2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 * This file is released under the GPL.
24 #include <linux/init.h>
25 #include <linux/vfs.h>
26 #include <linux/mount.h>
27 #include <linux/pagemap.h>
28 #include <linux/file.h>
30 #include <linux/module.h>
31 #include <linux/percpu_counter.h>
32 #include <linux/swap.h>
34 static struct vfsmount *shm_mnt;
38 * This virtual memory filesystem is heavily based on the ramfs. It
39 * extends ramfs by the ability to use swap and honor resource limits
40 * which makes it a completely usable filesystem.
43 #include <linux/xattr.h>
44 #include <linux/exportfs.h>
45 #include <linux/posix_acl.h>
46 #include <linux/generic_acl.h>
47 #include <linux/mman.h>
48 #include <linux/string.h>
49 #include <linux/slab.h>
50 #include <linux/backing-dev.h>
51 #include <linux/shmem_fs.h>
52 #include <linux/writeback.h>
53 #include <linux/blkdev.h>
54 #include <linux/security.h>
55 #include <linux/swapops.h>
56 #include <linux/mempolicy.h>
57 #include <linux/namei.h>
58 #include <linux/ctype.h>
59 #include <linux/migrate.h>
60 #include <linux/highmem.h>
61 #include <linux/seq_file.h>
62 #include <linux/magic.h>
64 #include <asm/uaccess.h>
65 #include <asm/div64.h>
66 #include <asm/pgtable.h>
69 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
70 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
72 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
73 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
74 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
75 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
77 * We use / and * instead of shifts in the definitions below, so that the swap
78 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
80 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
81 #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
83 #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
84 #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
86 #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
87 #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
89 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
90 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
92 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
93 #define SHMEM_PAGEIN VM_READ
94 #define SHMEM_TRUNCATE VM_WRITE
96 /* Definition to limit shmem_truncate's steps between cond_rescheds */
97 #define LATENCY_LIMIT 64
99 /* Pretend that each entry is of this size in directory's i_size */
100 #define BOGO_DIRENT_SIZE 20
102 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
104 SGP_READ, /* don't exceed i_size, don't allocate page */
105 SGP_CACHE, /* don't exceed i_size, may allocate page */
106 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
107 SGP_WRITE, /* may exceed i_size, may allocate page */
111 static unsigned long shmem_default_max_blocks(void)
113 return totalram_pages / 2;
116 static unsigned long shmem_default_max_inodes(void)
118 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
122 static int shmem_getpage(struct inode *inode, unsigned long idx,
123 struct page **pagep, enum sgp_type sgp, int *type);
125 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
128 * The above definition of ENTRIES_PER_PAGE, and the use of
129 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
130 * might be reconsidered if it ever diverges from PAGE_SIZE.
132 * Mobility flags are masked out as swap vectors cannot move
134 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
135 PAGE_CACHE_SHIFT-PAGE_SHIFT);
138 static inline void shmem_dir_free(struct page *page)
140 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
143 static struct page **shmem_dir_map(struct page *page)
145 return (struct page **)kmap_atomic(page, KM_USER0);
148 static inline void shmem_dir_unmap(struct page **dir)
150 kunmap_atomic(dir, KM_USER0);
153 static swp_entry_t *shmem_swp_map(struct page *page)
155 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
158 static inline void shmem_swp_balance_unmap(void)
161 * When passing a pointer to an i_direct entry, to code which
162 * also handles indirect entries and so will shmem_swp_unmap,
163 * we must arrange for the preempt count to remain in balance.
164 * What kmap_atomic of a lowmem page does depends on config
165 * and architecture, so pretend to kmap_atomic some lowmem page.
167 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
170 static inline void shmem_swp_unmap(swp_entry_t *entry)
172 kunmap_atomic(entry, KM_USER1);
175 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
177 return sb->s_fs_info;
181 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
182 * for shared memory and for shared anonymous (/dev/zero) mappings
183 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
184 * consistent with the pre-accounting of private mappings ...
186 static inline int shmem_acct_size(unsigned long flags, loff_t size)
188 return (flags & VM_NORESERVE) ?
189 0 : security_vm_enough_memory_kern(VM_ACCT(size));
192 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
194 if (!(flags & VM_NORESERVE))
195 vm_unacct_memory(VM_ACCT(size));
199 * ... whereas tmpfs objects are accounted incrementally as
200 * pages are allocated, in order to allow huge sparse files.
201 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
202 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
204 static inline int shmem_acct_block(unsigned long flags)
206 return (flags & VM_NORESERVE) ?
207 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
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_CACHE_SIZE));
216 static const struct super_operations shmem_ops;
217 static const struct address_space_operations shmem_aops;
218 static const struct file_operations shmem_file_operations;
219 static const struct inode_operations shmem_inode_operations;
220 static const struct inode_operations shmem_dir_inode_operations;
221 static const struct inode_operations shmem_special_inode_operations;
222 static const struct vm_operations_struct shmem_vm_ops;
224 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
225 .ra_pages = 0, /* No readahead */
226 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
229 static LIST_HEAD(shmem_swaplist);
230 static DEFINE_MUTEX(shmem_swaplist_mutex);
232 static void shmem_free_blocks(struct inode *inode, long pages)
234 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
235 if (sbinfo->max_blocks) {
236 percpu_counter_add(&sbinfo->used_blocks, -pages);
237 spin_lock(&inode->i_lock);
238 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
239 spin_unlock(&inode->i_lock);
243 static int shmem_reserve_inode(struct super_block *sb)
245 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
246 if (sbinfo->max_inodes) {
247 spin_lock(&sbinfo->stat_lock);
248 if (!sbinfo->free_inodes) {
249 spin_unlock(&sbinfo->stat_lock);
252 sbinfo->free_inodes--;
253 spin_unlock(&sbinfo->stat_lock);
258 static void shmem_free_inode(struct super_block *sb)
260 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
261 if (sbinfo->max_inodes) {
262 spin_lock(&sbinfo->stat_lock);
263 sbinfo->free_inodes++;
264 spin_unlock(&sbinfo->stat_lock);
269 * shmem_recalc_inode - recalculate the size of an inode
270 * @inode: inode to recalc
272 * We have to calculate the free blocks since the mm can drop
273 * undirtied hole pages behind our back.
275 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
276 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
278 * It has to be called with the spinlock held.
280 static void shmem_recalc_inode(struct inode *inode)
282 struct shmem_inode_info *info = SHMEM_I(inode);
285 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
287 info->alloced -= freed;
288 shmem_unacct_blocks(info->flags, freed);
289 shmem_free_blocks(inode, freed);
294 * shmem_swp_entry - find the swap vector position in the info structure
295 * @info: info structure for the inode
296 * @index: index of the page to find
297 * @page: optional page to add to the structure. Has to be preset to
300 * If there is no space allocated yet it will return NULL when
301 * page is NULL, else it will use the page for the needed block,
302 * setting it to NULL on return to indicate that it has been used.
304 * The swap vector is organized the following way:
306 * There are SHMEM_NR_DIRECT entries directly stored in the
307 * shmem_inode_info structure. So small files do not need an addional
310 * For pages with index > SHMEM_NR_DIRECT there is the pointer
311 * i_indirect which points to a page which holds in the first half
312 * doubly indirect blocks, in the second half triple indirect blocks:
314 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
315 * following layout (for SHMEM_NR_DIRECT == 16):
317 * i_indirect -> dir --> 16-19
330 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
332 unsigned long offset;
336 if (index < SHMEM_NR_DIRECT) {
337 shmem_swp_balance_unmap();
338 return info->i_direct+index;
340 if (!info->i_indirect) {
342 info->i_indirect = *page;
345 return NULL; /* need another page */
348 index -= SHMEM_NR_DIRECT;
349 offset = index % ENTRIES_PER_PAGE;
350 index /= ENTRIES_PER_PAGE;
351 dir = shmem_dir_map(info->i_indirect);
353 if (index >= ENTRIES_PER_PAGE/2) {
354 index -= ENTRIES_PER_PAGE/2;
355 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
356 index %= ENTRIES_PER_PAGE;
363 shmem_dir_unmap(dir);
364 return NULL; /* need another page */
366 shmem_dir_unmap(dir);
367 dir = shmem_dir_map(subdir);
373 if (!page || !(subdir = *page)) {
374 shmem_dir_unmap(dir);
375 return NULL; /* need a page */
380 shmem_dir_unmap(dir);
381 return shmem_swp_map(subdir) + offset;
384 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
386 long incdec = value? 1: -1;
389 info->swapped += incdec;
390 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
391 struct page *page = kmap_atomic_to_page(entry);
392 set_page_private(page, page_private(page) + incdec);
397 * shmem_swp_alloc - get the position of the swap entry for the page.
