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/swap.h>
33 static struct vfsmount *shm_mnt;
37 * This virtual memory filesystem is heavily based on the ramfs. It
38 * extends ramfs by the ability to use swap and honor resource limits
39 * which makes it a completely usable filesystem.
42 #include <linux/xattr.h>
43 #include <linux/exportfs.h>
44 #include <linux/generic_acl.h>
45 #include <linux/mman.h>
46 #include <linux/string.h>
47 #include <linux/slab.h>
48 #include <linux/backing-dev.h>
49 #include <linux/shmem_fs.h>
50 #include <linux/writeback.h>
51 #include <linux/blkdev.h>
52 #include <linux/security.h>
53 #include <linux/swapops.h>
54 #include <linux/mempolicy.h>
55 #include <linux/namei.h>
56 #include <linux/ctype.h>
57 #include <linux/migrate.h>
58 #include <linux/highmem.h>
59 #include <linux/seq_file.h>
60 #include <linux/magic.h>
62 #include <asm/uaccess.h>
63 #include <asm/div64.h>
64 #include <asm/pgtable.h>
67 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
68 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
70 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
71 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
72 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
73 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
75 * We use / and * instead of shifts in the definitions below, so that the swap
76 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
78 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
79 #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
81 #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
82 #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
84 #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
85 #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
87 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
88 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
90 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
91 #define SHMEM_PAGEIN VM_READ
92 #define SHMEM_TRUNCATE VM_WRITE
94 /* Definition to limit shmem_truncate's steps between cond_rescheds */
95 #define LATENCY_LIMIT 64
97 /* Pretend that each entry is of this size in directory's i_size */
98 #define BOGO_DIRENT_SIZE 20
100 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
102 SGP_READ, /* don't exceed i_size, don't allocate page */
103 SGP_CACHE, /* don't exceed i_size, may allocate page */
104 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
105 SGP_WRITE, /* may exceed i_size, may allocate page */
109 static unsigned long shmem_default_max_blocks(void)
111 return totalram_pages / 2;
114 static unsigned long shmem_default_max_inodes(void)
116 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
120 static int shmem_getpage(struct inode *inode, unsigned long idx,
121 struct page **pagep, enum sgp_type sgp, int *type);
123 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
126 * The above definition of ENTRIES_PER_PAGE, and the use of
127 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
128 * might be reconsidered if it ever diverges from PAGE_SIZE.
130 * Mobility flags are masked out as swap vectors cannot move
132 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
133 PAGE_CACHE_SHIFT-PAGE_SHIFT);
136 static inline void shmem_dir_free(struct page *page)
138 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
141 static struct page **shmem_dir_map(struct page *page)
143 return (struct page **)kmap_atomic(page, KM_USER0);
146 static inline void shmem_dir_unmap(struct page **dir)
148 kunmap_atomic(dir, KM_USER0);
151 static swp_entry_t *shmem_swp_map(struct page *page)
153 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
156 static inline void shmem_swp_balance_unmap(void)
159 * When passing a pointer to an i_direct entry, to code which
160 * also handles indirect entries and so will shmem_swp_unmap,
161 * we must arrange for the preempt count to remain in balance.
162 * What kmap_atomic of a lowmem page does depends on config
163 * and architecture, so pretend to kmap_atomic some lowmem page.
165 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
168 static inline void shmem_swp_unmap(swp_entry_t *entry)
170 kunmap_atomic(entry, KM_USER1);
173 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
175 return sb->s_fs_info;
179 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
180 * for shared memory and for shared anonymous (/dev/zero) mappings
181 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
182 * consistent with the pre-accounting of private mappings ...
184 static inline int shmem_acct_size(unsigned long flags, loff_t size)
186 return (flags & VM_NORESERVE) ?
187 0 : security_vm_enough_memory_kern(VM_ACCT(size));
190 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
192 if (!(flags & VM_NORESERVE))
193 vm_unacct_memory(VM_ACCT(size));
197 * ... whereas tmpfs objects are accounted incrementally as
198 * pages are allocated, in order to allow huge sparse files.
199 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
200 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
202 static inline int shmem_acct_block(unsigned long flags)
204 return (flags & VM_NORESERVE) ?
205 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
208 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
210 if (flags & VM_NORESERVE)
211 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
214 static const struct super_operations shmem_ops;
215 static const struct address_space_operations shmem_aops;
216 static const struct file_operations shmem_file_operations;
217 static const struct inode_operations shmem_inode_operations;
218 static const struct inode_operations shmem_dir_inode_operations;
219 static const struct inode_operations shmem_special_inode_operations;
220 static const struct vm_operations_struct shmem_vm_ops;
222 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
223 .ra_pages = 0, /* No readahead */
224 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
225 .unplug_io_fn = default_unplug_io_fn,
228 static LIST_HEAD(shmem_swaplist);
229 static DEFINE_MUTEX(shmem_swaplist_mutex);
231 static void shmem_free_blocks(struct inode *inode, long pages)
233 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
234 if (sbinfo->max_blocks) {
235 spin_lock(&sbinfo->stat_lock);
236 sbinfo->free_blocks += pages;
237 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
238 spin_unlock(&sbinfo->stat_lock);
242 static int shmem_reserve_inode(struct super_block *sb)
244 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
245 if (sbinfo->max_inodes) {
246 spin_lock(&sbinfo->stat_lock);
247 if (!sbinfo->free_inodes) {
248 spin_unlock(&sbinfo->stat_lock);
251 sbinfo->free_inodes--;
252 spin_unlock(&sbinfo->stat_lock);
257 static void shmem_free_inode(struct super_block *sb)
259 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
260 if (sbinfo->max_inodes) {
261 spin_lock(&sbinfo->stat_lock);
262 sbinfo->free_inodes++;
263 spin_unlock(&sbinfo->stat_lock);
268 * shmem_recalc_inode - recalculate the size of an inode
269 * @inode: inode to recalc
271 * We have to calculate the free blocks since the mm can drop
272 * undirtied hole pages behind our back.
274 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
275 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
277 * It has to be called with the spinlock held.
279 static void shmem_recalc_inode(struct inode *inode)
281 struct shmem_inode_info *info = SHMEM_I(inode);
284 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
286 info->alloced -= freed;
287 shmem_unacct_blocks(info->flags, freed);
288 shmem_free_blocks(inode, freed);
293 * shmem_swp_entry - find the swap vector position in the info structure
294 * @info: info structure for the inode
295 * @index: index of the page to find
296 * @page: optional page to add to the structure. Has to be preset to
299 * If there is no space allocated yet it will return NULL when
300 * page is NULL, else it will use the page for the needed block,
301 * setting it to NULL on return to indicate that it has been used.
303 * The swap vector is organized the following way:
305 * There are SHMEM_NR_DIRECT entries directly stored in the
306 * shmem_inode_info structure. So small files do not need an addional
309 * For pages with index > SHMEM_NR_DIRECT there is the pointer
310 * i_indirect which points to a page which holds in the first half
311 * doubly indirect blocks, in the second half triple indirect blocks:
313 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
314 * following layout (for SHMEM_NR_DIRECT == 16):
316 * i_indirect -> dir --> 16-19
329 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
331 unsigned long offset;
335 if (index < SHMEM_NR_DIRECT) {
336 shmem_swp_balance_unmap();
337 return info->i_direct+index;
339 if (!info->i_indirect) {
341 info->i_indirect = *page;
344 return NULL; /* need another page */
347 index -= SHMEM_NR_DIRECT;
348 offset = index % ENTRIES_PER_PAGE;
349 index /= ENTRIES_PER_PAGE;
350 dir = shmem_dir_map(info->i_indirect);
352 if (index >= ENTRIES_PER_PAGE/2) {
353 index -= ENTRIES_PER_PAGE/2;
354 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
355 index %= ENTRIES_PER_PAGE;
362 shmem_dir_unmap(dir);
363 return NULL; /* need another page */
365 shmem_dir_unmap(dir);
366 dir = shmem_dir_map(subdir);
372 if (!page || !(subdir = *page)) {
373 shmem_dir_unmap(dir);
374 return NULL; /* need a page */
379 shmem_dir_unmap(dir);
380 return shmem_swp_map(subdir) + offset;
383 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
385 long incdec = value? 1: -1;
388 info->swapped += incdec;
389 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
390 struct page *page = kmap_atomic_to_page(entry);
391 set_page_private(page, page_private(page) + incdec);
396 * shmem_swp_alloc - get the position of the swap entry for the page.
