2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 * This file is released under the GPL.
24 #include <linux/init.h>
25 #include <linux/vfs.h>
26 #include <linux/mount.h>
27 #include <linux/pagemap.h>
28 #include <linux/file.h>
30 #include <linux/module.h>
31 #include <linux/swap.h>
33 static struct vfsmount
*shm_mnt
;
37 * This virtual memory filesystem is heavily based on the ramfs. It
38 * extends ramfs by the ability to use swap and honor resource limits
39 * which makes it a completely usable filesystem.
42 #include <linux/xattr.h>
43 #include <linux/exportfs.h>
44 #include <linux/posix_acl.h>
45 #include <linux/generic_acl.h>
46 #include <linux/mman.h>
47 #include <linux/string.h>
48 #include <linux/slab.h>
49 #include <linux/backing-dev.h>
50 #include <linux/shmem_fs.h>
51 #include <linux/writeback.h>
52 #include <linux/blkdev.h>
53 #include <linux/pagevec.h>
54 #include <linux/percpu_counter.h>
55 #include <linux/splice.h>
56 #include <linux/security.h>
57 #include <linux/swapops.h>
58 #include <linux/mempolicy.h>
59 #include <linux/namei.h>
60 #include <linux/ctype.h>
61 #include <linux/migrate.h>
62 #include <linux/highmem.h>
63 #include <linux/seq_file.h>
64 #include <linux/magic.h>
66 #include <asm/uaccess.h>
67 #include <asm/pgtable.h>
69 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
70 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
72 /* Pretend that each entry is of this size in directory's i_size */
73 #define BOGO_DIRENT_SIZE 20
76 struct list_head list
; /* anchored by shmem_inode_info->xattr_list */
77 char *name
; /* xattr name */
82 /* Flag allocation requirements to shmem_getpage */
84 SGP_READ
, /* don't exceed i_size, don't allocate page */
85 SGP_CACHE
, /* don't exceed i_size, may allocate page */
86 SGP_DIRTY
, /* like SGP_CACHE, but set new page dirty */
87 SGP_WRITE
, /* may exceed i_size, may allocate page */
91 static unsigned long shmem_default_max_blocks(void)
93 return totalram_pages
/ 2;
96 static unsigned long shmem_default_max_inodes(void)
98 return min(totalram_pages
- totalhigh_pages
, totalram_pages
/ 2);
102 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
103 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
);
105 static inline int shmem_getpage(struct inode
*inode
, pgoff_t index
,
106 struct page
**pagep
, enum sgp_type sgp
, int *fault_type
)
108 return shmem_getpage_gfp(inode
, index
, pagep
, sgp
,
109 mapping_gfp_mask(inode
->i_mapping
), fault_type
);
112 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
114 return sb
->s_fs_info
;
118 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
119 * for shared memory and for shared anonymous (/dev/zero) mappings
120 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
121 * consistent with the pre-accounting of private mappings ...
123 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
125 return (flags
& VM_NORESERVE
) ?
126 0 : security_vm_enough_memory_kern(VM_ACCT(size
));
129 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
131 if (!(flags
& VM_NORESERVE
))
132 vm_unacct_memory(VM_ACCT(size
));
136 * ... whereas tmpfs objects are accounted incrementally as
137 * pages are allocated, in order to allow huge sparse files.
138 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
139 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
141 static inline int shmem_acct_block(unsigned long flags
)
143 return (flags
& VM_NORESERVE
) ?
144 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE
)) : 0;
147 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
149 if (flags
& VM_NORESERVE
)
150 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
153 static const struct super_operations shmem_ops
;
154 static const struct address_space_operations shmem_aops
;
155 static const struct file_operations shmem_file_operations
;
156 static const struct inode_operations shmem_inode_operations
;
157 static const struct inode_operations shmem_dir_inode_operations
;
158 static const struct inode_operations shmem_special_inode_operations
;
159 static const struct vm_operations_struct shmem_vm_ops
;
161 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
162 .ra_pages
= 0, /* No readahead */
163 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
| BDI_CAP_SWAP_BACKED
,
166 static LIST_HEAD(shmem_swaplist
);
167 static DEFINE_MUTEX(shmem_swaplist_mutex
);
169 static int shmem_reserve_inode(struct super_block
*sb
)
171 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
172 if (sbinfo
->max_inodes
) {
173 spin_lock(&sbinfo
->stat_lock
);
174 if (!sbinfo
->free_inodes
) {
175 spin_unlock(&sbinfo
->stat_lock
);
178 sbinfo
->free_inodes
--;
179 spin_unlock(&sbinfo
->stat_lock
);
184 static void shmem_free_inode(struct super_block
*sb
)
186 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
187 if (sbinfo
->max_inodes
) {
188 spin_lock(&sbinfo
->stat_lock
);
189 sbinfo
->free_inodes
++;
190 spin_unlock(&sbinfo
->stat_lock
);
195 * shmem_recalc_inode - recalculate the block usage of an inode
196 * @inode: inode to recalc
198 * We have to calculate the free blocks since the mm can drop
199 * undirtied hole pages behind our back.
201 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
202 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
204 * It has to be called with the spinlock held.
206 static void shmem_recalc_inode(struct inode
*inode
)
208 struct shmem_inode_info
*info
= SHMEM_I(inode
);
211 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
213 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
214 if (sbinfo
->max_blocks
)
215 percpu_counter_add(&sbinfo
->used_blocks
, -freed
);
216 info
->alloced
-= freed
;
217 inode
->i_blocks
-= freed
* BLOCKS_PER_PAGE
;
218 shmem_unacct_blocks(info
->flags
, freed
);
222 static void shmem_put_swap(struct shmem_inode_info
*info
, pgoff_t index
,
225 if (index
< SHMEM_NR_DIRECT
)
226 info
->i_direct
[index
] = swap
;
229 static swp_entry_t
shmem_get_swap(struct shmem_inode_info
*info
, pgoff_t index
)
231 return (index
< SHMEM_NR_DIRECT
) ?
232 info
->i_direct
[index
] : (swp_entry_t
){0};
236 * Replace item expected in radix tree by a new item, while holding tree lock.
238 static int shmem_radix_tree_replace(struct address_space
*mapping
,
239 pgoff_t index
, void *expected
, void *replacement
)
244 VM_BUG_ON(!expected
);
245 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
, index
);
247 item
= radix_tree_deref_slot_protected(pslot
,
248 &mapping
->tree_lock
);
249 if (item
!= expected
)
252 radix_tree_replace_slot(pslot
, replacement
);
254 radix_tree_delete(&mapping
->page_tree
, index
);
259 * Like add_to_page_cache_locked, but error if expected item has gone.
261 static int shmem_add_to_page_cache(struct page
*page
,
262 struct address_space
*mapping
,
263 pgoff_t index
, gfp_t gfp
, void *expected
)
267 VM_BUG_ON(!PageLocked(page
));
268 VM_BUG_ON(!PageSwapBacked(page
));
270 error
= mem_cgroup_cache_charge(page
, current
->mm
,
271 gfp
& GFP_RECLAIM_MASK
);
275 error
= radix_tree_preload(gfp
& GFP_RECLAIM_MASK
);
277 page_cache_get(page
);
278 page
->mapping
= mapping
;
281 spin_lock_irq(&mapping
->tree_lock
);
283 error
= radix_tree_insert(&mapping
->page_tree
,
286 error
= shmem_radix_tree_replace(mapping
, index
,
290 __inc_zone_page_state(page
, NR_FILE_PAGES
);
291 __inc_zone_page_state(page
, NR_SHMEM
);
292 spin_unlock_irq(&mapping
->tree_lock
);
294 page
->mapping
= NULL
;
295 spin_unlock_irq(&mapping
->tree_lock
);
296 page_cache_release(page
);
299 radix_tree_preload_end();
302 mem_cgroup_uncharge_cache_page(page
);
308 * Like find_get_pages, but collecting swap entries as well as pages.
