2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
21 * This file is released under the GPL.
25 #include <linux/init.h>
26 #include <linux/vfs.h>
27 #include <linux/mount.h>
28 #include <linux/pagemap.h>
29 #include <linux/file.h>
31 #include <linux/export.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/pagevec.h>
55 #include <linux/percpu_counter.h>
56 #include <linux/falloc.h>
57 #include <linux/splice.h>
58 #include <linux/security.h>
59 #include <linux/swapops.h>
60 #include <linux/mempolicy.h>
61 #include <linux/namei.h>
62 #include <linux/ctype.h>
63 #include <linux/migrate.h>
64 #include <linux/highmem.h>
65 #include <linux/seq_file.h>
66 #include <linux/magic.h>
68 #include <asm/uaccess.h>
69 #include <asm/pgtable.h>
71 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
72 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
74 /* Pretend that each entry is of this size in directory's i_size */
75 #define BOGO_DIRENT_SIZE 20
77 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
78 #define SHORT_SYMLINK_LEN 128
81 struct list_head list
; /* anchored by shmem_inode_info->xattr_list */
82 char *name
; /* xattr name */
88 * shmem_fallocate and shmem_writepage communicate via inode->i_private
89 * (with i_mutex making sure that it has only one user at a time):
90 * we would prefer not to enlarge the shmem inode just for that.
93 pgoff_t start
; /* start of range currently being fallocated */
94 pgoff_t next
; /* the next page offset to be fallocated */
95 pgoff_t nr_falloced
; /* how many new pages have been fallocated */
96 pgoff_t nr_unswapped
; /* how often writepage refused to swap out */
99 /* Flag allocation requirements to shmem_getpage */
101 SGP_READ
, /* don't exceed i_size, don't allocate page */
102 SGP_CACHE
, /* don't exceed i_size, may allocate page */
103 SGP_DIRTY
, /* like SGP_CACHE, but set new page dirty */
104 SGP_WRITE
, /* may exceed i_size, may allocate !Uptodate page */
105 SGP_FALLOC
, /* like SGP_WRITE, but make existing page Uptodate */
109 static unsigned long shmem_default_max_blocks(void)
111 return totalram_pages
/ 2;
114 static unsigned long shmem_default_max_inodes(void)
116 return min(totalram_pages
- totalhigh_pages
, totalram_pages
/ 2);
120 static bool shmem_should_replace_page(struct page
*page
, gfp_t gfp
);
121 static int shmem_replace_page(struct page
**pagep
, gfp_t gfp
,
122 struct shmem_inode_info
*info
, pgoff_t index
);
123 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
124 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
);
126 static inline int shmem_getpage(struct inode
*inode
, pgoff_t index
,
127 struct page
**pagep
, enum sgp_type sgp
, int *fault_type
)
129 return shmem_getpage_gfp(inode
, index
, pagep
, sgp
,
130 mapping_gfp_mask(inode
->i_mapping
), fault_type
);
133 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
135 return sb
->s_fs_info
;
139 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
140 * for shared memory and for shared anonymous (/dev/zero) mappings
141 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
142 * consistent with the pre-accounting of private mappings ...
144 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
146 return (flags
& VM_NORESERVE
) ?
147 0 : security_vm_enough_memory_mm(current
->mm
, VM_ACCT(size
));
150 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
152 if (!(flags
& VM_NORESERVE
))
153 vm_unacct_memory(VM_ACCT(size
));
157 * ... whereas tmpfs objects are accounted incrementally as
158 * pages are allocated, in order to allow huge sparse files.
159 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
160 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
162 static inline int shmem_acct_block(unsigned long flags
)
164 return (flags
& VM_NORESERVE
) ?
165 security_vm_enough_memory_mm(current
->mm
, VM_ACCT(PAGE_CACHE_SIZE
)) : 0;
168 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
170 if (flags
& VM_NORESERVE
)
171 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
174 static const struct super_operations shmem_ops
;
175 static const struct address_space_operations shmem_aops
;
176 static const struct file_operations shmem_file_operations
;
177 static const struct inode_operations shmem_inode_operations
;
178 static const struct inode_operations shmem_dir_inode_operations
;
179 static const struct inode_operations shmem_special_inode_operations
;
180 static const struct vm_operations_struct shmem_vm_ops
;
182 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
183 .ra_pages
= 0, /* No readahead */
184 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
| BDI_CAP_SWAP_BACKED
,
187 static LIST_HEAD(shmem_swaplist
);
188 static DEFINE_MUTEX(shmem_swaplist_mutex
);
190 static int shmem_reserve_inode(struct super_block
*sb
)
192 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
193 if (sbinfo
->max_inodes
) {
194 spin_lock(&sbinfo
->stat_lock
);
195 if (!sbinfo
->free_inodes
) {
196 spin_unlock(&sbinfo
->stat_lock
);
199 sbinfo
->free_inodes
--;
200 spin_unlock(&sbinfo
->stat_lock
);
205 static void shmem_free_inode(struct super_block
*sb
)
207 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
208 if (sbinfo
->max_inodes
) {
209 spin_lock(&sbinfo
->stat_lock
);
210 sbinfo
->free_inodes
++;
211 spin_unlock(&sbinfo
->stat_lock
);
216 * shmem_recalc_inode - recalculate the block usage of an inode
217 * @inode: inode to recalc
219 * We have to calculate the free blocks since the mm can drop
220 * undirtied hole pages behind our back.
