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/percpu_counter.h>
32 #include <linux/swap.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/posix_acl.h>
46 #include <linux/generic_acl.h>
47 #include <linux/mman.h>
48 #include <linux/string.h>
49 #include <linux/slab.h>
50 #include <linux/backing-dev.h>
51 #include <linux/shmem_fs.h>
52 #include <linux/writeback.h>
53 #include <linux/blkdev.h>
54 #include <linux/splice.h>
55 #include <linux/security.h>
56 #include <linux/swapops.h>
57 #include <linux/mempolicy.h>
58 #include <linux/namei.h>
59 #include <linux/ctype.h>
60 #include <linux/migrate.h>
61 #include <linux/highmem.h>
62 #include <linux/seq_file.h>
63 #include <linux/magic.h>
65 #include <asm/uaccess.h>
66 #include <asm/div64.h>
67 #include <asm/pgtable.h>
70 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
71 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
73 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
74 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
75 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
76 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
78 * We use / and * instead of shifts in the definitions below, so that the swap
79 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
81 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
82 #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
84 #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
85 #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
87 #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
88 #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
90 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
91 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
93 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
94 #define SHMEM_PAGEIN VM_READ
95 #define SHMEM_TRUNCATE VM_WRITE
97 /* Definition to limit shmem_truncate's steps between cond_rescheds */
98 #define LATENCY_LIMIT 64
100 /* Pretend that each entry is of this size in directory's i_size */
101 #define BOGO_DIRENT_SIZE 20
104 struct list_head list
; /* anchored by shmem_inode_info->xattr_list */
105 char *name
; /* xattr name */
110 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
112 SGP_READ
, /* don't exceed i_size, don't allocate page */
113 SGP_CACHE
, /* don't exceed i_size, may allocate page */
114 SGP_DIRTY
, /* like SGP_CACHE, but set new page dirty */
115 SGP_WRITE
, /* may exceed i_size, may allocate page */
119 static unsigned long shmem_default_max_blocks(void)
121 return totalram_pages
/ 2;
124 static unsigned long shmem_default_max_inodes(void)
126 return min(totalram_pages
- totalhigh_pages
, totalram_pages
/ 2);
130 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
131 struct page
**pagep
, enum sgp_type sgp
, int *type
);
133 static inline struct page
*shmem_dir_alloc(gfp_t gfp_mask
)
136 * The above definition of ENTRIES_PER_PAGE, and the use of
137 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
138 * might be reconsidered if it ever diverges from PAGE_SIZE.
140 * Mobility flags are masked out as swap vectors cannot move
142 return alloc_pages((gfp_mask
& ~GFP_MOVABLE_MASK
) | __GFP_ZERO
,
143 PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
146 static inline void shmem_dir_free(struct page
*page
)
148 __free_pages(page
, PAGE_CACHE_SHIFT
-PAGE_SHIFT
);
151 static struct page
**shmem_dir_map(struct page
*page
)
153 return (struct page
**)kmap_atomic(page
, KM_USER0
);
156 static inline void shmem_dir_unmap(struct page
**dir
)
158 kunmap_atomic(dir
, KM_USER0
);
161 static swp_entry_t
*shmem_swp_map(struct page
*page
)
163 return (swp_entry_t
*)kmap_atomic(page
, KM_USER1
);
166 static inline void shmem_swp_balance_unmap(void)
169 * When passing a pointer to an i_direct entry, to code which
170 * also handles indirect entries and so will shmem_swp_unmap,
171 * we must arrange for the preempt count to remain in balance.
172 * What kmap_atomic of a lowmem page does depends on config
173 * and architecture, so pretend to kmap_atomic some lowmem page.
175 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1
);
178 static inline void shmem_swp_unmap(swp_entry_t
*entry
)
180 kunmap_atomic(entry
, KM_USER1
);
183 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
185 return sb
->s_fs_info
;
189 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
190 * for shared memory and for shared anonymous (/dev/zero) mappings
191 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
192 * consistent with the pre-accounting of private mappings ...
194 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
196 return (flags
& VM_NORESERVE
) ?
197 0 : security_vm_enough_memory_kern(VM_ACCT(size
));
200 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
202 if (!(flags
& VM_NORESERVE
))
203 vm_unacct_memory(VM_ACCT(size
));
207 * ... whereas tmpfs objects are accounted incrementally as
208 * pages are allocated, in order to allow huge sparse files.
209 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
210 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
212 static inline int shmem_acct_block(unsigned long flags
)
214 return (flags
& VM_NORESERVE
) ?
215 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE
)) : 0;
218 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
220 if (flags
& VM_NORESERVE
)
221 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
224 static const struct super_operations shmem_ops
;
225 static const struct address_space_operations shmem_aops
;
226 static const struct file_operations shmem_file_operations
;
227 static const struct inode_operations shmem_inode_operations
;
228 static const struct inode_operations shmem_dir_inode_operations
;
229 static const struct inode_operations shmem_special_inode_operations
;
230 static const struct vm_operations_struct shmem_vm_ops
;
232 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
233 .ra_pages
= 0, /* No readahead */
234 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
| BDI_CAP_SWAP_BACKED
,
237 static LIST_HEAD(shmem_swaplist
);
238 static DEFINE_MUTEX(shmem_swaplist_mutex
);
240 static void shmem_free_blocks(struct inode
*inode
, long pages
)
242 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
243 if (sbinfo
->max_blocks
) {
244 percpu_counter_add(&sbinfo
->used_blocks
, -pages
);
245 inode
->i_blocks
-= pages
*BLOCKS_PER_PAGE
;
249 static int shmem_reserve_inode(struct super_block
*sb
)
251 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
252 if (sbinfo
->max_inodes
) {
253 spin_lock(&sbinfo
->stat_lock
);
254 if (!sbinfo
->free_inodes
) {
255 spin_unlock(&sbinfo
->stat_lock
);
258 sbinfo
->free_inodes
--;
259 spin_unlock(&sbinfo
->stat_lock
);
264 static void shmem_free_inode(struct super_block
*sb
)
266 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
267 if (sbinfo
->max_inodes
) {
268 spin_lock(&sbinfo
->stat_lock
);
269 sbinfo
->free_inodes
++;
270 spin_unlock(&sbinfo
->stat_lock
);
275 * shmem_recalc_inode - recalculate the size of an inode
276 * @inode: inode to recalc
278 * We have to calculate the free blocks since the mm can drop
279 * undirtied hole pages behind our back.
281 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
282 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
284 * It has to be called with the spinlock held.
286 static void shmem_recalc_inode(struct inode
*inode
)
288 struct shmem_inode_info
*info
= SHMEM_I(inode
);
291 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
293 info
->alloced
-= freed
;
294 shmem_unacct_blocks(info
->flags
, freed
);
295 shmem_free_blocks(inode
, freed
);
300 * shmem_swp_entry - find the swap vector position in the info structure
301 * @info: info structure for the inode
302 * @index: index of the page to find
303 * @page: optional page to add to the structure. Has to be preset to
306 * If there is no space allocated yet it will return NULL when
307 * page is NULL, else it will use the page for the needed block,
308 * setting it to NULL on return to indicate that it has been used.
310 * The swap vector is organized the following way:
312 * There are SHMEM_NR_DIRECT entries directly stored in the
313 * shmem_inode_info structure. So small files do not need an addional
316 * For pages with index > SHMEM_NR_DIRECT there is the pointer
317 * i_indirect which points to a page which holds in the first half
318 * doubly indirect blocks, in the second half triple indirect blocks:
320 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
321 * following layout (for SHMEM_NR_DIRECT == 16):
323 * i_indirect -> dir --> 16-19
336 static swp_entry_t
*shmem_swp_entry(struct shmem_inode_info
*info
, unsigned long index
, struct page
**page
)
338 unsigned long offset
;
342 if (index
< SHMEM_NR_DIRECT
) {
343 shmem_swp_balance_unmap();
344 return info
->i_direct
+index
;
346 if (!info
->i_indirect
) {
348 info
->i_indirect
= *page
;
351 return NULL
; /* need another page */
354 index
-= SHMEM_NR_DIRECT
;
355 offset
= index
% ENTRIES_PER_PAGE
;
356 index
/= ENTRIES_PER_PAGE
;
357 dir
= shmem_dir_map(info
->i_indirect
);
359 if (index
>= ENTRIES_PER_PAGE
/2) {
360 index
-= ENTRIES_PER_PAGE
/2;
361 dir
+= ENTRIES_PER_PAGE
/2 + index
/ENTRIES_PER_PAGE
;
362 index
%= ENTRIES_PER_PAGE
;
369 shmem_dir_unmap(dir
);
370 return NULL
; /* need another page */
372 shmem_dir_unmap(dir
);
373 dir
= shmem_dir_map(subdir
);
379 if (!page
|| !(subdir
= *page
)) {
380 shmem_dir_unmap(dir
);
381 return NULL
; /* need a page */
386 shmem_dir_unmap(dir
);
387 return shmem_swp_map(subdir
) + offset
;
390 static void shmem_swp_set(struct shmem_inode_info
*info
, swp_entry_t
*entry
, unsigned long value
)
392 long incdec
= value
? 1: -1;
395 info
->swapped
+= incdec
;
396 if ((unsigned long)(entry
- info
->i_direct
) >= SHMEM_NR_DIRECT
) {
397 struct page
*page
= kmap_atomic_to_page(entry
);
398 set_page_private(page
, page_private(page
) + incdec
);
403 * shmem_swp_alloc - get the position of the swap entry for the page.
404 * @info: info structure for the inode
405 * @index: index of the page to find
406 * @sgp: check and recheck i_size? skip allocation?
408 * If the entry does not exist, allocate it.
410 static swp_entry_t
*shmem_swp_alloc(struct shmem_inode_info
*info
, unsigned long index
, enum sgp_type sgp
)
412 struct inode
*inode
= &info
->vfs_inode
;
413 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
414 struct page
*page
= NULL
;
417 if (sgp
!= SGP_WRITE
&&
418 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
419 return ERR_PTR(-EINVAL
);
421 while (!(entry
= shmem_swp_entry(info
, index
, &page
))) {
423 return shmem_swp_map(ZERO_PAGE(0));
425 * Test used_blocks against 1 less max_blocks, since we have 1 data
426 * page (and perhaps indirect index pages) yet to allocate:
427 * a waste to allocate index if we cannot allocate data.