397 * @info: info structure for the inode
398 * @index: index of the page to find
399 * @sgp: check and recheck i_size? skip allocation?
401 * If the entry does not exist, allocate it.
403 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
405 struct inode *inode = &info->vfs_inode;
406 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
407 struct page *page = NULL;
410 if (sgp != SGP_WRITE &&
411 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
412 return ERR_PTR(-EINVAL);
414 while (!(entry = shmem_swp_entry(info, index, &page))) {
416 return shmem_swp_map(ZERO_PAGE(0));
418 * Test free_blocks against 1 not 0, since we have 1 data
419 * page (and perhaps indirect index pages) yet to allocate:
420 * a waste to allocate index if we cannot allocate data.
422 if (sbinfo->max_blocks) {
423 spin_lock(&sbinfo->stat_lock);
424 if (sbinfo->free_blocks <= 1) {
425 spin_unlock(&sbinfo->stat_lock);
426 return ERR_PTR(-ENOSPC);
428 sbinfo->free_blocks--;
429 inode->i_blocks += BLOCKS_PER_PAGE;
430 spin_unlock(&sbinfo->stat_lock);
433 spin_unlock(&info->lock);
434 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
436 set_page_private(page, 0);
437 spin_lock(&info->lock);
440 shmem_free_blocks(inode, 1);
441 return ERR_PTR(-ENOMEM);
443 if (sgp != SGP_WRITE &&
444 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
445 entry = ERR_PTR(-EINVAL);
448 if (info->next_index <= index)
449 info->next_index = index + 1;
452 /* another task gave its page, or truncated the file */
453 shmem_free_blocks(inode, 1);
454 shmem_dir_free(page);
456 if (info->next_index <= index && !IS_ERR(entry))
457 info->next_index = index + 1;
462 * shmem_free_swp - free some swap entries in a directory
463 * @dir: pointer to the directory
464 * @edir: pointer after last entry of the directory
465 * @punch_lock: pointer to spinlock when needed for the holepunch case
467 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
468 spinlock_t *punch_lock)
470 spinlock_t *punch_unlock = NULL;
474 for (ptr = dir; ptr < edir; ptr++) {
476 if (unlikely(punch_lock)) {
477 punch_unlock = punch_lock;
479 spin_lock(punch_unlock);
483 free_swap_and_cache(*ptr);
484 *ptr = (swp_entry_t){0};
489 spin_unlock(punch_unlock);
493 static int shmem_map_and_free_swp(struct page *subdir, int offset,
494 int limit, struct page ***dir, spinlock_t *punch_lock)
499 ptr = shmem_swp_map(subdir);
500 for (; offset < limit; offset += LATENCY_LIMIT) {
501 int size = limit - offset;
502 if (size > LATENCY_LIMIT)
503 size = LATENCY_LIMIT;
504 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
506 if (need_resched()) {
507 shmem_swp_unmap(ptr);
509 shmem_dir_unmap(*dir);
513 ptr = shmem_swp_map(subdir);
516 shmem_swp_unmap(ptr);
520 static void shmem_free_pages(struct list_head *next)
526 page = container_of(next, struct page, lru);
528 shmem_dir_free(page);
530 if (freed >= LATENCY_LIMIT) {
537 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
539 struct shmem_inode_info *info = SHMEM_I(inode);
544 unsigned long diroff;
550 LIST_HEAD(pages_to_free);
551 long nr_pages_to_free = 0;
552 long nr_swaps_freed = 0;
556 spinlock_t *needs_lock;
557 spinlock_t *punch_lock;
558 unsigned long upper_limit;
560 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
561 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
562 if (idx >= info->next_index)
565 spin_lock(&info->lock);
566 info->flags |= SHMEM_TRUNCATE;
567 if (likely(end == (loff_t) -1)) {
568 limit = info->next_index;
569 upper_limit = SHMEM_MAX_INDEX;
570 info->next_index = idx;
574 if (end + 1 >= inode->i_size) { /* we may free a little more */
575 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
577 upper_limit = SHMEM_MAX_INDEX;
579 limit = (end + 1) >> PAGE_CACHE_SHIFT;
582 needs_lock = &info->lock;
586 topdir = info->i_indirect;
587 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
588 info->i_indirect = NULL;
590 list_add(&topdir->lru, &pages_to_free);
592 spin_unlock(&info->lock);
594 if (info->swapped && idx < SHMEM_NR_DIRECT) {
595 ptr = info->i_direct;
597 if (size > SHMEM_NR_DIRECT)
598 size = SHMEM_NR_DIRECT;
599 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
603 * If there are no indirect blocks or we are punching a hole
604 * below indirect blocks, nothing to be done.
606 if (!topdir || limit <= SHMEM_NR_DIRECT)
610 * The truncation case has already dropped info->lock, and we're safe
611 * because i_size and next_index have already been lowered, preventing
612 * access beyond. But in the punch_hole case, we still need to take
613 * the lock when updating the swap directory, because there might be
614 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
615 * shmem_writepage. However, whenever we find we can remove a whole
616 * directory page (not at the misaligned start or end of the range),
617 * we first NULLify its pointer in the level above, and then have no
618 * need to take the lock when updating its contents: needs_lock and
619 * punch_lock (either pointing to info->lock or NULL) manage this.
622 upper_limit -= SHMEM_NR_DIRECT;
623 limit -= SHMEM_NR_DIRECT;
624 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
625 offset = idx % ENTRIES_PER_PAGE;
628 dir = shmem_dir_map(topdir);
629 stage = ENTRIES_PER_PAGEPAGE/2;
630 if (idx < ENTRIES_PER_PAGEPAGE/2) {
632 diroff = idx/ENTRIES_PER_PAGE;
634 dir += ENTRIES_PER_PAGE/2;
635 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
637 stage += ENTRIES_PER_PAGEPAGE;
640 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
641 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
642 if (!diroff && !offset && upper_limit >= stage) {
644 spin_lock(needs_lock);
646 spin_unlock(needs_lock);
651 list_add(&middir->lru, &pages_to_free);
653 shmem_dir_unmap(dir);
654 dir = shmem_dir_map(middir);
662 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
663 if (unlikely(idx == stage)) {
664 shmem_dir_unmap(dir);
665 dir = shmem_dir_map(topdir) +
666 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
669 idx += ENTRIES_PER_PAGEPAGE;
673 stage = idx + ENTRIES_PER_PAGEPAGE;
676 needs_lock = &info->lock;
677 if (upper_limit >= stage) {
679 spin_lock(needs_lock);
681 spin_unlock(needs_lock);
686 list_add(&middir->lru, &pages_to_free);
688 shmem_dir_unmap(dir);
690 dir = shmem_dir_map(middir);
693 punch_lock = needs_lock;
694 subdir = dir[diroff];
695 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
697 spin_lock(needs_lock);
699 spin_unlock(needs_lock);
704 list_add(&subdir->lru, &pages_to_free);
706 if (subdir && page_private(subdir) /* has swap entries */) {
708 if (size > ENTRIES_PER_PAGE)
709 size = ENTRIES_PER_PAGE;
710 freed = shmem_map_and_free_swp(subdir,
711 offset, size, &dir, punch_lock);
713 dir = shmem_dir_map(middir);
714 nr_swaps_freed += freed;
715 if (offset || punch_lock) {
716 spin_lock(&info->lock);
717 set_page_private(subdir,
718 page_private(subdir) - freed);
719 spin_unlock(&info->lock);
721 BUG_ON(page_private(subdir) != freed);
726 shmem_dir_unmap(dir);
728 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
730 * Call truncate_inode_pages again: racing shmem_unuse_inode
731 * may have swizzled a page in from swap since vmtruncate or
732 * generic_delete_inode did it, before we lowered next_index.