222 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
223 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
225 * It has to be called with the spinlock held.
227 static void shmem_recalc_inode(struct inode
*inode
)
229 struct shmem_inode_info
*info
= SHMEM_I(inode
);
232 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
234 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
235 if (sbinfo
->max_blocks
)
236 percpu_counter_add(&sbinfo
->used_blocks
, -freed
);
237 info
->alloced
-= freed
;
238 inode
->i_blocks
-= freed
* BLOCKS_PER_PAGE
;
239 shmem_unacct_blocks(info
->flags
, freed
);
244 * Replace item expected in radix tree by a new item, while holding tree lock.
246 static int shmem_radix_tree_replace(struct address_space
*mapping
,
247 pgoff_t index
, void *expected
, void *replacement
)
252 VM_BUG_ON(!expected
);
253 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
, index
);
255 item
= radix_tree_deref_slot_protected(pslot
,
256 &mapping
->tree_lock
);
257 if (item
!= expected
)
260 radix_tree_replace_slot(pslot
, replacement
);
262 radix_tree_delete(&mapping
->page_tree
, index
);
267 * Like add_to_page_cache_locked, but error if expected item has gone.
269 static int shmem_add_to_page_cache(struct page
*page
,
270 struct address_space
*mapping
,
271 pgoff_t index
, gfp_t gfp
, void *expected
)
275 VM_BUG_ON(!PageLocked(page
));
276 VM_BUG_ON(!PageSwapBacked(page
));
279 error
= radix_tree_preload(gfp
& GFP_RECLAIM_MASK
);
281 page_cache_get(page
);
282 page
->mapping
= mapping
;
285 spin_lock_irq(&mapping
->tree_lock
);
287 error
= radix_tree_insert(&mapping
->page_tree
,
290 error
= shmem_radix_tree_replace(mapping
, index
,
294 __inc_zone_page_state(page
, NR_FILE_PAGES
);
295 __inc_zone_page_state(page
, NR_SHMEM
);
296 spin_unlock_irq(&mapping
->tree_lock
);
298 page
->mapping
= NULL
;
299 spin_unlock_irq(&mapping
->tree_lock
);
300 page_cache_release(page
);
303 radix_tree_preload_end();
306 mem_cgroup_uncharge_cache_page(page
);
311 * Like delete_from_page_cache, but substitutes swap for page.
313 static void shmem_delete_from_page_cache(struct page
*page
, void *radswap
)
315 struct address_space
*mapping
= page
->mapping
;
318 spin_lock_irq(&mapping
->tree_lock
);
319 error
= shmem_radix_tree_replace(mapping
, page
->index
, page
, radswap
);
320 page
->mapping
= NULL
;
322 __dec_zone_page_state(page
, NR_FILE_PAGES
);
323 __dec_zone_page_state(page
, NR_SHMEM
);
324 spin_unlock_irq(&mapping
->tree_lock
);
325 page_cache_release(page
);
330 * Like find_get_pages, but collecting swap entries as well as pages.
332 static unsigned shmem_find_get_pages_and_swap(struct address_space
*mapping
,
333 pgoff_t start
, unsigned int nr_pages
,
334 struct page
**pages
, pgoff_t
*indices
)
338 unsigned int nr_found
;
342 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
343 (void ***)pages
, indices
, start
, nr_pages
);
345 for (i
= 0; i
< nr_found
; i
++) {
348 page
= radix_tree_deref_slot((void **)pages
[i
]);
351 if (radix_tree_exception(page
)) {
352 if (radix_tree_deref_retry(page
))
355 * Otherwise, we must be storing a swap entry
356 * here as an exceptional entry: so return it
357 * without attempting to raise page count.
361 if (!page_cache_get_speculative(page
))
364 /* Has the page moved? */
365 if (unlikely(page
!= *((void **)pages
[i
]))) {
366 page_cache_release(page
);
370 indices
[ret
] = indices
[i
];
374 if (unlikely(!ret
&& nr_found
))
381 * Remove swap entry from radix tree, free the swap and its page cache.
383 static int shmem_free_swap(struct address_space
*mapping
,
384 pgoff_t index
, void *radswap
)
388 spin_lock_irq(&mapping
->tree_lock
);
389 error
= shmem_radix_tree_replace(mapping
, index
, radswap
, NULL
);
390 spin_unlock_irq(&mapping
->tree_lock
);
392 free_swap_and_cache(radix_to_swp_entry(radswap
));
397 * Pagevec may contain swap entries, so shuffle up pages before releasing.
399 static void shmem_deswap_pagevec(struct pagevec
*pvec
)
403 for (i
= 0, j
= 0; i
< pagevec_count(pvec
); i
++) {
404 struct page
*page
= pvec
->pages
[i
];
405 if (!radix_tree_exceptional_entry(page
))
406 pvec
->pages
[j
++] = page
;
412 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
414 void shmem_unlock_mapping(struct address_space
*mapping
)
417 pgoff_t indices
[PAGEVEC_SIZE
];
420 pagevec_init(&pvec
, 0);
422 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
424 while (!mapping_unevictable(mapping
)) {
426 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
427 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
429 pvec
.nr
= shmem_find_get_pages_and_swap(mapping
, index
,
430 PAGEVEC_SIZE
, pvec
.pages
, indices
);
433 index
= indices
[pvec
.nr
- 1] + 1;
434 shmem_deswap_pagevec(&pvec
);
435 check_move_unevictable_pages(pvec
.pages
, pvec
.nr
);
436 pagevec_release(&pvec
);
442 * Remove range of pages and swap entries from radix tree, and free them.