429 if (sbinfo
->max_blocks
) {
430 if (percpu_counter_compare(&sbinfo
->used_blocks
,
431 sbinfo
->max_blocks
- 1) >= 0)
432 return ERR_PTR(-ENOSPC
);
433 percpu_counter_inc(&sbinfo
->used_blocks
);
434 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
437 spin_unlock(&info
->lock
);
438 page
= shmem_dir_alloc(mapping_gfp_mask(inode
->i_mapping
));
439 spin_lock(&info
->lock
);
442 shmem_free_blocks(inode
, 1);
443 return ERR_PTR(-ENOMEM
);
445 if (sgp
!= SGP_WRITE
&&
446 ((loff_t
) index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
447 entry
= ERR_PTR(-EINVAL
);
450 if (info
->next_index
<= index
)
451 info
->next_index
= index
+ 1;
454 /* another task gave its page, or truncated the file */
455 shmem_free_blocks(inode
, 1);
456 shmem_dir_free(page
);
458 if (info
->next_index
<= index
&& !IS_ERR(entry
))
459 info
->next_index
= index
+ 1;
464 * shmem_free_swp - free some swap entries in a directory
465 * @dir: pointer to the directory
466 * @edir: pointer after last entry of the directory
467 * @punch_lock: pointer to spinlock when needed for the holepunch case
469 static int shmem_free_swp(swp_entry_t
*dir
, swp_entry_t
*edir
,
470 spinlock_t
*punch_lock
)
472 spinlock_t
*punch_unlock
= NULL
;
476 for (ptr
= dir
; ptr
< edir
; ptr
++) {
478 if (unlikely(punch_lock
)) {
479 punch_unlock
= punch_lock
;
481 spin_lock(punch_unlock
);
485 free_swap_and_cache(*ptr
);
486 *ptr
= (swp_entry_t
){0};
491 spin_unlock(punch_unlock
);
495 static int shmem_map_and_free_swp(struct page
*subdir
, int offset
,
496 int limit
, struct page
***dir
, spinlock_t
*punch_lock
)
501 ptr
= shmem_swp_map(subdir
);
502 for (; offset
< limit
; offset
+= LATENCY_LIMIT
) {
503 int size
= limit
- offset
;
504 if (size
> LATENCY_LIMIT
)
505 size
= LATENCY_LIMIT
;
506 freed
+= shmem_free_swp(ptr
+offset
, ptr
+offset
+size
,
508 if (need_resched()) {
509 shmem_swp_unmap(ptr
);
511 shmem_dir_unmap(*dir
);
515 ptr
= shmem_swp_map(subdir
);
518 shmem_swp_unmap(ptr
);
522 static void shmem_free_pages(struct list_head
*next
)
528 page
= container_of(next
, struct page
, lru
);
530 shmem_dir_free(page
);
532 if (freed
>= LATENCY_LIMIT
) {
539 void shmem_truncate_range(struct inode
*inode
, loff_t start
, loff_t end
)
541 struct shmem_inode_info
*info
= SHMEM_I(inode
);
546 unsigned long diroff
;
552 LIST_HEAD(pages_to_free
);
553 long nr_pages_to_free
= 0;
554 long nr_swaps_freed
= 0;
558 spinlock_t
*needs_lock
;
559 spinlock_t
*punch_lock
;
560 unsigned long upper_limit
;
562 truncate_inode_pages_range(inode
->i_mapping
, start
, end
);
564 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
565 idx
= (start
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
566 if (idx
>= info
->next_index
)
569 spin_lock(&info
->lock
);
570 info
->flags
|= SHMEM_TRUNCATE
;
571 if (likely(end
== (loff_t
) -1)) {
572 limit
= info
->next_index
;
573 upper_limit
= SHMEM_MAX_INDEX
;
574 info
->next_index
= idx
;
578 if (end
+ 1 >= inode
->i_size
) { /* we may free a little more */
579 limit
= (inode
->i_size
+ PAGE_CACHE_SIZE
- 1) >>
581 upper_limit
= SHMEM_MAX_INDEX
;
583 limit
= (end
+ 1) >> PAGE_CACHE_SHIFT
;
586 needs_lock
= &info
->lock
;
590 topdir
= info
->i_indirect
;
591 if (topdir
&& idx
<= SHMEM_NR_DIRECT
&& !punch_hole
) {
592 info
->i_indirect
= NULL
;
594 list_add(&topdir
->lru
, &pages_to_free
);
596 spin_unlock(&info
->lock
);
598 if (info
->swapped
&& idx
< SHMEM_NR_DIRECT
) {
599 ptr
= info
->i_direct
;
601 if (size
> SHMEM_NR_DIRECT
)
602 size
= SHMEM_NR_DIRECT
;
603 nr_swaps_freed
= shmem_free_swp(ptr
+idx
, ptr
+size
, needs_lock
);
607 * If there are no indirect blocks or we are punching a hole
608 * below indirect blocks, nothing to be done.
610 if (!topdir
|| limit
<= SHMEM_NR_DIRECT
)
614 * The truncation case has already dropped info->lock, and we're safe
615 * because i_size and next_index have already been lowered, preventing
616 * access beyond. But in the punch_hole case, we still need to take
617 * the lock when updating the swap directory, because there might be
618 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
619 * shmem_writepage. However, whenever we find we can remove a whole
620 * directory page (not at the misaligned start or end of the range),
621 * we first NULLify its pointer in the level above, and then have no
622 * need to take the lock when updating its contents: needs_lock and
623 * punch_lock (either pointing to info->lock or NULL) manage this.
626 upper_limit
-= SHMEM_NR_DIRECT
;
627 limit
-= SHMEM_NR_DIRECT
;
628 idx
= (idx
> SHMEM_NR_DIRECT
)? (idx
- SHMEM_NR_DIRECT
): 0;
629 offset
= idx
% ENTRIES_PER_PAGE
;
632 dir
= shmem_dir_map(topdir
);
633 stage
= ENTRIES_PER_PAGEPAGE
/2;
634 if (idx
< ENTRIES_PER_PAGEPAGE
/2) {
636 diroff
= idx
/ENTRIES_PER_PAGE
;
638 dir
+= ENTRIES_PER_PAGE
/2;
639 dir
+= (idx
- ENTRIES_PER_PAGEPAGE
/2)/ENTRIES_PER_PAGEPAGE
;
641 stage
+= ENTRIES_PER_PAGEPAGE
;
644 diroff
= ((idx
- ENTRIES_PER_PAGEPAGE
/2) %
645 ENTRIES_PER_PAGEPAGE
) / ENTRIES_PER_PAGE
;
646 if (!diroff
&& !offset
&& upper_limit
>= stage
) {
648 spin_lock(needs_lock
);
650 spin_unlock(needs_lock
);
655 list_add(&middir
->lru
, &pages_to_free
);
657 shmem_dir_unmap(dir
);
658 dir
= shmem_dir_map(middir
);
666 for (; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, diroff
++) {
667 if (unlikely(idx
== stage
)) {
668 shmem_dir_unmap(dir
);
669 dir
= shmem_dir_map(topdir
) +
670 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
673 idx
+= ENTRIES_PER_PAGEPAGE
;
677 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
680 needs_lock
= &info
->lock
;
681 if (upper_limit
>= stage
) {
683 spin_lock(needs_lock
);
685 spin_unlock(needs_lock
);
690 list_add(&middir
->lru
, &pages_to_free
);
692 shmem_dir_unmap(dir
);
694 dir
= shmem_dir_map(middir
);
697 punch_lock
= needs_lock
;
698 subdir
= dir
[diroff
];
699 if (subdir
&& !offset
&& upper_limit
-idx
>= ENTRIES_PER_PAGE
) {
701 spin_lock(needs_lock
);
703 spin_unlock(needs_lock
);
708 list_add(&subdir
->lru
, &pages_to_free
);
710 if (subdir
&& page_private(subdir
) /* has swap entries */) {
712 if (size
> ENTRIES_PER_PAGE
)
713 size
= ENTRIES_PER_PAGE
;
714 freed
= shmem_map_and_free_swp(subdir
,
715 offset
, size
, &dir
, punch_lock
);
717 dir
= shmem_dir_map(middir
);
718 nr_swaps_freed
+= freed
;
719 if (offset
|| punch_lock
) {
720 spin_lock(&info
->lock
);
721 set_page_private(subdir
,
722 page_private(subdir
) - freed
);
723 spin_unlock(&info
->lock
);
725 BUG_ON(page_private(subdir
) != freed
);
730 shmem_dir_unmap(dir
);
732 if (inode
->i_mapping
->nrpages
&& (info
->flags
& SHMEM_PAGEIN
)) {
734 * Call truncate_inode_pages again: racing shmem_unuse_inode
735 * may have swizzled a page in from swap since
736 * truncate_pagecache or generic_delete_inode did it, before we
737 * lowered next_index. Also, though shmem_getpage checks
738 * i_size before adding to cache, no recheck after: so fix the
739 * narrow window there too.
741 truncate_inode_pages_range(inode
->i_mapping
, start
, end
);
744 spin_lock(&info
->lock
);
745 info
->flags
&= ~SHMEM_TRUNCATE
;
746 info
->swapped
-= nr_swaps_freed
;
747 if (nr_pages_to_free
)
748 shmem_free_blocks(inode
, nr_pages_to_free
);
749 shmem_recalc_inode(inode
);
750 spin_unlock(&info
->lock
);
753 * Empty swap vector directory pages to be freed?
755 if (!list_empty(&pages_to_free
)) {
756 pages_to_free
.prev
->next
= NULL
;
757 shmem_free_pages(pages_to_free
.next
);
760 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
762 static int shmem_setattr(struct dentry
*dentry
, struct iattr
*attr
)
764 struct inode
*inode
= dentry
->d_inode
;
767 error
= inode_change_ok(inode
, attr
);
771 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
772 loff_t oldsize
= inode
->i_size
;
773 loff_t newsize
= attr
->ia_size
;
774 struct page
*page
= NULL
;
776 if (newsize
< oldsize
) {
778 * If truncating down to a partial page, then
779 * if that page is already allocated, hold it
780 * in memory until the truncation is over, so
781 * truncate_partial_page cannot miss it were
782 * it assigned to swap.
784 if (newsize
& (PAGE_CACHE_SIZE
-1)) {
785 (void) shmem_getpage(inode
,
786 newsize
>> PAGE_CACHE_SHIFT
,
787 &page
, SGP_READ
, NULL
);
792 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
793 * detect if any pages might have been added to cache
794 * after truncate_inode_pages. But we needn't bother
795 * if it's being fully truncated to zero-length: the
796 * nrpages check is efficient enough in that case.
