2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 * This file is released under the GPL.
24 #include <linux/init.h>
25 #include <linux/vfs.h>
26 #include <linux/mount.h>
27 #include <linux/pagemap.h>
28 #include <linux/file.h>
30 #include <linux/module.h>
31 #include <linux/swap.h>
32 #include <linux/ima.h>
34 static struct vfsmount
*shm_mnt
;
38 * This virtual memory filesystem is heavily based on the ramfs. It
39 * extends ramfs by the ability to use swap and honor resource limits
40 * which makes it a completely usable filesystem.
43 #include <linux/xattr.h>
44 #include <linux/exportfs.h>
45 #include <linux/generic_acl.h>
46 #include <linux/mman.h>
47 #include <linux/string.h>
48 #include <linux/slab.h>
49 #include <linux/backing-dev.h>
50 #include <linux/shmem_fs.h>
51 #include <linux/writeback.h>
52 #include <linux/blkdev.h>
53 #include <linux/security.h>
54 #include <linux/swapops.h>
55 #include <linux/mempolicy.h>
56 #include <linux/namei.h>
57 #include <linux/ctype.h>
58 #include <linux/migrate.h>
59 #include <linux/highmem.h>
60 #include <linux/seq_file.h>
61 #include <linux/magic.h>
63 #include <asm/uaccess.h>
64 #include <asm/div64.h>
65 #include <asm/pgtable.h>
68 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
69 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
71 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
72 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
73 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
74 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
76 * We use / and * instead of shifts in the definitions below, so that the swap
77 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
79 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
80 #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
82 #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
83 #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
85 #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
86 #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
88 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
89 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
91 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
92 #define SHMEM_PAGEIN VM_READ
93 #define SHMEM_TRUNCATE VM_WRITE
95 /* Definition to limit shmem_truncate's steps between cond_rescheds */
96 #define LATENCY_LIMIT 64
98 /* Pretend that each entry is of this size in directory's i_size */
99 #define BOGO_DIRENT_SIZE 20
101 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
103 SGP_READ
, /* don't exceed i_size, don't allocate page */
104 SGP_CACHE
, /* don't exceed i_size, may allocate page */
105 SGP_DIRTY
, /* like SGP_CACHE, but set new page dirty */
106 SGP_WRITE
, /* may exceed i_size, may allocate page */
110 static unsigned long shmem_default_max_blocks(void)
112 return totalram_pages
/ 2;
115 static unsigned long shmem_default_max_inodes(void)
117 return min(totalram_pages
- totalhigh_pages
, totalram_pages
/ 2);
121 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
122 struct page
**pagep
, enum sgp_type sgp
, int *type
);
124 static inline struct page
*shmem_dir_alloc(gfp_t gfp_mask
)
127 * The above definition of ENTRIES_PER_PAGE, and the use of
128 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
129 * might be reconsidered if it ever diverges from PAGE_SIZE.
131 * Mobility flags are masked out as swap vectors cannot move
133 return alloc_pages((gfp_mask
& ~GFP_MOVABLE_MASK
) | __GFP_ZERO
,
134 PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
137 static inline void shmem_dir_free(struct page
*page
)
139 __free_pages(page
, PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
142 static struct page
**shmem_dir_map(struct page
*page
)
144 return (struct page
**)kmap_atomic(page
, KM_USER0
);
147 static inline void shmem_dir_unmap(struct page
**dir
)
149 kunmap_atomic(dir
, KM_USER0
);
152 static swp_entry_t
*shmem_swp_map(struct page
*page
)
154 return (swp_entry_t
*)kmap_atomic(page
, KM_USER1
);
157 static inline void shmem_swp_balance_unmap(void)
160 * When passing a pointer to an i_direct entry, to code which
161 * also handles indirect entries and so will shmem_swp_unmap,
162 * we must arrange for the preempt count to remain in balance.
163 * What kmap_atomic of a lowmem page does depends on config
164 * and architecture, so pretend to kmap_atomic some lowmem page.
166 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1
);
169 static inline void shmem_swp_unmap(swp_entry_t
*entry
)
171 kunmap_atomic(entry
, KM_USER1
);
174 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
176 return sb
->s_fs_info
;
180 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
181 * for shared memory and for shared anonymous (/dev/zero) mappings
182 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
183 * consistent with the pre-accounting of private mappings ...
185 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
187 return (flags
& VM_NORESERVE
) ?
188 0 : security_vm_enough_memory_kern(VM_ACCT(size
));
191 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
193 if (!(flags
& VM_NORESERVE
))
194 vm_unacct_memory(VM_ACCT(size
));
198 * ... whereas tmpfs objects are accounted incrementally as
199 * pages are allocated, in order to allow huge sparse files.
200 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
201 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
203 static inline int shmem_acct_block(unsigned long flags
)
205 return (flags
& VM_NORESERVE
) ?
206 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE
)) : 0;
209 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
211 if (flags
& VM_NORESERVE
)
212 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
215 static const struct super_operations shmem_ops
;
216 static const struct address_space_operations shmem_aops
;
217 static const struct file_operations shmem_file_operations
;
218 static const struct inode_operations shmem_inode_operations
;
219 static const struct inode_operations shmem_dir_inode_operations
;
220 static const struct inode_operations shmem_special_inode_operations
;
221 static struct vm_operations_struct shmem_vm_ops
;
223 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
224 .ra_pages
= 0, /* No readahead */
225 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
| BDI_CAP_SWAP_BACKED
,
226 .unplug_io_fn
= default_unplug_io_fn
,
229 static LIST_HEAD(shmem_swaplist
);
230 static DEFINE_MUTEX(shmem_swaplist_mutex
);
232 static void shmem_free_blocks(struct inode
*inode
, long pages
)
234 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
235 if (sbinfo
->max_blocks
) {
236 spin_lock(&sbinfo
->stat_lock
);
237 sbinfo
->free_blocks
+= pages
;
238 inode
->i_blocks
-= pages
*BLOCKS_PER_PAGE
;
239 spin_unlock(&sbinfo
->stat_lock
);
243 static int shmem_reserve_inode(struct super_block
*sb
)
245 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
246 if (sbinfo
->max_inodes
) {
247 spin_lock(&sbinfo
->stat_lock
);
248 if (!sbinfo
->free_inodes
) {
249 spin_unlock(&sbinfo
->stat_lock
);
252 sbinfo
->free_inodes
--;
253 spin_unlock(&sbinfo
->stat_lock
);
258 static void shmem_free_inode(struct super_block
*sb
)
260 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
261 if (sbinfo
->max_inodes
) {
262 spin_lock(&sbinfo
->stat_lock
);
263 sbinfo
->free_inodes
++;
264 spin_unlock(&sbinfo
->stat_lock
);
269 * shmem_recalc_inode - recalculate the size of an inode
270 * @inode: inode to recalc
272 * We have to calculate the free blocks since the mm can drop
273 * undirtied hole pages behind our back.
275 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
276 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
278 * It has to be called with the spinlock held.
280 static void shmem_recalc_inode(struct inode
*inode
)
282 struct shmem_inode_info
*info
= SHMEM_I(inode
);
285 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
287 info
->alloced
-= freed
;
288 shmem_unacct_blocks(info
->flags
, freed
);
289 shmem_free_blocks(inode
, freed
);
294 * shmem_swp_entry - find the swap vector position in the info structure
295 * @info: info structure for the inode
296 * @index: index of the page to find
297 * @page: optional page to add to the structure. Has to be preset to
300 * If there is no space allocated yet it will return NULL when
301 * page is NULL, else it will use the page for the needed block,
302 * setting it to NULL on return to indicate that it has been used.
304 * The swap vector is organized the following way:
306 * There are SHMEM_NR_DIRECT entries directly stored in the
307 * shmem_inode_info structure. So small files do not need an addional
310 * For pages with index > SHMEM_NR_DIRECT there is the pointer
311 * i_indirect which points to a page which holds in the first half
312 * doubly indirect blocks, in the second half triple indirect blocks:
314 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
315 * following layout (for SHMEM_NR_DIRECT == 16):
317 * i_indirect -> dir --> 16-19
330 static swp_entry_t
*shmem_swp_entry(struct shmem_inode_info
*info
, unsigned long index
, struct page
**page
)
332 unsigned long offset
;
336 if (index
< SHMEM_NR_DIRECT
) {
337 shmem_swp_balance_unmap();
338 return info
->i_direct
+index
;
340 if (!info
->i_indirect
) {
342 info
->i_indirect
= *page
;
345 return NULL
; /* need another page */
348 index
-= SHMEM_NR_DIRECT
;
349 offset
= index
% ENTRIES_PER_PAGE
;
350 index
/= ENTRIES_PER_PAGE
;
351 dir
= shmem_dir_map(info
->i_indirect
);
353 if (index
>= ENTRIES_PER_PAGE
/2) {
354 index
-= ENTRIES_PER_PAGE
/2;
355 dir
+= ENTRIES_PER_PAGE
/2 + index
/ENTRIES_PER_PAGE
;
356 index
%= ENTRIES_PER_PAGE
;
363 shmem_dir_unmap(dir
);
364 return NULL
; /* need another page */
366 shmem_dir_unmap(dir
);
367 dir
= shmem_dir_map(subdir
);
373 if (!page
|| !(subdir
= *page
)) {
374 shmem_dir_unmap(dir
);
375 return NULL
; /* need a page */
380 shmem_dir_unmap(dir
);
381 return shmem_swp_map(subdir
) + offset
;
384 static void shmem_swp_set(struct shmem_inode_info
*info
, swp_entry_t
*entry
, unsigned long value
)
386 long incdec
= value
? 1: -1;
389 info
->swapped
+= incdec
;
390 if ((unsigned long)(entry
- info
->i_direct
) >= SHMEM_NR_DIRECT
) {
391 struct page
*page
= kmap_atomic_to_page(entry
);
392 set_page_private(page
, page_private(page
) + incdec
);
397 * shmem_swp_alloc - get the position of the swap entry for the page.