398 * @info: info structure for the inode
399 * @index: index of the page to find
400 * @sgp: check and recheck i_size? skip allocation?
402 * If the entry does not exist, allocate it.
404 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
406 struct inode *inode = &info->vfs_inode;
407 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
408 struct page *page = NULL;
411 if (sgp != SGP_WRITE &&
412 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
413 return ERR_PTR(-EINVAL);
415 while (!(entry = shmem_swp_entry(info, index, &page))) {
417 return shmem_swp_map(ZERO_PAGE(0));
419 * Test used_blocks against 1 less max_blocks, since we have 1 data
420 * page (and perhaps indirect index pages) yet to allocate:
421 * a waste to allocate index if we cannot allocate data.
423 if (sbinfo->max_blocks) {
424 if (percpu_counter_compare(&sbinfo->used_blocks,
425 sbinfo->max_blocks - 1) >= 0)
426 return ERR_PTR(-ENOSPC);
427 percpu_counter_inc(&sbinfo->used_blocks);
428 spin_lock(&inode->i_lock);
429 inode->i_blocks += BLOCKS_PER_PAGE;
430 spin_unlock(&inode->i_lock);
433 spin_unlock(&info->lock);
434 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
435 spin_lock(&info->lock);
438 shmem_free_blocks(inode, 1);
439 return ERR_PTR(-ENOMEM);
441 if (sgp != SGP_WRITE &&
442 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
443 entry = ERR_PTR(-EINVAL);
446 if (info->next_index <= index)
447 info->next_index = index + 1;
450 /* another task gave its page, or truncated the file */
451 shmem_free_blocks(inode, 1);
452 shmem_dir_free(page);
454 if (info->next_index <= index && !IS_ERR(entry))
455 info->next_index = index + 1;
460 * shmem_free_swp - free some swap entries in a directory
461 * @dir: pointer to the directory
462 * @edir: pointer after last entry of the directory
463 * @punch_lock: pointer to spinlock when needed for the holepunch case
465 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
466 spinlock_t *punch_lock)
468 spinlock_t *punch_unlock = NULL;
472 for (ptr = dir; ptr < edir; ptr++) {
474 if (unlikely(punch_lock)) {
475 punch_unlock = punch_lock;
477 spin_lock(punch_unlock);
481 free_swap_and_cache(*ptr);
482 *ptr = (swp_entry_t){0};
487 spin_unlock(punch_unlock);
491 static int shmem_map_and_free_swp(struct page *subdir, int offset,
492 int limit, struct page ***dir, spinlock_t *punch_lock)
497 ptr = shmem_swp_map(subdir);
498 for (; offset < limit; offset += LATENCY_LIMIT) {
499 int size = limit - offset;
500 if (size > LATENCY_LIMIT)
501 size = LATENCY_LIMIT;
502 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
504 if (need_resched()) {
505 shmem_swp_unmap(ptr);
507 shmem_dir_unmap(*dir);
511 ptr = shmem_swp_map(subdir);
514 shmem_swp_unmap(ptr);
518 static void shmem_free_pages(struct list_head *next)
524 page = container_of(next, struct page, lru);
526 shmem_dir_free(page);
528 if (freed >= LATENCY_LIMIT) {
535 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
537 struct shmem_inode_info *info = SHMEM_I(inode);
542 unsigned long diroff;
548 LIST_HEAD(pages_to_free);
549 long nr_pages_to_free = 0;
550 long nr_swaps_freed = 0;
554 spinlock_t *needs_lock;
555 spinlock_t *punch_lock;
556 unsigned long upper_limit;
558 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
559 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
560 if (idx >= info->next_index)
563 spin_lock(&info->lock);
564 info->flags |= SHMEM_TRUNCATE;
565 if (likely(end == (loff_t) -1)) {
566 limit = info->next_index;
567 upper_limit = SHMEM_MAX_INDEX;
568 info->next_index = idx;
572 if (end + 1 >= inode->i_size) { /* we may free a little more */
573 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
575 upper_limit = SHMEM_MAX_INDEX;
577 limit = (end + 1) >> PAGE_CACHE_SHIFT;
580 needs_lock = &info->lock;
584 topdir = info->i_indirect;
585 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
586 info->i_indirect = NULL;
588 list_add(&topdir->lru, &pages_to_free);
590 spin_unlock(&info->lock);
592 if (info->swapped && idx < SHMEM_NR_DIRECT) {
593 ptr = info->i_direct;
595 if (size > SHMEM_NR_DIRECT)
596 size = SHMEM_NR_DIRECT;
597 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
601 * If there are no indirect blocks or we are punching a hole
602 * below indirect blocks, nothing to be done.
604 if (!topdir || limit <= SHMEM_NR_DIRECT)
608 * The truncation case has already dropped info->lock, and we're safe
609 * because i_size and next_index have already been lowered, preventing
610 * access beyond. But in the punch_hole case, we still need to take
611 * the lock when updating the swap directory, because there might be
612 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
613 * shmem_writepage. However, whenever we find we can remove a whole
614 * directory page (not at the misaligned start or end of the range),
615 * we first NULLify its pointer in the level above, and then have no
616 * need to take the lock when updating its contents: needs_lock and
617 * punch_lock (either pointing to info->lock or NULL) manage this.
620 upper_limit -= SHMEM_NR_DIRECT;
621 limit -= SHMEM_NR_DIRECT;
622 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
623 offset = idx % ENTRIES_PER_PAGE;
626 dir = shmem_dir_map(topdir);
627 stage = ENTRIES_PER_PAGEPAGE/2;
628 if (idx < ENTRIES_PER_PAGEPAGE/2) {
630 diroff = idx/ENTRIES_PER_PAGE;
632 dir += ENTRIES_PER_PAGE/2;
633 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
635 stage += ENTRIES_PER_PAGEPAGE;
638 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
639 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
640 if (!diroff && !offset && upper_limit >= stage) {
642 spin_lock(needs_lock);
644 spin_unlock(needs_lock);
649 list_add(&middir->lru, &pages_to_free);
651 shmem_dir_unmap(dir);
652 dir = shmem_dir_map(middir);
660 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
661 if (unlikely(idx == stage)) {
662 shmem_dir_unmap(dir);
663 dir = shmem_dir_map(topdir) +
664 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
667 idx += ENTRIES_PER_PAGEPAGE;
671 stage = idx + ENTRIES_PER_PAGEPAGE;
674 needs_lock = &info->lock;
675 if (upper_limit >= stage) {
677 spin_lock(needs_lock);
679 spin_unlock(needs_lock);
684 list_add(&middir->lru, &pages_to_free);
686 shmem_dir_unmap(dir);
688 dir = shmem_dir_map(middir);
691 punch_lock = needs_lock;
692 subdir = dir[diroff];
693 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
695 spin_lock(needs_lock);
697 spin_unlock(needs_lock);
702 list_add(&subdir->lru, &pages_to_free);
704 if (subdir && page_private(subdir) /* has swap entries */) {
706 if (size > ENTRIES_PER_PAGE)
707 size = ENTRIES_PER_PAGE;
708 freed = shmem_map_and_free_swp(subdir,
709 offset, size, &dir, punch_lock);
711 dir = shmem_dir_map(middir);
712 nr_swaps_freed += freed;
713 if (offset || punch_lock) {
714 spin_lock(&info->lock);
715 set_page_private(subdir,
716 page_private(subdir) - freed);
717 spin_unlock(&info->lock);
719 BUG_ON(page_private(subdir) != freed);
724 shmem_dir_unmap(dir);
726 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
728 * Call truncate_inode_pages again: racing shmem_unuse_inode
729 * may have swizzled a page in from swap since
730 * truncate_pagecache or generic_delete_inode did it, before we
731 * lowered next_index. Also, though shmem_getpage checks
732 * i_size before adding to cache, no recheck after: so fix the
733 * narrow window there too.