310 static unsigned shmem_find_get_pages_and_swap(struct address_space
*mapping
,
311 pgoff_t start
, unsigned int nr_pages
,
312 struct page
**pages
, pgoff_t
*indices
)
316 unsigned int nr_found
;
320 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
321 (void ***)pages
, indices
, start
, nr_pages
);
323 for (i
= 0; i
< nr_found
; i
++) {
326 page
= radix_tree_deref_slot((void **)pages
[i
]);
329 if (radix_tree_exception(page
)) {
330 if (radix_tree_exceptional_entry(page
))
332 /* radix_tree_deref_retry(page) */
335 if (!page_cache_get_speculative(page
))
338 /* Has the page moved? */
339 if (unlikely(page
!= *((void **)pages
[i
]))) {
340 page_cache_release(page
);
344 indices
[ret
] = indices
[i
];
348 if (unlikely(!ret
&& nr_found
))
355 * Lockless lookup of swap entry in radix tree, avoiding refcount on pages.
357 static pgoff_t
shmem_find_swap(struct address_space
*mapping
, void *radswap
)
359 void **slots
[PAGEVEC_SIZE
];
360 pgoff_t indices
[PAGEVEC_SIZE
];
361 unsigned int nr_found
;
367 pgoff_t index
= indices
[nr_found
- 1] + 1;
371 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
372 slots
, indices
, index
, PAGEVEC_SIZE
);
373 for (i
= 0; i
< nr_found
; i
++) {
374 void *item
= radix_tree_deref_slot(slots
[i
]);
375 if (radix_tree_deref_retry(item
)) {
379 if (item
== radswap
) {
391 * Remove swap entry from radix tree, free the swap and its page cache.
393 static int shmem_free_swap(struct address_space
*mapping
,
394 pgoff_t index
, void *radswap
)
398 spin_lock_irq(&mapping
->tree_lock
);
399 error
= shmem_radix_tree_replace(mapping
, index
, radswap
, NULL
);
400 spin_unlock_irq(&mapping
->tree_lock
);
402 free_swap_and_cache(radix_to_swp_entry(radswap
));
407 * Pagevec may contain swap entries, so shuffle up pages before releasing.
409 static void shmem_pagevec_release(struct pagevec
*pvec
)
413 for (i
= 0, j
= 0; i
< pagevec_count(pvec
); i
++) {
414 struct page
*page
= pvec
->pages
[i
];
415 if (!radix_tree_exceptional_entry(page
))
416 pvec
->pages
[j
++] = page
;
419 pagevec_release(pvec
);
423 * Remove range of pages and swap entries from radix tree, and free them.
425 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
427 struct address_space
*mapping
= inode
->i_mapping
;
428 struct shmem_inode_info
*info
= SHMEM_I(inode
);
429 pgoff_t start
= (lstart
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
430 unsigned partial
= lstart
& (PAGE_CACHE_SIZE
- 1);
431 pgoff_t end
= (lend
>> PAGE_CACHE_SHIFT
);
433 pgoff_t indices
[PAGEVEC_SIZE
];
434 long nr_swaps_freed
= 0;
438 BUG_ON((lend
& (PAGE_CACHE_SIZE
- 1)) != (PAGE_CACHE_SIZE
- 1));
440 pagevec_init(&pvec
, 0);
442 while (index
<= end
) {
443 pvec
.nr
= shmem_find_get_pages_and_swap(mapping
, index
,
444 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
- 1) + 1,
445 pvec
.pages
, indices
);
448 mem_cgroup_uncharge_start();
449 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
450 struct page
*page
= pvec
.pages
[i
];
456 if (radix_tree_exceptional_entry(page
)) {
457 nr_swaps_freed
+= !shmem_free_swap(mapping
,
462 if (!trylock_page(page
))
464 if (page
->mapping
== mapping
) {
465 VM_BUG_ON(PageWriteback(page
));
466 truncate_inode_page(mapping
, page
);
470 shmem_pagevec_release(&pvec
);
471 mem_cgroup_uncharge_end();
477 struct page
*page
= NULL
;
478 shmem_getpage(inode
, start
- 1, &page
, SGP_READ
, NULL
);
480 zero_user_segment(page
, partial
, PAGE_CACHE_SIZE
);
481 set_page_dirty(page
);
483 page_cache_release(page
);
490 pvec
.nr
= shmem_find_get_pages_and_swap(mapping
, index
,
491 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
- 1) + 1,
492 pvec
.pages
, indices
);
499 if (index
== start
&& indices
[0] > end
) {
500 shmem_pagevec_release(&pvec
);
503 mem_cgroup_uncharge_start();
504 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
505 struct page
*page
= pvec
.pages
[i
];
511 if (radix_tree_exceptional_entry(page
)) {
512 nr_swaps_freed
+= !shmem_free_swap(mapping
,
518 if (page
->mapping
== mapping
) {
519 VM_BUG_ON(PageWriteback(page
));
520 truncate_inode_page(mapping
, page
);
524 shmem_pagevec_release(&pvec
);
525 mem_cgroup_uncharge_end();
529 spin_lock(&info
->lock
);
530 info
->swapped
-= nr_swaps_freed
;
531 shmem_recalc_inode(inode
);
532 spin_unlock(&info
->lock
);
534 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
536 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
538 static int shmem_setattr(struct dentry
*dentry
, struct iattr
*attr
)
540 struct inode
*inode
= dentry
->d_inode
;
543 error
= inode_change_ok(inode
, attr
);
547 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
548 loff_t oldsize
= inode
->i_size
;
549 loff_t newsize
= attr
->ia_size
;
551 if (newsize
!= oldsize
) {
552 i_size_write(inode
, newsize
);
553 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
555 if (newsize
< oldsize
) {
556 loff_t holebegin
= round_up(newsize
, PAGE_SIZE
);
557 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
558 shmem_truncate_range(inode
, newsize
, (loff_t
)-1);
559 /* unmap again to remove racily COWed private pages */
560 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
564 setattr_copy(inode
, attr
);
565 #ifdef CONFIG_TMPFS_POSIX_ACL
566 if (attr
->ia_valid
& ATTR_MODE
)
567 error
= generic_acl_chmod(inode
);
572 static void shmem_evict_inode(struct inode
*inode
)
574 struct shmem_inode_info
*info
= SHMEM_I(inode
);
575 struct shmem_xattr
*xattr
, *nxattr
;
577 if (inode
->i_mapping
->a_ops
== &shmem_aops
) {
578 shmem_unacct_size(info
->flags
, inode
->i_size
);
580 shmem_truncate_range(inode
, 0, (loff_t
)-1);
581 if (!list_empty(&info
->swaplist
)) {
582 mutex_lock(&shmem_swaplist_mutex
);
583 list_del_init(&info
->swaplist
);
584 mutex_unlock(&shmem_swaplist_mutex
);
588 list_for_each_entry_safe(xattr
, nxattr
, &info
->xattr_list
, list
) {
592 BUG_ON(inode
->i_blocks
);
593 shmem_free_inode(inode
->i_sb
);
594 end_writeback(inode
);
598 * If swap found in inode, free it and move page from swapcache to filecache.
600 static int shmem_unuse_inode(struct shmem_inode_info
*info
,
601 swp_entry_t swap
, struct page
*page
)
603 struct address_space
*mapping
= info
->vfs_inode
.i_mapping
;
608 radswap
= swp_to_radix_entry(swap
);
609 index
= shmem_find_swap(mapping
, radswap
);
614 * Move _head_ to start search for next from here.
615 * But be careful: shmem_evict_inode checks list_empty without taking
616 * mutex, and there's an instant in list_move_tail when info->swaplist
617 * would appear empty, if it were the only one on shmem_swaplist.
619 if (shmem_swaplist
.next
!= &info
->swaplist
)
620 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
623 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
624 * but also to hold up shmem_evict_inode(): so inode cannot be freed
625 * beneath us (pagelock doesn't help until the page is in pagecache).
627 error
= shmem_add_to_page_cache(page
, mapping
, index
,
628 GFP_NOWAIT
, radswap
);
629 /* which does mem_cgroup_uncharge_cache_page on error */
631 if (error
!= -ENOMEM
) {
633 * Truncation and eviction use free_swap_and_cache(), which
634 * only does trylock page: if we raced, best clean up here.
636 delete_from_swap_cache(page
);
637 set_page_dirty(page
);
639 spin_lock(&info
->lock
);
641 spin_unlock(&info
->lock
);
644 error
= 1; /* not an error, but entry was found */
650 * Search through swapped inodes to find and replace swap by page.