398 * @info: info structure for the inode
399 * @index: index of the page to find
400 * @sgp: check and recheck i_size? skip allocation?
402 * If the entry does not exist, allocate it.
404 static swp_entry_t
*shmem_swp_alloc(struct shmem_inode_info
*info
, unsigned long index
, enum sgp_type sgp
)
406 struct inode
*inode
= &info
->vfs_inode
;
407 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
408 struct page
*page
= NULL
;
411 if (sgp
!= SGP_WRITE
&&
412 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
413 return ERR_PTR(-EINVAL
);
415 while (!(entry
= shmem_swp_entry(info
, index
, &page
))) {
417 return shmem_swp_map(ZERO_PAGE(0));
419 * Test free_blocks against 1 not 0, since we have 1 data
420 * page (and perhaps indirect index pages) yet to allocate:
421 * a waste to allocate index if we cannot allocate data.
423 if (sbinfo
->max_blocks
) {
424 spin_lock(&sbinfo
->stat_lock
);
425 if (sbinfo
->free_blocks
<= 1) {
426 spin_unlock(&sbinfo
->stat_lock
);
427 return ERR_PTR(-ENOSPC
);
429 sbinfo
->free_blocks
--;
430 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
431 spin_unlock(&sbinfo
->stat_lock
);
434 spin_unlock(&info
->lock
);
435 page
= shmem_dir_alloc(mapping_gfp_mask(inode
->i_mapping
));
437 set_page_private(page
, 0);
438 spin_lock(&info
->lock
);
441 shmem_free_blocks(inode
, 1);
442 return ERR_PTR(-ENOMEM
);
444 if (sgp
!= SGP_WRITE
&&
445 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
446 entry
= ERR_PTR(-EINVAL
);
449 if (info
->next_index
<= index
)
450 info
->next_index
= index
+ 1;
453 /* another task gave its page, or truncated the file */
454 shmem_free_blocks(inode
, 1);
455 shmem_dir_free(page
);
457 if (info
->next_index
<= index
&& !IS_ERR(entry
))
458 info
->next_index
= index
+ 1;
463 * shmem_free_swp - free some swap entries in a directory
464 * @dir: pointer to the directory
465 * @edir: pointer after last entry of the directory
466 * @punch_lock: pointer to spinlock when needed for the holepunch case
468 static int shmem_free_swp(swp_entry_t
*dir
, swp_entry_t
*edir
,
469 spinlock_t
*punch_lock
)
471 spinlock_t
*punch_unlock
= NULL
;
475 for (ptr
= dir
; ptr
< edir
; ptr
++) {
477 if (unlikely(punch_lock
)) {
478 punch_unlock
= punch_lock
;
480 spin_lock(punch_unlock
);
484 free_swap_and_cache(*ptr
);
485 *ptr
= (swp_entry_t
){0};
490 spin_unlock(punch_unlock
);
494 static int shmem_map_and_free_swp(struct page
*subdir
, int offset
,
495 int limit
, struct page
***dir
, spinlock_t
*punch_lock
)
500 ptr
= shmem_swp_map(subdir
);
501 for (; offset
< limit
; offset
+= LATENCY_LIMIT
) {
502 int size
= limit
- offset
;
503 if (size
> LATENCY_LIMIT
)
504 size
= LATENCY_LIMIT
;
505 freed
+= shmem_free_swp(ptr
+offset
, ptr
+offset
+size
,
507 if (need_resched()) {
508 shmem_swp_unmap(ptr
);
510 shmem_dir_unmap(*dir
);
514 ptr
= shmem_swp_map(subdir
);
517 shmem_swp_unmap(ptr
);
521 static void shmem_free_pages(struct list_head
*next
)
527 page
= container_of(next
, struct page
, lru
);
529 shmem_dir_free(page
);
531 if (freed
>= LATENCY_LIMIT
) {
538 static void shmem_truncate_range(struct inode
*inode
, loff_t start
, loff_t end
)
540 struct shmem_inode_info
*info
= SHMEM_I(inode
);
545 unsigned long diroff
;
551 LIST_HEAD(pages_to_free
);
552 long nr_pages_to_free
= 0;
553 long nr_swaps_freed
= 0;
557 spinlock_t
*needs_lock
;
558 spinlock_t
*punch_lock
;
559 unsigned long upper_limit
;
561 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
562 idx
= (start
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
563 if (idx
>= info
->next_index
)
566 spin_lock(&info
->lock
);
567 info
->flags
|= SHMEM_TRUNCATE
;
568 if (likely(end
== (loff_t
) -1)) {
569 limit
= info
->next_index
;
570 upper_limit
= SHMEM_MAX_INDEX
;
571 info
->next_index
= idx
;
575 if (end
+ 1 >= inode
->i_size
) { /* we may free a little more */
576 limit
= (inode
->i_size
+ PAGE_CACHE_SIZE
- 1) >>
578 upper_limit
= SHMEM_MAX_INDEX
;
580 limit
= (end
+ 1) >> PAGE_CACHE_SHIFT
;
583 needs_lock
= &info
->lock
;
587 topdir
= info
->i_indirect
;
588 if (topdir
&& idx
<= SHMEM_NR_DIRECT
&& !punch_hole
) {
589 info
->i_indirect
= NULL
;
591 list_add(&topdir
->lru
, &pages_to_free
);
593 spin_unlock(&info
->lock
);
595 if (info
->swapped
&& idx
< SHMEM_NR_DIRECT
) {
596 ptr
= info
->i_direct
;
598 if (size
> SHMEM_NR_DIRECT
)
599 size
= SHMEM_NR_DIRECT
;
600 nr_swaps_freed
= shmem_free_swp(ptr
+idx
, ptr
+size
, needs_lock
);
604 * If there are no indirect blocks or we are punching a hole
605 * below indirect blocks, nothing to be done.
607 if (!topdir
|| limit
<= SHMEM_NR_DIRECT
)
611 * The truncation case has already dropped info->lock, and we're safe
612 * because i_size and next_index have already been lowered, preventing
613 * access beyond. But in the punch_hole case, we still need to take
614 * the lock when updating the swap directory, because there might be
615 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
616 * shmem_writepage. However, whenever we find we can remove a whole
617 * directory page (not at the misaligned start or end of the range),
618 * we first NULLify its pointer in the level above, and then have no
619 * need to take the lock when updating its contents: needs_lock and
620 * punch_lock (either pointing to info->lock or NULL) manage this.
