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>
17 * This file is released under the GPL.
21 * This virtual memory filesystem is heavily based on the ramfs. It
22 * extends ramfs by the ability to use swap and honor resource limits
23 * which makes it a completely usable filesystem.
26 #include <linux/module.h>
27 #include <linux/init.h>
29 #include <linux/xattr.h>
30 #include <linux/exportfs.h>
31 #include <linux/generic_acl.h>
33 #include <linux/mman.h>
34 #include <linux/file.h>
35 #include <linux/swap.h>
36 #include <linux/pagemap.h>
37 #include <linux/string.h>
38 #include <linux/slab.h>
39 #include <linux/backing-dev.h>
40 #include <linux/shmem_fs.h>
41 #include <linux/mount.h>
42 #include <linux/writeback.h>
43 #include <linux/vfs.h>
44 #include <linux/blkdev.h>
45 #include <linux/security.h>
46 #include <linux/swapops.h>
47 #include <linux/mempolicy.h>
48 #include <linux/namei.h>
49 #include <linux/ctype.h>
50 #include <linux/migrate.h>
51 #include <linux/highmem.h>
53 #include <asm/uaccess.h>
54 #include <asm/div64.h>
55 #include <asm/pgtable.h>
57 /* This magic number is used in glibc for posix shared memory */
58 #define TMPFS_MAGIC 0x01021994
60 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
61 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
62 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
64 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
65 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
67 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
69 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
70 #define SHMEM_PAGEIN VM_READ
71 #define SHMEM_TRUNCATE VM_WRITE
73 /* Definition to limit shmem_truncate's steps between cond_rescheds */
74 #define LATENCY_LIMIT 64
76 /* Pretend that each entry is of this size in directory's i_size */
77 #define BOGO_DIRENT_SIZE 20
79 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
81 SGP_READ, /* don't exceed i_size, don't allocate page */
82 SGP_CACHE, /* don't exceed i_size, may allocate page */
83 SGP_WRITE, /* may exceed i_size, may allocate page */
86 static int shmem_getpage(struct inode *inode, unsigned long idx,
87 struct page **pagep, enum sgp_type sgp, int *type);
89 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
92 * The above definition of ENTRIES_PER_PAGE, and the use of
93 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
94 * might be reconsidered if it ever diverges from PAGE_SIZE.
96 * Mobility flags are masked out as swap vectors cannot move
98 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
99 PAGE_CACHE_SHIFT-PAGE_SHIFT);
102 static inline void shmem_dir_free(struct page *page)
104 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
107 static struct page **shmem_dir_map(struct page *page)
109 return (struct page **)kmap_atomic(page, KM_USER0);
112 static inline void shmem_dir_unmap(struct page **dir)
114 kunmap_atomic(dir, KM_USER0);
117 static swp_entry_t *shmem_swp_map(struct page *page)
119 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
122 static inline void shmem_swp_balance_unmap(void)
125 * When passing a pointer to an i_direct entry, to code which
126 * also handles indirect entries and so will shmem_swp_unmap,
127 * we must arrange for the preempt count to remain in balance.
128 * What kmap_atomic of a lowmem page does depends on config
129 * and architecture, so pretend to kmap_atomic some lowmem page.
131 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
134 static inline void shmem_swp_unmap(swp_entry_t *entry)
136 kunmap_atomic(entry, KM_USER1);
139 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
141 return sb->s_fs_info;
145 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
146 * for shared memory and for shared anonymous (/dev/zero) mappings
147 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
148 * consistent with the pre-accounting of private mappings ...
150 static inline int shmem_acct_size(unsigned long flags, loff_t size)
152 return (flags & VM_ACCOUNT)?
153 security_vm_enough_memory(VM_ACCT(size)): 0;
156 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
158 if (flags & VM_ACCOUNT)
159 vm_unacct_memory(VM_ACCT(size));
163 * ... whereas tmpfs objects are accounted incrementally as
164 * pages are allocated, in order to allow huge sparse files.
165 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
166 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
168 static inline int shmem_acct_block(unsigned long flags)
170 return (flags & VM_ACCOUNT)?
171 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
174 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
176 if (!(flags & VM_ACCOUNT))
177 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
180 static const struct super_operations shmem_ops;
181 static const struct address_space_operations shmem_aops;
182 static const struct file_operations shmem_file_operations;
183 static const struct inode_operations shmem_inode_operations;
184 static const struct inode_operations shmem_dir_inode_operations;
185 static const struct inode_operations shmem_special_inode_operations;
186 static struct vm_operations_struct shmem_vm_ops;
188 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
189 .ra_pages = 0, /* No readahead */
190 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
191 .unplug_io_fn = default_unplug_io_fn,
194 static LIST_HEAD(shmem_swaplist);
195 static DEFINE_SPINLOCK(shmem_swaplist_lock);
197 static void shmem_free_blocks(struct inode *inode, long pages)
199 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
200 if (sbinfo->max_blocks) {
201 spin_lock(&sbinfo->stat_lock);
202 sbinfo->free_blocks += pages;
203 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
204 spin_unlock(&sbinfo->stat_lock);
208 static int shmem_reserve_inode(struct super_block *sb)
210 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
211 if (sbinfo->max_inodes) {
212 spin_lock(&sbinfo->stat_lock);
213 if (!sbinfo->free_inodes) {
214 spin_unlock(&sbinfo->stat_lock);
217 sbinfo->free_inodes--;
218 spin_unlock(&sbinfo->stat_lock);
223 static void shmem_free_inode(struct super_block *sb)
225 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
226 if (sbinfo->max_inodes) {
227 spin_lock(&sbinfo->stat_lock);
228 sbinfo->free_inodes++;
229 spin_unlock(&sbinfo->stat_lock);
234 * shmem_recalc_inode - recalculate the size of an inode
236 * @inode: inode to recalc
238 * We have to calculate the free blocks since the mm can drop
239 * undirtied hole pages behind our back.
241 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
242 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
244 * It has to be called with the spinlock held.
246 static void shmem_recalc_inode(struct inode *inode)
248 struct shmem_inode_info *info = SHMEM_I(inode);
251 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
253 info->alloced -= freed;
254 shmem_unacct_blocks(info->flags, freed);
255 shmem_free_blocks(inode, freed);
260 * shmem_swp_entry - find the swap vector position in the info structure
262 * @info: info structure for the inode
263 * @index: index of the page to find
264 * @page: optional page to add to the structure. Has to be preset to
267 * If there is no space allocated yet it will return NULL when
268 * page is NULL, else it will use the page for the needed block,
269 * setting it to NULL on return to indicate that it has been used.
