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>
52 #include <linux/seq_file.h>
54 #include <asm/uaccess.h>
55 #include <asm/div64.h>
56 #include <asm/pgtable.h>
58 /* This magic number is used in glibc for posix shared memory */
59 #define TMPFS_MAGIC 0x01021994
61 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
62 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
63 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
65 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
66 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
68 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
70 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
71 #define SHMEM_PAGEIN VM_READ
72 #define SHMEM_TRUNCATE VM_WRITE
74 /* Definition to limit shmem_truncate's steps between cond_rescheds */
75 #define LATENCY_LIMIT 64
77 /* Pretend that each entry is of this size in directory's i_size */
78 #define BOGO_DIRENT_SIZE 20
80 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
82 SGP_READ, /* don't exceed i_size, don't allocate page */
83 SGP_CACHE, /* don't exceed i_size, may allocate page */
84 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
85 SGP_WRITE, /* may exceed i_size, may allocate page */
88 static unsigned long shmem_default_max_blocks(void)
90 return totalram_pages / 2;
93 static unsigned long shmem_default_max_inodes(void)
95 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
98 static int shmem_getpage(struct inode *inode, unsigned long idx,
99 struct page **pagep, enum sgp_type sgp, int *type);
101 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
104 * The above definition of ENTRIES_PER_PAGE, and the use of
105 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
106 * might be reconsidered if it ever diverges from PAGE_SIZE.
108 * Mobility flags are masked out as swap vectors cannot move
110 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
111 PAGE_CACHE_SHIFT-PAGE_SHIFT);
114 static inline void shmem_dir_free(struct page *page)
116 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
119 static struct page **shmem_dir_map(struct page *page)
121 return (struct page **)kmap_atomic(page, KM_USER0);
124 static inline void shmem_dir_unmap(struct page **dir)
126 kunmap_atomic(dir, KM_USER0);
129 static swp_entry_t *shmem_swp_map(struct page *page)
131 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
134 static inline void shmem_swp_balance_unmap(void)
137 * When passing a pointer to an i_direct entry, to code which
138 * also handles indirect entries and so will shmem_swp_unmap,
139 * we must arrange for the preempt count to remain in balance.
140 * What kmap_atomic of a lowmem page does depends on config
141 * and architecture, so pretend to kmap_atomic some lowmem page.
143 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
146 static inline void shmem_swp_unmap(swp_entry_t *entry)
148 kunmap_atomic(entry, KM_USER1);
151 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
153 return sb->s_fs_info;
157 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
158 * for shared memory and for shared anonymous (/dev/zero) mappings
159 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
160 * consistent with the pre-accounting of private mappings ...
162 static inline int shmem_acct_size(unsigned long flags, loff_t size)
164 return (flags & VM_ACCOUNT)?
165 security_vm_enough_memory(VM_ACCT(size)): 0;
168 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
170 if (flags & VM_ACCOUNT)
171 vm_unacct_memory(VM_ACCT(size));
175 * ... whereas tmpfs objects are accounted incrementally as
176 * pages are allocated, in order to allow huge sparse files.
177 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
178 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
180 static inline int shmem_acct_block(unsigned long flags)
182 return (flags & VM_ACCOUNT)?
183 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
186 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
188 if (!(flags & VM_ACCOUNT))
189 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
192 static const struct super_operations shmem_ops;
193 static const struct address_space_operations shmem_aops;
194 static const struct file_operations shmem_file_operations;
195 static const struct inode_operations shmem_inode_operations;
196 static const struct inode_operations shmem_dir_inode_operations;
197 static const struct inode_operations shmem_special_inode_operations;
198 static struct vm_operations_struct shmem_vm_ops;
200 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
201 .ra_pages = 0, /* No readahead */
202 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
203 .unplug_io_fn = default_unplug_io_fn,
206 static LIST_HEAD(shmem_swaplist);
207 static DEFINE_MUTEX(shmem_swaplist_mutex);
209 static void shmem_free_blocks(struct inode *inode, long pages)
211 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
212 if (sbinfo->max_blocks) {
213 spin_lock(&sbinfo->stat_lock);
214 sbinfo->free_blocks += pages;
215 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
216 spin_unlock(&sbinfo->stat_lock);
220 static int shmem_reserve_inode(struct super_block *sb)
222 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
223 if (sbinfo->max_inodes) {
224 spin_lock(&sbinfo->stat_lock);
225 if (!sbinfo->free_inodes) {
226 spin_unlock(&sbinfo->stat_lock);
229 sbinfo->free_inodes--;
230 spin_unlock(&sbinfo->stat_lock);
235 static void shmem_free_inode(struct super_block *sb)
237 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
238 if (sbinfo->max_inodes) {
239 spin_lock(&sbinfo->stat_lock);
240 sbinfo->free_inodes++;
241 spin_unlock(&sbinfo->stat_lock);
246 * shmem_recalc_inode - recalculate the size of an inode
248 * @inode: inode to recalc
250 * We have to calculate the free blocks since the mm can drop
251 * undirtied hole pages behind our back.
253 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
254 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
256 * It has to be called with the spinlock held.
258 static void shmem_recalc_inode(struct inode *inode)
260 struct shmem_inode_info *info = SHMEM_I(inode);
263 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
265 info->alloced -= freed;
266 shmem_unacct_blocks(info->flags, freed);
267 shmem_free_blocks(inode, freed);
272 * shmem_swp_entry - find the swap vector position in the info structure
274 * @info: info structure for the inode
275 * @index: index of the page to find
276 * @page: optional page to add to the structure. Has to be preset to
279 * If there is no space allocated yet it will return NULL when
280 * page is NULL, else it will use the page for the needed block,
281 * setting it to NULL on return to indicate that it has been used.
283 * The swap vector is organized the following way:
285 * There are SHMEM_NR_DIRECT entries directly stored in the
286 * shmem_inode_info structure. So small files do not need an addional
289 * For pages with index > SHMEM_NR_DIRECT there is the pointer
290 * i_indirect which points to a page which holds in the first half
291 * doubly indirect blocks, in the second half triple indirect blocks:
293 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
294 * following layout (for SHMEM_NR_DIRECT == 16):
296 * i_indirect -> dir --> 16-19
309 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
311 unsigned long offset;
315 if (index < SHMEM_NR_DIRECT) {
316 shmem_swp_balance_unmap();
317 return info->i_direct+index;
319 if (!info->i_indirect) {
321 info->i_indirect = *page;
324 return NULL; /* need another page */
327 index -= SHMEM_NR_DIRECT;
328 offset = index % ENTRIES_PER_PAGE;
329 index /= ENTRIES_PER_PAGE;
330 dir = shmem_dir_map(info->i_indirect);
332 if (index >= ENTRIES_PER_PAGE/2) {
333 index -= ENTRIES_PER_PAGE/2;
334 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
335 index %= ENTRIES_PER_PAGE;
342 shmem_dir_unmap(dir);
343 return NULL; /* need another page */
345 shmem_dir_unmap(dir);
346 dir = shmem_dir_map(subdir);
352 if (!page || !(subdir = *page)) {
353 shmem_dir_unmap(dir);
354 return NULL; /* need a page */
359 shmem_dir_unmap(dir);
360 return shmem_swp_map(subdir) + offset;
363 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
365 long incdec = value? 1: -1;
368 info->swapped += incdec;
369 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
370 struct page *page = kmap_atomic_to_page(entry);
371 set_page_private(page, page_private(page) + incdec);
376 * shmem_swp_alloc - get the position of the swap entry for the page.
377 * If it does not exist allocate the entry.