652 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
654 struct list_head
*this, *next
;
655 struct shmem_inode_info
*info
;
660 * Charge page using GFP_KERNEL while we can wait, before taking
661 * the shmem_swaplist_mutex which might hold up shmem_writepage().
662 * Charged back to the user (not to caller) when swap account is used.
663 * shmem_add_to_page_cache() will be called with GFP_NOWAIT.
665 error
= mem_cgroup_cache_charge(page
, current
->mm
, GFP_KERNEL
);
668 /* No radix_tree_preload: swap entry keeps a place for page in tree */
670 mutex_lock(&shmem_swaplist_mutex
);
671 list_for_each_safe(this, next
, &shmem_swaplist
) {
672 info
= list_entry(this, struct shmem_inode_info
, swaplist
);
673 if (!info
->swapped
) {
674 spin_lock(&info
->lock
);
676 list_del_init(&info
->swaplist
);
677 spin_unlock(&info
->lock
);
680 found
= shmem_unuse_inode(info
, swap
, page
);
685 mutex_unlock(&shmem_swaplist_mutex
);
688 mem_cgroup_uncharge_cache_page(page
);
693 page_cache_release(page
);
698 * Move the page from the page cache to the swap cache.
700 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
702 struct shmem_inode_info
*info
;
703 swp_entry_t swap
, oswap
;
704 struct address_space
*mapping
;
708 BUG_ON(!PageLocked(page
));
709 mapping
= page
->mapping
;
711 inode
= mapping
->host
;
712 info
= SHMEM_I(inode
);
713 if (info
->flags
& VM_LOCKED
)
715 if (!total_swap_pages
)
719 * shmem_backing_dev_info's capabilities prevent regular writeback or
720 * sync from ever calling shmem_writepage; but a stacking filesystem
721 * might use ->writepage of its underlying filesystem, in which case
722 * tmpfs should write out to swap only in response to memory pressure,
723 * and not for the writeback threads or sync.
725 if (!wbc
->for_reclaim
) {
726 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
731 * Disable even the toy swapping implementation, while we convert
732 * functions one by one to having swap entries in the radix tree.
734 if (index
< ULONG_MAX
)
737 swap
= get_swap_page();
742 * Add inode to shmem_unuse()'s list of swapped-out inodes,
743 * if it's not already there. Do it now because we cannot take
744 * mutex while holding spinlock, and must do so before the page
745 * is moved to swap cache, when its pagelock no longer protects
746 * the inode from eviction. But don't unlock the mutex until
747 * we've taken the spinlock, because shmem_unuse_inode() will
748 * prune a !swapped inode from the swaplist under both locks.
750 mutex_lock(&shmem_swaplist_mutex
);
751 if (list_empty(&info
->swaplist
))
752 list_add_tail(&info
->swaplist
, &shmem_swaplist
);
754 spin_lock(&info
->lock
);
755 mutex_unlock(&shmem_swaplist_mutex
);
757 oswap
= shmem_get_swap(info
, index
);
759 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
760 free_swap_and_cache(oswap
);
761 shmem_put_swap(info
, index
, (swp_entry_t
){0});
764 shmem_recalc_inode(inode
);
766 if (add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
767 delete_from_page_cache(page
);
768 shmem_put_swap(info
, index
, swap
);
770 swap_shmem_alloc(swap
);
771 spin_unlock(&info
->lock
);
772 BUG_ON(page_mapped(page
));
773 swap_writepage(page
, wbc
);
777 spin_unlock(&info
->lock
);
778 swapcache_free(swap
, NULL
);
780 set_page_dirty(page
);
781 if (wbc
->for_reclaim
)
782 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
789 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
793 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
794 return; /* show nothing */
796 mpol_to_str(buffer
, sizeof(buffer
), mpol
, 1);
798 seq_printf(seq
, ",mpol=%s", buffer
);
801 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
803 struct mempolicy
*mpol
= NULL
;
805 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
808 spin_unlock(&sbinfo
->stat_lock
);
812 #endif /* CONFIG_TMPFS */
814 static struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
815 struct shmem_inode_info
*info
, pgoff_t index
)
817 struct mempolicy mpol
, *spol
;
818 struct vm_area_struct pvma
;
820 spol
= mpol_cond_copy(&mpol
,
821 mpol_shared_policy_lookup(&info
->policy
, index
));
823 /* Create a pseudo vma that just contains the policy */
825 pvma
.vm_pgoff
= index
;
827 pvma
.vm_policy
= spol
;
828 return swapin_readahead(swap
, gfp
, &pvma
, 0);
831 static struct page
*shmem_alloc_page(gfp_t gfp
,
832 struct shmem_inode_info
*info
, pgoff_t index
)
834 struct vm_area_struct pvma
;
836 /* Create a pseudo vma that just contains the policy */
838 pvma
.vm_pgoff
= index
;
840 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, index
);
843 * alloc_page_vma() will drop the shared policy reference
845 return alloc_page_vma(gfp
, &pvma
, 0);
847 #else /* !CONFIG_NUMA */
849 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
852 #endif /* CONFIG_TMPFS */
854 static inline struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
855 struct shmem_inode_info
*info
, pgoff_t index
)
857 return swapin_readahead(swap
, gfp
, NULL
, 0);
860 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
861 struct shmem_inode_info
*info
, pgoff_t index
)
863 return alloc_page(gfp
);
865 #endif /* CONFIG_NUMA */
867 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
868 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
875 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
877 * If we allocate a new one we do not mark it dirty. That's up to the
878 * vm. If we swap it in we mark it dirty since we also free the swap
879 * entry since a page cannot live in both the swap and page cache
881 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
882 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
)
884 struct address_space
*mapping
= inode
->i_mapping
;
885 struct shmem_inode_info
*info
;
886 struct shmem_sb_info
*sbinfo
;
892 if (index
> (MAX_LFS_FILESIZE
>> PAGE_CACHE_SHIFT
))
896 page
= find_lock_page(mapping
, index
);
897 if (radix_tree_exceptional_entry(page
)) {
898 swap
= radix_to_swp_entry(page
);
902 if (sgp
!= SGP_WRITE
&&
903 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
908 if (page
|| (sgp
== SGP_READ
&& !swap
.val
)) {
910 * Once we can get the page lock, it must be uptodate:
911 * if there were an error in reading back from swap,
912 * the page would not be inserted into the filecache.
914 BUG_ON(page
&& !PageUptodate(page
));
920 * Fast cache lookup did not find it:
921 * bring it back from swap or allocate.