733 * Also, though shmem_getpage checks i_size before adding to
734 * cache, no recheck after: so fix the narrow window there too.
736 * Recalling truncate_inode_pages_range and unmap_mapping_range
737 * every time for punch_hole (which never got a chance to clear
738 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
739 * yet hardly ever necessary: try to optimize them out later.
741 truncate_inode_pages_range(inode->i_mapping, start, end);
743 unmap_mapping_range(inode->i_mapping, start,
747 spin_lock(&info->lock);
748 info->flags &= ~SHMEM_TRUNCATE;
749 info->swapped -= nr_swaps_freed;
750 if (nr_pages_to_free)
751 shmem_free_blocks(inode, nr_pages_to_free);
752 shmem_recalc_inode(inode);
753 spin_unlock(&info->lock);
756 * Empty swap vector directory pages to be freed?
758 if (!list_empty(&pages_to_free)) {
759 pages_to_free.prev->next = NULL;
760 shmem_free_pages(pages_to_free.next);
764 static void shmem_truncate(struct inode *inode)
766 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
769 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
771 struct inode *inode = dentry->d_inode;
772 struct page *page = NULL;
775 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
776 if (attr->ia_size < inode->i_size) {
778 * If truncating down to a partial page, then
779 * if that page is already allocated, hold it
780 * in memory until the truncation is over, so
781 * truncate_partial_page cannnot miss it were
782 * it assigned to swap.
784 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
785 (void) shmem_getpage(inode,
786 attr->ia_size>>PAGE_CACHE_SHIFT,
787 &page, SGP_READ, NULL);
792 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
793 * detect if any pages might have been added to cache
794 * after truncate_inode_pages. But we needn't bother
795 * if it's being fully truncated to zero-length: the
796 * nrpages check is efficient enough in that case.
799 struct shmem_inode_info *info = SHMEM_I(inode);
800 spin_lock(&info->lock);
801 info->flags &= ~SHMEM_PAGEIN;
802 spin_unlock(&info->lock);
807 error = inode_change_ok(inode, attr);
809 error = inode_setattr(inode, attr);
810 #ifdef CONFIG_TMPFS_POSIX_ACL
811 if (!error && (attr->ia_valid & ATTR_MODE))
812 error = generic_acl_chmod(inode, &shmem_acl_ops);
815 page_cache_release(page);
819 static void shmem_delete_inode(struct inode *inode)
821 struct shmem_inode_info *info = SHMEM_I(inode);
823 if (inode->i_op->truncate == shmem_truncate) {
824 truncate_inode_pages(inode->i_mapping, 0);
825 shmem_unacct_size(info->flags, inode->i_size);
827 shmem_truncate(inode);
828 if (!list_empty(&info->swaplist)) {
829 mutex_lock(&shmem_swaplist_mutex);
830 list_del_init(&info->swaplist);
831 mutex_unlock(&shmem_swaplist_mutex);
834 BUG_ON(inode->i_blocks);
835 shmem_free_inode(inode->i_sb);
839 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
843 for (ptr = dir; ptr < edir; ptr++) {
844 if (ptr->val == entry.val)
850 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
864 ptr = info->i_direct;
865 spin_lock(&info->lock);
866 if (!info->swapped) {
867 list_del_init(&info->swaplist);
870 limit = info->next_index;
872 if (size > SHMEM_NR_DIRECT)
873 size = SHMEM_NR_DIRECT;
874 offset = shmem_find_swp(entry, ptr, ptr+size);
877 if (!info->i_indirect)
880 dir = shmem_dir_map(info->i_indirect);
881 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
883 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
884 if (unlikely(idx == stage)) {
885 shmem_dir_unmap(dir-1);
886 if (cond_resched_lock(&info->lock)) {
887 /* check it has not been truncated */
888 if (limit > info->next_index) {
889 limit = info->next_index;
894 dir = shmem_dir_map(info->i_indirect) +
895 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
898 idx += ENTRIES_PER_PAGEPAGE;
902 stage = idx + ENTRIES_PER_PAGEPAGE;
904 shmem_dir_unmap(dir);
905 dir = shmem_dir_map(subdir);
908 if (subdir && page_private(subdir)) {
909 ptr = shmem_swp_map(subdir);
911 if (size > ENTRIES_PER_PAGE)
912 size = ENTRIES_PER_PAGE;
913 offset = shmem_find_swp(entry, ptr, ptr+size);
914 shmem_swp_unmap(ptr);
916 shmem_dir_unmap(dir);
922 shmem_dir_unmap(dir-1);
924 spin_unlock(&info->lock);
928 inode = igrab(&info->vfs_inode);
929 spin_unlock(&info->lock);
932 * Move _head_ to start search for next from here.
933 * But be careful: shmem_delete_inode checks list_empty without taking
934 * mutex, and there's an instant in list_move_tail when info->swaplist
935 * would appear empty, if it were the only one on shmem_swaplist. We
936 * could avoid doing it if inode NULL; or use this minor optimization.
938 if (shmem_swaplist.next != &info->swaplist)
939 list_move_tail(&shmem_swaplist, &info->swaplist);
940 mutex_unlock(&shmem_swaplist_mutex);
946 * Charge page using GFP_KERNEL while we can wait.
947 * Charged back to the user(not to caller) when swap account is used.
948 * add_to_page_cache() will be called with GFP_NOWAIT.
950 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
953 error = radix_tree_preload(GFP_KERNEL);
955 mem_cgroup_uncharge_cache_page(page);
960 spin_lock(&info->lock);
961 ptr = shmem_swp_entry(info, idx, NULL);
962 if (ptr && ptr->val == entry.val) {
963 error = add_to_page_cache_locked(page, inode->i_mapping,
965 /* does mem_cgroup_uncharge_cache_page on error */
966 } else /* we must compensate for our precharge above */
967 mem_cgroup_uncharge_cache_page(page);
969 if (error == -EEXIST) {
970 struct page *filepage = find_get_page(inode->i_mapping, idx);
974 * There might be a more uptodate page coming down
975 * from a stacked writepage: forget our swappage if so.
977 if (PageUptodate(filepage))
979 page_cache_release(filepage);
983 delete_from_swap_cache(page);
984 set_page_dirty(page);
985 info->flags |= SHMEM_PAGEIN;
986 shmem_swp_set(info, ptr, 0);
988 error = 1; /* not an error, but entry was found */
991 shmem_swp_unmap(ptr);
992 spin_unlock(&info->lock);
993 radix_tree_preload_end();
996 page_cache_release(page);
997 iput(inode); /* allows for NULL */
1002 * shmem_unuse() search for an eventually swapped out shmem page.
1004 int shmem_unuse(swp_entry_t entry, struct page *page)
1006 struct list_head *p, *next;
1007 struct shmem_inode_info *info;
1010 mutex_lock(&shmem_swaplist_mutex);
1011 list_for_each_safe(p, next, &shmem_swaplist) {
1012 info = list_entry(p, struct shmem_inode_info, swaplist);
1013 found = shmem_unuse_inode(info, entry, page);
1018 mutex_unlock(&shmem_swaplist_mutex);
1020 * Can some race bring us here? We've been holding page lock,
1021 * so I think not; but would rather try again later than BUG()
1024 page_cache_release(page);
1026 return (found < 0) ? found : 0;
1030 * Move the page from the page cache to the swap cache.