379 * @info: info structure for the inode
380 * @index: index of the page to find
381 * @sgp: check and recheck i_size? skip allocation?
383 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
385 struct inode *inode = &info->vfs_inode;
386 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
387 struct page *page = NULL;
390 if (sgp != SGP_WRITE &&
391 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
392 return ERR_PTR(-EINVAL);
394 while (!(entry = shmem_swp_entry(info, index, &page))) {
396 return shmem_swp_map(ZERO_PAGE(0));
398 * Test free_blocks against 1 not 0, since we have 1 data
399 * page (and perhaps indirect index pages) yet to allocate:
400 * a waste to allocate index if we cannot allocate data.
402 if (sbinfo->max_blocks) {
403 spin_lock(&sbinfo->stat_lock);
404 if (sbinfo->free_blocks <= 1) {
405 spin_unlock(&sbinfo->stat_lock);
406 return ERR_PTR(-ENOSPC);
408 sbinfo->free_blocks--;
409 inode->i_blocks += BLOCKS_PER_PAGE;
410 spin_unlock(&sbinfo->stat_lock);
413 spin_unlock(&info->lock);
414 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
416 set_page_private(page, 0);
417 spin_lock(&info->lock);
420 shmem_free_blocks(inode, 1);
421 return ERR_PTR(-ENOMEM);
423 if (sgp != SGP_WRITE &&
424 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
425 entry = ERR_PTR(-EINVAL);
428 if (info->next_index <= index)
429 info->next_index = index + 1;
432 /* another task gave its page, or truncated the file */
433 shmem_free_blocks(inode, 1);
434 shmem_dir_free(page);
436 if (info->next_index <= index && !IS_ERR(entry))
437 info->next_index = index + 1;
442 * shmem_free_swp - free some swap entries in a directory
444 * @dir: pointer to the directory
445 * @edir: pointer after last entry of the directory
446 * @punch_lock: pointer to spinlock when needed for the holepunch case
448 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
449 spinlock_t *punch_lock)
451 spinlock_t *punch_unlock = NULL;
455 for (ptr = dir; ptr < edir; ptr++) {
457 if (unlikely(punch_lock)) {
458 punch_unlock = punch_lock;
460 spin_lock(punch_unlock);
464 free_swap_and_cache(*ptr);
465 *ptr = (swp_entry_t){0};
470 spin_unlock(punch_unlock);
474 static int shmem_map_and_free_swp(struct page *subdir, int offset,
475 int limit, struct page ***dir, spinlock_t *punch_lock)
480 ptr = shmem_swp_map(subdir);
481 for (; offset < limit; offset += LATENCY_LIMIT) {
482 int size = limit - offset;
483 if (size > LATENCY_LIMIT)
484 size = LATENCY_LIMIT;
485 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
487 if (need_resched()) {
488 shmem_swp_unmap(ptr);
490 shmem_dir_unmap(*dir);
494 ptr = shmem_swp_map(subdir);
497 shmem_swp_unmap(ptr);
501 static void shmem_free_pages(struct list_head *next)
507 page = container_of(next, struct page, lru);
509 shmem_dir_free(page);
511 if (freed >= LATENCY_LIMIT) {
518 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
520 struct shmem_inode_info *info = SHMEM_I(inode);
525 unsigned long diroff;
531 LIST_HEAD(pages_to_free);
532 long nr_pages_to_free = 0;
533 long nr_swaps_freed = 0;
537 spinlock_t *needs_lock;
538 spinlock_t *punch_lock;
539 unsigned long upper_limit;
541 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
542 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
543 if (idx >= info->next_index)
546 spin_lock(&info->lock);
547 info->flags |= SHMEM_TRUNCATE;
548 if (likely(end == (loff_t) -1)) {
549 limit = info->next_index;
550 upper_limit = SHMEM_MAX_INDEX;
551 info->next_index = idx;
555 if (end + 1 >= inode->i_size) { /* we may free a little more */
556 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
558 upper_limit = SHMEM_MAX_INDEX;
560 limit = (end + 1) >> PAGE_CACHE_SHIFT;
563 needs_lock = &info->lock;
567 topdir = info->i_indirect;
568 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
569 info->i_indirect = NULL;
571 list_add(&topdir->lru, &pages_to_free);
573 spin_unlock(&info->lock);
575 if (info->swapped && idx < SHMEM_NR_DIRECT) {
576 ptr = info->i_direct;
578 if (size > SHMEM_NR_DIRECT)
579 size = SHMEM_NR_DIRECT;
580 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
584 * If there are no indirect blocks or we are punching a hole
585 * below indirect blocks, nothing to be done.
587 if (!topdir || limit <= SHMEM_NR_DIRECT)
591 * The truncation case has already dropped info->lock, and we're safe
592 * because i_size and next_index have already been lowered, preventing
593 * access beyond. But in the punch_hole case, we still need to take
594 * the lock when updating the swap directory, because there might be
595 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
596 * shmem_writepage. However, whenever we find we can remove a whole
597 * directory page (not at the misaligned start or end of the range),
598 * we first NULLify its pointer in the level above, and then have no
599 * need to take the lock when updating its contents: needs_lock and
600 * punch_lock (either pointing to info->lock or NULL) manage this.
603 upper_limit -= SHMEM_NR_DIRECT;
604 limit -= SHMEM_NR_DIRECT;
605 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
606 offset = idx % ENTRIES_PER_PAGE;
609 dir = shmem_dir_map(topdir);
610 stage = ENTRIES_PER_PAGEPAGE/2;
611 if (idx < ENTRIES_PER_PAGEPAGE/2) {
613 diroff = idx/ENTRIES_PER_PAGE;
615 dir += ENTRIES_PER_PAGE/2;
616 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
618 stage += ENTRIES_PER_PAGEPAGE;
621 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
622 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
623 if (!diroff && !offset && upper_limit >= stage) {
625 spin_lock(needs_lock);
627 spin_unlock(needs_lock);
632 list_add(&middir->lru, &pages_to_free);
634 shmem_dir_unmap(dir);
635 dir = shmem_dir_map(middir);
643 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
644 if (unlikely(idx == stage)) {
645 shmem_dir_unmap(dir);
646 dir = shmem_dir_map(topdir) +
647 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
650 idx += ENTRIES_PER_PAGEPAGE;
654 stage = idx + ENTRIES_PER_PAGEPAGE;
657 needs_lock = &info->lock;
658 if (upper_limit >= stage) {
660 spin_lock(needs_lock);
662 spin_unlock(needs_lock);
667 list_add(&middir->lru, &pages_to_free);
669 shmem_dir_unmap(dir);
671 dir = shmem_dir_map(middir);
674 punch_lock = needs_lock;
675 subdir = dir[diroff];
676 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
678 spin_lock(needs_lock);
680 spin_unlock(needs_lock);
685 list_add(&subdir->lru, &pages_to_free);
687 if (subdir && page_private(subdir) /* has swap entries */) {
689 if (size > ENTRIES_PER_PAGE)
690 size = ENTRIES_PER_PAGE;
691 freed = shmem_map_and_free_swp(subdir,
692 offset, size, &dir, punch_lock);
694 dir = shmem_dir_map(middir);
695 nr_swaps_freed += freed;
696 if (offset || punch_lock) {
697 spin_lock(&info->lock);
698 set_page_private(subdir,
699 page_private(subdir) - freed);
700 spin_unlock(&info->lock);
702 BUG_ON(page_private(subdir) != freed);
707 shmem_dir_unmap(dir);
709 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
711 * Call truncate_inode_pages again: racing shmem_unuse_inode
712 * may have swizzled a page in from swap since vmtruncate or
713 * generic_delete_inode did it, before we lowered next_index.