735 * Recalling truncate_inode_pages_range and unmap_mapping_range
736 * every time for punch_hole (which never got a chance to clear
737 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
738 * yet hardly ever necessary: try to optimize them out later.
740 truncate_inode_pages_range(inode->i_mapping, start, end);
742 unmap_mapping_range(inode->i_mapping, start,
746 spin_lock(&info->lock);
747 info->flags &= ~SHMEM_TRUNCATE;
748 info->swapped -= nr_swaps_freed;
749 if (nr_pages_to_free)
750 shmem_free_blocks(inode, nr_pages_to_free);
751 shmem_recalc_inode(inode);
752 spin_unlock(&info->lock);
755 * Empty swap vector directory pages to be freed?
757 if (!list_empty(&pages_to_free)) {
758 pages_to_free.prev->next = NULL;
759 shmem_free_pages(pages_to_free.next);
763 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
765 struct inode *inode = dentry->d_inode;
766 loff_t newsize = attr->ia_size;
769 error = inode_change_ok(inode, attr);
773 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)
774 && newsize != inode->i_size) {
775 struct page *page = NULL;
777 if (newsize < inode->i_size) {
779 * If truncating down to a partial page, then
780 * if that page is already allocated, hold it
781 * in memory until the truncation is over, so
782 * truncate_partial_page cannot miss it were
783 * it assigned to swap.
785 if (newsize & (PAGE_CACHE_SIZE-1)) {
786 (void) shmem_getpage(inode,
787 newsize >> PAGE_CACHE_SHIFT,
788 &page, SGP_READ, NULL);
793 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
794 * detect if any pages might have been added to cache
795 * after truncate_inode_pages. But we needn't bother
796 * if it's being fully truncated to zero-length: the
797 * nrpages check is efficient enough in that case.
800 struct shmem_inode_info *info = SHMEM_I(inode);
801 spin_lock(&info->lock);
802 info->flags &= ~SHMEM_PAGEIN;
803 spin_unlock(&info->lock);
807 /* XXX(truncate): truncate_setsize should be called last */
808 truncate_setsize(inode, newsize);
810 page_cache_release(page);
811 shmem_truncate_range(inode, newsize, (loff_t)-1);
814 setattr_copy(inode, attr);
815 #ifdef CONFIG_TMPFS_POSIX_ACL
816 if (attr->ia_valid & ATTR_MODE)
817 error = generic_acl_chmod(inode);
822 static void shmem_evict_inode(struct inode *inode)
824 struct shmem_inode_info *info = SHMEM_I(inode);
826 if (inode->i_mapping->a_ops == &shmem_aops) {
827 truncate_inode_pages(inode->i_mapping, 0);
828 shmem_unacct_size(info->flags, inode->i_size);
830 shmem_truncate_range(inode, 0, (loff_t)-1);
831 if (!list_empty(&info->swaplist)) {
832 mutex_lock(&shmem_swaplist_mutex);
833 list_del_init(&info->swaplist);
834 mutex_unlock(&shmem_swaplist_mutex);
837 BUG_ON(inode->i_blocks);
838 shmem_free_inode(inode->i_sb);
839 end_writeback(inode);
842 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
846 for (ptr = dir; ptr < edir; ptr++) {
847 if (ptr->val == entry.val)
853 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
855 struct address_space *mapping;
867 ptr = info->i_direct;
868 spin_lock(&info->lock);
869 if (!info->swapped) {
870 list_del_init(&info->swaplist);
873 limit = info->next_index;
875 if (size > SHMEM_NR_DIRECT)
876 size = SHMEM_NR_DIRECT;
877 offset = shmem_find_swp(entry, ptr, ptr+size);
879 shmem_swp_balance_unmap();
882 if (!info->i_indirect)
885 dir = shmem_dir_map(info->i_indirect);
886 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
888 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
889 if (unlikely(idx == stage)) {
890 shmem_dir_unmap(dir-1);
891 if (cond_resched_lock(&info->lock)) {
892 /* check it has not been truncated */
893 if (limit > info->next_index) {
894 limit = info->next_index;
899 dir = shmem_dir_map(info->i_indirect) +
900 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
903 idx += ENTRIES_PER_PAGEPAGE;
907 stage = idx + ENTRIES_PER_PAGEPAGE;
909 shmem_dir_unmap(dir);
910 dir = shmem_dir_map(subdir);
913 if (subdir && page_private(subdir)) {
914 ptr = shmem_swp_map(subdir);
916 if (size > ENTRIES_PER_PAGE)
917 size = ENTRIES_PER_PAGE;
918 offset = shmem_find_swp(entry, ptr, ptr+size);
920 shmem_dir_unmap(dir);
923 shmem_swp_unmap(ptr);
927 shmem_dir_unmap(dir-1);
929 spin_unlock(&info->lock);
936 * Move _head_ to start search for next from here.
937 * But be careful: shmem_evict_inode checks list_empty without taking
938 * mutex, and there's an instant in list_move_tail when info->swaplist
939 * would appear empty, if it were the only one on shmem_swaplist. We
940 * could avoid doing it if inode NULL; or use this minor optimization.
942 if (shmem_swaplist.next != &info->swaplist)
943 list_move_tail(&shmem_swaplist, &info->swaplist);
946 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
947 * but also to hold up shmem_evict_inode(): so inode cannot be freed
948 * beneath us (pagelock doesn't help until the page is in pagecache).
950 mapping = info->vfs_inode.i_mapping;
951 error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT);
952 /* which does mem_cgroup_uncharge_cache_page on error */
954 if (error == -EEXIST) {
955 struct page *filepage = find_get_page(mapping, idx);
959 * There might be a more uptodate page coming down
960 * from a stacked writepage: forget our swappage if so.
962 if (PageUptodate(filepage))
964 page_cache_release(filepage);
968 delete_from_swap_cache(page);
969 set_page_dirty(page);
970 info->flags |= SHMEM_PAGEIN;
971 shmem_swp_set(info, ptr, 0);
973 error = 1; /* not an error, but entry was found */
975 shmem_swp_unmap(ptr);
976 spin_unlock(&info->lock);
981 * shmem_unuse() search for an eventually swapped out shmem page.
983 int shmem_unuse(swp_entry_t entry, struct page *page)
985 struct list_head *p, *next;
986 struct shmem_inode_info *info;
991 * Charge page using GFP_KERNEL while we can wait, before taking
992 * the shmem_swaplist_mutex which might hold up shmem_writepage().
993 * Charged back to the user (not to caller) when swap account is used.
994 * add_to_page_cache() will be called with GFP_NOWAIT.
996 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
1000 * Try to preload while we can wait, to not make a habit of
1001 * draining atomic reserves; but don't latch on to this cpu,
1002 * it's okay if sometimes we get rescheduled after this.
1004 error = radix_tree_preload(GFP_KERNEL);
1007 radix_tree_preload_end();
1009 mutex_lock(&shmem_swaplist_mutex);
1010 list_for_each_safe(p, next, &shmem_swaplist) {
1011 info = list_entry(p, struct shmem_inode_info, swaplist);
1012 found = shmem_unuse_inode(info, entry, page);
1017 mutex_unlock(&shmem_swaplist_mutex);
1021 mem_cgroup_uncharge_cache_page(page);
1026 page_cache_release(page);
1031 * Move the page from the page cache to the swap cache.
