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>
42 #include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */
44 static struct vfsmount *shm_mnt;
48 * This virtual memory filesystem is heavily based on the ramfs. It
49 * extends ramfs by the ability to use swap and honor resource limits
50 * which makes it a completely usable filesystem.
53 #include <linux/xattr.h>
54 #include <linux/exportfs.h>
55 #include <linux/posix_acl.h>
56 #include <linux/posix_acl_xattr.h>
57 #include <linux/mman.h>
58 #include <linux/string.h>
59 #include <linux/slab.h>
60 #include <linux/backing-dev.h>
61 #include <linux/shmem_fs.h>
62 #include <linux/writeback.h>
63 #include <linux/blkdev.h>
64 #include <linux/pagevec.h>
65 #include <linux/percpu_counter.h>
66 #include <linux/falloc.h>
67 #include <linux/splice.h>
68 #include <linux/security.h>
69 #include <linux/swapops.h>
70 #include <linux/mempolicy.h>
71 #include <linux/namei.h>
72 #include <linux/ctype.h>
73 #include <linux/migrate.h>
74 #include <linux/highmem.h>
75 #include <linux/seq_file.h>
76 #include <linux/magic.h>
77 #include <linux/syscalls.h>
78 #include <linux/fcntl.h>
79 #include <uapi/linux/memfd.h>
80 #include <linux/userfaultfd_k.h>
81 #include <linux/rmap.h>
82 #include <linux/uuid.h>
84 #include <linux/uaccess.h>
88 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
89 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
91 /* Pretend that each entry is of this size in directory's i_size */
92 #define BOGO_DIRENT_SIZE 20
94 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
95 #define SHORT_SYMLINK_LEN 128
98 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
99 * inode->i_private (with i_mutex making sure that it has only one user at
100 * a time): we would prefer not to enlarge the shmem inode just for that.
102 struct shmem_falloc {
103 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
104 pgoff_t start; /* start of range currently being fallocated */
105 pgoff_t next; /* the next page offset to be fallocated */
106 pgoff_t nr_falloced; /* how many new pages have been fallocated */
107 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
110 struct shmem_options {
111 unsigned long long blocks;
112 unsigned long long inodes;
113 struct mempolicy *mpol;
120 #define SHMEM_SEEN_BLOCKS 1
121 #define SHMEM_SEEN_INODES 2
122 #define SHMEM_SEEN_HUGE 4
123 #define SHMEM_SEEN_INUMS 8
127 static unsigned long shmem_default_max_blocks(void)
129 return totalram_pages() / 2;
132 static unsigned long shmem_default_max_inodes(void)
134 unsigned long nr_pages = totalram_pages();
136 return min(nr_pages - totalhigh_pages(), nr_pages / 2);
140 static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
141 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
142 struct shmem_inode_info *info, pgoff_t index);
143 static int shmem_swapin_page(struct inode *inode, pgoff_t index,
144 struct page **pagep, enum sgp_type sgp,
145 gfp_t gfp, struct vm_area_struct *vma,
146 vm_fault_t *fault_type);
147 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
148 struct page **pagep, enum sgp_type sgp,
149 gfp_t gfp, struct vm_area_struct *vma,
150 struct vm_fault *vmf, vm_fault_t *fault_type);
152 int shmem_getpage(struct inode *inode, pgoff_t index,
153 struct page **pagep, enum sgp_type sgp)
155 return shmem_getpage_gfp(inode, index, pagep, sgp,
156 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
159 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
161 return sb->s_fs_info;
165 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
166 * for shared memory and for shared anonymous (/dev/zero) mappings
167 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
168 * consistent with the pre-accounting of private mappings ...
170 static inline int shmem_acct_size(unsigned long flags, loff_t size)
172 return (flags & VM_NORESERVE) ?
173 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
176 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
178 if (!(flags & VM_NORESERVE))
179 vm_unacct_memory(VM_ACCT(size));
182 static inline int shmem_reacct_size(unsigned long flags,
183 loff_t oldsize, loff_t newsize)
185 if (!(flags & VM_NORESERVE)) {
186 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
187 return security_vm_enough_memory_mm(current->mm,
188 VM_ACCT(newsize) - VM_ACCT(oldsize));
189 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
190 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
196 * ... whereas tmpfs objects are accounted incrementally as
197 * pages are allocated, in order to allow large sparse files.
198 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
199 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
201 static inline int shmem_acct_block(unsigned long flags, long pages)
203 if (!(flags & VM_NORESERVE))
206 return security_vm_enough_memory_mm(current->mm,
207 pages * VM_ACCT(PAGE_SIZE));
210 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
212 if (flags & VM_NORESERVE)
213 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
216 static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
218 struct shmem_inode_info *info = SHMEM_I(inode);
219 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
221 if (shmem_acct_block(info->flags, pages))
224 if (sbinfo->max_blocks) {
225 if (percpu_counter_compare(&sbinfo->used_blocks,
226 sbinfo->max_blocks - pages) > 0)
228 percpu_counter_add(&sbinfo->used_blocks, pages);
234 shmem_unacct_blocks(info->flags, pages);
238 static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
240 struct shmem_inode_info *info = SHMEM_I(inode);
241 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
243 if (sbinfo->max_blocks)
244 percpu_counter_sub(&sbinfo->used_blocks, pages);
245 shmem_unacct_blocks(info->flags, pages);
248 static const struct super_operations shmem_ops;
249 const struct address_space_operations shmem_aops;
250 static const struct file_operations shmem_file_operations;
251 static const struct inode_operations shmem_inode_operations;
252 static const struct inode_operations shmem_dir_inode_operations;
253 static const struct inode_operations shmem_special_inode_operations;
254 static const struct vm_operations_struct shmem_vm_ops;
255 static struct file_system_type shmem_fs_type;
257 bool vma_is_shmem(struct vm_area_struct *vma)
259 return vma->vm_ops == &shmem_vm_ops;
262 static LIST_HEAD(shmem_swaplist);
263 static DEFINE_MUTEX(shmem_swaplist_mutex);
266 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
267 * produces a novel ino for the newly allocated inode.
269 * It may also be called when making a hard link to permit the space needed by
270 * each dentry. However, in that case, no new inode number is needed since that
271 * internally draws from another pool of inode numbers (currently global
272 * get_next_ino()). This case is indicated by passing NULL as inop.
274 #define SHMEM_INO_BATCH 1024
275 static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
277 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
280 if (!(sb->s_flags & SB_KERNMOUNT)) {
281 spin_lock(&sbinfo->stat_lock);
282 if (sbinfo->max_inodes) {
283 if (!sbinfo->free_inodes) {
284 spin_unlock(&sbinfo->stat_lock);
287 sbinfo->free_inodes--;
290 ino = sbinfo->next_ino++;
291 if (unlikely(is_zero_ino(ino)))
292 ino = sbinfo->next_ino++;
293 if (unlikely(!sbinfo->full_inums &&
296 * Emulate get_next_ino uint wraparound for
299 if (IS_ENABLED(CONFIG_64BIT))
300 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
301 __func__, MINOR(sb->s_dev));
302 sbinfo->next_ino = 1;
303 ino = sbinfo->next_ino++;
307 spin_unlock(&sbinfo->stat_lock);
310 * __shmem_file_setup, one of our callers, is lock-free: it
311 * doesn't hold stat_lock in shmem_reserve_inode since
312 * max_inodes is always 0, and is called from potentially
313 * unknown contexts. As such, use a per-cpu batched allocator
314 * which doesn't require the per-sb stat_lock unless we are at
315 * the batch boundary.
317 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
318 * shmem mounts are not exposed to userspace, so we don't need
319 * to worry about things like glibc compatibility.
322 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
324 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
325 spin_lock(&sbinfo->stat_lock);
326 ino = sbinfo->next_ino;
327 sbinfo->next_ino += SHMEM_INO_BATCH;
328 spin_unlock(&sbinfo->stat_lock);
329 if (unlikely(is_zero_ino(ino)))
340 static void shmem_free_inode(struct super_block *sb)
342 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
343 if (sbinfo->max_inodes) {
344 spin_lock(&sbinfo->stat_lock);
345 sbinfo->free_inodes++;
346 spin_unlock(&sbinfo->stat_lock);
351 * shmem_recalc_inode - recalculate the block usage of an inode
352 * @inode: inode to recalc
354 * We have to calculate the free blocks since the mm can drop
355 * undirtied hole pages behind our back.
357 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
358 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
360 * It has to be called with the spinlock held.
362 static void shmem_recalc_inode(struct inode *inode)
364 struct shmem_inode_info *info = SHMEM_I(inode);
367 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
369 info->alloced -= freed;
370 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
371 shmem_inode_unacct_blocks(inode, freed);
375 bool shmem_charge(struct inode *inode, long pages)
377 struct shmem_inode_info *info = SHMEM_I(inode);
380 if (!shmem_inode_acct_block(inode, pages))
383 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
384 inode->i_mapping->nrpages += pages;
386 spin_lock_irqsave(&info->lock, flags);
387 info->alloced += pages;
388 inode->i_blocks += pages * BLOCKS_PER_PAGE;
389 shmem_recalc_inode(inode);
390 spin_unlock_irqrestore(&info->lock, flags);
395 void shmem_uncharge(struct inode *inode, long pages)
397 struct shmem_inode_info *info = SHMEM_I(inode);
400 /* nrpages adjustment done by __delete_from_page_cache() or caller */
402 spin_lock_irqsave(&info->lock, flags);
403 info->alloced -= pages;
404 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
405 shmem_recalc_inode(inode);
406 spin_unlock_irqrestore(&info->lock, flags);
408 shmem_inode_unacct_blocks(inode, pages);
412 * Replace item expected in xarray by a new item, while holding xa_lock.
414 static int shmem_replace_entry(struct address_space *mapping,
415 pgoff_t index, void *expected, void *replacement)
417 XA_STATE(xas, &mapping->i_pages, index);
420 VM_BUG_ON(!expected);
421 VM_BUG_ON(!replacement);
422 item = xas_load(&xas);
423 if (item != expected)
425 xas_store(&xas, replacement);
430 * Sometimes, before we decide whether to proceed or to fail, we must check
431 * that an entry was not already brought back from swap by a racing thread.
433 * Checking page is not enough: by the time a SwapCache page is locked, it
434 * might be reused, and again be SwapCache, using the same swap as before.
436 static bool shmem_confirm_swap(struct address_space *mapping,
437 pgoff_t index, swp_entry_t swap)
439 return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap);
443 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
446 * disables huge pages for the mount;
448 * enables huge pages for the mount;
449 * SHMEM_HUGE_WITHIN_SIZE:
450 * only allocate huge pages if the page will be fully within i_size,
451 * also respect fadvise()/madvise() hints;
453 * only allocate huge pages if requested with fadvise()/madvise();
456 #define SHMEM_HUGE_NEVER 0
457 #define SHMEM_HUGE_ALWAYS 1
458 #define SHMEM_HUGE_WITHIN_SIZE 2
459 #define SHMEM_HUGE_ADVISE 3
463 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
466 * disables huge on shm_mnt and all mounts, for emergency use;
468 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
471 #define SHMEM_HUGE_DENY (-1)
472 #define SHMEM_HUGE_FORCE (-2)
474 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
475 /* ifdef here to avoid bloating shmem.o when not necessary */
477 static int shmem_huge __read_mostly;
479 #if defined(CONFIG_SYSFS)
480 static int shmem_parse_huge(const char *str)
482 if (!strcmp(str, "never"))
483 return SHMEM_HUGE_NEVER;
484 if (!strcmp(str, "always"))
485 return SHMEM_HUGE_ALWAYS;
486 if (!strcmp(str, "within_size"))
487 return SHMEM_HUGE_WITHIN_SIZE;
488 if (!strcmp(str, "advise"))
489 return SHMEM_HUGE_ADVISE;
490 if (!strcmp(str, "deny"))
491 return SHMEM_HUGE_DENY;
492 if (!strcmp(str, "force"))
493 return SHMEM_HUGE_FORCE;
498 #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
499 static const char *shmem_format_huge(int huge)
502 case SHMEM_HUGE_NEVER:
504 case SHMEM_HUGE_ALWAYS:
506 case SHMEM_HUGE_WITHIN_SIZE:
507 return "within_size";
508 case SHMEM_HUGE_ADVISE:
510 case SHMEM_HUGE_DENY:
512 case SHMEM_HUGE_FORCE:
521 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
522 struct shrink_control *sc, unsigned long nr_to_split)
524 LIST_HEAD(list), *pos, *next;
525 LIST_HEAD(to_remove);
527 struct shmem_inode_info *info;
529 unsigned long batch = sc ? sc->nr_to_scan : 128;
530 int removed = 0, split = 0;
532 if (list_empty(&sbinfo->shrinklist))
535 spin_lock(&sbinfo->shrinklist_lock);
536 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
537 info = list_entry(pos, struct shmem_inode_info, shrinklist);
540 inode = igrab(&info->vfs_inode);
542 /* inode is about to be evicted */
544 list_del_init(&info->shrinklist);
549 /* Check if there's anything to gain */
550 if (round_up(inode->i_size, PAGE_SIZE) ==
551 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
552 list_move(&info->shrinklist, &to_remove);
557 list_move(&info->shrinklist, &list);
562 spin_unlock(&sbinfo->shrinklist_lock);
564 list_for_each_safe(pos, next, &to_remove) {
565 info = list_entry(pos, struct shmem_inode_info, shrinklist);
566 inode = &info->vfs_inode;
567 list_del_init(&info->shrinklist);
571 list_for_each_safe(pos, next, &list) {
574 info = list_entry(pos, struct shmem_inode_info, shrinklist);
575 inode = &info->vfs_inode;
577 if (nr_to_split && split >= nr_to_split)
580 page = find_get_page(inode->i_mapping,
581 (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
585 /* No huge page at the end of the file: nothing to split */
586 if (!PageTransHuge(page)) {
592 * Leave the inode on the list if we failed to lock
593 * the page at this time.