271 * The swap vector is organized the following way:
273 * There are SHMEM_NR_DIRECT entries directly stored in the
274 * shmem_inode_info structure. So small files do not need an addional
277 * For pages with index > SHMEM_NR_DIRECT there is the pointer
278 * i_indirect which points to a page which holds in the first half
279 * doubly indirect blocks, in the second half triple indirect blocks:
281 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
282 * following layout (for SHMEM_NR_DIRECT == 16):
284 * i_indirect -> dir --> 16-19
297 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
299 unsigned long offset;
303 if (index < SHMEM_NR_DIRECT) {
304 shmem_swp_balance_unmap();
305 return info->i_direct+index;
307 if (!info->i_indirect) {
309 info->i_indirect = *page;
312 return NULL; /* need another page */
315 index -= SHMEM_NR_DIRECT;
316 offset = index % ENTRIES_PER_PAGE;
317 index /= ENTRIES_PER_PAGE;
318 dir = shmem_dir_map(info->i_indirect);
320 if (index >= ENTRIES_PER_PAGE/2) {
321 index -= ENTRIES_PER_PAGE/2;
322 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
323 index %= ENTRIES_PER_PAGE;
330 shmem_dir_unmap(dir);
331 return NULL; /* need another page */
333 shmem_dir_unmap(dir);
334 dir = shmem_dir_map(subdir);
340 if (!page || !(subdir = *page)) {
341 shmem_dir_unmap(dir);
342 return NULL; /* need a page */
347 shmem_dir_unmap(dir);
348 return shmem_swp_map(subdir) + offset;
351 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
353 long incdec = value? 1: -1;
356 info->swapped += incdec;
357 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
358 struct page *page = kmap_atomic_to_page(entry);
359 set_page_private(page, page_private(page) + incdec);
364 * shmem_swp_alloc - get the position of the swap entry for the page.
365 * If it does not exist allocate the entry.
367 * @info: info structure for the inode
368 * @index: index of the page to find
369 * @sgp: check and recheck i_size? skip allocation?
371 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
373 struct inode *inode = &info->vfs_inode;
374 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
375 struct page *page = NULL;
378 if (sgp != SGP_WRITE &&
379 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
380 return ERR_PTR(-EINVAL);
382 while (!(entry = shmem_swp_entry(info, index, &page))) {
384 return shmem_swp_map(ZERO_PAGE(0));
386 * Test free_blocks against 1 not 0, since we have 1 data
387 * page (and perhaps indirect index pages) yet to allocate:
388 * a waste to allocate index if we cannot allocate data.
390 if (sbinfo->max_blocks) {
391 spin_lock(&sbinfo->stat_lock);
392 if (sbinfo->free_blocks <= 1) {
393 spin_unlock(&sbinfo->stat_lock);
394 return ERR_PTR(-ENOSPC);
396 sbinfo->free_blocks--;
397 inode->i_blocks += BLOCKS_PER_PAGE;
398 spin_unlock(&sbinfo->stat_lock);
401 spin_unlock(&info->lock);
402 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
404 set_page_private(page, 0);
405 spin_lock(&info->lock);
408 shmem_free_blocks(inode, 1);
409 return ERR_PTR(-ENOMEM);
411 if (sgp != SGP_WRITE &&
412 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
413 entry = ERR_PTR(-EINVAL);
416 if (info->next_index <= index)
417 info->next_index = index + 1;
420 /* another task gave its page, or truncated the file */
421 shmem_free_blocks(inode, 1);
422 shmem_dir_free(page);
424 if (info->next_index <= index && !IS_ERR(entry))
425 info->next_index = index + 1;
430 * shmem_free_swp - free some swap entries in a directory
432 * @dir: pointer to the directory
433 * @edir: pointer after last entry of the directory
434 * @punch_lock: pointer to spinlock when needed for the holepunch case
436 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
437 spinlock_t *punch_lock)
439 spinlock_t *punch_unlock = NULL;
443 for (ptr = dir; ptr < edir; ptr++) {
445 if (unlikely(punch_lock)) {
446 punch_unlock = punch_lock;
448 spin_lock(punch_unlock);
452 free_swap_and_cache(*ptr);
453 *ptr = (swp_entry_t){0};
458 spin_unlock(punch_unlock);
462 static int shmem_map_and_free_swp(struct page *subdir, int offset,
463 int limit, struct page ***dir, spinlock_t *punch_lock)
468 ptr = shmem_swp_map(subdir);
469 for (; offset < limit; offset += LATENCY_LIMIT) {
470 int size = limit - offset;
471 if (size > LATENCY_LIMIT)
472 size = LATENCY_LIMIT;
473 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
475 if (need_resched()) {
476 shmem_swp_unmap(ptr);
478 shmem_dir_unmap(*dir);
482 ptr = shmem_swp_map(subdir);
485 shmem_swp_unmap(ptr);
489 static void shmem_free_pages(struct list_head *next)
495 page = container_of(next, struct page, lru);
497 shmem_dir_free(page);
499 if (freed >= LATENCY_LIMIT) {
506 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
508 struct shmem_inode_info *info = SHMEM_I(inode);
513 unsigned long diroff;
519 LIST_HEAD(pages_to_free);
520 long nr_pages_to_free = 0;
521 long nr_swaps_freed = 0;
525 spinlock_t *needs_lock;
526 spinlock_t *punch_lock;
527 unsigned long upper_limit;
529 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
530 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
531 if (idx >= info->next_index)
534 spin_lock(&info->lock);
535 info->flags |= SHMEM_TRUNCATE;
536 if (likely(end == (loff_t) -1)) {
537 limit = info->next_index;
538 upper_limit = SHMEM_MAX_INDEX;
539 info->next_index = idx;
543 if (end + 1 >= inode->i_size) { /* we may free a little more */
544 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
546 upper_limit = SHMEM_MAX_INDEX;
548 limit = (end + 1) >> PAGE_CACHE_SHIFT;
551 needs_lock = &info->lock;
555 topdir = info->i_indirect;
556 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
557 info->i_indirect = NULL;
559 list_add(&topdir->lru, &pages_to_free);
561 spin_unlock(&info->lock);
563 if (info->swapped && idx < SHMEM_NR_DIRECT) {
564 ptr = info->i_direct;
566 if (size > SHMEM_NR_DIRECT)
567 size = SHMEM_NR_DIRECT;
568 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
572 * If there are no indirect blocks or we are punching a hole
573 * below indirect blocks, nothing to be done.
575 if (!topdir || limit <= SHMEM_NR_DIRECT)
579 * The truncation case has already dropped info->lock, and we're safe
580 * because i_size and next_index have already been lowered, preventing
581 * access beyond. But in the punch_hole case, we still need to take
582 * the lock when updating the swap directory, because there might be
583 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
584 * shmem_writepage. However, whenever we find we can remove a whole
585 * directory page (not at the misaligned start or end of the range),
586 * we first NULLify its pointer in the level above, and then have no
587 * need to take the lock when updating its contents: needs_lock and
588 * punch_lock (either pointing to info->lock or NULL) manage this.