623 upper_limit
-= SHMEM_NR_DIRECT
;
624 limit
-= SHMEM_NR_DIRECT
;
625 idx
= (idx
> SHMEM_NR_DIRECT
)? (idx
- SHMEM_NR_DIRECT
): 0;
626 offset
= idx
% ENTRIES_PER_PAGE
;
629 dir
= shmem_dir_map(topdir
);
630 stage
= ENTRIES_PER_PAGEPAGE
/2;
631 if (idx
< ENTRIES_PER_PAGEPAGE
/2) {
633 diroff
= idx
/ENTRIES_PER_PAGE
;
635 dir
+= ENTRIES_PER_PAGE
/2;
636 dir
+= (idx
- ENTRIES_PER_PAGEPAGE
/2)/ENTRIES_PER_PAGEPAGE
;
638 stage
+= ENTRIES_PER_PAGEPAGE
;
641 diroff
= ((idx
- ENTRIES_PER_PAGEPAGE
/2) %
642 ENTRIES_PER_PAGEPAGE
) / ENTRIES_PER_PAGE
;
643 if (!diroff
&& !offset
&& upper_limit
>= stage
) {
645 spin_lock(needs_lock
);
647 spin_unlock(needs_lock
);
652 list_add(&middir
->lru
, &pages_to_free
);
654 shmem_dir_unmap(dir
);
655 dir
= shmem_dir_map(middir
);
663 for (; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, diroff
++) {
664 if (unlikely(idx
== stage
)) {
665 shmem_dir_unmap(dir
);
666 dir
= shmem_dir_map(topdir
) +
667 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
670 idx
+= ENTRIES_PER_PAGEPAGE
;
674 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
677 needs_lock
= &info
->lock
;
678 if (upper_limit
>= stage
) {
680 spin_lock(needs_lock
);
682 spin_unlock(needs_lock
);
687 list_add(&middir
->lru
, &pages_to_free
);
689 shmem_dir_unmap(dir
);
691 dir
= shmem_dir_map(middir
);
694 punch_lock
= needs_lock
;
695 subdir
= dir
[diroff
];
696 if (subdir
&& !offset
&& upper_limit
-idx
>= ENTRIES_PER_PAGE
) {
698 spin_lock(needs_lock
);
700 spin_unlock(needs_lock
);
705 list_add(&subdir
->lru
, &pages_to_free
);
707 if (subdir
&& page_private(subdir
) /* has swap entries */) {
709 if (size
> ENTRIES_PER_PAGE
)
710 size
= ENTRIES_PER_PAGE
;
711 freed
= shmem_map_and_free_swp(subdir
,
712 offset
, size
, &dir
, punch_lock
);
714 dir
= shmem_dir_map(middir
);
715 nr_swaps_freed
+= freed
;
716 if (offset
|| punch_lock
) {
717 spin_lock(&info
->lock
);
718 set_page_private(subdir
,
719 page_private(subdir
) - freed
);
720 spin_unlock(&info
->lock
);
722 BUG_ON(page_private(subdir
) != freed
);
727 shmem_dir_unmap(dir
);
729 if (inode
->i_mapping
->nrpages
&& (info
->flags
& SHMEM_PAGEIN
)) {
731 * Call truncate_inode_pages again: racing shmem_unuse_inode
732 * may have swizzled a page in from swap since vmtruncate or
733 * generic_delete_inode did it, before we lowered next_index.
734 * Also, though shmem_getpage checks i_size before adding to
735 * cache, no recheck after: so fix the narrow window there too.
737 * Recalling truncate_inode_pages_range and unmap_mapping_range
738 * every time for punch_hole (which never got a chance to clear
739 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
740 * yet hardly ever necessary: try to optimize them out later.
742 truncate_inode_pages_range(inode
->i_mapping
, start
, end
);
744 unmap_mapping_range(inode
->i_mapping
, start
,
748 spin_lock(&info
->lock
);
749 info
->flags
&= ~SHMEM_TRUNCATE
;
750 info
->swapped
-= nr_swaps_freed
;
751 if (nr_pages_to_free
)
752 shmem_free_blocks(inode
, nr_pages_to_free
);
753 shmem_recalc_inode(inode
);
754 spin_unlock(&info
->lock
);
757 * Empty swap vector directory pages to be freed?
759 if (!list_empty(&pages_to_free
)) {
760 pages_to_free
.prev
->next
= NULL
;
761 shmem_free_pages(pages_to_free
.next
);
765 static void shmem_truncate(struct inode
*inode
)
767 shmem_truncate_range(inode
, inode
->i_size
, (loff_t
)-1);
770 static int shmem_notify_change(struct dentry
*dentry
, struct iattr
*attr
)
772 struct inode
*inode
= dentry
->d_inode
;
773 struct page
*page
= NULL
;
776 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
777 if (attr
->ia_size
< inode
->i_size
) {
779 * If truncating down to a partial page, then
780 * if that page is already allocated, hold it
781 * in memory until the truncation is over, so
782 * truncate_partial_page cannnot miss it were
783 * it assigned to swap.
785 if (attr
->ia_size
& (PAGE_CACHE_SIZE
-1)) {
786 (void) shmem_getpage(inode
,
787 attr
->ia_size
>>PAGE_CACHE_SHIFT
,
788 &page
, SGP_READ
, NULL
);
793 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
794 * detect if any pages might have been added to cache
795 * after truncate_inode_pages. But we needn't bother
796 * if it's being fully truncated to zero-length: the
797 * nrpages check is efficient enough in that case.
800 struct shmem_inode_info
*info
= SHMEM_I(inode
);
801 spin_lock(&info
->lock
);
802 info
->flags
&= ~SHMEM_PAGEIN
;
803 spin_unlock(&info
->lock
);
808 error
= inode_change_ok(inode
, attr
);
810 error
= inode_setattr(inode
, attr
);
811 #ifdef CONFIG_TMPFS_POSIX_ACL
812 if (!error
&& (attr
->ia_valid
& ATTR_MODE
))
813 error
= generic_acl_chmod(inode
, &shmem_acl_ops
);
816 page_cache_release(page
);
820 static void shmem_delete_inode(struct inode
*inode
)
822 struct shmem_inode_info
*info
= SHMEM_I(inode
);
824 if (inode
->i_op
->truncate
== shmem_truncate
) {
825 truncate_inode_pages(inode
->i_mapping
, 0);
826 shmem_unacct_size(info
->flags
, inode
->i_size
);
828 shmem_truncate(inode
);
829 if (!list_empty(&info
->swaplist
)) {
830 mutex_lock(&shmem_swaplist_mutex
);
831 list_del_init(&info
->swaplist
);
832 mutex_unlock(&shmem_swaplist_mutex
);
835 BUG_ON(inode
->i_blocks
);
836 shmem_free_inode(inode
->i_sb
);
840 static inline int shmem_find_swp(swp_entry_t entry
, swp_entry_t
*dir
, swp_entry_t
*edir
)
844 for (ptr
= dir
; ptr
< edir
; ptr
++) {
845 if (ptr
->val
== entry
.val
)
851 static int shmem_unuse_inode(struct shmem_inode_info
*info
, swp_entry_t entry
, struct page
*page
)
865 ptr
= info
->i_direct
;
866 spin_lock(&info
->lock
);
867 if (!info
->swapped
) {
868 list_del_init(&info
->swaplist
);
871 limit
= info
->next_index
;
873 if (size
> SHMEM_NR_DIRECT
)
874 size
= SHMEM_NR_DIRECT
;
875 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
878 if (!info
->i_indirect
)
881 dir
= shmem_dir_map(info
->i_indirect
);
882 stage
= SHMEM_NR_DIRECT
+ ENTRIES_PER_PAGEPAGE
/2;
884 for (idx
= SHMEM_NR_DIRECT
; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, dir
++) {
885 if (unlikely(idx
== stage
)) {
886 shmem_dir_unmap(dir
-1);
887 if (cond_resched_lock(&info
->lock
)) {
888 /* check it has not been truncated */
889 if (limit
> info
->next_index
) {
890 limit
= info
->next_index
;
895 dir
= shmem_dir_map(info
->i_indirect
) +
896 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
899 idx
+= ENTRIES_PER_PAGEPAGE
;
903 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
905 shmem_dir_unmap(dir
);
906 dir
= shmem_dir_map(subdir
);
909 if (subdir
&& page_private(subdir
)) {
910 ptr
= shmem_swp_map(subdir
);
912 if (size
> ENTRIES_PER_PAGE
)
913 size
= ENTRIES_PER_PAGE
;
914 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
915 shmem_swp_unmap(ptr
);
917 shmem_dir_unmap(dir
);
923 shmem_dir_unmap(dir
-1);
925 spin_unlock(&info
->lock
);
929 inode
= igrab(&info
->vfs_inode
);
930 spin_unlock(&info
->lock
);
933 * Move _head_ to start search for next from here.
934 * But be careful: shmem_delete_inode checks list_empty without taking
935 * mutex, and there's an instant in list_move_tail when info->swaplist
936 * would appear empty, if it were the only one on shmem_swaplist. We
937 * could avoid doing it if inode NULL; or use this minor optimization.
939 if (shmem_swaplist
.next
!= &info
->swaplist
)
940 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
941 mutex_unlock(&shmem_swaplist_mutex
);
947 * Charge page using GFP_KERNEL while we can wait.
948 * Charged back to the user(not to caller) when swap account is used.
949 * add_to_page_cache() will be called with GFP_NOWAIT.
951 error
= mem_cgroup_cache_charge(page
, current
->mm
, GFP_KERNEL
);
954 error
= radix_tree_preload(GFP_KERNEL
);
956 mem_cgroup_uncharge_cache_page(page
);
961 spin_lock(&info
->lock
);
962 ptr
= shmem_swp_entry(info
, idx
, NULL
);
963 if (ptr
&& ptr
->val
== entry
.val
) {
964 error
= add_to_page_cache_locked(page
, inode
->i_mapping
,
966 /* does mem_cgroup_uncharge_cache_page on error */
967 } else /* we must compensate for our precharge above */
968 mem_cgroup_uncharge_cache_page(page
);
970 if (error
== -EEXIST
) {
971 struct page
*filepage
= find_get_page(inode
->i_mapping
, idx
);
975 * There might be a more uptodate page coming down
976 * from a stacked writepage: forget our swappage if so.
