2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
21 * This file is released under the GPL.
25 #include <linux/init.h>
26 #include <linux/vfs.h>
27 #include <linux/mount.h>
28 #include <linux/ramfs.h>
29 #include <linux/pagemap.h>
30 #include <linux/file.h>
32 #include <linux/random.h>
33 #include <linux/sched/signal.h>
34 #include <linux/export.h>
35 #include <linux/swap.h>
36 #include <linux/uio.h>
37 #include <linux/khugepaged.h>
38 #include <linux/hugetlb.h>
39 #include <linux/frontswap.h>
40 #include <linux/fs_parser.h>
41 #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/blkdev.h>
63 #include <linux/pagevec.h>
64 #include <linux/percpu_counter.h>
65 #include <linux/falloc.h>
66 #include <linux/splice.h>
67 #include <linux/security.h>
68 #include <linux/swapops.h>
69 #include <linux/mempolicy.h>
70 #include <linux/namei.h>
71 #include <linux/ctype.h>
72 #include <linux/migrate.h>
73 #include <linux/highmem.h>
74 #include <linux/seq_file.h>
75 #include <linux/magic.h>
76 #include <linux/syscalls.h>
77 #include <linux/fcntl.h>
78 #include <uapi/linux/memfd.h>
79 #include <linux/userfaultfd_k.h>
80 #include <linux/rmap.h>
81 #include <linux/uuid.h>
83 #include <linux/uaccess.h>
87 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
88 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
90 /* Pretend that each entry is of this size in directory's i_size */
91 #define BOGO_DIRENT_SIZE 20
93 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
94 #define SHORT_SYMLINK_LEN 128
97 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
98 * inode->i_private (with i_rwsem making sure that it has only one user at
99 * a time): we would prefer not to enlarge the shmem inode just for that.
101 struct shmem_falloc {
102 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
103 pgoff_t start; /* start of range currently being fallocated */
104 pgoff_t next; /* the next page offset to be fallocated */
105 pgoff_t nr_falloced; /* how many new pages have been fallocated */
106 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
109 struct shmem_options {
110 unsigned long long blocks;
111 unsigned long long inodes;
112 struct mempolicy *mpol;
119 #define SHMEM_SEEN_BLOCKS 1
120 #define SHMEM_SEEN_INODES 2
121 #define SHMEM_SEEN_HUGE 4
122 #define SHMEM_SEEN_INUMS 8
126 static unsigned long shmem_default_max_blocks(void)
128 return totalram_pages() / 2;
131 static unsigned long shmem_default_max_inodes(void)
133 unsigned long nr_pages = totalram_pages();
135 return min(nr_pages - totalhigh_pages(), nr_pages / 2);
139 static int shmem_swapin_page(struct inode *inode, pgoff_t index,
140 struct page **pagep, enum sgp_type sgp,
141 gfp_t gfp, struct vm_area_struct *vma,
142 vm_fault_t *fault_type);
143 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
144 struct page **pagep, enum sgp_type sgp,
145 gfp_t gfp, struct vm_area_struct *vma,
146 struct vm_fault *vmf, vm_fault_t *fault_type);
148 int shmem_getpage(struct inode *inode, pgoff_t index,
149 struct page **pagep, enum sgp_type sgp)
151 return shmem_getpage_gfp(inode, index, pagep, sgp,
152 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
155 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
157 return sb->s_fs_info;
161 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
162 * for shared memory and for shared anonymous (/dev/zero) mappings
163 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
164 * consistent with the pre-accounting of private mappings ...
166 static inline int shmem_acct_size(unsigned long flags, loff_t size)
168 return (flags & VM_NORESERVE) ?
169 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
172 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
174 if (!(flags & VM_NORESERVE))
175 vm_unacct_memory(VM_ACCT(size));
178 static inline int shmem_reacct_size(unsigned long flags,
179 loff_t oldsize, loff_t newsize)
181 if (!(flags & VM_NORESERVE)) {
182 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
183 return security_vm_enough_memory_mm(current->mm,
184 VM_ACCT(newsize) - VM_ACCT(oldsize));
185 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
186 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
192 * ... whereas tmpfs objects are accounted incrementally as
193 * pages are allocated, in order to allow large sparse files.
194 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
195 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
197 static inline int shmem_acct_block(unsigned long flags, long pages)
199 if (!(flags & VM_NORESERVE))
202 return security_vm_enough_memory_mm(current->mm,
203 pages * VM_ACCT(PAGE_SIZE));
206 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
208 if (flags & VM_NORESERVE)
209 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
212 static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
214 struct shmem_inode_info *info = SHMEM_I(inode);
215 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
217 if (shmem_acct_block(info->flags, pages))
220 if (sbinfo->max_blocks) {
221 if (percpu_counter_compare(&sbinfo->used_blocks,
222 sbinfo->max_blocks - pages) > 0)
224 percpu_counter_add(&sbinfo->used_blocks, pages);
230 shmem_unacct_blocks(info->flags, pages);
234 static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
236 struct shmem_inode_info *info = SHMEM_I(inode);
237 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
239 if (sbinfo->max_blocks)
240 percpu_counter_sub(&sbinfo->used_blocks, pages);
241 shmem_unacct_blocks(info->flags, pages);
244 static const struct super_operations shmem_ops;
245 const struct address_space_operations shmem_aops;
246 static const struct file_operations shmem_file_operations;
247 static const struct inode_operations shmem_inode_operations;
248 static const struct inode_operations shmem_dir_inode_operations;
249 static const struct inode_operations shmem_special_inode_operations;
250 static const struct vm_operations_struct shmem_vm_ops;
251 static struct file_system_type shmem_fs_type;
253 bool vma_is_shmem(struct vm_area_struct *vma)
255 return vma->vm_ops == &shmem_vm_ops;
258 static LIST_HEAD(shmem_swaplist);
259 static DEFINE_MUTEX(shmem_swaplist_mutex);
262 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
263 * produces a novel ino for the newly allocated inode.
265 * It may also be called when making a hard link to permit the space needed by
266 * each dentry. However, in that case, no new inode number is needed since that
267 * internally draws from another pool of inode numbers (currently global
268 * get_next_ino()). This case is indicated by passing NULL as inop.
270 #define SHMEM_INO_BATCH 1024
271 static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
273 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
276 if (!(sb->s_flags & SB_KERNMOUNT)) {
277 raw_spin_lock(&sbinfo->stat_lock);
278 if (sbinfo->max_inodes) {
279 if (!sbinfo->free_inodes) {
280 raw_spin_unlock(&sbinfo->stat_lock);
283 sbinfo->free_inodes--;
286 ino = sbinfo->next_ino++;
287 if (unlikely(is_zero_ino(ino)))
288 ino = sbinfo->next_ino++;
289 if (unlikely(!sbinfo->full_inums &&
292 * Emulate get_next_ino uint wraparound for
295 if (IS_ENABLED(CONFIG_64BIT))
296 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
297 __func__, MINOR(sb->s_dev));
298 sbinfo->next_ino = 1;
299 ino = sbinfo->next_ino++;
303 raw_spin_unlock(&sbinfo->stat_lock);
306 * __shmem_file_setup, one of our callers, is lock-free: it
307 * doesn't hold stat_lock in shmem_reserve_inode since
308 * max_inodes is always 0, and is called from potentially
309 * unknown contexts. As such, use a per-cpu batched allocator
310 * which doesn't require the per-sb stat_lock unless we are at
311 * the batch boundary.
313 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
314 * shmem mounts are not exposed to userspace, so we don't need
315 * to worry about things like glibc compatibility.
319 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
321 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
322 raw_spin_lock(&sbinfo->stat_lock);
323 ino = sbinfo->next_ino;
324 sbinfo->next_ino += SHMEM_INO_BATCH;
325 raw_spin_unlock(&sbinfo->stat_lock);
326 if (unlikely(is_zero_ino(ino)))
337 static void shmem_free_inode(struct super_block *sb)
339 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
340 if (sbinfo->max_inodes) {
341 raw_spin_lock(&sbinfo->stat_lock);
342 sbinfo->free_inodes++;
343 raw_spin_unlock(&sbinfo->stat_lock);
348 * shmem_recalc_inode - recalculate the block usage of an inode
349 * @inode: inode to recalc
351 * We have to calculate the free blocks since the mm can drop
352 * undirtied hole pages behind our back.
354 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
355 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
357 * It has to be called with the spinlock held.
359 static void shmem_recalc_inode(struct inode *inode)
361 struct shmem_inode_info *info = SHMEM_I(inode);
364 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
366 info->alloced -= freed;
367 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
368 shmem_inode_unacct_blocks(inode, freed);
372 bool shmem_charge(struct inode *inode, long pages)
374 struct shmem_inode_info *info = SHMEM_I(inode);
377 if (!shmem_inode_acct_block(inode, pages))
380 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
381 inode->i_mapping->nrpages += pages;
383 spin_lock_irqsave(&info->lock, flags);
384 info->alloced += pages;
385 inode->i_blocks += pages * BLOCKS_PER_PAGE;
386 shmem_recalc_inode(inode);
387 spin_unlock_irqrestore(&info->lock, flags);
392 void shmem_uncharge(struct inode *inode, long pages)
394 struct shmem_inode_info *info = SHMEM_I(inode);
397 /* nrpages adjustment done by __delete_from_page_cache() or caller */
399 spin_lock_irqsave(&info->lock, flags);
400 info->alloced -= pages;
401 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
402 shmem_recalc_inode(inode);
403 spin_unlock_irqrestore(&info->lock, flags);
405 shmem_inode_unacct_blocks(inode, pages);
409 * Replace item expected in xarray by a new item, while holding xa_lock.
411 static int shmem_replace_entry(struct address_space *mapping,
412 pgoff_t index, void *expected, void *replacement)
414 XA_STATE(xas, &mapping->i_pages, index);
417 VM_BUG_ON(!expected);
418 VM_BUG_ON(!replacement);
419 item = xas_load(&xas);
420 if (item != expected)
422 xas_store(&xas, replacement);
427 * Sometimes, before we decide whether to proceed or to fail, we must check
428 * that an entry was not already brought back from swap by a racing thread.
430 * Checking page is not enough: by the time a SwapCache page is locked, it
431 * might be reused, and again be SwapCache, using the same swap as before.