595 * Waiting for the lock may lead to deadlock in the
598 if (!trylock_page(page)) {
603 ret = split_huge_page(page);
607 /* If split failed leave the inode on the list */
613 list_del_init(&info->shrinklist);
619 spin_lock(&sbinfo->shrinklist_lock);
620 list_splice_tail(&list, &sbinfo->shrinklist);
621 sbinfo->shrinklist_len -= removed;
622 spin_unlock(&sbinfo->shrinklist_lock);
627 static long shmem_unused_huge_scan(struct super_block *sb,
628 struct shrink_control *sc)
630 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
632 if (!READ_ONCE(sbinfo->shrinklist_len))
635 return shmem_unused_huge_shrink(sbinfo, sc, 0);
638 static long shmem_unused_huge_count(struct super_block *sb,
639 struct shrink_control *sc)
641 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
642 return READ_ONCE(sbinfo->shrinklist_len);
644 #else /* !CONFIG_TRANSPARENT_HUGEPAGE */
646 #define shmem_huge SHMEM_HUGE_DENY
648 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
649 struct shrink_control *sc, unsigned long nr_to_split)
653 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
655 static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo)
657 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
658 (shmem_huge == SHMEM_HUGE_FORCE || sbinfo->huge) &&
659 shmem_huge != SHMEM_HUGE_DENY)
665 * Like add_to_page_cache_locked, but error if expected item has gone.
667 static int shmem_add_to_page_cache(struct page *page,
668 struct address_space *mapping,
669 pgoff_t index, void *expected, gfp_t gfp,
670 struct mm_struct *charge_mm)
672 XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page));
674 unsigned long nr = compound_nr(page);
677 VM_BUG_ON_PAGE(PageTail(page), page);
678 VM_BUG_ON_PAGE(index != round_down(index, nr), page);
679 VM_BUG_ON_PAGE(!PageLocked(page), page);
680 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
681 VM_BUG_ON(expected && PageTransHuge(page));
683 page_ref_add(page, nr);
684 page->mapping = mapping;
687 if (!PageSwapCache(page)) {
688 error = mem_cgroup_charge(page, charge_mm, gfp);
690 if (PageTransHuge(page)) {
691 count_vm_event(THP_FILE_FALLBACK);
692 count_vm_event(THP_FILE_FALLBACK_CHARGE);
697 cgroup_throttle_swaprate(page, gfp);
702 entry = xas_find_conflict(&xas);
703 if (entry != expected)
704 xas_set_err(&xas, -EEXIST);
705 xas_create_range(&xas);
709 xas_store(&xas, page);
714 if (PageTransHuge(page)) {
715 count_vm_event(THP_FILE_ALLOC);
716 __mod_lruvec_page_state(page, NR_SHMEM_THPS, nr);
718 mapping->nrpages += nr;
719 __mod_lruvec_page_state(page, NR_FILE_PAGES, nr);
720 __mod_lruvec_page_state(page, NR_SHMEM, nr);
722 xas_unlock_irq(&xas);
723 } while (xas_nomem(&xas, gfp));
725 if (xas_error(&xas)) {
726 error = xas_error(&xas);
732 page->mapping = NULL;
733 page_ref_sub(page, nr);
738 * Like delete_from_page_cache, but substitutes swap for page.
740 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
742 struct address_space *mapping = page->mapping;
745 VM_BUG_ON_PAGE(PageCompound(page), page);
747 xa_lock_irq(&mapping->i_pages);
748 error = shmem_replace_entry(mapping, page->index, page, radswap);
749 page->mapping = NULL;
751 __dec_lruvec_page_state(page, NR_FILE_PAGES);
752 __dec_lruvec_page_state(page, NR_SHMEM);
753 xa_unlock_irq(&mapping->i_pages);
759 * Remove swap entry from page cache, free the swap and its page cache.
761 static int shmem_free_swap(struct address_space *mapping,
762 pgoff_t index, void *radswap)
766 old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
769 free_swap_and_cache(radix_to_swp_entry(radswap));
774 * Determine (in bytes) how many of the shmem object's pages mapped by the
775 * given offsets are swapped out.
777 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
778 * as long as the inode doesn't go away and racy results are not a problem.
780 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
781 pgoff_t start, pgoff_t end)
783 XA_STATE(xas, &mapping->i_pages, start);
785 unsigned long swapped = 0;
788 xas_for_each(&xas, page, end - 1) {
789 if (xas_retry(&xas, page))
791 if (xa_is_value(page))
794 if (need_resched()) {
802 return swapped << PAGE_SHIFT;
806 * Determine (in bytes) how many of the shmem object's pages mapped by the
807 * given vma is swapped out.
809 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
810 * as long as the inode doesn't go away and racy results are not a problem.
812 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
814 struct inode *inode = file_inode(vma->vm_file);
815 struct shmem_inode_info *info = SHMEM_I(inode);
816 struct address_space *mapping = inode->i_mapping;
817 unsigned long swapped;
819 /* Be careful as we don't hold info->lock */
820 swapped = READ_ONCE(info->swapped);
823 * The easier cases are when the shmem object has nothing in swap, or
824 * the vma maps it whole. Then we can simply use the stats that we
830 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
831 return swapped << PAGE_SHIFT;
833 /* Here comes the more involved part */
834 return shmem_partial_swap_usage(mapping,
835 linear_page_index(vma, vma->vm_start),
836 linear_page_index(vma, vma->vm_end));
840 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
842 void shmem_unlock_mapping(struct address_space *mapping)
849 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
851 while (!mapping_unevictable(mapping)) {
852 if (!pagevec_lookup(&pvec, mapping, &index))
854 check_move_unevictable_pages(&pvec);
855 pagevec_release(&pvec);
861 * Check whether a hole-punch or truncation needs to split a huge page,
862 * returning true if no split was required, or the split has been successful.
864 * Eviction (or truncation to 0 size) should never need to split a huge page;
865 * but in rare cases might do so, if shmem_undo_range() failed to trylock on
866 * head, and then succeeded to trylock on tail.
868 * A split can only succeed when there are no additional references on the
869 * huge page: so the split below relies upon find_get_entries() having stopped
870 * when it found a subpage of the huge page, without getting further references.
872 static bool shmem_punch_compound(struct page *page, pgoff_t start, pgoff_t end)
874 if (!PageTransCompound(page))
877 /* Just proceed to delete a huge page wholly within the range punched */
878 if (PageHead(page) &&
879 page->index >= start && page->index + HPAGE_PMD_NR <= end)
882 /* Try to split huge page, so we can truly punch the hole or truncate */
883 return split_huge_page(page) >= 0;
887 * Remove range of pages and swap entries from page cache, and free them.
888 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
890 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
893 struct address_space *mapping = inode->i_mapping;
894 struct shmem_inode_info *info = SHMEM_I(inode);
895 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
896 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
897 unsigned int partial_start = lstart & (PAGE_SIZE - 1);
898 unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
900 pgoff_t indices[PAGEVEC_SIZE];
901 long nr_swaps_freed = 0;
906 end = -1; /* unsigned, so actually very big */
910 while (index < end && find_lock_entries(mapping, index, end - 1,
912 for (i = 0; i < pagevec_count(&pvec); i++) {
913 struct page *page = pvec.pages[i];
917 if (xa_is_value(page)) {
920 nr_swaps_freed += !shmem_free_swap(mapping,
924 index += thp_nr_pages(page) - 1;
926 if (!unfalloc || !PageUptodate(page))
927 truncate_inode_page(mapping, page);
930 pagevec_remove_exceptionals(&pvec);
931 pagevec_release(&pvec);
937 struct page *page = NULL;
938 shmem_getpage(inode, start - 1, &page, SGP_READ);
940 unsigned int top = PAGE_SIZE;
945 zero_user_segment(page, partial_start, top);
946 set_page_dirty(page);
952 struct page *page = NULL;
953 shmem_getpage(inode, end, &page, SGP_READ);
955 zero_user_segment(page, 0, partial_end);
956 set_page_dirty(page);
965 while (index < end) {
968 if (!find_get_entries(mapping, index, end - 1, &pvec,
970 /* If all gone or hole-punch or unfalloc, we're done */
971 if (index == start || end != -1)
973 /* But if truncating, restart to make sure all gone */
977 for (i = 0; i < pagevec_count(&pvec); i++) {
978 struct page *page = pvec.pages[i];
981 if (xa_is_value(page)) {
984 if (shmem_free_swap(mapping, index, page)) {
985 /* Swap was replaced by page: retry */
995 if (!unfalloc || !PageUptodate(page)) {
996 if (page_mapping(page) != mapping) {
997 /* Page was replaced by swap: retry */
1002 VM_BUG_ON_PAGE(PageWriteback(page), page);
1003 if (shmem_punch_compound(page, start, end))
1004 truncate_inode_page(mapping, page);
1005 else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1006 /* Wipe the page and don't get stuck */
1007 clear_highpage(page);
1008 flush_dcache_page(page);
1009 set_page_dirty(page);
1011 round_up(start, HPAGE_PMD_NR))
1017 pagevec_remove_exceptionals(&pvec);
1018 pagevec_release(&pvec);
1022 spin_lock_irq(&info->lock);
1023 info->swapped -= nr_swaps_freed;
1024 shmem_recalc_inode(inode);
1025 spin_unlock_irq(&info->lock);
1028 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1030 shmem_undo_range(inode, lstart, lend, false);
1031 inode->i_ctime = inode->i_mtime = current_time(inode);
1033 EXPORT_SYMBOL_GPL(shmem_truncate_range);
1035 static int shmem_getattr(struct user_namespace *mnt_userns,
1036 const struct path *path, struct kstat *stat,
1037 u32 request_mask, unsigned int query_flags)
1039 struct inode *inode = path->dentry->d_inode;
1040 struct shmem_inode_info *info = SHMEM_I(inode);
1041 struct shmem_sb_info *sb_info = SHMEM_SB(inode->i_sb);
1043 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
1044 spin_lock_irq(&info->lock);
1045 shmem_recalc_inode(inode);
1046 spin_unlock_irq(&info->lock);
1048 generic_fillattr(&init_user_ns, inode, stat);
1050 if (is_huge_enabled(sb_info))
1051 stat->blksize = HPAGE_PMD_SIZE;
1056 static int shmem_setattr(struct user_namespace *mnt_userns,
1057 struct dentry *dentry, struct iattr *attr)
1059 struct inode *inode = d_inode(dentry);
1060 struct shmem_inode_info *info = SHMEM_I(inode);
1061 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1064 error = setattr_prepare(&init_user_ns, dentry, attr);
1068 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1069 loff_t oldsize = inode->i_size;
1070 loff_t newsize = attr->ia_size;
1072 /* protected by i_mutex */
1073 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1074 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1077 if (newsize != oldsize) {
1078 error = shmem_reacct_size(SHMEM_I(inode)->flags,
1082 i_size_write(inode, newsize);
1083 inode->i_ctime = inode->i_mtime = current_time(inode);
1085 if (newsize <= oldsize) {
1086 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1087 if (oldsize > holebegin)
1088 unmap_mapping_range(inode->i_mapping,
1091 shmem_truncate_range(inode,
1092 newsize, (loff_t)-1);
1093 /* unmap again to remove racily COWed private pages */
1094 if (oldsize > holebegin)
1095 unmap_mapping_range(inode->i_mapping,
1099 * Part of the huge page can be beyond i_size: subject
1100 * to shrink under memory pressure.