714 * Also, though shmem_getpage checks i_size before adding to
715 * cache, no recheck after: so fix the narrow window there too.
717 * Recalling truncate_inode_pages_range and unmap_mapping_range
718 * every time for punch_hole (which never got a chance to clear
719 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
720 * yet hardly ever necessary: try to optimize them out later.
722 truncate_inode_pages_range(inode->i_mapping, start, end);
724 unmap_mapping_range(inode->i_mapping, start,
728 spin_lock(&info->lock);
729 info->flags &= ~SHMEM_TRUNCATE;
730 info->swapped -= nr_swaps_freed;
731 if (nr_pages_to_free)
732 shmem_free_blocks(inode, nr_pages_to_free);
733 shmem_recalc_inode(inode);
734 spin_unlock(&info->lock);
737 * Empty swap vector directory pages to be freed?
739 if (!list_empty(&pages_to_free)) {
740 pages_to_free.prev->next = NULL;
741 shmem_free_pages(pages_to_free.next);
745 static void shmem_truncate(struct inode *inode)
747 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
750 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
752 struct inode *inode = dentry->d_inode;
753 struct page *page = NULL;
756 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
757 if (attr->ia_size < inode->i_size) {
759 * If truncating down to a partial page, then
760 * if that page is already allocated, hold it
761 * in memory until the truncation is over, so
762 * truncate_partial_page cannnot miss it were
763 * it assigned to swap.
765 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
766 (void) shmem_getpage(inode,
767 attr->ia_size>>PAGE_CACHE_SHIFT,
768 &page, SGP_READ, NULL);
773 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
774 * detect if any pages might have been added to cache
775 * after truncate_inode_pages. But we needn't bother
776 * if it's being fully truncated to zero-length: the
777 * nrpages check is efficient enough in that case.
780 struct shmem_inode_info *info = SHMEM_I(inode);
781 spin_lock(&info->lock);
782 info->flags &= ~SHMEM_PAGEIN;
783 spin_unlock(&info->lock);
788 error = inode_change_ok(inode, attr);
790 error = inode_setattr(inode, attr);
791 #ifdef CONFIG_TMPFS_POSIX_ACL
792 if (!error && (attr->ia_valid & ATTR_MODE))
793 error = generic_acl_chmod(inode, &shmem_acl_ops);
796 page_cache_release(page);
800 static void shmem_delete_inode(struct inode *inode)
802 struct shmem_inode_info *info = SHMEM_I(inode);
804 if (inode->i_op->truncate == shmem_truncate) {
805 truncate_inode_pages(inode->i_mapping, 0);
806 shmem_unacct_size(info->flags, inode->i_size);
808 shmem_truncate(inode);
809 if (!list_empty(&info->swaplist)) {
810 mutex_lock(&shmem_swaplist_mutex);
811 list_del_init(&info->swaplist);
812 mutex_unlock(&shmem_swaplist_mutex);
815 BUG_ON(inode->i_blocks);
816 shmem_free_inode(inode->i_sb);
820 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
824 for (ptr = dir; ptr < edir; ptr++) {
825 if (ptr->val == entry.val)
831 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
845 ptr = info->i_direct;
846 spin_lock(&info->lock);
847 if (!info->swapped) {
848 list_del_init(&info->swaplist);
851 limit = info->next_index;
853 if (size > SHMEM_NR_DIRECT)
854 size = SHMEM_NR_DIRECT;
855 offset = shmem_find_swp(entry, ptr, ptr+size);
858 if (!info->i_indirect)
861 dir = shmem_dir_map(info->i_indirect);
862 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
864 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
865 if (unlikely(idx == stage)) {
866 shmem_dir_unmap(dir-1);
867 if (cond_resched_lock(&info->lock)) {
868 /* check it has not been truncated */
869 if (limit > info->next_index) {
870 limit = info->next_index;
875 dir = shmem_dir_map(info->i_indirect) +
876 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
879 idx += ENTRIES_PER_PAGEPAGE;
883 stage = idx + ENTRIES_PER_PAGEPAGE;
885 shmem_dir_unmap(dir);
886 dir = shmem_dir_map(subdir);
889 if (subdir && page_private(subdir)) {
890 ptr = shmem_swp_map(subdir);
892 if (size > ENTRIES_PER_PAGE)
893 size = ENTRIES_PER_PAGE;
894 offset = shmem_find_swp(entry, ptr, ptr+size);
895 shmem_swp_unmap(ptr);
897 shmem_dir_unmap(dir);
903 shmem_dir_unmap(dir-1);
905 spin_unlock(&info->lock);
909 inode = igrab(&info->vfs_inode);
910 spin_unlock(&info->lock);
913 * Move _head_ to start search for next from here.
914 * But be careful: shmem_delete_inode checks list_empty without taking
915 * mutex, and there's an instant in list_move_tail when info->swaplist
916 * would appear empty, if it were the only one on shmem_swaplist. We
917 * could avoid doing it if inode NULL; or use this minor optimization.
919 if (shmem_swaplist.next != &info->swaplist)
920 list_move_tail(&shmem_swaplist, &info->swaplist);
921 mutex_unlock(&shmem_swaplist_mutex);
926 /* Precharge page while we can wait, compensate afterwards */
927 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
930 error = radix_tree_preload(GFP_KERNEL);
935 spin_lock(&info->lock);
936 ptr = shmem_swp_entry(info, idx, NULL);
937 if (ptr && ptr->val == entry.val)
938 error = add_to_page_cache(page, inode->i_mapping,
940 if (error == -EEXIST) {
941 struct page *filepage = find_get_page(inode->i_mapping, idx);
945 * There might be a more uptodate page coming down
946 * from a stacked writepage: forget our swappage if so.
948 if (PageUptodate(filepage))
950 page_cache_release(filepage);
954 delete_from_swap_cache(page);
955 set_page_dirty(page);
956 info->flags |= SHMEM_PAGEIN;
957 shmem_swp_set(info, ptr, 0);
959 error = 1; /* not an error, but entry was found */
962 shmem_swp_unmap(ptr);
963 spin_unlock(&info->lock);
964 radix_tree_preload_end();
966 mem_cgroup_uncharge_page(page);
969 page_cache_release(page);
970 iput(inode); /* allows for NULL */
975 * shmem_unuse() search for an eventually swapped out shmem page.
977 int shmem_unuse(swp_entry_t entry, struct page *page)
979 struct list_head *p, *next;
980 struct shmem_inode_info *info;
983 mutex_lock(&shmem_swaplist_mutex);
984 list_for_each_safe(p, next, &shmem_swaplist) {
985 info = list_entry(p, struct shmem_inode_info, swaplist);
986 found = shmem_unuse_inode(info, entry, page);
991 mutex_unlock(&shmem_swaplist_mutex);
992 out: return found; /* 0 or 1 or -ENOMEM */
996 * Move the page from the page cache to the swap cache.
998 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1000 struct shmem_inode_info *info;
1001 swp_entry_t *entry, swap;
1002 struct address_space *mapping;
1003 unsigned long index;
1004 struct inode *inode;
1006 BUG_ON(!PageLocked(page));
1007 mapping = page->mapping;
1008 index = page->index;
1009 inode = mapping->host;
1010 info = SHMEM_I(inode);
1011 if (info->flags & VM_LOCKED)
1013 if (!total_swap_pages)
1017 * shmem_backing_dev_info's capabilities prevent regular writeback or
1018 * sync from ever calling shmem_writepage; but a stacking filesystem
1019 * may use the ->writepage of its underlying filesystem, in which case
1020 * tmpfs should write out to swap only in response to memory pressure,
1021 * and not for pdflush or sync. However, in those cases, we do still
1022 * want to check if there's a redundant swappage to be discarded.