433 static bool shmem_confirm_swap(struct address_space *mapping,
434 pgoff_t index, swp_entry_t swap)
436 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
440 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
443 * disables huge pages for the mount;
445 * enables huge pages for the mount;
446 * SHMEM_HUGE_WITHIN_SIZE:
447 * only allocate huge pages if the page will be fully within i_size,
448 * also respect fadvise()/madvise() hints;
450 * only allocate huge pages if requested with fadvise()/madvise();
453 #define SHMEM_HUGE_NEVER 0
454 #define SHMEM_HUGE_ALWAYS 1
455 #define SHMEM_HUGE_WITHIN_SIZE 2
456 #define SHMEM_HUGE_ADVISE 3
460 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
463 * disables huge on shm_mnt and all mounts, for emergency use;
465 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
468 #define SHMEM_HUGE_DENY (-1)
469 #define SHMEM_HUGE_FORCE (-2)
471 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
472 /* ifdef here to avoid bloating shmem.o when not necessary */
474 static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
476 bool shmem_is_huge(struct vm_area_struct *vma,
477 struct inode *inode, pgoff_t index)
481 if (shmem_huge == SHMEM_HUGE_DENY)
483 if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) ||
484 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)))
486 if (shmem_huge == SHMEM_HUGE_FORCE)
489 switch (SHMEM_SB(inode->i_sb)->huge) {
490 case SHMEM_HUGE_ALWAYS:
492 case SHMEM_HUGE_WITHIN_SIZE:
493 index = round_up(index + 1, HPAGE_PMD_NR);
494 i_size = round_up(i_size_read(inode), PAGE_SIZE);
495 if (i_size >> PAGE_SHIFT >= index)
498 case SHMEM_HUGE_ADVISE:
499 if (vma && (vma->vm_flags & VM_HUGEPAGE))
507 #if defined(CONFIG_SYSFS)
508 static int shmem_parse_huge(const char *str)
510 if (!strcmp(str, "never"))
511 return SHMEM_HUGE_NEVER;
512 if (!strcmp(str, "always"))
513 return SHMEM_HUGE_ALWAYS;
514 if (!strcmp(str, "within_size"))
515 return SHMEM_HUGE_WITHIN_SIZE;
516 if (!strcmp(str, "advise"))
517 return SHMEM_HUGE_ADVISE;
518 if (!strcmp(str, "deny"))
519 return SHMEM_HUGE_DENY;
520 if (!strcmp(str, "force"))
521 return SHMEM_HUGE_FORCE;
526 #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
527 static const char *shmem_format_huge(int huge)
530 case SHMEM_HUGE_NEVER:
532 case SHMEM_HUGE_ALWAYS:
534 case SHMEM_HUGE_WITHIN_SIZE:
535 return "within_size";
536 case SHMEM_HUGE_ADVISE:
538 case SHMEM_HUGE_DENY:
540 case SHMEM_HUGE_FORCE:
549 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
550 struct shrink_control *sc, unsigned long nr_to_split)
552 LIST_HEAD(list), *pos, *next;
553 LIST_HEAD(to_remove);
555 struct shmem_inode_info *info;
557 unsigned long batch = sc ? sc->nr_to_scan : 128;
560 if (list_empty(&sbinfo->shrinklist))
563 spin_lock(&sbinfo->shrinklist_lock);
564 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
565 info = list_entry(pos, struct shmem_inode_info, shrinklist);
568 inode = igrab(&info->vfs_inode);
570 /* inode is about to be evicted */
572 list_del_init(&info->shrinklist);
576 /* Check if there's anything to gain */
577 if (round_up(inode->i_size, PAGE_SIZE) ==
578 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
579 list_move(&info->shrinklist, &to_remove);
583 list_move(&info->shrinklist, &list);
585 sbinfo->shrinklist_len--;
589 spin_unlock(&sbinfo->shrinklist_lock);
591 list_for_each_safe(pos, next, &to_remove) {
592 info = list_entry(pos, struct shmem_inode_info, shrinklist);
593 inode = &info->vfs_inode;
594 list_del_init(&info->shrinklist);
598 list_for_each_safe(pos, next, &list) {
601 info = list_entry(pos, struct shmem_inode_info, shrinklist);
602 inode = &info->vfs_inode;
604 if (nr_to_split && split >= nr_to_split)
607 page = find_get_page(inode->i_mapping,
608 (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
612 /* No huge page at the end of the file: nothing to split */
613 if (!PageTransHuge(page)) {
619 * Move the inode on the list back to shrinklist if we failed
620 * to lock the page at this time.
622 * Waiting for the lock may lead to deadlock in the
625 if (!trylock_page(page)) {
630 ret = split_huge_page(page);
634 /* If split failed move the inode on the list back to shrinklist */
640 list_del_init(&info->shrinklist);
644 * Make sure the inode is either on the global list or deleted
645 * from any local list before iput() since it could be deleted
646 * in another thread once we put the inode (then the local list
649 spin_lock(&sbinfo->shrinklist_lock);
650 list_move(&info->shrinklist, &sbinfo->shrinklist);
651 sbinfo->shrinklist_len++;
652 spin_unlock(&sbinfo->shrinklist_lock);
660 static long shmem_unused_huge_scan(struct super_block *sb,
661 struct shrink_control *sc)
663 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
665 if (!READ_ONCE(sbinfo->shrinklist_len))
668 return shmem_unused_huge_shrink(sbinfo, sc, 0);
671 static long shmem_unused_huge_count(struct super_block *sb,
672 struct shrink_control *sc)
674 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
675 return READ_ONCE(sbinfo->shrinklist_len);
677 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
679 #define shmem_huge SHMEM_HUGE_DENY
681 bool shmem_is_huge(struct vm_area_struct *vma,
682 struct inode *inode, pgoff_t index)
687 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
688 struct shrink_control *sc, unsigned long nr_to_split)
692 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
695 * Like add_to_page_cache_locked, but error if expected item has gone.
697 static int shmem_add_to_page_cache(struct page *page,
698 struct address_space *mapping,
699 pgoff_t index, void *expected, gfp_t gfp,
700 struct mm_struct *charge_mm)
702 XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
704 unsigned long nr = compound_nr(page);
707 VM_BUG_ON_PAGE(PageTail(page), page);
708 VM_BUG_ON_PAGE(index != round_down(index, nr), page);
709 VM_BUG_ON_PAGE(!PageLocked(page), page);
710 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
711 VM_BUG_ON(expected && PageTransHuge(page));
713 page_ref_add(page, nr);
714 page->mapping = mapping;
717 if (!PageSwapCache(page)) {
718 error = mem_cgroup_charge(page, charge_mm, gfp);
720 if (PageTransHuge(page)) {
721 count_vm_event(THP_FILE_FALLBACK);
722 count_vm_event(THP_FILE_FALLBACK_CHARGE);
727 cgroup_throttle_swaprate(page, gfp);
732 entry = xas_find_conflict(&xas);
733 if (entry != expected)
734 xas_set_err(&xas, -EEXIST);
735 xas_create_range(&xas);
739 xas_store(&xas, page);
744 if (PageTransHuge(page)) {
745 count_vm_event(THP_FILE_ALLOC);
746 __mod_lruvec_page_state(page, NR_SHMEM_THPS, nr);
748 mapping->nrpages += nr;
749 __mod_lruvec_page_state(page, NR_FILE_PAGES, nr);
750 __mod_lruvec_page_state(page, NR_SHMEM, nr);
752 xas_unlock_irq(&xas);
753 } while (xas_nomem(&xas, gfp));
755 if (xas_error(&xas)) {
756 error = xas_error(&xas);
762 page->mapping = NULL;
763 page_ref_sub(page, nr);
768 * Like delete_from_page_cache, but substitutes swap for page.
770 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
772 struct address_space *mapping = page->mapping;
775 VM_BUG_ON_PAGE(PageCompound(page), page);
777 xa_lock_irq(&mapping->i_pages);
778 error = shmem_replace_entry(mapping, page->index, page, radswap);
779 page->mapping = NULL;
781 __dec_lruvec_page_state(page, NR_FILE_PAGES);
782 __dec_lruvec_page_state(page, NR_SHMEM);
783 xa_unlock_irq(&mapping->i_pages);
789 * Remove swap entry from page cache, free the swap and its page cache.
791 static int shmem_free_swap(struct address_space *mapping,
792 pgoff_t index, void *radswap)
796 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
799 free_swap_and_cache(radix_to_swp_entry(radswap));
804 * Determine (in bytes) how many of the shmem object's pages mapped by the
805 * given offsets are swapped out.
807 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
808 * as long as the inode doesn't go away and racy results are not a problem.
810 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
811 pgoff_t start, pgoff_t end)
813 XA_STATE(xas, &mapping->i_pages, start);
815 unsigned long swapped = 0;
818 xas_for_each(&xas, page, end - 1) {
819 if (xas_retry(&xas, page))
821 if (xa_is_value(page))
824 if (need_resched()) {
832 return swapped << PAGE_SHIFT;
836 * Determine (in bytes) how many of the shmem object's pages mapped by the
837 * given vma is swapped out.
839 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
840 * as long as the inode doesn't go away and racy results are not a problem.
842 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
844 struct inode *inode = file_inode(vma->vm_file);
845 struct shmem_inode_info *info = SHMEM_I(inode);
846 struct address_space *mapping = inode->i_mapping;
847 unsigned long swapped;
849 /* Be careful as we don't hold info->lock */
850 swapped = READ_ONCE(info->swapped);
853 * The easier cases are when the shmem object has nothing in swap, or
854 * the vma maps it whole. Then we can simply use the stats that we
860 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
861 return swapped << PAGE_SHIFT;
863 /* Here comes the more involved part */
864 return shmem_partial_swap_usage(mapping,
865 linear_page_index(vma, vma->vm_start),
866 linear_page_index(vma, vma->vm_end));
870 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
872 void shmem_unlock_mapping(struct address_space *mapping)
879 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
881 while (!mapping_unevictable(mapping)) {
882 if (!pagevec_lookup(&pvec, mapping, &index))
884 check_move_unevictable_pages(&pvec);
885 pagevec_release(&pvec);
891 * Check whether a hole-punch or truncation needs to split a huge page,
892 * returning true if no split was required, or the split has been successful.
894 * Eviction (or truncation to 0 size) should never need to split a huge page;
895 * but in rare cases might do so, if shmem_undo_range() failed to trylock on
896 * head, and then succeeded to trylock on tail.
898 * A split can only succeed when there are no additional references on the
899 * huge page: so the split below relies upon find_get_entries() having stopped
900 * when it found a subpage of the huge page, without getting further references.
902 static bool shmem_punch_compound(struct page *page, pgoff_t start, pgoff_t end)
904 if (!PageTransCompound(page))
907 /* Just proceed to delete a huge page wholly within the range punched */
908 if (PageHead(page) &&
909 page->index >= start && page->index + HPAGE_PMD_NR <= end)
912 /* Try to split huge page, so we can truly punch the hole or truncate */
913 return split_huge_page(page) >= 0;
917 * Remove range of pages and swap entries from page cache, and free them.
918 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
920 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
923 struct address_space *mapping = inode->i_mapping;
924 struct shmem_inode_info *info = SHMEM_I(inode);
925 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
926 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
927 unsigned int partial_start = lstart & (PAGE_SIZE - 1);
928 unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
930 pgoff_t indices[PAGEVEC_SIZE];
931 long nr_swaps_freed = 0;
936 end = -1; /* unsigned, so actually very big */
938 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
939 info->fallocend = start;
943 while (index < end && find_lock_entries(mapping, index, end - 1,
945 for (i = 0; i < pagevec_count(&pvec); i++) {
946 struct page *page = pvec.pages[i];
950 if (xa_is_value(page)) {
953 nr_swaps_freed += !shmem_free_swap(mapping,
957 index += thp_nr_pages(page) - 1;
959 if (!unfalloc || !PageUptodate(page))
960 truncate_inode_page(mapping, page);
963 pagevec_remove_exceptionals(&pvec);
964 pagevec_release(&pvec);
970 struct page *page = NULL;
971 shmem_getpage(inode, start - 1, &page, SGP_READ);
973 unsigned int top = PAGE_SIZE;
978 zero_user_segment(page, partial_start, top);
979 set_page_dirty(page);
985 struct page *page = NULL;
986 shmem_getpage(inode, end, &page, SGP_READ);
988 zero_user_segment(page, 0, partial_end);
989 set_page_dirty(page);
998 while (index < end) {
1001 if (!find_get_entries(mapping, index, end - 1, &pvec,
1003 /* If all gone or hole-punch or unfalloc, we're done */
1004 if (index == start || end != -1)
1006 /* But if truncating, restart to make sure all gone */
1010 for (i = 0; i < pagevec_count(&pvec); i++) {
1011 struct page *page = pvec.pages[i];
1014 if (xa_is_value(page)) {
1017 if (shmem_free_swap(mapping, index, page)) {
1018 /* Swap was replaced by page: retry */
1028 if (!unfalloc || !PageUptodate(page)) {
1029 if (page_mapping(page) != mapping) {
1030 /* Page was replaced by swap: retry */
1035 VM_BUG_ON_PAGE(PageWriteback(page), page);
1036 if (shmem_punch_compound(page, start, end))
1037 truncate_inode_page(mapping, page);
1038 else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1039 /* Wipe the page and don't get stuck */
1040 clear_highpage(page);
1041 flush_dcache_page(page);
1042 set_page_dirty(page);
1044 round_up(start, HPAGE_PMD_NR))
1050 pagevec_remove_exceptionals(&pvec);
1051 pagevec_release(&pvec);
1055 spin_lock_irq(&info->lock);
1056 info->swapped -= nr_swaps_freed;
1057 shmem_recalc_inode(inode);
1058 spin_unlock_irq(&info->lock);
1061 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1063 shmem_undo_range(inode, lstart, lend, false);
1064 inode->i_ctime = inode->i_mtime = current_time(inode);
1066 EXPORT_SYMBOL_GPL(shmem_truncate_range);
1068 static int shmem_getattr(struct user_namespace *mnt_userns,
1069 const struct path *path, struct kstat *stat,
1070 u32 request_mask, unsigned int query_flags)
1072 struct inode *inode = path->dentry->d_inode;
1073 struct shmem_inode_info *info = SHMEM_I(inode);
1075 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
1076 spin_lock_irq(&info->lock);
1077 shmem_recalc_inode(inode);
1078 spin_unlock_irq(&info->lock);
1080 generic_fillattr(&init_user_ns, inode, stat);
1082 if (shmem_is_huge(NULL, inode, 0))
1083 stat->blksize = HPAGE_PMD_SIZE;
1088 static int shmem_setattr(struct user_namespace *mnt_userns,
1089 struct dentry *dentry, struct iattr *attr)
1091 struct inode *inode = d_inode(dentry);
1092 struct shmem_inode_info *info = SHMEM_I(inode);
1095 error = setattr_prepare(&init_user_ns, dentry, attr);
1099 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1100 loff_t oldsize = inode->i_size;
1101 loff_t newsize = attr->ia_size;
1103 /* protected by i_rwsem */
1104 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1105 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1108 if (newsize != oldsize) {
1109 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1113 i_size_write(inode, newsize);
1114 inode->i_ctime = inode->i_mtime = current_time(inode);
1116 if (newsize <= oldsize) {
1117 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1118 if (oldsize > holebegin)
1119 unmap_mapping_range(inode->i_mapping,
1122 shmem_truncate_range(inode,
1123 newsize, (loff_t)-1);
1124 /* unmap again to remove racily COWed private pages */
1125 if (oldsize > holebegin)
1126 unmap_mapping_range(inode->i_mapping,
1131 setattr_copy(&init_user_ns, inode, attr);
1132 if (attr->ia_valid & ATTR_MODE)
1133 error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
1137 static void shmem_evict_inode(struct inode *inode)
1139 struct shmem_inode_info *info = SHMEM_I(inode);
1140 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1142 if (shmem_mapping(inode->i_mapping)) {
1143 shmem_unacct_size(info->flags, inode->i_size);
1145 shmem_truncate_range(inode, 0, (loff_t)-1);
1146 if (!list_empty(&info->shrinklist)) {
1147 spin_lock(&sbinfo->shrinklist_lock);
1148 if (!list_empty(&info->shrinklist)) {
1149 list_del_init(&info->shrinklist);
1150 sbinfo->shrinklist_len--;
1152 spin_unlock(&sbinfo->shrinklist_lock);
1154 while (!list_empty(&info->swaplist)) {
1155 /* Wait while shmem_unuse() is scanning this inode... */
1156 wait_var_event(&info->stop_eviction,
1157 !atomic_read(&info->stop_eviction));
1158 mutex_lock(&shmem_swaplist_mutex);
1159 /* ...but beware of the race if we peeked too early */
1160 if (!atomic_read(&info->stop_eviction))
1161 list_del_init(&info->swaplist);
1162 mutex_unlock(&shmem_swaplist_mutex);
1166 simple_xattrs_free(&info->xattrs);
1167 WARN_ON(inode->i_blocks);
1168 shmem_free_inode(inode->i_sb);
1172 static int shmem_find_swap_entries(struct address_space *mapping,
1173 pgoff_t start, unsigned int nr_entries,
1174 struct page **entries, pgoff_t *indices,
1175 unsigned int type, bool frontswap)
1177 XA_STATE(xas, &mapping->i_pages, start);
1180 unsigned int ret = 0;
1186 xas_for_each(&xas, page, ULONG_MAX) {
1187 if (xas_retry(&xas, page))
1190 if (!xa_is_value(page))
1193 entry = radix_to_swp_entry(page);
1194 if (swp_type(entry) != type)
1197 !frontswap_test(swap_info[type], swp_offset(entry)))
1200 indices[ret] = xas.xa_index;
1201 entries[ret] = page;
1203 if (need_resched()) {
1207 if (++ret == nr_entries)
1216 * Move the swapped pages for an inode to page cache. Returns the count
1217 * of pages swapped in, or the error in case of failure.