1102 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1103 spin_lock(&sbinfo->shrinklist_lock);
1105 * _careful to defend against unlocked access to
1106 * ->shrink_list in shmem_unused_huge_shrink()
1108 if (list_empty_careful(&info->shrinklist)) {
1109 list_add_tail(&info->shrinklist,
1110 &sbinfo->shrinklist);
1111 sbinfo->shrinklist_len++;
1113 spin_unlock(&sbinfo->shrinklist_lock);
1118 setattr_copy(&init_user_ns, inode, attr);
1119 if (attr->ia_valid & ATTR_MODE)
1120 error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
1124 static void shmem_evict_inode(struct inode *inode)
1126 struct shmem_inode_info *info = SHMEM_I(inode);
1127 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1129 if (shmem_mapping(inode->i_mapping)) {
1130 shmem_unacct_size(info->flags, inode->i_size);
1132 shmem_truncate_range(inode, 0, (loff_t)-1);
1133 if (!list_empty(&info->shrinklist)) {
1134 spin_lock(&sbinfo->shrinklist_lock);
1135 if (!list_empty(&info->shrinklist)) {
1136 list_del_init(&info->shrinklist);
1137 sbinfo->shrinklist_len--;
1139 spin_unlock(&sbinfo->shrinklist_lock);
1141 while (!list_empty(&info->swaplist)) {
1142 /* Wait while shmem_unuse() is scanning this inode... */
1143 wait_var_event(&info->stop_eviction,
1144 !atomic_read(&info->stop_eviction));
1145 mutex_lock(&shmem_swaplist_mutex);
1146 /* ...but beware of the race if we peeked too early */
1147 if (!atomic_read(&info->stop_eviction))
1148 list_del_init(&info->swaplist);
1149 mutex_unlock(&shmem_swaplist_mutex);
1153 simple_xattrs_free(&info->xattrs);
1154 WARN_ON(inode->i_blocks);
1155 shmem_free_inode(inode->i_sb);
1159 extern struct swap_info_struct *swap_info[];
1161 static int shmem_find_swap_entries(struct address_space *mapping,
1162 pgoff_t start, unsigned int nr_entries,
1163 struct page **entries, pgoff_t *indices,
1164 unsigned int type, bool frontswap)
1166 XA_STATE(xas, &mapping->i_pages, start);
1169 unsigned int ret = 0;
1175 xas_for_each(&xas, page, ULONG_MAX) {
1176 if (xas_retry(&xas, page))
1179 if (!xa_is_value(page))
1182 entry = radix_to_swp_entry(page);
1183 if (swp_type(entry) != type)
1186 !frontswap_test(swap_info[type], swp_offset(entry)))
1189 indices[ret] = xas.xa_index;
1190 entries[ret] = page;
1192 if (need_resched()) {
1196 if (++ret == nr_entries)
1205 * Move the swapped pages for an inode to page cache. Returns the count
1206 * of pages swapped in, or the error in case of failure.
1208 static int shmem_unuse_swap_entries(struct inode *inode, struct pagevec pvec,
1214 struct address_space *mapping = inode->i_mapping;
1216 for (i = 0; i < pvec.nr; i++) {
1217 struct page *page = pvec.pages[i];
1219 if (!xa_is_value(page))
1221 error = shmem_swapin_page(inode, indices[i],
1223 mapping_gfp_mask(mapping),
1230 if (error == -ENOMEM)
1234 return error ? error : ret;
1238 * If swap found in inode, free it and move page from swapcache to filecache.
1240 static int shmem_unuse_inode(struct inode *inode, unsigned int type,
1241 bool frontswap, unsigned long *fs_pages_to_unuse)
1243 struct address_space *mapping = inode->i_mapping;
1245 struct pagevec pvec;
1246 pgoff_t indices[PAGEVEC_SIZE];
1247 bool frontswap_partial = (frontswap && *fs_pages_to_unuse > 0);
1250 pagevec_init(&pvec);
1252 unsigned int nr_entries = PAGEVEC_SIZE;
1254 if (frontswap_partial && *fs_pages_to_unuse < PAGEVEC_SIZE)
1255 nr_entries = *fs_pages_to_unuse;
1257 pvec.nr = shmem_find_swap_entries(mapping, start, nr_entries,
1258 pvec.pages, indices,
1265 ret = shmem_unuse_swap_entries(inode, pvec, indices);
1269 if (frontswap_partial) {
1270 *fs_pages_to_unuse -= ret;
1271 if (*fs_pages_to_unuse == 0) {
1272 ret = FRONTSWAP_PAGES_UNUSED;
1277 start = indices[pvec.nr - 1];
1284 * Read all the shared memory data that resides in the swap
1285 * device 'type' back into memory, so the swap device can be
1288 int shmem_unuse(unsigned int type, bool frontswap,
1289 unsigned long *fs_pages_to_unuse)
1291 struct shmem_inode_info *info, *next;
1294 if (list_empty(&shmem_swaplist))
1297 mutex_lock(&shmem_swaplist_mutex);
1298 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1299 if (!info->swapped) {
1300 list_del_init(&info->swaplist);
1304 * Drop the swaplist mutex while searching the inode for swap;
1305 * but before doing so, make sure shmem_evict_inode() will not
1306 * remove placeholder inode from swaplist, nor let it be freed
1307 * (igrab() would protect from unlink, but not from unmount).
1309 atomic_inc(&info->stop_eviction);
1310 mutex_unlock(&shmem_swaplist_mutex);
1312 error = shmem_unuse_inode(&info->vfs_inode, type, frontswap,
1316 mutex_lock(&shmem_swaplist_mutex);
1317 next = list_next_entry(info, swaplist);
1319 list_del_init(&info->swaplist);
1320 if (atomic_dec_and_test(&info->stop_eviction))
1321 wake_up_var(&info->stop_eviction);
1325 mutex_unlock(&shmem_swaplist_mutex);
1331 * Move the page from the page cache to the swap cache.
1333 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1335 struct shmem_inode_info *info;
1336 struct address_space *mapping;
1337 struct inode *inode;
1341 VM_BUG_ON_PAGE(PageCompound(page), page);
1342 BUG_ON(!PageLocked(page));
1343 mapping = page->mapping;
1344 index = page->index;
1345 inode = mapping->host;
1346 info = SHMEM_I(inode);
1347 if (info->flags & VM_LOCKED)
1349 if (!total_swap_pages)
1353 * Our capabilities prevent regular writeback or sync from ever calling
1354 * shmem_writepage; but a stacking filesystem might use ->writepage of
1355 * its underlying filesystem, in which case tmpfs should write out to
1356 * swap only in response to memory pressure, and not for the writeback
1359 if (!wbc->for_reclaim) {
1360 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1365 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1366 * value into swapfile.c, the only way we can correctly account for a
1367 * fallocated page arriving here is now to initialize it and write it.
1369 * That's okay for a page already fallocated earlier, but if we have
1370 * not yet completed the fallocation, then (a) we want to keep track
1371 * of this page in case we have to undo it, and (b) it may not be a
1372 * good idea to continue anyway, once we're pushing into swap. So
1373 * reactivate the page, and let shmem_fallocate() quit when too many.
1375 if (!PageUptodate(page)) {
1376 if (inode->i_private) {
1377 struct shmem_falloc *shmem_falloc;
1378 spin_lock(&inode->i_lock);
1379 shmem_falloc = inode->i_private;
1381 !shmem_falloc->waitq &&
1382 index >= shmem_falloc->start &&
1383 index < shmem_falloc->next)
1384 shmem_falloc->nr_unswapped++;
1386 shmem_falloc = NULL;
1387 spin_unlock(&inode->i_lock);
1391 clear_highpage(page);
1392 flush_dcache_page(page);
1393 SetPageUptodate(page);
1396 swap = get_swap_page(page);
1401 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1402 * if it's not already there. Do it now before the page is
1403 * moved to swap cache, when its pagelock no longer protects
1404 * the inode from eviction. But don't unlock the mutex until
1405 * we've incremented swapped, because shmem_unuse_inode() will
1406 * prune a !swapped inode from the swaplist under this mutex.
1408 mutex_lock(&shmem_swaplist_mutex);
1409 if (list_empty(&info->swaplist))
1410 list_add(&info->swaplist, &shmem_swaplist);
1412 if (add_to_swap_cache(page, swap,
1413 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN,
1415 spin_lock_irq(&info->lock);
1416 shmem_recalc_inode(inode);
1418 spin_unlock_irq(&info->lock);
1420 swap_shmem_alloc(swap);
1421 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1423 mutex_unlock(&shmem_swaplist_mutex);
1424 BUG_ON(page_mapped(page));
1425 swap_writepage(page, wbc);
1429 mutex_unlock(&shmem_swaplist_mutex);
1430 put_swap_page(page, swap);
1432 set_page_dirty(page);
1433 if (wbc->for_reclaim)
1434 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1439 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1440 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1444 if (!mpol || mpol->mode == MPOL_DEFAULT)
1445 return; /* show nothing */
1447 mpol_to_str(buffer, sizeof(buffer), mpol);
1449 seq_printf(seq, ",mpol=%s", buffer);
1452 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1454 struct mempolicy *mpol = NULL;
1456 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1457 mpol = sbinfo->mpol;
1459 spin_unlock(&sbinfo->stat_lock);
1463 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1464 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1467 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1471 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1473 #define vm_policy vm_private_data
1476 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1477 struct shmem_inode_info *info, pgoff_t index)
1479 /* Create a pseudo vma that just contains the policy */
1480 vma_init(vma, NULL);
1481 /* Bias interleave by inode number to distribute better across nodes */
1482 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1483 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1486 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1488 /* Drop reference taken by mpol_shared_policy_lookup() */
1489 mpol_cond_put(vma->vm_policy);
1492 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1493 struct shmem_inode_info *info, pgoff_t index)
1495 struct vm_area_struct pvma;
1497 struct vm_fault vmf = {
1501 shmem_pseudo_vma_init(&pvma, info, index);
1502 page = swap_cluster_readahead(swap, gfp, &vmf);
1503 shmem_pseudo_vma_destroy(&pvma);
1509 * Make sure huge_gfp is always more limited than limit_gfp.
1510 * Some of the flags set permissions, while others set limitations.
1512 static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1514 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1515 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1516 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1517 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1519 /* Allow allocations only from the originally specified zones. */
1520 result |= zoneflags;
1523 * Minimize the result gfp by taking the union with the deny flags,
1524 * and the intersection of the allow flags.
1526 result |= (limit_gfp & denyflags);
1527 result |= (huge_gfp & limit_gfp) & allowflags;
1532 static struct page *shmem_alloc_hugepage(gfp_t gfp,
1533 struct shmem_inode_info *info, pgoff_t index)
1535 struct vm_area_struct pvma;
1536 struct address_space *mapping = info->vfs_inode.i_mapping;
1540 hindex = round_down(index, HPAGE_PMD_NR);
1541 if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1,
1545 shmem_pseudo_vma_init(&pvma, info, hindex);
1546 page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(),
1548 shmem_pseudo_vma_destroy(&pvma);
1550 prep_transhuge_page(page);
1552 count_vm_event(THP_FILE_FALLBACK);
1556 static struct page *shmem_alloc_page(gfp_t gfp,
1557 struct shmem_inode_info *info, pgoff_t index)
1559 struct vm_area_struct pvma;
1562 shmem_pseudo_vma_init(&pvma, info, index);
1563 page = alloc_page_vma(gfp, &pvma, 0);
1564 shmem_pseudo_vma_destroy(&pvma);
1569 static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1570 struct inode *inode,
1571 pgoff_t index, bool huge)
1573 struct shmem_inode_info *info = SHMEM_I(inode);
1578 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1580 nr = huge ? HPAGE_PMD_NR : 1;
1582 if (!shmem_inode_acct_block(inode, nr))
1586 page = shmem_alloc_hugepage(gfp, info, index);
1588 page = shmem_alloc_page(gfp, info, index);
1590 __SetPageLocked(page);
1591 __SetPageSwapBacked(page);
1596 shmem_inode_unacct_blocks(inode, nr);
1598 return ERR_PTR(err);
1602 * When a page is moved from swapcache to shmem filecache (either by the
1603 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1604 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1605 * ignorance of the mapping it belongs to. If that mapping has special
1606 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1607 * we may need to copy to a suitable page before moving to filecache.
1609 * In a future release, this may well be extended to respect cpuset and
1610 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1611 * but for now it is a simple matter of zone.