799 struct shmem_inode_info
*info
= SHMEM_I(inode
);
800 spin_lock(&info
->lock
);
801 info
->flags
&= ~SHMEM_PAGEIN
;
802 spin_unlock(&info
->lock
);
805 if (newsize
!= oldsize
) {
806 i_size_write(inode
, newsize
);
807 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
809 if (newsize
< oldsize
) {
810 loff_t holebegin
= round_up(newsize
, PAGE_SIZE
);
811 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
812 shmem_truncate_range(inode
, newsize
, (loff_t
)-1);
813 /* unmap again to remove racily COWed private pages */
814 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
817 page_cache_release(page
);
820 setattr_copy(inode
, attr
);
821 #ifdef CONFIG_TMPFS_POSIX_ACL
822 if (attr
->ia_valid
& ATTR_MODE
)
823 error
= generic_acl_chmod(inode
);
828 static void shmem_evict_inode(struct inode
*inode
)
830 struct shmem_inode_info
*info
= SHMEM_I(inode
);
831 struct shmem_xattr
*xattr
, *nxattr
;
833 if (inode
->i_mapping
->a_ops
== &shmem_aops
) {
834 shmem_unacct_size(info
->flags
, inode
->i_size
);
836 shmem_truncate_range(inode
, 0, (loff_t
)-1);
837 if (!list_empty(&info
->swaplist
)) {
838 mutex_lock(&shmem_swaplist_mutex
);
839 list_del_init(&info
->swaplist
);
840 mutex_unlock(&shmem_swaplist_mutex
);
844 list_for_each_entry_safe(xattr
, nxattr
, &info
->xattr_list
, list
) {
848 BUG_ON(inode
->i_blocks
);
849 shmem_free_inode(inode
->i_sb
);
850 end_writeback(inode
);
853 static inline int shmem_find_swp(swp_entry_t entry
, swp_entry_t
*dir
, swp_entry_t
*edir
)
857 for (ptr
= dir
; ptr
< edir
; ptr
++) {
858 if (ptr
->val
== entry
.val
)
864 static int shmem_unuse_inode(struct shmem_inode_info
*info
, swp_entry_t entry
, struct page
*page
)
866 struct address_space
*mapping
;
878 ptr
= info
->i_direct
;
879 spin_lock(&info
->lock
);
880 if (!info
->swapped
) {
881 list_del_init(&info
->swaplist
);
884 limit
= info
->next_index
;
886 if (size
> SHMEM_NR_DIRECT
)
887 size
= SHMEM_NR_DIRECT
;
888 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
890 shmem_swp_balance_unmap();
893 if (!info
->i_indirect
)
896 dir
= shmem_dir_map(info
->i_indirect
);
897 stage
= SHMEM_NR_DIRECT
+ ENTRIES_PER_PAGEPAGE
/2;
899 for (idx
= SHMEM_NR_DIRECT
; idx
< limit
; idx
+= ENTRIES_PER_PAGE
, dir
++) {
900 if (unlikely(idx
== stage
)) {
901 shmem_dir_unmap(dir
-1);
902 if (cond_resched_lock(&info
->lock
)) {
903 /* check it has not been truncated */
904 if (limit
> info
->next_index
) {
905 limit
= info
->next_index
;
910 dir
= shmem_dir_map(info
->i_indirect
) +
911 ENTRIES_PER_PAGE
/2 + idx
/ENTRIES_PER_PAGEPAGE
;
914 idx
+= ENTRIES_PER_PAGEPAGE
;
918 stage
= idx
+ ENTRIES_PER_PAGEPAGE
;
920 shmem_dir_unmap(dir
);
921 dir
= shmem_dir_map(subdir
);
924 if (subdir
&& page_private(subdir
)) {
925 ptr
= shmem_swp_map(subdir
);
927 if (size
> ENTRIES_PER_PAGE
)
928 size
= ENTRIES_PER_PAGE
;
929 offset
= shmem_find_swp(entry
, ptr
, ptr
+size
);
930 shmem_swp_unmap(ptr
);
932 shmem_dir_unmap(dir
);
933 ptr
= shmem_swp_map(subdir
);
939 shmem_dir_unmap(dir
-1);
941 spin_unlock(&info
->lock
);
948 * Move _head_ to start search for next from here.
949 * But be careful: shmem_evict_inode checks list_empty without taking
950 * mutex, and there's an instant in list_move_tail when info->swaplist
951 * would appear empty, if it were the only one on shmem_swaplist. We
952 * could avoid doing it if inode NULL; or use this minor optimization.
954 if (shmem_swaplist
.next
!= &info
->swaplist
)
955 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
958 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
959 * but also to hold up shmem_evict_inode(): so inode cannot be freed
960 * beneath us (pagelock doesn't help until the page is in pagecache).
962 mapping
= info
->vfs_inode
.i_mapping
;
963 error
= add_to_page_cache_locked(page
, mapping
, idx
, GFP_NOWAIT
);
964 /* which does mem_cgroup_uncharge_cache_page on error */
966 if (error
== -EEXIST
) {
967 struct page
*filepage
= find_get_page(mapping
, idx
);
971 * There might be a more uptodate page coming down
972 * from a stacked writepage: forget our swappage if so.
974 if (PageUptodate(filepage
))
976 page_cache_release(filepage
);
980 delete_from_swap_cache(page
);
981 set_page_dirty(page
);
982 info
->flags
|= SHMEM_PAGEIN
;
983 shmem_swp_set(info
, ptr
, 0);
985 error
= 1; /* not an error, but entry was found */
987 shmem_swp_unmap(ptr
);
988 spin_unlock(&info
->lock
);
993 * shmem_unuse() search for an eventually swapped out shmem page.
995 int shmem_unuse(swp_entry_t entry
, struct page
*page
)
997 struct list_head
*p
, *next
;
998 struct shmem_inode_info
*info
;
1003 * Charge page using GFP_KERNEL while we can wait, before taking
1004 * the shmem_swaplist_mutex which might hold up shmem_writepage().
1005 * Charged back to the user (not to caller) when swap account is used.
1006 * add_to_page_cache() will be called with GFP_NOWAIT.
1008 error
= mem_cgroup_cache_charge(page
, current
->mm
, GFP_KERNEL
);
1012 * Try to preload while we can wait, to not make a habit of
1013 * draining atomic reserves; but don't latch on to this cpu,
1014 * it's okay if sometimes we get rescheduled after this.
1016 error
= radix_tree_preload(GFP_KERNEL
);
1019 radix_tree_preload_end();
1021 mutex_lock(&shmem_swaplist_mutex
);
1022 list_for_each_safe(p
, next
, &shmem_swaplist
) {
1023 info
= list_entry(p
, struct shmem_inode_info
, swaplist
);
1024 found
= shmem_unuse_inode(info
, entry
, page
);
1029 mutex_unlock(&shmem_swaplist_mutex
);
1033 mem_cgroup_uncharge_cache_page(page
);
1038 page_cache_release(page
);
1043 * Move the page from the page cache to the swap cache.
1045 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
1047 struct shmem_inode_info
*info
;
1048 swp_entry_t
*entry
, swap
;
1049 struct address_space
*mapping
;
1050 unsigned long index
;
1051 struct inode
*inode
;
1053 BUG_ON(!PageLocked(page
));
1054 mapping
= page
->mapping
;
1055 index
= page
->index
;
1056 inode
= mapping
->host
;
1057 info
= SHMEM_I(inode
);
1058 if (info
->flags
& VM_LOCKED
)
1060 if (!total_swap_pages
)
1064 * shmem_backing_dev_info's capabilities prevent regular writeback or
1065 * sync from ever calling shmem_writepage; but a stacking filesystem
1066 * may use the ->writepage of its underlying filesystem, in which case
1067 * tmpfs should write out to swap only in response to memory pressure,
1068 * and not for the writeback threads or sync. However, in those cases,
1069 * we do still want to check if there's a redundant swappage to be
1072 if (wbc
->for_reclaim
)
1073 swap
= get_swap_page();
1078 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1079 * if it's not already there. Do it now because we cannot take
1080 * mutex while holding spinlock, and must do so before the page
1081 * is moved to swap cache, when its pagelock no longer protects
1082 * the inode from eviction. But don't unlock the mutex until
1083 * we've taken the spinlock, because shmem_unuse_inode() will
1084 * prune a !swapped inode from the swaplist under both locks.
1087 mutex_lock(&shmem_swaplist_mutex
);
1088 if (list_empty(&info
->swaplist
))
1089 list_add_tail(&info
->swaplist
, &shmem_swaplist
);
1092 spin_lock(&info
->lock
);
1094 mutex_unlock(&shmem_swaplist_mutex
);
1096 if (index
>= info
->next_index
) {
1097 BUG_ON(!(info
->flags
& SHMEM_TRUNCATE
));
1100 entry
= shmem_swp_entry(info
, index
, NULL
);
1103 * The more uptodate page coming down from a stacked
1104 * writepage should replace our old swappage.
1106 free_swap_and_cache(*entry
);
1107 shmem_swp_set(info
, entry
, 0);
1109 shmem_recalc_inode(inode
);
1111 if (swap
.val
&& add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
1112 delete_from_page_cache(page
);
1113 shmem_swp_set(info
, entry
, swap
.val
);
1114 shmem_swp_unmap(entry
);
1115 swap_shmem_alloc(swap
);
1116 spin_unlock(&info
->lock
);
1117 BUG_ON(page_mapped(page
));
1118 swap_writepage(page
, wbc
);
1122 shmem_swp_unmap(entry
);
1124 spin_unlock(&info
->lock
);
1126 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1127 * clear SWAP_HAS_CACHE flag.