1219 static int shmem_unuse_swap_entries(struct inode *inode, struct pagevec pvec,
1225 struct address_space *mapping = inode->i_mapping;
1227 for (i = 0; i < pvec.nr; i++) {
1228 struct page *page = pvec.pages[i];
1230 if (!xa_is_value(page))
1232 error = shmem_swapin_page(inode, indices[i],
1234 mapping_gfp_mask(mapping),
1241 if (error == -ENOMEM)
1245 return error ? error : ret;
1249 * If swap found in inode, free it and move page from swapcache to filecache.
1251 static int shmem_unuse_inode(struct inode *inode, unsigned int type,
1252 bool frontswap, unsigned long *fs_pages_to_unuse)
1254 struct address_space *mapping = inode->i_mapping;
1256 struct pagevec pvec;
1257 pgoff_t indices[PAGEVEC_SIZE];
1258 bool frontswap_partial = (frontswap && *fs_pages_to_unuse > 0);
1261 pagevec_init(&pvec);
1263 unsigned int nr_entries = PAGEVEC_SIZE;
1265 if (frontswap_partial && *fs_pages_to_unuse < PAGEVEC_SIZE)
1266 nr_entries = *fs_pages_to_unuse;
1268 pvec.nr = shmem_find_swap_entries(mapping, start, nr_entries,
1269 pvec.pages, indices,
1276 ret = shmem_unuse_swap_entries(inode, pvec, indices);
1280 if (frontswap_partial) {
1281 *fs_pages_to_unuse -= ret;
1282 if (*fs_pages_to_unuse == 0) {
1283 ret = FRONTSWAP_PAGES_UNUSED;
1288 start = indices[pvec.nr - 1];
1295 * Read all the shared memory data that resides in the swap
1296 * device 'type' back into memory, so the swap device can be
1299 int shmem_unuse(unsigned int type, bool frontswap,
1300 unsigned long *fs_pages_to_unuse)
1302 struct shmem_inode_info *info, *next;
1305 if (list_empty(&shmem_swaplist))
1308 mutex_lock(&shmem_swaplist_mutex);
1309 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1310 if (!info->swapped) {
1311 list_del_init(&info->swaplist);
1315 * Drop the swaplist mutex while searching the inode for swap;
1316 * but before doing so, make sure shmem_evict_inode() will not
1317 * remove placeholder inode from swaplist, nor let it be freed
1318 * (igrab() would protect from unlink, but not from unmount).
1320 atomic_inc(&info->stop_eviction);
1321 mutex_unlock(&shmem_swaplist_mutex);
1323 error = shmem_unuse_inode(&info->vfs_inode, type, frontswap,
1327 mutex_lock(&shmem_swaplist_mutex);
1328 next = list_next_entry(info, swaplist);
1330 list_del_init(&info->swaplist);
1331 if (atomic_dec_and_test(&info->stop_eviction))
1332 wake_up_var(&info->stop_eviction);
1336 mutex_unlock(&shmem_swaplist_mutex);
1342 * Move the page from the page cache to the swap cache.
1344 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1346 struct shmem_inode_info *info;
1347 struct address_space *mapping;
1348 struct inode *inode;
1353 * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or
1354 * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages,
1355 * and its shmem_writeback() needs them to be split when swapping.
1357 if (PageTransCompound(page)) {
1358 /* Ensure the subpages are still dirty */
1360 if (split_huge_page(page) < 0)
1362 ClearPageDirty(page);
1365 BUG_ON(!PageLocked(page));
1366 mapping = page->mapping;
1367 index = page->index;
1368 inode = mapping->host;
1369 info = SHMEM_I(inode);
1370 if (info->flags & VM_LOCKED)
1372 if (!total_swap_pages)
1376 * Our capabilities prevent regular writeback or sync from ever calling
1377 * shmem_writepage; but a stacking filesystem might use ->writepage of
1378 * its underlying filesystem, in which case tmpfs should write out to
1379 * swap only in response to memory pressure, and not for the writeback
1382 if (!wbc->for_reclaim) {
1383 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1388 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1389 * value into swapfile.c, the only way we can correctly account for a
1390 * fallocated page arriving here is now to initialize it and write it.
1392 * That's okay for a page already fallocated earlier, but if we have
1393 * not yet completed the fallocation, then (a) we want to keep track
1394 * of this page in case we have to undo it, and (b) it may not be a
1395 * good idea to continue anyway, once we're pushing into swap. So
1396 * reactivate the page, and let shmem_fallocate() quit when too many.
1398 if (!PageUptodate(page)) {
1399 if (inode->i_private) {
1400 struct shmem_falloc *shmem_falloc;
1401 spin_lock(&inode->i_lock);
1402 shmem_falloc = inode->i_private;
1404 !shmem_falloc->waitq &&
1405 index >= shmem_falloc->start &&
1406 index < shmem_falloc->next)
1407 shmem_falloc->nr_unswapped++;
1409 shmem_falloc = NULL;
1410 spin_unlock(&inode->i_lock);
1414 clear_highpage(page);
1415 flush_dcache_page(page);
1416 SetPageUptodate(page);
1419 swap = get_swap_page(page);
1424 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1425 * if it's not already there. Do it now before the page is
1426 * moved to swap cache, when its pagelock no longer protects
1427 * the inode from eviction. But don't unlock the mutex until
1428 * we've incremented swapped, because shmem_unuse_inode() will
1429 * prune a !swapped inode from the swaplist under this mutex.
1431 mutex_lock(&shmem_swaplist_mutex);
1432 if (list_empty(&info->swaplist))
1433 list_add(&info->swaplist, &shmem_swaplist);
1435 if (add_to_swap_cache(page, swap,
1436 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1438 spin_lock_irq(&info->lock);
1439 shmem_recalc_inode(inode);
1441 spin_unlock_irq(&info->lock);
1443 swap_shmem_alloc(swap);
1444 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1446 mutex_unlock(&shmem_swaplist_mutex);
1447 BUG_ON(page_mapped(page));
1448 swap_writepage(page, wbc);
1452 mutex_unlock(&shmem_swaplist_mutex);
1453 put_swap_page(page, swap);
1455 set_page_dirty(page);
1456 if (wbc->for_reclaim)
1457 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1462 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1463 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1467 if (!mpol || mpol->mode == MPOL_DEFAULT)
1468 return; /* show nothing */
1470 mpol_to_str(buffer, sizeof(buffer), mpol);
1472 seq_printf(seq, ",mpol=%s", buffer);
1475 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1477 struct mempolicy *mpol = NULL;
1479 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1480 mpol = sbinfo->mpol;
1482 raw_spin_unlock(&sbinfo->stat_lock);
1486 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1487 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1490 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1494 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1496 #define vm_policy vm_private_data
1499 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1500 struct shmem_inode_info *info, pgoff_t index)
1502 /* Create a pseudo vma that just contains the policy */
1503 vma_init(vma, NULL);
1504 /* Bias interleave by inode number to distribute better across nodes */
1505 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1506 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1509 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1511 /* Drop reference taken by mpol_shared_policy_lookup() */
1512 mpol_cond_put(vma->vm_policy);
1515 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1516 struct shmem_inode_info *info, pgoff_t index)
1518 struct vm_area_struct pvma;
1520 struct vm_fault vmf = {
1524 shmem_pseudo_vma_init(&pvma, info, index);
1525 page = swap_cluster_readahead(swap, gfp, &vmf);
1526 shmem_pseudo_vma_destroy(&pvma);
1532 * Make sure huge_gfp is always more limited than limit_gfp.
1533 * Some of the flags set permissions, while others set limitations.
1535 static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1537 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1538 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1539 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1540 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1542 /* Allow allocations only from the originally specified zones. */
1543 result |= zoneflags;
1546 * Minimize the result gfp by taking the union with the deny flags,
1547 * and the intersection of the allow flags.
1549 result |= (limit_gfp & denyflags);
1550 result |= (huge_gfp & limit_gfp) & allowflags;
1555 static struct page *shmem_alloc_hugepage(gfp_t gfp,
1556 struct shmem_inode_info *info, pgoff_t index)
1558 struct vm_area_struct pvma;
1559 struct address_space *mapping = info->vfs_inode.i_mapping;
1563 hindex = round_down(index, HPAGE_PMD_NR);
1564 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1568 shmem_pseudo_vma_init(&pvma, info, hindex);
1569 page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(),
1571 shmem_pseudo_vma_destroy(&pvma);
1573 prep_transhuge_page(page);
1575 count_vm_event(THP_FILE_FALLBACK);
1579 static struct page *shmem_alloc_page(gfp_t gfp,
1580 struct shmem_inode_info *info, pgoff_t index)
1582 struct vm_area_struct pvma;
1585 shmem_pseudo_vma_init(&pvma, info, index);
1586 page = alloc_page_vma(gfp, &pvma, 0);
1587 shmem_pseudo_vma_destroy(&pvma);
1592 static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1593 struct inode *inode,
1594 pgoff_t index, bool huge)
1596 struct shmem_inode_info *info = SHMEM_I(inode);
1601 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1603 nr = huge ? HPAGE_PMD_NR : 1;
1605 if (!shmem_inode_acct_block(inode, nr))
1609 page = shmem_alloc_hugepage(gfp, info, index);
1611 page = shmem_alloc_page(gfp, info, index);
1613 __SetPageLocked(page);
1614 __SetPageSwapBacked(page);
1619 shmem_inode_unacct_blocks(inode, nr);
1621 return ERR_PTR(err);
1625 * When a page is moved from swapcache to shmem filecache (either by the
1626 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1627 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1628 * ignorance of the mapping it belongs to. If that mapping has special
1629 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1630 * we may need to copy to a suitable page before moving to filecache.