1613 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1615 return page_zonenum(page) > gfp_zone(gfp);
1618 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1619 struct shmem_inode_info *info, pgoff_t index)
1621 struct page *oldpage, *newpage;
1622 struct address_space *swap_mapping;
1628 entry.val = page_private(oldpage);
1629 swap_index = swp_offset(entry);
1630 swap_mapping = page_mapping(oldpage);
1633 * We have arrived here because our zones are constrained, so don't
1634 * limit chance of success by further cpuset and node constraints.
1636 gfp &= ~GFP_CONSTRAINT_MASK;
1637 newpage = shmem_alloc_page(gfp, info, index);
1642 copy_highpage(newpage, oldpage);
1643 flush_dcache_page(newpage);
1645 __SetPageLocked(newpage);
1646 __SetPageSwapBacked(newpage);
1647 SetPageUptodate(newpage);
1648 set_page_private(newpage, entry.val);
1649 SetPageSwapCache(newpage);
1652 * Our caller will very soon move newpage out of swapcache, but it's
1653 * a nice clean interface for us to replace oldpage by newpage there.
1655 xa_lock_irq(&swap_mapping->i_pages);
1656 error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage);
1658 mem_cgroup_migrate(oldpage, newpage);
1659 __inc_lruvec_page_state(newpage, NR_FILE_PAGES);
1660 __dec_lruvec_page_state(oldpage, NR_FILE_PAGES);
1662 xa_unlock_irq(&swap_mapping->i_pages);
1664 if (unlikely(error)) {
1666 * Is this possible? I think not, now that our callers check
1667 * both PageSwapCache and page_private after getting page lock;
1668 * but be defensive. Reverse old to newpage for clear and free.
1672 lru_cache_add(newpage);
1676 ClearPageSwapCache(oldpage);
1677 set_page_private(oldpage, 0);
1679 unlock_page(oldpage);
1686 * Swap in the page pointed to by *pagep.
1687 * Caller has to make sure that *pagep contains a valid swapped page.
1688 * Returns 0 and the page in pagep if success. On failure, returns the
1689 * error code and NULL in *pagep.
1691 static int shmem_swapin_page(struct inode *inode, pgoff_t index,
1692 struct page **pagep, enum sgp_type sgp,
1693 gfp_t gfp, struct vm_area_struct *vma,
1694 vm_fault_t *fault_type)
1696 struct address_space *mapping = inode->i_mapping;
1697 struct shmem_inode_info *info = SHMEM_I(inode);
1698 struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm;
1703 VM_BUG_ON(!*pagep || !xa_is_value(*pagep));
1704 swap = radix_to_swp_entry(*pagep);
1707 /* Look it up and read it in.. */
1708 page = lookup_swap_cache(swap, NULL, 0);
1710 /* Or update major stats only when swapin succeeds?? */
1712 *fault_type |= VM_FAULT_MAJOR;
1713 count_vm_event(PGMAJFAULT);
1714 count_memcg_event_mm(charge_mm, PGMAJFAULT);
1716 /* Here we actually start the io */
1717 page = shmem_swapin(swap, gfp, info, index);
1724 /* We have to do this with page locked to prevent races */
1726 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1727 !shmem_confirm_swap(mapping, index, swap)) {
1731 if (!PageUptodate(page)) {
1735 wait_on_page_writeback(page);
1738 * Some architectures may have to restore extra metadata to the
1739 * physical page after reading from swap.
1741 arch_swap_restore(swap, page);
1743 if (shmem_should_replace_page(page, gfp)) {
1744 error = shmem_replace_page(&page, gfp, info, index);
1749 error = shmem_add_to_page_cache(page, mapping, index,
1750 swp_to_radix_entry(swap), gfp,
1755 spin_lock_irq(&info->lock);
1757 shmem_recalc_inode(inode);
1758 spin_unlock_irq(&info->lock);
1760 if (sgp == SGP_WRITE)
1761 mark_page_accessed(page);
1763 delete_from_swap_cache(page);
1764 set_page_dirty(page);
1770 if (!shmem_confirm_swap(mapping, index, swap))
1782 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1784 * If we allocate a new one we do not mark it dirty. That's up to the
1785 * vm. If we swap it in we mark it dirty since we also free the swap
1786 * entry since a page cannot live in both the swap and page cache.
1788 * vmf and fault_type are only supplied by shmem_fault:
1789 * otherwise they are NULL.
1791 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1792 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1793 struct vm_area_struct *vma, struct vm_fault *vmf,
1794 vm_fault_t *fault_type)
1796 struct address_space *mapping = inode->i_mapping;
1797 struct shmem_inode_info *info = SHMEM_I(inode);
1798 struct shmem_sb_info *sbinfo;
1799 struct mm_struct *charge_mm;
1801 enum sgp_type sgp_huge = sgp;
1802 pgoff_t hindex = index;
1808 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1810 if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
1813 if (sgp <= SGP_CACHE &&
1814 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1818 sbinfo = SHMEM_SB(inode->i_sb);
1819 charge_mm = vma ? vma->vm_mm : current->mm;
1821 page = pagecache_get_page(mapping, index,
1822 FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0);
1823 if (xa_is_value(page)) {
1824 error = shmem_swapin_page(inode, index, &page,
1825 sgp, gfp, vma, fault_type);
1826 if (error == -EEXIST)
1834 hindex = page->index;
1835 if (page && sgp == SGP_WRITE)
1836 mark_page_accessed(page);
1838 /* fallocated page? */
1839 if (page && !PageUptodate(page)) {
1840 if (sgp != SGP_READ)
1847 if (page || sgp == SGP_READ)
1851 * Fast cache lookup did not find it:
1852 * bring it back from swap or allocate.
1855 if (vma && userfaultfd_missing(vma)) {
1856 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1860 /* shmem_symlink() */
1861 if (!shmem_mapping(mapping))
1863 if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
1865 if (shmem_huge == SHMEM_HUGE_FORCE)
1867 switch (sbinfo->huge) {
1868 case SHMEM_HUGE_NEVER:
1870 case SHMEM_HUGE_WITHIN_SIZE: {
1874 off = round_up(index, HPAGE_PMD_NR);
1875 i_size = round_up(i_size_read(inode), PAGE_SIZE);
1876 if (i_size >= HPAGE_PMD_SIZE &&
1877 i_size >> PAGE_SHIFT >= off)
1882 case SHMEM_HUGE_ADVISE:
1883 if (sgp_huge == SGP_HUGE)
1885 /* TODO: implement fadvise() hints */
1890 huge_gfp = vma_thp_gfp_mask(vma);
1891 huge_gfp = limit_gfp_mask(huge_gfp, gfp);
1892 page = shmem_alloc_and_acct_page(huge_gfp, inode, index, true);
1895 page = shmem_alloc_and_acct_page(gfp, inode,
1901 error = PTR_ERR(page);
1903 if (error != -ENOSPC)
1906 * Try to reclaim some space by splitting a huge page
1907 * beyond i_size on the filesystem.
1912 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1913 if (ret == SHRINK_STOP)
1921 if (PageTransHuge(page))
1922 hindex = round_down(index, HPAGE_PMD_NR);
1926 if (sgp == SGP_WRITE)
1927 __SetPageReferenced(page);
1929 error = shmem_add_to_page_cache(page, mapping, hindex,
1930 NULL, gfp & GFP_RECLAIM_MASK,
1934 lru_cache_add(page);
1936 spin_lock_irq(&info->lock);
1937 info->alloced += compound_nr(page);
1938 inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1939 shmem_recalc_inode(inode);
1940 spin_unlock_irq(&info->lock);
1943 if (PageTransHuge(page) &&
1944 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1945 hindex + HPAGE_PMD_NR - 1) {
1947 * Part of the huge page is beyond i_size: subject
1948 * to shrink under memory pressure.
1950 spin_lock(&sbinfo->shrinklist_lock);
1952 * _careful to defend against unlocked access to
1953 * ->shrink_list in shmem_unused_huge_shrink()
1955 if (list_empty_careful(&info->shrinklist)) {
1956 list_add_tail(&info->shrinklist,
1957 &sbinfo->shrinklist);
1958 sbinfo->shrinklist_len++;
1960 spin_unlock(&sbinfo->shrinklist_lock);
1964 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1966 if (sgp == SGP_FALLOC)
1970 * Let SGP_WRITE caller clear ends if write does not fill page;
1971 * but SGP_FALLOC on a page fallocated earlier must initialize
1972 * it now, lest undo on failure cancel our earlier guarantee.
1974 if (sgp != SGP_WRITE && !PageUptodate(page)) {
1977 for (i = 0; i < compound_nr(page); i++) {
1978 clear_highpage(page + i);
1979 flush_dcache_page(page + i);
1981 SetPageUptodate(page);
1984 /* Perhaps the file has been truncated since we checked */
1985 if (sgp <= SGP_CACHE &&
1986 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1988 ClearPageDirty(page);
1989 delete_from_page_cache(page);
1990 spin_lock_irq(&info->lock);
1991 shmem_recalc_inode(inode);
1992 spin_unlock_irq(&info->lock);
1998 *pagep = page + index - hindex;
2005 shmem_inode_unacct_blocks(inode, compound_nr(page));
2007 if (PageTransHuge(page)) {
2017 if (error == -ENOSPC && !once++) {
2018 spin_lock_irq(&info->lock);
2019 shmem_recalc_inode(inode);
2020 spin_unlock_irq(&info->lock);
2023 if (error == -EEXIST)
2029 * This is like autoremove_wake_function, but it removes the wait queue
2030 * entry unconditionally - even if something else had already woken the
2033 static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
2035 int ret = default_wake_function(wait, mode, sync, key);
2036 list_del_init(&wait->entry);
2040 static vm_fault_t shmem_fault(struct vm_fault *vmf)
2042 struct vm_area_struct *vma = vmf->vma;
2043 struct inode *inode = file_inode(vma->vm_file);
2044 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
2047 vm_fault_t ret = VM_FAULT_LOCKED;
2050 * Trinity finds that probing a hole which tmpfs is punching can
2051 * prevent the hole-punch from ever completing: which in turn
2052 * locks writers out with its hold on i_mutex. So refrain from
2053 * faulting pages into the hole while it's being punched. Although
2054 * shmem_undo_range() does remove the additions, it may be unable to
2055 * keep up, as each new page needs its own unmap_mapping_range() call,
2056 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2058 * It does not matter if we sometimes reach this check just before the
2059 * hole-punch begins, so that one fault then races with the punch:
2060 * we just need to make racing faults a rare case.
2062 * The implementation below would be much simpler if we just used a
2063 * standard mutex or completion: but we cannot take i_mutex in fault,
2064 * and bloating every shmem inode for this unlikely case would be sad.
2066 if (unlikely(inode->i_private)) {
2067 struct shmem_falloc *shmem_falloc;
2069 spin_lock(&inode->i_lock);
2070 shmem_falloc = inode->i_private;
2072 shmem_falloc->waitq &&
2073 vmf->pgoff >= shmem_falloc->start &&
2074 vmf->pgoff < shmem_falloc->next) {
2076 wait_queue_head_t *shmem_falloc_waitq;
2077 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2079 ret = VM_FAULT_NOPAGE;
2080 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2082 ret = VM_FAULT_RETRY;
2084 shmem_falloc_waitq = shmem_falloc->waitq;
2085 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
2086 TASK_UNINTERRUPTIBLE);
2087 spin_unlock(&inode->i_lock);
2091 * shmem_falloc_waitq points into the shmem_fallocate()
2092 * stack of the hole-punching task: shmem_falloc_waitq
2093 * is usually invalid by the time we reach here, but
2094 * finish_wait() does not dereference it in that case;
2095 * though i_lock needed lest racing with wake_up_all().
2097 spin_lock(&inode->i_lock);
2098 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
2099 spin_unlock(&inode->i_lock);
2105 spin_unlock(&inode->i_lock);
2110 if ((vma->vm_flags & VM_NOHUGEPAGE) ||
2111 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
2113 else if (vma->vm_flags & VM_HUGEPAGE)
2116 err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
2117 gfp, vma, vmf, &ret);
2119 return vmf_error(err);
2123 unsigned long shmem_get_unmapped_area(struct file *file,
2124 unsigned long uaddr, unsigned long len,
2125 unsigned long pgoff, unsigned long flags)
2127 unsigned long (*get_area)(struct file *,
2128 unsigned long, unsigned long, unsigned long, unsigned long);
2130 unsigned long offset;
2131 unsigned long inflated_len;
2132 unsigned long inflated_addr;
2133 unsigned long inflated_offset;
2135 if (len > TASK_SIZE)
2138 get_area = current->mm->get_unmapped_area;
2139 addr = get_area(file, uaddr, len, pgoff, flags);
2141 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2143 if (IS_ERR_VALUE(addr))
2145 if (addr & ~PAGE_MASK)
2147 if (addr > TASK_SIZE - len)
2150 if (shmem_huge == SHMEM_HUGE_DENY)
2152 if (len < HPAGE_PMD_SIZE)
2154 if (flags & MAP_FIXED)
2157 * Our priority is to support MAP_SHARED mapped hugely;
2158 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2159 * But if caller specified an address hint and we allocated area there
2160 * successfully, respect that as before.