443 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
445 static void shmem_undo_range(struct inode
*inode
, loff_t lstart
, loff_t lend
,
448 struct address_space
*mapping
= inode
->i_mapping
;
449 struct shmem_inode_info
*info
= SHMEM_I(inode
);
450 pgoff_t start
= (lstart
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
451 pgoff_t end
= (lend
+ 1) >> PAGE_CACHE_SHIFT
;
452 unsigned int partial_start
= lstart
& (PAGE_CACHE_SIZE
- 1);
453 unsigned int partial_end
= (lend
+ 1) & (PAGE_CACHE_SIZE
- 1);
455 pgoff_t indices
[PAGEVEC_SIZE
];
456 long nr_swaps_freed
= 0;
461 end
= -1; /* unsigned, so actually very big */
463 pagevec_init(&pvec
, 0);
465 while (index
< end
) {
466 pvec
.nr
= shmem_find_get_pages_and_swap(mapping
, index
,
467 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
),
468 pvec
.pages
, indices
);
471 mem_cgroup_uncharge_start();
472 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
473 struct page
*page
= pvec
.pages
[i
];
479 if (radix_tree_exceptional_entry(page
)) {
482 nr_swaps_freed
+= !shmem_free_swap(mapping
,
487 if (!trylock_page(page
))
489 if (!unfalloc
|| !PageUptodate(page
)) {
490 if (page
->mapping
== mapping
) {
491 VM_BUG_ON(PageWriteback(page
));
492 truncate_inode_page(mapping
, page
);
497 shmem_deswap_pagevec(&pvec
);
498 pagevec_release(&pvec
);
499 mem_cgroup_uncharge_end();
505 struct page
*page
= NULL
;
506 shmem_getpage(inode
, start
- 1, &page
, SGP_READ
, NULL
);
508 unsigned int top
= PAGE_CACHE_SIZE
;
513 zero_user_segment(page
, partial_start
, top
);
514 set_page_dirty(page
);
516 page_cache_release(page
);
520 struct page
*page
= NULL
;
521 shmem_getpage(inode
, end
, &page
, SGP_READ
, NULL
);
523 zero_user_segment(page
, 0, partial_end
);
524 set_page_dirty(page
);
526 page_cache_release(page
);
535 pvec
.nr
= shmem_find_get_pages_and_swap(mapping
, index
,
536 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
),
537 pvec
.pages
, indices
);
539 if (index
== start
|| unfalloc
)
544 if ((index
== start
|| unfalloc
) && indices
[0] >= end
) {
545 shmem_deswap_pagevec(&pvec
);
546 pagevec_release(&pvec
);
549 mem_cgroup_uncharge_start();
550 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
551 struct page
*page
= pvec
.pages
[i
];
557 if (radix_tree_exceptional_entry(page
)) {
560 nr_swaps_freed
+= !shmem_free_swap(mapping
,
566 if (!unfalloc
|| !PageUptodate(page
)) {
567 if (page
->mapping
== mapping
) {
568 VM_BUG_ON(PageWriteback(page
));
569 truncate_inode_page(mapping
, page
);
574 shmem_deswap_pagevec(&pvec
);
575 pagevec_release(&pvec
);
576 mem_cgroup_uncharge_end();
580 spin_lock(&info
->lock
);
581 info
->swapped
-= nr_swaps_freed
;
582 shmem_recalc_inode(inode
);
583 spin_unlock(&info
->lock
);
586 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
588 shmem_undo_range(inode
, lstart
, lend
, false);
589 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
591 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
593 static int shmem_setattr(struct dentry
*dentry
, struct iattr
*attr
)
595 struct inode
*inode
= dentry
->d_inode
;
598 error
= inode_change_ok(inode
, attr
);
602 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
603 loff_t oldsize
= inode
->i_size
;
604 loff_t newsize
= attr
->ia_size
;
606 if (newsize
!= oldsize
) {
607 i_size_write(inode
, newsize
);
608 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
610 if (newsize
< oldsize
) {
611 loff_t holebegin
= round_up(newsize
, PAGE_SIZE
);
612 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
613 shmem_truncate_range(inode
, newsize
, (loff_t
)-1);
614 /* unmap again to remove racily COWed private pages */
615 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
619 setattr_copy(inode
, attr
);
620 #ifdef CONFIG_TMPFS_POSIX_ACL
621 if (attr
->ia_valid
& ATTR_MODE
)
622 error
= generic_acl_chmod(inode
);
627 static void shmem_evict_inode(struct inode
*inode
)
629 struct shmem_inode_info
*info
= SHMEM_I(inode
);
630 struct shmem_xattr
*xattr
, *nxattr
;
632 if (inode
->i_mapping
->a_ops
== &shmem_aops
) {
633 shmem_unacct_size(info
->flags
, inode
->i_size
);
635 shmem_truncate_range(inode
, 0, (loff_t
)-1);
636 if (!list_empty(&info
->swaplist
)) {
637 mutex_lock(&shmem_swaplist_mutex
);
638 list_del_init(&info
->swaplist
);
639 mutex_unlock(&shmem_swaplist_mutex
);
642 kfree(info
->symlink
);
644 list_for_each_entry_safe(xattr
, nxattr
, &info
->xattr_list
, list
) {
648 BUG_ON(inode
->i_blocks
);
649 shmem_free_inode(inode
->i_sb
);
654 * If swap found in inode, free it and move page from swapcache to filecache.