1129 swapcache_free(swap
, NULL
);
1131 set_page_dirty(page
);
1132 if (wbc
->for_reclaim
)
1133 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
1140 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
1144 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
1145 return; /* show nothing */
1147 mpol_to_str(buffer
, sizeof(buffer
), mpol
, 1);
1149 seq_printf(seq
, ",mpol=%s", buffer
);
1152 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
1154 struct mempolicy
*mpol
= NULL
;
1156 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
1157 mpol
= sbinfo
->mpol
;
1159 spin_unlock(&sbinfo
->stat_lock
);
1163 #endif /* CONFIG_TMPFS */
1165 static struct page
*shmem_swapin(swp_entry_t entry
, gfp_t gfp
,
1166 struct shmem_inode_info
*info
, unsigned long idx
)
1168 struct mempolicy mpol
, *spol
;
1169 struct vm_area_struct pvma
;
1172 spol
= mpol_cond_copy(&mpol
,
1173 mpol_shared_policy_lookup(&info
->policy
, idx
));
1175 /* Create a pseudo vma that just contains the policy */
1177 pvma
.vm_pgoff
= idx
;
1179 pvma
.vm_policy
= spol
;
1180 page
= swapin_readahead(entry
, gfp
, &pvma
, 0);
1184 static struct page
*shmem_alloc_page(gfp_t gfp
,
1185 struct shmem_inode_info
*info
, unsigned long idx
)
1187 struct vm_area_struct pvma
;
1189 /* Create a pseudo vma that just contains the policy */
1191 pvma
.vm_pgoff
= idx
;
1193 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, idx
);
1196 * alloc_page_vma() will drop the shared policy reference
1198 return alloc_page_vma(gfp
, &pvma
, 0);
1200 #else /* !CONFIG_NUMA */
1202 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*p
)
1205 #endif /* CONFIG_TMPFS */
1207 static inline struct page
*shmem_swapin(swp_entry_t entry
, gfp_t gfp
,
1208 struct shmem_inode_info
*info
, unsigned long idx
)
1210 return swapin_readahead(entry
, gfp
, NULL
, 0);
1213 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
1214 struct shmem_inode_info
*info
, unsigned long idx
)
1216 return alloc_page(gfp
);
1218 #endif /* CONFIG_NUMA */
1220 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1221 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
1228 * shmem_getpage - either get the page from swap or allocate a new one
1230 * If we allocate a new one we do not mark it dirty. That's up to the
1231 * vm. If we swap it in we mark it dirty since we also free the swap
1232 * entry since a page cannot live in both the swap and page cache
1234 static int shmem_getpage(struct inode
*inode
, unsigned long idx
,
1235 struct page
**pagep
, enum sgp_type sgp
, int *type
)
1237 struct address_space
*mapping
= inode
->i_mapping
;
1238 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1239 struct shmem_sb_info
*sbinfo
;
1240 struct page
*filepage
= *pagep
;
1241 struct page
*swappage
;
1242 struct page
*prealloc_page
= NULL
;
1248 if (idx
>= SHMEM_MAX_INDEX
)
1255 * Normally, filepage is NULL on entry, and either found
1256 * uptodate immediately, or allocated and zeroed, or read
1257 * in under swappage, which is then assigned to filepage.
1258 * But shmem_readpage (required for splice) passes in a locked
1259 * filepage, which may be found not uptodate by other callers
1260 * too, and may need to be copied from the swappage read in.
1264 filepage
= find_lock_page(mapping
, idx
);
1265 if (filepage
&& PageUptodate(filepage
))
1267 gfp
= mapping_gfp_mask(mapping
);
1270 * Try to preload while we can wait, to not make a habit of
1271 * draining atomic reserves; but don't latch on to this cpu.
1273 error
= radix_tree_preload(gfp
& ~__GFP_HIGHMEM
);
1276 radix_tree_preload_end();
1277 if (sgp
!= SGP_READ
&& !prealloc_page
) {
1278 /* We don't care if this fails */
1279 prealloc_page
= shmem_alloc_page(gfp
, info
, idx
);
1280 if (prealloc_page
) {
1281 if (mem_cgroup_cache_charge(prealloc_page
,
1282 current
->mm
, GFP_KERNEL
)) {
1283 page_cache_release(prealloc_page
);
1284 prealloc_page
= NULL
;
1291 spin_lock(&info
->lock
);
1292 shmem_recalc_inode(inode
);
1293 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1294 if (IS_ERR(entry
)) {
1295 spin_unlock(&info
->lock
);
1296 error
= PTR_ERR(entry
);
1302 /* Look it up and read it in.. */
1303 swappage
= lookup_swap_cache(swap
);
1305 shmem_swp_unmap(entry
);
1306 spin_unlock(&info
->lock
);
1307 /* here we actually do the io */
1309 *type
|= VM_FAULT_MAJOR
;
1310 swappage
= shmem_swapin(swap
, gfp
, info
, idx
);
1312 spin_lock(&info
->lock
);
1313 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1315 error
= PTR_ERR(entry
);
1317 if (entry
->val
== swap
.val
)
1319 shmem_swp_unmap(entry
);
1321 spin_unlock(&info
->lock
);
1326 wait_on_page_locked(swappage
);
1327 page_cache_release(swappage
);
1331 /* We have to do this with page locked to prevent races */
1332 if (!trylock_page(swappage
)) {
1333 shmem_swp_unmap(entry
);
1334 spin_unlock(&info
->lock
);
1335 wait_on_page_locked(swappage
);
1336 page_cache_release(swappage
);
1339 if (PageWriteback(swappage
)) {
1340 shmem_swp_unmap(entry
);
1341 spin_unlock(&info
->lock
);
1342 wait_on_page_writeback(swappage
);
1343 unlock_page(swappage
);
1344 page_cache_release(swappage
);
1347 if (!PageUptodate(swappage
)) {
1348 shmem_swp_unmap(entry
);
1349 spin_unlock(&info
->lock
);
1350 unlock_page(swappage
);
1351 page_cache_release(swappage
);
1357 shmem_swp_set(info
, entry
, 0);
1358 shmem_swp_unmap(entry
);
1359 delete_from_swap_cache(swappage
);
1360 spin_unlock(&info
->lock
);
1361 copy_highpage(filepage
, swappage
);
1362 unlock_page(swappage
);
1363 page_cache_release(swappage
);
1364 flush_dcache_page(filepage
);
1365 SetPageUptodate(filepage
);
1366 set_page_dirty(filepage
);
1368 } else if (!(error
= add_to_page_cache_locked(swappage
, mapping
,
1369 idx
, GFP_NOWAIT
))) {
1370 info
->flags
|= SHMEM_PAGEIN
;
1371 shmem_swp_set(info
, entry
, 0);
1372 shmem_swp_unmap(entry
);
1373 delete_from_swap_cache(swappage
);
1374 spin_unlock(&info
->lock
);
1375 filepage
= swappage
;
1376 set_page_dirty(filepage
);
1379 shmem_swp_unmap(entry
);
1380 spin_unlock(&info
->lock
);
1381 if (error
== -ENOMEM
) {
1383 * reclaim from proper memory cgroup and
1384 * call memcg's OOM if needed.
1386 error
= mem_cgroup_shmem_charge_fallback(
1391 unlock_page(swappage
);
1392 page_cache_release(swappage
);
1396 unlock_page(swappage
);
1397 page_cache_release(swappage
);
1400 } else if (sgp
== SGP_READ
&& !filepage
) {
1401 shmem_swp_unmap(entry
);
1402 filepage
= find_get_page(mapping
, idx
);
1404 (!PageUptodate(filepage
) || !trylock_page(filepage
))) {
1405 spin_unlock(&info
->lock
);
1406 wait_on_page_locked(filepage
);
1407 page_cache_release(filepage
);
1411 spin_unlock(&info
->lock
);
1413 shmem_swp_unmap(entry
);
1414 sbinfo
= SHMEM_SB(inode
->i_sb
);
1415 if (sbinfo
->max_blocks
) {
1416 if (percpu_counter_compare(&sbinfo
->used_blocks
,
1417 sbinfo
->max_blocks
) >= 0 ||
1418 shmem_acct_block(info
->flags
))
1420 percpu_counter_inc(&sbinfo
->used_blocks
);
1421 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1422 } else if (shmem_acct_block(info
->flags
))
1428 if (!prealloc_page
) {
1429 spin_unlock(&info
->lock
);
1430 filepage
= shmem_alloc_page(gfp
, info
, idx
);
1432 spin_lock(&info
->lock
);
1433 shmem_unacct_blocks(info
->flags
, 1);
1434 shmem_free_blocks(inode
, 1);
1435 spin_unlock(&info
->lock
);
1439 SetPageSwapBacked(filepage
);
1442 * Precharge page while we can wait, compensate
1445 error
= mem_cgroup_cache_charge(filepage
,
1446 current
->mm
, GFP_KERNEL
);
1448 page_cache_release(filepage
);
1449 spin_lock(&info
->lock
);
1450 shmem_unacct_blocks(info
->flags
, 1);
1451 shmem_free_blocks(inode
, 1);
1452 spin_unlock(&info
->lock
);
1457 spin_lock(&info
->lock
);
1459 filepage
= prealloc_page
;
1460 prealloc_page
= NULL
;
1461 SetPageSwapBacked(filepage
);
1464 entry
= shmem_swp_alloc(info
, idx
, sgp
);
1466 error
= PTR_ERR(entry
);
1469 shmem_swp_unmap(entry
);
1471 ret
= error
|| swap
.val
;
1473 mem_cgroup_uncharge_cache_page(filepage
);
1475 ret
= add_to_page_cache_lru(filepage
, mapping
,
1478 * At add_to_page_cache_lru() failure, uncharge will
1479 * be done automatically.
1482 shmem_unacct_blocks(info
->flags
, 1);
1483 shmem_free_blocks(inode
, 1);
1484 spin_unlock(&info
->lock
);
1485 page_cache_release(filepage
);
1491 info
->flags
|= SHMEM_PAGEIN
;
1495 spin_unlock(&info
->lock
);
1496 clear_highpage(filepage
);
1497 flush_dcache_page(filepage
);
1498 SetPageUptodate(filepage
);
1499 if (sgp
== SGP_DIRTY
)
1500 set_page_dirty(filepage
);
1509 * Perhaps the page was brought in from swap between find_lock_page
1510 * and taking info->lock? We allow for that at add_to_page_cache_lru,
1511 * but must also avoid reporting a spurious ENOSPC while working on a
1512 * full tmpfs. (When filepage has been passed in to shmem_getpage, it
1513 * is already in page cache, which prevents this race from occurring.)