2165 if (shmem_huge != SHMEM_HUGE_FORCE) {
2166 struct super_block *sb;
2169 VM_BUG_ON(file->f_op != &shmem_file_operations);
2170 sb = file_inode(file)->i_sb;
2173 * Called directly from mm/mmap.c, or drivers/char/mem.c
2174 * for "/dev/zero", to create a shared anonymous object.
2176 if (IS_ERR(shm_mnt))
2178 sb = shm_mnt->mnt_sb;
2180 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2184 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2185 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2187 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2190 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2191 if (inflated_len > TASK_SIZE)
2193 if (inflated_len < len)
2196 inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags);
2197 if (IS_ERR_VALUE(inflated_addr))
2199 if (inflated_addr & ~PAGE_MASK)
2202 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2203 inflated_addr += offset - inflated_offset;
2204 if (inflated_offset > offset)
2205 inflated_addr += HPAGE_PMD_SIZE;
2207 if (inflated_addr > TASK_SIZE - len)
2209 return inflated_addr;
2213 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2215 struct inode *inode = file_inode(vma->vm_file);
2216 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2219 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2222 struct inode *inode = file_inode(vma->vm_file);
2225 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2226 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2230 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2232 struct inode *inode = file_inode(file);
2233 struct shmem_inode_info *info = SHMEM_I(inode);
2234 int retval = -ENOMEM;
2237 * What serializes the accesses to info->flags?
2238 * ipc_lock_object() when called from shmctl_do_lock(),
2239 * no serialization needed when called from shm_destroy().
2241 if (lock && !(info->flags & VM_LOCKED)) {
2242 if (!user_shm_lock(inode->i_size, user))
2244 info->flags |= VM_LOCKED;
2245 mapping_set_unevictable(file->f_mapping);
2247 if (!lock && (info->flags & VM_LOCKED) && user) {
2248 user_shm_unlock(inode->i_size, user);
2249 info->flags &= ~VM_LOCKED;
2250 mapping_clear_unevictable(file->f_mapping);
2258 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2260 struct shmem_inode_info *info = SHMEM_I(file_inode(file));
2262 if (info->seals & F_SEAL_FUTURE_WRITE) {
2264 * New PROT_WRITE and MAP_SHARED mmaps are not allowed when
2265 * "future write" seal active.
2267 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE))
2271 * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as
2272 * MAP_SHARED and read-only, take care to not allow mprotect to
2273 * revert protections on such mappings. Do this only for shared
2274 * mappings. For private mappings, don't need to mask
2275 * VM_MAYWRITE as we still want them to be COW-writable.
2277 if (vma->vm_flags & VM_SHARED)
2278 vma->vm_flags &= ~(VM_MAYWRITE);
2281 /* arm64 - allow memory tagging on RAM-based files */
2282 vma->vm_flags |= VM_MTE_ALLOWED;
2284 file_accessed(file);
2285 vma->vm_ops = &shmem_vm_ops;
2286 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
2287 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2288 (vma->vm_end & HPAGE_PMD_MASK)) {
2289 khugepaged_enter(vma, vma->vm_flags);
2294 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2295 umode_t mode, dev_t dev, unsigned long flags)
2297 struct inode *inode;
2298 struct shmem_inode_info *info;
2299 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2302 if (shmem_reserve_inode(sb, &ino))
2305 inode = new_inode(sb);
2308 inode_init_owner(&init_user_ns, inode, dir, mode);
2309 inode->i_blocks = 0;
2310 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2311 inode->i_generation = prandom_u32();
2312 info = SHMEM_I(inode);
2313 memset(info, 0, (char *)inode - (char *)info);
2314 spin_lock_init(&info->lock);
2315 atomic_set(&info->stop_eviction, 0);
2316 info->seals = F_SEAL_SEAL;
2317 info->flags = flags & VM_NORESERVE;
2318 INIT_LIST_HEAD(&info->shrinklist);
2319 INIT_LIST_HEAD(&info->swaplist);
2320 simple_xattrs_init(&info->xattrs);
2321 cache_no_acl(inode);
2323 switch (mode & S_IFMT) {
2325 inode->i_op = &shmem_special_inode_operations;
2326 init_special_inode(inode, mode, dev);
2329 inode->i_mapping->a_ops = &shmem_aops;
2330 inode->i_op = &shmem_inode_operations;
2331 inode->i_fop = &shmem_file_operations;
2332 mpol_shared_policy_init(&info->policy,
2333 shmem_get_sbmpol(sbinfo));
2337 /* Some things misbehave if size == 0 on a directory */
2338 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2339 inode->i_op = &shmem_dir_inode_operations;
2340 inode->i_fop = &simple_dir_operations;
2344 * Must not load anything in the rbtree,
2345 * mpol_free_shared_policy will not be called.
2347 mpol_shared_policy_init(&info->policy, NULL);
2351 lockdep_annotate_inode_mutex_key(inode);
2353 shmem_free_inode(sb);
2357 static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2359 struct vm_area_struct *dst_vma,
2360 unsigned long dst_addr,
2361 unsigned long src_addr,
2363 struct page **pagep)
2365 struct inode *inode = file_inode(dst_vma->vm_file);
2366 struct shmem_inode_info *info = SHMEM_I(inode);
2367 struct address_space *mapping = inode->i_mapping;
2368 gfp_t gfp = mapping_gfp_mask(mapping);
2369 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2373 pte_t _dst_pte, *dst_pte;
2375 pgoff_t offset, max_off;
2378 if (!shmem_inode_acct_block(inode, 1))
2382 page = shmem_alloc_page(gfp, info, pgoff);
2384 goto out_unacct_blocks;
2386 if (!zeropage) { /* mcopy_atomic */
2387 page_kaddr = kmap_atomic(page);
2388 ret = copy_from_user(page_kaddr,
2389 (const void __user *)src_addr,
2391 kunmap_atomic(page_kaddr);
2393 /* fallback to copy_from_user outside mmap_lock */
2394 if (unlikely(ret)) {
2396 shmem_inode_unacct_blocks(inode, 1);
2397 /* don't free the page */
2400 } else { /* mfill_zeropage_atomic */
2401 clear_highpage(page);
2408 VM_BUG_ON(PageLocked(page) || PageSwapBacked(page));
2409 __SetPageLocked(page);
2410 __SetPageSwapBacked(page);
2411 __SetPageUptodate(page);
2414 offset = linear_page_index(dst_vma, dst_addr);
2415 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2416 if (unlikely(offset >= max_off))
2419 ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL,
2420 gfp & GFP_RECLAIM_MASK, dst_mm);
2424 _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
2425 if (dst_vma->vm_flags & VM_WRITE)
2426 _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
2429 * We don't set the pte dirty if the vma has no
2430 * VM_WRITE permission, so mark the page dirty or it
2431 * could be freed from under us. We could do it
2432 * unconditionally before unlock_page(), but doing it
2433 * only if VM_WRITE is not set is faster.
2435 set_page_dirty(page);
2438 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
2441 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2442 if (unlikely(offset >= max_off))
2443 goto out_release_unlock;
2446 if (!pte_none(*dst_pte))
2447 goto out_release_unlock;
2449 lru_cache_add(page);
2451 spin_lock_irq(&info->lock);
2453 inode->i_blocks += BLOCKS_PER_PAGE;
2454 shmem_recalc_inode(inode);
2455 spin_unlock_irq(&info->lock);
2457 inc_mm_counter(dst_mm, mm_counter_file(page));
2458 page_add_file_rmap(page, false);
2459 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
2461 /* No need to invalidate - it was non-present before */
2462 update_mmu_cache(dst_vma, dst_addr, dst_pte);
2463 pte_unmap_unlock(dst_pte, ptl);
2469 pte_unmap_unlock(dst_pte, ptl);
2470 ClearPageDirty(page);
2471 delete_from_page_cache(page);
2476 shmem_inode_unacct_blocks(inode, 1);
2480 int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
2482 struct vm_area_struct *dst_vma,
2483 unsigned long dst_addr,
2484 unsigned long src_addr,
2485 struct page **pagep)
2487 return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2488 dst_addr, src_addr, false, pagep);
2491 int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
2493 struct vm_area_struct *dst_vma,
2494 unsigned long dst_addr)
2496 struct page *page = NULL;
2498 return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2499 dst_addr, 0, true, &page);
2503 static const struct inode_operations shmem_symlink_inode_operations;
2504 static const struct inode_operations shmem_short_symlink_operations;
2506 #ifdef CONFIG_TMPFS_XATTR
2507 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2509 #define shmem_initxattrs NULL
2513 shmem_write_begin(struct file *file, struct address_space *mapping,
2514 loff_t pos, unsigned len, unsigned flags,
2515 struct page **pagep, void **fsdata)
2517 struct inode *inode = mapping->host;
2518 struct shmem_inode_info *info = SHMEM_I(inode);
2519 pgoff_t index = pos >> PAGE_SHIFT;
2521 /* i_mutex is held by caller */
2522 if (unlikely(info->seals & (F_SEAL_GROW |
2523 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
2524 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
2526 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2530 return shmem_getpage(inode, index, pagep, SGP_WRITE);
2534 shmem_write_end(struct file *file, struct address_space *mapping,
2535 loff_t pos, unsigned len, unsigned copied,
2536 struct page *page, void *fsdata)
2538 struct inode *inode = mapping->host;
2540 if (pos + copied > inode->i_size)
2541 i_size_write(inode, pos + copied);
2543 if (!PageUptodate(page)) {
2544 struct page *head = compound_head(page);
2545 if (PageTransCompound(page)) {
2548 for (i = 0; i < HPAGE_PMD_NR; i++) {
2549 if (head + i == page)
2551 clear_highpage(head + i);
2552 flush_dcache_page(head + i);
2555 if (copied < PAGE_SIZE) {
2556 unsigned from = pos & (PAGE_SIZE - 1);
2557 zero_user_segments(page, 0, from,
2558 from + copied, PAGE_SIZE);
2560 SetPageUptodate(head);
2562 set_page_dirty(page);
2569 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2571 struct file *file = iocb->ki_filp;
2572 struct inode *inode = file_inode(file);
2573 struct address_space *mapping = inode->i_mapping;
2575 unsigned long offset;
2576 enum sgp_type sgp = SGP_READ;
2579 loff_t *ppos = &iocb->ki_pos;
2582 * Might this read be for a stacking filesystem? Then when reading
2583 * holes of a sparse file, we actually need to allocate those pages,
2584 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2586 if (!iter_is_iovec(to))
2589 index = *ppos >> PAGE_SHIFT;
2590 offset = *ppos & ~PAGE_MASK;
2593 struct page *page = NULL;
2595 unsigned long nr, ret;
2596 loff_t i_size = i_size_read(inode);
2598 end_index = i_size >> PAGE_SHIFT;
2599 if (index > end_index)
2601 if (index == end_index) {
2602 nr = i_size & ~PAGE_MASK;
2607 error = shmem_getpage(inode, index, &page, sgp);
2609 if (error == -EINVAL)
2614 if (sgp == SGP_CACHE)
2615 set_page_dirty(page);
2620 * We must evaluate after, since reads (unlike writes)
2621 * are called without i_mutex protection against truncate
2624 i_size = i_size_read(inode);
2625 end_index = i_size >> PAGE_SHIFT;
2626 if (index == end_index) {
2627 nr = i_size & ~PAGE_MASK;
2638 * If users can be writing to this page using arbitrary
2639 * virtual addresses, take care about potential aliasing
2640 * before reading the page on the kernel side.
2642 if (mapping_writably_mapped(mapping))
2643 flush_dcache_page(page);
2645 * Mark the page accessed if we read the beginning.
2648 mark_page_accessed(page);
2650 page = ZERO_PAGE(0);
2655 * Ok, we have the page, and it's up-to-date, so
2656 * now we can copy it to user space...
