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/generic_acl.h>
32 #include <linux/mman.h>
33 #include <linux/file.h>
34 #include <linux/swap.h>
35 #include <linux/pagemap.h>
36 #include <linux/string.h>
37 #include <linux/slab.h>
38 #include <linux/backing-dev.h>
39 #include <linux/shmem_fs.h>
40 #include <linux/mount.h>
41 #include <linux/writeback.h>
42 #include <linux/vfs.h>
43 #include <linux/blkdev.h>
44 #include <linux/security.h>
45 #include <linux/swapops.h>
46 #include <linux/mempolicy.h>
47 #include <linux/namei.h>
48 #include <linux/ctype.h>
49 #include <linux/migrate.h>
50 #include <linux/highmem.h>
51 #include <linux/backing-dev.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_QUICK
, /* don't try more than file page cache lookup */
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_WRITE
, /* may exceed i_size, may allocate page */
87 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
88 struct page
**pagep
, enum sgp_type sgp
, int *type
);
90 static inline struct page
*shmem_dir_alloc(gfp_t gfp_mask
)
93 * The above definition of ENTRIES_PER_PAGE, and the use of
94 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
95 * might be reconsidered if it ever diverges from PAGE_SIZE.
97 * __GFP_MOVABLE is masked out as swap vectors cannot move
99 return alloc_pages((gfp_mask
& ~__GFP_MOVABLE
) | __GFP_ZERO
,
100 PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
103 static inline void shmem_dir_free(struct page
*page
)
105 __free_pages(page
, PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
108 static struct page
**shmem_dir_map(struct page
*page
)
110 return (struct page
**)kmap_atomic(page
, KM_USER0
);
113 static inline void shmem_dir_unmap(struct page
**dir
)
115 kunmap_atomic(dir
, KM_USER0
);
118 static swp_entry_t
*shmem_swp_map(struct page
*page
)
120 return (swp_entry_t
*)kmap_atomic(page
, KM_USER1
);
123 static inline void shmem_swp_balance_unmap(void)
126 * When passing a pointer to an i_direct entry, to code which
127 * also handles indirect entries and so will shmem_swp_unmap,
128 * we must arrange for the preempt count to remain in balance.
129 * What kmap_atomic of a lowmem page does depends on config
130 * and architecture, so pretend to kmap_atomic some lowmem page.
132 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1
);
135 static inline void shmem_swp_unmap(swp_entry_t
*entry
)
137 kunmap_atomic(entry
, KM_USER1
);
140 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
142 return sb
->s_fs_info
;
146 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
147 * for shared memory and for shared anonymous (/dev/zero) mappings
148 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
149 * consistent with the pre-accounting of private mappings ...
151 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
153 return (flags
& VM_ACCOUNT
)?
154 security_vm_enough_memory(VM_ACCT(size
)): 0;
157 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
159 if (flags
& VM_ACCOUNT
)
160 vm_unacct_memory(VM_ACCT(size
));
164 * ... whereas tmpfs objects are accounted incrementally as
165 * pages are allocated, in order to allow huge sparse files.
166 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
167 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
169 static inline int shmem_acct_block(unsigned long flags
)
171 return (flags
& VM_ACCOUNT
)?
172 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE
));
175 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
177 if (!(flags
& VM_ACCOUNT
))
178 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
181 static const struct super_operations shmem_ops
;
182 static const struct address_space_operations shmem_aops
;
183 static const struct file_operations shmem_file_operations
;
184 static const struct inode_operations shmem_inode_operations
;
185 static const struct inode_operations shmem_dir_inode_operations
;
186 static const struct inode_operations shmem_special_inode_operations
;
187 static struct vm_operations_struct shmem_vm_ops
;
189 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
190 .ra_pages
= 0, /* No readahead */
191 .capabilities
= BDI_CAP_NO_ACCT_DIRTY
| BDI_CAP_NO_WRITEBACK
,
192 .unplug_io_fn
= default_unplug_io_fn
,
195 static LIST_HEAD(shmem_swaplist
);
196 static DEFINE_SPINLOCK(shmem_swaplist_lock
);
198 static void shmem_free_blocks(struct inode
*inode
, long pages
)
200 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
201 if (sbinfo
->max_blocks
) {
202 spin_lock(&sbinfo
->stat_lock
);
203 sbinfo
->free_blocks
+= pages
;
204 inode
->i_blocks
-= pages
*BLOCKS_PER_PAGE
;
205 spin_unlock(&sbinfo
->stat_lock
);
210 * shmem_recalc_inode - recalculate the size of an inode
212 * @inode: inode to recalc
214 * We have to calculate the free blocks since the mm can drop
215 * undirtied hole pages behind our back.
217 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
218 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
220 * It has to be called with the spinlock held.
222 static void shmem_recalc_inode(struct inode
*inode
)
224 struct shmem_inode_info
*info
= SHMEM_I(inode
);
227 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
229 info
->alloced
-= freed
;
230 shmem_unacct_blocks(info
->flags
, freed
);
231 shmem_free_blocks(inode
, freed
);
236 * shmem_swp_entry - find the swap vector position in the info structure
238 * @info: info structure for the inode
239 * @index: index of the page to find
240 * @page: optional page to add to the structure. Has to be preset to
243 * If there is no space allocated yet it will return NULL when
244 * page is NULL, else it will use the page for the needed block,
245 * setting it to NULL on return to indicate that it has been used.
247 * The swap vector is organized the following way:
249 * There are SHMEM_NR_DIRECT entries directly stored in the
250 * shmem_inode_info structure. So small files do not need an addional
253 * For pages with index > SHMEM_NR_DIRECT there is the pointer
254 * i_indirect which points to a page which holds in the first half
255 * doubly indirect blocks, in the second half triple indirect blocks:
257 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
258 * following layout (for SHMEM_NR_DIRECT == 16):
260 * i_indirect -> dir --> 16-19
273 static swp_entry_t
*shmem_swp_entry(struct shmem_inode_info
*info
, unsigned long index
, struct page
**page
)
275 unsigned long offset
;
279 if (index
< SHMEM_NR_DIRECT
) {
280 shmem_swp_balance_unmap();
281 return info
->i_direct
+index
;
283 if (!info
->i_indirect
) {
285 info
->i_indirect
= *page
;
288 return NULL
; /* need another page */
291 index
-= SHMEM_NR_DIRECT
;
292 offset
= index
% ENTRIES_PER_PAGE
;
293 index
/= ENTRIES_PER_PAGE
;
294 dir
= shmem_dir_map(info
->i_indirect
);
296 if (index
>= ENTRIES_PER_PAGE
/2) {
297 index
-= ENTRIES_PER_PAGE
/2;
298 dir
+= ENTRIES_PER_PAGE
/2 + index
/ENTRIES_PER_PAGE
;
299 index
%= ENTRIES_PER_PAGE
;
306 shmem_dir_unmap(dir
);
307 return NULL
; /* need another page */
309 shmem_dir_unmap(dir
);
310 dir
= shmem_dir_map(subdir
);
316 if (!page
|| !(subdir
= *page
)) {
317 shmem_dir_unmap(dir
);
318 return NULL
; /* need a page */
323 shmem_dir_unmap(dir
);
324 return shmem_swp_map(subdir
) + offset
;
327 static void shmem_swp_set(struct shmem_inode_info
*info
, swp_entry_t
*entry
, unsigned long value
)
329 long incdec
= value
? 1: -1;
332 info
->swapped
+= incdec
;
333 if ((unsigned long)(entry
- info
->i_direct
) >= SHMEM_NR_DIRECT
) {
334 struct page
*page
= kmap_atomic_to_page(entry
);
335 set_page_private(page
, page_private(page
) + incdec
);
340 * shmem_swp_alloc - get the position of the swap entry for the page.
341 * If it does not exist allocate the entry.
343 * @info: info structure for the inode
344 * @index: index of the page to find
345 * @sgp: check and recheck i_size? skip allocation?
347 static swp_entry_t
*shmem_swp_alloc(struct shmem_inode_info
*info
, unsigned long index
, enum sgp_type sgp
)
349 struct inode
*inode
= &info
->vfs_inode
;
350 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
351 struct page
*page
= NULL
;
354 if (sgp
!= SGP_WRITE
&&
355 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
356 return ERR_PTR(-EINVAL
);
358 while (!(entry
= shmem_swp_entry(info
, index
, &page
))) {
360 return shmem_swp_map(ZERO_PAGE(0));
362 * Test free_blocks against 1 not 0, since we have 1 data
363 * page (and perhaps indirect index pages) yet to allocate:
364 * a waste to allocate index if we cannot allocate data.