1033 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1035 struct shmem_inode_info *info;
1036 swp_entry_t *entry, swap;
1037 struct address_space *mapping;
1038 unsigned long index;
1039 struct inode *inode;
1040 bool unlock_mutex = false;
1042 BUG_ON(!PageLocked(page));
1043 mapping = page->mapping;
1044 index = page->index;
1045 inode = mapping->host;
1046 info = SHMEM_I(inode);
1047 if (info->flags & VM_LOCKED)
1049 if (!total_swap_pages)
1053 * shmem_backing_dev_info's capabilities prevent regular writeback or
1054 * sync from ever calling shmem_writepage; but a stacking filesystem
1055 * may use the ->writepage of its underlying filesystem, in which case
1056 * tmpfs should write out to swap only in response to memory pressure,
1057 * and not for the writeback threads or sync. However, in those cases,
1058 * we do still want to check if there's a redundant swappage to be
1061 if (wbc->for_reclaim)
1062 swap = get_swap_page();
1067 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1068 * if it's not already there. Do it now because we cannot take
1069 * mutex while holding spinlock, and must do so before the page
1070 * is moved to swap cache, when its pagelock no longer protects
1071 * the inode from eviction. But don't unlock the mutex until
1072 * we've taken the spinlock, because shmem_unuse_inode() will
1073 * prune a !swapped inode from the swaplist under both locks.
1075 if (swap.val && list_empty(&info->swaplist)) {
1076 mutex_lock(&shmem_swaplist_mutex);
1077 /* move instead of add in case we're racing */
1078 list_move_tail(&info->swaplist, &shmem_swaplist);
1079 unlock_mutex = true;
1082 spin_lock(&info->lock);
1084 mutex_unlock(&shmem_swaplist_mutex);
1086 if (index >= info->next_index) {
1087 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1090 entry = shmem_swp_entry(info, index, NULL);
1093 * The more uptodate page coming down from a stacked
1094 * writepage should replace our old swappage.
1096 free_swap_and_cache(*entry);
1097 shmem_swp_set(info, entry, 0);
1099 shmem_recalc_inode(inode);
1101 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1102 delete_from_page_cache(page);
1103 shmem_swp_set(info, entry, swap.val);
1104 shmem_swp_unmap(entry);
1105 spin_unlock(&info->lock);
1106 swap_shmem_alloc(swap);
1107 BUG_ON(page_mapped(page));
1108 swap_writepage(page, wbc);
1112 shmem_swp_unmap(entry);
1114 spin_unlock(&info->lock);
1116 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1117 * clear SWAP_HAS_CACHE flag.
1119 swapcache_free(swap, NULL);
1121 set_page_dirty(page);
1122 if (wbc->for_reclaim)
1123 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1130 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1134 if (!mpol || mpol->mode == MPOL_DEFAULT)
1135 return; /* show nothing */
1137 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
1139 seq_printf(seq, ",mpol=%s", buffer);
1142 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1144 struct mempolicy *mpol = NULL;
1146 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1147 mpol = sbinfo->mpol;
1149 spin_unlock(&sbinfo->stat_lock);
1153 #endif /* CONFIG_TMPFS */
1155 static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1156 struct shmem_inode_info *info, unsigned long idx)
1158 struct mempolicy mpol, *spol;
1159 struct vm_area_struct pvma;
1162 spol = mpol_cond_copy(&mpol,
1163 mpol_shared_policy_lookup(&info->policy, idx));
1165 /* Create a pseudo vma that just contains the policy */
1167 pvma.vm_pgoff = idx;
1169 pvma.vm_policy = spol;
1170 page = swapin_readahead(entry, gfp, &pvma, 0);
1174 static struct page *shmem_alloc_page(gfp_t gfp,
1175 struct shmem_inode_info *info, unsigned long idx)
1177 struct vm_area_struct pvma;
1179 /* Create a pseudo vma that just contains the policy */
1181 pvma.vm_pgoff = idx;
1183 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1186 * alloc_page_vma() will drop the shared policy reference
1188 return alloc_page_vma(gfp, &pvma, 0);
1190 #else /* !CONFIG_NUMA */
1192 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
1195 #endif /* CONFIG_TMPFS */
1197 static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1198 struct shmem_inode_info *info, unsigned long idx)
1200 return swapin_readahead(entry, gfp, NULL, 0);
1203 static inline struct page *shmem_alloc_page(gfp_t gfp,
1204 struct shmem_inode_info *info, unsigned long idx)
1206 return alloc_page(gfp);
1208 #endif /* CONFIG_NUMA */
1210 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1211 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1218 * shmem_getpage - either get the page from swap or allocate a new one
1220 * If we allocate a new one we do not mark it dirty. That's up to the
1221 * vm. If we swap it in we mark it dirty since we also free the swap
1222 * entry since a page cannot live in both the swap and page cache
1224 static int shmem_getpage(struct inode *inode, unsigned long idx,
1225 struct page **pagep, enum sgp_type sgp, int *type)
1227 struct address_space *mapping = inode->i_mapping;
1228 struct shmem_inode_info *info = SHMEM_I(inode);
1229 struct shmem_sb_info *sbinfo;
1230 struct page *filepage = *pagep;
1231 struct page *swappage;
1232 struct page *prealloc_page = NULL;
1238 if (idx >= SHMEM_MAX_INDEX)
1245 * Normally, filepage is NULL on entry, and either found
1246 * uptodate immediately, or allocated and zeroed, or read
1247 * in under swappage, which is then assigned to filepage.
1248 * But shmem_readpage (required for splice) passes in a locked
1249 * filepage, which may be found not uptodate by other callers
1250 * too, and may need to be copied from the swappage read in.
1254 filepage = find_lock_page(mapping, idx);
1255 if (filepage && PageUptodate(filepage))
1257 gfp = mapping_gfp_mask(mapping);
1260 * Try to preload while we can wait, to not make a habit of
1261 * draining atomic reserves; but don't latch on to this cpu.
1263 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1266 radix_tree_preload_end();
1267 if (sgp != SGP_READ && !prealloc_page) {
1268 /* We don't care if this fails */
1269 prealloc_page = shmem_alloc_page(gfp, info, idx);
1270 if (prealloc_page) {
1271 if (mem_cgroup_cache_charge(prealloc_page,
1272 current->mm, GFP_KERNEL)) {
1273 page_cache_release(prealloc_page);
1274 prealloc_page = NULL;
1281 spin_lock(&info->lock);
1282 shmem_recalc_inode(inode);
1283 entry = shmem_swp_alloc(info, idx, sgp);
1284 if (IS_ERR(entry)) {
1285 spin_unlock(&info->lock);
1286 error = PTR_ERR(entry);
1292 /* Look it up and read it in.. */
1293 swappage = lookup_swap_cache(swap);
1295 shmem_swp_unmap(entry);
1296 /* here we actually do the io */
1297 if (type && !(*type & VM_FAULT_MAJOR)) {
1298 __count_vm_event(PGMAJFAULT);
1299 *type |= VM_FAULT_MAJOR;
1301 spin_unlock(&info->lock);
1302 swappage = shmem_swapin(swap, gfp, info, idx);
1304 spin_lock(&info->lock);
1305 entry = shmem_swp_alloc(info, idx, sgp);
1307 error = PTR_ERR(entry);
1309 if (entry->val == swap.val)
1311 shmem_swp_unmap(entry);
1313 spin_unlock(&info->lock);
1318 wait_on_page_locked(swappage);
1319 page_cache_release(swappage);
1323 /* We have to do this with page locked to prevent races */
1324 if (!trylock_page(swappage)) {
1325 shmem_swp_unmap(entry);
1326 spin_unlock(&info->lock);
1327 wait_on_page_locked(swappage);
1328 page_cache_release(swappage);
1331 if (PageWriteback(swappage)) {
1332 shmem_swp_unmap(entry);
1333 spin_unlock(&info->lock);
1334 wait_on_page_writeback(swappage);
1335 unlock_page(swappage);
1336 page_cache_release(swappage);
1339 if (!PageUptodate(swappage)) {
1340 shmem_swp_unmap(entry);
1341 spin_unlock(&info->lock);
1342 unlock_page(swappage);
1343 page_cache_release(swappage);
1349 shmem_swp_set(info, entry, 0);
1350 shmem_swp_unmap(entry);
1351 delete_from_swap_cache(swappage);
1352 spin_unlock(&info->lock);
1353 copy_highpage(filepage, swappage);
1354 unlock_page(swappage);
1355 page_cache_release(swappage);
1356 flush_dcache_page(filepage);
1357 SetPageUptodate(filepage);
1358 set_page_dirty(filepage);
1360 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1361 idx, GFP_NOWAIT))) {
1362 info->flags |= SHMEM_PAGEIN;
1363 shmem_swp_set(info, entry, 0);
1364 shmem_swp_unmap(entry);
1365 delete_from_swap_cache(swappage);
1366 spin_unlock(&info->lock);
1367 filepage = swappage;
1368 set_page_dirty(filepage);
1371 shmem_swp_unmap(entry);
1372 spin_unlock(&info->lock);
1373 if (error == -ENOMEM) {
1375 * reclaim from proper memory cgroup and
1376 * call memcg's OOM if needed.