2658 ret = copy_page_to_iter(page, offset, nr, to);
2661 index += offset >> PAGE_SHIFT;
2662 offset &= ~PAGE_MASK;
2665 if (!iov_iter_count(to))
2674 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2675 file_accessed(file);
2676 return retval ? retval : error;
2679 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2681 struct address_space *mapping = file->f_mapping;
2682 struct inode *inode = mapping->host;
2684 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2685 return generic_file_llseek_size(file, offset, whence,
2686 MAX_LFS_FILESIZE, i_size_read(inode));
2691 /* We're holding i_mutex so we can access i_size directly */
2692 offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence);
2694 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2695 inode_unlock(inode);
2699 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2702 struct inode *inode = file_inode(file);
2703 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2704 struct shmem_inode_info *info = SHMEM_I(inode);
2705 struct shmem_falloc shmem_falloc;
2706 pgoff_t start, index, end;
2709 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2714 if (mode & FALLOC_FL_PUNCH_HOLE) {
2715 struct address_space *mapping = file->f_mapping;
2716 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2717 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2718 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2720 /* protected by i_mutex */
2721 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
2726 shmem_falloc.waitq = &shmem_falloc_waitq;
2727 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
2728 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2729 spin_lock(&inode->i_lock);
2730 inode->i_private = &shmem_falloc;
2731 spin_unlock(&inode->i_lock);
2733 if ((u64)unmap_end > (u64)unmap_start)
2734 unmap_mapping_range(mapping, unmap_start,
2735 1 + unmap_end - unmap_start, 0);
2736 shmem_truncate_range(inode, offset, offset + len - 1);
2737 /* No need to unmap again: hole-punching leaves COWed pages */
2739 spin_lock(&inode->i_lock);
2740 inode->i_private = NULL;
2741 wake_up_all(&shmem_falloc_waitq);
2742 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2743 spin_unlock(&inode->i_lock);
2748 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2749 error = inode_newsize_ok(inode, offset + len);
2753 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2758 start = offset >> PAGE_SHIFT;
2759 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2760 /* Try to avoid a swapstorm if len is impossible to satisfy */
2761 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2766 shmem_falloc.waitq = NULL;
2767 shmem_falloc.start = start;
2768 shmem_falloc.next = start;
2769 shmem_falloc.nr_falloced = 0;
2770 shmem_falloc.nr_unswapped = 0;
2771 spin_lock(&inode->i_lock);
2772 inode->i_private = &shmem_falloc;
2773 spin_unlock(&inode->i_lock);
2775 for (index = start; index < end; index++) {
2779 * Good, the fallocate(2) manpage permits EINTR: we may have
2780 * been interrupted because we are using up too much memory.
2782 if (signal_pending(current))
2784 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2787 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2789 /* Remove the !PageUptodate pages we added */
2790 if (index > start) {
2791 shmem_undo_range(inode,
2792 (loff_t)start << PAGE_SHIFT,
2793 ((loff_t)index << PAGE_SHIFT) - 1, true);
2799 * Inform shmem_writepage() how far we have reached.
2800 * No need for lock or barrier: we have the page lock.
2802 shmem_falloc.next++;
2803 if (!PageUptodate(page))
2804 shmem_falloc.nr_falloced++;
2807 * If !PageUptodate, leave it that way so that freeable pages
2808 * can be recognized if we need to rollback on error later.
2809 * But set_page_dirty so that memory pressure will swap rather
2810 * than free the pages we are allocating (and SGP_CACHE pages
2811 * might still be clean: we now need to mark those dirty too).
2813 set_page_dirty(page);
2819 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2820 i_size_write(inode, offset + len);
2821 inode->i_ctime = current_time(inode);
2823 spin_lock(&inode->i_lock);
2824 inode->i_private = NULL;
2825 spin_unlock(&inode->i_lock);
2827 inode_unlock(inode);
2831 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2833 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2835 buf->f_type = TMPFS_MAGIC;
2836 buf->f_bsize = PAGE_SIZE;
2837 buf->f_namelen = NAME_MAX;
2838 if (sbinfo->max_blocks) {
2839 buf->f_blocks = sbinfo->max_blocks;
2841 buf->f_bfree = sbinfo->max_blocks -
2842 percpu_counter_sum(&sbinfo->used_blocks);
2844 if (sbinfo->max_inodes) {
2845 buf->f_files = sbinfo->max_inodes;
2846 buf->f_ffree = sbinfo->free_inodes;
2848 /* else leave those fields 0 like simple_statfs */
2853 * File creation. Allocate an inode, and we're done..
2856 shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
2857 struct dentry *dentry, umode_t mode, dev_t dev)
2859 struct inode *inode;
2860 int error = -ENOSPC;
2862 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2864 error = simple_acl_create(dir, inode);
2867 error = security_inode_init_security(inode, dir,
2869 shmem_initxattrs, NULL);
2870 if (error && error != -EOPNOTSUPP)
2874 dir->i_size += BOGO_DIRENT_SIZE;
2875 dir->i_ctime = dir->i_mtime = current_time(dir);
2876 d_instantiate(dentry, inode);
2877 dget(dentry); /* Extra count - pin the dentry in core */
2886 shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
2887 struct dentry *dentry, umode_t mode)
2889 struct inode *inode;
2890 int error = -ENOSPC;
2892 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2894 error = security_inode_init_security(inode, dir,
2896 shmem_initxattrs, NULL);
2897 if (error && error != -EOPNOTSUPP)
2899 error = simple_acl_create(dir, inode);
2902 d_tmpfile(dentry, inode);
2910 static int shmem_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
2911 struct dentry *dentry, umode_t mode)
2915 if ((error = shmem_mknod(&init_user_ns, dir, dentry,
2916 mode | S_IFDIR, 0)))
2922 static int shmem_create(struct user_namespace *mnt_userns, struct inode *dir,
2923 struct dentry *dentry, umode_t mode, bool excl)
2925 return shmem_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0);
2931 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2933 struct inode *inode = d_inode(old_dentry);
2937 * No ordinary (disk based) filesystem counts links as inodes;
2938 * but each new link needs a new dentry, pinning lowmem, and
2939 * tmpfs dentries cannot be pruned until they are unlinked.
2940 * But if an O_TMPFILE file is linked into the tmpfs, the
2941 * first link must skip that, to get the accounting right.
2943 if (inode->i_nlink) {
2944 ret = shmem_reserve_inode(inode->i_sb, NULL);
2949 dir->i_size += BOGO_DIRENT_SIZE;
2950 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2952 ihold(inode); /* New dentry reference */
2953 dget(dentry); /* Extra pinning count for the created dentry */
2954 d_instantiate(dentry, inode);
2959 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2961 struct inode *inode = d_inode(dentry);
2963 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2964 shmem_free_inode(inode->i_sb);
2966 dir->i_size -= BOGO_DIRENT_SIZE;
2967 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
2969 dput(dentry); /* Undo the count from "create" - this does all the work */
2973 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2975 if (!simple_empty(dentry))
2978 drop_nlink(d_inode(dentry));
2980 return shmem_unlink(dir, dentry);
2983 static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
2985 bool old_is_dir = d_is_dir(old_dentry);
2986 bool new_is_dir = d_is_dir(new_dentry);
2988 if (old_dir != new_dir && old_is_dir != new_is_dir) {
2990 drop_nlink(old_dir);
2993 drop_nlink(new_dir);
2997 old_dir->i_ctime = old_dir->i_mtime =
2998 new_dir->i_ctime = new_dir->i_mtime =
2999 d_inode(old_dentry)->i_ctime =
3000 d_inode(new_dentry)->i_ctime = current_time(old_dir);
3005 static int shmem_whiteout(struct user_namespace *mnt_userns,
3006 struct inode *old_dir, struct dentry *old_dentry)
3008 struct dentry *whiteout;
3011 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3015 error = shmem_mknod(&init_user_ns, old_dir, whiteout,
3016 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3022 * Cheat and hash the whiteout while the old dentry is still in
3023 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3025 * d_lookup() will consistently find one of them at this point,
3026 * not sure which one, but that isn't even important.
3033 * The VFS layer already does all the dentry stuff for rename,
3034 * we just have to decrement the usage count for the target if
3035 * it exists so that the VFS layer correctly free's it when it
3038 static int shmem_rename2(struct user_namespace *mnt_userns,
3039 struct inode *old_dir, struct dentry *old_dentry,
3040 struct inode *new_dir, struct dentry *new_dentry,
3043 struct inode *inode = d_inode(old_dentry);
3044 int they_are_dirs = S_ISDIR(inode->i_mode);
3046 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3049 if (flags & RENAME_EXCHANGE)
3050 return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
3052 if (!simple_empty(new_dentry))
3055 if (flags & RENAME_WHITEOUT) {
3058 error = shmem_whiteout(&init_user_ns, old_dir, old_dentry);
3063 if (d_really_is_positive(new_dentry)) {
3064 (void) shmem_unlink(new_dir, new_dentry);
3065 if (they_are_dirs) {
3066 drop_nlink(d_inode(new_dentry));
3067 drop_nlink(old_dir);
3069 } else if (they_are_dirs) {
3070 drop_nlink(old_dir);
3074 old_dir->i_size -= BOGO_DIRENT_SIZE;
3075 new_dir->i_size += BOGO_DIRENT_SIZE;
3076 old_dir->i_ctime = old_dir->i_mtime =
3077 new_dir->i_ctime = new_dir->i_mtime =
3078 inode->i_ctime = current_time(old_dir);
3082 static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir,
3083 struct dentry *dentry, const char *symname)
3087 struct inode *inode;
3090 len = strlen(symname) + 1;
3091 if (len > PAGE_SIZE)
3092 return -ENAMETOOLONG;
3094 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0,
3099 error = security_inode_init_security(inode, dir, &dentry->d_name,
3100 shmem_initxattrs, NULL);
3101 if (error && error != -EOPNOTSUPP) {
3106 inode->i_size = len-1;
3107 if (len <= SHORT_SYMLINK_LEN) {
3108 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3109 if (!inode->i_link) {
3113 inode->i_op = &shmem_short_symlink_operations;
3115 inode_nohighmem(inode);
3116 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3121 inode->i_mapping->a_ops = &shmem_aops;
3122 inode->i_op = &shmem_symlink_inode_operations;
3123 memcpy(page_address(page), symname, len);
3124 SetPageUptodate(page);
3125 set_page_dirty(page);
3129 dir->i_size += BOGO_DIRENT_SIZE;
3130 dir->i_ctime = dir->i_mtime = current_time(dir);
3131 d_instantiate(dentry, inode);
3136 static void shmem_put_link(void *arg)
3138 mark_page_accessed(arg);
3142 static const char *shmem_get_link(struct dentry *dentry,
3143 struct inode *inode,
3144 struct delayed_call *done)
3146 struct page *page = NULL;
3149 page = find_get_page(inode->i_mapping, 0);
3151 return ERR_PTR(-ECHILD);
3152 if (!PageUptodate(page)) {
3154 return ERR_PTR(-ECHILD);
3157 error = shmem_getpage(inode, 0, &page, SGP_READ);
3159 return ERR_PTR(error);
3162 set_delayed_call(done, shmem_put_link, page);
3163 return page_address(page);
3166 #ifdef CONFIG_TMPFS_XATTR
3168 * Superblocks without xattr inode operations may get some security.* xattr
3169 * support from the LSM "for free". As soon as we have any other xattrs
3170 * like ACLs, we also need to implement the security.* handlers at
3171 * filesystem level, though.
3175 * Callback for security_inode_init_security() for acquiring xattrs.