978 if (PageUptodate(filepage
))
980 page_cache_release(filepage
);
984 delete_from_swap_cache(page
);
985 set_page_dirty(page
);
986 info
->flags
|= SHMEM_PAGEIN
;
987 shmem_swp_set(info
, ptr
, 0);
989 error
= 1; /* not an error, but entry was found */
992 shmem_swp_unmap(ptr
);
993 spin_unlock(&info
->lock
);
994 radix_tree_preload_end();
997 page_cache_release(page
);
998 iput(inode
); /* allows for NULL */
1003 * shmem_unuse() search for an eventually swapped out shmem page.
1005 int shmem_unuse(swp_entry_t entry
, struct page
*page
)
1007 struct list_head
*p
, *next
;
1008 struct shmem_inode_info
*info
;
1011 mutex_lock(&shmem_swaplist_mutex
);
1012 list_for_each_safe(p
, next
, &shmem_swaplist
) {
1013 info
= list_entry(p
, struct shmem_inode_info
, swaplist
);
1014 found
= shmem_unuse_inode(info
, entry
, page
);
1019 mutex_unlock(&shmem_swaplist_mutex
);
1020 out
: return found
; /* 0 or 1 or -ENOMEM */
1024 * Move the page from the page cache to the swap cache.
1026 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
1028 struct shmem_inode_info
*info
;
1029 swp_entry_t
*entry
, swap
;
1030 struct address_space
*mapping
;
1031 unsigned long index
;
1032 struct inode
*inode
;
1034 BUG_ON(!PageLocked(page
));
1035 mapping
= page
->mapping
;
1036 index
= page
->index
;
1037 inode
= mapping
->host
;
1038 info
= SHMEM_I(inode
);
1039 if (info
->flags
& VM_LOCKED
)
1041 if (!total_swap_pages
)
1045 * shmem_backing_dev_info's capabilities prevent regular writeback or
1046 * sync from ever calling shmem_writepage; but a stacking filesystem
1047 * may use the ->writepage of its underlying filesystem, in which case
1048 * tmpfs should write out to swap only in response to memory pressure,
1049 * and not for pdflush or sync. However, in those cases, we do still
1050 * want to check if there's a redundant swappage to be discarded.
1052 if (wbc
->for_reclaim
)
1053 swap
= get_swap_page();
1057 spin_lock(&info
->lock
);
1058 if (index
>= info
->next_index
) {
1059 BUG_ON(!(info
->flags
& SHMEM_TRUNCATE
));
1062 entry
= shmem_swp_entry(info
, index
, NULL
);
1065 * The more uptodate page coming down from a stacked
1066 * writepage should replace our old swappage.
1068 free_swap_and_cache(*entry
);
1069 shmem_swp_set(info
, entry
, 0);
1071 shmem_recalc_inode(inode
);
1073 if (swap
.val
&& add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
1074 remove_from_page_cache(page
);
1075 shmem_swp_set(info
, entry
, swap
.val
);
1076 shmem_swp_unmap(entry
);
1077 if (list_empty(&info
->swaplist
))
1078 inode
= igrab(inode
);
1081 spin_unlock(&info
->lock
);
1082 swap_duplicate(swap
);
1083 BUG_ON(page_mapped(page
));
1084 page_cache_release(page
); /* pagecache ref */
1085 swap_writepage(page
, wbc
);
1087 mutex_lock(&shmem_swaplist_mutex
);
1088 /* move instead of add in case we're racing */
1089 list_move_tail(&info
->swaplist
, &shmem_swaplist
);
1090 mutex_unlock(&shmem_swaplist_mutex
);
1096 shmem_swp_unmap(entry
);
1098 spin_unlock(&info
->lock
);
1100 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1101 * clear SWAP_HAS_CACHE flag.
1103 swapcache_free(swap
, NULL
);
1105 set_page_dirty(page
);
1106 if (wbc
->for_reclaim
)
1107 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
1114 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
1118 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
1119 return; /* show nothing */
1121 mpol_to_str(buffer
, sizeof(buffer
), mpol
, 1);
1123 seq_printf(seq
, ",mpol=%s", buffer
);
1126 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
1128 struct mempolicy
*mpol
= NULL
;
1130 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
1131 mpol
= sbinfo
->mpol
;
1133 spin_unlock(&sbinfo
->stat_lock
);
1137 #endif /* CONFIG_TMPFS */
1139 static struct page
*shmem_swapin(swp_entry_t entry
, gfp_t gfp
,
1140 struct shmem_inode_info
*info
, unsigned long idx
)
1142 struct mempolicy mpol
, *spol
;
1143 struct vm_area_struct pvma
;
1146 spol
= mpol_cond_copy(&mpol
,
1147 mpol_shared_policy_lookup(&info
->policy
, idx
));
1149 /* Create a pseudo vma that just contains the policy */
1151 pvma
.vm_pgoff
= idx
;
1153 pvma
.vm_policy
= spol
;
1154 page
= swapin_readahead(entry
, gfp
, &pvma
, 0);
1158 static struct page
*shmem_alloc_page(gfp_t gfp
,
1159 struct shmem_inode_info
*info
, unsigned long idx
)
1161 struct vm_area_struct pvma
;
1163 /* Create a pseudo vma that just contains the policy */
1165 pvma
.vm_pgoff
= idx
;
1167 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, idx
);
1170 * alloc_page_vma() will drop the shared policy reference
1172 return alloc_page_vma(gfp
, &pvma
, 0);
1174 #else /* !CONFIG_NUMA */
1176 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*p
)
1179 #endif /* CONFIG_TMPFS */
1181 static inline struct page
*shmem_swapin(swp_entry_t entry
, gfp_t gfp
,
1182 struct shmem_inode_info
*info
, unsigned long idx
)
1184 return swapin_readahead(entry
, gfp
, NULL
, 0);
1187 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
1188 struct shmem_inode_info
*info
, unsigned long idx
)
1190 return alloc_page(gfp
);
1192 #endif /* CONFIG_NUMA */
1194 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1195 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
1202 * shmem_getpage - either get the page from swap or allocate a new one
1204 * If we allocate a new one we do not mark it dirty. That's up to the
1205 * vm. If we swap it in we mark it dirty since we also free the swap
1206 * entry since a page cannot live in both the swap and page cache
1208 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
1209 struct page
**pagep
, enum sgp_type sgp
, int *type
)
1211 struct address_space
*mapping
= inode
->i_mapping
;
1212 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1213 struct shmem_sb_info
*sbinfo
;
1214 struct page
*filepage
= *pagep
;
1215 struct page
*swappage
;
1221 if (idx
>= SHMEM_MAX_INDEX
)
1228 * Normally, filepage is NULL on entry, and either found
1229 * uptodate immediately, or allocated and zeroed, or read
1230 * in under swappage, which is then assigned to filepage.
1231 * But shmem_readpage (required for splice) passes in a locked
1232 * filepage, which may be found not uptodate by other callers
1233 * too, and may need to be copied from the swappage read in.
1237 filepage
= find_lock_page(mapping
, idx
);
1238 if (filepage
&& PageUptodate(filepage
))
1241 gfp
= mapping_gfp_mask(mapping
);
1244 * Try to preload while we can wait, to not make a habit of
1245 * draining atomic reserves; but don't latch on to this cpu.