1378 error = mem_cgroup_shmem_charge_fallback(
1383 unlock_page(swappage);
1384 page_cache_release(swappage);
1388 unlock_page(swappage);
1389 page_cache_release(swappage);
1392 } else if (sgp == SGP_READ && !filepage) {
1393 shmem_swp_unmap(entry);
1394 filepage = find_get_page(mapping, idx);
1396 (!PageUptodate(filepage) || !trylock_page(filepage))) {
1397 spin_unlock(&info->lock);
1398 wait_on_page_locked(filepage);
1399 page_cache_release(filepage);
1403 spin_unlock(&info->lock);
1405 shmem_swp_unmap(entry);
1406 sbinfo = SHMEM_SB(inode->i_sb);
1407 if (sbinfo->max_blocks) {
1408 if (percpu_counter_compare(&sbinfo->used_blocks,
1409 sbinfo->max_blocks) >= 0 ||
1410 shmem_acct_block(info->flags)) {
1411 spin_unlock(&info->lock);
1415 percpu_counter_inc(&sbinfo->used_blocks);
1416 spin_lock(&inode->i_lock);
1417 inode->i_blocks += BLOCKS_PER_PAGE;
1418 spin_unlock(&inode->i_lock);
1419 } else if (shmem_acct_block(info->flags)) {
1420 spin_unlock(&info->lock);
1428 if (!prealloc_page) {
1429 spin_unlock(&info->lock);
1430 filepage = shmem_alloc_page(gfp, info, idx);
1432 shmem_unacct_blocks(info->flags, 1);
1433 shmem_free_blocks(inode, 1);
1437 SetPageSwapBacked(filepage);
1440 * Precharge page while we can wait, compensate
1443 error = mem_cgroup_cache_charge(filepage,
1444 current->mm, GFP_KERNEL);
1446 page_cache_release(filepage);
1447 shmem_unacct_blocks(info->flags, 1);
1448 shmem_free_blocks(inode, 1);
1453 spin_lock(&info->lock);
1455 filepage = prealloc_page;
1456 prealloc_page = NULL;
1457 SetPageSwapBacked(filepage);
1460 entry = shmem_swp_alloc(info, idx, sgp);
1462 error = PTR_ERR(entry);
1465 shmem_swp_unmap(entry);
1467 ret = error || swap.val;
1469 mem_cgroup_uncharge_cache_page(filepage);
1471 ret = add_to_page_cache_lru(filepage, mapping,
1474 * At add_to_page_cache_lru() failure, uncharge will
1475 * be done automatically.
1478 spin_unlock(&info->lock);
1479 page_cache_release(filepage);
1480 shmem_unacct_blocks(info->flags, 1);
1481 shmem_free_blocks(inode, 1);
1487 info->flags |= SHMEM_PAGEIN;
1491 spin_unlock(&info->lock);
1492 clear_highpage(filepage);
1493 flush_dcache_page(filepage);
1494 SetPageUptodate(filepage);
1495 if (sgp == SGP_DIRTY)
1496 set_page_dirty(filepage);
1504 if (*pagep != filepage) {
1505 unlock_page(filepage);
1506 page_cache_release(filepage);
1509 if (prealloc_page) {
1510 mem_cgroup_uncharge_cache_page(prealloc_page);
1511 page_cache_release(prealloc_page);
1516 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1518 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1522 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1523 return VM_FAULT_SIGBUS;
1525 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1527 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1529 return ret | VM_FAULT_LOCKED;
1533 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1535 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1536 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1539 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1542 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1545 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1546 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1550 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1552 struct inode *inode = file->f_path.dentry->d_inode;
1553 struct shmem_inode_info *info = SHMEM_I(inode);
1554 int retval = -ENOMEM;
1556 spin_lock(&info->lock);
1557 if (lock && !(info->flags & VM_LOCKED)) {
1558 if (!user_shm_lock(inode->i_size, user))
1560 info->flags |= VM_LOCKED;
1561 mapping_set_unevictable(file->f_mapping);
1563 if (!lock && (info->flags & VM_LOCKED) && user) {
1564 user_shm_unlock(inode->i_size, user);
1565 info->flags &= ~VM_LOCKED;
1566 mapping_clear_unevictable(file->f_mapping);
1567 scan_mapping_unevictable_pages(file->f_mapping);
1572 spin_unlock(&info->lock);
1576 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1578 file_accessed(file);
1579 vma->vm_ops = &shmem_vm_ops;
1580 vma->vm_flags |= VM_CAN_NONLINEAR;
1584 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1585 int mode, dev_t dev, unsigned long flags)
1587 struct inode *inode;
1588 struct shmem_inode_info *info;
1589 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1591 if (shmem_reserve_inode(sb))
1594 inode = new_inode(sb);
1596 inode->i_ino = get_next_ino();
1597 inode_init_owner(inode, dir, mode);
1598 inode->i_blocks = 0;
1599 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1600 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1601 inode->i_generation = get_seconds();
1602 info = SHMEM_I(inode);
1603 memset(info, 0, (char *)inode - (char *)info);
1604 spin_lock_init(&info->lock);
1605 info->flags = flags & VM_NORESERVE;
1606 INIT_LIST_HEAD(&info->swaplist);
1607 cache_no_acl(inode);
1609 switch (mode & S_IFMT) {
1611 inode->i_op = &shmem_special_inode_operations;
1612 init_special_inode(inode, mode, dev);
1615 inode->i_mapping->a_ops = &shmem_aops;
1616 inode->i_op = &shmem_inode_operations;
1617 inode->i_fop = &shmem_file_operations;
1618 mpol_shared_policy_init(&info->policy,
1619 shmem_get_sbmpol(sbinfo));
1623 /* Some things misbehave if size == 0 on a directory */
1624 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1625 inode->i_op = &shmem_dir_inode_operations;
1626 inode->i_fop = &simple_dir_operations;
1630 * Must not load anything in the rbtree,
1631 * mpol_free_shared_policy will not be called.
1633 mpol_shared_policy_init(&info->policy, NULL);
1637 shmem_free_inode(sb);
1642 static const struct inode_operations shmem_symlink_inode_operations;
1643 static const struct inode_operations shmem_symlink_inline_operations;
1646 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1647 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1648 * below the loop driver, in the generic fashion that many filesystems support.
1650 static int shmem_readpage(struct file *file, struct page *page)
1652 struct inode *inode = page->mapping->host;
1653 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1659 shmem_write_begin(struct file *file, struct address_space *mapping,
1660 loff_t pos, unsigned len, unsigned flags,
1661 struct page **pagep, void **fsdata)
1663 struct inode *inode = mapping->host;
1664 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1666 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1670 shmem_write_end(struct file *file, struct address_space *mapping,
1671 loff_t pos, unsigned len, unsigned copied,
1672 struct page *page, void *fsdata)
1674 struct inode *inode = mapping->host;
1676 if (pos + copied > inode->i_size)
1677 i_size_write(inode, pos + copied);
1679 set_page_dirty(page);
1681 page_cache_release(page);
1686 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1688 struct inode *inode = filp->f_path.dentry->d_inode;
1689 struct address_space *mapping = inode->i_mapping;
1690 unsigned long index, offset;
1691 enum sgp_type sgp = SGP_READ;
1694 * Might this read be for a stacking filesystem? Then when reading
1695 * holes of a sparse file, we actually need to allocate those pages,
1696 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1698 if (segment_eq(get_fs(), KERNEL_DS))
1701 index = *ppos >> PAGE_CACHE_SHIFT;
1702 offset = *ppos & ~PAGE_CACHE_MASK;
1705 struct page *page = NULL;
1706 unsigned long end_index, nr, ret;
1707 loff_t i_size = i_size_read(inode);
1709 end_index = i_size >> PAGE_CACHE_SHIFT;
1710 if (index > end_index)
1712 if (index == end_index) {
1713 nr = i_size & ~PAGE_CACHE_MASK;
1718 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1720 if (desc->error == -EINVAL)
1728 * We must evaluate after, since reads (unlike writes)
1729 * are called without i_mutex protection against truncate
1731 nr = PAGE_CACHE_SIZE;
1732 i_size = i_size_read(inode);
1733 end_index = i_size >> PAGE_CACHE_SHIFT;
1734 if (index == end_index) {
1735 nr = i_size & ~PAGE_CACHE_MASK;
1738 page_cache_release(page);
1746 * If users can be writing to this page using arbitrary
1747 * virtual addresses, take care about potential aliasing
1748 * before reading the page on the kernel side.