3177 static int shmem_initxattrs(struct inode *inode,
3178 const struct xattr *xattr_array,
3181 struct shmem_inode_info *info = SHMEM_I(inode);
3182 const struct xattr *xattr;
3183 struct simple_xattr *new_xattr;
3186 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3187 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3191 len = strlen(xattr->name) + 1;
3192 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3194 if (!new_xattr->name) {
3199 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3200 XATTR_SECURITY_PREFIX_LEN);
3201 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3204 simple_xattr_list_add(&info->xattrs, new_xattr);
3210 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3211 struct dentry *unused, struct inode *inode,
3212 const char *name, void *buffer, size_t size)
3214 struct shmem_inode_info *info = SHMEM_I(inode);
3216 name = xattr_full_name(handler, name);
3217 return simple_xattr_get(&info->xattrs, name, buffer, size);
3220 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3221 struct user_namespace *mnt_userns,
3222 struct dentry *unused, struct inode *inode,
3223 const char *name, const void *value,
3224 size_t size, int flags)
3226 struct shmem_inode_info *info = SHMEM_I(inode);
3228 name = xattr_full_name(handler, name);
3229 return simple_xattr_set(&info->xattrs, name, value, size, flags, NULL);
3232 static const struct xattr_handler shmem_security_xattr_handler = {
3233 .prefix = XATTR_SECURITY_PREFIX,
3234 .get = shmem_xattr_handler_get,
3235 .set = shmem_xattr_handler_set,
3238 static const struct xattr_handler shmem_trusted_xattr_handler = {
3239 .prefix = XATTR_TRUSTED_PREFIX,
3240 .get = shmem_xattr_handler_get,
3241 .set = shmem_xattr_handler_set,
3244 static const struct xattr_handler *shmem_xattr_handlers[] = {
3245 #ifdef CONFIG_TMPFS_POSIX_ACL
3246 &posix_acl_access_xattr_handler,
3247 &posix_acl_default_xattr_handler,
3249 &shmem_security_xattr_handler,
3250 &shmem_trusted_xattr_handler,
3254 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3256 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3257 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3259 #endif /* CONFIG_TMPFS_XATTR */
3261 static const struct inode_operations shmem_short_symlink_operations = {
3262 .get_link = simple_get_link,
3263 #ifdef CONFIG_TMPFS_XATTR
3264 .listxattr = shmem_listxattr,
3268 static const struct inode_operations shmem_symlink_inode_operations = {
3269 .get_link = shmem_get_link,
3270 #ifdef CONFIG_TMPFS_XATTR
3271 .listxattr = shmem_listxattr,
3275 static struct dentry *shmem_get_parent(struct dentry *child)
3277 return ERR_PTR(-ESTALE);
3280 static int shmem_match(struct inode *ino, void *vfh)
3284 inum = (inum << 32) | fh[1];
3285 return ino->i_ino == inum && fh[0] == ino->i_generation;
3288 /* Find any alias of inode, but prefer a hashed alias */
3289 static struct dentry *shmem_find_alias(struct inode *inode)
3291 struct dentry *alias = d_find_alias(inode);
3293 return alias ?: d_find_any_alias(inode);
3297 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3298 struct fid *fid, int fh_len, int fh_type)
3300 struct inode *inode;
3301 struct dentry *dentry = NULL;
3308 inum = (inum << 32) | fid->raw[1];
3310 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3311 shmem_match, fid->raw);
3313 dentry = shmem_find_alias(inode);
3320 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3321 struct inode *parent)
3325 return FILEID_INVALID;
3328 if (inode_unhashed(inode)) {
3329 /* Unfortunately insert_inode_hash is not idempotent,
3330 * so as we hash inodes here rather than at creation
3331 * time, we need a lock to ensure we only try
3334 static DEFINE_SPINLOCK(lock);
3336 if (inode_unhashed(inode))
3337 __insert_inode_hash(inode,
3338 inode->i_ino + inode->i_generation);
3342 fh[0] = inode->i_generation;
3343 fh[1] = inode->i_ino;
3344 fh[2] = ((__u64)inode->i_ino) >> 32;
3350 static const struct export_operations shmem_export_ops = {
3351 .get_parent = shmem_get_parent,
3352 .encode_fh = shmem_encode_fh,
3353 .fh_to_dentry = shmem_fh_to_dentry,
3369 static const struct constant_table shmem_param_enums_huge[] = {
3370 {"never", SHMEM_HUGE_NEVER },
3371 {"always", SHMEM_HUGE_ALWAYS },
3372 {"within_size", SHMEM_HUGE_WITHIN_SIZE },
3373 {"advise", SHMEM_HUGE_ADVISE },
3377 const struct fs_parameter_spec shmem_fs_parameters[] = {
3378 fsparam_u32 ("gid", Opt_gid),
3379 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
3380 fsparam_u32oct("mode", Opt_mode),
3381 fsparam_string("mpol", Opt_mpol),
3382 fsparam_string("nr_blocks", Opt_nr_blocks),
3383 fsparam_string("nr_inodes", Opt_nr_inodes),
3384 fsparam_string("size", Opt_size),
3385 fsparam_u32 ("uid", Opt_uid),
3386 fsparam_flag ("inode32", Opt_inode32),
3387 fsparam_flag ("inode64", Opt_inode64),
3391 static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
3393 struct shmem_options *ctx = fc->fs_private;
3394 struct fs_parse_result result;
3395 unsigned long long size;
3399 opt = fs_parse(fc, shmem_fs_parameters, param, &result);
3405 size = memparse(param->string, &rest);
3407 size <<= PAGE_SHIFT;
3408 size *= totalram_pages();
3414 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
3415 ctx->seen |= SHMEM_SEEN_BLOCKS;
3418 ctx->blocks = memparse(param->string, &rest);
3421 ctx->seen |= SHMEM_SEEN_BLOCKS;
3424 ctx->inodes = memparse(param->string, &rest);
3427 ctx->seen |= SHMEM_SEEN_INODES;
3430 ctx->mode = result.uint_32 & 07777;
3433 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
3434 if (!uid_valid(ctx->uid))
3438 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
3439 if (!gid_valid(ctx->gid))
3443 ctx->huge = result.uint_32;
3444 if (ctx->huge != SHMEM_HUGE_NEVER &&
3445 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
3446 has_transparent_hugepage()))
3447 goto unsupported_parameter;
3448 ctx->seen |= SHMEM_SEEN_HUGE;
3451 if (IS_ENABLED(CONFIG_NUMA)) {
3452 mpol_put(ctx->mpol);
3454 if (mpol_parse_str(param->string, &ctx->mpol))
3458 goto unsupported_parameter;
3460 ctx->full_inums = false;
3461 ctx->seen |= SHMEM_SEEN_INUMS;
3464 if (sizeof(ino_t) < 8) {
3466 "Cannot use inode64 with <64bit inums in kernel\n");
3468 ctx->full_inums = true;
3469 ctx->seen |= SHMEM_SEEN_INUMS;
3474 unsupported_parameter:
3475 return invalfc(fc, "Unsupported parameter '%s'", param->key);
3477 return invalfc(fc, "Bad value for '%s'", param->key);
3480 static int shmem_parse_options(struct fs_context *fc, void *data)
3482 char *options = data;
3485 int err = security_sb_eat_lsm_opts(options, &fc->security);
3490 while (options != NULL) {
3491 char *this_char = options;
3494 * NUL-terminate this option: unfortunately,
3495 * mount options form a comma-separated list,
3496 * but mpol's nodelist may also contain commas.
3498 options = strchr(options, ',');
3499 if (options == NULL)
3502 if (!isdigit(*options)) {
3508 char *value = strchr(this_char,'=');
3514 len = strlen(value);
3516 err = vfs_parse_fs_string(fc, this_char, value, len);
3525 * Reconfigure a shmem filesystem.
3527 * Note that we disallow change from limited->unlimited blocks/inodes while any
3528 * are in use; but we must separately disallow unlimited->limited, because in
3529 * that case we have no record of how much is already in use.
3531 static int shmem_reconfigure(struct fs_context *fc)
3533 struct shmem_options *ctx = fc->fs_private;
3534 struct shmem_sb_info *sbinfo = SHMEM_SB(fc->root->d_sb);
3535 unsigned long inodes;
3538 spin_lock(&sbinfo->stat_lock);
3539 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3540 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
3541 if (!sbinfo->max_blocks) {
3542 err = "Cannot retroactively limit size";
3545 if (percpu_counter_compare(&sbinfo->used_blocks,
3547 err = "Too small a size for current use";
3551 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
3552 if (!sbinfo->max_inodes) {
3553 err = "Cannot retroactively limit inodes";
3556 if (ctx->inodes < inodes) {
3557 err = "Too few inodes for current use";
3562 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
3563 sbinfo->next_ino > UINT_MAX) {
3564 err = "Current inum too high to switch to 32-bit inums";
3568 if (ctx->seen & SHMEM_SEEN_HUGE)
3569 sbinfo->huge = ctx->huge;
3570 if (ctx->seen & SHMEM_SEEN_INUMS)
3571 sbinfo->full_inums = ctx->full_inums;
3572 if (ctx->seen & SHMEM_SEEN_BLOCKS)
3573 sbinfo->max_blocks = ctx->blocks;
3574 if (ctx->seen & SHMEM_SEEN_INODES) {
3575 sbinfo->max_inodes = ctx->inodes;
3576 sbinfo->free_inodes = ctx->inodes - inodes;
3580 * Preserve previous mempolicy unless mpol remount option was specified.
3583 mpol_put(sbinfo->mpol);
3584 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
3587 spin_unlock(&sbinfo->stat_lock);
3590 spin_unlock(&sbinfo->stat_lock);
3591 return invalfc(fc, "%s", err);
3594 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3596 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3598 if (sbinfo->max_blocks != shmem_default_max_blocks())
3599 seq_printf(seq, ",size=%luk",
3600 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3601 if (sbinfo->max_inodes != shmem_default_max_inodes())
3602 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3603 if (sbinfo->mode != (0777 | S_ISVTX))
3604 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3605 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3606 seq_printf(seq, ",uid=%u",
3607 from_kuid_munged(&init_user_ns, sbinfo->uid));
3608 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3609 seq_printf(seq, ",gid=%u",
3610 from_kgid_munged(&init_user_ns, sbinfo->gid));
3613 * Showing inode{64,32} might be useful even if it's the system default,
3614 * since then people don't have to resort to checking both here and
3615 * /proc/config.gz to confirm 64-bit inums were successfully applied
3616 * (which may not even exist if IKCONFIG_PROC isn't enabled).
3618 * We hide it when inode64 isn't the default and we are using 32-bit
3619 * inodes, since that probably just means the feature isn't even under
3624 * +-----------------+-----------------+
3625 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
3626 * +------------------+-----------------+-----------------+
3627 * | full_inums=true | show | show |
3628 * | full_inums=false | show | hide |
3629 * +------------------+-----------------+-----------------+
3632 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
3633 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
3634 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3635 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3637 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3639 shmem_show_mpol(seq, sbinfo->mpol);
3643 #endif /* CONFIG_TMPFS */
3645 static void shmem_put_super(struct super_block *sb)
3647 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3649 free_percpu(sbinfo->ino_batch);
3650 percpu_counter_destroy(&sbinfo->used_blocks);
3651 mpol_put(sbinfo->mpol);
3653 sb->s_fs_info = NULL;
3656 static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
3658 struct shmem_options *ctx = fc->fs_private;
3659 struct inode *inode;
3660 struct shmem_sb_info *sbinfo;
3663 /* Round up to L1_CACHE_BYTES to resist false sharing */
3664 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3665 L1_CACHE_BYTES), GFP_KERNEL);
3669 sb->s_fs_info = sbinfo;
3673 * Per default we only allow half of the physical ram per
3674 * tmpfs instance, limiting inodes to one per page of lowmem;
3675 * but the internal instance is left unlimited.