923 info
= SHMEM_I(inode
);
924 sbinfo
= SHMEM_SB(inode
->i_sb
);
927 /* Look it up and read it in.. */
928 page
= lookup_swap_cache(swap
);
930 /* here we actually do the io */
932 *fault_type
|= VM_FAULT_MAJOR
;
933 page
= shmem_swapin(swap
, gfp
, info
, index
);
940 /* We have to do this with page locked to prevent races */
942 if (!PageUptodate(page
)) {
946 wait_on_page_writeback(page
);
948 /* Someone may have already done it for us */
950 if (page
->mapping
== mapping
&&
951 page
->index
== index
)
957 error
= shmem_add_to_page_cache(page
, mapping
, index
,
958 gfp
, swp_to_radix_entry(swap
));
962 spin_lock(&info
->lock
);
964 shmem_recalc_inode(inode
);
965 spin_unlock(&info
->lock
);
967 delete_from_swap_cache(page
);
968 set_page_dirty(page
);
972 if (shmem_acct_block(info
->flags
)) {
976 if (sbinfo
->max_blocks
) {
977 if (percpu_counter_compare(&sbinfo
->used_blocks
,
978 sbinfo
->max_blocks
) >= 0) {
982 percpu_counter_inc(&sbinfo
->used_blocks
);
985 page
= shmem_alloc_page(gfp
, info
, index
);
991 SetPageSwapBacked(page
);
992 __set_page_locked(page
);
993 error
= shmem_add_to_page_cache(page
, mapping
, index
,
997 lru_cache_add_anon(page
);
999 spin_lock(&info
->lock
);
1001 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1002 shmem_recalc_inode(inode
);
1003 spin_unlock(&info
->lock
);
1005 clear_highpage(page
);
1006 flush_dcache_page(page
);
1007 SetPageUptodate(page
);
1008 if (sgp
== SGP_DIRTY
)
1009 set_page_dirty(page
);
1012 /* Perhaps the file has been truncated since we checked */
1013 if (sgp
!= SGP_WRITE
&&
1014 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1025 ClearPageDirty(page
);
1026 delete_from_page_cache(page
);
1027 spin_lock(&info
->lock
);
1029 inode
->i_blocks
-= BLOCKS_PER_PAGE
;
1030 spin_unlock(&info
->lock
);
1032 if (sbinfo
->max_blocks
)
1033 percpu_counter_add(&sbinfo
->used_blocks
, -1);
1035 shmem_unacct_blocks(info
->flags
, 1);
1037 if (swap
.val
&& error
!= -EINVAL
) {
1038 struct page
*test
= find_get_page(mapping
, index
);
1039 if (test
&& !radix_tree_exceptional_entry(test
))
1040 page_cache_release(test
);
1041 /* Have another try if the entry has changed */
1042 if (test
!= swp_to_radix_entry(swap
))
1047 page_cache_release(page
);
1049 if (error
== -ENOSPC
&& !once
++) {
1050 info
= SHMEM_I(inode
);
1051 spin_lock(&info
->lock
);
1052 shmem_recalc_inode(inode
);
1053 spin_unlock(&info
->lock
);
1056 if (error
== -EEXIST
)
1061 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1063 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1065 int ret
= VM_FAULT_LOCKED
;
1067 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1069 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1071 if (ret
& VM_FAULT_MAJOR
) {
1072 count_vm_event(PGMAJFAULT
);
1073 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1079 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*mpol
)
1081 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1082 return mpol_set_shared_policy(&SHMEM_I(inode
)->policy
, vma
, mpol
);
1085 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1088 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1091 index
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1092 return mpol_shared_policy_lookup(&SHMEM_I(inode
)->policy
, index
);
1096 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1098 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1099 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1100 int retval
= -ENOMEM
;
1102 spin_lock(&info
->lock
);
1103 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1104 if (!user_shm_lock(inode
->i_size
, user
))
1106 info
->flags
|= VM_LOCKED
;
1107 mapping_set_unevictable(file
->f_mapping
);
1109 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1110 user_shm_unlock(inode
->i_size
, user
);
1111 info
->flags
&= ~VM_LOCKED
;
1112 mapping_clear_unevictable(file
->f_mapping
);
1113 scan_mapping_unevictable_pages(file
->f_mapping
);
1118 spin_unlock(&info
->lock
);
1122 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1124 file_accessed(file
);
1125 vma
->vm_ops
= &shmem_vm_ops
;
1126 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1130 static struct inode
*shmem_get_inode(struct super_block
*sb
, const struct inode
*dir
,
1131 int mode
, dev_t dev
, unsigned long flags
)
1133 struct inode
*inode
;
1134 struct shmem_inode_info
*info
;
1135 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1137 if (shmem_reserve_inode(sb
))
1140 inode
= new_inode(sb
);
1142 inode
->i_ino
= get_next_ino();
1143 inode_init_owner(inode
, dir
, mode
);
1144 inode
->i_blocks
= 0;
1145 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1146 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1147 inode
->i_generation
= get_seconds();
1148 info
= SHMEM_I(inode
);
1149 memset(info
, 0, (char *)inode
- (char *)info
);
1150 spin_lock_init(&info
->lock
);
1151 info
->flags
= flags
& VM_NORESERVE
;
1152 INIT_LIST_HEAD(&info
->swaplist
);
1153 INIT_LIST_HEAD(&info
->xattr_list
);
1154 cache_no_acl(inode
);
1156 switch (mode
& S_IFMT
) {
1158 inode
->i_op
= &shmem_special_inode_operations
;
1159 init_special_inode(inode
, mode
, dev
);
1162 inode
->i_mapping
->a_ops
= &shmem_aops
;
1163 inode
->i_op
= &shmem_inode_operations
;
1164 inode
->i_fop
= &shmem_file_operations
;
1165 mpol_shared_policy_init(&info
->policy
,
1166 shmem_get_sbmpol(sbinfo
));
1170 /* Some things misbehave if size == 0 on a directory */
1171 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1172 inode
->i_op
= &shmem_dir_inode_operations
;
1173 inode
->i_fop
= &simple_dir_operations
;
1177 * Must not load anything in the rbtree,
1178 * mpol_free_shared_policy will not be called.
1180 mpol_shared_policy_init(&info
->policy
, NULL
);
1184 shmem_free_inode(sb
);
1189 static const struct inode_operations shmem_symlink_inode_operations
;
1190 static const struct inode_operations shmem_symlink_inline_operations
;
1193 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1194 loff_t pos
, unsigned len
, unsigned flags
,
1195 struct page
**pagep
, void **fsdata
)
1197 struct inode
*inode
= mapping
->host
;
1198 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1199 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1203 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1204 loff_t pos
, unsigned len
, unsigned copied
,
1205 struct page
*page
, void *fsdata
)
1207 struct inode
*inode
= mapping
->host
;
1209 if (pos
+ copied
> inode
->i_size
)
1210 i_size_write(inode
, pos
+ copied
);
1212 set_page_dirty(page
);
1214 page_cache_release(page
);
1219 static void do_shmem_file_read(struct file
*filp
, loff_t
*ppos
, read_descriptor_t
*desc
, read_actor_t actor
)
1221 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
1222 struct address_space
*mapping
= inode
->i_mapping
;
1224 unsigned long offset
;
1225 enum sgp_type sgp
= SGP_READ
;
1228 * Might this read be for a stacking filesystem? Then when reading
1229 * holes of a sparse file, we actually need to allocate those pages,
1230 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1232 if (segment_eq(get_fs(), KERNEL_DS
))
1235 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1236 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1239 struct page
*page
= NULL
;
1241 unsigned long nr
, ret
;
1242 loff_t i_size
= i_size_read(inode
);
1244 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1245 if (index
> end_index
)
1247 if (index
== end_index
) {
1248 nr
= i_size
& ~PAGE_CACHE_MASK
;
1253 desc
->error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1255 if (desc
->error
== -EINVAL
)
1263 * We must evaluate after, since reads (unlike writes)
1264 * are called without i_mutex protection against truncate
1266 nr
= PAGE_CACHE_SIZE
;
1267 i_size
= i_size_read(inode
);
1268 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1269 if (index
== end_index
) {
1270 nr
= i_size
& ~PAGE_CACHE_MASK
;
1273 page_cache_release(page
);
1281 * If users can be writing to this page using arbitrary
1282 * virtual addresses, take care about potential aliasing
1283 * before reading the page on the kernel side.
1285 if (mapping_writably_mapped(mapping
))
1286 flush_dcache_page(page
);
1288 * Mark the page accessed if we read the beginning.
1291 mark_page_accessed(page
);
1293 page
= ZERO_PAGE(0);
1294 page_cache_get(page
);
1298 * Ok, we have the page, and it's up-to-date, so
1299 * now we can copy it to user space...
1301 * The actor routine returns how many bytes were actually used..
1302 * NOTE! This may not be the same as how much of a user buffer
1303 * we filled up (we may be padding etc), so we can only update
1304 * "pos" here (the actor routine has to update the user buffer
1305 * pointers and the remaining count).