366 if (sbinfo
->max_blocks
) {
367 spin_lock(&sbinfo
->stat_lock
);
368 if (sbinfo
->free_blocks
<= 1) {
369 spin_unlock(&sbinfo
->stat_lock
);
370 return ERR_PTR(-ENOSPC
);
372 sbinfo
->free_blocks
--;
373 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
374 spin_unlock(&sbinfo
->stat_lock
);
377 spin_unlock(&info
->lock
);
378 page
= shmem_dir_alloc(mapping_gfp_mask(inode
->i_mapping
));
380 set_page_private(page
, 0);
381 spin_lock(&info
->lock
);
384 shmem_free_blocks(inode
, 1);
385 return ERR_PTR(-ENOMEM
);
387 if (sgp
!= SGP_WRITE
&&
388 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
389 entry
= ERR_PTR(-EINVAL
);
392 if (info
->next_index
<= index
)
393 info
->next_index
= index
+ 1;
396 /* another task gave its page, or truncated the file */
397 shmem_free_blocks(inode
, 1);
398 shmem_dir_free(page
);
400 if (info
->next_index
<= index
&& !IS_ERR(entry
))
401 info
->next_index
= index
+ 1;
406 * shmem_free_swp - free some swap entries in a directory
408 * @dir: pointer to the directory
409 * @edir: pointer after last entry of the directory
410 * @punch_lock: pointer to spinlock when needed for the holepunch case
412 static int shmem_free_swp(swp_entry_t
*dir
, swp_entry_t
*edir
,
413 spinlock_t
*punch_lock
)
415 spinlock_t
*punch_unlock
= NULL
;
419 for (ptr
= dir
; ptr
< edir
; ptr
++) {
421 if (unlikely(punch_lock
)) {
422 punch_unlock
= punch_lock
;
424 spin_lock(punch_unlock
);
428 free_swap_and_cache(*ptr
);
429 *ptr
= (swp_entry_t
){0};
434 spin_unlock(punch_unlock
);
438 static int shmem_map_and_free_swp(struct page
*subdir
, int offset
,
439 int limit
, struct page
***dir
, spinlock_t
*punch_lock
)
444 ptr
= shmem_swp_map(subdir
);
445 for (; offset
< limit
; offset
+= LATENCY_LIMIT
) {
446 int size
= limit
- offset
;
447 if (size
> LATENCY_LIMIT
)
448 size
= LATENCY_LIMIT
;
449 freed
+= shmem_free_swp(ptr
+offset
, ptr
+offset
+size
,
451 if (need_resched()) {
452 shmem_swp_unmap(ptr
);
454 shmem_dir_unmap(*dir
);
458 ptr
= shmem_swp_map(subdir
);
461 shmem_swp_unmap(ptr
);
465 static void shmem_free_pages(struct list_head
*next
)
471 page
= container_of(next
, struct page
, lru
);
473 shmem_dir_free(page
);
475 if (freed
>= LATENCY_LIMIT
) {
482 static void shmem_truncate_range(struct inode
*inode
, loff_t start
, loff_t end
)
484 struct shmem_inode_info
*info
= SHMEM_I(inode
);
489 unsigned long diroff
;
495 LIST_HEAD(pages_to_free
);
496 long nr_pages_to_free
= 0;
497 long nr_swaps_freed
= 0;
501 spinlock_t
*needs_lock
;
502 spinlock_t
*punch_lock
;
503 unsigned long upper_limit
;
505 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
506 idx
= (start
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
507 if (idx
>= info
->next_index
)
510 spin_lock(&info
->lock
);
511 info
->flags
|= SHMEM_TRUNCATE
;
512 if (likely(end
== (loff_t
) -1)) {
513 limit
= info
->next_index
;
514 upper_limit
= SHMEM_MAX_INDEX
;
515 info
->next_index
= idx
;
519 if (end
+ 1 >= inode
->i_size
) { /* we may free a little more */
520 limit
= (inode
->i_size
+ PAGE_CACHE_SIZE
- 1) >>
522 upper_limit
= SHMEM_MAX_INDEX
;
524 limit
= (end
+ 1) >> PAGE_CACHE_SHIFT
;
527 needs_lock
= &info
->lock
;
531 topdir
= info
->i_indirect
;
532 if (topdir
&& idx
<= SHMEM_NR_DIRECT
&& !punch_hole
) {
533 info
->i_indirect
= NULL
;
535 list_add(&topdir
->lru
, &pages_to_free
);
537 spin_unlock(&info
->lock
);
539 if (info
->swapped
&& idx
< SHMEM_NR_DIRECT
) {
540 ptr
= info
->i_direct
;
542 if (size
> SHMEM_NR_DIRECT
)
543 size
= SHMEM_NR_DIRECT
;
544 nr_swaps_freed
= shmem_free_swp(ptr
+idx
, ptr
+size
, needs_lock
);
548 * If there are no indirect blocks or we are punching a hole
549 * below indirect blocks, nothing to be done.
551 if (!topdir
|| limit
<= SHMEM_NR_DIRECT
)
555 * The truncation case has already dropped info->lock, and we're safe
556 * because i_size and next_index have already been lowered, preventing
557 * access beyond. But in the punch_hole case, we still need to take
558 * the lock when updating the swap directory, because there might be
559 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
560 * shmem_writepage. However, whenever we find we can remove a whole
561 * directory page (not at the misaligned start or end of the range),
562 * we first NULLify its pointer in the level above, and then have no
563 * need to take the lock when updating its contents: needs_lock and
564 * punch_lock (either pointing to info->lock or NULL) manage this.
567 upper_limit
-= SHMEM_NR_DIRECT
;
568 limit
-= SHMEM_NR_DIRECT
;
569 idx
= (idx
> SHMEM_NR_DIRECT
)? (idx
- SHMEM_NR_DIRECT
): 0;
570 offset
= idx
% ENTRIES_PER_PAGE
;
573 dir
= shmem_dir_map(topdir
);
574 stage
= ENTRIES_PER_PAGEPAGE
/2;
575 if (idx
< ENTRIES_PER_PAGEPAGE
/2) {
577 diroff
= idx
/ENTRIES_PER_PAGE
;
579 dir
+= ENTRIES_PER_PAGE
/2;
580 dir
+= (idx
- ENTRIES_PER_PAGEPAGE
/2)/ENTRIES_PER_PAGEPAGE
;
582 stage
+= ENTRIES_PER_PAGEPAGE
;
585 diroff
= ((idx
- ENTRIES_PER_PAGEPAGE
/2) %
586 ENTRIES_PER_PAGEPAGE
) / ENTRIES_PER_PAGE
;
587 if (!diroff
&& !offset
&& upper_limit
>= stage
) {
589 spin_lock(needs_lock
);
591 spin_unlock(needs_lock
);
596 list_add(&middir
->lru
, &pages_to_free
);
598 shmem_dir_unmap(dir
);
599 dir
= shmem_dir_map(middir
);
607 for (; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, diroff
++) {
608 if (unlikely(idx
== stage
)) {
609 shmem_dir_unmap(dir
);
610 dir
= shmem_dir_map(topdir
) +
611 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
614 idx
+= ENTRIES_PER_PAGEPAGE
;
618 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
621 needs_lock
= &info
->lock
;
622 if (upper_limit
>= stage
) {
624 spin_lock(needs_lock
);
626 spin_unlock(needs_lock
);
631 list_add(&middir
->lru
, &pages_to_free
);
633 shmem_dir_unmap(dir
);
635 dir
= shmem_dir_map(middir
);
638 punch_lock
= needs_lock
;
639 subdir
= dir
[diroff
];
640 if (subdir
&& !offset
&& upper_limit
-idx
>= ENTRIES_PER_PAGE
) {
642 spin_lock(needs_lock
);
644 spin_unlock(needs_lock
);
649 list_add(&subdir
->lru
, &pages_to_free
);
651 if (subdir
&& page_private(subdir
) /* has swap entries */) {
653 if (size
> ENTRIES_PER_PAGE
)
654 size
= ENTRIES_PER_PAGE
;
655 freed
= shmem_map_and_free_swp(subdir
,
656 offset
, size
, &dir
, punch_lock
);
658 dir
= shmem_dir_map(middir
);
659 nr_swaps_freed
+= freed
;
660 if (offset
|| punch_lock
) {
661 spin_lock(&info
->lock
);
662 set_page_private(subdir
,
663 page_private(subdir
) - freed
);
664 spin_unlock(&info
->lock
);
666 BUG_ON(page_private(subdir
) != freed
);
671 shmem_dir_unmap(dir
);
673 if (inode
->i_mapping
->nrpages
&& (info
->flags
& SHMEM_PAGEIN
)) {
675 * Call truncate_inode_pages again: racing shmem_unuse_inode
676 * may have swizzled a page in from swap since vmtruncate or
677 * generic_delete_inode did it, before we lowered next_index.