1750 if (mapping_writably_mapped(mapping))
1751 flush_dcache_page(page);
1753 * Mark the page accessed if we read the beginning.
1756 mark_page_accessed(page);
1758 page = ZERO_PAGE(0);
1759 page_cache_get(page);
1763 * Ok, we have the page, and it's up-to-date, so
1764 * now we can copy it to user space...
1766 * The actor routine returns how many bytes were actually used..
1767 * NOTE! This may not be the same as how much of a user buffer
1768 * we filled up (we may be padding etc), so we can only update
1769 * "pos" here (the actor routine has to update the user buffer
1770 * pointers and the remaining count).
1772 ret = actor(desc, page, offset, nr);
1774 index += offset >> PAGE_CACHE_SHIFT;
1775 offset &= ~PAGE_CACHE_MASK;
1777 page_cache_release(page);
1778 if (ret != nr || !desc->count)
1784 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1785 file_accessed(filp);
1788 static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1789 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1791 struct file *filp = iocb->ki_filp;
1795 loff_t *ppos = &iocb->ki_pos;
1797 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1801 for (seg = 0; seg < nr_segs; seg++) {
1802 read_descriptor_t desc;
1805 desc.arg.buf = iov[seg].iov_base;
1806 desc.count = iov[seg].iov_len;
1807 if (desc.count == 0)
1810 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1811 retval += desc.written;
1813 retval = retval ?: desc.error;
1822 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1824 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1826 buf->f_type = TMPFS_MAGIC;
1827 buf->f_bsize = PAGE_CACHE_SIZE;
1828 buf->f_namelen = NAME_MAX;
1829 if (sbinfo->max_blocks) {
1830 buf->f_blocks = sbinfo->max_blocks;
1831 buf->f_bavail = buf->f_bfree =
1832 sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks);
1834 if (sbinfo->max_inodes) {
1835 buf->f_files = sbinfo->max_inodes;
1836 buf->f_ffree = sbinfo->free_inodes;
1838 /* else leave those fields 0 like simple_statfs */
1843 * File creation. Allocate an inode, and we're done..
1846 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1848 struct inode *inode;
1849 int error = -ENOSPC;
1851 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
1853 error = security_inode_init_security(inode, dir,
1854 &dentry->d_name, NULL,
1857 if (error != -EOPNOTSUPP) {
1862 #ifdef CONFIG_TMPFS_POSIX_ACL
1863 error = generic_acl_init(inode, dir);
1871 dir->i_size += BOGO_DIRENT_SIZE;
1872 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1873 d_instantiate(dentry, inode);
1874 dget(dentry); /* Extra count - pin the dentry in core */
1879 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1883 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1889 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1890 struct nameidata *nd)
1892 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1898 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1900 struct inode *inode = old_dentry->d_inode;
1904 * No ordinary (disk based) filesystem counts links as inodes;
1905 * but each new link needs a new dentry, pinning lowmem, and
1906 * tmpfs dentries cannot be pruned until they are unlinked.
1908 ret = shmem_reserve_inode(inode->i_sb);
1912 dir->i_size += BOGO_DIRENT_SIZE;
1913 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1915 ihold(inode); /* New dentry reference */
1916 dget(dentry); /* Extra pinning count for the created dentry */
1917 d_instantiate(dentry, inode);
1922 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1924 struct inode *inode = dentry->d_inode;
1926 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1927 shmem_free_inode(inode->i_sb);
1929 dir->i_size -= BOGO_DIRENT_SIZE;
1930 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1932 dput(dentry); /* Undo the count from "create" - this does all the work */
1936 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1938 if (!simple_empty(dentry))
1941 drop_nlink(dentry->d_inode);
1943 return shmem_unlink(dir, dentry);
1947 * The VFS layer already does all the dentry stuff for rename,
1948 * we just have to decrement the usage count for the target if
1949 * it exists so that the VFS layer correctly free's it when it
1952 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1954 struct inode *inode = old_dentry->d_inode;
1955 int they_are_dirs = S_ISDIR(inode->i_mode);
1957 if (!simple_empty(new_dentry))
1960 if (new_dentry->d_inode) {
1961 (void) shmem_unlink(new_dir, new_dentry);
1963 drop_nlink(old_dir);
1964 } else if (they_are_dirs) {
1965 drop_nlink(old_dir);
1969 old_dir->i_size -= BOGO_DIRENT_SIZE;
1970 new_dir->i_size += BOGO_DIRENT_SIZE;
1971 old_dir->i_ctime = old_dir->i_mtime =
1972 new_dir->i_ctime = new_dir->i_mtime =
1973 inode->i_ctime = CURRENT_TIME;
1977 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1981 struct inode *inode;
1982 struct page *page = NULL;
1984 struct shmem_inode_info *info;
1986 len = strlen(symname) + 1;
1987 if (len > PAGE_CACHE_SIZE)
1988 return -ENAMETOOLONG;
1990 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
1994 error = security_inode_init_security(inode, dir, &dentry->d_name, NULL,
1997 if (error != -EOPNOTSUPP) {
2004 info = SHMEM_I(inode);
2005 inode->i_size = len-1;
2006 if (len <= (char *)inode - (char *)info) {
2008 memcpy(info, symname, len);
2009 inode->i_op = &shmem_symlink_inline_operations;
2011 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2016 inode->i_mapping->a_ops = &shmem_aops;
2017 inode->i_op = &shmem_symlink_inode_operations;
2018 kaddr = kmap_atomic(page, KM_USER0);
2019 memcpy(kaddr, symname, len);
2020 kunmap_atomic(kaddr, KM_USER0);
2021 set_page_dirty(page);
2023 page_cache_release(page);
2025 dir->i_size += BOGO_DIRENT_SIZE;
2026 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2027 d_instantiate(dentry, inode);
2032 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
2034 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
2038 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
2040 struct page *page = NULL;
2041 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2042 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
2048 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2050 if (!IS_ERR(nd_get_link(nd))) {
2051 struct page *page = cookie;
2053 mark_page_accessed(page);
2054 page_cache_release(page);
2058 static const struct inode_operations shmem_symlink_inline_operations = {
2059 .readlink = generic_readlink,
2060 .follow_link = shmem_follow_link_inline,
2063 static const struct inode_operations shmem_symlink_inode_operations = {
2064 .readlink = generic_readlink,
2065 .follow_link = shmem_follow_link,
2066 .put_link = shmem_put_link,
2069 #ifdef CONFIG_TMPFS_POSIX_ACL
2071 * Superblocks without xattr inode operations will get security.* xattr
2072 * support from the VFS "for free". As soon as we have any other xattrs
2073 * like ACLs, we also need to implement the security.* handlers at
2074 * filesystem level, though.