1516 struct page
*page
= find_get_page(mapping
, idx
);
1518 spin_unlock(&info
->lock
);
1519 page_cache_release(page
);
1523 spin_unlock(&info
->lock
);
1526 if (*pagep
!= filepage
) {
1527 unlock_page(filepage
);
1528 page_cache_release(filepage
);
1531 if (prealloc_page
) {
1532 mem_cgroup_uncharge_cache_page(prealloc_page
);
1533 page_cache_release(prealloc_page
);
1538 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1540 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1544 if (((loff_t
)vmf
->pgoff
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
1545 return VM_FAULT_SIGBUS
;
1547 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1549 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1550 if (ret
& VM_FAULT_MAJOR
) {
1551 count_vm_event(PGMAJFAULT
);
1552 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1554 return ret
| VM_FAULT_LOCKED
;
1558 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*new)
1560 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1561 return mpol_set_shared_policy(&SHMEM_I(i
)->policy
, vma
, new);
1564 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1567 struct inode
*i
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1570 idx
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1571 return mpol_shared_policy_lookup(&SHMEM_I(i
)->policy
, idx
);
1575 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1577 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1578 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1579 int retval
= -ENOMEM
;
1581 spin_lock(&info
->lock
);
1582 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1583 if (!user_shm_lock(inode
->i_size
, user
))
1585 info
->flags
|= VM_LOCKED
;
1586 mapping_set_unevictable(file
->f_mapping
);
1588 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1589 user_shm_unlock(inode
->i_size
, user
);
1590 info
->flags
&= ~VM_LOCKED
;
1591 mapping_clear_unevictable(file
->f_mapping
);
1592 scan_mapping_unevictable_pages(file
->f_mapping
);
1597 spin_unlock(&info
->lock
);
1601 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1603 file_accessed(file
);
1604 vma
->vm_ops
= &shmem_vm_ops
;
1605 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1609 static struct inode
*shmem_get_inode(struct super_block
*sb
, const struct inode
*dir
,
1610 int mode
, dev_t dev
, unsigned long flags
)
1612 struct inode
*inode
;
1613 struct shmem_inode_info
*info
;
1614 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1616 if (shmem_reserve_inode(sb
))
1619 inode
= new_inode(sb
);
1621 inode
->i_ino
= get_next_ino();
1622 inode_init_owner(inode
, dir
, mode
);
1623 inode
->i_blocks
= 0;
1624 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1625 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1626 inode
->i_generation
= get_seconds();
1627 info
= SHMEM_I(inode
);
1628 memset(info
, 0, (char *)inode
- (char *)info
);
1629 spin_lock_init(&info
->lock
);
1630 info
->flags
= flags
& VM_NORESERVE
;
1631 INIT_LIST_HEAD(&info
->swaplist
);
1632 INIT_LIST_HEAD(&info
->xattr_list
);
1633 cache_no_acl(inode
);
1635 switch (mode
& S_IFMT
) {
1637 inode
->i_op
= &shmem_special_inode_operations
;
1638 init_special_inode(inode
, mode
, dev
);
1641 inode
->i_mapping
->a_ops
= &shmem_aops
;
1642 inode
->i_op
= &shmem_inode_operations
;
1643 inode
->i_fop
= &shmem_file_operations
;
1644 mpol_shared_policy_init(&info
->policy
,
1645 shmem_get_sbmpol(sbinfo
));
1649 /* Some things misbehave if size == 0 on a directory */
1650 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1651 inode
->i_op
= &shmem_dir_inode_operations
;
1652 inode
->i_fop
= &simple_dir_operations
;
1656 * Must not load anything in the rbtree,
1657 * mpol_free_shared_policy will not be called.
1659 mpol_shared_policy_init(&info
->policy
, NULL
);
1663 shmem_free_inode(sb
);
1668 static const struct inode_operations shmem_symlink_inode_operations
;
1669 static const struct inode_operations shmem_symlink_inline_operations
;
1672 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1673 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1674 * below the loop driver, in the generic fashion that many filesystems support.
1676 static int shmem_readpage(struct file
*file
, struct page
*page
)
1678 struct inode
*inode
= page
->mapping
->host
;
1679 int error
= shmem_getpage(inode
, page
->index
, &page
, SGP_CACHE
, NULL
);
1685 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1686 loff_t pos
, unsigned len
, unsigned flags
,
1687 struct page
**pagep
, void **fsdata
)
1689 struct inode
*inode
= mapping
->host
;
1690 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1692 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1696 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1697 loff_t pos
, unsigned len
, unsigned copied
,
1698 struct page
*page
, void *fsdata
)
1700 struct inode
*inode
= mapping
->host
;
1702 if (pos
+ copied
> inode
->i_size
)
1703 i_size_write(inode
, pos
+ copied
);
1705 set_page_dirty(page
);
1707 page_cache_release(page
);
1712 static void do_shmem_file_read(struct file
*filp
, loff_t
*ppos
, read_descriptor_t
*desc
, read_actor_t actor
)
1714 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
1715 struct address_space
*mapping
= inode
->i_mapping
;
1716 unsigned long index
, offset
;
1717 enum sgp_type sgp
= SGP_READ
;
1720 * Might this read be for a stacking filesystem? Then when reading
1721 * holes of a sparse file, we actually need to allocate those pages,
1722 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1724 if (segment_eq(get_fs(), KERNEL_DS
))
1727 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1728 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1731 struct page
*page
= NULL
;
1732 unsigned long end_index
, nr
, ret
;
1733 loff_t i_size
= i_size_read(inode
);
1735 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1736 if (index
> end_index
)
1738 if (index
== end_index
) {
1739 nr
= i_size
& ~PAGE_CACHE_MASK
;
1744 desc
->error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1746 if (desc
->error
== -EINVAL
)
1754 * We must evaluate after, since reads (unlike writes)
1755 * are called without i_mutex protection against truncate
1757 nr
= PAGE_CACHE_SIZE
;
1758 i_size
= i_size_read(inode
);
1759 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1760 if (index
== end_index
) {
1761 nr
= i_size
& ~PAGE_CACHE_MASK
;
1764 page_cache_release(page
);
1772 * If users can be writing to this page using arbitrary
1773 * virtual addresses, take care about potential aliasing
1774 * before reading the page on the kernel side.
1776 if (mapping_writably_mapped(mapping
))
1777 flush_dcache_page(page
);
1779 * Mark the page accessed if we read the beginning.
1782 mark_page_accessed(page
);
1784 page
= ZERO_PAGE(0);
1785 page_cache_get(page
);
1789 * Ok, we have the page, and it's up-to-date, so
1790 * now we can copy it to user space...
1792 * The actor routine returns how many bytes were actually used..
1793 * NOTE! This may not be the same as how much of a user buffer
1794 * we filled up (we may be padding etc), so we can only update
1795 * "pos" here (the actor routine has to update the user buffer
1796 * pointers and the remaining count).
1798 ret
= actor(desc
, page
, offset
, nr
);
1800 index
+= offset
>> PAGE_CACHE_SHIFT
;
1801 offset
&= ~PAGE_CACHE_MASK
;
1803 page_cache_release(page
);
1804 if (ret
!= nr
|| !desc
->count
)
1810 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1811 file_accessed(filp
);
1814 static ssize_t
shmem_file_aio_read(struct kiocb
*iocb
,
1815 const struct iovec
*iov
, unsigned long nr_segs
, loff_t pos
)
1817 struct file
*filp
= iocb
->ki_filp
;
1821 loff_t
*ppos
= &iocb
->ki_pos
;
1823 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1827 for (seg
= 0; seg
< nr_segs
; seg
++) {
1828 read_descriptor_t desc
;
1831 desc
.arg
.buf
= iov
[seg
].iov_base
;
1832 desc
.count
= iov
[seg
].iov_len
;
1833 if (desc
.count
== 0)
1836 do_shmem_file_read(filp
, ppos
, &desc
, file_read_actor
);
1837 retval
+= desc
.written
;
1839 retval
= retval
?: desc
.error
;
1848 static ssize_t
shmem_file_splice_read(struct file
*in
, loff_t
*ppos
,
1849 struct pipe_inode_info
*pipe
, size_t len
,
1852 struct address_space
*mapping
= in
->f_mapping
;
1853 unsigned int loff
, nr_pages
, req_pages
;
1854 struct page
*pages
[PIPE_DEF_BUFFERS
];
1855 struct partial_page partial
[PIPE_DEF_BUFFERS
];
1857 pgoff_t index
, end_index
;
1860 struct splice_pipe_desc spd
= {
1864 .ops
= &page_cache_pipe_buf_ops
,
1865 .spd_release
= spd_release_page
,
1868 isize
= i_size_read(in
->f_mapping
->host
);
1869 if (unlikely(*ppos
>= isize
))
1872 left
= isize
- *ppos
;
1873 if (unlikely(left
< len
))
1876 if (splice_grow_spd(pipe
, &spd
))
1879 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1880 loff
= *ppos
& ~PAGE_CACHE_MASK
;
1881 req_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1882 nr_pages
= min(req_pages
, pipe
->buffers
);
1885 * Lookup the (hopefully) full range of pages we need.
1887 spd
.nr_pages
= find_get_pages_contig(mapping
, index
,
1888 nr_pages
, spd
.pages
);
1889 index
+= spd
.nr_pages
;
1892 * If find_get_pages_contig() returned fewer pages than we needed,
1893 * readahead/allocate the rest and fill in the holes.
1895 if (spd
.nr_pages
< nr_pages
)
1896 page_cache_sync_readahead(mapping
, &in
->f_ra
, in
,
1897 index
, req_pages
- spd
.nr_pages
);
1900 while (spd
.nr_pages
< nr_pages
) {
1902 * Page could be there, find_get_pages_contig() breaks on
1905 page
= find_get_page(mapping
, index
);
1908 * page didn't exist, allocate one.
1910 page
= page_cache_alloc_cold(mapping
);
1914 error
= add_to_page_cache_lru(page
, mapping
, index
,
1916 if (unlikely(error
)) {
1917 page_cache_release(page
);
1918 if (error
== -EEXIST
)
1923 * add_to_page_cache() locks the page, unlock it
1924 * to avoid convoluting the logic below even more.
1929 spd
.pages
[spd
.nr_pages
++] = page
;
1934 * Now loop over the map and see if we need to start IO on any
1935 * pages, fill in the partial map, etc.
1937 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1938 nr_pages
= spd
.nr_pages
;
1940 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
1941 unsigned int this_len
;
1947 * this_len is the max we'll use from this page
1949 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
1950 page
= spd
.pages
[page_nr
];
1952 if (PageReadahead(page
))
1953 page_cache_async_readahead(mapping
, &in
->f_ra
, in
,
1954 page
, index
, req_pages
- page_nr
);
1957 * If the page isn't uptodate, we may need to start io on it
1959 if (!PageUptodate(page
)) {
1963 * Page was truncated, or invalidated by the
1964 * filesystem. Redo the find/create, but this time the
1965 * page is kept locked, so there's no chance of another
1966 * race with truncate/invalidate.
1968 if (!page
->mapping
) {
1970 page
= find_or_create_page(mapping
, index
,
1971 mapping_gfp_mask(mapping
));
1977 page_cache_release(spd
.pages
[page_nr
]);
1978 spd
.pages
[page_nr
] = page
;
1981 * page was already under io and is now done, great
1983 if (PageUptodate(page
)) {
1989 * need to read in the page
1991 error
= mapping
->a_ops
->readpage(in
, page
);
1992 if (unlikely(error
)) {
1994 * We really should re-lookup the page here,
1995 * but it complicates things a lot. Instead
1996 * lets just do what we already stored, and
1997 * we'll get it the next time we are called.
1999 if (error
== AOP_TRUNCATED_PAGE
)
2007 * i_size must be checked after PageUptodate.