1247 error
= radix_tree_preload(gfp
& ~__GFP_HIGHMEM
);
1250 radix_tree_preload_end();
1253 spin_lock(&info
->lock
);
1254 shmem_recalc_inode(inode
);
1255 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1256 if (IS_ERR(entry
)) {
1257 spin_unlock(&info
->lock
);
1258 error
= PTR_ERR(entry
);
1264 /* Look it up and read it in.. */
1265 swappage
= lookup_swap_cache(swap
);
1267 shmem_swp_unmap(entry
);
1268 /* here we actually do the io */
1269 if (type
&& !(*type
& VM_FAULT_MAJOR
)) {
1270 __count_vm_event(PGMAJFAULT
);
1271 *type
|= VM_FAULT_MAJOR
;
1273 spin_unlock(&info
->lock
);
1274 swappage
= shmem_swapin(swap
, gfp
, info
, idx
);
1276 spin_lock(&info
->lock
);
1277 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1279 error
= PTR_ERR(entry
);
1281 if (entry
->val
== swap
.val
)
1283 shmem_swp_unmap(entry
);
1285 spin_unlock(&info
->lock
);
1290 wait_on_page_locked(swappage
);
1291 page_cache_release(swappage
);
1295 /* We have to do this with page locked to prevent races */
1296 if (!trylock_page(swappage
)) {
1297 shmem_swp_unmap(entry
);
1298 spin_unlock(&info
->lock
);
1299 wait_on_page_locked(swappage
);
1300 page_cache_release(swappage
);
1303 if (PageWriteback(swappage
)) {
1304 shmem_swp_unmap(entry
);
1305 spin_unlock(&info
->lock
);
1306 wait_on_page_writeback(swappage
);
1307 unlock_page(swappage
);
1308 page_cache_release(swappage
);
1311 if (!PageUptodate(swappage
)) {
1312 shmem_swp_unmap(entry
);
1313 spin_unlock(&info
->lock
);
1314 unlock_page(swappage
);
1315 page_cache_release(swappage
);
1321 shmem_swp_set(info
, entry
, 0);
1322 shmem_swp_unmap(entry
);
1323 delete_from_swap_cache(swappage
);
1324 spin_unlock(&info
->lock
);
1325 copy_highpage(filepage
, swappage
);
1326 unlock_page(swappage
);
1327 page_cache_release(swappage
);
1328 flush_dcache_page(filepage
);
1329 SetPageUptodate(filepage
);
1330 set_page_dirty(filepage
);
1332 } else if (!(error
= add_to_page_cache_locked(swappage
, mapping
,
1333 idx
, GFP_NOWAIT
))) {
1334 info
->flags
|= SHMEM_PAGEIN
;
1335 shmem_swp_set(info
, entry
, 0);
1336 shmem_swp_unmap(entry
);
1337 delete_from_swap_cache(swappage
);
1338 spin_unlock(&info
->lock
);
1339 filepage
= swappage
;
1340 set_page_dirty(filepage
);
1343 shmem_swp_unmap(entry
);
1344 spin_unlock(&info
->lock
);
1345 if (error
== -ENOMEM
) {
1347 * reclaim from proper memory cgroup and
1348 * call memcg's OOM if needed.
1350 error
= mem_cgroup_shmem_charge_fallback(
1355 unlock_page(swappage
);
1356 page_cache_release(swappage
);
1360 unlock_page(swappage
);
1361 page_cache_release(swappage
);
1364 } else if (sgp
== SGP_READ
&& !filepage
) {
1365 shmem_swp_unmap(entry
);
1366 filepage
= find_get_page(mapping
, idx
);
1368 (!PageUptodate(filepage
) || !trylock_page(filepage
))) {
1369 spin_unlock(&info
->lock
);
1370 wait_on_page_locked(filepage
);
1371 page_cache_release(filepage
);
1375 spin_unlock(&info
->lock
);
1377 shmem_swp_unmap(entry
);
1378 sbinfo
= SHMEM_SB(inode
->i_sb
);
1379 if (sbinfo
->max_blocks
) {
1380 spin_lock(&sbinfo
->stat_lock
);
1381 if (sbinfo
->free_blocks
== 0 ||
1382 shmem_acct_block(info
->flags
)) {
1383 spin_unlock(&sbinfo
->stat_lock
);
1384 spin_unlock(&info
->lock
);
1388 sbinfo
->free_blocks
--;
1389 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1390 spin_unlock(&sbinfo
->stat_lock
);
1391 } else if (shmem_acct_block(info
->flags
)) {
1392 spin_unlock(&info
->lock
);
1400 spin_unlock(&info
->lock
);
1401 filepage
= shmem_alloc_page(gfp
, info
, idx
);
1403 shmem_unacct_blocks(info
->flags
, 1);
1404 shmem_free_blocks(inode
, 1);
1408 SetPageSwapBacked(filepage
);
1410 /* Precharge page while we can wait, compensate after */
1411 error
= mem_cgroup_cache_charge(filepage
, current
->mm
,
1414 page_cache_release(filepage
);
1415 shmem_unacct_blocks(info
->flags
, 1);
1416 shmem_free_blocks(inode
, 1);
1421 spin_lock(&info
->lock
);
1422 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1424 error
= PTR_ERR(entry
);
1427 shmem_swp_unmap(entry
);
1429 ret
= error
|| swap
.val
;
1431 mem_cgroup_uncharge_cache_page(filepage
);
1433 ret
= add_to_page_cache_lru(filepage
, mapping
,
1436 * At add_to_page_cache_lru() failure, uncharge will
1437 * be done automatically.
1440 spin_unlock(&info
->lock
);
1441 page_cache_release(filepage
);
1442 shmem_unacct_blocks(info
->flags
, 1);
1443 shmem_free_blocks(inode
, 1);
1449 info
->flags
|= SHMEM_PAGEIN
;
1453 spin_unlock(&info
->lock
);
1454 clear_highpage(filepage
);
1455 flush_dcache_page(filepage
);
1456 SetPageUptodate(filepage
);
1457 if (sgp
== SGP_DIRTY
)
1458 set_page_dirty(filepage
);
1465 if (*pagep
!= filepage
) {
1466 unlock_page(filepage
);
1467 page_cache_release(filepage
);
1472 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1474 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1478 if (((loff_t
)vmf
->pgoff
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
1479 return VM_FAULT_SIGBUS
;
1481 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1483 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1485 return ret
| VM_FAULT_LOCKED
;
1489 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*new)
1491 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1492 return mpol_set_shared_policy(&SHMEM_I(i
)->policy
, vma
, new);
1495 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1498 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1501 idx
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1502 return mpol_shared_policy_lookup(&SHMEM_I(i
)->policy
, idx
);
1506 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1508 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1509 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1510 int retval
= -ENOMEM
;
1512 spin_lock(&info
->lock
);
1513 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1514 if (!user_shm_lock(inode
->i_size
, user
))
1516 info
->flags
|= VM_LOCKED
;
1517 mapping_set_unevictable(file
->f_mapping
);
1519 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1520 user_shm_unlock(inode
->i_size
, user
);
1521 info
->flags
&= ~VM_LOCKED
;
1522 mapping_clear_unevictable(file
->f_mapping
);
1523 scan_mapping_unevictable_pages(file
->f_mapping
);
1528 spin_unlock(&info
->lock
);
1532 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1534 file_accessed(file
);
1535 vma
->vm_ops
= &shmem_vm_ops
;
1536 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1540 static struct inode
*shmem_get_inode(struct super_block
*sb
, int mode
,
1541 dev_t dev
, unsigned long flags
)
1543 struct inode
*inode
;
1544 struct shmem_inode_info
*info
;
1545 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1547 if (shmem_reserve_inode(sb
))
1550 inode
= new_inode(sb
);
1552 inode
->i_mode
= mode
;
1553 inode
->i_uid
= current_fsuid();
1554 inode
->i_gid
= current_fsgid();
1555 inode
->i_blocks
= 0;
1556 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1557 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1558 inode
->i_generation
= get_seconds();
1559 info
= SHMEM_I(inode
);
1560 memset(info
, 0, (char *)inode
- (char *)info
);
1561 spin_lock_init(&info
->lock
);
1562 info
->flags
= flags
& VM_NORESERVE
;
1563 INIT_LIST_HEAD(&info
->swaplist
);
1564 cache_no_acl(inode
);
1566 switch (mode
& S_IFMT
) {
1568 inode
->i_op
= &shmem_special_inode_operations
;
1569 init_special_inode(inode
, mode
, dev
);
1572 inode
->i_mapping
->a_ops
= &shmem_aops
;
1573 inode
->i_op
= &shmem_inode_operations
;
1574 inode
->i_fop
= &shmem_file_operations
;
1575 mpol_shared_policy_init(&info
->policy
,
1576 shmem_get_sbmpol(sbinfo
));
1580 /* Some things misbehave if size == 0 on a directory */
1581 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1582 inode
->i_op
= &shmem_dir_inode_operations
;
1583 inode
->i_fop
= &simple_dir_operations
;
1587 * Must not load anything in the rbtree,
1588 * mpol_free_shared_policy will not be called.
1590 mpol_shared_policy_init(&info
->policy
, NULL
);
1594 shmem_free_inode(sb
);
1599 static const struct inode_operations shmem_symlink_inode_operations
;
1600 static const struct inode_operations shmem_symlink_inline_operations
;
1603 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1604 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1605 * below the loop driver, in the generic fashion that many filesystems support.