678 * Also, though shmem_getpage checks i_size before adding to
679 * cache, no recheck after: so fix the narrow window there too.
681 * Recalling truncate_inode_pages_range and unmap_mapping_range
682 * every time for punch_hole (which never got a chance to clear
683 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
684 * yet hardly ever necessary: try to optimize them out later.
686 truncate_inode_pages_range(inode
->i_mapping
, start
, end
);
688 unmap_mapping_range(inode
->i_mapping
, start
,
692 spin_lock(&info
->lock
);
693 info
->flags
&= ~SHMEM_TRUNCATE
;
694 info
->swapped
-= nr_swaps_freed
;
695 if (nr_pages_to_free
)
696 shmem_free_blocks(inode
, nr_pages_to_free
);
697 shmem_recalc_inode(inode
);
698 spin_unlock(&info
->lock
);
701 * Empty swap vector directory pages to be freed?
703 if (!list_empty(&pages_to_free
)) {
704 pages_to_free
.prev
->next
= NULL
;
705 shmem_free_pages(pages_to_free
.next
);
709 static void shmem_truncate(struct inode
*inode
)
711 shmem_truncate_range(inode
, inode
->i_size
, (loff_t
)-1);
714 static int shmem_notify_change(struct dentry
*dentry
, struct iattr
*attr
)
716 struct inode
*inode
= dentry
->d_inode
;
717 struct page
*page
= NULL
;
720 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
721 if (attr
->ia_size
< inode
->i_size
) {
723 * If truncating down to a partial page, then
724 * if that page is already allocated, hold it
725 * in memory until the truncation is over, so
726 * truncate_partial_page cannnot miss it were
727 * it assigned to swap.
729 if (attr
->ia_size
& (PAGE_CACHE_SIZE
-1)) {
730 (void) shmem_getpage(inode
,
731 attr
->ia_size
>>PAGE_CACHE_SHIFT
,
732 &page
, SGP_READ
, NULL
);
735 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
736 * detect if any pages might have been added to cache
737 * after truncate_inode_pages. But we needn't bother
738 * if it's being fully truncated to zero-length: the
739 * nrpages check is efficient enough in that case.
742 struct shmem_inode_info
*info
= SHMEM_I(inode
);
743 spin_lock(&info
->lock
);
744 info
->flags
&= ~SHMEM_PAGEIN
;
745 spin_unlock(&info
->lock
);
750 error
= inode_change_ok(inode
, attr
);
752 error
= inode_setattr(inode
, attr
);
753 #ifdef CONFIG_TMPFS_POSIX_ACL
754 if (!error
&& (attr
->ia_valid
& ATTR_MODE
))
755 error
= generic_acl_chmod(inode
, &shmem_acl_ops
);
758 page_cache_release(page
);
762 static void shmem_delete_inode(struct inode
*inode
)
764 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
765 struct shmem_inode_info
*info
= SHMEM_I(inode
);
767 if (inode
->i_op
->truncate
== shmem_truncate
) {
768 truncate_inode_pages(inode
->i_mapping
, 0);
769 shmem_unacct_size(info
->flags
, inode
->i_size
);
771 shmem_truncate(inode
);
772 if (!list_empty(&info
->swaplist
)) {
773 spin_lock(&shmem_swaplist_lock
);
774 list_del_init(&info
->swaplist
);
775 spin_unlock(&shmem_swaplist_lock
);
778 BUG_ON(inode
->i_blocks
);
779 if (sbinfo
->max_inodes
) {
780 spin_lock(&sbinfo
->stat_lock
);
781 sbinfo
->free_inodes
++;
782 spin_unlock(&sbinfo
->stat_lock
);
787 static inline int shmem_find_swp(swp_entry_t entry
, swp_entry_t
*dir
, swp_entry_t
*edir
)
791 for (ptr
= dir
; ptr
< edir
; ptr
++) {
792 if (ptr
->val
== entry
.val
)
798 static int shmem_unuse_inode(struct shmem_inode_info
*info
, swp_entry_t entry
, struct page
*page
)
811 ptr
= info
->i_direct
;
812 spin_lock(&info
->lock
);
813 limit
= info
->next_index
;
815 if (size
> SHMEM_NR_DIRECT
)
816 size
= SHMEM_NR_DIRECT
;
817 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
819 shmem_swp_balance_unmap();
822 if (!info
->i_indirect
)
825 dir
= shmem_dir_map(info
->i_indirect
);
826 stage
= SHMEM_NR_DIRECT
+ ENTRIES_PER_PAGEPAGE
/2;
828 for (idx
= SHMEM_NR_DIRECT
; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, dir
++) {
829 if (unlikely(idx
== stage
)) {
830 shmem_dir_unmap(dir
-1);
831 dir
= shmem_dir_map(info
->i_indirect
) +
832 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
835 idx
+= ENTRIES_PER_PAGEPAGE
;
839 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
841 shmem_dir_unmap(dir
);
842 dir
= shmem_dir_map(subdir
);
845 if (subdir
&& page_private(subdir
)) {
846 ptr
= shmem_swp_map(subdir
);
848 if (size
> ENTRIES_PER_PAGE
)
849 size
= ENTRIES_PER_PAGE
;
850 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
852 shmem_dir_unmap(dir
);
855 shmem_swp_unmap(ptr
);
859 shmem_dir_unmap(dir
-1);
861 spin_unlock(&info
->lock
);
865 inode
= &info
->vfs_inode
;
866 if (move_from_swap_cache(page
, idx
, inode
->i_mapping
) == 0) {
867 info
->flags
|= SHMEM_PAGEIN
;
868 shmem_swp_set(info
, ptr
+ offset
, 0);
870 shmem_swp_unmap(ptr
);
871 spin_unlock(&info
->lock
);
873 * Decrement swap count even when the entry is left behind:
874 * try_to_unuse will skip over mms, then reincrement count.
881 * shmem_unuse() search for an eventually swapped out shmem page.
883 int shmem_unuse(swp_entry_t entry
, struct page
*page
)
885 struct list_head
*p
, *next
;
886 struct shmem_inode_info
*info
;
889 spin_lock(&shmem_swaplist_lock
);
890 list_for_each_safe(p
, next
, &shmem_swaplist
) {
891 info
= list_entry(p
, struct shmem_inode_info
, swaplist
);
893 list_del_init(&info
->swaplist
);
894 else if (shmem_unuse_inode(info
, entry
, page
)) {
895 /* move head to start search for next from here */
896 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
901 spin_unlock(&shmem_swaplist_lock
);
906 * Move the page from the page cache to the swap cache.