1024 if (wbc->for_reclaim)
1025 swap = get_swap_page();
1029 spin_lock(&info->lock);
1030 if (index >= info->next_index) {
1031 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1034 entry = shmem_swp_entry(info, index, NULL);
1037 * The more uptodate page coming down from a stacked
1038 * writepage should replace our old swappage.
1040 free_swap_and_cache(*entry);
1041 shmem_swp_set(info, entry, 0);
1043 shmem_recalc_inode(inode);
1045 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1046 remove_from_page_cache(page);
1047 shmem_swp_set(info, entry, swap.val);
1048 shmem_swp_unmap(entry);
1049 if (list_empty(&info->swaplist))
1050 inode = igrab(inode);
1053 spin_unlock(&info->lock);
1054 swap_duplicate(swap);
1055 BUG_ON(page_mapped(page));
1056 page_cache_release(page); /* pagecache ref */
1057 set_page_dirty(page);
1060 mutex_lock(&shmem_swaplist_mutex);
1061 /* move instead of add in case we're racing */
1062 list_move_tail(&info->swaplist, &shmem_swaplist);
1063 mutex_unlock(&shmem_swaplist_mutex);
1069 shmem_swp_unmap(entry);
1071 spin_unlock(&info->lock);
1074 set_page_dirty(page);
1075 if (wbc->for_reclaim)
1076 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1083 static int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
1085 char *nodelist = strchr(value, ':');
1089 /* NUL-terminate policy string */
1091 if (nodelist_parse(nodelist, *policy_nodes))
1093 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY]))
1096 if (!strcmp(value, "default")) {
1097 *policy = MPOL_DEFAULT;
1098 /* Don't allow a nodelist */
1101 } else if (!strcmp(value, "prefer")) {
1102 *policy = MPOL_PREFERRED;
1103 /* Insist on a nodelist of one node only */
1105 char *rest = nodelist;
1106 while (isdigit(*rest))
1111 } else if (!strcmp(value, "bind")) {
1112 *policy = MPOL_BIND;
1113 /* Insist on a nodelist */
1116 } else if (!strcmp(value, "interleave")) {
1117 *policy = MPOL_INTERLEAVE;
1119 * Default to online nodes with memory if no nodelist
1122 *policy_nodes = node_states[N_HIGH_MEMORY];
1126 /* Restore string for error message */
1132 static void shmem_show_mpol(struct seq_file *seq, int policy,
1133 const nodemask_t policy_nodes)
1135 char *policy_string;
1138 case MPOL_PREFERRED:
1139 policy_string = "prefer";
1142 policy_string = "bind";
1144 case MPOL_INTERLEAVE:
1145 policy_string = "interleave";
1152 seq_printf(seq, ",mpol=%s", policy_string);
1154 if (policy != MPOL_INTERLEAVE ||
1155 !nodes_equal(policy_nodes, node_states[N_HIGH_MEMORY])) {
1159 len = nodelist_scnprintf(buffer, sizeof(buffer), policy_nodes);
1160 if (len < sizeof(buffer))
1161 seq_printf(seq, ":%s", buffer);
1163 seq_printf(seq, ":?");
1166 #endif /* CONFIG_TMPFS */
1168 static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1169 struct shmem_inode_info *info, unsigned long idx)
1171 struct vm_area_struct pvma;
1174 /* Create a pseudo vma that just contains the policy */
1176 pvma.vm_pgoff = idx;
1178 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1179 page = swapin_readahead(entry, gfp, &pvma, 0);
1180 mpol_free(pvma.vm_policy);
1184 static struct page *shmem_alloc_page(gfp_t gfp,
1185 struct shmem_inode_info *info, unsigned long idx)
1187 struct vm_area_struct pvma;
1190 /* Create a pseudo vma that just contains the policy */
1192 pvma.vm_pgoff = idx;
1194 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1195 page = alloc_page_vma(gfp, &pvma, 0);
1196 mpol_free(pvma.vm_policy);
1199 #else /* !CONFIG_NUMA */
1201 static inline int shmem_parse_mpol(char *value, int *policy,
1202 nodemask_t *policy_nodes)
1207 static inline void shmem_show_mpol(struct seq_file *seq, int policy,
1208 const nodemask_t policy_nodes)
1211 #endif /* CONFIG_TMPFS */
1213 static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1214 struct shmem_inode_info *info, unsigned long idx)
1216 return swapin_readahead(entry, gfp, NULL, 0);
1219 static inline struct page *shmem_alloc_page(gfp_t gfp,
1220 struct shmem_inode_info *info, unsigned long idx)
1222 return alloc_page(gfp);
1224 #endif /* CONFIG_NUMA */
1227 * shmem_getpage - either get the page from swap or allocate a new one
1229 * If we allocate a new one we do not mark it dirty. That's up to the
1230 * vm. If we swap it in we mark it dirty since we also free the swap
1231 * entry since a page cannot live in both the swap and page cache
1233 static int shmem_getpage(struct inode *inode, unsigned long idx,
1234 struct page **pagep, enum sgp_type sgp, int *type)
1236 struct address_space *mapping = inode->i_mapping;
1237 struct shmem_inode_info *info = SHMEM_I(inode);
1238 struct shmem_sb_info *sbinfo;
1239 struct page *filepage = *pagep;
1240 struct page *swappage;
1246 if (idx >= SHMEM_MAX_INDEX)
1253 * Normally, filepage is NULL on entry, and either found
1254 * uptodate immediately, or allocated and zeroed, or read
1255 * in under swappage, which is then assigned to filepage.
1256 * But shmem_readpage (required for splice) passes in a locked
1257 * filepage, which may be found not uptodate by other callers
1258 * too, and may need to be copied from the swappage read in.
1262 filepage = find_lock_page(mapping, idx);
1263 if (filepage && PageUptodate(filepage))
1266 gfp = mapping_gfp_mask(mapping);
1269 * Try to preload while we can wait, to not make a habit of
1270 * draining atomic reserves; but don't latch on to this cpu.
