2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
17 * This file is released under the GPL.
21 * This virtual memory filesystem is heavily based on the ramfs. It
22 * extends ramfs by the ability to use swap and honor resource limits
23 * which makes it a completely usable filesystem.
26 #include <linux/module.h>
27 #include <linux/init.h>
29 #include <linux/xattr.h>
30 #include <linux/exportfs.h>
31 #include <linux/generic_acl.h>
33 #include <linux/mman.h>
34 #include <linux/file.h>
35 #include <linux/swap.h>
36 #include <linux/pagemap.h>
37 #include <linux/string.h>
38 #include <linux/slab.h>
39 #include <linux/backing-dev.h>
40 #include <linux/shmem_fs.h>
41 #include <linux/mount.h>
42 #include <linux/writeback.h>
43 #include <linux/vfs.h>
44 #include <linux/blkdev.h>
45 #include <linux/security.h>
46 #include <linux/swapops.h>
47 #include <linux/mempolicy.h>
48 #include <linux/namei.h>
49 #include <linux/ctype.h>
50 #include <linux/migrate.h>
51 #include <linux/highmem.h>
52 #include <linux/seq_file.h>
53 #include <linux/magic.h>
55 #include <asm/uaccess.h>
56 #include <asm/div64.h>
57 #include <asm/pgtable.h>
59 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
60 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
61 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
63 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
64 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
66 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
68 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
69 #define SHMEM_PAGEIN VM_READ
70 #define SHMEM_TRUNCATE VM_WRITE
72 /* Definition to limit shmem_truncate's steps between cond_rescheds */
73 #define LATENCY_LIMIT 64
75 /* Pretend that each entry is of this size in directory's i_size */
76 #define BOGO_DIRENT_SIZE 20
78 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
80 SGP_READ
, /* don't exceed i_size, don't allocate page */
81 SGP_CACHE
, /* don't exceed i_size, may allocate page */
82 SGP_DIRTY
, /* like SGP_CACHE, but set new page dirty */
83 SGP_WRITE
, /* may exceed i_size, may allocate page */
87 static unsigned long shmem_default_max_blocks(void)
89 return totalram_pages
/ 2;
92 static unsigned long shmem_default_max_inodes(void)
94 return min(totalram_pages
- totalhigh_pages
, totalram_pages
/ 2);
98 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
99 struct page
**pagep
, enum sgp_type sgp
, int *type
);
101 static inline struct page
*shmem_dir_alloc(gfp_t gfp_mask
)
104 * The above definition of ENTRIES_PER_PAGE, and the use of
105 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
106 * might be reconsidered if it ever diverges from PAGE_SIZE.
108 * Mobility flags are masked out as swap vectors cannot move
110 return alloc_pages((gfp_mask
& ~GFP_MOVABLE_MASK
) | __GFP_ZERO
,
111 PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
114 static inline void shmem_dir_free(struct page
*page
)
116 __free_pages(page
, PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
119 static struct page
**shmem_dir_map(struct page
*page
)
121 return (struct page
**)kmap_atomic(page
, KM_USER0
);
124 static inline void shmem_dir_unmap(struct page
**dir
)
126 kunmap_atomic(dir
, KM_USER0
);
129 static swp_entry_t
*shmem_swp_map(struct page
*page
)
131 return (swp_entry_t
*)kmap_atomic(page
, KM_USER1
);
134 static inline void shmem_swp_balance_unmap(void)
137 * When passing a pointer to an i_direct entry, to code which
138 * also handles indirect entries and so will shmem_swp_unmap,
139 * we must arrange for the preempt count to remain in balance.
140 * What kmap_atomic of a lowmem page does depends on config
141 * and architecture, so pretend to kmap_atomic some lowmem page.
143 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1
);
146 static inline void shmem_swp_unmap(swp_entry_t
*entry
)
148 kunmap_atomic(entry
, KM_USER1
);
151 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
153 return sb
->s_fs_info
;
157 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
158 * for shared memory and for shared anonymous (/dev/zero) mappings
159 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
160 * consistent with the pre-accounting of private mappings ...
162 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
164 return (flags
& VM_ACCOUNT
)?
165 security_vm_enough_memory(VM_ACCT(size
)): 0;
168 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
170 if (flags
& VM_ACCOUNT
)
171 vm_unacct_memory(VM_ACCT(size
));
175 * ... whereas tmpfs objects are accounted incrementally as
176 * pages are allocated, in order to allow huge sparse files.
177 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
178 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
180 static inline int shmem_acct_block(unsigned long flags
)
182 return (flags
& VM_ACCOUNT
)?
183 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE
));
186 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
188 if (!(flags
& VM_ACCOUNT
))
189 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
192 static const struct super_operations shmem_ops
;
193 static const struct address_space_operations shmem_aops
;
194 static const struct file_operations shmem_file_operations
;
195 static const struct inode_operations shmem_inode_operations
;
196 static const struct inode_operations shmem_dir_inode_operations
;
197 static const struct inode_operations shmem_special_inode_operations
;
198 static struct vm_operations_struct shmem_vm_ops
;
200 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
201 .ra_pages
= 0, /* No readahead */
202 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
,
203 .unplug_io_fn
= default_unplug_io_fn
,
206 static LIST_HEAD(shmem_swaplist
);
207 static DEFINE_MUTEX(shmem_swaplist_mutex
);
209 static void shmem_free_blocks(struct inode
*inode
, long pages
)
211 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
212 if (sbinfo
->max_blocks
) {
213 spin_lock(&sbinfo
->stat_lock
);
214 sbinfo
->free_blocks
+= pages
;
215 inode
->i_blocks
-= pages
*BLOCKS_PER_PAGE
;
216 spin_unlock(&sbinfo
->stat_lock
);
220 static int shmem_reserve_inode(struct super_block
*sb
)
222 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
223 if (sbinfo
->max_inodes
) {
224 spin_lock(&sbinfo
->stat_lock
);
225 if (!sbinfo
->free_inodes
) {
226 spin_unlock(&sbinfo
->stat_lock
);
229 sbinfo
->free_inodes
--;
230 spin_unlock(&sbinfo
->stat_lock
);
235 static void shmem_free_inode(struct super_block
*sb
)
237 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
238 if (sbinfo
->max_inodes
) {
239 spin_lock(&sbinfo
->stat_lock
);
240 sbinfo
->free_inodes
++;
241 spin_unlock(&sbinfo
->stat_lock
);
246 * shmem_recalc_inode - recalculate the size of an inode
247 * @inode: inode to recalc
249 * We have to calculate the free blocks since the mm can drop
250 * undirtied hole pages behind our back.
252 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
253 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
255 * It has to be called with the spinlock held.
257 static void shmem_recalc_inode(struct inode
*inode
)
259 struct shmem_inode_info
*info
= SHMEM_I(inode
);
262 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
264 info
->alloced
-= freed
;
265 shmem_unacct_blocks(info
->flags
, freed
);
266 shmem_free_blocks(inode
, freed
);
271 * shmem_swp_entry - find the swap vector position in the info structure
272 * @info: info structure for the inode
273 * @index: index of the page to find
274 * @page: optional page to add to the structure. Has to be preset to
277 * If there is no space allocated yet it will return NULL when
278 * page is NULL, else it will use the page for the needed block,
279 * setting it to NULL on return to indicate that it has been used.
281 * The swap vector is organized the following way:
283 * There are SHMEM_NR_DIRECT entries directly stored in the
284 * shmem_inode_info structure. So small files do not need an addional
287 * For pages with index > SHMEM_NR_DIRECT there is the pointer
288 * i_indirect which points to a page which holds in the first half
289 * doubly indirect blocks, in the second half triple indirect blocks:
291 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
292 * following layout (for SHMEM_NR_DIRECT == 16):
294 * i_indirect -> dir --> 16-19
307 static swp_entry_t
*shmem_swp_entry(struct shmem_inode_info
*info
, unsigned long index
, struct page
**page
)
309 unsigned long offset
;
313 if (index
< SHMEM_NR_DIRECT
) {
314 shmem_swp_balance_unmap();
315 return info
->i_direct
+index
;
317 if (!info
->i_indirect
) {
319 info
->i_indirect
= *page
;
322 return NULL
; /* need another page */
325 index
-= SHMEM_NR_DIRECT
;
326 offset
= index
% ENTRIES_PER_PAGE
;
327 index
/= ENTRIES_PER_PAGE
;
328 dir
= shmem_dir_map(info
->i_indirect
);
330 if (index
>= ENTRIES_PER_PAGE
/2) {
331 index
-= ENTRIES_PER_PAGE
/2;
332 dir
+= ENTRIES_PER_PAGE
/2 + index
/ENTRIES_PER_PAGE
;
333 index
%= ENTRIES_PER_PAGE
;
340 shmem_dir_unmap(dir
);
341 return NULL
; /* need another page */
343 shmem_dir_unmap(dir
);
344 dir
= shmem_dir_map(subdir
);
350 if (!page
|| !(subdir
= *page
)) {
351 shmem_dir_unmap(dir
);
352 return NULL
; /* need a page */
357 shmem_dir_unmap(dir
);
358 return shmem_swp_map(subdir
) + offset
;
361 static void shmem_swp_set(struct shmem_inode_info
*info
, swp_entry_t
*entry
, unsigned long value
)
363 long incdec
= value
? 1: -1;
366 info
->swapped
+= incdec
;
367 if ((unsigned long)(entry
- info
->i_direct
) >= SHMEM_NR_DIRECT
) {
368 struct page
*page
= kmap_atomic_to_page(entry
);
369 set_page_private(page
, page_private(page
) + incdec
);
374 * shmem_swp_alloc - get the position of the swap entry for the page.