908 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
910 struct shmem_inode_info
*info
;
911 swp_entry_t
*entry
, swap
;
912 struct address_space
*mapping
;
916 BUG_ON(!PageLocked(page
));
917 BUG_ON(page_mapped(page
));
919 mapping
= page
->mapping
;
921 inode
= mapping
->host
;
922 info
= SHMEM_I(inode
);
923 if (info
->flags
& VM_LOCKED
)
925 swap
= get_swap_page();
929 spin_lock(&info
->lock
);
930 shmem_recalc_inode(inode
);
931 if (index
>= info
->next_index
) {
932 BUG_ON(!(info
->flags
& SHMEM_TRUNCATE
));
935 entry
= shmem_swp_entry(info
, index
, NULL
);
939 if (move_to_swap_cache(page
, swap
) == 0) {
940 shmem_swp_set(info
, entry
, swap
.val
);
941 shmem_swp_unmap(entry
);
942 spin_unlock(&info
->lock
);
943 if (list_empty(&info
->swaplist
)) {
944 spin_lock(&shmem_swaplist_lock
);
945 /* move instead of add in case we're racing */
946 list_move_tail(&info
->swaplist
, &shmem_swaplist
);
947 spin_unlock(&shmem_swaplist_lock
);
953 shmem_swp_unmap(entry
);
955 spin_unlock(&info
->lock
);
958 set_page_dirty(page
);
959 return AOP_WRITEPAGE_ACTIVATE
; /* Return with the page locked */
963 static inline int shmem_parse_mpol(char *value
, int *policy
, nodemask_t
*policy_nodes
)
965 char *nodelist
= strchr(value
, ':');
969 /* NUL-terminate policy string */
971 if (nodelist_parse(nodelist
, *policy_nodes
))
973 if (!nodes_subset(*policy_nodes
, node_online_map
))
976 if (!strcmp(value
, "default")) {
977 *policy
= MPOL_DEFAULT
;
978 /* Don't allow a nodelist */
981 } else if (!strcmp(value
, "prefer")) {
982 *policy
= MPOL_PREFERRED
;
983 /* Insist on a nodelist of one node only */
985 char *rest
= nodelist
;
986 while (isdigit(*rest
))
991 } else if (!strcmp(value
, "bind")) {
993 /* Insist on a nodelist */
996 } else if (!strcmp(value
, "interleave")) {
997 *policy
= MPOL_INTERLEAVE
;
998 /* Default to nodes online if no nodelist */
1000 *policy_nodes
= node_online_map
;
1004 /* Restore string for error message */
1010 static struct page
*shmem_swapin_async(struct shared_policy
*p
,
1011 swp_entry_t entry
, unsigned long idx
)
1014 struct vm_area_struct pvma
;
1016 /* Create a pseudo vma that just contains the policy */
1017 memset(&pvma
, 0, sizeof(struct vm_area_struct
));
1018 pvma
.vm_end
= PAGE_SIZE
;
1019 pvma
.vm_pgoff
= idx
;
1020 pvma
.vm_policy
= mpol_shared_policy_lookup(p
, idx
);
1021 page
= read_swap_cache_async(entry
, &pvma
, 0);
1022 mpol_free(pvma
.vm_policy
);
1026 struct page
*shmem_swapin(struct shmem_inode_info
*info
, swp_entry_t entry
,
1029 struct shared_policy
*p
= &info
->policy
;
1032 unsigned long offset
;
1034 num
= valid_swaphandles(entry
, &offset
);
1035 for (i
= 0; i
< num
; offset
++, i
++) {
1036 page
= shmem_swapin_async(p
,
1037 swp_entry(swp_type(entry
), offset
), idx
);
1040 page_cache_release(page
);
1042 lru_add_drain(); /* Push any new pages onto the LRU now */
1043 return shmem_swapin_async(p
, entry
, idx
);
1046 static struct page
*
1047 shmem_alloc_page(gfp_t gfp
, struct shmem_inode_info
*info
,
1050 struct vm_area_struct pvma
;
1053 memset(&pvma
, 0, sizeof(struct vm_area_struct
));
1054 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, idx
);
1055 pvma
.vm_pgoff
= idx
;
1056 pvma
.vm_end
= PAGE_SIZE
;
1057 page
= alloc_page_vma(gfp
| __GFP_ZERO
, &pvma
, 0);
1058 mpol_free(pvma
.vm_policy
);
1062 static inline int shmem_parse_mpol(char *value
, int *policy
, nodemask_t
*policy_nodes
)
1067 static inline struct page
*
1068 shmem_swapin(struct shmem_inode_info
*info
,swp_entry_t entry
,unsigned long idx
)
1070 swapin_readahead(entry
, 0, NULL
);
1071 return read_swap_cache_async(entry
, NULL
, 0);
1074 static inline struct page
*
1075 shmem_alloc_page(gfp_t gfp
,struct shmem_inode_info
*info
, unsigned long idx
)
1077 return alloc_page(gfp
| __GFP_ZERO
);
1082 * shmem_getpage - either get the page from swap or allocate a new one
1084 * If we allocate a new one we do not mark it dirty. That's up to the
1085 * vm. If we swap it in we mark it dirty since we also free the swap
1086 * entry since a page cannot live in both the swap and page cache
1088 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
1089 struct page
**pagep
, enum sgp_type sgp
, int *type
)
1091 struct address_space
*mapping
= inode
->i_mapping
;
1092 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1093 struct shmem_sb_info
*sbinfo
;
1094 struct page
*filepage
= *pagep
;
1095 struct page
*swappage
;
1100 if (idx
>= SHMEM_MAX_INDEX
)
1103 * Normally, filepage is NULL on entry, and either found
1104 * uptodate immediately, or allocated and zeroed, or read
1105 * in under swappage, which is then assigned to filepage.
1106 * But shmem_readpage and shmem_prepare_write pass in a locked
1107 * filepage, which may be found not uptodate by other callers
1108 * too, and may need to be copied from the swappage read in.
1112 filepage
= find_lock_page(mapping
, idx
);
1113 if (filepage
&& PageUptodate(filepage
))
1116 if (sgp
== SGP_QUICK
)
1119 spin_lock(&info
->lock
);
1120 shmem_recalc_inode(inode
);
1121 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1122 if (IS_ERR(entry
)) {
1123 spin_unlock(&info
->lock
);
1124 error
= PTR_ERR(entry
);
1130 /* Look it up and read it in.. */
1131 swappage
= lookup_swap_cache(swap
);
1133 shmem_swp_unmap(entry
);
1134 /* here we actually do the io */
1135 if (type
&& *type
== VM_FAULT_MINOR
) {
1136 __count_vm_event(PGMAJFAULT
);
1137 *type
= VM_FAULT_MAJOR
;
1139 spin_unlock(&info
->lock
);
1140 swappage
= shmem_swapin(info
, swap
, idx
);
1142 spin_lock(&info
->lock
);
1143 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1145 error
= PTR_ERR(entry
);
1147 if (entry
->val
== swap
.val
)
1149 shmem_swp_unmap(entry
);
1151 spin_unlock(&info
->lock
);
1156 wait_on_page_locked(swappage
);
1157 page_cache_release(swappage
);
1161 /* We have to do this with page locked to prevent races */
1162 if (TestSetPageLocked(swappage
)) {
1163 shmem_swp_unmap(entry
);
1164 spin_unlock(&info
->lock
);
1165 wait_on_page_locked(swappage
);
1166 page_cache_release(swappage
);
1169 if (PageWriteback(swappage
)) {
1170 shmem_swp_unmap(entry
);
1171 spin_unlock(&info
->lock
);
1172 wait_on_page_writeback(swappage
);
1173 unlock_page(swappage
);
1174 page_cache_release(swappage
);
1177 if (!PageUptodate(swappage
)) {
1178 shmem_swp_unmap(entry
);
1179 spin_unlock(&info
->lock
);
1180 unlock_page(swappage
);
1181 page_cache_release(swappage
);
1187 shmem_swp_set(info
, entry
, 0);
1188 shmem_swp_unmap(entry
);
1189 delete_from_swap_cache(swappage
);
1190 spin_unlock(&info
->lock
);
1191 copy_highpage(filepage
, swappage
);
1192 unlock_page(swappage
);
1193 page_cache_release(swappage
);
1194 flush_dcache_page(filepage
);
1195 SetPageUptodate(filepage
);
1196 set_page_dirty(filepage
);
1198 } else if (!(error
= move_from_swap_cache(
1199 swappage
, idx
, mapping
))) {
1200 info
->flags
|= SHMEM_PAGEIN
;
1201 shmem_swp_set(info
, entry
, 0);
1202 shmem_swp_unmap(entry
);
1203 spin_unlock(&info
->lock
);
1204 filepage
= swappage
;
1207 shmem_swp_unmap(entry
);
1208 spin_unlock(&info
->lock
);
1209 unlock_page(swappage
);
1210 page_cache_release(swappage
);
1211 if (error
== -ENOMEM
) {
1212 /* let kswapd refresh zone for GFP_ATOMICs */
1213 congestion_wait(WRITE
, HZ
/50);
1217 } else if (sgp
== SGP_READ
&& !filepage
) {
1218 shmem_swp_unmap(entry
);
1219 filepage
= find_get_page(mapping
, idx
);
1221 (!PageUptodate(filepage
) || TestSetPageLocked(filepage
))) {
1222 spin_unlock(&info
->lock
);
1223 wait_on_page_locked(filepage
);
1224 page_cache_release(filepage
);
1228 spin_unlock(&info
->lock
);
1230 shmem_swp_unmap(entry
);
1231 sbinfo
= SHMEM_SB(inode
->i_sb
);
1232 if (sbinfo
->max_blocks
) {
1233 spin_lock(&sbinfo
->stat_lock
);
1234 if (sbinfo
->free_blocks
== 0 ||
1235 shmem_acct_block(info
->flags
)) {
1236 spin_unlock(&sbinfo
->stat_lock
);
1237 spin_unlock(&info
->lock
);
1241 sbinfo
->free_blocks
--;
1242 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1243 spin_unlock(&sbinfo