1632 * In a future release, this may well be extended to respect cpuset and
1633 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1634 * but for now it is a simple matter of zone.
1636 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1638 return page_zonenum(page) > gfp_zone(gfp);
1641 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1642 struct shmem_inode_info *info, pgoff_t index)
1644 struct page *oldpage, *newpage;
1645 struct address_space *swap_mapping;
1651 entry.val = page_private(oldpage);
1652 swap_index = swp_offset(entry);
1653 swap_mapping = page_mapping(oldpage);
1656 * We have arrived here because our zones are constrained, so don't
1657 * limit chance of success by further cpuset and node constraints.
1659 gfp &= ~GFP_CONSTRAINT_MASK;
1660 newpage = shmem_alloc_page(gfp, info, index);
1665 copy_highpage(newpage, oldpage);
1666 flush_dcache_page(newpage);
1668 __SetPageLocked(newpage);
1669 __SetPageSwapBacked(newpage);
1670 SetPageUptodate(newpage);
1671 set_page_private(newpage, entry.val);
1672 SetPageSwapCache(newpage);
1675 * Our caller will very soon move newpage out of swapcache, but it's
1676 * a nice clean interface for us to replace oldpage by newpage there.
1678 xa_lock_irq(&swap_mapping->i_pages);
1679 error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
1681 mem_cgroup_migrate(oldpage, newpage);
1682 __inc_lruvec_page_state(newpage, NR_FILE_PAGES);
1683 __dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
1685 xa_unlock_irq(&swap_mapping->i_pages);
1687 if (unlikely(error)) {
1689 * Is this possible? I think not, now that our callers check
1690 * both PageSwapCache and page_private after getting page lock;
1691 * but be defensive. Reverse old to newpage for clear and free.
1695 lru_cache_add(newpage);
1699 ClearPageSwapCache(oldpage);
1700 set_page_private(oldpage, 0);
1702 unlock_page(oldpage);
1709 * Swap in the page pointed to by *pagep.
1710 * Caller has to make sure that *pagep contains a valid swapped page.
1711 * Returns 0 and the page in pagep if success. On failure, returns the
1712 * error code and NULL in *pagep.
1714 static int shmem_swapin_page(struct inode *inode, pgoff_t index,
1715 struct page **pagep, enum sgp_type sgp,
1716 gfp_t gfp, struct vm_area_struct *vma,
1717 vm_fault_t *fault_type)
1719 struct address_space *mapping = inode->i_mapping;
1720 struct shmem_inode_info *info = SHMEM_I(inode);
1721 struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
1726 VM_BUG_ON(!*pagep || !xa_is_value(*pagep));
1727 swap = radix_to_swp_entry(*pagep);
1730 /* Look it up and read it in.. */
1731 page = lookup_swap_cache(swap, NULL, 0);
1733 /* Or update major stats only when swapin succeeds?? */
1735 *fault_type |= VM_FAULT_MAJOR;
1736 count_vm_event(PGMAJFAULT);
1737 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1739 /* Here we actually start the io */
1740 page = shmem_swapin(swap, gfp, info, index);
1747 /* We have to do this with page locked to prevent races */
1749 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1750 !shmem_confirm_swap(mapping, index, swap)) {
1754 if (!PageUptodate(page)) {
1758 wait_on_page_writeback(page);
1761 * Some architectures may have to restore extra metadata to the
1762 * physical page after reading from swap.
1764 arch_swap_restore(swap, page);
1766 if (shmem_should_replace_page(page, gfp)) {
1767 error = shmem_replace_page(&page, gfp, info, index);
1772 error = shmem_add_to_page_cache(page, mapping, index,
1773 swp_to_radix_entry(swap), gfp,
1778 spin_lock_irq(&info->lock);
1780 shmem_recalc_inode(inode);
1781 spin_unlock_irq(&info->lock);
1783 if (sgp == SGP_WRITE)
1784 mark_page_accessed(page);
1786 delete_from_swap_cache(page);
1787 set_page_dirty(page);
1793 if (!shmem_confirm_swap(mapping, index, swap))
1805 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1807 * If we allocate a new one we do not mark it dirty. That's up to the
1808 * vm. If we swap it in we mark it dirty since we also free the swap
1809 * entry since a page cannot live in both the swap and page cache.
1811 * vma, vmf, and fault_type are only supplied by shmem_fault:
1812 * otherwise they are NULL.
1814 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1815 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1816 struct vm_area_struct *vma, struct vm_fault *vmf,
1817 vm_fault_t *fault_type)
1819 struct address_space *mapping = inode->i_mapping;
1820 struct shmem_inode_info *info = SHMEM_I(inode);
1821 struct shmem_sb_info *sbinfo;
1822 struct mm_struct *charge_mm;
1824 pgoff_t hindex = index;
1830 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1833 if (sgp <= SGP_CACHE &&
1834 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1838 sbinfo = SHMEM_SB(inode->i_sb);
1839 charge_mm = vma ? vma->vm_mm : NULL;
1841 page = pagecache_get_page(mapping, index,
1842 FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0);
1844 if (page && vma && userfaultfd_minor(vma)) {
1845 if (!xa_is_value(page)) {
1849 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
1853 if (xa_is_value(page)) {
1854 error = shmem_swapin_page(inode, index, &page,
1855 sgp, gfp, vma, fault_type);
1856 if (error == -EEXIST)
1864 hindex = page->index;
1865 if (sgp == SGP_WRITE)
1866 mark_page_accessed(page);
1867 if (PageUptodate(page))
1869 /* fallocated page */
1870 if (sgp != SGP_READ)
1877 * SGP_READ: succeed on hole, with NULL page, letting caller zero.
1878 * SGP_NOALLOC: fail on hole, with NULL page, letting caller fail.
1881 if (sgp == SGP_READ)
1883 if (sgp == SGP_NOALLOC)
1887 * Fast cache lookup and swap lookup did not find it: allocate.
1890 if (vma && userfaultfd_missing(vma)) {
1891 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1895 /* Never use a huge page for shmem_symlink() */
1896 if (S_ISLNK(inode->i_mode))
1898 if (!shmem_is_huge(vma, inode, index))
1901 huge_gfp = vma_thp_gfp_mask(vma);
1902 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
1903 page = shmem_alloc_and_acct_page(huge_gfp, inode, index, true);
1906 page = shmem_alloc_and_acct_page(gfp, inode,
1912 error = PTR_ERR(page);
1914 if (error != -ENOSPC)
1917 * Try to reclaim some space by splitting a huge page
1918 * beyond i_size on the filesystem.
1923 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1924 if (ret == SHRINK_STOP)
1932 if (PageTransHuge(page))
1933 hindex = round_down(index, HPAGE_PMD_NR);
1937 if (sgp == SGP_WRITE)
1938 __SetPageReferenced(page);
1940 error = shmem_add_to_page_cache(page, mapping, hindex,
1941 NULL, gfp & GFP_RECLAIM_MASK,
1945 lru_cache_add(page);
1947 spin_lock_irq(&info->lock);
1948 info->alloced += compound_nr(page);
1949 inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1950 shmem_recalc_inode(inode);
1951 spin_unlock_irq(&info->lock);
1954 if (PageTransHuge(page) &&
1955 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1956 hindex + HPAGE_PMD_NR - 1) {
1958 * Part of the huge page is beyond i_size: subject
1959 * to shrink under memory pressure.
1961 spin_lock(&sbinfo->shrinklist_lock);
1963 * _careful to defend against unlocked access to
1964 * ->shrink_list in shmem_unused_huge_shrink()
1966 if (list_empty_careful(&info->shrinklist)) {
1967 list_add_tail(&info->shrinklist,
1968 &sbinfo->shrinklist);
1969 sbinfo->shrinklist_len++;
1971 spin_unlock(&sbinfo->shrinklist_lock);
1975 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1977 if (sgp == SGP_FALLOC)
1981 * Let SGP_WRITE caller clear ends if write does not fill page;
1982 * but SGP_FALLOC on a page fallocated earlier must initialize
1983 * it now, lest undo on failure cancel our earlier guarantee.
1985 if (sgp != SGP_WRITE && !PageUptodate(page)) {
1988 for (i = 0; i < compound_nr(page); i++) {
1989 clear_highpage(page + i);
1990 flush_dcache_page(page + i);
1992 SetPageUptodate(page);
1995 /* Perhaps the file has been truncated since we checked */
1996 if (sgp <= SGP_CACHE &&
1997 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1999 ClearPageDirty(page);
2000 delete_from_page_cache(page);
2001 spin_lock_irq(&info->lock);
2002 shmem_recalc_inode(inode);
2003 spin_unlock_irq(&info->lock);
2009 *pagep = page + index - hindex;
2016 shmem_inode_unacct_blocks(inode, compound_nr(page));
2018 if (PageTransHuge(page)) {
2028 if (error == -ENOSPC && !once++) {
2029 spin_lock_irq(&info->lock);
2030 shmem_recalc_inode(inode);
2031 spin_unlock_irq(&info->lock);
2034 if (error == -EEXIST)
2040 * This is like autoremove_wake_function, but it removes the wait queue
2041 * entry unconditionally - even if something else had already woken the
2044 static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
2046 int ret = default_wake_function(wait, mode, sync, key);
2047 list_del_init(&wait->entry);
2051 static vm_fault_t shmem_fault(struct vm_fault *vmf)
2053 struct vm_area_struct *vma = vmf->vma;
2054 struct inode *inode = file_inode(vma->vm_file);
2055 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2057 vm_fault_t ret = VM_FAULT_LOCKED;
2060 * Trinity finds that probing a hole which tmpfs is punching can
2061 * prevent the hole-punch from ever completing: which in turn
2062 * locks writers out with its hold on i_rwsem. So refrain from
2063 * faulting pages into the hole while it's being punched. Although
2064 * shmem_undo_range() does remove the additions, it may be unable to
2065 * keep up, as each new page needs its own unmap_mapping_range() call,
2066 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2068 * It does not matter if we sometimes reach this check just before the
2069 * hole-punch begins, so that one fault then races with the punch:
2070 * we just need to make racing faults a rare case.
2072 * The implementation below would be much simpler if we just used a
2073 * standard mutex or completion: but we cannot take i_rwsem in fault,
2074 * and bloating every shmem inode for this unlikely case would be sad.
2076 if (unlikely(inode->i_private)) {
2077 struct shmem_falloc *shmem_falloc;
2079 spin_lock(&inode->i_lock);
2080 shmem_falloc = inode->i_private;
2082 shmem_falloc->waitq &&
2083 vmf->pgoff >= shmem_falloc->start &&
2084 vmf->pgoff < shmem_falloc->next) {
2086 wait_queue_head_t *shmem_falloc_waitq;
2087 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2089 ret = VM_FAULT_NOPAGE;
2090 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2092 ret = VM_FAULT_RETRY;
2094 shmem_falloc_waitq = shmem_falloc->waitq;
2095 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2096 TASK_UNINTERRUPTIBLE);
2097 spin_unlock(&inode->i_lock);
2101 * shmem_falloc_waitq points into the shmem_fallocate()
2102 * stack of the hole-punching task: shmem_falloc_waitq
2103 * is usually invalid by the time we reach here, but
2104 * finish_wait() does not dereference it in that case;
2105 * though i_lock needed lest racing with wake_up_all().