1607 static int shmem_readpage(struct file
*file
, struct page
*page
)
1609 struct inode
*inode
= page
->mapping
->host
;
1610 int error
= shmem_getpage(inode
, page
->index
, &page
, SGP_CACHE
, NULL
);
1616 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1617 loff_t pos
, unsigned len
, unsigned flags
,
1618 struct page
**pagep
, void **fsdata
)
1620 struct inode
*inode
= mapping
->host
;
1621 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1623 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1627 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1628 loff_t pos
, unsigned len
, unsigned copied
,
1629 struct page
*page
, void *fsdata
)
1631 struct inode
*inode
= mapping
->host
;
1633 if (pos
+ copied
> inode
->i_size
)
1634 i_size_write(inode
, pos
+ copied
);
1637 set_page_dirty(page
);
1638 page_cache_release(page
);
1643 static void do_shmem_file_read(struct file
*filp
, loff_t
*ppos
, read_descriptor_t
*desc
, read_actor_t actor
)
1645 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
1646 struct address_space
*mapping
= inode
->i_mapping
;
1647 unsigned long index
, offset
;
1648 enum sgp_type sgp
= SGP_READ
;
1651 * Might this read be for a stacking filesystem? Then when reading
1652 * holes of a sparse file, we actually need to allocate those pages,
1653 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1655 if (segment_eq(get_fs(), KERNEL_DS
))
1658 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1659 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1662 struct page
*page
= NULL
;
1663 unsigned long end_index
, nr
, ret
;
1664 loff_t i_size
= i_size_read(inode
);
1666 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1667 if (index
> end_index
)
1669 if (index
== end_index
) {
1670 nr
= i_size
& ~PAGE_CACHE_MASK
;
1675 desc
->error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1677 if (desc
->error
== -EINVAL
)
1685 * We must evaluate after, since reads (unlike writes)
1686 * are called without i_mutex protection against truncate
1688 nr
= PAGE_CACHE_SIZE
;
1689 i_size
= i_size_read(inode
);
1690 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1691 if (index
== end_index
) {
1692 nr
= i_size
& ~PAGE_CACHE_MASK
;
1695 page_cache_release(page
);
1703 * If users can be writing to this page using arbitrary
1704 * virtual addresses, take care about potential aliasing
1705 * before reading the page on the kernel side.
1707 if (mapping_writably_mapped(mapping
))
1708 flush_dcache_page(page
);
1710 * Mark the page accessed if we read the beginning.
1713 mark_page_accessed(page
);
1715 page
= ZERO_PAGE(0);
1716 page_cache_get(page
);
1720 * Ok, we have the page, and it's up-to-date, so
1721 * now we can copy it to user space...
1723 * The actor routine returns how many bytes were actually used..
1724 * NOTE! This may not be the same as how much of a user buffer
1725 * we filled up (we may be padding etc), so we can only update
1726 * "pos" here (the actor routine has to update the user buffer
1727 * pointers and the remaining count).
1729 ret
= actor(desc
, page
, offset
, nr
);
1731 index
+= offset
>> PAGE_CACHE_SHIFT
;
1732 offset
&= ~PAGE_CACHE_MASK
;
1734 page_cache_release(page
);
1735 if (ret
!= nr
|| !desc
->count
)
1741 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1742 file_accessed(filp
);
1745 static ssize_t
shmem_file_aio_read(struct kiocb
*iocb
,
1746 const struct iovec
*iov
, unsigned long nr_segs
, loff_t pos
)
1748 struct file
*filp
= iocb
->ki_filp
;
1752 loff_t
*ppos
= &iocb
->ki_pos
;
1754 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1758 for (seg
= 0; seg
< nr_segs
; seg
++) {
1759 read_descriptor_t desc
;
1762 desc
.arg
.buf
= iov
[seg
].iov_base
;
1763 desc
.count
= iov
[seg
].iov_len
;
1764 if (desc
.count
== 0)
1767 do_shmem_file_read(filp
, ppos
, &desc
, file_read_actor
);
1768 retval
+= desc
.written
;
1770 retval
= retval
?: desc
.error
;
1779 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1781 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1783 buf
->f_type
= TMPFS_MAGIC
;
1784 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1785 buf
->f_namelen
= NAME_MAX
;
1786 spin_lock(&sbinfo
->stat_lock
);
1787 if (sbinfo
->max_blocks
) {
1788 buf
->f_blocks
= sbinfo
->max_blocks
;
1789 buf
->f_bavail
= buf
->f_bfree
= sbinfo
->free_blocks
;
1791 if (sbinfo
->max_inodes
) {
1792 buf
->f_files
= sbinfo
->max_inodes
;
1793 buf
->f_ffree
= sbinfo
->free_inodes
;
1795 /* else leave those fields 0 like simple_statfs */
1796 spin_unlock(&sbinfo
->stat_lock
);
1801 * File creation. Allocate an inode, and we're done..
1804 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1806 struct inode
*inode
;
1807 int error
= -ENOSPC
;
1809 inode
= shmem_get_inode(dir
->i_sb
, mode
, dev
, VM_NORESERVE
);
1811 error
= security_inode_init_security(inode
, dir
, NULL
, NULL
,
1814 if (error
!= -EOPNOTSUPP
) {
1819 error
= shmem_acl_init(inode
, dir
);
1824 if (dir
->i_mode
& S_ISGID
) {
1825 inode
->i_gid
= dir
->i_gid
;
1827 inode
->i_mode
|= S_ISGID
;
1829 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1830 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1831 d_instantiate(dentry
, inode
);
1832 dget(dentry
); /* Extra count - pin the dentry in core */
1837 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1841 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1847 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1848 struct nameidata
*nd
)
1850 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
1856 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
1858 struct inode
*inode
= old_dentry
->d_inode
;
1862 * No ordinary (disk based) filesystem counts links as inodes;
1863 * but each new link needs a new dentry, pinning lowmem, and
1864 * tmpfs dentries cannot be pruned until they are unlinked.
1866 ret
= shmem_reserve_inode(inode
->i_sb
);
1870 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1871 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1873 atomic_inc(&inode
->i_count
); /* New dentry reference */
1874 dget(dentry
); /* Extra pinning count for the created dentry */
1875 d_instantiate(dentry
, inode
);
1880 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
1882 struct inode
*inode
= dentry
->d_inode
;
1884 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
1885 shmem_free_inode(inode
->i_sb
);
1887 dir
->i_size
-= BOGO_DIRENT_SIZE
;
1888 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1890 dput(dentry
); /* Undo the count from "create" - this does all the work */
1894 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1896 if (!simple_empty(dentry
))
1899 drop_nlink(dentry
->d_inode
);
1901 return shmem_unlink(dir
, dentry
);
1905 * The VFS layer already does all the dentry stuff for rename,
1906 * we just have to decrement the usage count for the target if
1907 * it exists so that the VFS layer correctly free's it when it
1910 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
1912 struct inode
*inode
= old_dentry
->d_inode
;
1913 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
1915 if (!simple_empty(new_dentry
))
1918 if (new_dentry
->d_inode
) {
1919 (void) shmem_unlink(new_dir
, new_dentry
);
1921 drop_nlink(old_dir
);
1922 } else if (they_are_dirs
) {
1923 drop_nlink(old_dir
);
1927 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
1928 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
1929 old_dir
->i_ctime
= old_dir
->i_mtime
=
1930 new_dir
->i_ctime
= new_dir
->i_mtime
=
1931 inode
->i_ctime
= CURRENT_TIME
;
1935 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
1939 struct inode
*inode
;
1940 struct page
*page
= NULL
;
1942 struct shmem_inode_info
*info
;
1944 len
= strlen(symname
) + 1;
1945 if (len
> PAGE_CACHE_SIZE
)
1946 return -ENAMETOOLONG
;
1948 inode
= shmem_get_inode(dir
->i_sb
, S_IFLNK
|S_IRWXUGO
, 0, VM_NORESERVE
);
1952 error
= security_inode_init_security(inode
, dir
, NULL
, NULL
,
1955 if (error
!= -EOPNOTSUPP
) {
1962 info
= SHMEM_I(inode
);
1963 inode
->i_size
= len
-1;
1964 if (len
<= (char *)inode
- (char *)info
) {
1966 memcpy(info
, symname
, len
);
1967 inode
->i_op
= &shmem_symlink_inline_operations
;
1969 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
1975 inode
->i_mapping
->a_ops
= &shmem_aops
;
1976 inode
->i_op
= &shmem_symlink_inode_operations
;
1977 kaddr
= kmap_atomic(page
, KM_USER0
);
1978 memcpy(kaddr
, symname
, len
);
1979 kunmap_atomic(kaddr
, KM_USER0
);
1980 set_page_dirty(page
);
1981 page_cache_release(page
);
1983 if (dir
->i_mode
& S_ISGID
)
1984 inode
->i_gid
= dir
->i_gid
;
1985 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1986 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1987 d_instantiate(dentry
, inode
);
1992 static void *shmem_follow_link_inline(struct dentry
*dentry
, struct nameidata
*nd
)
1994 nd_set_link(nd
, (char *)SHMEM_I(dentry
->d_inode
));
1998 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
2000 struct page
*page
= NULL
;
2001 int res
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
2002 nd_set_link(nd
, res
? ERR_PTR(res
) : kmap(page
));
2008 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2010 if (!IS_ERR(nd_get_link(nd
))) {
2011 struct page
*page
= cookie
;
2013 mark_page_accessed(page
);
2014 page_cache_release(page
);
2018 static const struct inode_operations shmem_symlink_inline_operations
= {
2019 .readlink
= generic_readlink
,
2020 .follow_link
= shmem_follow_link_inline
,
2023 static const struct inode_operations shmem_symlink_inode_operations
= {
2024 .truncate
= shmem_truncate
,
2025 .readlink
= generic_readlink
,
2026 .follow_link
= shmem_follow_link
,
2027 .put_link
= shmem_put_link
,
2030 #ifdef CONFIG_TMPFS_POSIX_ACL
2032 * Superblocks without xattr inode operations will get security.* xattr
2033 * support from the VFS "for free". As soon as we have any other xattrs
2034 * like ACLs, we also need to implement the security.* handlers at
2035 * filesystem level, though.