->stat_lock
);
1244 } else if (shmem_acct_block(info
->flags
)) {
1245 spin_unlock(&info
->lock
);
1251 spin_unlock(&info
->lock
);
1252 filepage
= shmem_alloc_page(mapping_gfp_mask(mapping
),
1256 shmem_unacct_blocks(info
->flags
, 1);
1257 shmem_free_blocks(inode
, 1);
1262 spin_lock(&info
->lock
);
1263 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1265 error
= PTR_ERR(entry
);
1268 shmem_swp_unmap(entry
);
1270 if (error
|| swap
.val
|| 0 != add_to_page_cache_lru(
1271 filepage
, mapping
, idx
, GFP_ATOMIC
)) {
1272 spin_unlock(&info
->lock
);
1273 page_cache_release(filepage
);
1274 shmem_unacct_blocks(info
->flags
, 1);
1275 shmem_free_blocks(inode
, 1);
1281 info
->flags
|= SHMEM_PAGEIN
;
1285 spin_unlock(&info
->lock
);
1286 flush_dcache_page(filepage
);
1287 SetPageUptodate(filepage
);
1290 if (*pagep
!= filepage
) {
1291 unlock_page(filepage
);
1297 if (*pagep
!= filepage
) {
1298 unlock_page(filepage
);
1299 page_cache_release(filepage
);
1304 static struct page
*shmem_nopage(struct vm_area_struct
*vma
,
1305 unsigned long address
, int *type
)
1307 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1308 struct page
*page
= NULL
;
1312 idx
= (address
- vma
->vm_start
) >> PAGE_SHIFT
;
1313 idx
+= vma
->vm_pgoff
;
1314 idx
>>= PAGE_CACHE_SHIFT
- PAGE_SHIFT
;
1315 if (((loff_t
) idx
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
1316 return NOPAGE_SIGBUS
;
1318 error
= shmem_getpage(inode
, idx
, &page
, SGP_CACHE
, type
);
1320 return (error
== -ENOMEM
)? NOPAGE_OOM
: NOPAGE_SIGBUS
;
1322 mark_page_accessed(page
);
1326 static int shmem_populate(struct vm_area_struct
*vma
,
1327 unsigned long addr
, unsigned long len
,
1328 pgprot_t prot
, unsigned long pgoff
, int nonblock
)
1330 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1331 struct mm_struct
*mm
= vma
->vm_mm
;
1332 enum sgp_type sgp
= nonblock
? SGP_QUICK
: SGP_CACHE
;
1335 size
= (i_size_read(inode
) + PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1336 if (pgoff
>= size
|| pgoff
+ (len
>> PAGE_SHIFT
) > size
)
1339 while ((long) len
> 0) {
1340 struct page
*page
= NULL
;
1343 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1345 err
= shmem_getpage(inode
, pgoff
, &page
, sgp
, NULL
);
1348 /* Page may still be null, but only if nonblock was set. */
1350 mark_page_accessed(page
);
1351 err
= install_page(mm
, vma
, addr
, page
, prot
);
1353 page_cache_release(page
);
1356 } else if (vma
->vm_flags
& VM_NONLINEAR
) {
1357 /* No page was found just because we can't read it in
1358 * now (being here implies nonblock != 0), but the page
1359 * may exist, so set the PTE to fault it in later. */
1360 err
= install_file_pte(mm
, vma
, addr
, pgoff
, prot
);
1373 int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*new)
1375 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1376 return mpol_set_shared_policy(&SHMEM_I(i
)->policy
, vma
, new);
1380 shmem_get_policy(struct vm_area_struct
*vma
, unsigned long addr
)
1382 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1385 idx
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1386 return mpol_shared_policy_lookup(&SHMEM_I(i
)->policy
, idx
);
1390 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1392 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1393 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1394 int retval
= -ENOMEM
;
1396 spin_lock(&info
->lock
);
1397 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1398 if (!user_shm_lock(inode
->i_size
, user
))
1400 info
->flags
|= VM_LOCKED
;
1402 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1403 user_shm_unlock(inode
->i_size
, user
);
1404 info
->flags
&= ~VM_LOCKED
;
1408 spin_unlock(&info
->lock
);
1412 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1414 file_accessed(file
);
1415 vma
->vm_ops
= &shmem_vm_ops
;
1419 static struct inode
*
1420 shmem_get_inode(struct super_block
*sb
, int mode
, dev_t dev
)
1422 struct inode
*inode
;
1423 struct shmem_inode_info
*info
;
1424 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1426 if (sbinfo
->max_inodes
) {
1427 spin_lock(&sbinfo
->stat_lock
);
1428 if (!sbinfo
->free_inodes
) {
1429 spin_unlock(&sbinfo
->stat_lock
);
1432 sbinfo
->free_inodes
--;
1433 spin_unlock(&sbinfo
->stat_lock
);
1436 inode
= new_inode(sb
);
1438 inode
->i_mode
= mode
;
1439 inode
->i_uid
= current
->fsuid
;
1440 inode
->i_gid
= current
->fsgid
;
1441 inode
->i_blocks
= 0;
1442 inode
->i_mapping
->a_ops
= &shmem_aops
;
1443 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1444 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1445 inode
->i_generation
= get_seconds();
1446 info
= SHMEM_I(inode
);
1447 memset(info
, 0, (char *)inode
- (char *)info
);
1448 spin_lock_init(&info
->lock
);
1449 INIT_LIST_HEAD(&info
->swaplist
);
1451 switch (mode
& S_IFMT
) {
1453 inode
->i_op
= &shmem_special_inode_operations
;
1454 init_special_inode(inode
, mode
, dev
);
1457 inode
->i_op
= &shmem_inode_operations
;
1458 inode
->i_fop
= &shmem_file_operations
;
1459 mpol_shared_policy_init(&info
->policy
, sbinfo
->policy
,
1460 &sbinfo
->policy_nodes
);
1464 /* Some things misbehave if size == 0 on a directory */
1465 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1466 inode
->i_op
= &shmem_dir_inode_operations
;
1467 inode
->i_fop
= &simple_dir_operations
;
1471 * Must not load anything in the rbtree,
1472 * mpol_free_shared_policy will not be called.
1474 mpol_shared_policy_init(&info
->policy
, MPOL_DEFAULT
,
1478 } else if (sbinfo
->max_inodes
) {
1479 spin_lock(&sbinfo
->stat_lock
);
1480 sbinfo
->free_inodes
++;
1481 spin_unlock(&sbinfo
->stat_lock
);
1487 static const struct inode_operations shmem_symlink_inode_operations
;
1488 static const struct inode_operations shmem_symlink_inline_operations
;
1491 * Normally tmpfs avoids the use of shmem_readpage and shmem_prepare_write;
1492 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1493 * below the loop driver, in the generic fashion that many filesystems support.
1495 static int shmem_readpage(struct file
*file
, struct page
*page
)
1497 struct inode
*inode
= page
->mapping
->host
;
1498 int error
= shmem_getpage(inode
, page
->index
, &page
, SGP_CACHE
, NULL
);
1504 shmem_prepare_write(struct file
*file
, struct page
*page
, unsigned offset
, unsigned to
)
1506 struct inode
*inode
= page
->mapping
->host
;
1507 return shmem_getpage(inode
, page
->index
, &page
, SGP_WRITE
, NULL
);
1511 shmem_file_write(struct file
*file
, const char __user
*buf
, size_t count
, loff_t
*ppos
)
1513 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1515 unsigned long written
;
1518 if ((ssize_t
) count
< 0)
1521 if (!access_ok(VERIFY_READ
, buf
, count
))
1524 mutex_lock(&inode
->i_mutex
);
1529 err
= generic_write_checks(file
, &pos
, &count
, 0);
1533 err
= remove_suid(file
->f_path
.dentry
);
1537 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
1540 struct page
*page
= NULL
;
1541 unsigned long bytes
, index
, offset
;
1545 offset
= (pos
& (PAGE_CACHE_SIZE
-1)); /* Within page */
1546 index
= pos
>> PAGE_CACHE_SHIFT
;
1547 bytes
= PAGE_CACHE_SIZE
- offset
;
1552 * We don't hold page lock across copy from user -
1553 * what would it guard against? - so no deadlock here.
1554 * But it still may be a good idea to prefault below.
1557 err
= shmem_getpage(inode
, index
, &page
, SGP_WRITE
, NULL
);
1562 if (PageHighMem(page
)) {
1563 volatile unsigned char dummy
;
1564 __get_user(dummy
, buf
);
1565 __get_user(dummy
, buf
+ bytes
- 1);
1567 kaddr
= kmap_atomic(page
, KM_USER0
);
1568 left
= __copy_from_user_inatomic(kaddr
+ offset
,
1570 kunmap_atomic(kaddr
, KM_USER0
);
1574 left
= __copy_from_user(kaddr
+ offset
, buf
, bytes
);
1582 if (pos
> inode
->i_size
)
1583 i_size_write(inode
, pos
);
1585 flush_dcache_page(page
);
1586 set_page_dirty(page
);
1587 mark_page_accessed(page
);
1588 page_cache_release(page
);
1598 * Our dirty pages are not counted in nr_dirty,
1599 * and we do not attempt to balance dirty pages.