2009 isize
= i_size_read(mapping
->host
);
2010 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
2011 if (unlikely(!isize
|| index
> end_index
))
2015 * if this is the last page, see if we need to shrink
2016 * the length and stop
2018 if (end_index
== index
) {
2022 * max good bytes in this page
2024 plen
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
2029 * force quit after adding this page
2031 this_len
= min(this_len
, plen
- loff
);
2035 spd
.partial
[page_nr
].offset
= loff
;
2036 spd
.partial
[page_nr
].len
= this_len
;
2044 * Release any pages at the end, if we quit early. 'page_nr' is how far
2045 * we got, 'nr_pages' is how many pages are in the map.
2047 while (page_nr
< nr_pages
)
2048 page_cache_release(spd
.pages
[page_nr
++]);
2049 in
->f_ra
.prev_pos
= (loff_t
)index
<< PAGE_CACHE_SHIFT
;
2052 error
= splice_to_pipe(pipe
, &spd
);
2054 splice_shrink_spd(pipe
, &spd
);
2063 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
2065 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
2067 buf
->f_type
= TMPFS_MAGIC
;
2068 buf
->f_bsize
= PAGE_CACHE_SIZE
;
2069 buf
->f_namelen
= NAME_MAX
;
2070 if (sbinfo
->max_blocks
) {
2071 buf
->f_blocks
= sbinfo
->max_blocks
;
2072 buf
->f_bavail
= buf
->f_bfree
=
2073 sbinfo
->max_blocks
- percpu_counter_sum(&sbinfo
->used_blocks
);
2075 if (sbinfo
->max_inodes
) {
2076 buf
->f_files
= sbinfo
->max_inodes
;
2077 buf
->f_ffree
= sbinfo
->free_inodes
;
2079 /* else leave those fields 0 like simple_statfs */
2084 * File creation. Allocate an inode, and we're done..
2087 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
2089 struct inode
*inode
;
2090 int error
= -ENOSPC
;
2092 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, dev
, VM_NORESERVE
);
2094 error
= security_inode_init_security(inode
, dir
,
2095 &dentry
->d_name
, NULL
,
2098 if (error
!= -EOPNOTSUPP
) {
2103 #ifdef CONFIG_TMPFS_POSIX_ACL
2104 error
= generic_acl_init(inode
, dir
);
2112 dir
->i_size
+= BOGO_DIRENT_SIZE
;
2113 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2114 d_instantiate(dentry
, inode
);
2115 dget(dentry
); /* Extra count - pin the dentry in core */
2120 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2124 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
2130 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
2131 struct nameidata
*nd
)
2133 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
2139 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
2141 struct inode
*inode
= old_dentry
->d_inode
;
2145 * No ordinary (disk based) filesystem counts links as inodes;
2146 * but each new link needs a new dentry, pinning lowmem, and
2147 * tmpfs dentries cannot be pruned until they are unlinked.
2149 ret
= shmem_reserve_inode(inode
->i_sb
);
2153 dir
->i_size
+= BOGO_DIRENT_SIZE
;
2154 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2156 ihold(inode
); /* New dentry reference */
2157 dget(dentry
); /* Extra pinning count for the created dentry */
2158 d_instantiate(dentry
, inode
);
2163 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
2165 struct inode
*inode
= dentry
->d_inode
;
2167 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
2168 shmem_free_inode(inode
->i_sb
);
2170 dir
->i_size
-= BOGO_DIRENT_SIZE
;
2171 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2173 dput(dentry
); /* Undo the count from "create" - this does all the work */
2177 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2179 if (!simple_empty(dentry
))
2182 drop_nlink(dentry
->d_inode
);
2184 return shmem_unlink(dir
, dentry
);
2188 * The VFS layer already does all the dentry stuff for rename,
2189 * we just have to decrement the usage count for the target if
2190 * it exists so that the VFS layer correctly free's it when it
2193 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
2195 struct inode
*inode
= old_dentry
->d_inode
;
2196 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
2198 if (!simple_empty(new_dentry
))
2201 if (new_dentry
->d_inode
) {
2202 (void) shmem_unlink(new_dir
, new_dentry
);
2204 drop_nlink(old_dir
);
2205 } else if (they_are_dirs
) {
2206 drop_nlink(old_dir
);
2210 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
2211 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
2212 old_dir
->i_ctime
= old_dir
->i_mtime
=
2213 new_dir
->i_ctime
= new_dir
->i_mtime
=
2214 inode
->i_ctime
= CURRENT_TIME
;
2218 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
2222 struct inode
*inode
;
2223 struct page
*page
= NULL
;
2225 struct shmem_inode_info
*info
;
2227 len
= strlen(symname
) + 1;
2228 if (len
> PAGE_CACHE_SIZE
)
2229 return -ENAMETOOLONG
;
2231 inode
= shmem_get_inode(dir
->i_sb
, dir
, S_IFLNK
|S_IRWXUGO
, 0, VM_NORESERVE
);
2235 error
= security_inode_init_security(inode
, dir
, &dentry
->d_name
, NULL
,
2238 if (error
!= -EOPNOTSUPP
) {
2245 info
= SHMEM_I(inode
);
2246 inode
->i_size
= len
-1;
2247 if (len
<= SHMEM_SYMLINK_INLINE_LEN
) {
2249 memcpy(info
->inline_symlink
, symname
, len
);
2250 inode
->i_op
= &shmem_symlink_inline_operations
;
2252 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
2257 inode
->i_mapping
->a_ops
= &shmem_aops
;
2258 inode
->i_op
= &shmem_symlink_inode_operations
;
2259 kaddr
= kmap_atomic(page
, KM_USER0
);
2260 memcpy(kaddr
, symname
, len
);
2261 kunmap_atomic(kaddr
, KM_USER0
);
2262 set_page_dirty(page
);
2264 page_cache_release(page
);
2266 dir
->i_size
+= BOGO_DIRENT_SIZE
;
2267 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2268 d_instantiate(dentry
, inode
);
2273 static void *shmem_follow_link_inline(struct dentry
*dentry
, struct nameidata
*nd
)
2275 nd_set_link(nd
, SHMEM_I(dentry
->d_inode
)->inline_symlink
);
2279 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
2281 struct page
*page
= NULL
;
2282 int res
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
2283 nd_set_link(nd
, res
? ERR_PTR(res
) : kmap(page
));
2289 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2291 if (!IS_ERR(nd_get_link(nd
))) {
2292 struct page
*page
= cookie
;
2294 mark_page_accessed(page
);
2295 page_cache_release(page
);
2299 #ifdef CONFIG_TMPFS_XATTR
2301 * Superblocks without xattr inode operations may get some security.* xattr
2302 * support from the LSM "for free". As soon as we have any other xattrs
2303 * like ACLs, we also need to implement the security.* handlers at
2304 * filesystem level, though.
2307 static int shmem_xattr_get(struct dentry
*dentry
, const char *name
,
2308 void *buffer
, size_t size
)
2310 struct shmem_inode_info
*info
;
2311 struct shmem_xattr
*xattr
;
2314 info
= SHMEM_I(dentry
->d_inode
);
2316 spin_lock(&info
->lock
);
2317 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
2318 if (strcmp(name
, xattr
->name
))
2323 if (size
< xattr
->size
)
2326 memcpy(buffer
, xattr
->value
, xattr
->size
);
2330 spin_unlock(&info
->lock
);
2334 static int shmem_xattr_set(struct dentry
*dentry
, const char *name
,
2335 const void *value
, size_t size
, int flags
)
2337 struct inode
*inode
= dentry
->d_inode
;
2338 struct shmem_inode_info
*info
= SHMEM_I(inode
);
2339 struct shmem_xattr
*xattr
;
2340 struct shmem_xattr
*new_xattr
= NULL
;
2344 /* value == NULL means remove */
2347 len
= sizeof(*new_xattr
) + size
;
2348 if (len
<= sizeof(*new_xattr
))
2351 new_xattr
= kmalloc(len
, GFP_KERNEL
);
2355 new_xattr
->name
= kstrdup(name
, GFP_KERNEL
);
2356 if (!new_xattr
->name
) {
2361 new_xattr
->size
= size
;
2362 memcpy(new_xattr
->value
, value
, size
);
2365 spin_lock(&info
->lock
);
2366 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
2367 if (!strcmp(name
, xattr
->name
)) {
2368 if (flags
& XATTR_CREATE
) {
2371 } else if (new_xattr
) {
2372 list_replace(&xattr
->list
, &new_xattr
->list
);
2374 list_del(&xattr
->list
);
2379 if (flags
& XATTR_REPLACE
) {
2383 list_add(&new_xattr
->list
, &info
->xattr_list
);
2387 spin_unlock(&info
->lock
);
2395 static const struct xattr_handler
*shmem_xattr_handlers
[] = {
2396 #ifdef CONFIG_TMPFS_POSIX_ACL
2397 &generic_acl_access_handler
,
2398 &generic_acl_default_handler
,
2403 static int shmem_xattr_validate(const char *name
)
2405 struct { const char *prefix
; size_t len
; } arr
[] = {
2406 { XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
},
2407 { XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
}
2411 for (i
= 0; i
< ARRAY_SIZE(arr
); i
++) {
2412 size_t preflen
= arr
[i
].len
;
2413 if (strncmp(name
, arr
[i
].prefix
, preflen
) == 0) {
2422 static ssize_t
shmem_getxattr(struct dentry
*dentry
, const char *name
,
2423 void *buffer
, size_t size
)
2428 * If this is a request for a synthetic attribute in the system.*
2429 * namespace use the generic infrastructure to resolve a handler
2430 * for it via sb->s_xattr.
2432 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2433 return generic_getxattr(dentry
, name
, buffer
, size
);
2435 err
= shmem_xattr_validate(name
);
2439 return shmem_xattr_get(dentry
, name
, buffer
, size
);
2442 static int shmem_setxattr(struct dentry
*dentry
, const char *name
,
2443 const void *value
, size_t size
, int flags
)
2448 * If this is a request for a synthetic attribute in the system.*
2449 * namespace use the generic infrastructure to resolve a handler
2450 * for it via sb->s_xattr.
2452 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2453 return generic_setxattr(dentry
, name
, value
, size
, flags
);
2455 err
= shmem_xattr_validate(name
);
2460 value
= ""; /* empty EA, do not remove */
2462 return shmem_xattr_set(dentry
, name
, value
, size
, flags
);
2466 static int shmem_removexattr(struct dentry
*dentry
, const char *name
)
2471 * If this is a request for a synthetic attribute in the system.*
2472 * namespace use the generic infrastructure to resolve a handler
2473 * for it via sb->s_xattr.