2038 static size_t shmem_xattr_security_list(struct inode
*inode
, char *list
,
2039 size_t list_len
, const char *name
,
2042 return security_inode_listsecurity(inode
, list
, list_len
);
2045 static int shmem_xattr_security_get(struct inode
*inode
, const char *name
,
2046 void *buffer
, size_t size
)
2048 if (strcmp(name
, "") == 0)
2050 return xattr_getsecurity(inode
, name
, buffer
, size
);
2053 static int shmem_xattr_security_set(struct inode
*inode
, const char *name
,
2054 const void *value
, size_t size
, int flags
)
2056 if (strcmp(name
, "") == 0)
2058 return security_inode_setsecurity(inode
, name
, value
, size
, flags
);
2061 static struct xattr_handler shmem_xattr_security_handler
= {
2062 .prefix
= XATTR_SECURITY_PREFIX
,
2063 .list
= shmem_xattr_security_list
,
2064 .get
= shmem_xattr_security_get
,
2065 .set
= shmem_xattr_security_set
,
2068 static struct xattr_handler
*shmem_xattr_handlers
[] = {
2069 &shmem_xattr_acl_access_handler
,
2070 &shmem_xattr_acl_default_handler
,
2071 &shmem_xattr_security_handler
,
2076 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2078 return ERR_PTR(-ESTALE
);
2081 static int shmem_match(struct inode
*ino
, void *vfh
)
2085 inum
= (inum
<< 32) | fh
[1];
2086 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2089 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
2090 struct fid
*fid
, int fh_len
, int fh_type
)
2092 struct inode
*inode
;
2093 struct dentry
*dentry
= NULL
;
2094 u64 inum
= fid
->raw
[2];
2095 inum
= (inum
<< 32) | fid
->raw
[1];
2100 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
2101 shmem_match
, fid
->raw
);
2103 dentry
= d_find_alias(inode
);
2110 static int shmem_encode_fh(struct dentry
*dentry
, __u32
*fh
, int *len
,
2113 struct inode
*inode
= dentry
->d_inode
;
2118 if (hlist_unhashed(&inode
->i_hash
)) {
2119 /* Unfortunately insert_inode_hash is not idempotent,
2120 * so as we hash inodes here rather than at creation
2121 * time, we need a lock to ensure we only try
2124 static DEFINE_SPINLOCK(lock
);
2126 if (hlist_unhashed(&inode
->i_hash
))
2127 __insert_inode_hash(inode
,
2128 inode
->i_ino
+ inode
->i_generation
);
2132 fh
[0] = inode
->i_generation
;
2133 fh
[1] = inode
->i_ino
;
2134 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2140 static const struct export_operations shmem_export_ops
= {
2141 .get_parent
= shmem_get_parent
,
2142 .encode_fh
= shmem_encode_fh
,
2143 .fh_to_dentry
= shmem_fh_to_dentry
,
2146 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2149 char *this_char
, *value
, *rest
;
2151 while (options
!= NULL
) {
2152 this_char
= options
;
2155 * NUL-terminate this option: unfortunately,
2156 * mount options form a comma-separated list,
2157 * but mpol's nodelist may also contain commas.
2159 options
= strchr(options
, ',');
2160 if (options
== NULL
)
2163 if (!isdigit(*options
)) {
2170 if ((value
= strchr(this_char
,'=')) != NULL
) {
2174 "tmpfs: No value for mount option '%s'\n",
2179 if (!strcmp(this_char
,"size")) {
2180 unsigned long long size
;
2181 size
= memparse(value
,&rest
);
2183 size
<<= PAGE_SHIFT
;
2184 size
*= totalram_pages
;
2190 sbinfo
->max_blocks
=
2191 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2192 } else if (!strcmp(this_char
,"nr_blocks")) {
2193 sbinfo
->max_blocks
= memparse(value
, &rest
);
2196 } else if (!strcmp(this_char
,"nr_inodes")) {
2197 sbinfo
->max_inodes
= memparse(value
, &rest
);
2200 } else if (!strcmp(this_char
,"mode")) {
2203 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2206 } else if (!strcmp(this_char
,"uid")) {
2209 sbinfo
->uid
= simple_strtoul(value
, &rest
, 0);
2212 } else if (!strcmp(this_char
,"gid")) {
2215 sbinfo
->gid
= simple_strtoul(value
, &rest
, 0);
2218 } else if (!strcmp(this_char
,"mpol")) {
2219 if (mpol_parse_str(value
, &sbinfo
->mpol
, 1))
2222 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2230 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2236 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2238 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2239 struct shmem_sb_info config
= *sbinfo
;
2240 unsigned long blocks
;
2241 unsigned long inodes
;
2242 int error
= -EINVAL
;
2244 if (shmem_parse_options(data
, &config
, true))
2247 spin_lock(&sbinfo
->stat_lock
);
2248 blocks
= sbinfo
->max_blocks
- sbinfo
->free_blocks
;
2249 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2250 if (config
.max_blocks
< blocks
)
2252 if (config
.max_inodes
< inodes
)
2255 * Those tests also disallow limited->unlimited while any are in
2256 * use, so i_blocks will always be zero when max_blocks is zero;
2257 * but we must separately disallow unlimited->limited, because
2258 * in that case we have no record of how much is already in use.
2260 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2262 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2266 sbinfo
->max_blocks
= config
.max_blocks
;
2267 sbinfo
->free_blocks
= config
.max_blocks
- blocks
;
2268 sbinfo
->max_inodes
= config
.max_inodes
;
2269 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2271 mpol_put(sbinfo
->mpol
);
2272 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2274 spin_unlock(&sbinfo
->stat_lock
);
2278 static int shmem_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
2280 struct shmem_sb_info
*sbinfo
= SHMEM_SB(vfs
->mnt_sb
);
2282 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2283 seq_printf(seq
, ",size=%luk",
2284 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2285 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2286 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2287 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2288 seq_printf(seq
, ",mode=%03o", sbinfo
->mode
);
2289 if (sbinfo
->uid
!= 0)
2290 seq_printf(seq
, ",uid=%u", sbinfo
->uid
);
2291 if (sbinfo
->gid
!= 0)
2292 seq_printf(seq
, ",gid=%u", sbinfo
->gid
);
2293 shmem_show_mpol(seq
, sbinfo
->mpol
);
2296 #endif /* CONFIG_TMPFS */
2298 static void shmem_put_super(struct super_block
*sb
)
2300 kfree(sb
->s_fs_info
);
2301 sb
->s_fs_info
= NULL
;
2304 int shmem_fill_super(struct super_block
*sb
, void *data
, int silent
)
2306 struct inode
*inode
;
2307 struct dentry
*root
;
2308 struct shmem_sb_info
*sbinfo
;
2311 /* Round up to L1_CACHE_BYTES to resist false sharing */
2312 sbinfo
= kzalloc(max((int)sizeof(struct shmem_sb_info
),
2313 L1_CACHE_BYTES
), GFP_KERNEL
);
2317 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2318 sbinfo
->uid
= current_fsuid();
2319 sbinfo
->gid
= current_fsgid();
2320 sb
->s_fs_info
= sbinfo
;
2324 * Per default we only allow half of the physical ram per
2325 * tmpfs instance, limiting inodes to one per page of lowmem;
2326 * but the internal instance is left unlimited.