591 upper_limit -= SHMEM_NR_DIRECT;
592 limit -= SHMEM_NR_DIRECT;
593 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
594 offset = idx % ENTRIES_PER_PAGE;
597 dir = shmem_dir_map(topdir);
598 stage = ENTRIES_PER_PAGEPAGE/2;
599 if (idx < ENTRIES_PER_PAGEPAGE/2) {
601 diroff = idx/ENTRIES_PER_PAGE;
603 dir += ENTRIES_PER_PAGE/2;
604 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
606 stage += ENTRIES_PER_PAGEPAGE;
609 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
610 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
611 if (!diroff && !offset && upper_limit >= stage) {
613 spin_lock(needs_lock);
615 spin_unlock(needs_lock);
620 list_add(&middir->lru, &pages_to_free);
622 shmem_dir_unmap(dir);
623 dir = shmem_dir_map(middir);
631 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
632 if (unlikely(idx == stage)) {
633 shmem_dir_unmap(dir);
634 dir = shmem_dir_map(topdir) +
635 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
638 idx += ENTRIES_PER_PAGEPAGE;
642 stage = idx + ENTRIES_PER_PAGEPAGE;
645 needs_lock = &info->lock;
646 if (upper_limit >= stage) {
648 spin_lock(needs_lock);
650 spin_unlock(needs_lock);
655 list_add(&middir->lru, &pages_to_free);
657 shmem_dir_unmap(dir);
659 dir = shmem_dir_map(middir);
662 punch_lock = needs_lock;
663 subdir = dir[diroff];
664 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
666 spin_lock(needs_lock);
668 spin_unlock(needs_lock);
673 list_add(&subdir->lru, &pages_to_free);
675 if (subdir && page_private(subdir) /* has swap entries */) {
677 if (size > ENTRIES_PER_PAGE)
678 size = ENTRIES_PER_PAGE;
679 freed = shmem_map_and_free_swp(subdir,
680 offset, size, &dir, punch_lock);
682 dir = shmem_dir_map(middir);
683 nr_swaps_freed += freed;
684 if (offset || punch_lock) {
685 spin_lock(&info->lock);
686 set_page_private(subdir,
687 page_private(subdir) - freed);
688 spin_unlock(&info->lock);
690 BUG_ON(page_private(subdir) != freed);
695 shmem_dir_unmap(dir);
697 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
699 * Call truncate_inode_pages again: racing shmem_unuse_inode
700 * may have swizzled a page in from swap since vmtruncate or
701 * generic_delete_inode did it, before we lowered next_index.
702 * Also, though shmem_getpage checks i_size before adding to
703 * cache, no recheck after: so fix the narrow window there too.
705 * Recalling truncate_inode_pages_range and unmap_mapping_range
706 * every time for punch_hole (which never got a chance to clear
707 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
708 * yet hardly ever necessary: try to optimize them out later.
710 truncate_inode_pages_range(inode->i_mapping, start, end);
712 unmap_mapping_range(inode->i_mapping, start,
716 spin_lock(&info->lock);
717 info->flags &= ~SHMEM_TRUNCATE;
718 info->swapped -= nr_swaps_freed;
719 if (nr_pages_to_free)
720 shmem_free_blocks(inode, nr_pages_to_free);
721 shmem_recalc_inode(inode);
722 spin_unlock(&info->lock);
725 * Empty swap vector directory pages to be freed?
727 if (!list_empty(&pages_to_free)) {
728 pages_to_free.prev->next = NULL;
729 shmem_free_pages(pages_to_free.next);
733 static void shmem_truncate(struct inode *inode)
735 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
738 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
740 struct inode *inode = dentry->d_inode;
741 struct page *page = NULL;
744 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
745 if (attr->ia_size < inode->i_size) {
747 * If truncating down to a partial page, then
748 * if that page is already allocated, hold it
749 * in memory until the truncation is over, so
750 * truncate_partial_page cannnot miss it were
751 * it assigned to swap.
753 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
754 (void) shmem_getpage(inode,
755 attr->ia_size>>PAGE_CACHE_SHIFT,
756 &page, SGP_READ, NULL);
761 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
762 * detect if any pages might have been added to cache
763 * after truncate_inode_pages. But we needn't bother
764 * if it's being fully truncated to zero-length: the
765 * nrpages check is efficient enough in that case.
768 struct shmem_inode_info *info = SHMEM_I(inode);
769 spin_lock(&info->lock);
770 info->flags &= ~SHMEM_PAGEIN;
771 spin_unlock(&info->lock);
776 error = inode_change_ok(inode, attr);
778 error = inode_setattr(inode, attr);
779 #ifdef CONFIG_TMPFS_POSIX_ACL
780 if (!error && (attr->ia_valid & ATTR_MODE))
781 error = generic_acl_chmod(inode, &shmem_acl_ops);
784 page_cache_release(page);
788 static void shmem_delete_inode(struct inode *inode)
790 struct shmem_inode_info *info = SHMEM_I(inode);
792 if (inode->i_op->truncate == shmem_truncate) {
793 truncate_inode_pages(inode->i_mapping, 0);
794 shmem_unacct_size(info->flags, inode->i_size);
796 shmem_truncate(inode);
797 if (!list_empty(&info->swaplist)) {
798 spin_lock(&shmem_swaplist_lock);
799 list_del_init(&info->swaplist);
800 spin_unlock(&shmem_swaplist_lock);
803 BUG_ON(inode->i_blocks);
804 shmem_free_inode(inode->i_sb);
808 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
812 for (ptr = dir; ptr < edir; ptr++) {
813 if (ptr->val == entry.val)
819 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
833 ptr = info->i_direct;
834 spin_lock(&info->lock);
835 limit = info->next_index;
837 if (size > SHMEM_NR_DIRECT)
838 size = SHMEM_NR_DIRECT;
839 offset = shmem_find_swp(entry, ptr, ptr+size);
841 shmem_swp_balance_unmap();
844 if (!info->i_indirect)
847 dir = shmem_dir_map(info->i_indirect);
848 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
850 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
851 if (unlikely(idx == stage)) {
852 shmem_dir_unmap(dir-1);
853 dir = shmem_dir_map(info->i_indirect) +
854 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
857 idx += ENTRIES_PER_PAGEPAGE;
861 stage = idx + ENTRIES_PER_PAGEPAGE;
863 shmem_dir_unmap(dir);
864 dir = shmem_dir_map(subdir);
867 if (subdir && page_private(subdir)) {
868 ptr = shmem_swp_map(subdir);
870 if (size > ENTRIES_PER_PAGE)
871 size = ENTRIES_PER_PAGE;
872 offset = shmem_find_swp(entry, ptr, ptr+size);
874 shmem_dir_unmap(dir);
877 shmem_swp_unmap(ptr);
881 shmem_dir_unmap(dir-1);
883 spin_unlock(&info->lock);
887 inode = &info->vfs_inode;
888 error = add_to_page_cache(page, inode->i_mapping, idx, GFP_ATOMIC);
889 if (error == -EEXIST) {
890 struct page *filepage = find_get_page(inode->i_mapping, idx);
893 * There might be a more uptodate page coming down
894 * from a stacked writepage: forget our swappage if so.
896 if (PageUptodate(filepage))
898 page_cache_release(filepage);
902 delete_from_swap_cache(page);
903 set_page_dirty(page);
904 info->flags |= SHMEM_PAGEIN;
905 shmem_swp_set(info, ptr + offset, 0);
907 shmem_swp_unmap(ptr);
908 spin_unlock(&info->lock);
910 * Decrement swap count even when the entry is left behind:
911 * try_to_unuse will skip over mms, then reincrement count.
918 * shmem_unuse() search for an eventually swapped out shmem page.
920 int shmem_unuse(swp_entry_t entry, struct page *page)
922 struct list_head *p, *next;
923 struct shmem_inode_info *info;
926 spin_lock(&shmem_swaplist_lock);
927 list_for_each_safe(p, next, &shmem_swaplist) {
928 info = list_entry(p, struct shmem_inode_info, swaplist);
930 list_del_init(&info->swaplist);
931 else if (shmem_unuse_inode(info, entry, page)) {
932 /* move head to start search for next from here */
933 list_move_tail(&shmem_swaplist, &info->swaplist);
938 spin_unlock(&shmem_swaplist_lock);
943 * Move the page from the page cache to the swap cache.