375 * @info: info structure for the inode
376 * @index: index of the page to find
377 * @sgp: check and recheck i_size? skip allocation?
379 * If the entry does not exist, allocate it.
381 static swp_entry_t
*shmem_swp_alloc(struct shmem_inode_info
*info
, unsigned long index
, enum sgp_type sgp
)
383 struct inode
*inode
= &info
->vfs_inode
;
384 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
385 struct page
*page
= NULL
;
388 if (sgp
!= SGP_WRITE
&&
389 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
390 return ERR_PTR(-EINVAL
);
392 while (!(entry
= shmem_swp_entry(info
, index
, &page
))) {
394 return shmem_swp_map(ZERO_PAGE(0));
396 * Test free_blocks against 1 not 0, since we have 1 data
397 * page (and perhaps indirect index pages) yet to allocate:
398 * a waste to allocate index if we cannot allocate data.
400 if (sbinfo
->max_blocks
) {
401 spin_lock(&sbinfo
->stat_lock
);
402 if (sbinfo
->free_blocks
<= 1) {
403 spin_unlock(&sbinfo
->stat_lock
);
404 return ERR_PTR(-ENOSPC
);
406 sbinfo
->free_blocks
--;
407 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
408 spin_unlock(&sbinfo
->stat_lock
);
411 spin_unlock(&info
->lock
);
412 page
= shmem_dir_alloc(mapping_gfp_mask(inode
->i_mapping
));
414 set_page_private(page
, 0);
415 spin_lock(&info
->lock
);
418 shmem_free_blocks(inode
, 1);
419 return ERR_PTR(-ENOMEM
);
421 if (sgp
!= SGP_WRITE
&&
422 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
423 entry
= ERR_PTR(-EINVAL
);
426 if (info
->next_index
<= index
)
427 info
->next_index
= index
+ 1;
430 /* another task gave its page, or truncated the file */
431 shmem_free_blocks(inode
, 1);
432 shmem_dir_free(page
);
434 if (info
->next_index
<= index
&& !IS_ERR(entry
))
435 info
->next_index
= index
+ 1;
440 * shmem_free_swp - free some swap entries in a directory
441 * @dir: pointer to the directory
442 * @edir: pointer after last entry of the directory
443 * @punch_lock: pointer to spinlock when needed for the holepunch case
445 static int shmem_free_swp(swp_entry_t
*dir
, swp_entry_t
*edir
,
446 spinlock_t
*punch_lock
)
448 spinlock_t
*punch_unlock
= NULL
;
452 for (ptr
= dir
; ptr
< edir
; ptr
++) {
454 if (unlikely(punch_lock
)) {
455 punch_unlock
= punch_lock
;
457 spin_lock(punch_unlock
);
461 free_swap_and_cache(*ptr
);
462 *ptr
= (swp_entry_t
){0};
467 spin_unlock(punch_unlock
);
471 static int shmem_map_and_free_swp(struct page
*subdir
, int offset
,
472 int limit
, struct page
***dir
, spinlock_t
*punch_lock
)
477 ptr
= shmem_swp_map(subdir
);
478 for (; offset
< limit
; offset
+= LATENCY_LIMIT
) {
479 int size
= limit
- offset
;
480 if (size
> LATENCY_LIMIT
)
481 size
= LATENCY_LIMIT
;
482 freed
+= shmem_free_swp(ptr
+offset
, ptr
+offset
+size
,
484 if (need_resched()) {
485 shmem_swp_unmap(ptr
);
487 shmem_dir_unmap(*dir
);
491 ptr
= shmem_swp_map(subdir
);
494 shmem_swp_unmap(ptr
);
498 static void shmem_free_pages(struct list_head
*next
)
504 page
= container_of(next
, struct page
, lru
);
506 shmem_dir_free(page
);
508 if (freed
>= LATENCY_LIMIT
) {
515 static void shmem_truncate_range(struct inode
*inode
, loff_t start
, loff_t end
)
517 struct shmem_inode_info
*info
= SHMEM_I(inode
);
522 unsigned long diroff
;
528 LIST_HEAD(pages_to_free
);
529 long nr_pages_to_free
= 0;
530 long nr_swaps_freed
= 0;
534 spinlock_t
*needs_lock
;
535 spinlock_t
*punch_lock
;
536 unsigned long upper_limit
;
538 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
539 idx
= (start
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
540 if (idx
>= info
->next_index
)
543 spin_lock(&info
->lock
);
544 info
->flags
|= SHMEM_TRUNCATE
;
545 if (likely(end
== (loff_t
) -1)) {
546 limit
= info
->next_index
;
547 upper_limit
= SHMEM_MAX_INDEX
;
548 info
->next_index
= idx
;
552 if (end
+ 1 >= inode
->i_size
) { /* we may free a little more */
553 limit
= (inode
->i_size
+ PAGE_CACHE_SIZE
- 1) >>
555 upper_limit
= SHMEM_MAX_INDEX
;
557 limit
= (end
+ 1) >> PAGE_CACHE_SHIFT
;
560 needs_lock
= &info
->lock
;
564 topdir
= info
->i_indirect
;
565 if (topdir
&& idx
<= SHMEM_NR_DIRECT
&& !punch_hole
) {
566 info
->i_indirect
= NULL
;
568 list_add(&topdir
->lru
, &pages_to_free
);
570 spin_unlock(&info
->lock
);
572 if (info
->swapped
&& idx
< SHMEM_NR_DIRECT
) {
573 ptr
= info
->i_direct
;
575 if (size
> SHMEM_NR_DIRECT
)
576 size
= SHMEM_NR_DIRECT
;
577 nr_swaps_freed
= shmem_free_swp(ptr
+idx
, ptr
+size
, needs_lock
);
581 * If there are no indirect blocks or we are punching a hole
582 * below indirect blocks, nothing to be done.
584 if (!topdir
|| limit
<= SHMEM_NR_DIRECT
)
588 * The truncation case has already dropped info->lock, and we're safe
589 * because i_size and next_index have already been lowered, preventing
590 * access beyond. But in the punch_hole case, we still need to take
591 * the lock when updating the swap directory, because there might be
592 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
593 * shmem_writepage. However, whenever we find we can remove a whole
594 * directory page (not at the misaligned start or end of the range),
595 * we first NULLify its pointer in the level above, and then have no
596 * need to take the lock when updating its contents: needs_lock and
597 * punch_lock (either pointing to info->lock or NULL) manage this.