1272 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1275 radix_tree_preload_end();
1278 spin_lock(&info->lock);
1279 shmem_recalc_inode(inode);
1280 entry = shmem_swp_alloc(info, idx, sgp);
1281 if (IS_ERR(entry)) {
1282 spin_unlock(&info->lock);
1283 error = PTR_ERR(entry);
1289 /* Look it up and read it in.. */
1290 swappage = lookup_swap_cache(swap);
1292 shmem_swp_unmap(entry);
1293 /* here we actually do the io */
1294 if (type && !(*type & VM_FAULT_MAJOR)) {
1295 __count_vm_event(PGMAJFAULT);
1296 *type |= VM_FAULT_MAJOR;
1298 spin_unlock(&info->lock);
1299 swappage = shmem_swapin(swap, gfp, info, idx);
1301 spin_lock(&info->lock);
1302 entry = shmem_swp_alloc(info, idx, sgp);
1304 error = PTR_ERR(entry);
1306 if (entry->val == swap.val)
1308 shmem_swp_unmap(entry);
1310 spin_unlock(&info->lock);
1315 wait_on_page_locked(swappage);
1316 page_cache_release(swappage);
1320 /* We have to do this with page locked to prevent races */
1321 if (TestSetPageLocked(swappage)) {
1322 shmem_swp_unmap(entry);
1323 spin_unlock(&info->lock);
1324 wait_on_page_locked(swappage);
1325 page_cache_release(swappage);
1328 if (PageWriteback(swappage)) {
1329 shmem_swp_unmap(entry);
1330 spin_unlock(&info->lock);
1331 wait_on_page_writeback(swappage);
1332 unlock_page(swappage);
1333 page_cache_release(swappage);
1336 if (!PageUptodate(swappage)) {
1337 shmem_swp_unmap(entry);
1338 spin_unlock(&info->lock);
1339 unlock_page(swappage);
1340 page_cache_release(swappage);
1346 shmem_swp_set(info, entry, 0);
1347 shmem_swp_unmap(entry);
1348 delete_from_swap_cache(swappage);
1349 spin_unlock(&info->lock);
1350 copy_highpage(filepage, swappage);
1351 unlock_page(swappage);
1352 page_cache_release(swappage);
1353 flush_dcache_page(filepage);
1354 SetPageUptodate(filepage);
1355 set_page_dirty(filepage);
1357 } else if (!(error = add_to_page_cache(
1358 swappage, mapping, idx, GFP_NOWAIT))) {
1359 info->flags |= SHMEM_PAGEIN;
1360 shmem_swp_set(info, entry, 0);
1361 shmem_swp_unmap(entry);
1362 delete_from_swap_cache(swappage);
1363 spin_unlock(&info->lock);
1364 filepage = swappage;
1365 set_page_dirty(filepage);
1368 shmem_swp_unmap(entry);
1369 spin_unlock(&info->lock);
1370 unlock_page(swappage);
1371 page_cache_release(swappage);
1372 if (error == -ENOMEM) {
1373 /* allow reclaim from this memory cgroup */
1374 error = mem_cgroup_cache_charge(NULL,
1375 current->mm, gfp & ~__GFP_HIGHMEM);
1381 } else if (sgp == SGP_READ && !filepage) {
1382 shmem_swp_unmap(entry);
1383 filepage = find_get_page(mapping, idx);
1385 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1386 spin_unlock(&info->lock);
1387 wait_on_page_locked(filepage);
1388 page_cache_release(filepage);
1392 spin_unlock(&info->lock);
1394 shmem_swp_unmap(entry);
1395 sbinfo = SHMEM_SB(inode->i_sb);
1396 if (sbinfo->max_blocks) {
1397 spin_lock(&sbinfo->stat_lock);
1398 if (sbinfo->free_blocks == 0 ||
1399 shmem_acct_block(info->flags)) {
1400 spin_unlock(&sbinfo->stat_lock);
1401 spin_unlock(&info->lock);
1405 sbinfo->free_blocks--;
1406 inode->i_blocks += BLOCKS_PER_PAGE;
1407 spin_unlock(&sbinfo->stat_lock);
1408 } else if (shmem_acct_block(info->flags)) {
1409 spin_unlock(&info->lock);
1415 spin_unlock(&info->lock);
1416 filepage = shmem_alloc_page(gfp, info, idx);
1418 shmem_unacct_blocks(info->flags, 1);
1419 shmem_free_blocks(inode, 1);
1424 /* Precharge page while we can wait, compensate after */
1425 error = mem_cgroup_cache_charge(filepage, current->mm,
1426 gfp & ~__GFP_HIGHMEM);
1428 page_cache_release(filepage);
1429 shmem_unacct_blocks(info->flags, 1);
1430 shmem_free_blocks(inode, 1);
1435 spin_lock(&info->lock);
1436 entry = shmem_swp_alloc(info, idx, sgp);
1438 error = PTR_ERR(entry);
1441 shmem_swp_unmap(entry);
1443 if (error || swap.val || 0 != add_to_page_cache_lru(
1444 filepage, mapping, idx, GFP_NOWAIT)) {
1445 spin_unlock(&info->lock);
1446 mem_cgroup_uncharge_page(filepage);
1447 page_cache_release(filepage);
1448 shmem_unacct_blocks(info->flags, 1);
1449 shmem_free_blocks(inode, 1);
1455 mem_cgroup_uncharge_page(filepage);
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 mark_page_accessed(vmf->page);
1493 return ret | VM_FAULT_LOCKED;
1497 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1499 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1500 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1503 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1506 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1509 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1510 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1514 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1516 struct inode *inode = file->f_path.dentry->d_inode;
1517 struct shmem_inode_info *info = SHMEM_I(inode);
1518 int retval = -ENOMEM;
1520 spin_lock(&info->lock);
1521 if (lock && !(info->flags & VM_LOCKED)) {
1522 if (!user_shm_lock(inode->i_size, user))
1524 info->flags |= VM_LOCKED;
1526 if (!lock && (info->flags & VM_LOCKED) && user) {
1527 user_shm_unlock(inode->i_size, user);
1528 info->flags &= ~VM_LOCKED;
1532 spin_unlock(&info->lock);
1536 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1538 file_accessed(file);
1539 vma->vm_ops = &shmem_vm_ops;
1540 vma->vm_flags |= VM_CAN_NONLINEAR;
1544 static struct inode *
1545 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1547 struct inode *inode;
1548 struct shmem_inode_info *info;
1549 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1551 if (shmem_reserve_inode(sb))
1554 inode = new_inode(sb);
1556 inode->i_mode = mode;
1557 inode->i_uid = current->fsuid;
1558 inode->i_gid = current->fsgid;
1559 inode->i_blocks = 0;
1560 inode->i_mapping->a_ops = &shmem_aops;
1561 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1562 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1563 inode->i_generation = get_seconds();
1564 info = SHMEM_I(inode);
1565 memset(info, 0, (char *)inode - (char *)info);
1566 spin_lock_init(&info->lock);
1567 INIT_LIST_HEAD(&info->swaplist);
1569 switch (mode & S_IFMT) {
1571 inode->i_op = &shmem_special_inode_operations;
1572 init_special_inode(inode, mode, dev);
1575 inode->i_op = &shmem_inode_operations;
1576 inode->i_fop = &shmem_file_operations;
1577 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1578 &sbinfo->policy_nodes);
1582 /* Some things misbehave if size == 0 on a directory */
1583 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1584 inode->i_op = &shmem_dir_inode_operations;
1585 inode->i_fop = &simple_dir_operations;
1589 * Must not load anything in the rbtree,
1590 * mpol_free_shared_policy will not be called.
1592 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1597 shmem_free_inode(sb);
1602 static const struct inode_operations shmem_symlink_inode_operations;
1603 static const struct inode_operations shmem_symlink_inline_operations;
1606 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1607 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1608 * below the loop driver, in the generic fashion that many filesystems support.