1609 mutex_unlock(&inode
->i_mutex
);
1613 static void do_shmem_file_read(struct file
*filp
, loff_t
*ppos
, read_descriptor_t
*desc
, read_actor_t actor
)
1615 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
1616 struct address_space
*mapping
= inode
->i_mapping
;
1617 unsigned long index
, offset
;
1619 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1620 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1623 struct page
*page
= NULL
;
1624 unsigned long end_index
, nr
, ret
;
1625 loff_t i_size
= i_size_read(inode
);
1627 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1628 if (index
> end_index
)
1630 if (index
== end_index
) {
1631 nr
= i_size
& ~PAGE_CACHE_MASK
;
1636 desc
->error
= shmem_getpage(inode
, index
, &page
, SGP_READ
, NULL
);
1638 if (desc
->error
== -EINVAL
)
1644 * We must evaluate after, since reads (unlike writes)
1645 * are called without i_mutex protection against truncate
1647 nr
= PAGE_CACHE_SIZE
;
1648 i_size
= i_size_read(inode
);
1649 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1650 if (index
== end_index
) {
1651 nr
= i_size
& ~PAGE_CACHE_MASK
;
1654 page_cache_release(page
);
1662 * If users can be writing to this page using arbitrary
1663 * virtual addresses, take care about potential aliasing
1664 * before reading the page on the kernel side.
1666 if (mapping_writably_mapped(mapping
))
1667 flush_dcache_page(page
);
1669 * Mark the page accessed if we read the beginning.
1672 mark_page_accessed(page
);
1674 page
= ZERO_PAGE(0);
1675 page_cache_get(page
);
1679 * Ok, we have the page, and it's up-to-date, so
1680 * now we can copy it to user space...
1682 * The actor routine returns how many bytes were actually used..
1683 * NOTE! This may not be the same as how much of a user buffer
1684 * we filled up (we may be padding etc), so we can only update
1685 * "pos" here (the actor routine has to update the user buffer
1686 * pointers and the remaining count).
1688 ret
= actor(desc
, page
, offset
, nr
);
1690 index
+= offset
>> PAGE_CACHE_SHIFT
;
1691 offset
&= ~PAGE_CACHE_MASK
;
1693 page_cache_release(page
);
1694 if (ret
!= nr
|| !desc
->count
)
1700 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1701 file_accessed(filp
);
1704 static ssize_t
shmem_file_read(struct file
*filp
, char __user
*buf
, size_t count
, loff_t
*ppos
)
1706 read_descriptor_t desc
;
1708 if ((ssize_t
) count
< 0)
1710 if (!access_ok(VERIFY_WRITE
, buf
, count
))
1720 do_shmem_file_read(filp
, ppos
, &desc
, file_read_actor
);
1722 return desc
.written
;
1726 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1728 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1730 buf
->f_type
= TMPFS_MAGIC
;
1731 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1732 buf
->f_namelen
= NAME_MAX
;
1733 spin_lock(&sbinfo
->stat_lock
);
1734 if (sbinfo
->max_blocks
) {
1735 buf
->f_blocks
= sbinfo
->max_blocks
;
1736 buf
->f_bavail
= buf
->f_bfree
= sbinfo
->free_blocks
;
1738 if (sbinfo
->max_inodes
) {
1739 buf
->f_files
= sbinfo
->max_inodes
;
1740 buf
->f_ffree
= sbinfo
->free_inodes
;
1742 /* else leave those fields 0 like simple_statfs */
1743 spin_unlock(&sbinfo
->stat_lock
);
1748 * File creation. Allocate an inode, and we're done..
1751 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1753 struct inode
*inode
= shmem_get_inode(dir
->i_sb
, mode
, dev
);
1754 int error
= -ENOSPC
;
1757 error
= security_inode_init_security(inode
, dir
, NULL
, NULL
,
1760 if (error
!= -EOPNOTSUPP
) {
1765 error
= shmem_acl_init(inode
, dir
);
1770 if (dir
->i_mode
& S_ISGID
) {
1771 inode
->i_gid
= dir
->i_gid
;
1773 inode
->i_mode
|= S_ISGID
;
1775 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1776 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1777 d_instantiate(dentry
, inode
);
1778 dget(dentry
); /* Extra count - pin the dentry in core */
1783 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1787 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1793 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1794 struct nameidata
*nd
)
1796 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
1802 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
1804 struct inode
*inode
= old_dentry
->d_inode
;
1805 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
1808 * No ordinary (disk based) filesystem counts links as inodes;
1809 * but each new link needs a new dentry, pinning lowmem, and
1810 * tmpfs dentries cannot be pruned until they are unlinked.
1812 if (sbinfo
->max_inodes
) {
1813 spin_lock(&sbinfo
->stat_lock
);
1814 if (!sbinfo
->free_inodes
) {
1815 spin_unlock(&sbinfo
->stat_lock
);
1818 sbinfo
->free_inodes
--;
1819 spin_unlock(&sbinfo
->stat_lock
);
1822 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1823 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1825 atomic_inc(&inode
->i_count
); /* New dentry reference */
1826 dget(dentry
); /* Extra pinning count for the created dentry */
1827 d_instantiate(dentry
, inode
);
1831 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
1833 struct inode
*inode
= dentry
->d_inode
;
1835 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
)) {
1836 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
1837 if (sbinfo
->max_inodes
) {
1838 spin_lock(&sbinfo
->stat_lock
);
1839 sbinfo
->free_inodes
++;
1840 spin_unlock(&sbinfo
->stat_lock
);
1844 dir
->i_size
-= BOGO_DIRENT_SIZE
;
1845 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1847 dput(dentry
); /* Undo the count from "create" - this does all the work */
1851 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1853 if (!simple_empty(dentry
))
1856 drop_nlink(dentry
->d_inode
);
1858 return shmem_unlink(dir
, dentry
);
1862 * The VFS layer already does all the dentry stuff for rename,
1863 * we just have to decrement the usage count for the target if
1864 * it exists so that the VFS layer correctly free's it when it
1867 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
1869 struct inode
*inode
= old_dentry
->d_inode
;
1870 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
1872 if (!simple_empty(new_dentry
))
1875 if (new_dentry
->d_inode
) {
1876 (void) shmem_unlink(new_dir
, new_dentry
);
1878 drop_nlink(old_dir
);
1879 } else if (they_are_dirs
) {
1880 drop_nlink(old_dir
);
1884 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
1885 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
1886 old_dir
->i_ctime
= old_dir
->i_mtime
=
1887 new_dir
->i_ctime
= new_dir
->i_mtime
=
1888 inode
->i_ctime
= CURRENT_TIME
;
1892 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
1896 struct inode
*inode
;
1897 struct page
*page
= NULL
;
1899 struct shmem_inode_info
*info
;
1901 len
= strlen(symname
) + 1;
1902 if (len
> PAGE_CACHE_SIZE
)
1903 return -ENAMETOOLONG
;
1905 inode
= shmem_get_inode(dir
->i_sb
, S_IFLNK
|S_IRWXUGO
, 0);
1909 error
= security_inode_init_security(inode
, dir
, NULL
, NULL
,
1912 if (error
!= -EOPNOTSUPP
) {
1919 info
= SHMEM_I(inode
);
1920 inode
->i_size
= len
-1;
1921 if (len
<= (char *)inode
- (char *)info
) {
1923 memcpy(info
, symname
, len
);
1924 inode
->i_op
= &shmem_symlink_inline_operations
;
1926 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
1931 inode
->i_op
= &shmem_symlink_inode_operations
;
1932 kaddr
= kmap_atomic(page
, KM_USER0
);
1933 memcpy(kaddr
, symname
, len
);
1934 kunmap_atomic(kaddr
, KM_USER0
);
1935 set_page_dirty(page
);
1936 page_cache_release(page
);
1938 if (dir
->i_mode
& S_ISGID
)
1939 inode
->i_gid
= dir
->i_gid
;
1940 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1941 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1942 d_instantiate(dentry
, inode
);
1947 static void *shmem_follow_link_inline(struct dentry
*dentry
, struct nameidata
*nd
)
1949 nd_set_link(nd
, (char *)SHMEM_I(dentry
->d_inode
));
1953 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
1955 struct page
*page
= NULL
;
1956 int res
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
1957 nd_set_link(nd
, res
? ERR_PTR(res
) : kmap(page
));
1961 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
1963 if (!IS_ERR(nd_get_link(nd
))) {
1964 struct page
*page
= cookie
;
1966 mark_page_accessed(page
);
1967 page_cache_release(page
);
1971 static const struct inode_operations shmem_symlink_inline_operations
= {
1972 .readlink
= generic_readlink
,
1973 .follow_link
= shmem_follow_link_inline
,
1976 static const struct inode_operations shmem_symlink_inode_operations
= {
1977 .truncate
= shmem_truncate
,
1978 .readlink
= generic_readlink
,
1979 .follow_link
= shmem_follow_link
,
1980 .put_link
= shmem_put_link
,
1983 #ifdef CONFIG_TMPFS_POSIX_ACL
1985 * Superblocks without xattr inode operations will get security.* xattr
1986 * support from the VFS "for free". As soon as we have any other xattrs
1987 * like ACLs, we also need to implement the security.* handlers at
1988 * filesystem level, though.