600 upper_limit
-= SHMEM_NR_DIRECT
;
601 limit
-= SHMEM_NR_DIRECT
;
602 idx
= (idx
> SHMEM_NR_DIRECT
)? (idx
- SHMEM_NR_DIRECT
): 0;
603 offset
= idx
% ENTRIES_PER_PAGE
;
606 dir
= shmem_dir_map(topdir
);
607 stage
= ENTRIES_PER_PAGEPAGE
/2;
608 if (idx
< ENTRIES_PER_PAGEPAGE
/2) {
610 diroff
= idx
/ENTRIES_PER_PAGE
;
612 dir
+= ENTRIES_PER_PAGE
/2;
613 dir
+= (idx
- ENTRIES_PER_PAGEPAGE
/2)/ENTRIES_PER_PAGEPAGE
;
615 stage
+= ENTRIES_PER_PAGEPAGE
;
618 diroff
= ((idx
- ENTRIES_PER_PAGEPAGE
/2) %
619 ENTRIES_PER_PAGEPAGE
) / ENTRIES_PER_PAGE
;
620 if (!diroff
&& !offset
&& upper_limit
>= stage
) {
622 spin_lock(needs_lock
);
624 spin_unlock(needs_lock
);
629 list_add(&middir
->lru
, &pages_to_free
);
631 shmem_dir_unmap(dir
);
632 dir
= shmem_dir_map(middir
);
640 for (; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, diroff
++) {
641 if (unlikely(idx
== stage
)) {
642 shmem_dir_unmap(dir
);
643 dir
= shmem_dir_map(topdir
) +
644 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
647 idx
+= ENTRIES_PER_PAGEPAGE
;
651 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
654 needs_lock
= &info
->lock
;
655 if (upper_limit
>= stage
) {
657 spin_lock(needs_lock
);
659 spin_unlock(needs_lock
);
664 list_add(&middir
->lru
, &pages_to_free
);
666 shmem_dir_unmap(dir
);
668 dir
= shmem_dir_map(middir
);
671 punch_lock
= needs_lock
;
672 subdir
= dir
[diroff
];
673 if (subdir
&& !offset
&& upper_limit
-idx
>= ENTRIES_PER_PAGE
) {
675 spin_lock(needs_lock
);
677 spin_unlock(needs_lock
);
682 list_add(&subdir
->lru
, &pages_to_free
);
684 if (subdir
&& page_private(subdir
) /* has swap entries */) {
686 if (size
> ENTRIES_PER_PAGE
)
687 size
= ENTRIES_PER_PAGE
;
688 freed
= shmem_map_and_free_swp(subdir
,
689 offset
, size
, &dir
, punch_lock
);
691 dir
= shmem_dir_map(middir
);
692 nr_swaps_freed
+= freed
;
693 if (offset
|| punch_lock
) {
694 spin_lock(&info
->lock
);
695 set_page_private(subdir
,
696 page_private(subdir
) - freed
);
697 spin_unlock(&info
->lock
);
699 BUG_ON(page_private(subdir
) != freed
);
704 shmem_dir_unmap(dir
);
706 if (inode
->i_mapping
->nrpages
&& (info
->flags
& SHMEM_PAGEIN
)) {
708 * Call truncate_inode_pages again: racing shmem_unuse_inode
709 * may have swizzled a page in from swap since vmtruncate or
710 * generic_delete_inode did it, before we lowered next_index.
711 * Also, though shmem_getpage checks i_size before adding to
712 * cache, no recheck after: so fix the narrow window there too.
714 * Recalling truncate_inode_pages_range and unmap_mapping_range
715 * every time for punch_hole (which never got a chance to clear
716 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
717 * yet hardly ever necessary: try to optimize them out later.
719 truncate_inode_pages_range(inode
->i_mapping
, start
, end
);
721 unmap_mapping_range(inode
->i_mapping
, start
,
725 spin_lock(&info
->lock
);
726 info
->flags
&= ~SHMEM_TRUNCATE
;
727 info
->swapped
-= nr_swaps_freed
;
728 if (nr_pages_to_free
)
729 shmem_free_blocks(inode
, nr_pages_to_free
);
730 shmem_recalc_inode(inode
);
731 spin_unlock(&info
->lock
);
734 * Empty swap vector directory pages to be freed?
736 if (!list_empty(&pages_to_free
)) {
737 pages_to_free
.prev
->next
= NULL
;
738 shmem_free_pages(pages_to_free
.next
);
742 static void shmem_truncate(struct inode
*inode
)
744 shmem_truncate_range(inode
, inode
->i_size
, (loff_t
)-1);
747 static int shmem_notify_change(struct dentry
*dentry
, struct iattr
*attr
)
749 struct inode
*inode
= dentry
->d_inode
;
750 struct page
*page
= NULL
;
753 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
754 if (attr
->ia_size
< inode
->i_size
) {
756 * If truncating down to a partial page, then
757 * if that page is already allocated, hold it
758 * in memory until the truncation is over, so
759 * truncate_partial_page cannnot miss it were
760 * it assigned to swap.
762 if (attr
->ia_size
& (PAGE_CACHE_SIZE
-1)) {
763 (void) shmem_getpage(inode
,
764 attr
->ia_size
>>PAGE_CACHE_SHIFT
,
765 &page
, SGP_READ
, NULL
);
770 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
771 * detect if any pages might have been added to cache
772 * after truncate_inode_pages. But we needn't bother
773 * if it's being fully truncated to zero-length: the
774 * nrpages check is efficient enough in that case.
777 struct shmem_inode_info
*info
= SHMEM_I(inode
);
778 spin_lock(&info
->lock
);
779 info
->flags
&= ~SHMEM_PAGEIN
;
780 spin_unlock(&info
->lock
);
785 error
= inode_change_ok(inode
, attr
);
787 error
= inode_setattr(inode
, attr
);
788 #ifdef CONFIG_TMPFS_POSIX_ACL
789 if (!error
&& (attr
->ia_valid
& ATTR_MODE
))
790 error
= generic_acl_chmod(inode
, &shmem_acl_ops
);
793 page_cache_release(page
);
797 static void shmem_delete_inode(struct inode
*inode
)
799 struct shmem_inode_info
*info
= SHMEM_I(inode
);
801 if (inode
->i_op
->truncate
== shmem_truncate
) {
802 truncate_inode_pages(inode
->i_mapping
, 0);
803 shmem_unacct_size(info
->flags
, inode
->i_size
);
805 shmem_truncate(inode
);
806 if (!list_empty(&info
->swaplist
)) {
807 mutex_lock(&shmem_swaplist_mutex
);
808 list_del_init(&info
->swaplist
);
809 mutex_unlock(&shmem_swaplist_mutex
);
812 BUG_ON(inode
->i_blocks
);
813 shmem_free_inode(inode
->i_sb
);
817 static inline int shmem_find_swp(swp_entry_t entry
, swp_entry_t
*dir
, swp_entry_t
*edir
)
821 for (ptr
= dir
; ptr
< edir
; ptr
++) {
822 if (ptr
->val
== entry
.val
)
828 static int shmem_unuse_inode(struct shmem_inode_info
*info
, swp_entry_t entry
, struct page
*page
)
842 ptr
= info
->i_direct
;
843 spin_lock(&info
->lock
);
844 if (!info
->swapped
) {
845 list_del_init(&info
->swaplist
);
848 limit
= info
->next_index
;
850 if (size
> SHMEM_NR_DIRECT
)
851 size
= SHMEM_NR_DIRECT
;
852 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
855 if (!info
->i_indirect
)
858 dir
= shmem_dir_map(info
->i_indirect
);
859 stage
= SHMEM_NR_DIRECT
+ ENTRIES_PER_PAGEPAGE
/2;
861 for (idx
= SHMEM_NR_DIRECT
; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, dir
++) {
862 if (unlikely(idx
== stage
)) {
863 shmem_dir_unmap(dir
-1);
864 if (cond_resched_lock(&info
->lock
)) {
865 /* check it has not been truncated */
866 if (limit
> info
->next_index
) {
867 limit
= info
->next_index
;
872 dir
= shmem_dir_map(info
->i_indirect
) +
873 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
876 idx
+= ENTRIES_PER_PAGEPAGE
;
880 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
882 shmem_dir_unmap(dir
);
883 dir
= shmem_dir_map(subdir
);
886 if (subdir
&& page_private(subdir
)) {
887 ptr
= shmem_swp_map(subdir
);
889 if (size
> ENTRIES_PER_PAGE
)
890 size
= ENTRIES_PER_PAGE
;
891 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
892 shmem_swp_unmap(ptr
);
894 shmem_dir_unmap(dir
);
900 shmem_dir_unmap(dir
-1);
902 spin_unlock(&info
->lock
);
906 inode
= igrab(&info
->vfs_inode
);
907 spin_unlock(&info
->lock
);
910 * Move _head_ to start search for next from here.
911 * But be careful: shmem_delete_inode checks list_empty without taking
912 * mutex, and there's an instant in list_move_tail when info->swaplist
913 * would appear empty, if it were the only one on shmem_swaplist. We
914 * could avoid doing it if inode NULL; or use this minor optimization.