945 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
947 struct shmem_inode_info *info;
948 swp_entry_t *entry, swap;
949 struct address_space *mapping;
953 BUG_ON(!PageLocked(page));
954 mapping = page->mapping;
956 inode = mapping->host;
957 info = SHMEM_I(inode);
958 if (info->flags & VM_LOCKED)
960 if (!total_swap_pages)
964 * shmem_backing_dev_info's capabilities prevent regular writeback or
965 * sync from ever calling shmem_writepage; but a stacking filesystem
966 * may use the ->writepage of its underlying filesystem, in which case
967 * tmpfs should write out to swap only in response to memory pressure,
968 * and not for pdflush or sync. However, in those cases, we do still
969 * want to check if there's a redundant swappage to be discarded.
971 if (wbc->for_reclaim)
972 swap = get_swap_page();
976 spin_lock(&info->lock);
977 if (index >= info->next_index) {
978 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
981 entry = shmem_swp_entry(info, index, NULL);
984 * The more uptodate page coming down from a stacked
985 * writepage should replace our old swappage.
987 free_swap_and_cache(*entry);
988 shmem_swp_set(info, entry, 0);
990 shmem_recalc_inode(inode);
992 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
993 remove_from_page_cache(page);
994 shmem_swp_set(info, entry, swap.val);
995 shmem_swp_unmap(entry);
996 spin_unlock(&info->lock);
997 if (list_empty(&info->swaplist)) {
998 spin_lock(&shmem_swaplist_lock);
999 /* move instead of add in case we're racing */
1000 list_move_tail(&info->swaplist, &shmem_swaplist);
1001 spin_unlock(&shmem_swaplist_lock);
1003 swap_duplicate(swap);
1004 BUG_ON(page_mapped(page));
1005 page_cache_release(page); /* pagecache ref */
1006 set_page_dirty(page);
1011 shmem_swp_unmap(entry);
1013 spin_unlock(&info->lock);
1016 set_page_dirty(page);
1017 if (wbc->for_reclaim)
1018 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1024 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
1026 char *nodelist = strchr(value, ':');
1030 /* NUL-terminate policy string */
1032 if (nodelist_parse(nodelist, *policy_nodes))
1034 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY]))
1037 if (!strcmp(value, "default")) {
1038 *policy = MPOL_DEFAULT;
1039 /* Don't allow a nodelist */
1042 } else if (!strcmp(value, "prefer")) {
1043 *policy = MPOL_PREFERRED;
1044 /* Insist on a nodelist of one node only */
1046 char *rest = nodelist;
1047 while (isdigit(*rest))
1052 } else if (!strcmp(value, "bind")) {
1053 *policy = MPOL_BIND;
1054 /* Insist on a nodelist */
1057 } else if (!strcmp(value, "interleave")) {
1058 *policy = MPOL_INTERLEAVE;
1060 * Default to online nodes with memory if no nodelist
1063 *policy_nodes = node_states[N_HIGH_MEMORY];
1067 /* Restore string for error message */
1073 static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1074 struct shmem_inode_info *info, unsigned long idx)
1076 struct vm_area_struct pvma;
1079 /* Create a pseudo vma that just contains the policy */
1081 pvma.vm_pgoff = idx;
1083 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1084 page = swapin_readahead(entry, gfp, &pvma, 0);
1085 mpol_free(pvma.vm_policy);
1089 static struct page *shmem_alloc_page(gfp_t gfp,
1090 struct shmem_inode_info *info, unsigned long idx)
1092 struct vm_area_struct pvma;
1095 /* Create a pseudo vma that just contains the policy */
1097 pvma.vm_pgoff = idx;
1099 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1100 page = alloc_page_vma(gfp, &pvma, 0);
1101 mpol_free(pvma.vm_policy);
1105 static inline int shmem_parse_mpol(char *value, int *policy,
1106 nodemask_t *policy_nodes)
1111 static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1112 struct shmem_inode_info *info, unsigned long idx)
1114 return swapin_readahead(entry, gfp, NULL, 0);
1117 static inline struct page *shmem_alloc_page(gfp_t gfp,
1118 struct shmem_inode_info *info, unsigned long idx)
1120 return alloc_page(gfp);
1125 * shmem_getpage - either get the page from swap or allocate a new one
1127 * If we allocate a new one we do not mark it dirty. That's up to the
1128 * vm. If we swap it in we mark it dirty since we also free the swap
1129 * entry since a page cannot live in both the swap and page cache
1131 static int shmem_getpage(struct inode *inode, unsigned long idx,
1132 struct page **pagep, enum sgp_type sgp, int *type)
1134 struct address_space *mapping = inode->i_mapping;
1135 struct shmem_inode_info *info = SHMEM_I(inode);
1136 struct shmem_sb_info *sbinfo;
1137 struct page *filepage = *pagep;
1138 struct page *swappage;
1144 if (idx >= SHMEM_MAX_INDEX)
1151 * Normally, filepage is NULL on entry, and either found
1152 * uptodate immediately, or allocated and zeroed, or read
1153 * in under swappage, which is then assigned to filepage.
1154 * But shmem_readpage (required for splice) passes in a locked
1155 * filepage, which may be found not uptodate by other callers
1156 * too, and may need to be copied from the swappage read in.