1991 static size_t shmem_xattr_security_list(struct inode
*inode
, char *list
,
1992 size_t list_len
, const char *name
,
1995 return security_inode_listsecurity(inode
, list
, list_len
);
1998 static int shmem_xattr_security_get(struct inode
*inode
, const char *name
,
1999 void *buffer
, size_t size
)
2001 if (strcmp(name
, "") == 0)
2003 return security_inode_getsecurity(inode
, name
, buffer
, size
,
2007 static int shmem_xattr_security_set(struct inode
*inode
, const char *name
,
2008 const void *value
, size_t size
, int flags
)
2010 if (strcmp(name
, "") == 0)
2012 return security_inode_setsecurity(inode
, name
, value
, size
, flags
);
2015 static struct xattr_handler shmem_xattr_security_handler
= {
2016 .prefix
= XATTR_SECURITY_PREFIX
,
2017 .list
= shmem_xattr_security_list
,
2018 .get
= shmem_xattr_security_get
,
2019 .set
= shmem_xattr_security_set
,
2022 static struct xattr_handler
*shmem_xattr_handlers
[] = {
2023 &shmem_xattr_acl_access_handler
,
2024 &shmem_xattr_acl_default_handler
,
2025 &shmem_xattr_security_handler
,
2030 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2032 return ERR_PTR(-ESTALE
);
2035 static int shmem_match(struct inode
*ino
, void *vfh
)
2039 inum
= (inum
<< 32) | fh
[1];
2040 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2043 static struct dentry
*shmem_get_dentry(struct super_block
*sb
, void *vfh
)
2045 struct dentry
*de
= NULL
;
2046 struct inode
*inode
;
2049 inum
= (inum
<< 32) | fh
[1];
2051 inode
= ilookup5(sb
, (unsigned long)(inum
+fh
[0]), shmem_match
, vfh
);
2053 de
= d_find_alias(inode
);
2057 return de
? de
: ERR_PTR(-ESTALE
);
2060 static struct dentry
*shmem_decode_fh(struct super_block
*sb
, __u32
*fh
,
2062 int (*acceptable
)(void *context
, struct dentry
*de
),
2066 return ERR_PTR(-ESTALE
);
2068 return sb
->s_export_op
->find_exported_dentry(sb
, fh
, NULL
, acceptable
,
2072 static int shmem_encode_fh(struct dentry
*dentry
, __u32
*fh
, int *len
,
2075 struct inode
*inode
= dentry
->d_inode
;
2080 if (hlist_unhashed(&inode
->i_hash
)) {
2081 /* Unfortunately insert_inode_hash is not idempotent,
2082 * so as we hash inodes here rather than at creation
2083 * time, we need a lock to ensure we only try
2086 static DEFINE_SPINLOCK(lock
);
2088 if (hlist_unhashed(&inode
->i_hash
))
2089 __insert_inode_hash(inode
,
2090 inode
->i_ino
+ inode
->i_generation
);
2094 fh
[0] = inode
->i_generation
;
2095 fh
[1] = inode
->i_ino
;
2096 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2102 static struct export_operations shmem_export_ops
= {
2103 .get_parent
= shmem_get_parent
,
2104 .get_dentry
= shmem_get_dentry
,
2105 .encode_fh
= shmem_encode_fh
,
2106 .decode_fh
= shmem_decode_fh
,
2109 static int shmem_parse_options(char *options
, int *mode
, uid_t
*uid
,
2110 gid_t
*gid
, unsigned long *blocks
, unsigned long *inodes
,
2111 int *policy
, nodemask_t
*policy_nodes
)
2113 char *this_char
, *value
, *rest
;
2115 while (options
!= NULL
) {
2116 this_char
= options
;
2119 * NUL-terminate this option: unfortunately,
2120 * mount options form a comma-separated list,
2121 * but mpol's nodelist may also contain commas.
2123 options
= strchr(options
, ',');
2124 if (options
== NULL
)
2127 if (!isdigit(*options
)) {
2134 if ((value
= strchr(this_char
,'=')) != NULL
) {
2138 "tmpfs: No value for mount option '%s'\n",
2143 if (!strcmp(this_char
,"size")) {
2144 unsigned long long size
;
2145 size
= memparse(value
,&rest
);
2147 size
<<= PAGE_SHIFT
;
2148 size
*= totalram_pages
;
2154 *blocks
= size
>> PAGE_CACHE_SHIFT
;
2155 } else if (!strcmp(this_char
,"nr_blocks")) {
2156 *blocks
= memparse(value
,&rest
);
2159 } else if (!strcmp(this_char
,"nr_inodes")) {
2160 *inodes
= memparse(value
,&rest
);
2163 } else if (!strcmp(this_char
,"mode")) {
2166 *mode
= simple_strtoul(value
,&rest
,8);
2169 } else if (!strcmp(this_char
,"uid")) {
2172 *uid
= simple_strtoul(value
,&rest
,0);
2175 } else if (!strcmp(this_char
,"gid")) {
2178 *gid
= simple_strtoul(value
,&rest
,0);
2181 } else if (!strcmp(this_char
,"mpol")) {
2182 if (shmem_parse_mpol(value
,policy
,policy_nodes
))
2185 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2193 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2199 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2201 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2202 unsigned long max_blocks
= sbinfo
->max_blocks
;
2203 unsigned long max_inodes
= sbinfo
->max_inodes
;
2204 int policy
= sbinfo
->policy
;
2205 nodemask_t policy_nodes
= sbinfo
->policy_nodes
;
2206 unsigned long blocks
;
2207 unsigned long inodes
;
2208 int error
= -EINVAL
;
2210 if (shmem_parse_options(data
, NULL
, NULL
, NULL
, &max_blocks
,
2211 &max_inodes
, &policy
, &policy_nodes
))
2214 spin_lock(&sbinfo
->stat_lock
);
2215 blocks
= sbinfo
->max_blocks
- sbinfo
->free_blocks
;
2216 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2217 if (max_blocks
< blocks
)
2219 if (max_inodes
< inodes
)
2222 * Those tests also disallow limited->unlimited while any are in
2223 * use, so i_blocks will always be zero when max_blocks is zero;
2224 * but we must separately disallow unlimited->limited, because
2225 * in that case we have no record of how much is already in use.
2227 if (max_blocks
&& !sbinfo
->max_blocks
)
2229 if (max_inodes
&& !sbinfo
->max_inodes
)
2233 sbinfo
->max_blocks
= max_blocks
;
2234 sbinfo
->free_blocks
= max_blocks
- blocks
;
2235 sbinfo
->max_inodes
= max_inodes
;
2236 sbinfo
->free_inodes
= max_inodes
- inodes
;
2237 sbinfo
->policy
= policy
;
2238 sbinfo
->policy_nodes
= policy_nodes
;
2240 spin_unlock(&sbinfo
->stat_lock
);
2245 static void shmem_put_super(struct super_block
*sb
)
2247 kfree(sb
->s_fs_info
);
2248 sb
->s_fs_info
= NULL
;
2251 static int shmem_fill_super(struct super_block
*sb
,
2252 void *data
, int silent
)
2254 struct inode
*inode
;
2255 struct dentry
*root
;
2256 int mode
= S_IRWXUGO
| S_ISVTX
;
2257 uid_t uid
= current
->fsuid
;
2258 gid_t gid
= current
->fsgid
;
2260 struct shmem_sb_info
*sbinfo
;
2261 unsigned long blocks
= 0;
2262 unsigned long inodes
= 0;
2263 int policy
= MPOL_DEFAULT
;
2264 nodemask_t policy_nodes
= node_online_map
;
2268 * Per default we only allow half of the physical ram per
2269 * tmpfs instance, limiting inodes to one per page of lowmem;
2270 * but the internal instance is left unlimited.