916 if (shmem_swaplist
.next
!= &info
->swaplist
)
917 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
918 mutex_unlock(&shmem_swaplist_mutex
);
923 /* Precharge page using GFP_KERNEL while we can wait */
924 error
= mem_cgroup_cache_charge(page
, current
->mm
, GFP_KERNEL
);
927 error
= radix_tree_preload(GFP_KERNEL
);
929 mem_cgroup_uncharge_cache_page(page
);
934 spin_lock(&info
->lock
);
935 ptr
= shmem_swp_entry(info
, idx
, NULL
);
936 if (ptr
&& ptr
->val
== entry
.val
) {
937 error
= add_to_page_cache_locked(page
, inode
->i_mapping
,
939 /* does mem_cgroup_uncharge_cache_page on error */
940 } else /* we must compensate for our precharge above */
941 mem_cgroup_uncharge_cache_page(page
);
943 if (error
== -EEXIST
) {
944 struct page
*filepage
= find_get_page(inode
->i_mapping
, idx
);
948 * There might be a more uptodate page coming down
949 * from a stacked writepage: forget our swappage if so.
951 if (PageUptodate(filepage
))
953 page_cache_release(filepage
);
957 delete_from_swap_cache(page
);
958 set_page_dirty(page
);
959 info
->flags
|= SHMEM_PAGEIN
;
960 shmem_swp_set(info
, ptr
, 0);
962 error
= 1; /* not an error, but entry was found */
965 shmem_swp_unmap(ptr
);
966 spin_unlock(&info
->lock
);
967 radix_tree_preload_end();
970 page_cache_release(page
);
971 iput(inode
); /* allows for NULL */
976 * shmem_unuse() search for an eventually swapped out shmem page.
978 int shmem_unuse(swp_entry_t entry
, struct page
*page
)
980 struct list_head
*p
, *next
;
981 struct shmem_inode_info
*info
;
984 mutex_lock(&shmem_swaplist_mutex
);
985 list_for_each_safe(p
, next
, &shmem_swaplist
) {
986 info
= list_entry(p
, struct shmem_inode_info
, swaplist
);
987 found
= shmem_unuse_inode(info
, entry
, page
);
992 mutex_unlock(&shmem_swaplist_mutex
);
993 out
: return found
; /* 0 or 1 or -ENOMEM */
997 * Move the page from the page cache to the swap cache.
999 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
1001 struct shmem_inode_info
*info
;
1002 swp_entry_t
*entry
, swap
;
1003 struct address_space
*mapping
;
1004 unsigned long index
;
1005 struct inode
*inode
;
1007 BUG_ON(!PageLocked(page
));
1008 mapping
= page
->mapping
;
1009 index
= page
->index
;
1010 inode
= mapping
->host
;
1011 info
= SHMEM_I(inode
);
1012 if (info
->flags
& VM_LOCKED
)
1014 if (!total_swap_pages
)
1018 * shmem_backing_dev_info's capabilities prevent regular writeback or
1019 * sync from ever calling shmem_writepage; but a stacking filesystem
1020 * may use the ->writepage of its underlying filesystem, in which case
1021 * tmpfs should write out to swap only in response to memory pressure,
1022 * and not for pdflush or sync. However, in those cases, we do still
1023 * want to check if there's a redundant swappage to be discarded.
1025 if (wbc
->for_reclaim
)
1026 swap
= get_swap_page();
1030 spin_lock(&info
->lock
);
1031 if (index
>= info
->next_index
) {
1032 BUG_ON(!(info
->flags
& SHMEM_TRUNCATE
));
1035 entry
= shmem_swp_entry(info
, index
, NULL
);
1038 * The more uptodate page coming down from a stacked
1039 * writepage should replace our old swappage.
1041 free_swap_and_cache(*entry
);
1042 shmem_swp_set(info
, entry
, 0);
1044 shmem_recalc_inode(inode
);
1046 if (swap
.val
&& add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
1047 remove_from_page_cache(page
);
1048 shmem_swp_set(info
, entry
, swap
.val
);
1049 shmem_swp_unmap(entry
);
1050 if (list_empty(&info
->swaplist
))
1051 inode
= igrab(inode
);
1054 spin_unlock(&info
->lock
);
1055 swap_duplicate(swap
);
1056 BUG_ON(page_mapped(page
));
1057 page_cache_release(page
); /* pagecache ref */
1058 set_page_dirty(page
);
1061 mutex_lock(&shmem_swaplist_mutex
);
1062 /* move instead of add in case we're racing */
1063 list_move_tail(&info
->swaplist
, &shmem_swaplist
);
1064 mutex_unlock(&shmem_swaplist_mutex
);
1070 shmem_swp_unmap(entry
);
1072 spin_unlock(&info
->lock
);
1075 set_page_dirty(page
);
1076 if (wbc
->for_reclaim
)
1077 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
1084 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
1088 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
1089 return; /* show nothing */
1091 mpol_to_str(buffer
, sizeof(buffer
), mpol
, 1);
1093 seq_printf(seq
, ",mpol=%s", buffer
);
1096 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
1098 struct mempolicy
*mpol
= NULL
;
1100 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
1101 mpol
= sbinfo
->mpol
;
1103 spin_unlock(&sbinfo
->stat_lock
);
1107 #endif /* CONFIG_TMPFS */
1109 static struct page
*shmem_swapin(swp_entry_t entry
, gfp_t gfp
,
1110 struct shmem_inode_info
*info
, unsigned long idx
)
1112 struct mempolicy mpol
, *spol
;
1113 struct vm_area_struct pvma
;
1116 spol
= mpol_cond_copy(&mpol
,
1117 mpol_shared_policy_lookup(&info
->policy
, idx
));
1119 /* Create a pseudo vma that just contains the policy */
1121 pvma
.vm_pgoff
= idx
;
1123 pvma
.vm_policy
= spol
;
1124 page
= swapin_readahead(entry
, gfp
, &pvma
, 0);
1128 static struct page
*shmem_alloc_page(gfp_t gfp
,
1129 struct shmem_inode_info
*info
, unsigned long idx
)
1131 struct vm_area_struct pvma
;
1133 /* Create a pseudo vma that just contains the policy */
1135 pvma
.vm_pgoff
= idx
;
1137 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, idx
);
1140 * alloc_page_vma() will drop the shared policy reference
1142 return alloc_page_vma(gfp
, &pvma
, 0);
1144 #else /* !CONFIG_NUMA */
1146 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*p
)
1149 #endif /* CONFIG_TMPFS */
1151 static inline struct page
*shmem_swapin(swp_entry_t entry
, gfp_t gfp
,
1152 struct shmem_inode_info
*info
, unsigned long idx
)
1154 return swapin_readahead(entry
, gfp
, NULL
, 0);
1157 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
1158 struct shmem_inode_info
*info
, unsigned long idx
)
1160 return alloc_page(gfp
);
1162 #endif /* CONFIG_NUMA */
1164 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1165 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
1172 * shmem_getpage - either get the page from swap or allocate a new one
1174 * If we allocate a new one we do not mark it dirty. That's up to the
1175 * vm. If we swap it in we mark it dirty since we also free the swap
1176 * entry since a page cannot live in both the swap and page cache
1178 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
1179 struct page
**pagep
, enum sgp_type sgp
, int *type
)
1181 struct address_space
*mapping
= inode
->i_mapping
;
1182 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1183 struct shmem_sb_info
*sbinfo
;
1184 struct page
*filepage
= *pagep
;
1185 struct page
*swappage
;
1191 if (idx
>= SHMEM_MAX_INDEX
)
1198 * Normally, filepage is NULL on entry, and either found
1199 * uptodate immediately, or allocated and zeroed, or read
1200 * in under swappage, which is then assigned to filepage.
1201 * But shmem_readpage (required for splice) passes in a locked
1202 * filepage, which may be found not uptodate by other callers
1203 * too, and may need to be copied from the swappage read in.
1207 filepage
= find_lock_page(mapping
, idx
);
1208 if (filepage
&& PageUptodate(filepage
))
1211 gfp
= mapping_gfp_mask(mapping
);
1214 * Try to preload while we can wait, to not make a habit of
1215 * draining atomic reserves; but don't latch on to this cpu.