2077 static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
2078 size_t list_len, const char *name,
2079 size_t name_len, int handler_flags)
2081 return security_inode_listsecurity(dentry->d_inode, list, list_len);
2084 static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
2085 void *buffer, size_t size, int handler_flags)
2087 if (strcmp(name, "") == 0)
2089 return xattr_getsecurity(dentry->d_inode, name, buffer, size);
2092 static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
2093 const void *value, size_t size, int flags, int handler_flags)
2095 if (strcmp(name, "") == 0)
2097 return security_inode_setsecurity(dentry->d_inode, name, value,
2101 static const struct xattr_handler shmem_xattr_security_handler = {
2102 .prefix = XATTR_SECURITY_PREFIX,
2103 .list = shmem_xattr_security_list,
2104 .get = shmem_xattr_security_get,
2105 .set = shmem_xattr_security_set,
2108 static const struct xattr_handler *shmem_xattr_handlers[] = {
2109 &generic_acl_access_handler,
2110 &generic_acl_default_handler,
2111 &shmem_xattr_security_handler,
2116 static struct dentry *shmem_get_parent(struct dentry *child)
2118 return ERR_PTR(-ESTALE);
2121 static int shmem_match(struct inode *ino, void *vfh)
2125 inum = (inum << 32) | fh[1];
2126 return ino->i_ino == inum && fh[0] == ino->i_generation;
2129 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2130 struct fid *fid, int fh_len, int fh_type)
2132 struct inode *inode;
2133 struct dentry *dentry = NULL;
2134 u64 inum = fid->raw[2];
2135 inum = (inum << 32) | fid->raw[1];
2140 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2141 shmem_match, fid->raw);
2143 dentry = d_find_alias(inode);
2150 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2153 struct inode *inode = dentry->d_inode;
2160 if (inode_unhashed(inode)) {
2161 /* Unfortunately insert_inode_hash is not idempotent,
2162 * so as we hash inodes here rather than at creation
2163 * time, we need a lock to ensure we only try
2166 static DEFINE_SPINLOCK(lock);
2168 if (inode_unhashed(inode))
2169 __insert_inode_hash(inode,
2170 inode->i_ino + inode->i_generation);
2174 fh[0] = inode->i_generation;
2175 fh[1] = inode->i_ino;
2176 fh[2] = ((__u64)inode->i_ino) >> 32;
2182 static const struct export_operations shmem_export_ops = {
2183 .get_parent = shmem_get_parent,
2184 .encode_fh = shmem_encode_fh,
2185 .fh_to_dentry = shmem_fh_to_dentry,
2188 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2191 char *this_char, *value, *rest;
2193 while (options != NULL) {
2194 this_char = options;
2197 * NUL-terminate this option: unfortunately,
2198 * mount options form a comma-separated list,
2199 * but mpol's nodelist may also contain commas.
2201 options = strchr(options, ',');
2202 if (options == NULL)
2205 if (!isdigit(*options)) {
2212 if ((value = strchr(this_char,'=')) != NULL) {
2216 "tmpfs: No value for mount option '%s'\n",
2221 if (!strcmp(this_char,"size")) {
2222 unsigned long long size;
2223 size = memparse(value,&rest);
2225 size <<= PAGE_SHIFT;
2226 size *= totalram_pages;
2232 sbinfo->max_blocks =
2233 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2234 } else if (!strcmp(this_char,"nr_blocks")) {
2235 sbinfo->max_blocks = memparse(value, &rest);
2238 } else if (!strcmp(this_char,"nr_inodes")) {
2239 sbinfo->max_inodes = memparse(value, &rest);
2242 } else if (!strcmp(this_char,"mode")) {
2245 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2248 } else if (!strcmp(this_char,"uid")) {
2251 sbinfo->uid = simple_strtoul(value, &rest, 0);
2254 } else if (!strcmp(this_char,"gid")) {
2257 sbinfo->gid = simple_strtoul(value, &rest, 0);
2260 } else if (!strcmp(this_char,"mpol")) {
2261 if (mpol_parse_str(value, &sbinfo->mpol, 1))
2264 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2272 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2278 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2280 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2281 struct shmem_sb_info config = *sbinfo;
2282 unsigned long inodes;
2283 int error = -EINVAL;
2285 if (shmem_parse_options(data, &config, true))
2288 spin_lock(&sbinfo->stat_lock);
2289 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2290 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
2292 if (config.max_inodes < inodes)
2295 * Those tests also disallow limited->unlimited while any are in
2296 * use, so i_blocks will always be zero when max_blocks is zero;
2297 * but we must separately disallow unlimited->limited, because
2298 * in that case we have no record of how much is already in use.
2300 if (config.max_blocks && !sbinfo->max_blocks)
2302 if (config.max_inodes && !sbinfo->max_inodes)
2306 sbinfo->max_blocks = config.max_blocks;
2307 sbinfo->max_inodes = config.max_inodes;
2308 sbinfo->free_inodes = config.max_inodes - inodes;
2310 mpol_put(sbinfo->mpol);
2311 sbinfo->mpol = config.mpol; /* transfers initial ref */
2313 spin_unlock(&sbinfo->stat_lock);
2317 static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2319 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2321 if (sbinfo->max_blocks != shmem_default_max_blocks())
2322 seq_printf(seq, ",size=%luk",
2323 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2324 if (sbinfo->max_inodes != shmem_default_max_inodes())
2325 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2326 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2327 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2328 if (sbinfo->uid != 0)
2329 seq_printf(seq, ",uid=%u", sbinfo->uid);
2330 if (sbinfo->gid != 0)
2331 seq_printf(seq, ",gid=%u", sbinfo->gid);
2332 shmem_show_mpol(seq, sbinfo->mpol);
2335 #endif /* CONFIG_TMPFS */
2337 static void shmem_put_super(struct super_block *sb)
2339 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2341 percpu_counter_destroy(&sbinfo->used_blocks);
2343 sb->s_fs_info = NULL;
2346 int shmem_fill_super(struct super_block *sb, void *data, int silent)
2348 struct inode *inode;
2349 struct dentry *root;
2350 struct shmem_sb_info *sbinfo;
2353 /* Round up to L1_CACHE_BYTES to resist false sharing */
2354 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2355 L1_CACHE_BYTES), GFP_KERNEL);
2359 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2360 sbinfo->uid = current_fsuid();
2361 sbinfo->gid = current_fsgid();
2362 sb->s_fs_info = sbinfo;
2366 * Per default we only allow half of the physical ram per
2367 * tmpfs instance, limiting inodes to one per page of lowmem;
2368 * but the internal instance is left unlimited.