1032 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1034 struct shmem_inode_info *info;
1035 swp_entry_t *entry, swap;
1036 struct address_space *mapping;
1037 unsigned long index;
1038 struct inode *inode;
1040 BUG_ON(!PageLocked(page));
1041 mapping = page->mapping;
1042 index = page->index;
1043 inode = mapping->host;
1044 info = SHMEM_I(inode);
1045 if (info->flags & VM_LOCKED)
1047 if (!total_swap_pages)
1051 * shmem_backing_dev_info's capabilities prevent regular writeback or
1052 * sync from ever calling shmem_writepage; but a stacking filesystem
1053 * may use the ->writepage of its underlying filesystem, in which case
1054 * tmpfs should write out to swap only in response to memory pressure,
1055 * and not for the writeback threads or sync. However, in those cases,
1056 * we do still want to check if there's a redundant swappage to be
1059 if (wbc->for_reclaim)
1060 swap = get_swap_page();
1064 spin_lock(&info->lock);
1065 if (index >= info->next_index) {
1066 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1069 entry = shmem_swp_entry(info, index, NULL);
1072 * The more uptodate page coming down from a stacked
1073 * writepage should replace our old swappage.
1075 free_swap_and_cache(*entry);
1076 shmem_swp_set(info, entry, 0);
1078 shmem_recalc_inode(inode);
1080 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1081 remove_from_page_cache(page);
1082 shmem_swp_set(info, entry, swap.val);
1083 shmem_swp_unmap(entry);
1084 if (list_empty(&info->swaplist))
1085 inode = igrab(inode);
1088 spin_unlock(&info->lock);
1089 swap_shmem_alloc(swap);
1090 BUG_ON(page_mapped(page));
1091 page_cache_release(page); /* pagecache ref */
1092 swap_writepage(page, wbc);
1094 mutex_lock(&shmem_swaplist_mutex);
1095 /* move instead of add in case we're racing */
1096 list_move_tail(&info->swaplist, &shmem_swaplist);
1097 mutex_unlock(&shmem_swaplist_mutex);
1103 shmem_swp_unmap(entry);
1105 spin_unlock(&info->lock);
1107 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1108 * clear SWAP_HAS_CACHE flag.
1110 swapcache_free(swap, NULL);
1112 set_page_dirty(page);
1113 if (wbc->for_reclaim)
1114 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1121 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1125 if (!mpol || mpol->mode == MPOL_DEFAULT)
1126 return; /* show nothing */
1128 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
1130 seq_printf(seq, ",mpol=%s", buffer);
1133 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1135 struct mempolicy *mpol = NULL;
1137 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1138 mpol = sbinfo->mpol;
1140 spin_unlock(&sbinfo->stat_lock);
1144 #endif /* CONFIG_TMPFS */
1146 static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1147 struct shmem_inode_info *info, unsigned long idx)
1149 struct mempolicy mpol, *spol;
1150 struct vm_area_struct pvma;
1153 spol = mpol_cond_copy(&mpol,
1154 mpol_shared_policy_lookup(&info->policy, idx));
1156 /* Create a pseudo vma that just contains the policy */
1158 pvma.vm_pgoff = idx;
1160 pvma.vm_policy = spol;
1161 page = swapin_readahead(entry, gfp, &pvma, 0);
1165 static struct page *shmem_alloc_page(gfp_t gfp,
1166 struct shmem_inode_info *info, unsigned long idx)
1168 struct vm_area_struct pvma;
1170 /* Create a pseudo vma that just contains the policy */
1172 pvma.vm_pgoff = idx;
1174 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1177 * alloc_page_vma() will drop the shared policy reference
1179 return alloc_page_vma(gfp, &pvma, 0);
1181 #else /* !CONFIG_NUMA */
1183 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
1186 #endif /* CONFIG_TMPFS */
1188 static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1189 struct shmem_inode_info *info, unsigned long idx)
1191 return swapin_readahead(entry, gfp, NULL, 0);
1194 static inline struct page *shmem_alloc_page(gfp_t gfp,
1195 struct shmem_inode_info *info, unsigned long idx)
1197 return alloc_page(gfp);
1199 #endif /* CONFIG_NUMA */
1201 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1202 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1209 * shmem_getpage - either get the page from swap or allocate a new one
1211 * If we allocate a new one we do not mark it dirty. That's up to the
1212 * vm. If we swap it in we mark it dirty since we also free the swap
1213 * entry since a page cannot live in both the swap and page cache
1215 static int shmem_getpage(struct inode *inode, unsigned long idx,
1216 struct page **pagep, enum sgp_type sgp, int *type)
1218 struct address_space *mapping = inode->i_mapping;
1219 struct shmem_inode_info *info = SHMEM_I(inode);
1220 struct shmem_sb_info *sbinfo;
1221 struct page *filepage = *pagep;
1222 struct page *swappage;
1228 if (idx >= SHMEM_MAX_INDEX)
1235 * Normally, filepage is NULL on entry, and either found
1236 * uptodate immediately, or allocated and zeroed, or read
1237 * in under swappage, which is then assigned to filepage.
1238 * But shmem_readpage (required for splice) passes in a locked
1239 * filepage, which may be found not uptodate by other callers
1240 * too, and may need to be copied from the swappage read in.
1244 filepage = find_lock_page(mapping, idx);
1245 if (filepage && PageUptodate(filepage))
1248 gfp = mapping_gfp_mask(mapping);
1251 * Try to preload while we can wait, to not make a habit of
1252 * draining atomic reserves; but don't latch on to this cpu.
1254 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1257 radix_tree_preload_end();
1260 spin_lock(&info->lock);
1261 shmem_recalc_inode(inode);
1262 entry = shmem_swp_alloc(info, idx, sgp);
1263 if (IS_ERR(entry)) {
1264 spin_unlock(&info->lock);
1265 error = PTR_ERR(entry);
1271 /* Look it up and read it in.. */
1272 swappage = lookup_swap_cache(swap);
1274 shmem_swp_unmap(entry);
1275 /* here we actually do the io */
1276 if (type && !(*type & VM_FAULT_MAJOR)) {
1277 __count_vm_event(PGMAJFAULT);
1278 *type |= VM_FAULT_MAJOR;
1280 spin_unlock(&info->lock);
1281 swappage = shmem_swapin(swap, gfp, info, idx);
1283 spin_lock(&info->lock);
1284 entry = shmem_swp_alloc(info, idx, sgp);
1286 error = PTR_ERR(entry);
1288 if (entry->val == swap.val)
1290 shmem_swp_unmap(entry);
1292 spin_unlock(&info->lock);
1297 wait_on_page_locked(swappage);
1298 page_cache_release(swappage);
1302 /* We have to do this with page locked to prevent races */
1303 if (!trylock_page(swappage)) {
1304 shmem_swp_unmap(entry);
1305 spin_unlock(&info->lock);
1306 wait_on_page_locked(swappage);
1307 page_cache_release(swappage);
1310 if (PageWriteback(swappage)) {
1311 shmem_swp_unmap(entry);
1312 spin_unlock(&info->lock);
1313 wait_on_page_writeback(swappage);
1314 unlock_page(swappage);
1315 page_cache_release(swappage);
1318 if (!PageUptodate(swappage)) {
1319 shmem_swp_unmap(entry);
1320 spin_unlock(&info->lock);
1321 unlock_page(swappage);
1322 page_cache_release(swappage);
1328 shmem_swp_set(info, entry, 0);
1329 shmem_swp_unmap(entry);
1330 delete_from_swap_cache(swappage);
1331 spin_unlock(&info->lock);
1332 copy_highpage(filepage, swappage);
1333 unlock_page(swappage);
1334 page_cache_release(swappage);
1335 flush_dcache_page(filepage);
1336 SetPageUptodate(filepage);
1337 set_page_dirty(filepage);
1339 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1340 idx, GFP_NOWAIT))) {
1341 info->flags |= SHMEM_PAGEIN;
1342 shmem_swp_set(info, entry, 0);
1343 shmem_swp_unmap(entry);
1344 delete_from_swap_cache(swappage);
1345 spin_unlock(&info->lock);
1346 filepage = swappage;
1347 set_page_dirty(filepage);
1350 shmem_swp_unmap(entry);
1351 spin_unlock(&info->lock);
1352 if (error == -ENOMEM) {
1354 * reclaim from proper memory cgroup and
1355 * call memcg's OOM if needed.