1217 error
= radix_tree_preload(gfp
& ~__GFP_HIGHMEM
);
1220 radix_tree_preload_end();
1223 spin_lock(&info
->lock
);
1224 shmem_recalc_inode(inode
);
1225 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1226 if (IS_ERR(entry
)) {
1227 spin_unlock(&info
->lock
);
1228 error
= PTR_ERR(entry
);
1234 /* Look it up and read it in.. */
1235 swappage
= lookup_swap_cache(swap
);
1237 shmem_swp_unmap(entry
);
1238 /* here we actually do the io */
1239 if (type
&& !(*type
& VM_FAULT_MAJOR
)) {
1240 __count_vm_event(PGMAJFAULT
);
1241 *type
|= VM_FAULT_MAJOR
;
1243 spin_unlock(&info
->lock
);
1244 swappage
= shmem_swapin(swap
, gfp
, info
, idx
);
1246 spin_lock(&info
->lock
);
1247 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1249 error
= PTR_ERR(entry
);
1251 if (entry
->val
== swap
.val
)
1253 shmem_swp_unmap(entry
);
1255 spin_unlock(&info
->lock
);
1260 wait_on_page_locked(swappage
);
1261 page_cache_release(swappage
);
1265 /* We have to do this with page locked to prevent races */
1266 if (!trylock_page(swappage
)) {
1267 shmem_swp_unmap(entry
);
1268 spin_unlock(&info
->lock
);
1269 wait_on_page_locked(swappage
);
1270 page_cache_release(swappage
);
1273 if (PageWriteback(swappage
)) {
1274 shmem_swp_unmap(entry
);
1275 spin_unlock(&info
->lock
);
1276 wait_on_page_writeback(swappage
);
1277 unlock_page(swappage
);
1278 page_cache_release(swappage
);
1281 if (!PageUptodate(swappage
)) {
1282 shmem_swp_unmap(entry
);
1283 spin_unlock(&info
->lock
);
1284 unlock_page(swappage
);
1285 page_cache_release(swappage
);
1291 shmem_swp_set(info
, entry
, 0);
1292 shmem_swp_unmap(entry
);
1293 delete_from_swap_cache(swappage
);
1294 spin_unlock(&info
->lock
);
1295 copy_highpage(filepage
, swappage
);
1296 unlock_page(swappage
);
1297 page_cache_release(swappage
);
1298 flush_dcache_page(filepage
);
1299 SetPageUptodate(filepage
);
1300 set_page_dirty(filepage
);
1302 } else if (!(error
= add_to_page_cache_locked(swappage
, mapping
,
1303 idx
, GFP_NOWAIT
))) {
1304 info
->flags
|= SHMEM_PAGEIN
;
1305 shmem_swp_set(info
, entry
, 0);
1306 shmem_swp_unmap(entry
);
1307 delete_from_swap_cache(swappage
);
1308 spin_unlock(&info
->lock
);
1309 filepage
= swappage
;
1310 set_page_dirty(filepage
);
1313 shmem_swp_unmap(entry
);
1314 spin_unlock(&info
->lock
);
1315 unlock_page(swappage
);
1316 page_cache_release(swappage
);
1317 if (error
== -ENOMEM
) {
1318 /* allow reclaim from this memory cgroup */
1319 error
= mem_cgroup_shrink_usage(current
->mm
,
1326 } else if (sgp
== SGP_READ
&& !filepage
) {
1327 shmem_swp_unmap(entry
);
1328 filepage
= find_get_page(mapping
, idx
);
1330 (!PageUptodate(filepage
) || !trylock_page(filepage
))) {
1331 spin_unlock(&info
->lock
);
1332 wait_on_page_locked(filepage
);
1333 page_cache_release(filepage
);
1337 spin_unlock(&info
->lock
);
1339 shmem_swp_unmap(entry
);
1340 sbinfo
= SHMEM_SB(inode
->i_sb
);
1341 if (sbinfo
->max_blocks
) {
1342 spin_lock(&sbinfo
->stat_lock
);
1343 if (sbinfo
->free_blocks
== 0 ||
1344 shmem_acct_block(info
->flags
)) {
1345 spin_unlock(&sbinfo
->stat_lock
);
1346 spin_unlock(&info
->lock
);
1350 sbinfo
->free_blocks
--;
1351 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1352 spin_unlock(&sbinfo
->stat_lock
);
1353 } else if (shmem_acct_block(info
->flags
)) {
1354 spin_unlock(&info
->lock
);
1362 spin_unlock(&info
->lock
);
1363 filepage
= shmem_alloc_page(gfp
, info
, idx
);
1365 shmem_unacct_blocks(info
->flags
, 1);
1366 shmem_free_blocks(inode
, 1);
1371 /* Precharge page while we can wait, compensate after */
1372 error
= mem_cgroup_cache_charge(filepage
, current
->mm
,
1373 gfp
& ~__GFP_HIGHMEM
);
1375 page_cache_release(filepage
);
1376 shmem_unacct_blocks(info
->flags
, 1);
1377 shmem_free_blocks(inode
, 1);
1382 spin_lock(&info
->lock
);
1383 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1385 error
= PTR_ERR(entry
);
1388 shmem_swp_unmap(entry
);
1390 ret
= error
|| swap
.val
;
1392 mem_cgroup_uncharge_cache_page(filepage
);
1394 ret
= add_to_page_cache_lru(filepage
, mapping
,
1397 * At add_to_page_cache_lru() failure, uncharge will
1398 * be done automatically.
1401 spin_unlock(&info
->lock
);
1402 page_cache_release(filepage
);
1403 shmem_unacct_blocks(info
->flags
, 1);
1404 shmem_free_blocks(inode
, 1);
1410 info
->flags
|= SHMEM_PAGEIN
;
1414 spin_unlock(&info
->lock
);
1415 clear_highpage(filepage
);
1416 flush_dcache_page(filepage
);
1417 SetPageUptodate(filepage
);
1418 if (sgp
== SGP_DIRTY
)
1419 set_page_dirty(filepage
);
1426 if (*pagep
!= filepage
) {
1427 unlock_page(filepage
);
1428 page_cache_release(filepage
);
1433 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1435 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1439 if (((loff_t
)vmf
->pgoff
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
1440 return VM_FAULT_SIGBUS
;
1442 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1444 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1446 mark_page_accessed(vmf
->page
);
1447 return ret
| VM_FAULT_LOCKED
;
1451 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*new)
1453 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1454 return mpol_set_shared_policy(&SHMEM_I(i
)->policy
, vma
, new);
1457 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1460 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1463 idx
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1464 return mpol_shared_policy_lookup(&SHMEM_I(i
)->policy
, idx
);
1468 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1470 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1471 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1472 int retval
= -ENOMEM
;
1474 spin_lock(&info
->lock
);
1475 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1476 if (!user_shm_lock(inode
->i_size
, user
))
1478 info
->flags
|= VM_LOCKED
;
1480 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1481 user_shm_unlock(inode
->i_size
, user
);
1482 info
->flags
&= ~VM_LOCKED
;
1486 spin_unlock(&info
->lock
);
1490 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1492 file_accessed(file
);
1493 vma
->vm_ops
= &shmem_vm_ops
;
1494 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1498 static struct inode
*
1499 shmem_get_inode(struct super_block
*sb
, int mode
, dev_t dev
)
1501 struct inode
*inode
;
1502 struct shmem_inode_info
*info
;
1503 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1505 if (shmem_reserve_inode(sb
))
1508 inode
= new_inode(sb
);
1510 inode
->i_mode
= mode
;
1511 inode
->i_uid
= current
->fsuid
;
1512 inode
->i_gid
= current
->fsgid
;
1513 inode
->i_blocks
= 0;
1514 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1515 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1516 inode
->i_generation
= get_seconds();
1517 info
= SHMEM_I(inode
);
1518 memset(info
, 0, (char *)inode
- (char *)info
);
1519 spin_lock_init(&info
->lock
);
1520 INIT_LIST_HEAD(&info
->swaplist
);
1522 switch (mode
& S_IFMT
) {
1524 inode
->i_op
= &shmem_special_inode_operations
;
1525 init_special_inode(inode
, mode
, dev
);
1528 inode
->i_mapping
->a_ops
= &shmem_aops
;
1529 inode
->i_op
= &shmem_inode_operations
;
1530 inode
->i_fop
= &shmem_file_operations
;
1531 mpol_shared_policy_init(&info
->policy
,
1532 shmem_get_sbmpol(sbinfo
));
1536 /* Some things misbehave if size == 0 on a directory */
1537 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1538 inode
->i_op
= &shmem_dir_inode_operations
;
1539 inode
->i_fop
= &simple_dir_operations
;
1543 * Must not load anything in the rbtree,
1544 * mpol_free_shared_policy will not be called.
1546 mpol_shared_policy_init(&info
->policy
, NULL
);
1550 shmem_free_inode(sb
);
1555 static const struct inode_operations shmem_symlink_inode_operations
;
1556 static const struct inode_operations shmem_symlink_inline_operations
;
1559 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1560 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1561 * below the loop driver, in the generic fashion that many filesystems support.