1307 ret
= actor(desc
, page
, offset
, nr
);
1309 index
+= offset
>> PAGE_CACHE_SHIFT
;
1310 offset
&= ~PAGE_CACHE_MASK
;
1312 page_cache_release(page
);
1313 if (ret
!= nr
|| !desc
->count
)
1319 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1320 file_accessed(filp
);
1323 static ssize_t
shmem_file_aio_read(struct kiocb
*iocb
,
1324 const struct iovec
*iov
, unsigned long nr_segs
, loff_t pos
)
1326 struct file
*filp
= iocb
->ki_filp
;
1330 loff_t
*ppos
= &iocb
->ki_pos
;
1332 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1336 for (seg
= 0; seg
< nr_segs
; seg
++) {
1337 read_descriptor_t desc
;
1340 desc
.arg
.buf
= iov
[seg
].iov_base
;
1341 desc
.count
= iov
[seg
].iov_len
;
1342 if (desc
.count
== 0)
1345 do_shmem_file_read(filp
, ppos
, &desc
, file_read_actor
);
1346 retval
+= desc
.written
;
1348 retval
= retval
?: desc
.error
;
1357 static ssize_t
shmem_file_splice_read(struct file
*in
, loff_t
*ppos
,
1358 struct pipe_inode_info
*pipe
, size_t len
,
1361 struct address_space
*mapping
= in
->f_mapping
;
1362 struct inode
*inode
= mapping
->host
;
1363 unsigned int loff
, nr_pages
, req_pages
;
1364 struct page
*pages
[PIPE_DEF_BUFFERS
];
1365 struct partial_page partial
[PIPE_DEF_BUFFERS
];
1367 pgoff_t index
, end_index
;
1370 struct splice_pipe_desc spd
= {
1374 .ops
= &page_cache_pipe_buf_ops
,
1375 .spd_release
= spd_release_page
,
1378 isize
= i_size_read(inode
);
1379 if (unlikely(*ppos
>= isize
))
1382 left
= isize
- *ppos
;
1383 if (unlikely(left
< len
))
1386 if (splice_grow_spd(pipe
, &spd
))
1389 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1390 loff
= *ppos
& ~PAGE_CACHE_MASK
;
1391 req_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1392 nr_pages
= min(req_pages
, pipe
->buffers
);
1394 spd
.nr_pages
= find_get_pages_contig(mapping
, index
,
1395 nr_pages
, spd
.pages
);
1396 index
+= spd
.nr_pages
;
1399 while (spd
.nr_pages
< nr_pages
) {
1400 error
= shmem_getpage(inode
, index
, &page
, SGP_CACHE
, NULL
);
1404 spd
.pages
[spd
.nr_pages
++] = page
;
1408 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1409 nr_pages
= spd
.nr_pages
;
1412 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
1413 unsigned int this_len
;
1418 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
1419 page
= spd
.pages
[page_nr
];
1421 if (!PageUptodate(page
) || page
->mapping
!= mapping
) {
1422 error
= shmem_getpage(inode
, index
, &page
,
1427 page_cache_release(spd
.pages
[page_nr
]);
1428 spd
.pages
[page_nr
] = page
;
1431 isize
= i_size_read(inode
);
1432 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1433 if (unlikely(!isize
|| index
> end_index
))
1436 if (end_index
== index
) {
1439 plen
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1443 this_len
= min(this_len
, plen
- loff
);
1447 spd
.partial
[page_nr
].offset
= loff
;
1448 spd
.partial
[page_nr
].len
= this_len
;
1455 while (page_nr
< nr_pages
)
1456 page_cache_release(spd
.pages
[page_nr
++]);
1459 error
= splice_to_pipe(pipe
, &spd
);
1461 splice_shrink_spd(pipe
, &spd
);
1470 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1472 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1474 buf
->f_type
= TMPFS_MAGIC
;
1475 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1476 buf
->f_namelen
= NAME_MAX
;
1477 if (sbinfo
->max_blocks
) {
1478 buf
->f_blocks
= sbinfo
->max_blocks
;
1480 buf
->f_bfree
= sbinfo
->max_blocks
-
1481 percpu_counter_sum(&sbinfo
->used_blocks
);
1483 if (sbinfo
->max_inodes
) {
1484 buf
->f_files
= sbinfo
->max_inodes
;
1485 buf
->f_ffree
= sbinfo
->free_inodes
;
1487 /* else leave those fields 0 like simple_statfs */
1492 * File creation. Allocate an inode, and we're done..
1495 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1497 struct inode
*inode
;
1498 int error
= -ENOSPC
;
1500 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, dev
, VM_NORESERVE
);
1502 error
= security_inode_init_security(inode
, dir
,
1503 &dentry
->d_name
, NULL
,
1506 if (error
!= -EOPNOTSUPP
) {
1511 #ifdef CONFIG_TMPFS_POSIX_ACL
1512 error
= generic_acl_init(inode
, dir
);
1520 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1521 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1522 d_instantiate(dentry
, inode
);
1523 dget(dentry
); /* Extra count - pin the dentry in core */
1528 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
1532 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1538 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1539 struct nameidata
*nd
)
1541 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
1547 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
1549 struct inode
*inode
= old_dentry
->d_inode
;
1553 * No ordinary (disk based) filesystem counts links as inodes;
1554 * but each new link needs a new dentry, pinning lowmem, and
1555 * tmpfs dentries cannot be pruned until they are unlinked.
1557 ret
= shmem_reserve_inode(inode
->i_sb
);
1561 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1562 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1564 ihold(inode
); /* New dentry reference */
1565 dget(dentry
); /* Extra pinning count for the created dentry */
1566 d_instantiate(dentry
, inode
);
1571 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
1573 struct inode
*inode
= dentry
->d_inode
;
1575 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
1576 shmem_free_inode(inode
->i_sb
);
1578 dir
->i_size
-= BOGO_DIRENT_SIZE
;
1579 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1581 dput(dentry
); /* Undo the count from "create" - this does all the work */
1585 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1587 if (!simple_empty(dentry
))
1590 drop_nlink(dentry
->d_inode
);
1592 return shmem_unlink(dir
, dentry
);
1596 * The VFS layer already does all the dentry stuff for rename,
1597 * we just have to decrement the usage count for the target if
1598 * it exists so that the VFS layer correctly free's it when it
1601 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
1603 struct inode
*inode
= old_dentry
->d_inode
;
1604 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
1606 if (!simple_empty(new_dentry
))
1609 if (new_dentry
->d_inode
) {
1610 (void) shmem_unlink(new_dir
, new_dentry
);
1612 drop_nlink(old_dir
);
1613 } else if (they_are_dirs
) {
1614 drop_nlink(old_dir
);
1618 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
1619 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
1620 old_dir
->i_ctime
= old_dir
->i_mtime
=
1621 new_dir
->i_ctime
= new_dir
->i_mtime
=
1622 inode
->i_ctime
= CURRENT_TIME
;
1626 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
1630 struct inode
*inode
;
1633 struct shmem_inode_info
*info
;
1635 len
= strlen(symname
) + 1;
1636 if (len
> PAGE_CACHE_SIZE
)
1637 return -ENAMETOOLONG
;
1639 inode
= shmem_get_inode(dir
->i_sb
, dir
, S_IFLNK
|S_IRWXUGO
, 0, VM_NORESERVE
);
1643 error
= security_inode_init_security(inode
, dir
, &dentry
->d_name
, NULL
,
1646 if (error
!= -EOPNOTSUPP
) {
1653 info
= SHMEM_I(inode
);
1654 inode
->i_size
= len
-1;
1655 if (len
<= SHMEM_SYMLINK_INLINE_LEN
) {
1657 memcpy(info
->inline_symlink
, symname
, len
);
1658 inode
->i_op
= &shmem_symlink_inline_operations
;
1660 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
1665 inode
->i_mapping
->a_ops
= &shmem_aops
;
1666 inode
->i_op
= &shmem_symlink_inode_operations
;
1667 kaddr
= kmap_atomic(page
, KM_USER0
);
1668 memcpy(kaddr
, symname
, len
);
1669 kunmap_atomic(kaddr
, KM_USER0
);
1670 set_page_dirty(page
);
1672 page_cache_release(page
);
1674 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1675 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1676 d_instantiate(dentry
, inode
);
1681 static void *shmem_follow_link_inline(struct dentry
*dentry
, struct nameidata
*nd
)
1683 nd_set_link(nd
, SHMEM_I(dentry
->d_inode
)->inline_symlink
);
1687 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
1689 struct page
*page
= NULL
;
1690 int error
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
1691 nd_set_link(nd
, error
? ERR_PTR(error
) : kmap(page
));
1697 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
1699 if (!IS_ERR(nd_get_link(nd
))) {
1700 struct page
*page
= cookie
;
1702 mark_page_accessed(page
);
1703 page_cache_release(page
);
1707 #ifdef CONFIG_TMPFS_XATTR
1709 * Superblocks without xattr inode operations may get some security.* xattr
1710 * support from the LSM "for free". As soon as we have any other xattrs
1711 * like ACLs, we also need to implement the security.* handlers at
1712 * filesystem level, though.