1160 filepage = find_lock_page(mapping, idx);
1161 if (filepage && PageUptodate(filepage))
1164 gfp = mapping_gfp_mask(mapping);
1166 spin_lock(&info->lock);
1167 shmem_recalc_inode(inode);
1168 entry = shmem_swp_alloc(info, idx, sgp);
1169 if (IS_ERR(entry)) {
1170 spin_unlock(&info->lock);
1171 error = PTR_ERR(entry);
1177 /* Look it up and read it in.. */
1178 swappage = lookup_swap_cache(swap);
1180 shmem_swp_unmap(entry);
1181 /* here we actually do the io */
1182 if (type && !(*type & VM_FAULT_MAJOR)) {
1183 __count_vm_event(PGMAJFAULT);
1184 *type |= VM_FAULT_MAJOR;
1186 spin_unlock(&info->lock);
1187 swappage = shmem_swapin(swap, gfp, info, idx);
1189 spin_lock(&info->lock);
1190 entry = shmem_swp_alloc(info, idx, sgp);
1192 error = PTR_ERR(entry);
1194 if (entry->val == swap.val)
1196 shmem_swp_unmap(entry);
1198 spin_unlock(&info->lock);
1203 wait_on_page_locked(swappage);
1204 page_cache_release(swappage);
1208 /* We have to do this with page locked to prevent races */
1209 if (TestSetPageLocked(swappage)) {
1210 shmem_swp_unmap(entry);
1211 spin_unlock(&info->lock);
1212 wait_on_page_locked(swappage);
1213 page_cache_release(swappage);
1216 if (PageWriteback(swappage)) {
1217 shmem_swp_unmap(entry);
1218 spin_unlock(&info->lock);
1219 wait_on_page_writeback(swappage);
1220 unlock_page(swappage);
1221 page_cache_release(swappage);
1224 if (!PageUptodate(swappage)) {
1225 shmem_swp_unmap(entry);
1226 spin_unlock(&info->lock);
1227 unlock_page(swappage);
1228 page_cache_release(swappage);
1234 shmem_swp_set(info, entry, 0);
1235 shmem_swp_unmap(entry);
1236 delete_from_swap_cache(swappage);
1237 spin_unlock(&info->lock);
1238 copy_highpage(filepage, swappage);
1239 unlock_page(swappage);
1240 page_cache_release(swappage);
1241 flush_dcache_page(filepage);
1242 SetPageUptodate(filepage);
1243 set_page_dirty(filepage);
1245 } else if (!(error = add_to_page_cache(
1246 swappage, mapping, idx, GFP_ATOMIC))) {
1247 info->flags |= SHMEM_PAGEIN;
1248 shmem_swp_set(info, entry, 0);
1249 shmem_swp_unmap(entry);
1250 delete_from_swap_cache(swappage);
1251 spin_unlock(&info->lock);
1252 filepage = swappage;
1253 set_page_dirty(filepage);
1256 shmem_swp_unmap(entry);
1257 spin_unlock(&info->lock);
1258 unlock_page(swappage);
1259 page_cache_release(swappage);
1260 if (error == -ENOMEM) {
1261 /* let kswapd refresh zone for GFP_ATOMICs */
1262 congestion_wait(WRITE, HZ/50);
1266 } else if (sgp == SGP_READ && !filepage) {
1267 shmem_swp_unmap(entry);
1268 filepage = find_get_page(mapping, idx);
1270 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1271 spin_unlock(&info->lock);
1272 wait_on_page_locked(filepage);
1273 page_cache_release(filepage);
1277 spin_unlock(&info->lock);
1279 shmem_swp_unmap(entry);
1280 sbinfo = SHMEM_SB(inode->i_sb);
1281 if (sbinfo->max_blocks) {
1282 spin_lock(&sbinfo->stat_lock);
1283 if (sbinfo->free_blocks == 0 ||
1284 shmem_acct_block(info->flags)) {
1285 spin_unlock(&sbinfo->stat_lock);
1286 spin_unlock(&info->lock);
1290 sbinfo->free_blocks--;
1291 inode->i_blocks += BLOCKS_PER_PAGE;
1292 spin_unlock(&sbinfo->stat_lock);
1293 } else if (shmem_acct_block(info->flags)) {
1294 spin_unlock(&info->lock);
1300 spin_unlock(&info->lock);
1301 filepage = shmem_alloc_page(gfp, info, idx);
1303 shmem_unacct_blocks(info->flags, 1);
1304 shmem_free_blocks(inode, 1);
1309 spin_lock(&info->lock);
1310 entry = shmem_swp_alloc(info, idx, sgp);
1312 error = PTR_ERR(entry);
1315 shmem_swp_unmap(entry);
1317 if (error || swap.val || 0 != add_to_page_cache_lru(
1318 filepage, mapping, idx, GFP_ATOMIC)) {
1319 spin_unlock(&info->lock);
1320 page_cache_release(filepage);
1321 shmem_unacct_blocks(info->flags, 1);
1322 shmem_free_blocks(inode, 1);
1328 info->flags |= SHMEM_PAGEIN;
1332 spin_unlock(&info->lock);
1333 clear_highpage(filepage);
1334 flush_dcache_page(filepage);
1335 SetPageUptodate(filepage);
1342 if (*pagep != filepage) {
1343 unlock_page(filepage);
1344 page_cache_release(filepage);
1349 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1351 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1355 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1356 return VM_FAULT_SIGBUS;
1358 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1360 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1362 mark_page_accessed(vmf->page);
1363 return ret | VM_FAULT_LOCKED;
1367 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1369 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1370 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1373 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1376 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1379 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1380 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1384 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1386 struct inode *inode = file->f_path.dentry->d_inode;
1387 struct shmem_inode_info *info = SHMEM_I(inode);
1388 int retval = -ENOMEM;
1390 spin_lock(&info->lock);
1391 if (lock && !(info->flags & VM_LOCKED)) {
1392 if (!user_shm_lock(inode->i_size, user))
1394 info->flags |= VM_LOCKED;
1396 if (!lock && (info->flags & VM_LOCKED) && user) {
1397 user_shm_unlock(inode->i_size, user);
1398 info->flags &= ~VM_LOCKED;
1402 spin_unlock(&info->lock);
1406 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1408 file_accessed(file);
1409 vma->vm_ops = &shmem_vm_ops;
1410 vma->vm_flags |= VM_CAN_NONLINEAR;
1414 static struct inode *
1415 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1417 struct inode *inode;
1418 struct shmem_inode_info *info;
1419 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1421 if (shmem_reserve_inode(sb))
1424 inode = new_inode(sb);
1426 inode->i_mode = mode;
1427 inode->i_uid = current->fsuid;
1428 inode->i_gid = current->fsgid;
1429 inode->i_blocks = 0;
1430 inode->i_mapping->a_ops = &shmem_aops;
1431 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1432 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1433 inode->i_generation = get_seconds();
1434 info = SHMEM_I(inode);
1435 memset(info, 0, (char *)inode - (char *)info);
1436 spin_lock_init(&info->lock);
1437 INIT_LIST_HEAD(&info->swaplist);
1439 switch (mode & S_IFMT) {
1441 inode->i_op = &shmem_special_inode_operations;
1442 init_special_inode(inode, mode, dev);
1445 inode->i_op = &shmem_inode_operations;
1446 inode->i_fop = &shmem_file_operations;
1447 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1448 &sbinfo->policy_nodes);
1452 /* Some things misbehave if size == 0 on a directory */
1453 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1454 inode->i_op = &shmem_dir_inode_operations;
1455 inode->i_fop = &simple_dir_operations;
1459 * Must not load anything in the rbtree,
1460 * mpol_free_shared_policy will not be called.
1462 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1467 shmem_free_inode(sb);
1472 static const struct inode_operations shmem_symlink_inode_operations;
1473 static const struct inode_operations shmem_symlink_inline_operations;
1476 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1477 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1478 * below the loop driver, in the generic fashion that many filesystems support.
1480 static int shmem_readpage(struct file *file, struct page *page)
1482 struct inode *inode = page->mapping->host;
1483 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1489 shmem_write_begin(struct file *file, struct address_space *mapping,
1490 loff_t pos, unsigned len, unsigned flags,
1491 struct page **pagep, void **fsdata)
1493 struct inode *inode = mapping->host;
1494 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1496 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1500 shmem_write_end(struct file *file, struct address_space *mapping,
1501 loff_t pos, unsigned len, unsigned copied,
1502 struct page *page, void *fsdata)
1504 struct inode *inode = mapping->host;
1506 if (pos + copied > inode->i_size)
1507 i_size_write(inode, pos + copied);
1510 set_page_dirty(page);
1511 page_cache_release(page);
1516 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1518 struct inode *inode = filp->f_path.dentry->d_inode;
1519 struct address_space *mapping = inode->i_mapping;
1520 unsigned long index, offset;
1522 index = *ppos >> PAGE_CACHE_SHIFT;
1523 offset = *ppos & ~PAGE_CACHE_MASK;
1526 struct page *page = NULL;
1527 unsigned long end_index, nr, ret;
1528 loff_t i_size = i_size_read(inode);
1530 end_index = i_size >> PAGE_CACHE_SHIFT;
1531 if (index > end_index)
1533 if (index == end_index) {
1534 nr = i_size & ~PAGE_CACHE_MASK;
1539 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1541 if (desc->error == -EINVAL)
1549 * We must evaluate after, since reads (unlike writes)
1550 * are called without i_mutex protection against truncate
1552 nr = PAGE_CACHE_SIZE;
1553 i_size = i_size_read(inode);
1554 end_index = i_size >> PAGE_CACHE_SHIFT;
1555 if (index == end_index) {
1556 nr = i_size & ~PAGE_CACHE_MASK;
1559 page_cache_release(page);
1567 * If users can be writing to this page using arbitrary
1568 * virtual addresses, take care about potential aliasing
1569 * before reading the page on the kernel side.