1563 static int shmem_readpage(struct file
*file
, struct page
*page
)
1565 struct inode
*inode
= page
->mapping
->host
;
1566 int error
= shmem_getpage(inode
, page
->index
, &page
, SGP_CACHE
, NULL
);
1572 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1573 loff_t pos
, unsigned len
, unsigned flags
,
1574 struct page
**pagep
, void **fsdata
)
1576 struct inode
*inode
= mapping
->host
;
1577 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1579 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1583 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1584 loff_t pos
, unsigned len
, unsigned copied
,
1585 struct page
*page
, void *fsdata
)
1587 struct inode
*inode
= mapping
->host
;
1589 if (pos
+ copied
> inode
->i_size
)
1590 i_size_write(inode
, pos
+ copied
);
1593 set_page_dirty(page
);
1594 page_cache_release(page
);
1599 static void do_shmem_file_read(struct file
*filp
, loff_t
*ppos
, read_descriptor_t
*desc
, read_actor_t actor
)
1601 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
1602 struct address_space
*mapping
= inode
->i_mapping
;
1603 unsigned long index
, offset
;
1604 enum sgp_type sgp
= SGP_READ
;
1607 * Might this read be for a stacking filesystem? Then when reading
1608 * holes of a sparse file, we actually need to allocate those pages,
1609 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1611 if (segment_eq(get_fs(), KERNEL_DS
))
1614 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1615 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1618 struct page
*page
= NULL
;
1619 unsigned long end_index
, nr
, ret
;
1620 loff_t i_size
= i_size_read(inode
);
1622 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1623 if (index
> end_index
)
1625 if (index
== end_index
) {
1626 nr
= i_size
& ~PAGE_CACHE_MASK
;
1631 desc
->error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1633 if (desc
->error
== -EINVAL
)
1641 * We must evaluate after, since reads (unlike writes)
1642 * are called without i_mutex protection against truncate
1644 nr
= PAGE_CACHE_SIZE
;
1645 i_size
= i_size_read(inode
);
1646 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1647 if (index
== end_index
) {
1648 nr
= i_size
& ~PAGE_CACHE_MASK
;
1651 page_cache_release(page
);
1659 * If users can be writing to this page using arbitrary
1660 * virtual addresses, take care about potential aliasing
1661 * before reading the page on the kernel side.
1663 if (mapping_writably_mapped(mapping
))
1664 flush_dcache_page(page
);
1666 * Mark the page accessed if we read the beginning.
1669 mark_page_accessed(page
);
1671 page
= ZERO_PAGE(0);
1672 page_cache_get(page
);
1676 * Ok, we have the page, and it's up-to-date, so
1677 * now we can copy it to user space...
1679 * The actor routine returns how many bytes were actually used..
1680 * NOTE! This may not be the same as how much of a user buffer
1681 * we filled up (we may be padding etc), so we can only update
1682 * "pos" here (the actor routine has to update the user buffer
1683 * pointers and the remaining count).
1685 ret
= actor(desc
, page
, offset
, nr
);
1687 index
+= offset
>> PAGE_CACHE_SHIFT
;
1688 offset
&= ~PAGE_CACHE_MASK
;
1690 page_cache_release(page
);
1691 if (ret
!= nr
|| !desc
->count
)
1697 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1698 file_accessed(filp
);
1701 static ssize_t
shmem_file_aio_read(struct kiocb
*iocb
,
1702 const struct iovec
*iov
, unsigned long nr_segs
, loff_t pos
)
1704 struct file
*filp
= iocb
->ki_filp
;
1708 loff_t
*ppos
= &iocb
->ki_pos
;
1710 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1714 for (seg
= 0; seg
< nr_segs
; seg
++) {
1715 read_descriptor_t desc
;
1718 desc
.arg
.buf
= iov
[seg
].iov_base
;
1719 desc
.count
= iov
[seg
].iov_len
;
1720 if (desc
.count
== 0)
1723 do_shmem_file_read(filp
, ppos
, &desc
, file_read_actor
);
1724 retval
+= desc
.written
;
1726 retval
= retval
?: desc
.error
;
1735 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1737 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1739 buf
->f_type
= TMPFS_MAGIC
;
1740 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1741 buf
->f_namelen
= NAME_MAX
;
1742 spin_lock(&sbinfo
->stat_lock
);
1743 if (sbinfo
->max_blocks
) {
1744 buf
->f_blocks
= sbinfo
->max_blocks
;
1745 buf
->f_bavail
= buf
->f_bfree
= sbinfo
->free_blocks
;
1747 if (sbinfo
->max_inodes
) {
1748 buf
->f_files
= sbinfo
->max_inodes
;
1749 buf
->f_ffree
= sbinfo
->free_inodes
;
1751 /* else leave those fields 0 like simple_statfs */
1752 spin_unlock(&sbinfo
->stat_lock
);
1757 * File creation. Allocate an inode, and we're done..
1760 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1762 struct inode
*inode
= shmem_get_inode(dir
->i_sb
, mode
, dev
);
1763 int error
= -ENOSPC
;
1766 error
= security_inode_init_security(inode
, dir
, NULL
, NULL
,
1769 if (error
!= -EOPNOTSUPP
) {
1774 error
= shmem_acl_init(inode
, dir
);
1779 if (dir
->i_mode
& S_ISGID
) {
1780 inode
->i_gid
= dir
->i_gid
;
1782 inode
->i_mode
|= S_ISGID
;
1784 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1785 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1786 d_instantiate(dentry
, inode
);
1787 dget(dentry
); /* Extra count - pin the dentry in core */
1792 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1796 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1802 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1803 struct nameidata
*nd
)
1805 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
1811 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
1813 struct inode
*inode
= old_dentry
->d_inode
;
1817 * No ordinary (disk based) filesystem counts links as inodes;
1818 * but each new link needs a new dentry, pinning lowmem, and
1819 * tmpfs dentries cannot be pruned until they are unlinked.
1821 ret
= shmem_reserve_inode(inode
->i_sb
);
1825 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1826 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1828 atomic_inc(&inode
->i_count
); /* New dentry reference */
1829 dget(dentry
); /* Extra pinning count for the created dentry */
1830 d_instantiate(dentry
, inode
);
1835 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
1837 struct inode
*inode
= dentry
->d_inode
;
1839 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
1840 shmem_free_inode(inode
->i_sb
);
1842 dir
->i_size
-= BOGO_DIRENT_SIZE
;
1843 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1845 dput(dentry
); /* Undo the count from "create" - this does all the work */
1849 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1851 if (!simple_empty(dentry
))
1854 drop_nlink(dentry
->d_inode
);
1856 return shmem_unlink(dir
, dentry
);
1860 * The VFS layer already does all the dentry stuff for rename,
1861 * we just have to decrement the usage count for the target if
1862 * it exists so that the VFS layer correctly free's it when it
1865 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
1867 struct inode
*inode
= old_dentry
->d_inode
;
1868 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
1870 if (!simple_empty(new_dentry
))
1873 if (new_dentry
->d_inode
) {
1874 (void) shmem_unlink(new_dir
, new_dentry
);
1876 drop_nlink(old_dir
);
1877 } else if (they_are_dirs
) {
1878 drop_nlink(old_dir
);
1882 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
1883 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
1884 old_dir
->i_ctime
= old_dir
->i_mtime
=
1885 new_dir
->i_ctime
= new_dir
->i_mtime
=
1886 inode
->i_ctime
= CURRENT_TIME
;
1890 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
1894 struct inode
*inode
;
1895 struct page
*page
= NULL
;
1897 struct shmem_inode_info
*info
;
1899 len
= strlen(symname
) + 1;
1900 if (len
> PAGE_CACHE_SIZE
)
1901 return -ENAMETOOLONG
;
1903 inode
= shmem_get_inode(dir
->i_sb
, S_IFLNK
|S_IRWXUGO
, 0);
1907 error
= security_inode_init_security(inode
, dir
, NULL
, NULL
,
1910 if (error
!= -EOPNOTSUPP
) {
1917 info
= SHMEM_I(inode
);
1918 inode
->i_size
= len
-1;
1919 if (len
<= (char *)inode
- (char *)info
) {
1921 memcpy(info
, symname
, len
);
1922 inode
->i_op
= &shmem_symlink_inline_operations
;
1924 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
1930 inode
->i_mapping
->a_ops
= &shmem_aops
;
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
));
1963 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
1965 if (!IS_ERR(nd_get_link(nd
))) {
1966 struct page
*page
= cookie
;
1968 mark_page_accessed(page
);
1969 page_cache_release(page
);
1973 static const struct inode_operations shmem_symlink_inline_operations
= {
1974 .readlink
= generic_readlink
,
1975 .follow_link
= shmem_follow_link_inline
,
1978 static const struct inode_operations shmem_symlink_inode_operations
= {
1979 .truncate
= shmem_truncate
,
1980 .readlink
= generic_readlink
,
1981 .follow_link
= shmem_follow_link
,
1982 .put_link
= shmem_put_link
,
1985 #ifdef CONFIG_TMPFS_POSIX_ACL
1987 * Superblocks without xattr inode operations will get security.* xattr
1988 * support from the VFS "for free". As soon as we have any other xattrs
1989 * like ACLs, we also need to implement the security.* handlers at
1990 * filesystem level, though.