2107 spin_lock(&inode->i_lock);
2108 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2109 spin_unlock(&inode->i_lock);
2115 spin_unlock(&inode->i_lock);
2118 err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE,
2119 gfp, vma, vmf, &ret);
2121 return vmf_error(err);
2125 unsigned long shmem_get_unmapped_area(struct file *file,
2126 unsigned long uaddr, unsigned long len,
2127 unsigned long pgoff, unsigned long flags)
2129 unsigned long (*get_area)(struct file *,
2130 unsigned long, unsigned long, unsigned long, unsigned long);
2132 unsigned long offset;
2133 unsigned long inflated_len;
2134 unsigned long inflated_addr;
2135 unsigned long inflated_offset;
2137 if (len > TASK_SIZE)
2140 get_area = current->mm->get_unmapped_area;
2141 addr = get_area(file, uaddr, len, pgoff, flags);
2143 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2145 if (IS_ERR_VALUE(addr))
2147 if (addr & ~PAGE_MASK)
2149 if (addr > TASK_SIZE - len)
2152 if (shmem_huge == SHMEM_HUGE_DENY)
2154 if (len < HPAGE_PMD_SIZE)
2156 if (flags & MAP_FIXED)
2159 * Our priority is to support MAP_SHARED mapped hugely;
2160 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2161 * But if caller specified an address hint and we allocated area there
2162 * successfully, respect that as before.
2167 if (shmem_huge != SHMEM_HUGE_FORCE) {
2168 struct super_block *sb;
2171 VM_BUG_ON(file->f_op != &shmem_file_operations);
2172 sb = file_inode(file)->i_sb;
2175 * Called directly from mm/mmap.c, or drivers/char/mem.c
2176 * for "/dev/zero", to create a shared anonymous object.
2178 if (IS_ERR(shm_mnt))
2180 sb = shm_mnt->mnt_sb;
2182 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2186 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2187 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2189 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2192 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2193 if (inflated_len > TASK_SIZE)
2195 if (inflated_len < len)
2198 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2199 if (IS_ERR_VALUE(inflated_addr))
2201 if (inflated_addr & ~PAGE_MASK)
2204 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2205 inflated_addr += offset - inflated_offset;
2206 if (inflated_offset > offset)
2207 inflated_addr += HPAGE_PMD_SIZE;
2209 if (inflated_addr > TASK_SIZE - len)
2211 return inflated_addr;
2215 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2217 struct inode *inode = file_inode(vma->vm_file);
2218 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2221 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2224 struct inode *inode = file_inode(vma->vm_file);
2227 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2228 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2232 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2234 struct inode *inode = file_inode(file);
2235 struct shmem_inode_info *info = SHMEM_I(inode);
2236 int retval = -ENOMEM;
2239 * What serializes the accesses to info->flags?
2240 * ipc_lock_object() when called from shmctl_do_lock(),
2241 * no serialization needed when called from shm_destroy().
2243 if (lock && !(info->flags & VM_LOCKED)) {
2244 if (!user_shm_lock(inode->i_size, ucounts))
2246 info->flags |= VM_LOCKED;
2247 mapping_set_unevictable(file->f_mapping);
2249 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2250 user_shm_unlock(inode->i_size, ucounts);
2251 info->flags &= ~VM_LOCKED;
2252 mapping_clear_unevictable(file->f_mapping);
2260 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2262 struct shmem_inode_info *info = SHMEM_I(file_inode(file));
2265 ret = seal_check_future_write(info->seals, vma);
2269 /* arm64 - allow memory tagging on RAM-based files */
2270 vma->vm_flags |= VM_MTE_ALLOWED;
2272 file_accessed(file);
2273 vma->vm_ops = &shmem_vm_ops;
2274 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
2275 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2276 (vma->vm_end & HPAGE_PMD_MASK)) {
2277 khugepaged_enter(vma, vma->vm_flags);
2282 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2283 umode_t mode, dev_t dev, unsigned long flags)
2285 struct inode *inode;
2286 struct shmem_inode_info *info;
2287 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2290 if (shmem_reserve_inode(sb, &ino))
2293 inode = new_inode(sb);
2296 inode_init_owner(&init_user_ns, inode, dir, mode);
2297 inode->i_blocks = 0;
2298 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2299 inode->i_generation = prandom_u32();
2300 info = SHMEM_I(inode);
2301 memset(info, 0, (char *)inode - (char *)info);
2302 spin_lock_init(&info->lock);
2303 atomic_set(&info->stop_eviction, 0);
2304 info->seals = F_SEAL_SEAL;
2305 info->flags = flags & VM_NORESERVE;
2306 INIT_LIST_HEAD(&info->shrinklist);
2307 INIT_LIST_HEAD(&info->swaplist);
2308 simple_xattrs_init(&info->xattrs);
2309 cache_no_acl(inode);
2311 switch (mode & S_IFMT) {
2313 inode->i_op = &shmem_special_inode_operations;
2314 init_special_inode(inode, mode, dev);
2317 inode->i_mapping->a_ops = &shmem_aops;
2318 inode->i_op = &shmem_inode_operations;
2319 inode->i_fop = &shmem_file_operations;
2320 mpol_shared_policy_init(&info->policy,
2321 shmem_get_sbmpol(sbinfo));
2325 /* Some things misbehave if size == 0 on a directory */
2326 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2327 inode->i_op = &shmem_dir_inode_operations;
2328 inode->i_fop = &simple_dir_operations;
2332 * Must not load anything in the rbtree,
2333 * mpol_free_shared_policy will not be called.
2335 mpol_shared_policy_init(&info->policy, NULL);
2339 lockdep_annotate_inode_mutex_key(inode);
2341 shmem_free_inode(sb);
2345 #ifdef CONFIG_USERFAULTFD
2346 int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2348 struct vm_area_struct *dst_vma,
2349 unsigned long dst_addr,
2350 unsigned long src_addr,
2352 struct page **pagep)
2354 struct inode *inode = file_inode(dst_vma->vm_file);
2355 struct shmem_inode_info *info = SHMEM_I(inode);
2356 struct address_space *mapping = inode->i_mapping;
2357 gfp_t gfp = mapping_gfp_mask(mapping);
2358 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2364 if (!shmem_inode_acct_block(inode, 1)) {
2366 * We may have got a page, returned -ENOENT triggering a retry,
2367 * and now we find ourselves with -ENOMEM. Release the page, to
2368 * avoid a BUG_ON in our caller.
2370 if (unlikely(*pagep)) {
2379 page = shmem_alloc_page(gfp, info, pgoff);
2381 goto out_unacct_blocks;
2383 if (!zeropage) { /* COPY */
2384 page_kaddr = kmap_atomic(page);
2385 ret = copy_from_user(page_kaddr,
2386 (const void __user *)src_addr,
2388 kunmap_atomic(page_kaddr);
2390 /* fallback to copy_from_user outside mmap_lock */
2391 if (unlikely(ret)) {
2394 /* don't free the page */
2395 goto out_unacct_blocks;
2398 flush_dcache_page(page);
2399 } else { /* ZEROPAGE */
2400 clear_user_highpage(page, dst_addr);
2407 VM_BUG_ON(PageLocked(page));
2408 VM_BUG_ON(PageSwapBacked(page));
2409 __SetPageLocked(page);
2410 __SetPageSwapBacked(page);
2411 __SetPageUptodate(page);
2414 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2415 if (unlikely(pgoff >= max_off))
2418 ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL,
2419 gfp & GFP_RECLAIM_MASK, dst_mm);
2423 ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
2426 goto out_delete_from_cache;
2428 spin_lock_irq(&info->lock);
2430 inode->i_blocks += BLOCKS_PER_PAGE;
2431 shmem_recalc_inode(inode);
2432 spin_unlock_irq(&info->lock);
2437 out_delete_from_cache:
2438 delete_from_page_cache(page);
2443 shmem_inode_unacct_blocks(inode, 1);
2446 #endif /* CONFIG_USERFAULTFD */
2449 static const struct inode_operations shmem_symlink_inode_operations;
2450 static const struct inode_operations shmem_short_symlink_operations;
2452 #ifdef CONFIG_TMPFS_XATTR
2453 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2455 #define shmem_initxattrs NULL
2459 shmem_write_begin(struct file *file, struct address_space *mapping,
2460 loff_t pos, unsigned len, unsigned flags,
2461 struct page **pagep, void **fsdata)
2463 struct inode *inode = mapping->host;
2464 struct shmem_inode_info *info = SHMEM_I(inode);
2465 pgoff_t index = pos >> PAGE_SHIFT;
2468 /* i_rwsem is held by caller */
2469 if (unlikely(info->seals & (F_SEAL_GROW |
2470 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2471 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2473 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2477 ret = shmem_getpage(inode, index, pagep, SGP_WRITE);
2482 if (PageHWPoison(*pagep)) {
2483 unlock_page(*pagep);
2493 shmem_write_end(struct file *file, struct address_space *mapping,
2494 loff_t pos, unsigned len, unsigned copied,
2495 struct page *page, void *fsdata)
2497 struct inode *inode = mapping->host;
2499 if (pos + copied > inode->i_size)
2500 i_size_write(inode, pos + copied);
2502 if (!PageUptodate(page)) {
2503 struct page *head = compound_head(page);
2504 if (PageTransCompound(page)) {
2507 for (i = 0; i < HPAGE_PMD_NR; i++) {
2508 if (head + i == page)
2510 clear_highpage(head + i);
2511 flush_dcache_page(head + i);
2514 if (copied < PAGE_SIZE) {
2515 unsigned from = pos & (PAGE_SIZE - 1);
2516 zero_user_segments(page, 0, from,
2517 from + copied, PAGE_SIZE);
2519 SetPageUptodate(head);
2521 set_page_dirty(page);
2528 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2530 struct file *file = iocb->ki_filp;
2531 struct inode *inode = file_inode(file);
2532 struct address_space *mapping = inode->i_mapping;
2534 unsigned long offset;
2535 enum sgp_type sgp = SGP_READ;
2538 loff_t *ppos = &iocb->ki_pos;
2541 * Might this read be for a stacking filesystem? Then when reading
2542 * holes of a sparse file, we actually need to allocate those pages,
2543 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2545 if (!iter_is_iovec(to))
2548 index = *ppos >> PAGE_SHIFT;
2549 offset = *ppos & ~PAGE_MASK;
2552 struct page *page = NULL;
2554 unsigned long nr, ret;
2555 loff_t i_size = i_size_read(inode);
2557 end_index = i_size >> PAGE_SHIFT;
2558 if (index > end_index)
2560 if (index == end_index) {
2561 nr = i_size & ~PAGE_MASK;
2566 error = shmem_getpage(inode, index, &page, sgp);
2568 if (error == -EINVAL)
2573 if (sgp == SGP_CACHE)
2574 set_page_dirty(page);
2577 if (PageHWPoison(page)) {
2585 * We must evaluate after, since reads (unlike writes)
2586 * are called without i_rwsem protection against truncate
2589 i_size = i_size_read(inode);
2590 end_index = i_size >> PAGE_SHIFT;
2591 if (index == end_index) {
2592 nr = i_size & ~PAGE_MASK;
2603 * If users can be writing to this page using arbitrary
2604 * virtual addresses, take care about potential aliasing
2605 * before reading the page on the kernel side.
2607 if (mapping_writably_mapped(mapping))
2608 flush_dcache_page(page);
2610 * Mark the page accessed if we read the beginning.
2613 mark_page_accessed(page);
2615 page = ZERO_PAGE(0);
2620 * Ok, we have the page, and it's up-to-date, so
2621 * now we can copy it to user space...