1357 error = mem_cgroup_shmem_charge_fallback(
1362 unlock_page(swappage);
1363 page_cache_release(swappage);
1367 unlock_page(swappage);
1368 page_cache_release(swappage);
1371 } else if (sgp == SGP_READ && !filepage) {
1372 shmem_swp_unmap(entry);
1373 filepage = find_get_page(mapping, idx);
1375 (!PageUptodate(filepage) || !trylock_page(filepage))) {
1376 spin_unlock(&info->lock);
1377 wait_on_page_locked(filepage);
1378 page_cache_release(filepage);
1382 spin_unlock(&info->lock);
1384 shmem_swp_unmap(entry);
1385 sbinfo = SHMEM_SB(inode->i_sb);
1386 if (sbinfo->max_blocks) {
1387 spin_lock(&sbinfo->stat_lock);
1388 if (sbinfo->free_blocks == 0 ||
1389 shmem_acct_block(info->flags)) {
1390 spin_unlock(&sbinfo->stat_lock);
1391 spin_unlock(&info->lock);
1395 sbinfo->free_blocks--;
1396 inode->i_blocks += BLOCKS_PER_PAGE;
1397 spin_unlock(&sbinfo->stat_lock);
1398 } else if (shmem_acct_block(info->flags)) {
1399 spin_unlock(&info->lock);
1407 spin_unlock(&info->lock);
1408 filepage = shmem_alloc_page(gfp, info, idx);
1410 shmem_unacct_blocks(info->flags, 1);
1411 shmem_free_blocks(inode, 1);
1415 SetPageSwapBacked(filepage);
1417 /* Precharge page while we can wait, compensate after */
1418 error = mem_cgroup_cache_charge(filepage, current->mm,
1421 page_cache_release(filepage);
1422 shmem_unacct_blocks(info->flags, 1);
1423 shmem_free_blocks(inode, 1);
1428 spin_lock(&info->lock);
1429 entry = shmem_swp_alloc(info, idx, sgp);
1431 error = PTR_ERR(entry);
1434 shmem_swp_unmap(entry);
1436 ret = error || swap.val;
1438 mem_cgroup_uncharge_cache_page(filepage);
1440 ret = add_to_page_cache_lru(filepage, mapping,
1443 * At add_to_page_cache_lru() failure, uncharge will
1444 * be done automatically.
1447 spin_unlock(&info->lock);
1448 page_cache_release(filepage);
1449 shmem_unacct_blocks(info->flags, 1);
1450 shmem_free_blocks(inode, 1);
1456 info->flags |= SHMEM_PAGEIN;
1460 spin_unlock(&info->lock);
1461 clear_highpage(filepage);
1462 flush_dcache_page(filepage);
1463 SetPageUptodate(filepage);
1464 if (sgp == SGP_DIRTY)
1465 set_page_dirty(filepage);
1472 if (*pagep != filepage) {
1473 unlock_page(filepage);
1474 page_cache_release(filepage);
1479 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1481 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1485 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1486 return VM_FAULT_SIGBUS;
1488 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1490 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1492 return ret | VM_FAULT_LOCKED;
1496 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1498 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1499 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1502 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1505 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1508 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1509 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1513 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1515 struct inode *inode = file->f_path.dentry->d_inode;
1516 struct shmem_inode_info *info = SHMEM_I(inode);
1517 int retval = -ENOMEM;
1519 spin_lock(&info->lock);
1520 if (lock && !(info->flags & VM_LOCKED)) {
1521 if (!user_shm_lock(inode->i_size, user))
1523 info->flags |= VM_LOCKED;
1524 mapping_set_unevictable(file->f_mapping);
1526 if (!lock && (info->flags & VM_LOCKED) && user) {
1527 user_shm_unlock(inode->i_size, user);
1528 info->flags &= ~VM_LOCKED;
1529 mapping_clear_unevictable(file->f_mapping);
1530 scan_mapping_unevictable_pages(file->f_mapping);
1535 spin_unlock(&info->lock);
1539 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1541 file_accessed(file);
1542 vma->vm_ops = &shmem_vm_ops;
1543 vma->vm_flags |= VM_CAN_NONLINEAR;
1547 static struct inode *shmem_get_inode(struct super_block *sb, int mode,
1548 dev_t dev, unsigned long flags)
1550 struct inode *inode;
1551 struct shmem_inode_info *info;
1552 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1554 if (shmem_reserve_inode(sb))
1557 inode = new_inode(sb);
1559 inode->i_mode = mode;
1560 inode->i_uid = current_fsuid();
1561 inode->i_gid = current_fsgid();
1562 inode->i_blocks = 0;
1563 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1564 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1565 inode->i_generation = get_seconds();
1566 info = SHMEM_I(inode);
1567 memset(info, 0, (char *)inode - (char *)info);
1568 spin_lock_init(&info->lock);
1569 info->flags = flags & VM_NORESERVE;
1570 INIT_LIST_HEAD(&info->swaplist);
1571 cache_no_acl(inode);
1573 switch (mode & S_IFMT) {
1575 inode->i_op = &shmem_special_inode_operations;
1576 init_special_inode(inode, mode, dev);
1579 inode->i_mapping->a_ops = &shmem_aops;
1580 inode->i_op = &shmem_inode_operations;
1581 inode->i_fop = &shmem_file_operations;
1582 mpol_shared_policy_init(&info->policy,
1583 shmem_get_sbmpol(sbinfo));
1587 /* Some things misbehave if size == 0 on a directory */
1588 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1589 inode->i_op = &shmem_dir_inode_operations;
1590 inode->i_fop = &simple_dir_operations;
1594 * Must not load anything in the rbtree,
1595 * mpol_free_shared_policy will not be called.
1597 mpol_shared_policy_init(&info->policy, NULL);
1601 shmem_free_inode(sb);
1606 static const struct inode_operations shmem_symlink_inode_operations;
1607 static const struct inode_operations shmem_symlink_inline_operations;
1610 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1611 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1612 * below the loop driver, in the generic fashion that many filesystems support.
1614 static int shmem_readpage(struct file *file, struct page *page)
1616 struct inode *inode = page->mapping->host;
1617 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1623 shmem_write_begin(struct file *file, struct address_space *mapping,
1624 loff_t pos, unsigned len, unsigned flags,
1625 struct page **pagep, void **fsdata)
1627 struct inode *inode = mapping->host;
1628 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1630 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1634 shmem_write_end(struct file *file, struct address_space *mapping,
1635 loff_t pos, unsigned len, unsigned copied,
1636 struct page *page, void *fsdata)
1638 struct inode *inode = mapping->host;
1640 if (pos + copied > inode->i_size)
1641 i_size_write(inode, pos + copied);
1643 set_page_dirty(page);
1645 page_cache_release(page);
1650 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1652 struct inode *inode = filp->f_path.dentry->d_inode;
1653 struct address_space *mapping = inode->i_mapping;
1654 unsigned long index, offset;
1655 enum sgp_type sgp = SGP_READ;
1658 * Might this read be for a stacking filesystem? Then when reading
1659 * holes of a sparse file, we actually need to allocate those pages,
1660 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1662 if (segment_eq(get_fs(), KERNEL_DS))
1665 index = *ppos >> PAGE_CACHE_SHIFT;
1666 offset = *ppos & ~PAGE_CACHE_MASK;
1669 struct page *page = NULL;
1670 unsigned long end_index, nr, ret;
1671 loff_t i_size = i_size_read(inode);
1673 end_index = i_size >> PAGE_CACHE_SHIFT;
1674 if (index > end_index)
1676 if (index == end_index) {
1677 nr = i_size & ~PAGE_CACHE_MASK;
1682 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1684 if (desc->error == -EINVAL)
1692 * We must evaluate after, since reads (unlike writes)
1693 * are called without i_mutex protection against truncate
1695 nr = PAGE_CACHE_SIZE;
1696 i_size = i_size_read(inode);
1697 end_index = i_size >> PAGE_CACHE_SHIFT;
1698 if (index == end_index) {
1699 nr = i_size & ~PAGE_CACHE_MASK;
1702 page_cache_release(page);
1710 * If users can be writing to this page using arbitrary
1711 * virtual addresses, take care about potential aliasing
1712 * before reading the page on the kernel side.
