocating
4243 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4244 * with any new page allocations done using the specified allocation flags.
4245 * But read_cache_page_gfp() uses the ->read_folio() method: which does not
4246 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4247 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4249 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4250 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4252 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4253 pgoff_t index, gfp_t gfp)
4256 struct inode *inode = mapping->host;
4260 BUG_ON(!shmem_mapping(mapping));
4261 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4262 gfp, NULL, NULL, NULL);
4264 return ERR_PTR(error);
4267 if (PageHWPoison(page)) {
4269 return ERR_PTR(-EIO);
4275 * The tiny !SHMEM case uses ramfs without swap
4277 return read_cache_page_gfp(mapping, index, gfp);
4280 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);