2623 ret = copy_page_to_iter(page, offset, nr, to);
2626 index += offset >> PAGE_SHIFT;
2627 offset &= ~PAGE_MASK;
2630 if (!iov_iter_count(to))
2639 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2640 file_accessed(file);
2641 return retval ? retval : error;
2644 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2646 struct address_space *mapping = file->f_mapping;
2647 struct inode *inode = mapping->host;
2649 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2650 return generic_file_llseek_size(file, offset, whence,
2651 MAX_LFS_FILESIZE, i_size_read(inode));
2656 /* We're holding i_rwsem so we can access i_size directly */
2657 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
2659 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2660 inode_unlock(inode);
2664 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2667 struct inode *inode = file_inode(file);
2668 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2669 struct shmem_inode_info *info = SHMEM_I(inode);
2670 struct shmem_falloc shmem_falloc;
2671 pgoff_t start, index, end, undo_fallocend;
2674 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2679 if (mode & FALLOC_FL_PUNCH_HOLE) {
2680 struct address_space *mapping = file->f_mapping;
2681 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2682 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2683 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2685 /* protected by i_rwsem */
2686 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
2691 shmem_falloc.waitq = &shmem_falloc_waitq;
2692 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
2693 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2694 spin_lock(&inode->i_lock);
2695 inode->i_private = &shmem_falloc;
2696 spin_unlock(&inode->i_lock);
2698 if ((u64)unmap_end > (u64)unmap_start)
2699 unmap_mapping_range(mapping, unmap_start,
2700 1 + unmap_end - unmap_start, 0);
2701 shmem_truncate_range(inode, offset, offset + len - 1);
2702 /* No need to unmap again: hole-punching leaves COWed pages */
2704 spin_lock(&inode->i_lock);
2705 inode->i_private = NULL;
2706 wake_up_all(&shmem_falloc_waitq);
2707 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2708 spin_unlock(&inode->i_lock);
2713 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2714 error = inode_newsize_ok(inode, offset + len);
2718 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2723 start = offset >> PAGE_SHIFT;
2724 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2725 /* Try to avoid a swapstorm if len is impossible to satisfy */
2726 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2731 shmem_falloc.waitq = NULL;
2732 shmem_falloc.start = start;
2733 shmem_falloc.next = start;
2734 shmem_falloc.nr_falloced = 0;
2735 shmem_falloc.nr_unswapped = 0;
2736 spin_lock(&inode->i_lock);
2737 inode->i_private = &shmem_falloc;
2738 spin_unlock(&inode->i_lock);
2741 * info->fallocend is only relevant when huge pages might be
2742 * involved: to prevent split_huge_page() freeing fallocated
2743 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
2745 undo_fallocend = info->fallocend;
2746 if (info->fallocend < end)
2747 info->fallocend = end;
2749 for (index = start; index < end; ) {
2753 * Good, the fallocate(2) manpage permits EINTR: we may have
2754 * been interrupted because we are using up too much memory.
2756 if (signal_pending(current))
2758 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2761 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2763 info->fallocend = undo_fallocend;
2764 /* Remove the !PageUptodate pages we added */
2765 if (index > start) {
2766 shmem_undo_range(inode,
2767 (loff_t)start << PAGE_SHIFT,
2768 ((loff_t)index << PAGE_SHIFT) - 1, true);
2775 * Here is a more important optimization than it appears:
2776 * a second SGP_FALLOC on the same huge page will clear it,
2777 * making it PageUptodate and un-undoable if we fail later.
2779 if (PageTransCompound(page)) {
2780 index = round_up(index, HPAGE_PMD_NR);
2781 /* Beware 32-bit wraparound */
2787 * Inform shmem_writepage() how far we have reached.
2788 * No need for lock or barrier: we have the page lock.
2790 if (!PageUptodate(page))
2791 shmem_falloc.nr_falloced += index - shmem_falloc.next;
2792 shmem_falloc.next = index;
2795 * If !PageUptodate, leave it that way so that freeable pages
2796 * can be recognized if we need to rollback on error later.
2797 * But set_page_dirty so that memory pressure will swap rather
2798 * than free the pages we are allocating (and SGP_CACHE pages
2799 * might still be clean: we now need to mark those dirty too).
2801 set_page_dirty(page);
2807 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2808 i_size_write(inode, offset + len);
2809 inode->i_ctime = current_time(inode);
2811 spin_lock(&inode->i_lock);
2812 inode->i_private = NULL;
2813 spin_unlock(&inode->i_lock);
2815 inode_unlock(inode);
2819 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2821 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2823 buf->f_type = TMPFS_MAGIC;
2824 buf->f_bsize = PAGE_SIZE;
2825 buf->f_namelen = NAME_MAX;
2826 if (sbinfo->max_blocks) {
2827 buf->f_blocks = sbinfo->max_blocks;
2829 buf->f_bfree = sbinfo->max_blocks -
2830 percpu_counter_sum(&sbinfo->used_blocks);
2832 if (sbinfo->max_inodes) {
2833 buf->f_files = sbinfo->max_inodes;
2834 buf->f_ffree = sbinfo->free_inodes;
2836 /* else leave those fields 0 like simple_statfs */
2838 buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b);
2844 * File creation. Allocate an inode, and we're done..
2847 shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
2848 struct dentry *dentry, umode_t mode, dev_t dev)
2850 struct inode *inode;
2851 int error = -ENOSPC;
2853 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2855 error = simple_acl_create(dir, inode);
2858 error = security_inode_init_security(inode, dir,
2860 shmem_initxattrs, NULL);
2861 if (error && error != -EOPNOTSUPP)
2865 dir->i_size += BOGO_DIRENT_SIZE;
2866 dir->i_ctime = dir->i_mtime = current_time(dir);
2867 d_instantiate(dentry, inode);
2868 dget(dentry); /* Extra count - pin the dentry in core */
2877 shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
2878 struct dentry *dentry, umode_t mode)
2880 struct inode *inode;
2881 int error = -ENOSPC;
2883 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2885 error = security_inode_init_security(inode, dir,
2887 shmem_initxattrs, NULL);
2888 if (error && error != -EOPNOTSUPP)
2890 error = simple_acl_create(dir, inode);
2893 d_tmpfile(dentry, inode);
2901 static int shmem_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
2902 struct dentry *dentry, umode_t mode)
2906 if ((error = shmem_mknod(&init_user_ns, dir, dentry,
2907 mode | S_IFDIR, 0)))
2913 static int shmem_create(struct user_namespace *mnt_userns, struct inode *dir,
2914 struct dentry *dentry, umode_t mode, bool excl)
2916 return shmem_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0);
2922 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2924 struct inode *inode = d_inode(old_dentry);
2928 * No ordinary (disk based) filesystem counts links as inodes;
2929 * but each new link needs a new dentry, pinning lowmem, and
2930 * tmpfs dentries cannot be pruned until they are unlinked.
2931 * But if an O_TMPFILE file is linked into the tmpfs, the
2932 * first link must skip that, to get the accounting right.
2934 if (inode->i_nlink) {
2935 ret = shmem_reserve_inode(inode->i_sb, NULL);
2940 dir->i_size += BOGO_DIRENT_SIZE;
2941 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2943 ihold(inode); /* New dentry reference */
2944 dget(dentry); /* Extra pinning count for the created dentry */
2945 d_instantiate(dentry, inode);
2950 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2952 struct inode *inode = d_inode(dentry);
2954 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2955 shmem_free_inode(inode->i_sb);
2957 dir->i_size -= BOGO_DIRENT_SIZE;
2958 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2960 dput(dentry); /* Undo the count from "create" - this does all the work */
2964 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2966 if (!simple_empty(dentry))
2969 drop_nlink(d_inode(dentry));
2971 return shmem_unlink(dir, dentry);
2974 static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
2976 bool old_is_dir = d_is_dir(old_dentry);
2977 bool new_is_dir = d_is_dir(new_dentry);
2979 if (old_dir != new_dir && old_is_dir != new_is_dir) {
2981 drop_nlink(old_dir);
2984 drop_nlink(new_dir);
2988 old_dir->i_ctime = old_dir->i_mtime =
2989 new_dir->i_ctime = new_dir->i_mtime =
2990 d_inode(old_dentry)->i_ctime =
2991 d_inode(new_dentry)->i_ctime = current_time(old_dir);
2996 static int shmem_whiteout(struct user_namespace *mnt_userns,
2997 struct inode *old_dir, struct dentry *old_dentry)
2999 struct dentry *whiteout;
3002 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3006 error = shmem_mknod(&init_user_ns, old_dir, whiteout,
3007 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3013 * Cheat and hash the whiteout while the old dentry is still in
3014 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3016 * d_lookup() will consistently find one of them at this point,
3017 * not sure which one, but that isn't even important.
3024 * The VFS layer already does all the dentry stuff for rename,
3025 * we just have to decrement the usage count for the target if
3026 * it exists so that the VFS layer correctly free's it when it
3029 static int shmem_rename2(struct user_namespace *mnt_userns,
3030 struct inode *old_dir, struct dentry *old_dentry,
3031 struct inode *new_dir, struct dentry *new_dentry,
3034 struct inode *inode = d_inode(old_dentry);
3035 int they_are_dirs = S_ISDIR(inode->i_mode);
3037 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3040 if (flags & RENAME_EXCHANGE)
3041 return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
3043 if (!simple_empty(new_dentry))
3046 if (flags & RENAME_WHITEOUT) {
3049 error = shmem_whiteout(&init_user_ns, old_dir, old_dentry);
3054 if (d_really_is_positive(new_dentry)) {
3055 (void) shmem_unlink(new_dir, new_dentry);
3056 if (they_are_dirs) {
3057 drop_nlink(d_inode(new_dentry));
3058 drop_nlink(old_dir);
3060 } else if (they_are_dirs) {
3061 drop_nlink(old_dir);
3065 old_dir->i_size -= BOGO_DIRENT_SIZE;
3066 new_dir->i_size += BOGO_DIRENT_SIZE;
3067 old_dir->i_ctime = old_dir->i_mtime =
3068 new_dir->i_ctime = new_dir->i_mtime =
3069 inode->i_ctime = current_time(old_dir);
3073 static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir,
3074 struct dentry *dentry, const char *symname)
3078 struct inode *inode;
3081 len = strlen(symname) + 1;
3082 if (len > PAGE_SIZE)
3083 return -ENAMETOOLONG;
3085 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0,
3090 error = security_inode_init_security(inode, dir, &dentry->d_name,
3091 shmem_initxattrs, NULL);
3092 if (error && error != -EOPNOTSUPP) {
3097 inode->i_size = len-1;
3098 if (len <= SHORT_SYMLINK_LEN) {
3099 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3100 if (!inode->i_link) {
3104 inode->i_op = &shmem_short_symlink_operations;
3106 inode_nohighmem(inode);
3107 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3112 inode->i_mapping->a_ops = &shmem_aops;
3113 inode->i_op = &shmem_symlink_inode_operations;
3114 memcpy(page_address(page), symname, len);
3115 SetPageUptodate(page);
3116 set_page_dirty(page);
3120 dir->i_size += BOGO_DIRENT_SIZE;
3121 dir->i_ctime = dir->i_mtime = current_time(dir);
3122 d_instantiate(dentry, inode);
3127 static void shmem_put_link(void *arg)
3129 mark_page_accessed(arg);
3133 static const char *shmem_get_link(struct dentry *dentry,
3134 struct inode *inode,
3135 struct delayed_call *done)
3137 struct page *page = NULL;
3140 page = find_get_page(inode->i_mapping, 0);
3142 return ERR_PTR(-ECHILD);
3143 if (PageHWPoison(page) ||
3144 !PageUptodate(page)) {
3146 return ERR_PTR(-ECHILD);
3149 error = shmem_getpage(inode, 0, &page, SGP_READ);
3151 return ERR_PTR(error);
3153 return ERR_PTR(-ECHILD);
3154 if (PageHWPoison(page)) {
3157 return ERR_PTR(-ECHILD);
3161 set_delayed_call(done, shmem_put_link, page);
3162 return page_address(page);
3165 #ifdef CONFIG_TMPFS_XATTR
3167 * Superblocks without xattr inode operations may get some security.* xattr
3168 * support from the LSM "for free". As soon as we have any other xattrs
3169 * like ACLs, we also need to implement the security.* handlers at
3170 * filesystem level, though.
3174 * Callback for security_inode_init_security() for acquiring xattrs.