656 static int shmem_unuse_inode(struct shmem_inode_info
*info
,
657 swp_entry_t swap
, struct page
**pagep
)
659 struct address_space
*mapping
= info
->vfs_inode
.i_mapping
;
665 radswap
= swp_to_radix_entry(swap
);
666 index
= radix_tree_locate_item(&mapping
->page_tree
, radswap
);
671 * Move _head_ to start search for next from here.
672 * But be careful: shmem_evict_inode checks list_empty without taking
673 * mutex, and there's an instant in list_move_tail when info->swaplist
674 * would appear empty, if it were the only one on shmem_swaplist.
676 if (shmem_swaplist
.next
!= &info
->swaplist
)
677 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
679 gfp
= mapping_gfp_mask(mapping
);
680 if (shmem_should_replace_page(*pagep
, gfp
)) {
681 mutex_unlock(&shmem_swaplist_mutex
);
682 error
= shmem_replace_page(pagep
, gfp
, info
, index
);
683 mutex_lock(&shmem_swaplist_mutex
);
685 * We needed to drop mutex to make that restrictive page
686 * allocation; but the inode might already be freed by now,
687 * and we cannot refer to inode or mapping or info to check.
688 * However, we do hold page lock on the PageSwapCache page,
689 * so can check if that still has our reference remaining.
691 if (!page_swapcount(*pagep
))
696 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
697 * but also to hold up shmem_evict_inode(): so inode cannot be freed
698 * beneath us (pagelock doesn't help until the page is in pagecache).
701 error
= shmem_add_to_page_cache(*pagep
, mapping
, index
,
702 GFP_NOWAIT
, radswap
);
703 if (error
!= -ENOMEM
) {
705 * Truncation and eviction use free_swap_and_cache(), which
706 * only does trylock page: if we raced, best clean up here.
708 delete_from_swap_cache(*pagep
);
709 set_page_dirty(*pagep
);
711 spin_lock(&info
->lock
);
713 spin_unlock(&info
->lock
);
716 error
= 1; /* not an error, but entry was found */
722 * Search through swapped inodes to find and replace swap by page.
724 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
726 struct list_head
*this, *next
;
727 struct shmem_inode_info
*info
;
732 * There's a faint possibility that swap page was replaced before
733 * caller locked it: it will come back later with the right page.
735 if (unlikely(!PageSwapCache(page
)))
739 * Charge page using GFP_KERNEL while we can wait, before taking
740 * the shmem_swaplist_mutex which might hold up shmem_writepage().
741 * Charged back to the user (not to caller) when swap account is used.
743 error
= mem_cgroup_cache_charge(page
, current
->mm
, GFP_KERNEL
);
746 /* No radix_tree_preload: swap entry keeps a place for page in tree */
748 mutex_lock(&shmem_swaplist_mutex
);
749 list_for_each_safe(this, next
, &shmem_swaplist
) {
750 info
= list_entry(this, struct shmem_inode_info
, swaplist
);
752 found
= shmem_unuse_inode(info
, swap
, &page
);
754 list_del_init(&info
->swaplist
);
759 mutex_unlock(&shmem_swaplist_mutex
);
765 page_cache_release(page
);
770 * Move the page from the page cache to the swap cache.
772 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
774 struct shmem_inode_info
*info
;
775 struct address_space
*mapping
;
780 BUG_ON(!PageLocked(page
));
781 mapping
= page
->mapping
;
783 inode
= mapping
->host
;
784 info
= SHMEM_I(inode
);
785 if (info
->flags
& VM_LOCKED
)
787 if (!total_swap_pages
)
791 * shmem_backing_dev_info's capabilities prevent regular writeback or
792 * sync from ever calling shmem_writepage; but a stacking filesystem
793 * might use ->writepage of its underlying filesystem, in which case
794 * tmpfs should write out to swap only in response to memory pressure,
795 * and not for the writeback threads or sync.
797 if (!wbc
->for_reclaim
) {
798 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
803 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
804 * value into swapfile.c, the only way we can correctly account for a
805 * fallocated page arriving here is now to initialize it and write it.
807 * That's okay for a page already fallocated earlier, but if we have
808 * not yet completed the fallocation, then (a) we want to keep track
809 * of this page in case we have to undo it, and (b) it may not be a
810 * good idea to continue anyway, once we're pushing into swap. So
811 * reactivate the page, and let shmem_fallocate() quit when too many.
813 if (!PageUptodate(page
)) {
814 if (inode
->i_private
) {
815 struct shmem_falloc
*shmem_falloc
;
816 spin_lock(&inode
->i_lock
);
817 shmem_falloc
= inode
->i_private
;
819 index
>= shmem_falloc
->start
&&
820 index
< shmem_falloc
->next
)
821 shmem_falloc
->nr_unswapped
++;
824 spin_unlock(&inode
->i_lock
);
828 clear_highpage(page
);
829 flush_dcache_page(page
);
830 SetPageUptodate(page
);
833 swap
= get_swap_page();
838 * Add inode to shmem_unuse()'s list of swapped-out inodes,
839 * if it's not already there. Do it now before the page is
840 * moved to swap cache, when its pagelock no longer protects
841 * the inode from eviction. But don't unlock the mutex until
842 * we've incremented swapped, because shmem_unuse_inode() will
843 * prune a !swapped inode from the swaplist under this mutex.