2272 if (!(sb
->s_flags
& MS_NOUSER
)) {
2273 blocks
= totalram_pages
/ 2;
2274 inodes
= totalram_pages
- totalhigh_pages
;
2275 if (inodes
> blocks
)
2277 if (shmem_parse_options(data
, &mode
, &uid
, &gid
, &blocks
,
2278 &inodes
, &policy
, &policy_nodes
))
2281 sb
->s_export_op
= &shmem_export_ops
;
2283 sb
->s_flags
|= MS_NOUSER
;
2286 /* Round up to L1_CACHE_BYTES to resist false sharing */
2287 sbinfo
= kmalloc(max((int)sizeof(struct shmem_sb_info
),
2288 L1_CACHE_BYTES
), GFP_KERNEL
);
2292 spin_lock_init(&sbinfo
->stat_lock
);
2293 sbinfo
->max_blocks
= blocks
;
2294 sbinfo
->free_blocks
= blocks
;
2295 sbinfo
->max_inodes
= inodes
;
2296 sbinfo
->free_inodes
= inodes
;
2297 sbinfo
->policy
= policy
;
2298 sbinfo
->policy_nodes
= policy_nodes
;
2300 sb
->s_fs_info
= sbinfo
;
2301 sb
->s_maxbytes
= SHMEM_MAX_BYTES
;
2302 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2303 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2304 sb
->s_magic
= TMPFS_MAGIC
;
2305 sb
->s_op
= &shmem_ops
;
2306 sb
->s_time_gran
= 1;
2307 #ifdef CONFIG_TMPFS_POSIX_ACL
2308 sb
->s_xattr
= shmem_xattr_handlers
;
2309 sb
->s_flags
|= MS_POSIXACL
;
2312 inode
= shmem_get_inode(sb
, S_IFDIR
| mode
, 0);
2317 root
= d_alloc_root(inode
);
2326 shmem_put_super(sb
);
2330 static struct kmem_cache
*shmem_inode_cachep
;
2332 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2334 struct shmem_inode_info
*p
;
2335 p
= (struct shmem_inode_info
*)kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2338 return &p
->vfs_inode
;
2341 static void shmem_destroy_inode(struct inode
*inode
)
2343 if ((inode
->i_mode
& S_IFMT
) == S_IFREG
) {
2344 /* only struct inode is valid if it's an inline symlink */
2345 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2347 shmem_acl_destroy_inode(inode
);
2348 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2351 static void init_once(void *foo
, struct kmem_cache
*cachep
,
2352 unsigned long flags
)
2354 struct shmem_inode_info
*p
= (struct shmem_inode_info
*) foo
;
2356 inode_init_once(&p
->vfs_inode
);
2357 #ifdef CONFIG_TMPFS_POSIX_ACL
2359 p
->i_default_acl
= NULL
;
2363 static int init_inodecache(void)
2365 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2366 sizeof(struct shmem_inode_info
),
2367 0, 0, init_once
, NULL
);
2368 if (shmem_inode_cachep
== NULL
)
2373 static void destroy_inodecache(void)
2375 kmem_cache_destroy(shmem_inode_cachep
);
2378 static const struct address_space_operations shmem_aops
= {
2379 .writepage
= shmem_writepage
,
2380 .set_page_dirty
= __set_page_dirty_no_writeback
,
2382 .readpage
= shmem_readpage
,
2383 .prepare_write
= shmem_prepare_write
,
2384 .commit_write
= simple_commit_write
,
2386 .migratepage
= migrate_page
,
2389 static const struct file_operations shmem_file_operations
= {
2392 .llseek
= generic_file_llseek
,
2393 .read
= shmem_file_read
,
2394 .write
= shmem_file_write
,
2395 .fsync
= simple_sync_file
,
2396 .splice_read
= generic_file_splice_read
,
2397 .splice_write
= generic_file_splice_write
,
2401 static const struct inode_operations shmem_inode_operations
= {
2402 .truncate
= shmem_truncate
,
2403 .setattr
= shmem_notify_change
,
2404 .truncate_range
= shmem_truncate_range
,
2405 #ifdef CONFIG_TMPFS_POSIX_ACL
2406 .setxattr
= generic_setxattr
,
2407 .getxattr
= generic_getxattr
,
2408 .listxattr
= generic_listxattr
,
2409 .removexattr
= generic_removexattr
,
2410 .permission
= shmem_permission
,
2415 static const struct inode_operations shmem_dir_inode_operations
= {
2417 .create
= shmem_create
,
2418 .lookup
= simple_lookup
,
2420 .unlink
= shmem_unlink
,
2421 .symlink
= shmem_symlink
,
2422 .mkdir
= shmem_mkdir
,
2423 .rmdir
= shmem_rmdir
,
2424 .mknod
= shmem_mknod
,
2425 .rename
= shmem_rename
,
2427 #ifdef CONFIG_TMPFS_POSIX_ACL
2428 .setattr
= shmem_notify_change
,
2429 .setxattr
= generic_setxattr
,
2430 .getxattr
= generic_getxattr
,
2431 .listxattr
= generic_listxattr
,
2432 .removexattr
= generic_removexattr
,
2433 .permission
= shmem_permission
,
2437 static const struct inode_operations shmem_special_inode_operations
= {
2438 #ifdef CONFIG_TMPFS_POSIX_ACL
2439 .setattr
= shmem_notify_change
,
2440 .setxattr
= generic_setxattr
,
2441 .getxattr
= generic_getxattr
,
2442 .listxattr
= generic_listxattr
,
2443 .removexattr
= generic_removexattr
,
2444 .permission
= shmem_permission
,
2448 static const struct super_operations shmem_ops
= {
2449 .alloc_inode
= shmem_alloc_inode
,
2450 .destroy_inode
= shmem_destroy_inode
,
2452 .statfs
= shmem_statfs
,
2453 .remount_fs
= shmem_remount_fs
,
2455 .delete_inode
= shmem_delete_inode
,
2456 .drop_inode
= generic_delete_inode
,
2457 .put_super
= shmem_put_super
,
2460 static struct vm_operations_struct shmem_vm_ops
= {
2461 .nopage
= shmem_nopage
,
2462 .populate
= shmem_populate
,
2464 .set_policy
= shmem_set_policy
,
2465 .get_policy
= shmem_get_policy
,
2470 static int shmem_get_sb(struct file_system_type
*fs_type
,
2471 int flags
, const char *dev_name
, void *data
, struct vfsmount
*mnt
)
2473 return get_sb_nodev(fs_type
, flags
, data
, shmem_fill_super
, mnt
);
2476 static struct file_system_type tmpfs_fs_type
= {
2477 .owner
= THIS_MODULE
,
2479 .get_sb
= shmem_get_sb
,
2480 .kill_sb
= kill_litter_super
,
2482 static struct vfsmount
*shm_mnt
;
2484 static int __init
init_tmpfs(void)
2488 error
= init_inodecache();
2492 error
= register_filesystem(&tmpfs_fs_type
);
2494 printk(KERN_ERR
"Could not register tmpfs\n");
2498 shm_mnt
= vfs_kern_mount(&tmpfs_fs_type
, MS_NOUSER
,
2499 tmpfs_fs_type
.name
, NULL
);
2500 if (IS_ERR(shm_mnt
)) {
2501 error
= PTR_ERR(shm_mnt
);
2502 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2508 unregister_filesystem(&tmpfs_fs_type
);
2510 destroy_inodecache();
2512 shm_mnt
= ERR_PTR(error
);
2515 module_init(init_tmpfs
)
2518 * shmem_file_setup - get an unlinked file living in tmpfs
2520 * @name: name for dentry (to be seen in /proc/<pid>/maps
2521 * @size: size to be set for the file
2524 struct file
*shmem_file_setup(char *name
, loff_t size
, unsigned long flags
)
2528 struct inode
*inode
;
2529 struct dentry
*dentry
, *root
;
2532 if (IS_ERR(shm_mnt
))
2533 return (void *)shm_mnt
;
2535 if (size
< 0 || size
> SHMEM_MAX_BYTES
)
2536 return ERR_PTR(-EINVAL
);
2538 if (shmem_acct_size(flags
, size
))
2539 return ERR_PTR(-ENOMEM
);
2543 this.len
= strlen(name
);
2544 this.hash
= 0; /* will go */
2545 root
= shm_mnt
->mnt_root
;
2546 dentry
= d_alloc(root
, &this);
2551 file
= get_empty_filp();
2556 inode
= shmem_get_inode(root
->d_sb
, S_IFREG
| S_IRWXUGO
, 0);
2560 SHMEM_I(inode
)->flags
= flags
& VM_ACCOUNT
;
2561 d_instantiate(dentry
, inode
);
2562 inode
->i_size
= size
;
2563 inode
->i_nlink
= 0; /* It is unlinked */
2564 file
->f_path
.mnt
= mntget(shm_mnt
);
2565 file
->f_path
.dentry
= dentry
;
2566 file
->f_mapping
= inode
->i_mapping
;
2567 file
->f_op
= &shmem_file_operations
;
2568 file
->f_mode
= FMODE_WRITE
| FMODE_READ
;
2576 shmem_unacct_size(flags
, size
);
2577 return ERR_PTR(error
);
2581 * shmem_zero_setup - setup a shared anonymous mapping
2583 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2585 int shmem_zero_setup(struct vm_area_struct
*vma
)
2588 loff_t size
= vma
->vm_end
- vma
->vm_start
;
2590 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
2592 return PTR_ERR(file
);
2596 vma
->vm_file
= file
;
2597 vma
->vm_ops
= &shmem_vm_ops
;