1610 static int shmem_readpage(struct file *file, struct page *page)
1612 struct inode *inode = page->mapping->host;
1613 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1619 shmem_write_begin(struct file *file, struct address_space *mapping,
1620 loff_t pos, unsigned len, unsigned flags,
1621 struct page **pagep, void **fsdata)
1623 struct inode *inode = mapping->host;
1624 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1626 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1630 shmem_write_end(struct file *file, struct address_space *mapping,
1631 loff_t pos, unsigned len, unsigned copied,
1632 struct page *page, void *fsdata)
1634 struct inode *inode = mapping->host;
1636 if (pos + copied > inode->i_size)
1637 i_size_write(inode, pos + copied);
1640 set_page_dirty(page);
1641 page_cache_release(page);
1646 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1648 struct inode *inode = filp->f_path.dentry->d_inode;
1649 struct address_space *mapping = inode->i_mapping;
1650 unsigned long index, offset;
1651 enum sgp_type sgp = SGP_READ;
1654 * Might this read be for a stacking filesystem? Then when reading
1655 * holes of a sparse file, we actually need to allocate those pages,
1656 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1658 if (segment_eq(get_fs(), KERNEL_DS))
1661 index = *ppos >> PAGE_CACHE_SHIFT;
1662 offset = *ppos & ~PAGE_CACHE_MASK;
1665 struct page *page = NULL;
1666 unsigned long end_index, nr, ret;
1667 loff_t i_size = i_size_read(inode);
1669 end_index = i_size >> PAGE_CACHE_SHIFT;
1670 if (index > end_index)
1672 if (index == end_index) {
1673 nr = i_size & ~PAGE_CACHE_MASK;
1678 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1680 if (desc->error == -EINVAL)
1688 * We must evaluate after, since reads (unlike writes)
1689 * are called without i_mutex protection against truncate
1691 nr = PAGE_CACHE_SIZE;
1692 i_size = i_size_read(inode);
1693 end_index = i_size >> PAGE_CACHE_SHIFT;
1694 if (index == end_index) {
1695 nr = i_size & ~PAGE_CACHE_MASK;
1698 page_cache_release(page);
1706 * If users can be writing to this page using arbitrary
1707 * virtual addresses, take care about potential aliasing
1708 * before reading the page on the kernel side.
1710 if (mapping_writably_mapped(mapping))
1711 flush_dcache_page(page);
1713 * Mark the page accessed if we read the beginning.
1716 mark_page_accessed(page);
1718 page = ZERO_PAGE(0);
1719 page_cache_get(page);
1723 * Ok, we have the page, and it's up-to-date, so
1724 * now we can copy it to user space...
1726 * The actor routine returns how many bytes were actually used..
1727 * NOTE! This may not be the same as how much of a user buffer
1728 * we filled up (we may be padding etc), so we can only update
1729 * "pos" here (the actor routine has to update the user buffer
1730 * pointers and the remaining count).
1732 ret = actor(desc, page, offset, nr);
1734 index += offset >> PAGE_CACHE_SHIFT;
1735 offset &= ~PAGE_CACHE_MASK;
1737 page_cache_release(page);
1738 if (ret != nr || !desc->count)
1744 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1745 file_accessed(filp);
1748 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1750 read_descriptor_t desc;
1752 if ((ssize_t) count < 0)
1754 if (!access_ok(VERIFY_WRITE, buf, count))
1764 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1766 return desc.written;
1770 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1772 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1774 buf->f_type = TMPFS_MAGIC;
1775 buf->f_bsize = PAGE_CACHE_SIZE;
1776 buf->f_namelen = NAME_MAX;
1777 spin_lock(&sbinfo->stat_lock);
1778 if (sbinfo->max_blocks) {
1779 buf->f_blocks = sbinfo->max_blocks;
1780 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1782 if (sbinfo->max_inodes) {
1783 buf->f_files = sbinfo->max_inodes;
1784 buf->f_ffree = sbinfo->free_inodes;
1786 /* else leave those fields 0 like simple_statfs */
1787 spin_unlock(&sbinfo->stat_lock);
1792 * File creation. Allocate an inode, and we're done..
1795 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1797 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1798 int error = -ENOSPC;
1801 error = security_inode_init_security(inode, dir, NULL, NULL,
1804 if (error != -EOPNOTSUPP) {
1809 error = shmem_acl_init(inode, dir);
1814 if (dir->i_mode & S_ISGID) {
1815 inode->i_gid = dir->i_gid;
1817 inode->i_mode |= S_ISGID;
1819 dir->i_size += BOGO_DIRENT_SIZE;
1820 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1821 d_instantiate(dentry, inode);
1822 dget(dentry); /* Extra count - pin the dentry in core */
1827 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1831 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1837 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1838 struct nameidata *nd)
1840 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1846 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1848 struct inode *inode = old_dentry->d_inode;
1852 * No ordinary (disk based) filesystem counts links as inodes;
1853 * but each new link needs a new dentry, pinning lowmem, and
1854 * tmpfs dentries cannot be pruned until they are unlinked.
1856 ret = shmem_reserve_inode(inode->i_sb);
1860 dir->i_size += BOGO_DIRENT_SIZE;
1861 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1863 atomic_inc(&inode->i_count); /* New dentry reference */
1864 dget(dentry); /* Extra pinning count for the created dentry */
1865 d_instantiate(dentry, inode);
1870 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1872 struct inode *inode = dentry->d_inode;
1874 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1875 shmem_free_inode(inode->i_sb);
1877 dir->i_size -= BOGO_DIRENT_SIZE;
1878 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1880 dput(dentry); /* Undo the count from "create" - this does all the work */
1884 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1886 if (!simple_empty(dentry))
1889 drop_nlink(dentry->d_inode);
1891 return shmem_unlink(dir, dentry);
1895 * The VFS layer already does all the dentry stuff for rename,
1896 * we just have to decrement the usage count for the target if
1897 * it exists so that the VFS layer correctly free's it when it
1900 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1902 struct inode *inode = old_dentry->d_inode;
1903 int they_are_dirs = S_ISDIR(inode->i_mode);
1905 if (!simple_empty(new_dentry))
1908 if (new_dentry->d_inode) {
1909 (void) shmem_unlink(new_dir, new_dentry);
1911 drop_nlink(old_dir);
1912 } else if (they_are_dirs) {
1913 drop_nlink(old_dir);
1917 old_dir->i_size -= BOGO_DIRENT_SIZE;
1918 new_dir->i_size += BOGO_DIRENT_SIZE;
1919 old_dir->i_ctime = old_dir->i_mtime =
1920 new_dir->i_ctime = new_dir->i_mtime =
1921 inode->i_ctime = CURRENT_TIME;
1925 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1929 struct inode *inode;
1930 struct page *page = NULL;
1932 struct shmem_inode_info *info;
1934 len = strlen(symname) + 1;
1935 if (len > PAGE_CACHE_SIZE)
1936 return -ENAMETOOLONG;
1938 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1942 error = security_inode_init_security(inode, dir, NULL, NULL,
1945 if (error != -EOPNOTSUPP) {
1952 info = SHMEM_I(inode);
1953 inode->i_size = len-1;
1954 if (len <= (char *)inode - (char *)info) {
1956 memcpy(info, symname, len);
1957 inode->i_op = &shmem_symlink_inline_operations;
1959 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1965 inode->i_op = &shmem_symlink_inode_operations;
1966 kaddr = kmap_atomic(page, KM_USER0);
1967 memcpy(kaddr, symname, len);
1968 kunmap_atomic(kaddr, KM_USER0);
1969 set_page_dirty(page);
1970 page_cache_release(page);
1972 if (dir->i_mode & S_ISGID)
1973 inode->i_gid = dir->i_gid;
1974 dir->i_size += BOGO_DIRENT_SIZE;
1975 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1976 d_instantiate(dentry, inode);
1981 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1983 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1987 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1989 struct page *page = NULL;
1990 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1991 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1997 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1999 if (!IS_ERR(nd_get_link(nd))) {
2000 struct page *page = cookie;
2002 mark_page_accessed(page);
2003 page_cache_release(page);
2007 static const struct inode_operations shmem_symlink_inline_operations = {
2008 .readlink = generic_readlink,
2009 .follow_link = shmem_follow_link_inline,
2012 static const struct inode_operations shmem_symlink_inode_operations = {
2013 .truncate = shmem_truncate,
2014 .readlink = generic_readlink,
2015 .follow_link = shmem_follow_link,
2016 .put_link = shmem_put_link,
2019 #ifdef CONFIG_TMPFS_POSIX_ACL
2021 * Superblocks without xattr inode operations will get security.* xattr
2022 * support from the VFS "for free". As soon as we have any other xattrs
2023 * like ACLs, we also need to implement the security.* handlers at
2024 * filesystem level, though.