845 mutex_lock(&shmem_swaplist_mutex
);
846 if (list_empty(&info
->swaplist
))
847 list_add_tail(&info
->swaplist
, &shmem_swaplist
);
849 if (add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
850 swap_shmem_alloc(swap
);
851 shmem_delete_from_page_cache(page
, swp_to_radix_entry(swap
));
853 spin_lock(&info
->lock
);
855 shmem_recalc_inode(inode
);
856 spin_unlock(&info
->lock
);
858 mutex_unlock(&shmem_swaplist_mutex
);
859 BUG_ON(page_mapped(page
));
860 swap_writepage(page
, wbc
);
864 mutex_unlock(&shmem_swaplist_mutex
);
865 swapcache_free(swap
, NULL
);
867 set_page_dirty(page
);
868 if (wbc
->for_reclaim
)
869 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
876 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
880 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
881 return; /* show nothing */
883 mpol_to_str(buffer
, sizeof(buffer
), mpol
, 1);
885 seq_printf(seq
, ",mpol=%s", buffer
);
888 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
890 struct mempolicy
*mpol
= NULL
;
892 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
895 spin_unlock(&sbinfo
->stat_lock
);
899 #endif /* CONFIG_TMPFS */
901 static struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
902 struct shmem_inode_info
*info
, pgoff_t index
)
904 struct mempolicy mpol
, *spol
;
905 struct vm_area_struct pvma
;
907 spol
= mpol_cond_copy(&mpol
,
908 mpol_shared_policy_lookup(&info
->policy
, index
));
910 /* Create a pseudo vma that just contains the policy */
912 pvma
.vm_pgoff
= index
;
914 pvma
.vm_policy
= spol
;
915 return swapin_readahead(swap
, gfp
, &pvma
, 0);
918 static struct page
*shmem_alloc_page(gfp_t gfp
,
919 struct shmem_inode_info
*info
, pgoff_t index
)
921 struct vm_area_struct pvma
;
923 /* Create a pseudo vma that just contains the policy */
925 pvma
.vm_pgoff
= index
;
927 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, index
);
930 * alloc_page_vma() will drop the shared policy reference
932 return alloc_page_vma(gfp
, &pvma
, 0);
934 #else /* !CONFIG_NUMA */
936 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
939 #endif /* CONFIG_TMPFS */
941 static inline struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
942 struct shmem_inode_info
*info
, pgoff_t index
)
944 return swapin_readahead(swap
, gfp
, NULL
, 0);
947 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
948 struct shmem_inode_info
*info
, pgoff_t index
)
950 return alloc_page(gfp
);
952 #endif /* CONFIG_NUMA */
954 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
955 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
962 * When a page is moved from swapcache to shmem filecache (either by the
963 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
964 * shmem_unuse_inode()), it may have been read in earlier from swap, in
965 * ignorance of the mapping it belongs to. If that mapping has special
966 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
967 * we may need to copy to a suitable page before moving to filecache.
969 * In a future release, this may well be extended to respect cpuset and
970 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
971 * but for now it is a simple matter of zone.
973 static bool shmem_should_replace_page(struct page
*page
, gfp_t gfp
)
975 return page_zonenum(page
) > gfp_zone(gfp
);
978 static int shmem_replace_page(struct page
**pagep
, gfp_t gfp
,
979 struct shmem_inode_info
*info
, pgoff_t index
)
981 struct page
*oldpage
, *newpage
;
982 struct address_space
*swap_mapping
;
987 swap_index
= page_private(oldpage
);
988 swap_mapping
= page_mapping(oldpage
);
991 * We have arrived here because our zones are constrained, so don't
992 * limit chance of success by further cpuset and node constraints.
994 gfp
&= ~GFP_CONSTRAINT_MASK
;
995 newpage
= shmem_alloc_page(gfp
, info
, index
);
998 VM_BUG_ON(shmem_should_replace_page(newpage
, gfp
));
1001 page_cache_get(newpage
);
1002 copy_highpage(newpage
, oldpage
);
1004 VM_BUG_ON(!PageLocked(oldpage
));
1005 __set_page_locked(newpage
);
1006 VM_BUG_ON(!PageUptodate(oldpage
));
1007 SetPageUptodate(newpage
);
1008 VM_BUG_ON(!PageSwapBacked(oldpage
));
1009 SetPageSwapBacked(newpage
);
1010 VM_BUG_ON(!swap_index
);
1011 set_page_private(newpage
, swap_index
);
1012 VM_BUG_ON(!PageSwapCache(oldpage
));
1013 SetPageSwapCache(newpage
);
1016 * Our caller will very soon move newpage out of swapcache, but it's
1017 * a nice clean interface for us to replace oldpage by newpage there.