2370 if (!(sb->s_flags & MS_NOUSER)) {
2371 sbinfo->max_blocks = shmem_default_max_blocks();
2372 sbinfo->max_inodes = shmem_default_max_inodes();
2373 if (shmem_parse_options(data, sbinfo, false)) {
2378 sb->s_export_op = &shmem_export_ops;
2380 sb->s_flags |= MS_NOUSER;
2383 spin_lock_init(&sbinfo->stat_lock);
2384 if (percpu_counter_init(&sbinfo->used_blocks, 0))
2386 sbinfo->free_inodes = sbinfo->max_inodes;
2388 sb->s_maxbytes = SHMEM_MAX_BYTES;
2389 sb->s_blocksize = PAGE_CACHE_SIZE;
2390 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2391 sb->s_magic = TMPFS_MAGIC;
2392 sb->s_op = &shmem_ops;
2393 sb->s_time_gran = 1;
2394 #ifdef CONFIG_TMPFS_POSIX_ACL
2395 sb->s_xattr = shmem_xattr_handlers;
2396 sb->s_flags |= MS_POSIXACL;
2399 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2402 inode->i_uid = sbinfo->uid;
2403 inode->i_gid = sbinfo->gid;
2404 root = d_alloc_root(inode);
2413 shmem_put_super(sb);
2417 static struct kmem_cache *shmem_inode_cachep;
2419 static struct inode *shmem_alloc_inode(struct super_block *sb)
2421 struct shmem_inode_info *p;
2422 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2425 return &p->vfs_inode;
2428 static void shmem_i_callback(struct rcu_head *head)
2430 struct inode *inode = container_of(head, struct inode, i_rcu);
2431 INIT_LIST_HEAD(&inode->i_dentry);
2432 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2435 static void shmem_destroy_inode(struct inode *inode)
2437 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2438 /* only struct inode is valid if it's an inline symlink */
2439 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2441 call_rcu(&inode->i_rcu, shmem_i_callback);
2444 static void init_once(void *foo)
2446 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2448 inode_init_once(&p->vfs_inode);
2451 static int init_inodecache(void)
2453 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2454 sizeof(struct shmem_inode_info),
2455 0, SLAB_PANIC, init_once);
2459 static void destroy_inodecache(void)
2461 kmem_cache_destroy(shmem_inode_cachep);
2464 static const struct address_space_operations shmem_aops = {
2465 .writepage = shmem_writepage,
2466 .set_page_dirty = __set_page_dirty_no_writeback,
2468 .readpage = shmem_readpage,
2469 .write_begin = shmem_write_begin,
2470 .write_end = shmem_write_end,
2472 .migratepage = migrate_page,
2473 .error_remove_page = generic_error_remove_page,
2476 static const struct file_operations shmem_file_operations = {
2479 .llseek = generic_file_llseek,
2480 .read = do_sync_read,
2481 .write = do_sync_write,
2482 .aio_read = shmem_file_aio_read,
2483 .aio_write = generic_file_aio_write,
2484 .fsync = noop_fsync,
2485 .splice_read = generic_file_splice_read,
2486 .splice_write = generic_file_splice_write,
2490 static const struct inode_operations shmem_inode_operations = {
2491 .setattr = shmem_notify_change,
2492 .truncate_range = shmem_truncate_range,
2493 #ifdef CONFIG_TMPFS_POSIX_ACL
2494 .setxattr = generic_setxattr,
2495 .getxattr = generic_getxattr,
2496 .listxattr = generic_listxattr,
2497 .removexattr = generic_removexattr,
2498 .check_acl = generic_check_acl,
2503 static const struct inode_operations shmem_dir_inode_operations = {
2505 .create = shmem_create,
2506 .lookup = simple_lookup,
2508 .unlink = shmem_unlink,
2509 .symlink = shmem_symlink,
2510 .mkdir = shmem_mkdir,
2511 .rmdir = shmem_rmdir,
2512 .mknod = shmem_mknod,
2513 .rename = shmem_rename,
2515 #ifdef CONFIG_TMPFS_POSIX_ACL
2516 .setattr = shmem_notify_change,
2517 .setxattr = generic_setxattr,
2518 .getxattr = generic_getxattr,
2519 .listxattr = generic_listxattr,
2520 .removexattr = generic_removexattr,
2521 .check_acl = generic_check_acl,
2525 static const struct inode_operations shmem_special_inode_operations = {
2526 #ifdef CONFIG_TMPFS_POSIX_ACL
2527 .setattr = shmem_notify_change,
2528 .setxattr = generic_setxattr,
2529 .getxattr = generic_getxattr,
2530 .listxattr = generic_listxattr,
2531 .removexattr = generic_removexattr,
2532 .check_acl = generic_check_acl,
2536 static const struct super_operations shmem_ops = {
2537 .alloc_inode = shmem_alloc_inode,
2538 .destroy_inode = shmem_destroy_inode,
2540 .statfs = shmem_statfs,
2541 .remount_fs = shmem_remount_fs,
2542 .show_options = shmem_show_options,
2544 .evict_inode = shmem_evict_inode,
2545 .drop_inode = generic_delete_inode,
2546 .put_super = shmem_put_super,
2549 static const struct vm_operations_struct shmem_vm_ops = {
2550 .fault = shmem_fault,
2552 .set_policy = shmem_set_policy,
2553 .get_policy = shmem_get_policy,
2558 static struct dentry *shmem_mount(struct file_system_type *fs_type,
2559 int flags, const char *dev_name, void *data)
2561 return mount_nodev(fs_type, flags, data, shmem_fill_super);
2564 static struct file_system_type tmpfs_fs_type = {
2565 .owner = THIS_MODULE,
2567 .mount = shmem_mount,
2568 .kill_sb = kill_litter_super,
2571 int __init init_tmpfs(void)
2575 error = bdi_init(&shmem_backing_dev_info);
2579 error = init_inodecache();
2583 error = register_filesystem(&tmpfs_fs_type);
2585 printk(KERN_ERR "Could not register tmpfs\n");
2589 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2590 tmpfs_fs_type.name, NULL);
2591 if (IS_ERR(shm_mnt)) {
2592 error = PTR_ERR(shm_mnt);
2593 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2599 unregister_filesystem(&tmpfs_fs_type);
2601 destroy_inodecache();
2603 bdi_destroy(&shmem_backing_dev_info);
2605 shm_mnt = ERR_PTR(error);
2609 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
2611 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2612 * @inode: the inode to be searched
2613 * @pgoff: the offset to be searched
2614 * @pagep: the pointer for the found page to be stored
2615 * @ent: the pointer for the found swap entry to be stored
2617 * If a page is found, refcount of it is incremented. Callers should handle
2620 void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2621 struct page **pagep, swp_entry_t *ent)
2623 swp_entry_t entry = { .val = 0 }, *ptr;
2624 struct page *page = NULL;
2625 struct shmem_inode_info *info = SHMEM_I(inode);
2627 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2630 spin_lock(&info->lock);
2631 ptr = shmem_swp_entry(info, pgoff, NULL);
2633 if (ptr && ptr->val) {
2634 entry.val = ptr->val;
2635 page = find_get_page(&swapper_space, entry.val);
2638 page = find_get_page(inode->i_mapping, pgoff);
2640 shmem_swp_unmap(ptr);
2641 spin_unlock(&info->lock);
2648 #else /* !CONFIG_SHMEM */
2651 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2653 * This is intended for small system where the benefits of the full
2654 * shmem code (swap-backed and resource-limited) are outweighed by
2655 * their complexity. On systems without swap this code should be
2656 * effectively equivalent, but much lighter weight.
2659 #include <linux/ramfs.h>
2661 static struct file_system_type tmpfs_fs_type = {
2663 .mount = ramfs_mount,
2664 .kill_sb = kill_litter_super,
2667 int __init init_tmpfs(void)
2669 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2671 shm_mnt = kern_mount(&tmpfs_fs_type);
2672 BUG_ON(IS_ERR(shm_mnt));
2677 int shmem_unuse(swp_entry_t entry, struct page *page)
2682 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2687 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
2689 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2690 * @inode: the inode to be searched
2691 * @pgoff: the offset to be searched
2692 * @pagep: the pointer for the found page to be stored
2693 * @ent: the pointer for the found swap entry to be stored
2695 * If a page is found, refcount of it is incremented. Callers should handle
2698 void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2699 struct page **pagep, swp_entry_t *ent)
2701 struct page *page = NULL;
2703 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2705 page = find_get_page(inode->i_mapping, pgoff);
2708 *ent = (swp_entry_t){ .val = 0 };
2712 #define shmem_vm_ops generic_file_vm_ops
2713 #define shmem_file_operations ramfs_file_operations
2714 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2715 #define shmem_acct_size(flags, size) 0
2716 #define shmem_unacct_size(flags, size) do {} while (0)
2717 #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
2719 #endif /* CONFIG_SHMEM */
2724 * shmem_file_setup - get an unlinked file living in tmpfs
2725 * @name: name for dentry (to be seen in /proc/<pid>/maps
2726 * @size: size to be set for the file
2727 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2729 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2733 struct inode *inode;
2735 struct dentry *root;
2738 if (IS_ERR(shm_mnt))
2739 return (void *)shm_mnt;
2741 if (size < 0 || size > SHMEM_MAX_BYTES)
2742 return ERR_PTR(-EINVAL);
2744 if (shmem_acct_size(flags, size))
2745 return ERR_PTR(-ENOMEM);
2749 this.len = strlen(name);
2750 this.hash = 0; /* will go */
2751 root = shm_mnt->mnt_root;
2752 path.dentry = d_alloc(root, &this);
2755 path.mnt = mntget(shm_mnt);
2758 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
2762 d_instantiate(path.dentry, inode);
2763 inode->i_size = size;
2764 inode->i_nlink = 0; /* It is unlinked */
2766 error = ramfs_nommu_expand_for_mapping(inode, size);
2772 file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2773 &shmem_file_operations);
2782 shmem_unacct_size(flags, size);
2783 return ERR_PTR(error);
2785 EXPORT_SYMBOL_GPL(shmem_file_setup);
2788 * shmem_zero_setup - setup a shared anonymous mapping
2789 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2791 int shmem_zero_setup(struct vm_area_struct *vma)
2794 loff_t size = vma->vm_end - vma->vm_start;
2796 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2798 return PTR_ERR(file);
2802 vma->vm_file = file;
2803 vma->vm_ops = &shmem_vm_ops;
2804 vma->vm_flags |= VM_CAN_NONLINEAR;