2027 static size_t shmem_xattr_security_list(struct inode *inode, char *list,
2028 size_t list_len, const char *name,
2031 return security_inode_listsecurity(inode, list, list_len);
2034 static int shmem_xattr_security_get(struct inode *inode, const char *name,
2035 void *buffer, size_t size)
2037 if (strcmp(name, "") == 0)
2039 return xattr_getsecurity(inode, name, buffer, size);
2042 static int shmem_xattr_security_set(struct inode *inode, const char *name,
2043 const void *value, size_t size, int flags)
2045 if (strcmp(name, "") == 0)
2047 return security_inode_setsecurity(inode, name, value, size, flags);
2050 static struct xattr_handler shmem_xattr_security_handler = {
2051 .prefix = XATTR_SECURITY_PREFIX,
2052 .list = shmem_xattr_security_list,
2053 .get = shmem_xattr_security_get,
2054 .set = shmem_xattr_security_set,
2057 static struct xattr_handler *shmem_xattr_handlers[] = {
2058 &shmem_xattr_acl_access_handler,
2059 &shmem_xattr_acl_default_handler,
2060 &shmem_xattr_security_handler,
2065 static struct dentry *shmem_get_parent(struct dentry *child)
2067 return ERR_PTR(-ESTALE);
2070 static int shmem_match(struct inode *ino, void *vfh)
2074 inum = (inum << 32) | fh[1];
2075 return ino->i_ino == inum && fh[0] == ino->i_generation;
2078 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2079 struct fid *fid, int fh_len, int fh_type)
2081 struct inode *inode;
2082 struct dentry *dentry = NULL;
2083 u64 inum = fid->raw[2];
2084 inum = (inum << 32) | fid->raw[1];
2089 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2090 shmem_match, fid->raw);
2092 dentry = d_find_alias(inode);
2099 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2102 struct inode *inode = dentry->d_inode;
2107 if (hlist_unhashed(&inode->i_hash)) {
2108 /* Unfortunately insert_inode_hash is not idempotent,
2109 * so as we hash inodes here rather than at creation
2110 * time, we need a lock to ensure we only try
2113 static DEFINE_SPINLOCK(lock);
2115 if (hlist_unhashed(&inode->i_hash))
2116 __insert_inode_hash(inode,
2117 inode->i_ino + inode->i_generation);
2121 fh[0] = inode->i_generation;
2122 fh[1] = inode->i_ino;
2123 fh[2] = ((__u64)inode->i_ino) >> 32;
2129 static const struct export_operations shmem_export_ops = {
2130 .get_parent = shmem_get_parent,
2131 .encode_fh = shmem_encode_fh,
2132 .fh_to_dentry = shmem_fh_to_dentry,
2135 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2138 char *this_char, *value, *rest;
2140 while (options != NULL) {
2141 this_char = options;
2144 * NUL-terminate this option: unfortunately,
2145 * mount options form a comma-separated list,
2146 * but mpol's nodelist may also contain commas.
2148 options = strchr(options, ',');
2149 if (options == NULL)
2152 if (!isdigit(*options)) {
2159 if ((value = strchr(this_char,'=')) != NULL) {
2163 "tmpfs: No value for mount option '%s'\n",
2168 if (!strcmp(this_char,"size")) {
2169 unsigned long long size;
2170 size = memparse(value,&rest);
2172 size <<= PAGE_SHIFT;
2173 size *= totalram_pages;
2179 sbinfo->max_blocks =
2180 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2181 } else if (!strcmp(this_char,"nr_blocks")) {
2182 sbinfo->max_blocks = memparse(value, &rest);
2185 } else if (!strcmp(this_char,"nr_inodes")) {
2186 sbinfo->max_inodes = memparse(value, &rest);
2189 } else if (!strcmp(this_char,"mode")) {
2192 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2195 } else if (!strcmp(this_char,"uid")) {
2198 sbinfo->uid = simple_strtoul(value, &rest, 0);
2201 } else if (!strcmp(this_char,"gid")) {
2204 sbinfo->gid = simple_strtoul(value, &rest, 0);
2207 } else if (!strcmp(this_char,"mpol")) {
2208 if (shmem_parse_mpol(value, &sbinfo->policy,
2209 &sbinfo->policy_nodes))
2212 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2220 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2226 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2228 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2229 struct shmem_sb_info config = *sbinfo;
2230 unsigned long blocks;
2231 unsigned long inodes;
2232 int error = -EINVAL;
2234 if (shmem_parse_options(data, &config, true))
2237 spin_lock(&sbinfo->stat_lock);
2238 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2239 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2240 if (config.max_blocks < blocks)
2242 if (config.max_inodes < inodes)
2245 * Those tests also disallow limited->unlimited while any are in
2246 * use, so i_blocks will always be zero when max_blocks is zero;
2247 * but we must separately disallow unlimited->limited, because
2248 * in that case we have no record of how much is already in use.
2250 if (config.max_blocks && !sbinfo->max_blocks)
2252 if (config.max_inodes && !sbinfo->max_inodes)
2256 sbinfo->max_blocks = config.max_blocks;
2257 sbinfo->free_blocks = config.max_blocks - blocks;
2258 sbinfo->max_inodes = config.max_inodes;
2259 sbinfo->free_inodes = config.max_inodes - inodes;
2260 sbinfo->policy = config.policy;
2261 sbinfo->policy_nodes = config.policy_nodes;
2263 spin_unlock(&sbinfo->stat_lock);
2267 static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2269 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2271 if (sbinfo->max_blocks != shmem_default_max_blocks())
2272 seq_printf(seq, ",size=%luk",
2273 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2274 if (sbinfo->max_inodes != shmem_default_max_inodes())
2275 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2276 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2277 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2278 if (sbinfo->uid != 0)
2279 seq_printf(seq, ",uid=%u", sbinfo->uid);
2280 if (sbinfo->gid != 0)
2281 seq_printf(seq, ",gid=%u", sbinfo->gid);
2282 shmem_show_mpol(seq, sbinfo->policy, sbinfo->policy_nodes);
2285 #endif /* CONFIG_TMPFS */
2287 static void shmem_put_super(struct super_block *sb)
2289 kfree(sb->s_fs_info);
2290 sb->s_fs_info = NULL;
2293 static int shmem_fill_super(struct super_block *sb,
2294 void *data, int silent)
2296 struct inode *inode;
2297 struct dentry *root;
2298 struct shmem_sb_info *sbinfo;
2301 /* Round up to L1_CACHE_BYTES to resist false sharing */
2302 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2303 L1_CACHE_BYTES), GFP_KERNEL);
2307 sbinfo->max_blocks = 0;
2308 sbinfo->max_inodes = 0;
2309 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2310 sbinfo->uid = current->fsuid;
2311 sbinfo->gid = current->fsgid;
2312 sbinfo->policy = MPOL_DEFAULT;
2313 sbinfo->policy_nodes = node_states[N_HIGH_MEMORY];
2314 sb->s_fs_info = sbinfo;
2318 * Per default we only allow half of the physical ram per
2319 * tmpfs instance, limiting inodes to one per page of lowmem;
2320 * but the internal instance is left unlimited.