1571 if (mapping_writably_mapped(mapping))
1572 flush_dcache_page(page);
1574 * Mark the page accessed if we read the beginning.
1577 mark_page_accessed(page);
1579 page = ZERO_PAGE(0);
1580 page_cache_get(page);
1584 * Ok, we have the page, and it's up-to-date, so
1585 * now we can copy it to user space...
1587 * The actor routine returns how many bytes were actually used..
1588 * NOTE! This may not be the same as how much of a user buffer
1589 * we filled up (we may be padding etc), so we can only update
1590 * "pos" here (the actor routine has to update the user buffer
1591 * pointers and the remaining count).
1593 ret = actor(desc, page, offset, nr);
1595 index += offset >> PAGE_CACHE_SHIFT;
1596 offset &= ~PAGE_CACHE_MASK;
1598 page_cache_release(page);
1599 if (ret != nr || !desc->count)
1605 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1606 file_accessed(filp);
1609 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1611 read_descriptor_t desc;
1613 if ((ssize_t) count < 0)
1615 if (!access_ok(VERIFY_WRITE, buf, count))
1625 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1627 return desc.written;
1631 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1633 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1635 buf->f_type = TMPFS_MAGIC;
1636 buf->f_bsize = PAGE_CACHE_SIZE;
1637 buf->f_namelen = NAME_MAX;
1638 spin_lock(&sbinfo->stat_lock);
1639 if (sbinfo->max_blocks) {
1640 buf->f_blocks = sbinfo->max_blocks;
1641 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1643 if (sbinfo->max_inodes) {
1644 buf->f_files = sbinfo->max_inodes;
1645 buf->f_ffree = sbinfo->free_inodes;
1647 /* else leave those fields 0 like simple_statfs */
1648 spin_unlock(&sbinfo->stat_lock);
1653 * File creation. Allocate an inode, and we're done..
1656 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1658 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1659 int error = -ENOSPC;
1662 error = security_inode_init_security(inode, dir, NULL, NULL,
1665 if (error != -EOPNOTSUPP) {
1670 error = shmem_acl_init(inode, dir);
1675 if (dir->i_mode & S_ISGID) {
1676 inode->i_gid = dir->i_gid;
1678 inode->i_mode |= S_ISGID;
1680 dir->i_size += BOGO_DIRENT_SIZE;
1681 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1682 d_instantiate(dentry, inode);
1683 dget(dentry); /* Extra count - pin the dentry in core */
1688 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1692 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1698 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1699 struct nameidata *nd)
1701 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1707 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1709 struct inode *inode = old_dentry->d_inode;
1713 * No ordinary (disk based) filesystem counts links as inodes;
1714 * but each new link needs a new dentry, pinning lowmem, and
1715 * tmpfs dentries cannot be pruned until they are unlinked.
1717 ret = shmem_reserve_inode(inode->i_sb);
1721 dir->i_size += BOGO_DIRENT_SIZE;
1722 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1724 atomic_inc(&inode->i_count); /* New dentry reference */
1725 dget(dentry); /* Extra pinning count for the created dentry */
1726 d_instantiate(dentry, inode);
1731 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1733 struct inode *inode = dentry->d_inode;
1735 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1736 shmem_free_inode(inode->i_sb);
1738 dir->i_size -= BOGO_DIRENT_SIZE;
1739 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1741 dput(dentry); /* Undo the count from "create" - this does all the work */
1745 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1747 if (!simple_empty(dentry))
1750 drop_nlink(dentry->d_inode);
1752 return shmem_unlink(dir, dentry);
1756 * The VFS layer already does all the dentry stuff for rename,
1757 * we just have to decrement the usage count for the target if
1758 * it exists so that the VFS layer correctly free's it when it
1761 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1763 struct inode *inode = old_dentry->d_inode;
1764 int they_are_dirs = S_ISDIR(inode->i_mode);
1766 if (!simple_empty(new_dentry))
1769 if (new_dentry->d_inode) {
1770 (void) shmem_unlink(new_dir, new_dentry);
1772 drop_nlink(old_dir);
1773 } else if (they_are_dirs) {
1774 drop_nlink(old_dir);
1778 old_dir->i_size -= BOGO_DIRENT_SIZE;
1779 new_dir->i_size += BOGO_DIRENT_SIZE;
1780 old_dir->i_ctime = old_dir->i_mtime =
1781 new_dir->i_ctime = new_dir->i_mtime =
1782 inode->i_ctime = CURRENT_TIME;
1786 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1790 struct inode *inode;
1791 struct page *page = NULL;
1793 struct shmem_inode_info *info;
1795 len = strlen(symname) + 1;
1796 if (len > PAGE_CACHE_SIZE)
1797 return -ENAMETOOLONG;
1799 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1803 error = security_inode_init_security(inode, dir, NULL, NULL,
1806 if (error != -EOPNOTSUPP) {
1813 info = SHMEM_I(inode);
1814 inode->i_size = len-1;
1815 if (len <= (char *)inode - (char *)info) {
1817 memcpy(info, symname, len);
1818 inode->i_op = &shmem_symlink_inline_operations;
1820 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1826 inode->i_op = &shmem_symlink_inode_operations;
1827 kaddr = kmap_atomic(page, KM_USER0);
1828 memcpy(kaddr, symname, len);
1829 kunmap_atomic(kaddr, KM_USER0);
1830 set_page_dirty(page);
1831 page_cache_release(page);
1833 if (dir->i_mode & S_ISGID)
1834 inode->i_gid = dir->i_gid;
1835 dir->i_size += BOGO_DIRENT_SIZE;
1836 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1837 d_instantiate(dentry, inode);
1842 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1844 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1848 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1850 struct page *page = NULL;
1851 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1852 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1858 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1860 if (!IS_ERR(nd_get_link(nd))) {
1861 struct page *page = cookie;
1863 mark_page_accessed(page);
1864 page_cache_release(page);
1868 static const struct inode_operations shmem_symlink_inline_operations = {
1869 .readlink = generic_readlink,
1870 .follow_link = shmem_follow_link_inline,
1873 static const struct inode_operations shmem_symlink_inode_operations = {
1874 .truncate = shmem_truncate,
1875 .readlink = generic_readlink,
1876 .follow_link = shmem_follow_link,
1877 .put_link = shmem_put_link,
1880 #ifdef CONFIG_TMPFS_POSIX_ACL
1882 * Superblocks without xattr inode operations will get security.* xattr
1883 * support from the VFS "for free". As soon as we have any other xattrs
1884 * like ACLs, we also need to implement the security.* handlers at
1885 * filesystem level, though.