3176 static int shmem_initxattrs(struct inode *inode,
3177 const struct xattr *xattr_array,
3180 struct shmem_inode_info *info = SHMEM_I(inode);
3181 const struct xattr *xattr;
3182 struct simple_xattr *new_xattr;
3185 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3186 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3190 len = strlen(xattr->name) + 1;
3191 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3193 if (!new_xattr->name) {
3198 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3199 XATTR_SECURITY_PREFIX_LEN);
3200 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3203 simple_xattr_list_add(&info->xattrs, new_xattr);
3209 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3210 struct dentry *unused, struct inode *inode,
3211 const char *name, void *buffer, size_t size)
3213 struct shmem_inode_info *info = SHMEM_I(inode);
3215 name = xattr_full_name(handler, name);
3216 return simple_xattr_get(&info->xattrs, name, buffer, size);
3219 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3220 struct user_namespace *mnt_userns,
3221 struct dentry *unused, struct inode *inode,
3222 const char *name, const void *value,
3223 size_t size, int flags)
3225 struct shmem_inode_info *info = SHMEM_I(inode);
3227 name = xattr_full_name(handler, name);
3228 return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
3231 static const struct xattr_handler shmem_security_xattr_handler = {
3232 .prefix = XATTR_SECURITY_PREFIX,
3233 .get = shmem_xattr_handler_get,
3234 .set = shmem_xattr_handler_set,
3237 static const struct xattr_handler shmem_trusted_xattr_handler = {
3238 .prefix = XATTR_TRUSTED_PREFIX,
3239 .get = shmem_xattr_handler_get,
3240 .set = shmem_xattr_handler_set,
3243 static const struct xattr_handler *shmem_xattr_handlers[] = {
3244 #ifdef CONFIG_TMPFS_POSIX_ACL
3245 &posix_acl_access_xattr_handler,
3246 &posix_acl_default_xattr_handler,
3248 &shmem_security_xattr_handler,
3249 &shmem_trusted_xattr_handler,
3253 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3255 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3256 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3258 #endif /* CONFIG_TMPFS_XATTR */
3260 static const struct inode_operations shmem_short_symlink_operations = {
3261 .get_link = simple_get_link,
3262 #ifdef CONFIG_TMPFS_XATTR
3263 .listxattr = shmem_listxattr,
3267 static const struct inode_operations shmem_symlink_inode_operations = {
3268 .get_link = shmem_get_link,
3269 #ifdef CONFIG_TMPFS_XATTR
3270 .listxattr = shmem_listxattr,
3274 static struct dentry *shmem_get_parent(struct dentry *child)
3276 return ERR_PTR(-ESTALE);
3279 static int shmem_match(struct inode *ino, void *vfh)
3283 inum = (inum << 32) | fh[1];
3284 return ino->i_ino == inum && fh[0] == ino->i_generation;
3287 /* Find any alias of inode, but prefer a hashed alias */
3288 static struct dentry *shmem_find_alias(struct inode *inode)
3290 struct dentry *alias = d_find_alias(inode);
3292 return alias ?: d_find_any_alias(inode);
3296 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3297 struct fid *fid, int fh_len, int fh_type)
3299 struct inode *inode;
3300 struct dentry *dentry = NULL;
3307 inum = (inum << 32) | fid->raw[1];
3309 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3310 shmem_match, fid->raw);
3312 dentry = shmem_find_alias(inode);
3319 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3320 struct inode *parent)
3324 return FILEID_INVALID;
3327 if (inode_unhashed(inode)) {
3328 /* Unfortunately insert_inode_hash is not idempotent,
3329 * so as we hash inodes here rather than at creation
3330 * time, we need a lock to ensure we only try
3333 static DEFINE_SPINLOCK(lock);
3335 if (inode_unhashed(inode))
3336 __insert_inode_hash(inode,
3337 inode->i_ino + inode->i_generation);
3341 fh[0] = inode->i_generation;
3342 fh[1] = inode->i_ino;
3343 fh[2] = ((__u64)inode->i_ino) >> 32;
3349 static const struct export_operations shmem_export_ops = {
3350 .get_parent = shmem_get_parent,
3351 .encode_fh = shmem_encode_fh,
3352 .fh_to_dentry = shmem_fh_to_dentry,
3368 static const struct constant_table shmem_param_enums_huge[] = {
3369 {"never", SHMEM_HUGE_NEVER },
3370 {"always", SHMEM_HUGE_ALWAYS },
3371 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3372 {"advise", SHMEM_HUGE_ADVISE },
3376 const struct fs_parameter_spec shmem_fs_parameters[] = {
3377 fsparam_u32 ("gid", Opt_gid),
3378 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3379 fsparam_u32oct("mode", Opt_mode),
3380 fsparam_string("mpol", Opt_mpol),
3381 fsparam_string("nr_blocks", Opt_nr_blocks),
3382 fsparam_string("nr_inodes", Opt_nr_inodes),
3383 fsparam_string("size", Opt_size),
3384 fsparam_u32 ("uid", Opt_uid),
3385 fsparam_flag ("inode32", Opt_inode32),
3386 fsparam_flag ("inode64", Opt_inode64),
3390 static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3392 struct shmem_options *ctx = fc->fs_private;
3393 struct fs_parse_result result;
3394 unsigned long long size;
3400 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3406 size = memparse(param->string, &rest);
3408 size <<= PAGE_SHIFT;
3409 size *= totalram_pages();
3415 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3416 ctx->seen |= SHMEM_SEEN_BLOCKS;
3419 ctx->blocks = memparse(param->string, &rest);
3422 ctx->seen |= SHMEM_SEEN_BLOCKS;
3425 ctx->inodes = memparse(param->string, &rest);
3428 ctx->seen |= SHMEM_SEEN_INODES;
3431 ctx->mode = result.uint_32 & 07777;
3434 kuid = make_kuid(current_user_ns(), result.uint_32);
3435 if (!uid_valid(kuid))
3439 * The requested uid must be representable in the
3440 * filesystem's idmapping.
3442 if (!kuid_has_mapping(fc->user_ns, kuid))
3448 kgid = make_kgid(current_user_ns(), result.uint_32);
3449 if (!gid_valid(kgid))
3453 * The requested gid must be representable in the
3454 * filesystem's idmapping.
3456 if (!kgid_has_mapping(fc->user_ns, kgid))
3462 ctx->huge = result.uint_32;
3463 if (ctx->huge != SHMEM_HUGE_NEVER &&
3464 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
3465 has_transparent_hugepage()))
3466 goto unsupported_parameter;
3467 ctx->seen |= SHMEM_SEEN_HUGE;
3470 if (IS_ENABLED(CONFIG_NUMA)) {
3471 mpol_put(ctx->mpol);
3473 if (mpol_parse_str(param->string, &ctx->mpol))
3477 goto unsupported_parameter;
3479 ctx->full_inums = false;
3480 ctx->seen |= SHMEM_SEEN_INUMS;
3483 if (sizeof(ino_t) < 8) {
3485 "Cannot use inode64 with <64bit inums in kernel\n");
3487 ctx->full_inums = true;
3488 ctx->seen |= SHMEM_SEEN_INUMS;
3493 unsupported_parameter:
3494 return invalfc(fc, "Unsupported parameter '%s'", param->key);
3496 return invalfc(fc, "Bad value for '%s'", param->key);
3499 static int shmem_parse_options(struct fs_context *fc, void *data)
3501 char *options = data;
3504 int err = security_sb_eat_lsm_opts(options, &fc->security);
3509 while (options != NULL) {
3510 char *this_char = options;
3513 * NUL-terminate this option: unfortunately,
3514 * mount options form a comma-separated list,
3515 * but mpol's nodelist may also contain commas.
3517 options = strchr(options, ',');
3518 if (options == NULL)
3521 if (!isdigit(*options)) {
3527 char *value = strchr(this_char, '=');
3533 len = strlen(value);
3535 err = vfs_parse_fs_string(fc, this_char, value, len);
3544 * Reconfigure a shmem filesystem.
3546 * Note that we disallow change from limited->unlimited blocks/inodes while any
3547 * are in use; but we must separately disallow unlimited->limited, because in
3548 * that case we have no record of how much is already in use.
3550 static int shmem_reconfigure(struct fs_context *fc)
3552 struct shmem_options *ctx = fc->fs_private;
3553 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
3554 unsigned long inodes;
3555 struct mempolicy *mpol = NULL;
3558 raw_spin_lock(&sbinfo->stat_lock);
3559 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3560 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
3561 if (!sbinfo->max_blocks) {
3562 err = "Cannot retroactively limit size";
3565 if (percpu_counter_compare(&sbinfo->used_blocks,
3567 err = "Too small a size for current use";
3571 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
3572 if (!sbinfo->max_inodes) {
3573 err = "Cannot retroactively limit inodes";
3576 if (ctx->inodes < inodes) {
3577 err = "Too few inodes for current use";
3582 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
3583 sbinfo->next_ino > UINT_MAX) {
3584 err = "Current inum too high to switch to 32-bit inums";
3588 if (ctx->seen & SHMEM_SEEN_HUGE)
3589 sbinfo->huge = ctx->huge;
3590 if (ctx->seen & SHMEM_SEEN_INUMS)
3591 sbinfo->full_inums = ctx->full_inums;
3592 if (ctx->seen & SHMEM_SEEN_BLOCKS)
3593 sbinfo->max_blocks = ctx->blocks;
3594 if (ctx->seen & SHMEM_SEEN_INODES) {
3595 sbinfo->max_inodes = ctx->inodes;
3596 sbinfo->free_inodes = ctx->inodes - inodes;
3600 * Preserve previous mempolicy unless mpol remount option was specified.
3603 mpol = sbinfo->mpol;
3604 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
3607 raw_spin_unlock(&sbinfo->stat_lock);
3611 raw_spin_unlock(&sbinfo->stat_lock);
3612 return invalfc(fc, "%s", err);
3615 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3617 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3619 if (sbinfo->max_blocks != shmem_default_max_blocks())
3620 seq_printf(seq, ",size=%luk",
3621 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3622 if (sbinfo->max_inodes != shmem_default_max_inodes())
3623 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3624 if (sbinfo->mode != (0777 | S_ISVTX))
3625 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3626 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3627 seq_printf(seq, ",uid=%u",
3628 from_kuid_munged(&init_user_ns, sbinfo->uid));
3629 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3630 seq_printf(seq, ",gid=%u",
3631 from_kgid_munged(&init_user_ns, sbinfo->gid));
3634 * Showing inode{64,32} might be useful even if it's the system default,
3635 * since then people don't have to resort to checking both here and
3636 * /proc/config.gz to confirm 64-bit inums were successfully applied
3637 * (which may not even exist if IKCONFIG_PROC isn't enabled).
3639 * We hide it when inode64 isn't the default and we are using 32-bit
3640 * inodes, since that probably just means the feature isn't even under
3645 * +-----------------+-----------------+
3646 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
3647 * +------------------+-----------------+-----------------+
3648 * | full_inums=true | show | show |
3649 * | full_inums=false | show | hide |
3650 * +------------------+-----------------+-----------------+
3653 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
3654 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
3655 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3656 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3658 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3660 shmem_show_mpol(seq, sbinfo->mpol);
3664 #endif /* CONFIG_TMPFS */
3666 static void shmem_put_super(struct super_block *sb)
3668 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3670 free_percpu(sbinfo->ino_batch);
3671 percpu_counter_destroy(&sbinfo->used_blocks);
3672 mpol_put(sbinfo->mpol);
3674 sb->s_fs_info = NULL;
3677 static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
3679 struct shmem_options *ctx = fc->fs_private;
3680 struct inode *inode;
3681 struct shmem_sb_info *sbinfo;
3683 /* Round up to L1_CACHE_BYTES to resist false sharing */
3684 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3685 L1_CACHE_BYTES), GFP_KERNEL);
3689 sb->s_fs_info = sbinfo;
3693 * Per default we only allow half of the physical ram per
3694 * tmpfs instance, limiting inodes to one per page of lowmem;
3695 * but the internal instance is left unlimited.