1714 if (mapping_writably_mapped(mapping))
1715 flush_dcache_page(page);
1717 * Mark the page accessed if we read the beginning.
1720 mark_page_accessed(page);
1722 page = ZERO_PAGE(0);
1723 page_cache_get(page);
1727 * Ok, we have the page, and it's up-to-date, so
1728 * now we can copy it to user space...
1730 * The actor routine returns how many bytes were actually used..
1731 * NOTE! This may not be the same as how much of a user buffer
1732 * we filled up (we may be padding etc), so we can only update
1733 * "pos" here (the actor routine has to update the user buffer
1734 * pointers and the remaining count).
1736 ret = actor(desc, page, offset, nr);
1738 index += offset >> PAGE_CACHE_SHIFT;
1739 offset &= ~PAGE_CACHE_MASK;
1741 page_cache_release(page);
1742 if (ret != nr || !desc->count)
1748 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1749 file_accessed(filp);
1752 static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1753 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1755 struct file *filp = iocb->ki_filp;
1759 loff_t *ppos = &iocb->ki_pos;
1761 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1765 for (seg = 0; seg < nr_segs; seg++) {
1766 read_descriptor_t desc;
1769 desc.arg.buf = iov[seg].iov_base;
1770 desc.count = iov[seg].iov_len;
1771 if (desc.count == 0)
1774 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1775 retval += desc.written;
1777 retval = retval ?: desc.error;
1786 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1788 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1790 buf->f_type = TMPFS_MAGIC;
1791 buf->f_bsize = PAGE_CACHE_SIZE;
1792 buf->f_namelen = NAME_MAX;
1793 spin_lock(&sbinfo->stat_lock);
1794 if (sbinfo->max_blocks) {
1795 buf->f_blocks = sbinfo->max_blocks;
1796 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1798 if (sbinfo->max_inodes) {
1799 buf->f_files = sbinfo->max_inodes;
1800 buf->f_ffree = sbinfo->free_inodes;
1802 /* else leave those fields 0 like simple_statfs */
1803 spin_unlock(&sbinfo->stat_lock);
1808 * File creation. Allocate an inode, and we're done..
1811 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1813 struct inode *inode;
1814 int error = -ENOSPC;
1816 inode = shmem_get_inode(dir->i_sb, mode, dev, VM_NORESERVE);
1818 error = security_inode_init_security(inode, dir, NULL, NULL,
1821 if (error != -EOPNOTSUPP) {
1826 error = shmem_acl_init(inode, dir);
1831 if (dir->i_mode & S_ISGID) {
1832 inode->i_gid = dir->i_gid;
1834 inode->i_mode |= S_ISGID;
1836 dir->i_size += BOGO_DIRENT_SIZE;
1837 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1838 d_instantiate(dentry, inode);
1839 dget(dentry); /* Extra count - pin the dentry in core */
1844 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1848 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1854 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1855 struct nameidata *nd)
1857 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1863 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1865 struct inode *inode = old_dentry->d_inode;
1869 * No ordinary (disk based) filesystem counts links as inodes;
1870 * but each new link needs a new dentry, pinning lowmem, and
1871 * tmpfs dentries cannot be pruned until they are unlinked.
1873 ret = shmem_reserve_inode(inode->i_sb);
1877 dir->i_size += BOGO_DIRENT_SIZE;
1878 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1880 atomic_inc(&inode->i_count); /* New dentry reference */
1881 dget(dentry); /* Extra pinning count for the created dentry */
1882 d_instantiate(dentry, inode);
1887 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1889 struct inode *inode = dentry->d_inode;
1891 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1892 shmem_free_inode(inode->i_sb);
1894 dir->i_size -= BOGO_DIRENT_SIZE;
1895 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1897 dput(dentry); /* Undo the count from "create" - this does all the work */
1901 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1903 if (!simple_empty(dentry))
1906 drop_nlink(dentry->d_inode);
1908 return shmem_unlink(dir, dentry);
1912 * The VFS layer already does all the dentry stuff for rename,
1913 * we just have to decrement the usage count for the target if
1914 * it exists so that the VFS layer correctly free's it when it
1917 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1919 struct inode *inode = old_dentry->d_inode;
1920 int they_are_dirs = S_ISDIR(inode->i_mode);
1922 if (!simple_empty(new_dentry))
1925 if (new_dentry->d_inode) {
1926 (void) shmem_unlink(new_dir, new_dentry);
1928 drop_nlink(old_dir);
1929 } else if (they_are_dirs) {
1930 drop_nlink(old_dir);
1934 old_dir->i_size -= BOGO_DIRENT_SIZE;
1935 new_dir->i_size += BOGO_DIRENT_SIZE;
1936 old_dir->i_ctime = old_dir->i_mtime =
1937 new_dir->i_ctime = new_dir->i_mtime =
1938 inode->i_ctime = CURRENT_TIME;
1942 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1946 struct inode *inode;
1947 struct page *page = NULL;
1949 struct shmem_inode_info *info;
1951 len = strlen(symname) + 1;
1952 if (len > PAGE_CACHE_SIZE)
1953 return -ENAMETOOLONG;
1955 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
1959 error = security_inode_init_security(inode, dir, NULL, NULL,
1962 if (error != -EOPNOTSUPP) {
1969 info = SHMEM_I(inode);
1970 inode->i_size = len-1;
1971 if (len <= (char *)inode - (char *)info) {
1973 memcpy(info, symname, len);
1974 inode->i_op = &shmem_symlink_inline_operations;
1976 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1981 inode->i_mapping->a_ops = &shmem_aops;
1982 inode->i_op = &shmem_symlink_inode_operations;
1983 kaddr = kmap_atomic(page, KM_USER0);
1984 memcpy(kaddr, symname, len);
1985 kunmap_atomic(kaddr, KM_USER0);
1986 set_page_dirty(page);
1988 page_cache_release(page);
1990 if (dir->i_mode & S_ISGID)
1991 inode->i_gid = dir->i_gid;
1992 dir->i_size += BOGO_DIRENT_SIZE;
1993 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1994 d_instantiate(dentry, inode);
1999 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
2001 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
2005 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
2007 struct page *page = NULL;
2008 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2009 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
2015 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2017 if (!IS_ERR(nd_get_link(nd))) {
2018 struct page *page = cookie;
2020 mark_page_accessed(page);
2021 page_cache_release(page);
2025 static const struct inode_operations shmem_symlink_inline_operations = {
2026 .readlink = generic_readlink,
2027 .follow_link = shmem_follow_link_inline,
2030 static const struct inode_operations shmem_symlink_inode_operations = {
2031 .truncate = shmem_truncate,
2032 .readlink = generic_readlink,
2033 .follow_link = shmem_follow_link,
2034 .put_link = shmem_put_link,
2037 #ifdef CONFIG_TMPFS_POSIX_ACL
2039 * Superblocks without xattr inode operations will get security.* xattr
2040 * support from the VFS "for free". As soon as we have any other xattrs
2041 * like ACLs, we also need to implement the security.* handlers at
2042 * filesystem level, though.