1715 static int shmem_xattr_get(struct dentry
*dentry
, const char *name
,
1716 void *buffer
, size_t size
)
1718 struct shmem_inode_info
*info
;
1719 struct shmem_xattr
*xattr
;
1722 info
= SHMEM_I(dentry
->d_inode
);
1724 spin_lock(&info
->lock
);
1725 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
1726 if (strcmp(name
, xattr
->name
))
1731 if (size
< xattr
->size
)
1734 memcpy(buffer
, xattr
->value
, xattr
->size
);
1738 spin_unlock(&info
->lock
);
1742 static int shmem_xattr_set(struct dentry
*dentry
, const char *name
,
1743 const void *value
, size_t size
, int flags
)
1745 struct inode
*inode
= dentry
->d_inode
;
1746 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1747 struct shmem_xattr
*xattr
;
1748 struct shmem_xattr
*new_xattr
= NULL
;
1752 /* value == NULL means remove */
1755 len
= sizeof(*new_xattr
) + size
;
1756 if (len
<= sizeof(*new_xattr
))
1759 new_xattr
= kmalloc(len
, GFP_KERNEL
);
1763 new_xattr
->name
= kstrdup(name
, GFP_KERNEL
);
1764 if (!new_xattr
->name
) {
1769 new_xattr
->size
= size
;
1770 memcpy(new_xattr
->value
, value
, size
);
1773 spin_lock(&info
->lock
);
1774 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
1775 if (!strcmp(name
, xattr
->name
)) {
1776 if (flags
& XATTR_CREATE
) {
1779 } else if (new_xattr
) {
1780 list_replace(&xattr
->list
, &new_xattr
->list
);
1782 list_del(&xattr
->list
);
1787 if (flags
& XATTR_REPLACE
) {
1791 list_add(&new_xattr
->list
, &info
->xattr_list
);
1795 spin_unlock(&info
->lock
);
1802 static const struct xattr_handler
*shmem_xattr_handlers
[] = {
1803 #ifdef CONFIG_TMPFS_POSIX_ACL
1804 &generic_acl_access_handler
,
1805 &generic_acl_default_handler
,
1810 static int shmem_xattr_validate(const char *name
)
1812 struct { const char *prefix
; size_t len
; } arr
[] = {
1813 { XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
},
1814 { XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
}
1818 for (i
= 0; i
< ARRAY_SIZE(arr
); i
++) {
1819 size_t preflen
= arr
[i
].len
;
1820 if (strncmp(name
, arr
[i
].prefix
, preflen
) == 0) {
1829 static ssize_t
shmem_getxattr(struct dentry
*dentry
, const char *name
,
1830 void *buffer
, size_t size
)
1835 * If this is a request for a synthetic attribute in the system.*
1836 * namespace use the generic infrastructure to resolve a handler
1837 * for it via sb->s_xattr.
1839 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
1840 return generic_getxattr(dentry
, name
, buffer
, size
);
1842 err
= shmem_xattr_validate(name
);
1846 return shmem_xattr_get(dentry
, name
, buffer
, size
);
1849 static int shmem_setxattr(struct dentry
*dentry
, const char *name
,
1850 const void *value
, size_t size
, int flags
)
1855 * If this is a request for a synthetic attribute in the system.*
1856 * namespace use the generic infrastructure to resolve a handler
1857 * for it via sb->s_xattr.
1859 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
1860 return generic_setxattr(dentry
, name
, value
, size
, flags
);
1862 err
= shmem_xattr_validate(name
);
1867 value
= ""; /* empty EA, do not remove */
1869 return shmem_xattr_set(dentry
, name
, value
, size
, flags
);
1873 static int shmem_removexattr(struct dentry
*dentry
, const char *name
)
1878 * If this is a request for a synthetic attribute in the system.*
1879 * namespace use the generic infrastructure to resolve a handler
1880 * for it via sb->s_xattr.
1882 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
1883 return generic_removexattr(dentry
, name
);
1885 err
= shmem_xattr_validate(name
);
1889 return shmem_xattr_set(dentry
, name
, NULL
, 0, XATTR_REPLACE
);
1892 static bool xattr_is_trusted(const char *name
)
1894 return !strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
);
1897 static ssize_t
shmem_listxattr(struct dentry
*dentry
, char *buffer
, size_t size
)
1899 bool trusted
= capable(CAP_SYS_ADMIN
);
1900 struct shmem_xattr
*xattr
;
1901 struct shmem_inode_info
*info
;
1904 info
= SHMEM_I(dentry
->d_inode
);
1906 spin_lock(&info
->lock
);
1907 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
1910 /* skip "trusted." attributes for unprivileged callers */
1911 if (!trusted
&& xattr_is_trusted(xattr
->name
))
1914 len
= strlen(xattr
->name
) + 1;
1921 memcpy(buffer
, xattr
->name
, len
);
1925 spin_unlock(&info
->lock
);
1929 #endif /* CONFIG_TMPFS_XATTR */
1931 static const struct inode_operations shmem_symlink_inline_operations
= {
1932 .readlink
= generic_readlink
,
1933 .follow_link
= shmem_follow_link_inline
,
1934 #ifdef CONFIG_TMPFS_XATTR
1935 .setxattr
= shmem_setxattr
,
1936 .getxattr
= shmem_getxattr
,
1937 .listxattr
= shmem_listxattr
,
1938 .removexattr
= shmem_removexattr
,
1942 static const struct inode_operations shmem_symlink_inode_operations
= {
1943 .readlink
= generic_readlink
,
1944 .follow_link
= shmem_follow_link
,
1945 .put_link
= shmem_put_link
,
1946 #ifdef CONFIG_TMPFS_XATTR
1947 .setxattr
= shmem_setxattr
,
1948 .getxattr
= shmem_getxattr
,
1949 .listxattr
= shmem_listxattr
,
1950 .removexattr
= shmem_removexattr
,
1954 static struct dentry
*shmem_get_parent(struct dentry
*child
)
1956 return ERR_PTR(-ESTALE
);
1959 static int shmem_match(struct inode
*ino
, void *vfh
)
1963 inum
= (inum
<< 32) | fh
[1];
1964 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
1967 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
1968 struct fid
*fid
, int fh_len
, int fh_type
)
1970 struct inode
*inode
;
1971 struct dentry
*dentry
= NULL
;
1972 u64 inum
= fid
->raw
[2];
1973 inum
= (inum
<< 32) | fid
->raw
[1];
1978 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
1979 shmem_match
, fid
->raw
);
1981 dentry
= d_find_alias(inode
);
1988 static int shmem_encode_fh(struct dentry
*dentry
, __u32
*fh
, int *len
,
1991 struct inode
*inode
= dentry
->d_inode
;
1998 if (inode_unhashed(inode
)) {
1999 /* Unfortunately insert_inode_hash is not idempotent,
2000 * so as we hash inodes here rather than at creation
2001 * time, we need a lock to ensure we only try
2004 static DEFINE_SPINLOCK(lock
);
2006 if (inode_unhashed(inode
))
2007 __insert_inode_hash(inode
,
2008 inode
->i_ino
+ inode
->i_generation
);
2012 fh
[0] = inode
->i_generation
;
2013 fh
[1] = inode
->i_ino
;
2014 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2020 static const struct export_operations shmem_export_ops
= {
2021 .get_parent
= shmem_get_parent
,
2022 .encode_fh
= shmem_encode_fh
,
2023 .fh_to_dentry
= shmem_fh_to_dentry
,
2026 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2029 char *this_char
, *value
, *rest
;
2031 while (options
!= NULL
) {
2032 this_char
= options
;
2035 * NUL-terminate this option: unfortunately,
2036 * mount options form a comma-separated list,
2037 * but mpol's nodelist may also contain commas.