2475 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2476 return generic_removexattr(dentry
, name
);
2478 err
= shmem_xattr_validate(name
);
2482 return shmem_xattr_set(dentry
, name
, NULL
, 0, XATTR_REPLACE
);
2485 static bool xattr_is_trusted(const char *name
)
2487 return !strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
);
2490 static ssize_t
shmem_listxattr(struct dentry
*dentry
, char *buffer
, size_t size
)
2492 bool trusted
= capable(CAP_SYS_ADMIN
);
2493 struct shmem_xattr
*xattr
;
2494 struct shmem_inode_info
*info
;
2497 info
= SHMEM_I(dentry
->d_inode
);
2499 spin_lock(&info
->lock
);
2500 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
2503 /* skip "trusted." attributes for unprivileged callers */
2504 if (!trusted
&& xattr_is_trusted(xattr
->name
))
2507 len
= strlen(xattr
->name
) + 1;
2514 memcpy(buffer
, xattr
->name
, len
);
2518 spin_unlock(&info
->lock
);
2522 #endif /* CONFIG_TMPFS_XATTR */
2524 static const struct inode_operations shmem_symlink_inline_operations
= {
2525 .readlink
= generic_readlink
,
2526 .follow_link
= shmem_follow_link_inline
,
2527 #ifdef CONFIG_TMPFS_XATTR
2528 .setxattr
= shmem_setxattr
,
2529 .getxattr
= shmem_getxattr
,
2530 .listxattr
= shmem_listxattr
,
2531 .removexattr
= shmem_removexattr
,
2535 static const struct inode_operations shmem_symlink_inode_operations
= {
2536 .readlink
= generic_readlink
,
2537 .follow_link
= shmem_follow_link
,
2538 .put_link
= shmem_put_link
,
2539 #ifdef CONFIG_TMPFS_XATTR
2540 .setxattr
= shmem_setxattr
,
2541 .getxattr
= shmem_getxattr
,
2542 .listxattr
= shmem_listxattr
,
2543 .removexattr
= shmem_removexattr
,
2547 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2549 return ERR_PTR(-ESTALE
);
2552 static int shmem_match(struct inode
*ino
, void *vfh
)
2556 inum
= (inum
<< 32) | fh
[1];
2557 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2560 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
2561 struct fid
*fid
, int fh_len
, int fh_type
)
2563 struct inode
*inode
;
2564 struct dentry
*dentry
= NULL
;
2565 u64 inum
= fid
->raw
[2];
2566 inum
= (inum
<< 32) | fid
->raw
[1];
2571 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
2572 shmem_match
, fid
->raw
);
2574 dentry
= d_find_alias(inode
);
2581 static int shmem_encode_fh(struct dentry
*dentry
, __u32
*fh
, int *len
,
2584 struct inode
*inode
= dentry
->d_inode
;
2591 if (inode_unhashed(inode
)) {
2592 /* Unfortunately insert_inode_hash is not idempotent,
2593 * so as we hash inodes here rather than at creation
2594 * time, we need a lock to ensure we only try
2597 static DEFINE_SPINLOCK(lock
);
2599 if (inode_unhashed(inode
))
2600 __insert_inode_hash(inode
,
2601 inode
->i_ino
+ inode
->i_generation
);
2605 fh
[0] = inode
->i_generation
;
2606 fh
[1] = inode
->i_ino
;
2607 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2613 static const struct export_operations shmem_export_ops
= {
2614 .get_parent
= shmem_get_parent
,
2615 .encode_fh
= shmem_encode_fh
,
2616 .fh_to_dentry
= shmem_fh_to_dentry
,
2619 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2622 char *this_char
, *value
, *rest
;
2624 while (options
!= NULL
) {
2625 this_char
= options
;
2628 * NUL-terminate this option: unfortunately,
2629 * mount options form a comma-separated list,
2630 * but mpol's nodelist may also contain commas.
2632 options
= strchr(options
, ',');
2633 if (options
== NULL
)
2636 if (!isdigit(*options
)) {
2643 if ((value
= strchr(this_char
,'=')) != NULL
) {
2647 "tmpfs: No value for mount option '%s'\n",
2652 if (!strcmp(this_char
,"size")) {
2653 unsigned long long size
;
2654 size
= memparse(value
,&rest
);
2656 size
<<= PAGE_SHIFT
;
2657 size
*= totalram_pages
;
2663 sbinfo
->max_blocks
=
2664 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2665 } else if (!strcmp(this_char
,"nr_blocks")) {
2666 sbinfo
->max_blocks
= memparse(value
, &rest
);
2669 } else if (!strcmp(this_char
,"nr_inodes")) {
2670 sbinfo
->max_inodes
= memparse(value
, &rest
);
2673 } else if (!strcmp(this_char
,"mode")) {
2676 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2679 } else if (!strcmp(this_char
,"uid")) {
2682 sbinfo
->uid
= simple_strtoul(value
, &rest
, 0);
2685 } else if (!strcmp(this_char
,"gid")) {
2688 sbinfo
->gid
= simple_strtoul(value
, &rest
, 0);
2691 } else if (!strcmp(this_char
,"mpol")) {
2692 if (mpol_parse_str(value
, &sbinfo
->mpol
, 1))
2695 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2703 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2709 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2711 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2712 struct shmem_sb_info config
= *sbinfo
;
2713 unsigned long inodes
;
2714 int error
= -EINVAL
;
2716 if (shmem_parse_options(data
, &config
, true))
2719 spin_lock(&sbinfo
->stat_lock
);
2720 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2721 if (percpu_counter_compare(&sbinfo
->used_blocks
, config
.max_blocks
) > 0)
2723 if (config
.max_inodes
< inodes
)
2726 * Those tests also disallow limited->unlimited while any are in
2727 * use, so i_blocks will always be zero when max_blocks is zero;
2728 * but we must separately disallow unlimited->limited, because
2729 * in that case we have no record of how much is already in use.
2731 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2733 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2737 sbinfo
->max_blocks
= config
.max_blocks
;
2738 sbinfo
->max_inodes
= config
.max_inodes
;
2739 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2741 mpol_put(sbinfo
->mpol
);
2742 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2744 spin_unlock(&sbinfo
->stat_lock
);
2748 static int shmem_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
2750 struct shmem_sb_info
*sbinfo
= SHMEM_SB(vfs
->mnt_sb
);
2752 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2753 seq_printf(seq
, ",size=%luk",
2754 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2755 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2756 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2757 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2758 seq_printf(seq
, ",mode=%03o", sbinfo
->mode
);
2759 if (sbinfo
->uid
!= 0)
2760 seq_printf(seq
, ",uid=%u", sbinfo
->uid
);
2761 if (sbinfo
->gid
!= 0)
2762 seq_printf(seq
, ",gid=%u", sbinfo
->gid
);
2763 shmem_show_mpol(seq
, sbinfo
->mpol
);
2766 #endif /* CONFIG_TMPFS */
2768 static void shmem_put_super(struct super_block
*sb
)
2770 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2772 percpu_counter_destroy(&sbinfo
->used_blocks
);
2774 sb
->s_fs_info
= NULL
;
2777 int shmem_fill_super(struct super_block
*sb
, void *data
, int silent
)
2779 struct inode
*inode
;
2780 struct dentry
*root
;
2781 struct shmem_sb_info
*sbinfo
;
2784 /* Round up to L1_CACHE_BYTES to resist false sharing */
2785 sbinfo
= kzalloc(max((int)sizeof(struct shmem_sb_info
),
2786 L1_CACHE_BYTES
), GFP_KERNEL
);
2790 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2791 sbinfo
->uid
= current_fsuid();
2792 sbinfo
->gid
= current_fsgid();
2793 sb
->s_fs_info
= sbinfo
;
2797 * Per default we only allow half of the physical ram per
2798 * tmpfs instance, limiting inodes to one per page of lowmem;
2799 * but the internal instance is left unlimited.