1993 static size_t shmem_xattr_security_list(struct inode
*inode
, char *list
,
1994 size_t list_len
, const char *name
,
1997 return security_inode_listsecurity(inode
, list
, list_len
);
2000 static int shmem_xattr_security_get(struct inode
*inode
, const char *name
,
2001 void *buffer
, size_t size
)
2003 if (strcmp(name
, "") == 0)
2005 return xattr_getsecurity(inode
, name
, buffer
, size
);
2008 static int shmem_xattr_security_set(struct inode
*inode
, const char *name
,
2009 const void *value
, size_t size
, int flags
)
2011 if (strcmp(name
, "") == 0)
2013 return security_inode_setsecurity(inode
, name
, value
, size
, flags
);
2016 static struct xattr_handler shmem_xattr_security_handler
= {
2017 .prefix
= XATTR_SECURITY_PREFIX
,
2018 .list
= shmem_xattr_security_list
,
2019 .get
= shmem_xattr_security_get
,
2020 .set
= shmem_xattr_security_set
,
2023 static struct xattr_handler
*shmem_xattr_handlers
[] = {
2024 &shmem_xattr_acl_access_handler
,
2025 &shmem_xattr_acl_default_handler
,
2026 &shmem_xattr_security_handler
,
2031 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2033 return ERR_PTR(-ESTALE
);
2036 static int shmem_match(struct inode
*ino
, void *vfh
)
2040 inum
= (inum
<< 32) | fh
[1];
2041 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2044 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
2045 struct fid
*fid
, int fh_len
, int fh_type
)
2047 struct inode
*inode
;
2048 struct dentry
*dentry
= NULL
;
2049 u64 inum
= fid
->raw
[2];
2050 inum
= (inum
<< 32) | fid
->raw
[1];
2055 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
2056 shmem_match
, fid
->raw
);
2058 dentry
= d_find_alias(inode
);
2065 static int shmem_encode_fh(struct dentry
*dentry
, __u32
*fh
, int *len
,
2068 struct inode
*inode
= dentry
->d_inode
;
2073 if (hlist_unhashed(&inode
->i_hash
)) {
2074 /* Unfortunately insert_inode_hash is not idempotent,
2075 * so as we hash inodes here rather than at creation
2076 * time, we need a lock to ensure we only try
2079 static DEFINE_SPINLOCK(lock
);
2081 if (hlist_unhashed(&inode
->i_hash
))
2082 __insert_inode_hash(inode
,
2083 inode
->i_ino
+ inode
->i_generation
);
2087 fh
[0] = inode
->i_generation
;
2088 fh
[1] = inode
->i_ino
;
2089 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2095 static const struct export_operations shmem_export_ops
= {
2096 .get_parent
= shmem_get_parent
,
2097 .encode_fh
= shmem_encode_fh
,
2098 .fh_to_dentry
= shmem_fh_to_dentry
,
2101 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2104 char *this_char
, *value
, *rest
;
2106 while (options
!= NULL
) {
2107 this_char
= options
;
2110 * NUL-terminate this option: unfortunately,
2111 * mount options form a comma-separated list,
2112 * but mpol's nodelist may also contain commas.
2114 options
= strchr(options
, ',');
2115 if (options
== NULL
)
2118 if (!isdigit(*options
)) {
2125 if ((value
= strchr(this_char
,'=')) != NULL
) {
2129 "tmpfs: No value for mount option '%s'\n",
2134 if (!strcmp(this_char
,"size")) {
2135 unsigned long long size
;
2136 size
= memparse(value
,&rest
);
2138 size
<<= PAGE_SHIFT
;
2139 size
*= totalram_pages
;
2145 sbinfo
->max_blocks
=
2146 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2147 } else if (!strcmp(this_char
,"nr_blocks")) {
2148 sbinfo
->max_blocks
= memparse(value
, &rest
);
2151 } else if (!strcmp(this_char
,"nr_inodes")) {
2152 sbinfo
->max_inodes
= memparse(value
, &rest
);
2155 } else if (!strcmp(this_char
,"mode")) {
2158 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2161 } else if (!strcmp(this_char
,"uid")) {
2164 sbinfo
->uid
= simple_strtoul(value
, &rest
, 0);
2167 } else if (!strcmp(this_char
,"gid")) {
2170 sbinfo
->gid
= simple_strtoul(value
, &rest
, 0);
2173 } else if (!strcmp(this_char
,"mpol")) {
2174 if (mpol_parse_str(value
, &sbinfo
->mpol
, 1))
2177 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2185 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2191 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2193 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2194 struct shmem_sb_info config
= *sbinfo
;
2195 unsigned long blocks
;
2196 unsigned long inodes
;
2197 int error
= -EINVAL
;
2199 if (shmem_parse_options(data
, &config
, true))
2202 spin_lock(&sbinfo
->stat_lock
);
2203 blocks
= sbinfo
->max_blocks
- sbinfo
->free_blocks
;
2204 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2205 if (config
.max_blocks
< blocks
)
2207 if (config
.max_inodes
< inodes
)
2210 * Those tests also disallow limited->unlimited while any are in
2211 * use, so i_blocks will always be zero when max_blocks is zero;
2212 * but we must separately disallow unlimited->limited, because
2213 * in that case we have no record of how much is already in use.
2215 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2217 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2221 sbinfo
->max_blocks
= config
.max_blocks
;
2222 sbinfo
->free_blocks
= config
.max_blocks
- blocks
;
2223 sbinfo
->max_inodes
= config
.max_inodes
;
2224 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2226 mpol_put(sbinfo
->mpol
);
2227 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2229 spin_unlock(&sbinfo
->stat_lock
);
2233 static int shmem_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
2235 struct shmem_sb_info
*sbinfo
= SHMEM_SB(vfs
->mnt_sb
);
2237 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2238 seq_printf(seq
, ",size=%luk",
2239 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2240 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2241 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2242 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2243 seq_printf(seq
, ",mode=%03o", sbinfo
->mode
);
2244 if (sbinfo
->uid
!= 0)
2245 seq_printf(seq
, ",uid=%u", sbinfo
->uid
);
2246 if (sbinfo
->gid
!= 0)
2247 seq_printf(seq
, ",gid=%u", sbinfo
->gid
);
2248 shmem_show_mpol(seq
, sbinfo
->mpol
);
2251 #endif /* CONFIG_TMPFS */
2253 static void shmem_put_super(struct super_block
*sb
)
2255 kfree(sb
->s_fs_info
);
2256 sb
->s_fs_info
= NULL
;
2259 static int shmem_fill_super(struct super_block
*sb
,
2260 void *data
, int silent
)
2262 struct inode
*inode
;
2263 struct dentry
*root
;
2264 struct shmem_sb_info
*sbinfo
;
2267 /* Round up to L1_CACHE_BYTES to resist false sharing */
2268 sbinfo
= kmalloc(max((int)sizeof(struct shmem_sb_info
),
2269 L1_CACHE_BYTES
), GFP_KERNEL
);
2273 sbinfo
->max_blocks
= 0;
2274 sbinfo
->max_inodes
= 0;
2275 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2276 sbinfo
->uid
= current
->fsuid
;
2277 sbinfo
->gid
= current
->fsgid
;
2278 sbinfo
->mpol
= NULL
;
2279 sb
->s_fs_info
= sbinfo
;
2283 * Per default we only allow half of the physical ram per
2284 * tmpfs instance, limiting inodes to one per page of lowmem;
2285 * but the internal instance is left unlimited.