1019 spin_lock_irq(&swap_mapping
->tree_lock
);
1020 error
= shmem_radix_tree_replace(swap_mapping
, swap_index
, oldpage
,
1022 __inc_zone_page_state(newpage
, NR_FILE_PAGES
);
1023 __dec_zone_page_state(oldpage
, NR_FILE_PAGES
);
1024 spin_unlock_irq(&swap_mapping
->tree_lock
);
1027 mem_cgroup_replace_page_cache(oldpage
, newpage
);
1028 lru_cache_add_anon(newpage
);
1030 ClearPageSwapCache(oldpage
);
1031 set_page_private(oldpage
, 0);
1033 unlock_page(oldpage
);
1034 page_cache_release(oldpage
);
1035 page_cache_release(oldpage
);
1040 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1042 * If we allocate a new one we do not mark it dirty. That's up to the
1043 * vm. If we swap it in we mark it dirty since we also free the swap
1044 * entry since a page cannot live in both the swap and page cache
1046 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
1047 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
)
1049 struct address_space
*mapping
= inode
->i_mapping
;
1050 struct shmem_inode_info
*info
;
1051 struct shmem_sb_info
*sbinfo
;
1058 if (index
> (MAX_LFS_FILESIZE
>> PAGE_CACHE_SHIFT
))
1062 page
= find_lock_page(mapping
, index
);
1063 if (radix_tree_exceptional_entry(page
)) {
1064 swap
= radix_to_swp_entry(page
);
1068 if (sgp
!= SGP_WRITE
&& sgp
!= SGP_FALLOC
&&
1069 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1074 /* fallocated page? */
1075 if (page
&& !PageUptodate(page
)) {
1076 if (sgp
!= SGP_READ
)
1079 page_cache_release(page
);
1082 if (page
|| (sgp
== SGP_READ
&& !swap
.val
)) {
1088 * Fast cache lookup did not find it:
1089 * bring it back from swap or allocate.
1091 info
= SHMEM_I(inode
);
1092 sbinfo
= SHMEM_SB(inode
->i_sb
);
1095 /* Look it up and read it in.. */
1096 page
= lookup_swap_cache(swap
);
1098 /* here we actually do the io */
1100 *fault_type
|= VM_FAULT_MAJOR
;
1101 page
= shmem_swapin(swap
, gfp
, info
, index
);
1108 /* We have to do this with page locked to prevent races */
1110 if (!PageSwapCache(page
) || page
->mapping
) {
1111 error
= -EEXIST
; /* try again */
1114 if (!PageUptodate(page
)) {
1118 wait_on_page_writeback(page
);
1120 if (shmem_should_replace_page(page
, gfp
)) {
1121 error
= shmem_replace_page(&page
, gfp
, info
, index
);
1126 error
= mem_cgroup_cache_charge(page
, current
->mm
,
1127 gfp
& GFP_RECLAIM_MASK
);
1129 error
= shmem_add_to_page_cache(page
, mapping
, index
,
1130 gfp
, swp_to_radix_entry(swap
));
1134 spin_lock(&info
->lock
);
1136 shmem_recalc_inode(inode
);
1137 spin_unlock(&info
->lock
);
1139 delete_from_swap_cache(page
);
1140 set_page_dirty(page
);
1144 if (shmem_acct_block(info
->flags
)) {
1148 if (sbinfo
->max_blocks
) {
1149 if (percpu_counter_compare(&sbinfo
->used_blocks
,
1150 sbinfo
->max_blocks
) >= 0) {
1154 percpu_counter_inc(&sbinfo
->used_blocks
);
1157 page
= shmem_alloc_page(gfp
, info
, index
);
1163 SetPageSwapBacked(page
);
1164 __set_page_locked(page
);
1165 error
= mem_cgroup_cache_charge(page
, current
->mm
,
1166 gfp
& GFP_RECLAIM_MASK
);
1168 error
= shmem_add_to_page_cache(page
, mapping
, index
,
1172 lru_cache_add_anon(page
);
1174 spin_lock(&info
->lock
);
1176 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1177 shmem_recalc_inode(inode
);
1178 spin_unlock(&info
->lock
);
1182 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1184 if (sgp
== SGP_FALLOC
)
1188 * Let SGP_WRITE caller clear ends if write does not fill page;
1189 * but SGP_FALLOC on a page fallocated earlier must initialize
1190 * it now, lest undo on failure cancel our earlier guarantee.
1192 if (sgp
!= SGP_WRITE
) {
1193 clear_highpage(page
);
1194 flush_dcache_page(page
);
1195 SetPageUptodate(page
);
1197 if (sgp
== SGP_DIRTY
)
1198 set_page_dirty(page
);
1201 /* Perhaps the file has been truncated since we checked */
1202 if (sgp
!= SGP_WRITE
&& sgp
!= SGP_FALLOC
&&
1203 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1217 info
= SHMEM_I(inode
);
1218 ClearPageDirty(page
);
1219 delete_from_page_cache(page
);
1220 spin_lock(&info
->lock
);
1222 inode
->i_blocks
-= BLOCKS_PER_PAGE
;
1223 spin_unlock(&info
->lock
);
1225 sbinfo
= SHMEM_SB(inode
->i_sb
);
1226 if (sbinfo
->max_blocks
)
1227 percpu_counter_add(&sbinfo
->used_blocks
, -1);
1229 shmem_unacct_blocks(info
->flags
, 1);
1231 if (swap
.val
&& error
!= -EINVAL
) {
1232 struct page
*test
= find_get_page(mapping
, index
);
1233 if (test
&& !radix_tree_exceptional_entry(test
))
1234 page_cache_release(test
);
1235 /* Have another try if the entry has changed */
1236 if (test
!= swp_to_radix_entry(swap
))
1241 page_cache_release(page
);
1243 if (error
== -ENOSPC
&& !once
++) {
1244 info
= SHMEM_I(inode
);
1245 spin_lock(&info
->lock
);
1246 shmem_recalc_inode(inode
);
1247 spin_unlock(&info
->lock
);
1250 if (error
== -EEXIST
)
1255 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1257 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1259 int ret
= VM_FAULT_LOCKED
;
1261 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1263 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1265 if (ret
& VM_FAULT_MAJOR
) {
1266 count_vm_event(PGMAJFAULT
);
1267 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1273 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*mpol
)
1275 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1276 return mpol_set_shared_policy(&SHMEM_I(inode
)->policy
, vma
, mpol
);