3677 if (!(sb->s_flags & SB_KERNMOUNT)) {
3678 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
3679 ctx->blocks = shmem_default_max_blocks();
3680 if (!(ctx->seen & SHMEM_SEEN_INODES))
3681 ctx->inodes = shmem_default_max_inodes();
3682 if (!(ctx->seen & SHMEM_SEEN_INUMS))
3683 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
3685 sb->s_flags |= SB_NOUSER;
3687 sb->s_export_op = &shmem_export_ops;
3688 sb->s_flags |= SB_NOSEC;
3690 sb->s_flags |= SB_NOUSER;
3692 sbinfo->max_blocks = ctx->blocks;
3693 sbinfo->free_inodes = sbinfo->max_inodes = ctx->inodes;
3694 if (sb->s_flags & SB_KERNMOUNT) {
3695 sbinfo->ino_batch = alloc_percpu(ino_t);
3696 if (!sbinfo->ino_batch)
3699 sbinfo->uid = ctx->uid;
3700 sbinfo->gid = ctx->gid;
3701 sbinfo->full_inums = ctx->full_inums;
3702 sbinfo->mode = ctx->mode;
3703 sbinfo->huge = ctx->huge;
3704 sbinfo->mpol = ctx->mpol;
3707 spin_lock_init(&sbinfo->stat_lock);
3708 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3710 spin_lock_init(&sbinfo->shrinklist_lock);
3711 INIT_LIST_HEAD(&sbinfo->shrinklist);
3713 sb->s_maxbytes = MAX_LFS_FILESIZE;
3714 sb->s_blocksize = PAGE_SIZE;
3715 sb->s_blocksize_bits = PAGE_SHIFT;
3716 sb->s_magic = TMPFS_MAGIC;
3717 sb->s_op = &shmem_ops;
3718 sb->s_time_gran = 1;
3719 #ifdef CONFIG_TMPFS_XATTR
3720 sb->s_xattr = shmem_xattr_handlers;
3722 #ifdef CONFIG_TMPFS_POSIX_ACL
3723 sb->s_flags |= SB_POSIXACL;
3725 uuid_gen(&sb->s_uuid);
3727 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3730 inode->i_uid = sbinfo->uid;
3731 inode->i_gid = sbinfo->gid;
3732 sb->s_root = d_make_root(inode);
3738 shmem_put_super(sb);
3742 static int shmem_get_tree(struct fs_context *fc)
3744 return get_tree_nodev(fc, shmem_fill_super);
3747 static void shmem_free_fc(struct fs_context *fc)
3749 struct shmem_options *ctx = fc->fs_private;
3752 mpol_put(ctx->mpol);
3757 static const struct fs_context_operations shmem_fs_context_ops = {
3758 .free = shmem_free_fc,
3759 .get_tree = shmem_get_tree,
3761 .parse_monolithic = shmem_parse_options,
3762 .parse_param = shmem_parse_one,
3763 .reconfigure = shmem_reconfigure,
3767 static struct kmem_cache *shmem_inode_cachep;
3769 static struct inode *shmem_alloc_inode(struct super_block *sb)
3771 struct shmem_inode_info *info;
3772 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3775 return &info->vfs_inode;
3778 static void shmem_free_in_core_inode(struct inode *inode)
3780 if (S_ISLNK(inode->i_mode))
3781 kfree(inode->i_link);
3782 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3785 static void shmem_destroy_inode(struct inode *inode)
3787 if (S_ISREG(inode->i_mode))
3788 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3791 static void shmem_init_inode(void *foo)
3793 struct shmem_inode_info *info = foo;
3794 inode_init_once(&info->vfs_inode);
3797 static void shmem_init_inodecache(void)
3799 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3800 sizeof(struct shmem_inode_info),
3801 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3804 static void shmem_destroy_inodecache(void)
3806 kmem_cache_destroy(shmem_inode_cachep);
3809 const struct address_space_operations shmem_aops = {
3810 .writepage = shmem_writepage,
3811 .set_page_dirty = __set_page_dirty_no_writeback,
3813 .write_begin = shmem_write_begin,
3814 .write_end = shmem_write_end,
3816 #ifdef CONFIG_MIGRATION
3817 .migratepage = migrate_page,
3819 .error_remove_page = generic_error_remove_page,
3821 EXPORT_SYMBOL(shmem_aops);
3823 static const struct file_operations shmem_file_operations = {
3825 .get_unmapped_area = shmem_get_unmapped_area,
3827 .llseek = shmem_file_llseek,
3828 .read_iter = shmem_file_read_iter,
3829 .write_iter = generic_file_write_iter,
3830 .fsync = noop_fsync,
3831 .splice_read = generic_file_splice_read,
3832 .splice_write = iter_file_splice_write,
3833 .fallocate = shmem_fallocate,
3837 static const struct inode_operations shmem_inode_operations = {
3838 .getattr = shmem_getattr,
3839 .setattr = shmem_setattr,
3840 #ifdef CONFIG_TMPFS_XATTR
3841 .listxattr = shmem_listxattr,
3842 .set_acl = simple_set_acl,
3846 static const struct inode_operations shmem_dir_inode_operations = {
3848 .create = shmem_create,
3849 .lookup = simple_lookup,
3851 .unlink = shmem_unlink,
3852 .symlink = shmem_symlink,
3853 .mkdir = shmem_mkdir,
3854 .rmdir = shmem_rmdir,
3855 .mknod = shmem_mknod,
3856 .rename = shmem_rename2,
3857 .tmpfile = shmem_tmpfile,
3859 #ifdef CONFIG_TMPFS_XATTR
3860 .listxattr = shmem_listxattr,
3862 #ifdef CONFIG_TMPFS_POSIX_ACL
3863 .setattr = shmem_setattr,
3864 .set_acl = simple_set_acl,
3868 static const struct inode_operations shmem_special_inode_operations = {
3869 #ifdef CONFIG_TMPFS_XATTR
3870 .listxattr = shmem_listxattr,
3872 #ifdef CONFIG_TMPFS_POSIX_ACL
3873 .setattr = shmem_setattr,
3874 .set_acl = simple_set_acl,
3878 static const struct super_operations shmem_ops = {
3879 .alloc_inode = shmem_alloc_inode,
3880 .free_inode = shmem_free_in_core_inode,
3881 .destroy_inode = shmem_destroy_inode,
3883 .statfs = shmem_statfs,
3884 .show_options = shmem_show_options,
3886 .evict_inode = shmem_evict_inode,
3887 .drop_inode = generic_delete_inode,
3888 .put_super = shmem_put_super,
3889 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3890 .nr_cached_objects = shmem_unused_huge_count,
3891 .free_cached_objects = shmem_unused_huge_scan,
3895 static const struct vm_operations_struct shmem_vm_ops = {
3896 .fault = shmem_fault,
3897 .map_pages = filemap_map_pages,
3899 .set_policy = shmem_set_policy,
3900 .get_policy = shmem_get_policy,
3904 int shmem_init_fs_context(struct fs_context *fc)
3906 struct shmem_options *ctx;
3908 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
3912 ctx->mode = 0777 | S_ISVTX;
3913 ctx->uid = current_fsuid();
3914 ctx->gid = current_fsgid();
3916 fc->fs_private = ctx;
3917 fc->ops = &shmem_fs_context_ops;
3921 static struct file_system_type shmem_fs_type = {
3922 .owner = THIS_MODULE,
3924 .init_fs_context = shmem_init_fs_context,
3926 .parameters = shmem_fs_parameters,
3928 .kill_sb = kill_litter_super,
3929 .fs_flags = FS_USERNS_MOUNT | FS_THP_SUPPORT,
3932 int __init shmem_init(void)
3936 shmem_init_inodecache();
3938 error = register_filesystem(&shmem_fs_type);
3940 pr_err("Could not register tmpfs\n");
3944 shm_mnt = kern_mount(&shmem_fs_type);
3945 if (IS_ERR(shm_mnt)) {
3946 error = PTR_ERR(shm_mnt);
3947 pr_err("Could not kern_mount tmpfs\n");
3951 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3952 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
3953 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3955 shmem_huge = 0; /* just in case it was patched */
3960 unregister_filesystem(&shmem_fs_type);
3962 shmem_destroy_inodecache();
3963 shm_mnt = ERR_PTR(error);
3967 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
3968 static ssize_t shmem_enabled_show(struct kobject *kobj,
3969 struct kobj_attribute *attr, char *buf)
3971 static const int values[] = {
3973 SHMEM_HUGE_WITHIN_SIZE,
3982 for (i = 0; i < ARRAY_SIZE(values); i++) {
3983 len += sysfs_emit_at(buf, len,
3984 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
3986 shmem_format_huge(values[i]));
3989 len += sysfs_emit_at(buf, len, "\n");
3994 static ssize_t shmem_enabled_store(struct kobject *kobj,
3995 struct kobj_attribute *attr, const char *buf, size_t count)
4000 if (count + 1 > sizeof(tmp))
4002 memcpy(tmp, buf, count);
4004 if (count && tmp[count - 1] == '\n')
4005 tmp[count - 1] = '\0';
4007 huge = shmem_parse_huge(tmp);
4008 if (huge == -EINVAL)
4010 if (!has_transparent_hugepage() &&
4011 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4015 if (shmem_huge > SHMEM_HUGE_DENY)
4016 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4020 struct kobj_attribute shmem_enabled_attr =
4021 __ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
4022 #endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
4024 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
4025 bool shmem_huge_enabled(struct vm_area_struct *vma)
4027 struct inode *inode = file_inode(vma->vm_file);
4028 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
4032 if ((vma->vm_flags & VM_NOHUGEPAGE) ||
4033 test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
4035 if (shmem_huge == SHMEM_HUGE_FORCE)
4037 if (shmem_huge == SHMEM_HUGE_DENY)
4039 switch (sbinfo->huge) {
4040 case SHMEM_HUGE_NEVER:
4042 case SHMEM_HUGE_ALWAYS:
4044 case SHMEM_HUGE_WITHIN_SIZE:
4045 off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
4046 i_size = round_up(i_size_read(inode), PAGE_SIZE);
4047 if (i_size >= HPAGE_PMD_SIZE &&
4048 i_size >> PAGE_SHIFT >= off)
4051 case SHMEM_HUGE_ADVISE:
4052 /* TODO: implement fadvise() hints */
4053 return (vma->vm_flags & VM_HUGEPAGE);
4059 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4061 #else /* !CONFIG_SHMEM */
4064 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4066 * This is intended for small system where the benefits of the full
4067 * shmem code (swap-backed and resource-limited) are outweighed by
4068 * their complexity. On systems without swap this code should be
4069 * effectively equivalent, but much lighter weight.
4072 static struct file_system_type shmem_fs_type = {
4074 .init_fs_context = ramfs_init_fs_context,
4075 .parameters = ramfs_fs_parameters,
4076 .kill_sb = kill_litter_super,
4077 .fs_flags = FS_USERNS_MOUNT,
4080 int __init shmem_init(void)
4082 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4084 shm_mnt = kern_mount(&shmem_fs_type);
4085 BUG_ON(IS_ERR(shm_mnt));
4090 int shmem_unuse(unsigned int type, bool frontswap,
4091 unsigned long *fs_pages_to_unuse)
4096 int shmem_lock(struct file *file, int lock, struct user_struct *user)
4101 void shmem_unlock_mapping(struct address_space *mapping)
4106 unsigned long shmem_get_unmapped_area(struct file *file,
4107 unsigned long addr, unsigned long len,
4108 unsigned long pgoff, unsigned long flags)
4110 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4114 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4116 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4118 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4120 #define shmem_vm_ops generic_file_vm_ops
4121 #define shmem_file_operations ramfs_file_operations
4122 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4123 #define shmem_acct_size(flags, size) 0
4124 #define shmem_unacct_size(flags, size) do {} while (0)
4126 #endif /* CONFIG_SHMEM */
4130 static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4131 unsigned long flags, unsigned int i_flags)
4133 struct inode *inode;
4137 return ERR_CAST(mnt);
4139 if (size < 0 || size > MAX_LFS_FILESIZE)
4140 return ERR_PTR(-EINVAL);
4142 if (shmem_acct_size(flags, size))
4143 return ERR_PTR(-ENOMEM);
4145 inode = shmem_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0,
4147 if (unlikely(!inode)) {
4148 shmem_unacct_size(flags, size);
4149 return ERR_PTR(-ENOSPC);
4151 inode->i_flags |= i_flags;
4152 inode->i_size = size;
4153 clear_nlink(inode); /* It is unlinked */
4154 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4156 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
4157 &shmem_file_operations);
4164 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4165 * kernel internal. There will be NO LSM permission checks against the
4166 * underlying inode. So users of this interface must do LSM checks at a
4167 * higher layer. The users are the big_key and shm implementations. LSM
4168 * checks are provided at the key or shm level rather than the inode.
4169 * @name: name for dentry (to be seen in /proc/<pid>/maps
4170 * @size: size to be set for the file
4171 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4173 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4175 return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4179 * shmem_file_setup - get an unlinked file living in tmpfs
4180 * @name: name for dentry (to be seen in /proc/<pid>/maps
4181 * @size: size to be set for the file
4182 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4184 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4186 return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4188 EXPORT_SYMBOL_GPL(shmem_file_setup);
4191 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4192 * @mnt: the tmpfs mount where the file will be created
4193 * @name: name for dentry (to be seen in /proc/<pid>/maps
4194 * @size: size to be set for the file
4195 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4197 struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4198 loff_t size, unsigned long flags)
4200 return __shmem_file_setup(mnt, name, size, flags, 0);
4202 EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4205 * shmem_zero_setup - setup a shared anonymous mapping
4206 * @vma: the vma to be mmapped is prepared by do_mmap
4208 int shmem_zero_setup(struct vm_area_struct *vma)
4211 loff_t size = vma->vm_end - vma->vm_start;
4214 * Cloning a new file under mmap_lock leads to a lock ordering conflict
4215 * between XFS directory reading and selinux: since this file is only
4216 * accessible to the user through its mapping, use S_PRIVATE flag to
4217 * bypass file security, in the same way as shmem_kernel_file_setup().
4219 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4221 return PTR_ERR(file);
4225 vma->vm_file = file;
4226 vma->vm_ops = &shmem_vm_ops;
4228 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
4229 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4230 (vma->vm_end & HPAGE_PMD_MASK)) {
4231 khugepaged_enter(vma, vma->vm_flags);
4238 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4239 * @mapping: the page's address_space
4240 * @index: the page index
4241 * @gfp: the page allocator flags to use if allocating
4243 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4244 * with any new page allocations done using the specified allocation flags.
4245 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4246 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4247 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4249 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4250 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4252 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4253 pgoff_t index, gfp_t gfp)
4256 struct inode *inode = mapping->host;
4260 BUG_ON(!shmem_mapping(mapping));
4261 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4262 gfp, NULL, NULL, NULL);
4264 page = ERR_PTR(error);
4270 * The tiny !SHMEM case uses ramfs without swap
4272 return read_cache_page_gfp(mapping, index, gfp);
4275 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);