3697 if (!(sb->s_flags & SB_KERNMOUNT)) {
3698 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
3699 ctx->blocks = shmem_default_max_blocks();
3700 if (!(ctx->seen & SHMEM_SEEN_INODES))
3701 ctx->inodes = shmem_default_max_inodes();
3702 if (!(ctx->seen & SHMEM_SEEN_INUMS))
3703 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
3705 sb->s_flags |= SB_NOUSER;
3707 sb->s_export_op = &shmem_export_ops;
3708 sb->s_flags |= SB_NOSEC;
3710 sb->s_flags |= SB_NOUSER;
3712 sbinfo->max_blocks = ctx->blocks;
3713 sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
3714 if (sb->s_flags & SB_KERNMOUNT) {
3715 sbinfo->ino_batch = alloc_percpu(ino_t);
3716 if (!sbinfo->ino_batch)
3719 sbinfo->uid = ctx->uid;
3720 sbinfo->gid = ctx->gid;
3721 sbinfo->full_inums = ctx->full_inums;
3722 sbinfo->mode = ctx->mode;
3723 sbinfo->huge = ctx->huge;
3724 sbinfo->mpol = ctx->mpol;
3727 raw_spin_lock_init(&sbinfo->stat_lock);
3728 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3730 spin_lock_init(&sbinfo->shrinklist_lock);
3731 INIT_LIST_HEAD(&sbinfo->shrinklist);
3733 sb->s_maxbytes = MAX_LFS_FILESIZE;
3734 sb->s_blocksize = PAGE_SIZE;
3735 sb->s_blocksize_bits = PAGE_SHIFT;
3736 sb->s_magic = TMPFS_MAGIC;
3737 sb->s_op = &shmem_ops;
3738 sb->s_time_gran = 1;
3739 #ifdef CONFIG_TMPFS_XATTR
3740 sb->s_xattr = shmem_xattr_handlers;
3742 #ifdef CONFIG_TMPFS_POSIX_ACL
3743 sb->s_flags |= SB_POSIXACL;
3745 uuid_gen(&sb->s_uuid);
3747 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3750 inode->i_uid = sbinfo->uid;
3751 inode->i_gid = sbinfo->gid;
3752 sb->s_root = d_make_root(inode);
3758 shmem_put_super(sb);
3762 static int shmem_get_tree(struct fs_context *fc)
3764 return get_tree_nodev(fc, shmem_fill_super);
3767 static void shmem_free_fc(struct fs_context *fc)
3769 struct shmem_options *ctx = fc->fs_private;
3772 mpol_put(ctx->mpol);
3777 static const struct fs_context_operations shmem_fs_context_ops = {
3778 .free = shmem_free_fc,
3779 .get_tree = shmem_get_tree,
3781 .parse_monolithic = shmem_parse_options,
3782 .parse_param = shmem_parse_one,
3783 .reconfigure = shmem_reconfigure,
3787 static struct kmem_cache *shmem_inode_cachep;
3789 static struct inode *shmem_alloc_inode(struct super_block *sb)
3791 struct shmem_inode_info *info;
3792 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3795 return &info->vfs_inode;
3798 static void shmem_free_in_core_inode(struct inode *inode)
3800 if (S_ISLNK(inode->i_mode))
3801 kfree(inode->i_link);
3802 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3805 static void shmem_destroy_inode(struct inode *inode)
3807 if (S_ISREG(inode->i_mode))
3808 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3811 static void shmem_init_inode(void *foo)
3813 struct shmem_inode_info *info = foo;
3814 inode_init_once(&info->vfs_inode);
3817 static void shmem_init_inodecache(void)
3819 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3820 sizeof(struct shmem_inode_info),
3821 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3824 static void shmem_destroy_inodecache(void)
3826 kmem_cache_destroy(shmem_inode_cachep);
3829 /* Keep the page in page cache instead of truncating it */
3830 static int shmem_error_remove_page(struct address_space *mapping,
3836 const struct address_space_operations shmem_aops = {
3837 .writepage = shmem_writepage,
3838 .set_page_dirty = __set_page_dirty_no_writeback,
3840 .write_begin = shmem_write_begin,
3841 .write_end = shmem_write_end,
3843 #ifdef CONFIG_MIGRATION
3844 .migratepage = migrate_page,
3846 .error_remove_page = shmem_error_remove_page,
3848 EXPORT_SYMBOL(shmem_aops);
3850 static const struct file_operations shmem_file_operations = {
3852 .get_unmapped_area = shmem_get_unmapped_area,
3854 .llseek = shmem_file_llseek,
3855 .read_iter = shmem_file_read_iter,
3856 .write_iter = generic_file_write_iter,
3857 .fsync = noop_fsync,
3858 .splice_read = generic_file_splice_read,
3859 .splice_write = iter_file_splice_write,
3860 .fallocate = shmem_fallocate,
3864 static const struct inode_operations shmem_inode_operations = {
3865 .getattr = shmem_getattr,
3866 .setattr = shmem_setattr,
3867 #ifdef CONFIG_TMPFS_XATTR
3868 .listxattr = shmem_listxattr,
3869 .set_acl = simple_set_acl,
3873 static const struct inode_operations shmem_dir_inode_operations = {
3875 .create = shmem_create,
3876 .lookup = simple_lookup,
3878 .unlink = shmem_unlink,
3879 .symlink = shmem_symlink,
3880 .mkdir = shmem_mkdir,
3881 .rmdir = shmem_rmdir,
3882 .mknod = shmem_mknod,
3883 .rename = shmem_rename2,
3884 .tmpfile = shmem_tmpfile,
3886 #ifdef CONFIG_TMPFS_XATTR
3887 .listxattr = shmem_listxattr,
3889 #ifdef CONFIG_TMPFS_POSIX_ACL
3890 .setattr = shmem_setattr,
3891 .set_acl = simple_set_acl,
3895 static const struct inode_operations shmem_special_inode_operations = {
3896 #ifdef CONFIG_TMPFS_XATTR
3897 .listxattr = shmem_listxattr,
3899 #ifdef CONFIG_TMPFS_POSIX_ACL
3900 .setattr = shmem_setattr,
3901 .set_acl = simple_set_acl,
3905 static const struct super_operations shmem_ops = {
3906 .alloc_inode = shmem_alloc_inode,
3907 .free_inode = shmem_free_in_core_inode,
3908 .destroy_inode = shmem_destroy_inode,
3910 .statfs = shmem_statfs,
3911 .show_options = shmem_show_options,
3913 .evict_inode = shmem_evict_inode,
3914 .drop_inode = generic_delete_inode,
3915 .put_super = shmem_put_super,
3916 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3917 .nr_cached_objects = shmem_unused_huge_count,
3918 .free_cached_objects = shmem_unused_huge_scan,
3922 static const struct vm_operations_struct shmem_vm_ops = {
3923 .fault = shmem_fault,
3924 .map_pages = filemap_map_pages,
3926 .set_policy = shmem_set_policy,
3927 .get_policy = shmem_get_policy,
3931 int shmem_init_fs_context(struct fs_context *fc)
3933 struct shmem_options *ctx;
3935 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
3939 ctx->mode = 0777 | S_ISVTX;
3940 ctx->uid = current_fsuid();
3941 ctx->gid = current_fsgid();
3943 fc->fs_private = ctx;
3944 fc->ops = &shmem_fs_context_ops;
3948 static struct file_system_type shmem_fs_type = {
3949 .owner = THIS_MODULE,
3951 .init_fs_context = shmem_init_fs_context,
3953 .parameters = shmem_fs_parameters,
3955 .kill_sb = kill_litter_super,
3956 .fs_flags = FS_USERNS_MOUNT | FS_THP_SUPPORT,
3959 int __init shmem_init(void)
3963 shmem_init_inodecache();
3965 error = register_filesystem(&shmem_fs_type);
3967 pr_err("Could not register tmpfs\n");
3971 shm_mnt = kern_mount(&shmem_fs_type);
3972 if (IS_ERR(shm_mnt)) {
3973 error = PTR_ERR(shm_mnt);
3974 pr_err("Could not kern_mount tmpfs\n");
3978 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3979 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
3980 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3982 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
3987 unregister_filesystem(&shmem_fs_type);
3989 shmem_destroy_inodecache();
3990 shm_mnt = ERR_PTR(error);
3994 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
3995 static ssize_t shmem_enabled_show(struct kobject *kobj,
3996 struct kobj_attribute *attr, char *buf)
3998 static const int values[] = {
4000 SHMEM_HUGE_WITHIN_SIZE,
4009 for (i = 0; i < ARRAY_SIZE(values); i++) {
4010 len += sysfs_emit_at(buf, len,
4011 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
4013 shmem_format_huge(values[i]));
4016 len += sysfs_emit_at(buf, len, "\n");
4021 static ssize_t shmem_enabled_store(struct kobject *kobj,
4022 struct kobj_attribute *attr, const char *buf, size_t count)
4027 if (count + 1 > sizeof(tmp))
4029 memcpy(tmp, buf, count);
4031 if (count && tmp[count - 1] == '\n')
4032 tmp[count - 1] = '\0';
4034 huge = shmem_parse_huge(tmp);
4035 if (huge == -EINVAL)
4037 if (!has_transparent_hugepage() &&
4038 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4042 if (shmem_huge > SHMEM_HUGE_DENY)
4043 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4047 struct kobj_attribute shmem_enabled_attr =
4048 __ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
4049 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4051 #else /* !CONFIG_SHMEM */
4054 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4056 * This is intended for small system where the benefits of the full
4057 * shmem code (swap-backed and resource-limited) are outweighed by
4058 * their complexity. On systems without swap this code should be
4059 * effectively equivalent, but much lighter weight.
4062 static struct file_system_type shmem_fs_type = {
4064 .init_fs_context = ramfs_init_fs_context,
4065 .parameters = ramfs_fs_parameters,
4066 .kill_sb = ramfs_kill_sb,
4067 .fs_flags = FS_USERNS_MOUNT,
4070 int __init shmem_init(void)
4072 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4074 shm_mnt = kern_mount(&shmem_fs_type);
4075 BUG_ON(IS_ERR(shm_mnt));
4080 int shmem_unuse(unsigned int type, bool frontswap,
4081 unsigned long *fs_pages_to_unuse)
4086 int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
4091 void shmem_unlock_mapping(struct address_space *mapping)
4096 unsigned long shmem_get_unmapped_area(struct file *file,
4097 unsigned long addr, unsigned long len,
4098 unsigned long pgoff, unsigned long flags)
4100 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4104 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4106 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4108 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4110 #define shmem_vm_ops generic_file_vm_ops
4111 #define shmem_file_operations ramfs_file_operations
4112 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4113 #define shmem_acct_size(flags, size) 0
4114 #define shmem_unacct_size(flags, size) do {} while (0)
4116 #endif /* CONFIG_SHMEM */
4120 static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4121 unsigned long flags, unsigned int i_flags)
4123 struct inode *inode;
4127 return ERR_CAST(mnt);
4129 if (size < 0 || size > MAX_LFS_FILESIZE)
4130 return ERR_PTR(-EINVAL);
4132 if (shmem_acct_size(flags, size))
4133 return ERR_PTR(-ENOMEM);
4135 inode = shmem_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0,
4137 if (unlikely(!inode)) {
4138 shmem_unacct_size(flags, size);
4139 return ERR_PTR(-ENOSPC);
4141 inode->i_flags |= i_flags;
4142 inode->i_size = size;
4143 clear_nlink(inode); /* It is unlinked */
4144 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4146 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4147 &shmem_file_operations);
4154 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4155 * kernel internal. There will be NO LSM permission checks against the
4156 * underlying inode. So users of this interface must do LSM checks at a
4157 * higher layer. The users are the big_key and shm implementations. LSM
4158 * checks are provided at the key or shm level rather than the inode.
4159 * @name: name for dentry (to be seen in /proc/<pid>/maps
4160 * @size: size to be set for the file
4161 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4163 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4165 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4169 * shmem_file_setup - get an unlinked file living in tmpfs
4170 * @name: name for dentry (to be seen in /proc/<pid>/maps
4171 * @size: size to be set for the file
4172 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4174 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4176 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4178 EXPORT_SYMBOL_GPL(shmem_file_setup);
4181 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4182 * @mnt: the tmpfs mount where the file will be created
4183 * @name: name for dentry (to be seen in /proc/<pid>/maps
4184 * @size: size to be set for the file
4185 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4187 struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4188 loff_t size, unsigned long flags)
4190 return __shmem_file_setup(mnt, name, size, flags, 0);
4192 EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4195 * shmem_zero_setup - setup a shared anonymous mapping
4196 * @vma: the vma to be mmapped is prepared by do_mmap
4198 int shmem_zero_setup(struct vm_area_struct *vma)
4201 loff_t size = vma->vm_end - vma->vm_start;
4204 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4205 * between XFS directory reading and selinux: since this file is only
4206 * accessible to the user through its mapping, use S_PRIVATE flag to
4207 * bypass file security, in the same way as shmem_kernel_file_setup().
4209 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4211 return PTR_ERR(file);
4215 vma->vm_file = file;
4216 vma->vm_ops = &shmem_vm_ops;
4218 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
4219 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4220 (vma->vm_end & HPAGE_PMD_MASK)) {
4221 khugepaged_enter(vma, vma->vm_flags);
4228 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4229 * @mapping: the page's address_space
4230 * @index: the page index
4231 * @gfp: the page allocator flags to use if allocating
4233 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4234 * with any new page allocations done using the specified allocation flags.
4235 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4236 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4237 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4239 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4240 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4242 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4243 pgoff_t index, gfp_t gfp)
4246 struct inode *inode = mapping->host;
4250 BUG_ON(!shmem_mapping(mapping));
4251 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4252 gfp, NULL, NULL, NULL);
4254 return ERR_PTR(error);
4257 if (PageHWPoison(page)) {
4259 return ERR_PTR(-EIO);
4265 * The tiny !SHMEM case uses ramfs without swap
4267 return read_cache_page_gfp(mapping, index, gfp);
4270 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);