2328 if (!(sb
->s_flags
& MS_NOUSER
)) {
2329 sbinfo
->max_blocks
= shmem_default_max_blocks();
2330 sbinfo
->max_inodes
= shmem_default_max_inodes();
2331 if (shmem_parse_options(data
, sbinfo
, false)) {
2336 sb
->s_export_op
= &shmem_export_ops
;
2338 sb
->s_flags
|= MS_NOUSER
;
2341 spin_lock_init(&sbinfo
->stat_lock
);
2342 sbinfo
->free_blocks
= sbinfo
->max_blocks
;
2343 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2345 sb
->s_maxbytes
= SHMEM_MAX_BYTES
;
2346 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2347 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2348 sb
->s_magic
= TMPFS_MAGIC
;
2349 sb
->s_op
= &shmem_ops
;
2350 sb
->s_time_gran
= 1;
2351 #ifdef CONFIG_TMPFS_POSIX_ACL
2352 sb
->s_xattr
= shmem_xattr_handlers
;
2353 sb
->s_flags
|= MS_POSIXACL
;
2356 inode
= shmem_get_inode(sb
, S_IFDIR
| sbinfo
->mode
, 0, VM_NORESERVE
);
2359 inode
->i_uid
= sbinfo
->uid
;
2360 inode
->i_gid
= sbinfo
->gid
;
2361 root
= d_alloc_root(inode
);
2370 shmem_put_super(sb
);
2374 static struct kmem_cache
*shmem_inode_cachep
;
2376 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2378 struct shmem_inode_info
*p
;
2379 p
= (struct shmem_inode_info
*)kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2382 return &p
->vfs_inode
;
2385 static void shmem_destroy_inode(struct inode
*inode
)
2387 if ((inode
->i_mode
& S_IFMT
) == S_IFREG
) {
2388 /* only struct inode is valid if it's an inline symlink */
2389 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2391 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2394 static void init_once(void *foo
)
2396 struct shmem_inode_info
*p
= (struct shmem_inode_info
*) foo
;
2398 inode_init_once(&p
->vfs_inode
);
2401 static int init_inodecache(void)
2403 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2404 sizeof(struct shmem_inode_info
),
2405 0, SLAB_PANIC
, init_once
);
2409 static void destroy_inodecache(void)
2411 kmem_cache_destroy(shmem_inode_cachep
);
2414 static const struct address_space_operations shmem_aops
= {
2415 .writepage
= shmem_writepage
,
2416 .set_page_dirty
= __set_page_dirty_no_writeback
,
2418 .readpage
= shmem_readpage
,
2419 .write_begin
= shmem_write_begin
,
2420 .write_end
= shmem_write_end
,
2422 .migratepage
= migrate_page
,
2425 static const struct file_operations shmem_file_operations
= {
2428 .llseek
= generic_file_llseek
,
2429 .read
= do_sync_read
,
2430 .write
= do_sync_write
,
2431 .aio_read
= shmem_file_aio_read
,
2432 .aio_write
= generic_file_aio_write
,
2433 .fsync
= simple_sync_file
,
2434 .splice_read
= generic_file_splice_read
,
2435 .splice_write
= generic_file_splice_write
,
2439 static const struct inode_operations shmem_inode_operations
= {
2440 .truncate
= shmem_truncate
,
2441 .setattr
= shmem_notify_change
,
2442 .truncate_range
= shmem_truncate_range
,
2443 #ifdef CONFIG_TMPFS_POSIX_ACL
2444 .setxattr
= generic_setxattr
,
2445 .getxattr
= generic_getxattr
,
2446 .listxattr
= generic_listxattr
,
2447 .removexattr
= generic_removexattr
,
2448 .check_acl
= shmem_check_acl
,
2453 static const struct inode_operations shmem_dir_inode_operations
= {
2455 .create
= shmem_create
,
2456 .lookup
= simple_lookup
,
2458 .unlink
= shmem_unlink
,
2459 .symlink
= shmem_symlink
,
2460 .mkdir
= shmem_mkdir
,
2461 .rmdir
= shmem_rmdir
,
2462 .mknod
= shmem_mknod
,
2463 .rename
= shmem_rename
,
2465 #ifdef CONFIG_TMPFS_POSIX_ACL
2466 .setattr
= shmem_notify_change
,
2467 .setxattr
= generic_setxattr
,
2468 .getxattr
= generic_getxattr
,
2469 .listxattr
= generic_listxattr
,
2470 .removexattr
= generic_removexattr
,
2471 .check_acl
= shmem_check_acl
,
2475 static const struct inode_operations shmem_special_inode_operations
= {
2476 #ifdef CONFIG_TMPFS_POSIX_ACL
2477 .setattr
= shmem_notify_change
,
2478 .setxattr
= generic_setxattr
,
2479 .getxattr
= generic_getxattr
,
2480 .listxattr
= generic_listxattr
,
2481 .removexattr
= generic_removexattr
,
2482 .check_acl
= shmem_check_acl
,
2486 static const struct super_operations shmem_ops
= {
2487 .alloc_inode
= shmem_alloc_inode
,
2488 .destroy_inode
= shmem_destroy_inode
,
2490 .statfs
= shmem_statfs
,
2491 .remount_fs
= shmem_remount_fs
,
2492 .show_options
= shmem_show_options
,
2494 .delete_inode
= shmem_delete_inode
,
2495 .drop_inode
= generic_delete_inode
,
2496 .put_super
= shmem_put_super
,
2499 static struct vm_operations_struct shmem_vm_ops
= {
2500 .fault
= shmem_fault
,
2502 .set_policy
= shmem_set_policy
,
2503 .get_policy
= shmem_get_policy
,
2508 static int shmem_get_sb(struct file_system_type
*fs_type
,
2509 int flags
, const char *dev_name
, void *data
, struct vfsmount
*mnt
)
2511 return get_sb_nodev(fs_type
, flags
, data
, shmem_fill_super
, mnt
);
2514 static struct file_system_type tmpfs_fs_type
= {
2515 .owner
= THIS_MODULE
,
2517 .get_sb
= shmem_get_sb
,
2518 .kill_sb
= kill_litter_super
,
2521 int __init
init_tmpfs(void)
2525 error
= bdi_init(&shmem_backing_dev_info
);
2529 error
= init_inodecache();
2533 error
= register_filesystem(&tmpfs_fs_type
);
2535 printk(KERN_ERR
"Could not register tmpfs\n");
2539 shm_mnt
= vfs_kern_mount(&tmpfs_fs_type
, MS_NOUSER
,
2540 tmpfs_fs_type
.name
, NULL
);
2541 if (IS_ERR(shm_mnt
)) {
2542 error
= PTR_ERR(shm_mnt
);
2543 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2549 unregister_filesystem(&tmpfs_fs_type
);
2551 destroy_inodecache();
2553 bdi_destroy(&shmem_backing_dev_info
);
2555 shm_mnt
= ERR_PTR(error
);
2559 #else /* !CONFIG_SHMEM */
2562 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2564 * This is intended for small system where the benefits of the full
2565 * shmem code (swap-backed and resource-limited) are outweighed by
2566 * their complexity. On systems without swap this code should be
2567 * effectively equivalent, but much lighter weight.
2570 #include <linux/ramfs.h>
2572 static struct file_system_type tmpfs_fs_type
= {
2574 .get_sb
= ramfs_get_sb
,
2575 .kill_sb
= kill_litter_super
,
2578 int __init
init_tmpfs(void)
2580 BUG_ON(register_filesystem(&tmpfs_fs_type
) != 0);
2582 shm_mnt
= kern_mount(&tmpfs_fs_type
);
2583 BUG_ON(IS_ERR(shm_mnt
));
2588 int shmem_unuse(swp_entry_t entry
, struct page
*page
)
2593 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
2598 #define shmem_vm_ops generic_file_vm_ops
2599 #define shmem_file_operations ramfs_file_operations
2600 #define shmem_get_inode(sb, mode, dev, flags) ramfs_get_inode(sb, mode, dev)
2601 #define shmem_acct_size(flags, size) 0
2602 #define shmem_unacct_size(flags, size) do {} while (0)
2603 #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
2605 #endif /* CONFIG_SHMEM */
2610 * shmem_file_setup - get an unlinked file living in tmpfs
2611 * @name: name for dentry (to be seen in /proc/<pid>/maps
2612 * @size: size to be set for the file
2613 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2615 struct file
*shmem_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2619 struct inode
*inode
;
2620 struct dentry
*dentry
, *root
;
2623 if (IS_ERR(shm_mnt
))
2624 return (void *)shm_mnt
;
2626 if (size
< 0 || size
> SHMEM_MAX_BYTES
)
2627 return ERR_PTR(-EINVAL
);
2629 if (shmem_acct_size(flags
, size
))
2630 return ERR_PTR(-ENOMEM
);
2634 this.len
= strlen(name
);
2635 this.hash
= 0; /* will go */
2636 root
= shm_mnt
->mnt_root
;
2637 dentry
= d_alloc(root
, &this);
2642 file
= get_empty_filp();
2647 inode
= shmem_get_inode(root
->d_sb
, S_IFREG
| S_IRWXUGO
, 0, flags
);
2651 d_instantiate(dentry
, inode
);
2652 inode
->i_size
= size
;
2653 inode
->i_nlink
= 0; /* It is unlinked */
2654 init_file(file
, shm_mnt
, dentry
, FMODE_WRITE
| FMODE_READ
,
2655 &shmem_file_operations
);
2658 error
= ramfs_nommu_expand_for_mapping(inode
, size
);
2662 ima_counts_get(file
);
2670 shmem_unacct_size(flags
, size
);
2671 return ERR_PTR(error
);
2673 EXPORT_SYMBOL_GPL(shmem_file_setup
);
2676 * shmem_zero_setup - setup a shared anonymous mapping
2677 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2679 int shmem_zero_setup(struct vm_area_struct
*vma
)
2682 loff_t size
= vma
->vm_end
- vma
->vm_start
;
2684 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
2686 return PTR_ERR(file
);
2690 vma
->vm_file
= file
;
2691 vma
->vm_ops
= &shmem_vm_ops
;