2045 static size_t shmem_xattr_security_list(struct inode *inode, char *list,
2046 size_t list_len, const char *name,
2049 return security_inode_listsecurity(inode, list, list_len);
2052 static int shmem_xattr_security_get(struct inode *inode, const char *name,
2053 void *buffer, size_t size)
2055 if (strcmp(name, "") == 0)
2057 return xattr_getsecurity(inode, name, buffer, size);
2060 static int shmem_xattr_security_set(struct inode *inode, const char *name,
2061 const void *value, size_t size, int flags)
2063 if (strcmp(name, "") == 0)
2065 return security_inode_setsecurity(inode, name, value, size, flags);
2068 static struct xattr_handler shmem_xattr_security_handler = {
2069 .prefix = XATTR_SECURITY_PREFIX,
2070 .list = shmem_xattr_security_list,
2071 .get = shmem_xattr_security_get,
2072 .set = shmem_xattr_security_set,
2075 static struct xattr_handler *shmem_xattr_handlers[] = {
2076 &shmem_xattr_acl_access_handler,
2077 &shmem_xattr_acl_default_handler,
2078 &shmem_xattr_security_handler,
2083 static struct dentry *shmem_get_parent(struct dentry *child)
2085 return ERR_PTR(-ESTALE);
2088 static int shmem_match(struct inode *ino, void *vfh)
2092 inum = (inum << 32) | fh[1];
2093 return ino->i_ino == inum && fh[0] == ino->i_generation;
2096 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2097 struct fid *fid, int fh_len, int fh_type)
2099 struct inode *inode;
2100 struct dentry *dentry = NULL;
2101 u64 inum = fid->raw[2];
2102 inum = (inum << 32) | fid->raw[1];
2107 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2108 shmem_match, fid->raw);
2110 dentry = d_find_alias(inode);
2117 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2120 struct inode *inode = dentry->d_inode;
2125 if (hlist_unhashed(&inode->i_hash)) {
2126 /* Unfortunately insert_inode_hash is not idempotent,
2127 * so as we hash inodes here rather than at creation
2128 * time, we need a lock to ensure we only try
2131 static DEFINE_SPINLOCK(lock);
2133 if (hlist_unhashed(&inode->i_hash))
2134 __insert_inode_hash(inode,
2135 inode->i_ino + inode->i_generation);
2139 fh[0] = inode->i_generation;
2140 fh[1] = inode->i_ino;
2141 fh[2] = ((__u64)inode->i_ino) >> 32;
2147 static const struct export_operations shmem_export_ops = {
2148 .get_parent = shmem_get_parent,
2149 .encode_fh = shmem_encode_fh,
2150 .fh_to_dentry = shmem_fh_to_dentry,
2153 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2156 char *this_char, *value, *rest;
2158 while (options != NULL) {
2159 this_char = options;
2162 * NUL-terminate this option: unfortunately,
2163 * mount options form a comma-separated list,
2164 * but mpol's nodelist may also contain commas.
2166 options = strchr(options, ',');
2167 if (options == NULL)
2170 if (!isdigit(*options)) {
2177 if ((value = strchr(this_char,'=')) != NULL) {
2181 "tmpfs: No value for mount option '%s'\n",
2186 if (!strcmp(this_char,"size")) {
2187 unsigned long long size;
2188 size = memparse(value,&rest);
2190 size <<= PAGE_SHIFT;
2191 size *= totalram_pages;
2197 sbinfo->max_blocks =
2198 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2199 } else if (!strcmp(this_char,"nr_blocks")) {
2200 sbinfo->max_blocks = memparse(value, &rest);
2203 } else if (!strcmp(this_char,"nr_inodes")) {
2204 sbinfo->max_inodes = memparse(value, &rest);
2207 } else if (!strcmp(this_char,"mode")) {
2210 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2213 } else if (!strcmp(this_char,"uid")) {
2216 sbinfo->uid = simple_strtoul(value, &rest, 0);
2219 } else if (!strcmp(this_char,"gid")) {
2222 sbinfo->gid = simple_strtoul(value, &rest, 0);
2225 } else if (!strcmp(this_char,"mpol")) {
2226 if (mpol_parse_str(value, &sbinfo->mpol, 1))
2229 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2237 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2243 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2245 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2246 struct shmem_sb_info config = *sbinfo;
2247 unsigned long blocks;
2248 unsigned long inodes;
2249 int error = -EINVAL;
2251 if (shmem_parse_options(data, &config, true))
2254 spin_lock(&sbinfo->stat_lock);
2255 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2256 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2257 if (config.max_blocks < blocks)
2259 if (config.max_inodes < inodes)
2262 * Those tests also disallow limited->unlimited while any are in
2263 * use, so i_blocks will always be zero when max_blocks is zero;
2264 * but we must separately disallow unlimited->limited, because
2265 * in that case we have no record of how much is already in use.
2267 if (config.max_blocks && !sbinfo->max_blocks)
2269 if (config.max_inodes && !sbinfo->max_inodes)
2273 sbinfo->max_blocks = config.max_blocks;
2274 sbinfo->free_blocks = config.max_blocks - blocks;
2275 sbinfo->max_inodes = config.max_inodes;
2276 sbinfo->free_inodes = config.max_inodes - inodes;
2278 mpol_put(sbinfo->mpol);
2279 sbinfo->mpol = config.mpol; /* transfers initial ref */
2281 spin_unlock(&sbinfo->stat_lock);
2285 static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2287 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2289 if (sbinfo->max_blocks != shmem_default_max_blocks())
2290 seq_printf(seq, ",size=%luk",
2291 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2292 if (sbinfo->max_inodes != shmem_default_max_inodes())
2293 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2294 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2295 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2296 if (sbinfo->uid != 0)
2297 seq_printf(seq, ",uid=%u", sbinfo->uid);
2298 if (sbinfo->gid != 0)
2299 seq_printf(seq, ",gid=%u", sbinfo->gid);
2300 shmem_show_mpol(seq, sbinfo->mpol);
2303 #endif /* CONFIG_TMPFS */
2305 static void shmem_put_super(struct super_block *sb)
2307 kfree(sb->s_fs_info);
2308 sb->s_fs_info = NULL;
2311 int shmem_fill_super(struct super_block *sb, void *data, int silent)
2313 struct inode *inode;
2314 struct dentry *root;
2315 struct shmem_sb_info *sbinfo;
2318 /* Round up to L1_CACHE_BYTES to resist false sharing */
2319 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2320 L1_CACHE_BYTES), GFP_KERNEL);
2324 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2325 sbinfo->uid = current_fsuid();
2326 sbinfo->gid = current_fsgid();
2327 sb->s_fs_info = sbinfo;
2331 * Per default we only allow half of the physical ram per
2332 * tmpfs instance, limiting inodes to one per page of lowmem;
2333 * but the internal instance is left unlimited.