2801 if (!(sb
->s_flags
& MS_NOUSER
)) {
2802 sbinfo
->max_blocks
= shmem_default_max_blocks();
2803 sbinfo
->max_inodes
= shmem_default_max_inodes();
2804 if (shmem_parse_options(data
, sbinfo
, false)) {
2809 sb
->s_export_op
= &shmem_export_ops
;
2811 sb
->s_flags
|= MS_NOUSER
;
2814 spin_lock_init(&sbinfo
->stat_lock
);
2815 if (percpu_counter_init(&sbinfo
->used_blocks
, 0))
2817 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2819 sb
->s_maxbytes
= SHMEM_MAX_BYTES
;
2820 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2821 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2822 sb
->s_magic
= TMPFS_MAGIC
;
2823 sb
->s_op
= &shmem_ops
;
2824 sb
->s_time_gran
= 1;
2825 #ifdef CONFIG_TMPFS_XATTR
2826 sb
->s_xattr
= shmem_xattr_handlers
;
2828 #ifdef CONFIG_TMPFS_POSIX_ACL
2829 sb
->s_flags
|= MS_POSIXACL
;
2832 inode
= shmem_get_inode(sb
, NULL
, S_IFDIR
| sbinfo
->mode
, 0, VM_NORESERVE
);
2835 inode
->i_uid
= sbinfo
->uid
;
2836 inode
->i_gid
= sbinfo
->gid
;
2837 root
= d_alloc_root(inode
);
2846 shmem_put_super(sb
);
2850 static struct kmem_cache
*shmem_inode_cachep
;
2852 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2854 struct shmem_inode_info
*p
;
2855 p
= (struct shmem_inode_info
*)kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2858 return &p
->vfs_inode
;
2861 static void shmem_i_callback(struct rcu_head
*head
)
2863 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
2864 INIT_LIST_HEAD(&inode
->i_dentry
);
2865 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2868 static void shmem_destroy_inode(struct inode
*inode
)
2870 if ((inode
->i_mode
& S_IFMT
) == S_IFREG
) {
2871 /* only struct inode is valid if it's an inline symlink */
2872 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2874 call_rcu(&inode
->i_rcu
, shmem_i_callback
);
2877 static void init_once(void *foo
)
2879 struct shmem_inode_info
*p
= (struct shmem_inode_info
*) foo
;
2881 inode_init_once(&p
->vfs_inode
);
2884 static int init_inodecache(void)
2886 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2887 sizeof(struct shmem_inode_info
),
2888 0, SLAB_PANIC
, init_once
);
2892 static void destroy_inodecache(void)
2894 kmem_cache_destroy(shmem_inode_cachep
);
2897 static const struct address_space_operations shmem_aops
= {
2898 .writepage
= shmem_writepage
,
2899 .set_page_dirty
= __set_page_dirty_no_writeback
,
2901 .readpage
= shmem_readpage
,
2902 .write_begin
= shmem_write_begin
,
2903 .write_end
= shmem_write_end
,
2905 .migratepage
= migrate_page
,
2906 .error_remove_page
= generic_error_remove_page
,
2909 static const struct file_operations shmem_file_operations
= {
2912 .llseek
= generic_file_llseek
,
2913 .read
= do_sync_read
,
2914 .write
= do_sync_write
,
2915 .aio_read
= shmem_file_aio_read
,
2916 .aio_write
= generic_file_aio_write
,
2917 .fsync
= noop_fsync
,
2918 .splice_read
= shmem_file_splice_read
,
2919 .splice_write
= generic_file_splice_write
,
2923 static const struct inode_operations shmem_inode_operations
= {
2924 .setattr
= shmem_setattr
,
2925 .truncate_range
= shmem_truncate_range
,
2926 #ifdef CONFIG_TMPFS_XATTR
2927 .setxattr
= shmem_setxattr
,
2928 .getxattr
= shmem_getxattr
,
2929 .listxattr
= shmem_listxattr
,
2930 .removexattr
= shmem_removexattr
,
2932 #ifdef CONFIG_TMPFS_POSIX_ACL
2933 .check_acl
= generic_check_acl
,
2938 static const struct inode_operations shmem_dir_inode_operations
= {
2940 .create
= shmem_create
,
2941 .lookup
= simple_lookup
,
2943 .unlink
= shmem_unlink
,
2944 .symlink
= shmem_symlink
,
2945 .mkdir
= shmem_mkdir
,
2946 .rmdir
= shmem_rmdir
,
2947 .mknod
= shmem_mknod
,
2948 .rename
= shmem_rename
,
2950 #ifdef CONFIG_TMPFS_XATTR
2951 .setxattr
= shmem_setxattr
,
2952 .getxattr
= shmem_getxattr
,
2953 .listxattr
= shmem_listxattr
,
2954 .removexattr
= shmem_removexattr
,
2956 #ifdef CONFIG_TMPFS_POSIX_ACL
2957 .setattr
= shmem_setattr
,
2958 .check_acl
= generic_check_acl
,
2962 static const struct inode_operations shmem_special_inode_operations
= {
2963 #ifdef CONFIG_TMPFS_XATTR
2964 .setxattr
= shmem_setxattr
,
2965 .getxattr
= shmem_getxattr
,
2966 .listxattr
= shmem_listxattr
,
2967 .removexattr
= shmem_removexattr
,
2969 #ifdef CONFIG_TMPFS_POSIX_ACL
2970 .setattr
= shmem_setattr
,
2971 .check_acl
= generic_check_acl
,
2975 static const struct super_operations shmem_ops
= {
2976 .alloc_inode
= shmem_alloc_inode
,
2977 .destroy_inode
= shmem_destroy_inode
,
2979 .statfs
= shmem_statfs
,
2980 .remount_fs
= shmem_remount_fs
,
2981 .show_options
= shmem_show_options
,
2983 .evict_inode
= shmem_evict_inode
,
2984 .drop_inode
= generic_delete_inode
,
2985 .put_super
= shmem_put_super
,
2988 static const struct vm_operations_struct shmem_vm_ops
= {
2989 .fault
= shmem_fault
,
2991 .set_policy
= shmem_set_policy
,
2992 .get_policy
= shmem_get_policy
,
2997 static struct dentry
*shmem_mount(struct file_system_type
*fs_type
,
2998 int flags
, const char *dev_name
, void *data
)
3000 return mount_nodev(fs_type
, flags
, data
, shmem_fill_super
);
3003 static struct file_system_type tmpfs_fs_type
= {
3004 .owner
= THIS_MODULE
,
3006 .mount
= shmem_mount
,
3007 .kill_sb
= kill_litter_super
,
3010 int __init
init_tmpfs(void)
3014 error
= bdi_init(&shmem_backing_dev_info
);
3018 error
= init_inodecache();
3022 error
= register_filesystem(&tmpfs_fs_type
);
3024 printk(KERN_ERR
"Could not register tmpfs\n");
3028 shm_mnt
= vfs_kern_mount(&tmpfs_fs_type
, MS_NOUSER
,
3029 tmpfs_fs_type
.name
, NULL
);
3030 if (IS_ERR(shm_mnt
)) {
3031 error
= PTR_ERR(shm_mnt
);
3032 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
3038 unregister_filesystem(&tmpfs_fs_type
);
3040 destroy_inodecache();
3042 bdi_destroy(&shmem_backing_dev_info
);
3044 shm_mnt
= ERR_PTR(error
);
3048 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
3050 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
3051 * @inode: the inode to be searched
3052 * @pgoff: the offset to be searched
3053 * @pagep: the pointer for the found page to be stored
3054 * @ent: the pointer for the found swap entry to be stored
3056 * If a page is found, refcount of it is incremented. Callers should handle
3059 void mem_cgroup_get_shmem_target(struct inode
*inode
, pgoff_t pgoff
,
3060 struct page
**pagep
, swp_entry_t
*ent
)
3062 swp_entry_t entry
= { .val
= 0 }, *ptr
;
3063 struct page
*page
= NULL
;
3064 struct shmem_inode_info
*info
= SHMEM_I(inode
);
3066 if ((pgoff
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
3069 spin_lock(&info
->lock
);
3070 ptr
= shmem_swp_entry(info
, pgoff
, NULL
);
3072 if (ptr
&& ptr
->val
) {
3073 entry
.val
= ptr
->val
;
3074 page
= find_get_page(&swapper_space
, entry
.val
);
3077 page
= find_get_page(inode
->i_mapping
, pgoff
);
3079 shmem_swp_unmap(ptr
);
3080 spin_unlock(&info
->lock
);
3087 #else /* !CONFIG_SHMEM */
3090 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
3092 * This is intended for small system where the benefits of the full
3093 * shmem code (swap-backed and resource-limited) are outweighed by
3094 * their complexity. On systems without swap this code should be
3095 * effectively equivalent, but much lighter weight.
3098 #include <linux/ramfs.h>
3100 static struct file_system_type tmpfs_fs_type
= {
3102 .mount
= ramfs_mount
,
3103 .kill_sb
= kill_litter_super
,
3106 int __init
init_tmpfs(void)
3108 BUG_ON(register_filesystem(&tmpfs_fs_type
) != 0);
3110 shm_mnt
= kern_mount(&tmpfs_fs_type
);
3111 BUG_ON(IS_ERR(shm_mnt
));
3116 int shmem_unuse(swp_entry_t entry
, struct page
*page
)
3121 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
3126 void shmem_truncate_range(struct inode
*inode
, loff_t start
, loff_t end
)
3128 truncate_inode_pages_range(inode
->i_mapping
, start
, end
);
3130 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
3132 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
3134 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
3135 * @inode: the inode to be searched
3136 * @pgoff: the offset to be searched
3137 * @pagep: the pointer for the found page to be stored
3138 * @ent: the pointer for the found swap entry to be stored
3140 * If a page is found, refcount of it is incremented. Callers should handle
3143 void mem_cgroup_get_shmem_target(struct inode
*inode
, pgoff_t pgoff
,
3144 struct page
**pagep
, swp_entry_t
*ent
)
3146 struct page
*page
= NULL
;
3148 if ((pgoff
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
3150 page
= find_get_page(inode
->i_mapping
, pgoff
);
3153 *ent
= (swp_entry_t
){ .val
= 0 };
3157 #define shmem_vm_ops generic_file_vm_ops
3158 #define shmem_file_operations ramfs_file_operations
3159 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
3160 #define shmem_acct_size(flags, size) 0
3161 #define shmem_unacct_size(flags, size) do {} while (0)
3162 #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
3164 #endif /* CONFIG_SHMEM */
3169 * shmem_file_setup - get an unlinked file living in tmpfs
3170 * @name: name for dentry (to be seen in /proc/<pid>/maps
3171 * @size: size to be set for the file
3172 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
3174 struct file
*shmem_file_setup(const char *name
, loff_t size
, unsigned long flags
)
3178 struct inode
*inode
;
3180 struct dentry
*root
;
3183 if (IS_ERR(shm_mnt
))
3184 return (void *)shm_mnt
;
3186 if (size
< 0 || size
> SHMEM_MAX_BYTES
)
3187 return ERR_PTR(-EINVAL
);
3189 if (shmem_acct_size(flags
, size
))
3190 return ERR_PTR(-ENOMEM
);
3194 this.len
= strlen(name
);
3195 this.hash
= 0; /* will go */
3196 root
= shm_mnt
->mnt_root
;
3197 path
.dentry
= d_alloc(root
, &this);
3200 path
.mnt
= mntget(shm_mnt
);
3203 inode
= shmem_get_inode(root
->d_sb
, NULL
, S_IFREG
| S_IRWXUGO
, 0, flags
);
3207 d_instantiate(path
.dentry
, inode
);
3208 inode
->i_size
= size
;
3209 inode
->i_nlink
= 0; /* It is unlinked */
3211 error
= ramfs_nommu_expand_for_mapping(inode
, size
);
3217 file
= alloc_file(&path
, FMODE_WRITE
| FMODE_READ
,
3218 &shmem_file_operations
);
3227 shmem_unacct_size(flags
, size
);
3228 return ERR_PTR(error
);
3230 EXPORT_SYMBOL_GPL(shmem_file_setup
);
3233 * shmem_zero_setup - setup a shared anonymous mapping
3234 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
3236 int shmem_zero_setup(struct vm_area_struct
*vma
)
3239 loff_t size
= vma
->vm_end
- vma
->vm_start
;
3241 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
3243 return PTR_ERR(file
);
3247 vma
->vm_file
= file
;
3248 vma
->vm_ops
= &shmem_vm_ops
;
3249 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
3254 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
3255 * @mapping: the page's address_space
3256 * @index: the page index
3257 * @gfp: the page allocator flags to use if allocating
3259 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
3260 * with any new page allocations done using the specified allocation flags.
3261 * But read_cache_page_gfp() uses the ->readpage() method: which does not
3262 * suit tmpfs, since it may have pages in swapcache, and needs to find those
3263 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
3265 * Provide a stub for those callers to start using now, then later
3266 * flesh it out to call shmem_getpage() with additional gfp mask, when
3267 * shmem_file_splice_read() is added and shmem_readpage() is removed.
3269 struct page
*shmem_read_mapping_page_gfp(struct address_space
*mapping
,
3270 pgoff_t index
, gfp_t gfp
)
3272 return read_cache_page_gfp(mapping
, index
, gfp
);
3274 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp
);