2039 options
= strchr(options
, ',');
2040 if (options
== NULL
)
2043 if (!isdigit(*options
)) {
2050 if ((value
= strchr(this_char
,'=')) != NULL
) {
2054 "tmpfs: No value for mount option '%s'\n",
2059 if (!strcmp(this_char
,"size")) {
2060 unsigned long long size
;
2061 size
= memparse(value
,&rest
);
2063 size
<<= PAGE_SHIFT
;
2064 size
*= totalram_pages
;
2070 sbinfo
->max_blocks
=
2071 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2072 } else if (!strcmp(this_char
,"nr_blocks")) {
2073 sbinfo
->max_blocks
= memparse(value
, &rest
);
2076 } else if (!strcmp(this_char
,"nr_inodes")) {
2077 sbinfo
->max_inodes
= memparse(value
, &rest
);
2080 } else if (!strcmp(this_char
,"mode")) {
2083 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2086 } else if (!strcmp(this_char
,"uid")) {
2089 sbinfo
->uid
= simple_strtoul(value
, &rest
, 0);
2092 } else if (!strcmp(this_char
,"gid")) {
2095 sbinfo
->gid
= simple_strtoul(value
, &rest
, 0);
2098 } else if (!strcmp(this_char
,"mpol")) {
2099 if (mpol_parse_str(value
, &sbinfo
->mpol
, 1))
2102 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2110 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2116 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2118 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2119 struct shmem_sb_info config
= *sbinfo
;
2120 unsigned long inodes
;
2121 int error
= -EINVAL
;
2123 if (shmem_parse_options(data
, &config
, true))
2126 spin_lock(&sbinfo
->stat_lock
);
2127 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2128 if (percpu_counter_compare(&sbinfo
->used_blocks
, config
.max_blocks
) > 0)
2130 if (config
.max_inodes
< inodes
)
2133 * Those tests disallow limited->unlimited while any are in use;
2134 * but we must separately disallow unlimited->limited, because
2135 * in that case we have no record of how much is already in use.
2137 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2139 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2143 sbinfo
->max_blocks
= config
.max_blocks
;
2144 sbinfo
->max_inodes
= config
.max_inodes
;
2145 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2147 mpol_put(sbinfo
->mpol
);
2148 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2150 spin_unlock(&sbinfo
->stat_lock
);
2154 static int shmem_show_options(struct seq_file
*seq
, struct vfsmount
*vfs
)
2156 struct shmem_sb_info
*sbinfo
= SHMEM_SB(vfs
->mnt_sb
);
2158 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2159 seq_printf(seq
, ",size=%luk",
2160 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2161 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2162 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2163 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2164 seq_printf(seq
, ",mode=%03o", sbinfo
->mode
);
2165 if (sbinfo
->uid
!= 0)
2166 seq_printf(seq
, ",uid=%u", sbinfo
->uid
);
2167 if (sbinfo
->gid
!= 0)
2168 seq_printf(seq
, ",gid=%u", sbinfo
->gid
);
2169 shmem_show_mpol(seq
, sbinfo
->mpol
);
2172 #endif /* CONFIG_TMPFS */
2174 static void shmem_put_super(struct super_block
*sb
)
2176 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2178 percpu_counter_destroy(&sbinfo
->used_blocks
);
2180 sb
->s_fs_info
= NULL
;
2183 int shmem_fill_super(struct super_block
*sb
, void *data
, int silent
)
2185 struct inode
*inode
;
2186 struct dentry
*root
;
2187 struct shmem_sb_info
*sbinfo
;
2190 /* Round up to L1_CACHE_BYTES to resist false sharing */
2191 sbinfo
= kzalloc(max((int)sizeof(struct shmem_sb_info
),
2192 L1_CACHE_BYTES
), GFP_KERNEL
);
2196 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2197 sbinfo
->uid
= current_fsuid();
2198 sbinfo
->gid
= current_fsgid();
2199 sb
->s_fs_info
= sbinfo
;
2203 * Per default we only allow half of the physical ram per
2204 * tmpfs instance, limiting inodes to one per page of lowmem;
2205 * but the internal instance is left unlimited.
2207 if (!(sb
->s_flags
& MS_NOUSER
)) {
2208 sbinfo
->max_blocks
= shmem_default_max_blocks();
2209 sbinfo
->max_inodes
= shmem_default_max_inodes();
2210 if (shmem_parse_options(data
, sbinfo
, false)) {
2215 sb
->s_export_op
= &shmem_export_ops
;
2217 sb
->s_flags
|= MS_NOUSER
;
2220 spin_lock_init(&sbinfo
->stat_lock
);
2221 if (percpu_counter_init(&sbinfo
->used_blocks
, 0))
2223 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2225 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
2226 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2227 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2228 sb
->s_magic
= TMPFS_MAGIC
;
2229 sb
->s_op
= &shmem_ops
;
2230 sb
->s_time_gran
= 1;
2231 #ifdef CONFIG_TMPFS_XATTR
2232 sb
->s_xattr
= shmem_xattr_handlers
;
2234 #ifdef CONFIG_TMPFS_POSIX_ACL
2235 sb
->s_flags
|= MS_POSIXACL
;
2238 inode
= shmem_get_inode(sb
, NULL
, S_IFDIR
| sbinfo
->mode
, 0, VM_NORESERVE
);
2241 inode
->i_uid
= sbinfo
->uid
;
2242 inode
->i_gid
= sbinfo
->gid
;
2243 root
= d_alloc_root(inode
);
2252 shmem_put_super(sb
);
2256 static struct kmem_cache
*shmem_inode_cachep
;
2258 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2260 struct shmem_inode_info
*info
;
2261 info
= kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2264 return &info
->vfs_inode
;
2267 static void shmem_destroy_callback(struct rcu_head
*head
)
2269 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
2270 INIT_LIST_HEAD(&inode
->i_dentry
);
2271 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2274 static void shmem_destroy_inode(struct inode
*inode
)
2276 if ((inode
->i_mode
& S_IFMT
) == S_IFREG
) {
2277 /* only struct inode is valid if it's an inline symlink */
2278 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2280 call_rcu(&inode
->i_rcu
, shmem_destroy_callback
);
2283 static void shmem_init_inode(void *foo
)
2285 struct shmem_inode_info
*info
= foo
;
2286 inode_init_once(&info
->vfs_inode
);
2289 static int shmem_init_inodecache(void)
2291 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2292 sizeof(struct shmem_inode_info
),
2293 0, SLAB_PANIC
, shmem_init_inode
);
2297 static void shmem_destroy_inodecache(void)
2299 kmem_cache_destroy(shmem_inode_cachep
);
2302 static const struct address_space_operations shmem_aops
= {
2303 .writepage
= shmem_writepage
,
2304 .set_page_dirty
= __set_page_dirty_no_writeback
,
2306 .write_begin
= shmem_write_begin
,
2307 .write_end
= shmem_write_end
,
2309 .migratepage
= migrate_page
,
2310 .error_remove_page
= generic_error_remove_page
,
2313 static const struct file_operations shmem_file_operations
= {
2316 .llseek
= generic_file_llseek
,
2317 .read
= do_sync_read
,
2318 .write
= do_sync_write
,
2319 .aio_read
= shmem_file_aio_read
,
2320 .aio_write
= generic_file_aio_write
,
2321 .fsync
= noop_fsync
,
2322 .splice_read
= shmem_file_splice_read
,
2323 .splice_write
= generic_file_splice_write
,
2327 static const struct inode_operations shmem_inode_operations
= {
2328 .setattr
= shmem_setattr
,
2329 .truncate_range
= shmem_truncate_range
,
2330 #ifdef CONFIG_TMPFS_XATTR
2331 .setxattr
= shmem_setxattr
,
2332 .getxattr
= shmem_getxattr
,
2333 .listxattr
= shmem_listxattr
,
2334 .removexattr
= shmem_removexattr
,
2338 static const struct inode_operations shmem_dir_inode_operations
= {
2340 .create
= shmem_create
,
2341 .lookup
= simple_lookup
,
2343 .unlink
= shmem_unlink
,
2344 .symlink
= shmem_symlink
,
2345 .mkdir
= shmem_mkdir
,
2346 .rmdir
= shmem_rmdir
,
2347 .mknod
= shmem_mknod
,
2348 .rename
= shmem_rename
,
2350 #ifdef CONFIG_TMPFS_XATTR
2351 .setxattr
= shmem_setxattr
,
2352 .getxattr
= shmem_getxattr
,
2353 .listxattr
= shmem_listxattr
,
2354 .removexattr
= shmem_removexattr
,