2287 if (!(sb
->s_flags
& MS_NOUSER
)) {
2288 sbinfo
->max_blocks
= shmem_default_max_blocks();
2289 sbinfo
->max_inodes
= shmem_default_max_inodes();
2290 if (shmem_parse_options(data
, sbinfo
, false)) {
2295 sb
->s_export_op
= &shmem_export_ops
;
2297 sb
->s_flags
|= MS_NOUSER
;
2300 spin_lock_init(&sbinfo
->stat_lock
);
2301 sbinfo
->free_blocks
= sbinfo
->max_blocks
;
2302 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2304 sb
->s_maxbytes
= SHMEM_MAX_BYTES
;
2305 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2306 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2307 sb
->s_magic
= TMPFS_MAGIC
;
2308 sb
->s_op
= &shmem_ops
;
2309 sb
->s_time_gran
= 1;
2310 #ifdef CONFIG_TMPFS_POSIX_ACL
2311 sb
->s_xattr
= shmem_xattr_handlers
;
2312 sb
->s_flags
|= MS_POSIXACL
;
2315 inode
= shmem_get_inode(sb
, S_IFDIR
| sbinfo
->mode
, 0);
2318 inode
->i_uid
= sbinfo
->uid
;
2319 inode
->i_gid
= sbinfo
->gid
;
2320 root
= d_alloc_root(inode
);
2329 shmem_put_super(sb
);
2333 static struct kmem_cache
*shmem_inode_cachep
;
2335 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2337 struct shmem_inode_info
*p
;
2338 p
= (struct shmem_inode_info
*)kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2341 return &p
->vfs_inode
;
2344 static void shmem_destroy_inode(struct inode
*inode
)
2346 if ((inode
->i_mode
& S_IFMT
) == S_IFREG
) {
2347 /* only struct inode is valid if it's an inline symlink */
2348 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2350 shmem_acl_destroy_inode(inode
);
2351 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2354 static void init_once(void *foo
)
2356 struct shmem_inode_info
*p
= (struct shmem_inode_info
*) foo
;
2358 inode_init_once(&p
->vfs_inode
);
2359 #ifdef CONFIG_TMPFS_POSIX_ACL
2361 p
->i_default_acl
= NULL
;
2365 static int init_inodecache(void)
2367 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2368 sizeof(struct shmem_inode_info
),
2369 0, SLAB_PANIC
, init_once
);
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 .write_begin
= shmem_write_begin
,
2384 .write_end
= shmem_write_end
,
2386 .migratepage
= migrate_page
,
2389 static const struct file_operations shmem_file_operations
= {
2392 .llseek
= generic_file_llseek
,
2393 .read
= do_sync_read
,
2394 .write
= do_sync_write
,
2395 .aio_read
= shmem_file_aio_read
,
2396 .aio_write
= generic_file_aio_write
,
2397 .fsync
= simple_sync_file
,
2398 .splice_read
= generic_file_splice_read
,
2399 .splice_write
= generic_file_splice_write
,
2403 static const struct inode_operations shmem_inode_operations
= {
2404 .truncate
= shmem_truncate
,
2405 .setattr
= shmem_notify_change
,
2406 .truncate_range
= shmem_truncate_range
,
2407 #ifdef CONFIG_TMPFS_POSIX_ACL
2408 .setxattr
= generic_setxattr
,
2409 .getxattr
= generic_getxattr
,
2410 .listxattr
= generic_listxattr
,
2411 .removexattr
= generic_removexattr
,
2412 .permission
= shmem_permission
,
2417 static const struct inode_operations shmem_dir_inode_operations
= {
2419 .create
= shmem_create
,
2420 .lookup
= simple_lookup
,
2422 .unlink
= shmem_unlink
,
2423 .symlink
= shmem_symlink
,
2424 .mkdir
= shmem_mkdir
,
2425 .rmdir
= shmem_rmdir
,
2426 .mknod
= shmem_mknod
,
2427 .rename
= shmem_rename
,
2429 #ifdef CONFIG_TMPFS_POSIX_ACL
2430 .setattr
= shmem_notify_change
,
2431 .setxattr
= generic_setxattr
,
2432 .getxattr
= generic_getxattr
,
2433 .listxattr
= generic_listxattr
,
2434 .removexattr
= generic_removexattr
,
2435 .permission
= shmem_permission
,
2439 static const struct inode_operations shmem_special_inode_operations
= {
2440 #ifdef CONFIG_TMPFS_POSIX_ACL
2441 .setattr
= shmem_notify_change
,
2442 .setxattr
= generic_setxattr
,
2443 .getxattr
= generic_getxattr
,
2444 .listxattr
= generic_listxattr
,
2445 .removexattr
= generic_removexattr
,
2446 .permission
= shmem_permission
,
2450 static const struct super_operations shmem_ops
= {
2451 .alloc_inode
= shmem_alloc_inode
,
2452 .destroy_inode
= shmem_destroy_inode
,
2454 .statfs
= shmem_statfs
,
2455 .remount_fs
= shmem_remount_fs
,
2456 .show_options
= shmem_show_options
,
2458 .delete_inode
= shmem_delete_inode
,
2459 .drop_inode
= generic_delete_inode
,
2460 .put_super
= shmem_put_super
,
2463 static struct vm_operations_struct shmem_vm_ops
= {
2464 .fault
= shmem_fault
,
2466 .set_policy
= shmem_set_policy
,
2467 .get_policy
= shmem_get_policy
,
2472 static int shmem_get_sb(struct file_system_type
*fs_type
,
2473 int flags
, const char *dev_name
, void *data
, struct vfsmount
*mnt
)
2475 return get_sb_nodev(fs_type
, flags
, data
, shmem_fill_super
, mnt
);
2478 static struct file_system_type tmpfs_fs_type
= {
2479 .owner
= THIS_MODULE
,
2481 .get_sb
= shmem_get_sb
,
2482 .kill_sb
= kill_litter_super
,
2484 static struct vfsmount
*shm_mnt
;
2486 static int __init
init_tmpfs(void)
2490 error
= bdi_init(&shmem_backing_dev_info
);
2494 error
= init_inodecache();
2498 error
= register_filesystem(&tmpfs_fs_type
);
2500 printk(KERN_ERR
"Could not register tmpfs\n");
2504 shm_mnt
= vfs_kern_mount(&tmpfs_fs_type
, MS_NOUSER
,
2505 tmpfs_fs_type
.name
, NULL
);
2506 if (IS_ERR(shm_mnt
)) {
2507 error
= PTR_ERR(shm_mnt
);
2508 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2514 unregister_filesystem(&tmpfs_fs_type
);
2516 destroy_inodecache();
2518 bdi_destroy(&shmem_backing_dev_info
);
2520 shm_mnt
= ERR_PTR(error
);
2523 module_init(init_tmpfs
)
2526 * shmem_file_setup - get an unlinked file living in tmpfs
2527 * @name: name for dentry (to be seen in /proc/<pid>/maps
2528 * @size: size to be set for the file
2531 struct file
*shmem_file_setup(char *name
, loff_t size
, unsigned long flags
)
2535 struct inode
*inode
;
2536 struct dentry
*dentry
, *root
;
2539 if (IS_ERR(shm_mnt
))
2540 return (void *)shm_mnt
;
2542 if (size
< 0 || size
> SHMEM_MAX_BYTES
)
2543 return ERR_PTR(-EINVAL
);
2545 if (shmem_acct_size(flags
, size
))
2546 return ERR_PTR(-ENOMEM
);
2550 this.len
= strlen(name
);
2551 this.hash
= 0; /* will go */
2552 root
= shm_mnt
->mnt_root
;
2553 dentry
= d_alloc(root
, &this);
2558 file
= get_empty_filp();
2563 inode
= shmem_get_inode(root
->d_sb
, S_IFREG
| S_IRWXUGO
, 0);
2567 SHMEM_I(inode
)->flags
= flags
& VM_ACCOUNT
;
2568 d_instantiate(dentry
, inode
);
2569 inode
->i_size
= size
;
2570 inode
->i_nlink
= 0; /* It is unlinked */
2571 init_file(file
, shm_mnt
, dentry
, FMODE_WRITE
| FMODE_READ
,
2572 &shmem_file_operations
);
2580 shmem_unacct_size(flags
, size
);
2581 return ERR_PTR(error
);
2585 * shmem_zero_setup - setup a shared anonymous mapping
2586 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2588 int shmem_zero_setup(struct vm_area_struct
*vma
)
2591 loff_t size
= vma
->vm_end
- vma
->vm_start
;
2593 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
2595 return PTR_ERR(file
);
2599 vma
->vm_file
= file
;
2600 vma
->vm_ops
= &shmem_vm_ops
;