2322 if (!(sb->s_flags & MS_NOUSER)) {
2323 sbinfo->max_blocks = shmem_default_max_blocks();
2324 sbinfo->max_inodes = shmem_default_max_inodes();
2325 if (shmem_parse_options(data, sbinfo, false)) {
2330 sb->s_export_op = &shmem_export_ops;
2332 sb->s_flags |= MS_NOUSER;
2335 spin_lock_init(&sbinfo->stat_lock);
2336 sbinfo->free_blocks = sbinfo->max_blocks;
2337 sbinfo->free_inodes = sbinfo->max_inodes;
2339 sb->s_maxbytes = SHMEM_MAX_BYTES;
2340 sb->s_blocksize = PAGE_CACHE_SIZE;
2341 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2342 sb->s_magic = TMPFS_MAGIC;
2343 sb->s_op = &shmem_ops;
2344 sb->s_time_gran = 1;
2345 #ifdef CONFIG_TMPFS_POSIX_ACL
2346 sb->s_xattr = shmem_xattr_handlers;
2347 sb->s_flags |= MS_POSIXACL;
2350 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0);
2353 inode->i_uid = sbinfo->uid;
2354 inode->i_gid = sbinfo->gid;
2355 root = d_alloc_root(inode);
2364 shmem_put_super(sb);
2368 static struct kmem_cache *shmem_inode_cachep;
2370 static struct inode *shmem_alloc_inode(struct super_block *sb)
2372 struct shmem_inode_info *p;
2373 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2376 return &p->vfs_inode;
2379 static void shmem_destroy_inode(struct inode *inode)
2381 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2382 /* only struct inode is valid if it's an inline symlink */
2383 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2385 shmem_acl_destroy_inode(inode);
2386 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2389 static void init_once(struct kmem_cache *cachep, void *foo)
2391 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2393 inode_init_once(&p->vfs_inode);
2394 #ifdef CONFIG_TMPFS_POSIX_ACL
2396 p->i_default_acl = NULL;
2400 static int init_inodecache(void)
2402 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2403 sizeof(struct shmem_inode_info),
2404 0, SLAB_PANIC, init_once);
2408 static void destroy_inodecache(void)
2410 kmem_cache_destroy(shmem_inode_cachep);
2413 static const struct address_space_operations shmem_aops = {
2414 .writepage = shmem_writepage,
2415 .set_page_dirty = __set_page_dirty_no_writeback,
2417 .readpage = shmem_readpage,
2418 .write_begin = shmem_write_begin,
2419 .write_end = shmem_write_end,
2421 .migratepage = migrate_page,
2424 static const struct file_operations shmem_file_operations = {
2427 .llseek = generic_file_llseek,
2428 .read = shmem_file_read,
2429 .write = do_sync_write,
2430 .aio_write = generic_file_aio_write,
2431 .fsync = simple_sync_file,
2432 .splice_read = generic_file_splice_read,
2433 .splice_write = generic_file_splice_write,
2437 static const struct inode_operations shmem_inode_operations = {
2438 .truncate = shmem_truncate,
2439 .setattr = shmem_notify_change,
2440 .truncate_range = shmem_truncate_range,
2441 #ifdef CONFIG_TMPFS_POSIX_ACL
2442 .setxattr = generic_setxattr,
2443 .getxattr = generic_getxattr,
2444 .listxattr = generic_listxattr,
2445 .removexattr = generic_removexattr,
2446 .permission = shmem_permission,
2451 static const struct inode_operations shmem_dir_inode_operations = {
2453 .create = shmem_create,
2454 .lookup = simple_lookup,
2456 .unlink = shmem_unlink,
2457 .symlink = shmem_symlink,
2458 .mkdir = shmem_mkdir,
2459 .rmdir = shmem_rmdir,
2460 .mknod = shmem_mknod,
2461 .rename = shmem_rename,
2463 #ifdef CONFIG_TMPFS_POSIX_ACL
2464 .setattr = shmem_notify_change,
2465 .setxattr = generic_setxattr,
2466 .getxattr = generic_getxattr,
2467 .listxattr = generic_listxattr,
2468 .removexattr = generic_removexattr,
2469 .permission = shmem_permission,
2473 static const struct inode_operations shmem_special_inode_operations = {
2474 #ifdef CONFIG_TMPFS_POSIX_ACL
2475 .setattr = shmem_notify_change,
2476 .setxattr = generic_setxattr,
2477 .getxattr = generic_getxattr,
2478 .listxattr = generic_listxattr,
2479 .removexattr = generic_removexattr,
2480 .permission = shmem_permission,
2484 static const struct super_operations shmem_ops = {
2485 .alloc_inode = shmem_alloc_inode,
2486 .destroy_inode = shmem_destroy_inode,
2488 .statfs = shmem_statfs,
2489 .remount_fs = shmem_remount_fs,
2490 .show_options = shmem_show_options,
2492 .delete_inode = shmem_delete_inode,
2493 .drop_inode = generic_delete_inode,
2494 .put_super = shmem_put_super,
2497 static struct vm_operations_struct shmem_vm_ops = {
2498 .fault = shmem_fault,
2500 .set_policy = shmem_set_policy,
2501 .get_policy = shmem_get_policy,
2506 static int shmem_get_sb(struct file_system_type *fs_type,
2507 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
2509 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
2512 static struct file_system_type tmpfs_fs_type = {
2513 .owner = THIS_MODULE,
2515 .get_sb = shmem_get_sb,
2516 .kill_sb = kill_litter_super,
2518 static struct vfsmount *shm_mnt;
2520 static int __init init_tmpfs(void)
2524 error = bdi_init(&shmem_backing_dev_info);
2528 error = init_inodecache();
2532 error = register_filesystem(&tmpfs_fs_type);
2534 printk(KERN_ERR "Could not register tmpfs\n");
2538 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2539 tmpfs_fs_type.name, NULL);
2540 if (IS_ERR(shm_mnt)) {
2541 error = PTR_ERR(shm_mnt);
2542 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2548 unregister_filesystem(&tmpfs_fs_type);
2550 destroy_inodecache();
2552 bdi_destroy(&shmem_backing_dev_info);
2554 shm_mnt = ERR_PTR(error);
2557 module_init(init_tmpfs)
2560 * shmem_file_setup - get an unlinked file living in tmpfs
2562 * @name: name for dentry (to be seen in /proc/<pid>/maps
2563 * @size: size to be set for the file
2566 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2570 struct inode *inode;
2571 struct dentry *dentry, *root;
2574 if (IS_ERR(shm_mnt))
2575 return (void *)shm_mnt;
2577 if (size < 0 || size > SHMEM_MAX_BYTES)
2578 return ERR_PTR(-EINVAL);
2580 if (shmem_acct_size(flags, size))
2581 return ERR_PTR(-ENOMEM);
2585 this.len = strlen(name);
2586 this.hash = 0; /* will go */
2587 root = shm_mnt->mnt_root;
2588 dentry = d_alloc(root, &this);
2593 file = get_empty_filp();
2598 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2602 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2603 d_instantiate(dentry, inode);
2604 inode->i_size = size;
2605 inode->i_nlink = 0; /* It is unlinked */
2606 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
2607 &shmem_file_operations);
2615 shmem_unacct_size(flags, size);
2616 return ERR_PTR(error);
2620 * shmem_zero_setup - setup a shared anonymous mapping
2622 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2624 int shmem_zero_setup(struct vm_area_struct *vma)
2627 loff_t size = vma->vm_end - vma->vm_start;
2629 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2631 return PTR_ERR(file);
2635 vma->vm_file = file;
2636 vma->vm_ops = &shmem_vm_ops;