1888 static size_t shmem_xattr_security_list(struct inode *inode, char *list,
1889 size_t list_len, const char *name,
1892 return security_inode_listsecurity(inode, list, list_len);
1895 static int shmem_xattr_security_get(struct inode *inode, const char *name,
1896 void *buffer, size_t size)
1898 if (strcmp(name, "") == 0)
1900 return security_inode_getsecurity(inode, name, buffer, size,
1904 static int shmem_xattr_security_set(struct inode *inode, const char *name,
1905 const void *value, size_t size, int flags)
1907 if (strcmp(name, "") == 0)
1909 return security_inode_setsecurity(inode, name, value, size, flags);
1912 static struct xattr_handler shmem_xattr_security_handler = {
1913 .prefix = XATTR_SECURITY_PREFIX,
1914 .list = shmem_xattr_security_list,
1915 .get = shmem_xattr_security_get,
1916 .set = shmem_xattr_security_set,
1919 static struct xattr_handler *shmem_xattr_handlers[] = {
1920 &shmem_xattr_acl_access_handler,
1921 &shmem_xattr_acl_default_handler,
1922 &shmem_xattr_security_handler,
1927 static struct dentry *shmem_get_parent(struct dentry *child)
1929 return ERR_PTR(-ESTALE);
1932 static int shmem_match(struct inode *ino, void *vfh)
1936 inum = (inum << 32) | fh[1];
1937 return ino->i_ino == inum && fh[0] == ino->i_generation;
1940 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
1941 struct fid *fid, int fh_len, int fh_type)
1943 struct inode *inode;
1944 struct dentry *dentry = NULL;
1945 u64 inum = fid->raw[2];
1946 inum = (inum << 32) | fid->raw[1];
1951 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
1952 shmem_match, fid->raw);
1954 dentry = d_find_alias(inode);
1961 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
1964 struct inode *inode = dentry->d_inode;
1969 if (hlist_unhashed(&inode->i_hash)) {
1970 /* Unfortunately insert_inode_hash is not idempotent,
1971 * so as we hash inodes here rather than at creation
1972 * time, we need a lock to ensure we only try
1975 static DEFINE_SPINLOCK(lock);
1977 if (hlist_unhashed(&inode->i_hash))
1978 __insert_inode_hash(inode,
1979 inode->i_ino + inode->i_generation);
1983 fh[0] = inode->i_generation;
1984 fh[1] = inode->i_ino;
1985 fh[2] = ((__u64)inode->i_ino) >> 32;
1991 static const struct export_operations shmem_export_ops = {
1992 .get_parent = shmem_get_parent,
1993 .encode_fh = shmem_encode_fh,
1994 .fh_to_dentry = shmem_fh_to_dentry,
1997 static int shmem_parse_options(char *options, int *mode, uid_t *uid,
1998 gid_t *gid, unsigned long *blocks, unsigned long *inodes,
1999 int *policy, nodemask_t *policy_nodes)
2001 char *this_char, *value, *rest;
2003 while (options != NULL) {
2004 this_char = options;
2007 * NUL-terminate this option: unfortunately,
2008 * mount options form a comma-separated list,
2009 * but mpol's nodelist may also contain commas.
2011 options = strchr(options, ',');
2012 if (options == NULL)
2015 if (!isdigit(*options)) {
2022 if ((value = strchr(this_char,'=')) != NULL) {
2026 "tmpfs: No value for mount option '%s'\n",
2031 if (!strcmp(this_char,"size")) {
2032 unsigned long long size;
2033 size = memparse(value,&rest);
2035 size <<= PAGE_SHIFT;
2036 size *= totalram_pages;
2042 *blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2043 } else if (!strcmp(this_char,"nr_blocks")) {
2044 *blocks = memparse(value,&rest);
2047 } else if (!strcmp(this_char,"nr_inodes")) {
2048 *inodes = memparse(value,&rest);
2051 } else if (!strcmp(this_char,"mode")) {
2054 *mode = simple_strtoul(value,&rest,8);
2057 } else if (!strcmp(this_char,"uid")) {
2060 *uid = simple_strtoul(value,&rest,0);
2063 } else if (!strcmp(this_char,"gid")) {
2066 *gid = simple_strtoul(value,&rest,0);
2069 } else if (!strcmp(this_char,"mpol")) {
2070 if (shmem_parse_mpol(value,policy,policy_nodes))
2073 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2081 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2087 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2089 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2090 unsigned long max_blocks = sbinfo->max_blocks;
2091 unsigned long max_inodes = sbinfo->max_inodes;
2092 int policy = sbinfo->policy;
2093 nodemask_t policy_nodes = sbinfo->policy_nodes;
2094 unsigned long blocks;
2095 unsigned long inodes;
2096 int error = -EINVAL;
2098 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
2099 &max_inodes, &policy, &policy_nodes))
2102 spin_lock(&sbinfo->stat_lock);
2103 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2104 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2105 if (max_blocks < blocks)
2107 if (max_inodes < inodes)
2110 * Those tests also disallow limited->unlimited while any are in
2111 * use, so i_blocks will always be zero when max_blocks is zero;
2112 * but we must separately disallow unlimited->limited, because
2113 * in that case we have no record of how much is already in use.
2115 if (max_blocks && !sbinfo->max_blocks)
2117 if (max_inodes && !sbinfo->max_inodes)
2121 sbinfo->max_blocks = max_blocks;
2122 sbinfo->free_blocks = max_blocks - blocks;
2123 sbinfo->max_inodes = max_inodes;
2124 sbinfo->free_inodes = max_inodes - inodes;
2125 sbinfo->policy = policy;
2126 sbinfo->policy_nodes = policy_nodes;
2128 spin_unlock(&sbinfo->stat_lock);
2133 static void shmem_put_super(struct super_block *sb)
2135 kfree(sb->s_fs_info);
2136 sb->s_fs_info = NULL;
2139 static int shmem_fill_super(struct super_block *sb,
2140 void *data, int silent)
2142 struct inode *inode;
2143 struct dentry *root;
2144 int mode = S_IRWXUGO | S_ISVTX;
2145 uid_t uid = current->fsuid;
2146 gid_t gid = current->fsgid;
2148 struct shmem_sb_info *sbinfo;
2149 unsigned long blocks = 0;
2150 unsigned long inodes = 0;
2151 int policy = MPOL_DEFAULT;
2152 nodemask_t policy_nodes = node_states[N_HIGH_MEMORY];
2156 * Per default we only allow half of the physical ram per
2157 * tmpfs instance, limiting inodes to one per page of lowmem;
2158 * but the internal instance is left unlimited.