2335 if (!(sb->s_flags & MS_NOUSER)) {
2336 sbinfo->max_blocks = shmem_default_max_blocks();
2337 sbinfo->max_inodes = shmem_default_max_inodes();
2338 if (shmem_parse_options(data, sbinfo, false)) {
2343 sb->s_export_op = &shmem_export_ops;
2345 sb->s_flags |= MS_NOUSER;
2348 spin_lock_init(&sbinfo->stat_lock);
2349 sbinfo->free_blocks = sbinfo->max_blocks;
2350 sbinfo->free_inodes = sbinfo->max_inodes;
2352 sb->s_maxbytes = SHMEM_MAX_BYTES;
2353 sb->s_blocksize = PAGE_CACHE_SIZE;
2354 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2355 sb->s_magic = TMPFS_MAGIC;
2356 sb->s_op = &shmem_ops;
2357 sb->s_time_gran = 1;
2358 #ifdef CONFIG_TMPFS_POSIX_ACL
2359 sb->s_xattr = shmem_xattr_handlers;
2360 sb->s_flags |= MS_POSIXACL;
2363 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2366 inode->i_uid = sbinfo->uid;
2367 inode->i_gid = sbinfo->gid;
2368 root = d_alloc_root(inode);
2377 shmem_put_super(sb);
2381 static struct kmem_cache *shmem_inode_cachep;
2383 static struct inode *shmem_alloc_inode(struct super_block *sb)
2385 struct shmem_inode_info *p;
2386 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2389 return &p->vfs_inode;
2392 static void shmem_destroy_inode(struct inode *inode)
2394 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2395 /* only struct inode is valid if it's an inline symlink */
2396 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2398 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2401 static void init_once(void *foo)
2403 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2405 inode_init_once(&p->vfs_inode);
2408 static int init_inodecache(void)
2410 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2411 sizeof(struct shmem_inode_info),
2412 0, SLAB_PANIC, init_once);
2416 static void destroy_inodecache(void)
2418 kmem_cache_destroy(shmem_inode_cachep);
2421 static const struct address_space_operations shmem_aops = {
2422 .writepage = shmem_writepage,
2423 .set_page_dirty = __set_page_dirty_no_writeback,
2425 .readpage = shmem_readpage,
2426 .write_begin = shmem_write_begin,
2427 .write_end = shmem_write_end,
2429 .migratepage = migrate_page,
2430 .error_remove_page = generic_error_remove_page,
2433 static const struct file_operations shmem_file_operations = {
2436 .llseek = generic_file_llseek,
2437 .read = do_sync_read,
2438 .write = do_sync_write,
2439 .aio_read = shmem_file_aio_read,
2440 .aio_write = generic_file_aio_write,
2441 .fsync = simple_sync_file,
2442 .splice_read = generic_file_splice_read,
2443 .splice_write = generic_file_splice_write,
2447 static const struct inode_operations shmem_inode_operations = {
2448 .truncate = shmem_truncate,
2449 .setattr = shmem_notify_change,
2450 .truncate_range = shmem_truncate_range,
2451 #ifdef CONFIG_TMPFS_POSIX_ACL
2452 .setxattr = generic_setxattr,
2453 .getxattr = generic_getxattr,
2454 .listxattr = generic_listxattr,
2455 .removexattr = generic_removexattr,
2456 .check_acl = shmem_check_acl,
2461 static const struct inode_operations shmem_dir_inode_operations = {
2463 .create = shmem_create,
2464 .lookup = simple_lookup,
2466 .unlink = shmem_unlink,
2467 .symlink = shmem_symlink,
2468 .mkdir = shmem_mkdir,
2469 .rmdir = shmem_rmdir,
2470 .mknod = shmem_mknod,
2471 .rename = shmem_rename,
2473 #ifdef CONFIG_TMPFS_POSIX_ACL
2474 .setattr = shmem_notify_change,
2475 .setxattr = generic_setxattr,
2476 .getxattr = generic_getxattr,
2477 .listxattr = generic_listxattr,
2478 .removexattr = generic_removexattr,
2479 .check_acl = shmem_check_acl,
2483 static const struct inode_operations shmem_special_inode_operations = {
2484 #ifdef CONFIG_TMPFS_POSIX_ACL
2485 .setattr = shmem_notify_change,
2486 .setxattr = generic_setxattr,
2487 .getxattr = generic_getxattr,
2488 .listxattr = generic_listxattr,
2489 .removexattr = generic_removexattr,
2490 .check_acl = shmem_check_acl,
2494 static const struct super_operations shmem_ops = {
2495 .alloc_inode = shmem_alloc_inode,
2496 .destroy_inode = shmem_destroy_inode,
2498 .statfs = shmem_statfs,
2499 .remount_fs = shmem_remount_fs,
2500 .show_options = shmem_show_options,
2502 .delete_inode = shmem_delete_inode,
2503 .drop_inode = generic_delete_inode,
2504 .put_super = shmem_put_super,
2507 static const struct vm_operations_struct shmem_vm_ops = {
2508 .fault = shmem_fault,
2510 .set_policy = shmem_set_policy,
2511 .get_policy = shmem_get_policy,
2516 static int shmem_get_sb(struct file_system_type *fs_type,
2517 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
2519 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
2522 static struct file_system_type tmpfs_fs_type = {
2523 .owner = THIS_MODULE,
2525 .get_sb = shmem_get_sb,
2526 .kill_sb = kill_litter_super,
2529 int __init init_tmpfs(void)
2533 error = bdi_init(&shmem_backing_dev_info);
2537 error = init_inodecache();
2541 error = register_filesystem(&tmpfs_fs_type);
2543 printk(KERN_ERR "Could not register tmpfs\n");
2547 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2548 tmpfs_fs_type.name, NULL);
2549 if (IS_ERR(shm_mnt)) {
2550 error = PTR_ERR(shm_mnt);
2551 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2557 unregister_filesystem(&tmpfs_fs_type);
2559 destroy_inodecache();
2561 bdi_destroy(&shmem_backing_dev_info);
2563 shm_mnt = ERR_PTR(error);
2567 #else /* !CONFIG_SHMEM */
2570 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2572 * This is intended for small system where the benefits of the full
2573 * shmem code (swap-backed and resource-limited) are outweighed by
2574 * their complexity. On systems without swap this code should be
2575 * effectively equivalent, but much lighter weight.
2578 #include <linux/ramfs.h>
2580 static struct file_system_type tmpfs_fs_type = {
2582 .get_sb = ramfs_get_sb,
2583 .kill_sb = kill_litter_super,
2586 int __init init_tmpfs(void)
2588 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2590 shm_mnt = kern_mount(&tmpfs_fs_type);
2591 BUG_ON(IS_ERR(shm_mnt));
2596 int shmem_unuse(swp_entry_t entry, struct page *page)
2601 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2606 #define shmem_vm_ops generic_file_vm_ops
2607 #define shmem_file_operations ramfs_file_operations
2608 #define shmem_get_inode(sb, mode, dev, flags) ramfs_get_inode(sb, mode, dev)
2609 #define shmem_acct_size(flags, size) 0
2610 #define shmem_unacct_size(flags, size) do {} while (0)
2611 #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
2613 #endif /* CONFIG_SHMEM */
2618 * shmem_file_setup - get an unlinked file living in tmpfs
2619 * @name: name for dentry (to be seen in /proc/<pid>/maps
2620 * @size: size to be set for the file
2621 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2623 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2627 struct inode *inode;
2629 struct dentry *root;
2632 if (IS_ERR(shm_mnt))
2633 return (void *)shm_mnt;
2635 if (size < 0 || size > SHMEM_MAX_BYTES)
2636 return ERR_PTR(-EINVAL);
2638 if (shmem_acct_size(flags, size))
2639 return ERR_PTR(-ENOMEM);
2643 this.len = strlen(name);
2644 this.hash = 0; /* will go */
2645 root = shm_mnt->mnt_root;
2646 path.dentry = d_alloc(root, &this);
2649 path.mnt = mntget(shm_mnt);
2652 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags);
2656 d_instantiate(path.dentry, inode);
2657 inode->i_size = size;
2658 inode->i_nlink = 0; /* It is unlinked */
2660 error = ramfs_nommu_expand_for_mapping(inode, size);
2666 file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2667 &shmem_file_operations);
2676 shmem_unacct_size(flags, size);
2677 return ERR_PTR(error);
2679 EXPORT_SYMBOL_GPL(shmem_file_setup);
2682 * shmem_zero_setup - setup a shared anonymous mapping
2683 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2685 int shmem_zero_setup(struct vm_area_struct *vma)
2688 loff_t size = vma->vm_end - vma->vm_start;
2690 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2692 return PTR_ERR(file);
2696 vma->vm_file = file;
2697 vma->vm_ops = &shmem_vm_ops;