2356 #ifdef CONFIG_TMPFS_POSIX_ACL
2357 .setattr
= shmem_setattr
,
2361 static const struct inode_operations shmem_special_inode_operations
= {
2362 #ifdef CONFIG_TMPFS_XATTR
2363 .setxattr
= shmem_setxattr
,
2364 .getxattr
= shmem_getxattr
,
2365 .listxattr
= shmem_listxattr
,
2366 .removexattr
= shmem_removexattr
,
2368 #ifdef CONFIG_TMPFS_POSIX_ACL
2369 .setattr
= shmem_setattr
,
2373 static const struct super_operations shmem_ops
= {
2374 .alloc_inode
= shmem_alloc_inode
,
2375 .destroy_inode
= shmem_destroy_inode
,
2377 .statfs
= shmem_statfs
,
2378 .remount_fs
= shmem_remount_fs
,
2379 .show_options
= shmem_show_options
,
2381 .evict_inode
= shmem_evict_inode
,
2382 .drop_inode
= generic_delete_inode
,
2383 .put_super
= shmem_put_super
,
2386 static const struct vm_operations_struct shmem_vm_ops
= {
2387 .fault
= shmem_fault
,
2389 .set_policy
= shmem_set_policy
,
2390 .get_policy
= shmem_get_policy
,
2394 static struct dentry
*shmem_mount(struct file_system_type
*fs_type
,
2395 int flags
, const char *dev_name
, void *data
)
2397 return mount_nodev(fs_type
, flags
, data
, shmem_fill_super
);
2400 static struct file_system_type shmem_fs_type
= {
2401 .owner
= THIS_MODULE
,
2403 .mount
= shmem_mount
,
2404 .kill_sb
= kill_litter_super
,
2407 int __init
shmem_init(void)
2411 error
= bdi_init(&shmem_backing_dev_info
);
2415 error
= shmem_init_inodecache();
2419 error
= register_filesystem(&shmem_fs_type
);
2421 printk(KERN_ERR
"Could not register tmpfs\n");
2425 shm_mnt
= vfs_kern_mount(&shmem_fs_type
, MS_NOUSER
,
2426 shmem_fs_type
.name
, NULL
);
2427 if (IS_ERR(shm_mnt
)) {
2428 error
= PTR_ERR(shm_mnt
);
2429 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2435 unregister_filesystem(&shmem_fs_type
);
2437 shmem_destroy_inodecache();
2439 bdi_destroy(&shmem_backing_dev_info
);
2441 shm_mnt
= ERR_PTR(error
);
2445 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
2447 * mem_cgroup_get_shmem_target - find page or swap assigned to the shmem file
2448 * @inode: the inode to be searched
2449 * @index: the page offset to be searched
2450 * @pagep: the pointer for the found page to be stored
2451 * @swapp: the pointer for the found swap entry to be stored
2453 * If a page is found, refcount of it is incremented. Callers should handle
2456 void mem_cgroup_get_shmem_target(struct inode
*inode
, pgoff_t index
,
2457 struct page
**pagep
, swp_entry_t
*swapp
)
2459 struct shmem_inode_info
*info
= SHMEM_I(inode
);
2460 struct page
*page
= NULL
;
2461 swp_entry_t swap
= {0};
2463 if ((index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
2466 spin_lock(&info
->lock
);
2468 swap
= shmem_get_swap(info
, index
);
2470 page
= find_get_page(&swapper_space
, swap
.val
);
2473 page
= find_get_page(inode
->i_mapping
, index
);
2474 spin_unlock(&info
->lock
);
2481 #else /* !CONFIG_SHMEM */
2484 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2486 * This is intended for small system where the benefits of the full
2487 * shmem code (swap-backed and resource-limited) are outweighed by
2488 * their complexity. On systems without swap this code should be
2489 * effectively equivalent, but much lighter weight.
2492 #include <linux/ramfs.h>
2494 static struct file_system_type shmem_fs_type
= {
2496 .mount
= ramfs_mount
,
2497 .kill_sb
= kill_litter_super
,
2500 int __init
shmem_init(void)
2502 BUG_ON(register_filesystem(&shmem_fs_type
) != 0);
2504 shm_mnt
= kern_mount(&shmem_fs_type
);
2505 BUG_ON(IS_ERR(shm_mnt
));
2510 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
2515 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
2520 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
2522 truncate_inode_pages_range(inode
->i_mapping
, lstart
, lend
);
2524 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
2526 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
2528 * mem_cgroup_get_shmem_target - find page or swap assigned to the shmem file
2529 * @inode: the inode to be searched
2530 * @index: the page offset to be searched
2531 * @pagep: the pointer for the found page to be stored
2532 * @swapp: the pointer for the found swap entry to be stored
2534 * If a page is found, refcount of it is incremented. Callers should handle
2537 void mem_cgroup_get_shmem_target(struct inode
*inode
, pgoff_t index
,
2538 struct page
**pagep
, swp_entry_t
*swapp
)
2540 struct page
*page
= NULL
;
2542 if ((index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
))
2544 page
= find_get_page(inode
->i_mapping
, index
);
2547 *swapp
= (swp_entry_t
){0};
2551 #define shmem_vm_ops generic_file_vm_ops
2552 #define shmem_file_operations ramfs_file_operations
2553 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2554 #define shmem_acct_size(flags, size) 0
2555 #define shmem_unacct_size(flags, size) do {} while (0)
2557 #endif /* CONFIG_SHMEM */
2562 * shmem_file_setup - get an unlinked file living in tmpfs
2563 * @name: name for dentry (to be seen in /proc/<pid>/maps
2564 * @size: size to be set for the file
2565 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2567 struct file
*shmem_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2571 struct inode
*inode
;
2573 struct dentry
*root
;
2576 if (IS_ERR(shm_mnt
))
2577 return (void *)shm_mnt
;
2579 if (size
< 0 || size
> MAX_LFS_FILESIZE
)
2580 return ERR_PTR(-EINVAL
);
2582 if (shmem_acct_size(flags
, size
))
2583 return ERR_PTR(-ENOMEM
);
2587 this.len
= strlen(name
);
2588 this.hash
= 0; /* will go */
2589 root
= shm_mnt
->mnt_root
;
2590 path
.dentry
= d_alloc(root
, &this);
2593 path
.mnt
= mntget(shm_mnt
);
2596 inode
= shmem_get_inode(root
->d_sb
, NULL
, S_IFREG
| S_IRWXUGO
, 0, flags
);
2600 d_instantiate(path
.dentry
, inode
);
2601 inode
->i_size
= size
;
2602 inode
->i_nlink
= 0; /* It is unlinked */
2604 error
= ramfs_nommu_expand_for_mapping(inode
, size
);
2610 file
= alloc_file(&path
, FMODE_WRITE
| FMODE_READ
,
2611 &shmem_file_operations
);
2620 shmem_unacct_size(flags
, size
);
2621 return ERR_PTR(error
);
2623 EXPORT_SYMBOL_GPL(shmem_file_setup
);
2626 * shmem_zero_setup - setup a shared anonymous mapping
2627 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2629 int shmem_zero_setup(struct vm_area_struct
*vma
)
2632 loff_t size
= vma
->vm_end
- vma
->vm_start
;
2634 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
2636 return PTR_ERR(file
);
2640 vma
->vm_file
= file
;
2641 vma
->vm_ops
= &shmem_vm_ops
;
2642 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
2647 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
2648 * @mapping: the page's address_space
2649 * @index: the page index
2650 * @gfp: the page allocator flags to use if allocating
2652 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
2653 * with any new page allocations done using the specified allocation flags.
2654 * But read_cache_page_gfp() uses the ->readpage() method: which does not
2655 * suit tmpfs, since it may have pages in swapcache, and needs to find those
2656 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
2658 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
2659 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
2661 struct page
*shmem_read_mapping_page_gfp(struct address_space
*mapping
,
2662 pgoff_t index
, gfp_t gfp
)
2665 struct inode
*inode
= mapping
->host
;
2669 BUG_ON(mapping
->a_ops
!= &shmem_aops
);
2670 error
= shmem_getpage_gfp(inode
, index
, &page
, SGP_CACHE
, gfp
, NULL
);
2672 page
= ERR_PTR(error
);
2678 * The tiny !SHMEM case uses ramfs without swap
2680 return read_cache_page_gfp(mapping
, index
, gfp
);
2683 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp
);