2160 if (!(sb->s_flags & MS_NOUSER)) {
2161 blocks = totalram_pages / 2;
2162 inodes = totalram_pages - totalhigh_pages;
2163 if (inodes > blocks)
2165 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2166 &inodes, &policy, &policy_nodes))
2169 sb->s_export_op = &shmem_export_ops;
2171 sb->s_flags |= MS_NOUSER;
2174 /* Round up to L1_CACHE_BYTES to resist false sharing */
2175 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2176 L1_CACHE_BYTES), GFP_KERNEL);
2180 spin_lock_init(&sbinfo->stat_lock);
2181 sbinfo->max_blocks = blocks;
2182 sbinfo->free_blocks = blocks;
2183 sbinfo->max_inodes = inodes;
2184 sbinfo->free_inodes = inodes;
2185 sbinfo->policy = policy;
2186 sbinfo->policy_nodes = policy_nodes;
2188 sb->s_fs_info = sbinfo;
2189 sb->s_maxbytes = SHMEM_MAX_BYTES;
2190 sb->s_blocksize = PAGE_CACHE_SIZE;
2191 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2192 sb->s_magic = TMPFS_MAGIC;
2193 sb->s_op = &shmem_ops;
2194 sb->s_time_gran = 1;
2195 #ifdef CONFIG_TMPFS_POSIX_ACL
2196 sb->s_xattr = shmem_xattr_handlers;
2197 sb->s_flags |= MS_POSIXACL;
2200 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2205 root = d_alloc_root(inode);
2214 shmem_put_super(sb);
2218 static struct kmem_cache *shmem_inode_cachep;
2220 static struct inode *shmem_alloc_inode(struct super_block *sb)
2222 struct shmem_inode_info *p;
2223 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2226 return &p->vfs_inode;
2229 static void shmem_destroy_inode(struct inode *inode)
2231 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2232 /* only struct inode is valid if it's an inline symlink */
2233 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2235 shmem_acl_destroy_inode(inode);
2236 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2239 static void init_once(struct kmem_cache *cachep, void *foo)
2241 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2243 inode_init_once(&p->vfs_inode);
2244 #ifdef CONFIG_TMPFS_POSIX_ACL
2246 p->i_default_acl = NULL;
2250 static int init_inodecache(void)
2252 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2253 sizeof(struct shmem_inode_info),
2254 0, SLAB_PANIC, init_once);
2258 static void destroy_inodecache(void)
2260 kmem_cache_destroy(shmem_inode_cachep);
2263 static const struct address_space_operations shmem_aops = {
2264 .writepage = shmem_writepage,
2265 .set_page_dirty = __set_page_dirty_no_writeback,
2267 .readpage = shmem_readpage,
2268 .write_begin = shmem_write_begin,
2269 .write_end = shmem_write_end,
2271 .migratepage = migrate_page,
2274 static const struct file_operations shmem_file_operations = {
2277 .llseek = generic_file_llseek,
2278 .read = shmem_file_read,
2279 .write = do_sync_write,
2280 .aio_write = generic_file_aio_write,
2281 .fsync = simple_sync_file,
2282 .splice_read = generic_file_splice_read,
2283 .splice_write = generic_file_splice_write,
2287 static const struct inode_operations shmem_inode_operations = {
2288 .truncate = shmem_truncate,
2289 .setattr = shmem_notify_change,
2290 .truncate_range = shmem_truncate_range,
2291 #ifdef CONFIG_TMPFS_POSIX_ACL
2292 .setxattr = generic_setxattr,
2293 .getxattr = generic_getxattr,
2294 .listxattr = generic_listxattr,
2295 .removexattr = generic_removexattr,
2296 .permission = shmem_permission,
2301 static const struct inode_operations shmem_dir_inode_operations = {
2303 .create = shmem_create,
2304 .lookup = simple_lookup,
2306 .unlink = shmem_unlink,
2307 .symlink = shmem_symlink,
2308 .mkdir = shmem_mkdir,
2309 .rmdir = shmem_rmdir,
2310 .mknod = shmem_mknod,
2311 .rename = shmem_rename,
2313 #ifdef CONFIG_TMPFS_POSIX_ACL
2314 .setattr = shmem_notify_change,
2315 .setxattr = generic_setxattr,
2316 .getxattr = generic_getxattr,
2317 .listxattr = generic_listxattr,
2318 .removexattr = generic_removexattr,
2319 .permission = shmem_permission,
2323 static const struct inode_operations shmem_special_inode_operations = {
2324 #ifdef CONFIG_TMPFS_POSIX_ACL
2325 .setattr = shmem_notify_change,
2326 .setxattr = generic_setxattr,
2327 .getxattr = generic_getxattr,
2328 .listxattr = generic_listxattr,
2329 .removexattr = generic_removexattr,
2330 .permission = shmem_permission,
2334 static const struct super_operations shmem_ops = {
2335 .alloc_inode = shmem_alloc_inode,
2336 .destroy_inode = shmem_destroy_inode,
2338 .statfs = shmem_statfs,
2339 .remount_fs = shmem_remount_fs,
2341 .delete_inode = shmem_delete_inode,
2342 .drop_inode = generic_delete_inode,
2343 .put_super = shmem_put_super,
2346 static struct vm_operations_struct shmem_vm_ops = {
2347 .fault = shmem_fault,
2349 .set_policy = shmem_set_policy,
2350 .get_policy = shmem_get_policy,
2355 static int shmem_get_sb(struct file_system_type *fs_type,
2356 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
2358 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
2361 static struct file_system_type tmpfs_fs_type = {
2362 .owner = THIS_MODULE,
2364 .get_sb = shmem_get_sb,
2365 .kill_sb = kill_litter_super,
2367 static struct vfsmount *shm_mnt;
2369 static int __init init_tmpfs(void)
2373 error = bdi_init(&shmem_backing_dev_info);
2377 error = init_inodecache();
2381 error = register_filesystem(&tmpfs_fs_type);
2383 printk(KERN_ERR "Could not register tmpfs\n");
2387 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2388 tmpfs_fs_type.name, NULL);
2389 if (IS_ERR(shm_mnt)) {
2390 error = PTR_ERR(shm_mnt);
2391 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2397 unregister_filesystem(&tmpfs_fs_type);
2399 destroy_inodecache();
2401 bdi_destroy(&shmem_backing_dev_info);
2403 shm_mnt = ERR_PTR(error);
2406 module_init(init_tmpfs)
2409 * shmem_file_setup - get an unlinked file living in tmpfs
2411 * @name: name for dentry (to be seen in /proc/<pid>/maps
2412 * @size: size to be set for the file
2415 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2419 struct inode *inode;
2420 struct dentry *dentry, *root;
2423 if (IS_ERR(shm_mnt))
2424 return (void *)shm_mnt;
2426 if (size < 0 || size > SHMEM_MAX_BYTES)
2427 return ERR_PTR(-EINVAL);
2429 if (shmem_acct_size(flags, size))
2430 return ERR_PTR(-ENOMEM);
2434 this.len = strlen(name);
2435 this.hash = 0; /* will go */
2436 root = shm_mnt->mnt_root;
2437 dentry = d_alloc(root, &this);
2442 file = get_empty_filp();
2447 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2451 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2452 d_instantiate(dentry, inode);
2453 inode->i_size = size;
2454 inode->i_nlink = 0; /* It is unlinked */
2455 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
2456 &shmem_file_operations);
2464 shmem_unacct_size(flags, size);
2465 return ERR_PTR(error);
2469 * shmem_zero_setup - setup a shared anonymous mapping
2471 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2473 int shmem_zero_setup(struct vm_area_struct *vma)
2476 loff_t size = vma->vm_end - vma->vm_start;
2478 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2480 return PTR_ERR(file);
2484 vma->vm_file = file;
2485 vma->vm_ops = &shmem_vm_ops;