1279 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1282 struct inode
*inode
= vma
->vm_file
->f_path
.dentry
->d_inode
;
1285 index
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1286 return mpol_shared_policy_lookup(&SHMEM_I(inode
)->policy
, index
);
1290 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1292 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1293 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1294 int retval
= -ENOMEM
;
1296 spin_lock(&info
->lock
);
1297 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1298 if (!user_shm_lock(inode
->i_size
, user
))
1300 info
->flags
|= VM_LOCKED
;
1301 mapping_set_unevictable(file
->f_mapping
);
1303 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1304 user_shm_unlock(inode
->i_size
, user
);
1305 info
->flags
&= ~VM_LOCKED
;
1306 mapping_clear_unevictable(file
->f_mapping
);
1311 spin_unlock(&info
->lock
);
1315 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1317 file_accessed(file
);
1318 vma
->vm_ops
= &shmem_vm_ops
;
1319 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1323 static struct inode
*shmem_get_inode(struct super_block
*sb
, const struct inode
*dir
,
1324 umode_t mode
, dev_t dev
, unsigned long flags
)
1326 struct inode
*inode
;
1327 struct shmem_inode_info
*info
;
1328 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1330 if (shmem_reserve_inode(sb
))
1333 inode
= new_inode(sb
);
1335 inode
->i_ino
= get_next_ino();
1336 inode_init_owner(inode
, dir
, mode
);
1337 inode
->i_blocks
= 0;
1338 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1339 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1340 inode
->i_generation
= get_seconds();
1341 info
= SHMEM_I(inode
);
1342 memset(info
, 0, (char *)inode
- (char *)info
);
1343 spin_lock_init(&info
->lock
);
1344 info
->flags
= flags
& VM_NORESERVE
;
1345 INIT_LIST_HEAD(&info
->swaplist
);
1346 INIT_LIST_HEAD(&info
->xattr_list
);
1347 cache_no_acl(inode
);
1349 switch (mode
& S_IFMT
) {
1351 inode
->i_op
= &shmem_special_inode_operations
;
1352 init_special_inode(inode
, mode
, dev
);
1355 inode
->i_mapping
->a_ops
= &shmem_aops
;
1356 inode
->i_op
= &shmem_inode_operations
;
1357 inode
->i_fop
= &shmem_file_operations
;
1358 mpol_shared_policy_init(&info
->policy
,
1359 shmem_get_sbmpol(sbinfo
));
1363 /* Some things misbehave if size == 0 on a directory */
1364 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1365 inode
->i_op
= &shmem_dir_inode_operations
;
1366 inode
->i_fop
= &simple_dir_operations
;
1370 * Must not load anything in the rbtree,
1371 * mpol_free_shared_policy will not be called.
1373 mpol_shared_policy_init(&info
->policy
, NULL
);
1377 shmem_free_inode(sb
);
1382 static const struct inode_operations shmem_symlink_inode_operations
;
1383 static const struct inode_operations shmem_short_symlink_operations
;
1385 #ifdef CONFIG_TMPFS_XATTR
1386 static int shmem_initxattrs(struct inode
*, const struct xattr
*, void *);
1388 #define shmem_initxattrs NULL
1392 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1393 loff_t pos
, unsigned len
, unsigned flags
,
1394 struct page
**pagep
, void **fsdata
)
1396 struct inode
*inode
= mapping
->host
;
1397 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1398 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1402 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1403 loff_t pos
, unsigned len
, unsigned copied
,
1404 struct page
*page
, void *fsdata
)
1406 struct inode
*inode
= mapping
->host
;
1408 if (pos
+ copied
> inode
->i_size
)
1409 i_size_write(inode
, pos
+ copied
);
1411 if (!PageUptodate(page
)) {
1412 if (copied
< PAGE_CACHE_SIZE
) {
1413 unsigned from
= pos
& (PAGE_CACHE_SIZE
- 1);
1414 zero_user_segments(page
, 0, from
,
1415 from
+ copied
, PAGE_CACHE_SIZE
);
1417 SetPageUptodate(page
);
1419 set_page_dirty(page
);
1421 page_cache_release(page
);
1426 static void do_shmem_file_read(struct file
*filp
, loff_t
*ppos
, read_descriptor_t
*desc
, read_actor_t actor
)
1428 struct inode
*inode
= filp
->f_path
.dentry
->d_inode
;
1429 struct address_space
*mapping
= inode
->i_mapping
;
1431 unsigned long offset
;
1432 enum sgp_type sgp
= SGP_READ
;
1435 * Might this read be for a stacking filesystem? Then when reading
1436 * holes of a sparse file, we actually need to allocate those pages,
1437 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1439 if (segment_eq(get_fs(), KERNEL_DS
))
1442 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1443 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1446 struct page
*page
= NULL
;
1448 unsigned long nr
, ret
;
1449 loff_t i_size
= i_size_read(inode
);
1451 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1452 if (index
> end_index
)
1454 if (index
== end_index
) {
1455 nr
= i_size
& ~PAGE_CACHE_MASK
;
1460 desc
->error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1462 if (desc
->error
== -EINVAL
)
1470 * We must evaluate after, since reads (unlike writes)
1471 * are called without i_mutex protection against truncate
1473 nr
= PAGE_CACHE_SIZE
;
1474 i_size
= i_size_read(inode
);
1475 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1476 if (index
== end_index
) {
1477 nr
= i_size
& ~PAGE_CACHE_MASK
;
1480 page_cache_release(page
);
1488 * If users can be writing to this page using arbitrary
1489 * virtual addresses, take care about potential aliasing
1490 * before reading the page on the kernel side.
1492 if (mapping_writably_mapped(mapping
))
1493 flush_dcache_page(page
);
1495 * Mark the page accessed if we read the beginning.
1498 mark_page_accessed(page
);
1500 page
= ZERO_PAGE(0);
1501 page_cache_get(page
);
1505 * Ok, we have the page, and it's up-to-date, so
1506 * now we can copy it to user space...
1508 * The actor routine returns how many bytes were actually used..
1509 * NOTE! This may not be the same as how much of a user buffer
1510 * we filled up (we may be padding etc), so we can only update
1511 * "pos" here (the actor routine has to update the user buffer
1512 * pointers and the remaining count).
1514 ret
= actor(desc
, page
, offset
, nr
);
1516 index
+= offset
>> PAGE_CACHE_SHIFT
;
1517 offset
&= ~PAGE_CACHE_MASK
;
1519 page_cache_release(page
);
1520 if (ret
!= nr
|| !desc
->count
)
1526 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1527 file_accessed(filp
);
1530 static ssize_t
shmem_file_aio_read(struct kiocb
*iocb
,
1531 const struct iovec
*iov
, unsigned long nr_segs
, loff_t pos
)
1533 struct file
*filp
= iocb
->ki_filp
;
1537 loff_t
*ppos
= &iocb
->ki_pos
;
1539 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1543 for (seg
= 0; seg
< nr_segs
; seg
++) {
1544 read_descriptor_t desc
;
1547 desc
.arg
.buf
= iov
[seg
].iov_base
;
1548 desc
.count
= iov
[seg
].iov_len
;
1549 if (desc
.count
== 0)
1552 do_shmem_file_read(filp
, ppos
, &desc
, file_read_actor
);
1553 retval
+= desc
.written
;
1555 retval
= retval
?: desc
.error
;
1564 static ssize_t
shmem_file_splice_read(struct file
*in
, loff_t
*ppos
,
1565 struct pipe_inode_info
*pipe
, size_t len
,
1568 struct address_space
*mapping
= in
->f_mapping
;
1569 struct inode
*inode
= mapping
->host
;
1570 unsigned int loff
, nr_pages
, req_pages
;
1571 struct page
*pages
[PIPE_DEF_BUFFERS
];
1572 struct partial_page partial
[PIPE_DEF_BUFFERS
];
1574 pgoff_t index
, end_index
;
1577 struct splice_pipe_desc spd
= {
1581 .ops
= &page_cache_pipe_buf_ops
,
1582 .spd_release
= spd_release_page
,
1585 isize
= i_size_read(inode
);
1586 if (unlikely(*ppos
>= isize
))
1589 left
= isize
- *ppos
;
1590 if (unlikely(left
< len
))
1593 if (splice_grow_spd(pipe
, &spd
))
1596 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1597 loff
= *ppos
& ~PAGE_CACHE_MASK
;
1598 req_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1599 nr_pages
= min(req_pages
, pipe
->buffers
);
1601 spd
.nr_pages
= find_get_pages_contig(mapping
, index
,
1602 nr_pages
, spd
.pages
);
1603 index
+= spd
.nr_pages
;
1606 while (spd
.nr_pages
< nr_pages
) {
1607 error
= shmem_getpage(inode
, index
, &page
, SGP_CACHE
, NULL
);
1611 spd
.pages
[spd
.nr_pages
++] = page
;
1615 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1616 nr_pages
= spd
.nr_pages
;
1619 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
1620 unsigned int this_len
;
1625 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
1626 page
= spd
.pages
[page_nr
];
1628 if (!PageUptodate(page
) || page
->mapping
!= mapping
) {
1629 error
= shmem_getpage(inode
, index
, &page
,
1634 page_cache_release(spd
.pages
[page_nr
]);
1635 spd
.pages
[page_nr
] = page
;
1638 isize
= i_size_read(inode
);
1639 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1640 if (unlikely(!isize
|| index
> end_index
))
1643 if (end_index
== index
) {
1646 plen
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1650 this_len
= min(this_len
, plen
- loff
);
1654 spd
.partial
[page_nr
].offset
= loff
;
1655 spd
.partial
[page_nr
].len
= this_len
;
1662 while (page_nr
< nr_pages
)
1663 page_cache_release(spd
.pages
[page_nr
++]);
1666 error
= splice_to_pipe(pipe
, &spd
);
1668 splice_shrink_spd(pipe
, &spd
);
1677 static long shmem_fallocate(struct file
*file
, int mode
, loff_t offset
,
1680 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
1681 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
1682 struct shmem_falloc shmem_falloc
;
1683 pgoff_t start
, index
, end
;
1686 mutex_lock(&inode
->i_mutex
);
1688 if (mode
& FALLOC_FL_PUNCH_HOLE
) {
1689 struct address_space
*mapping
= file
->f_mapping
;
1690 loff_t unmap_start
= round_up(offset
, PAGE_SIZE
);
1691 loff_t unmap_end
= round_down(offset
+ len
, PAGE_SIZE
) - 1;
1693 if ((u64
)unmap_end
> (u64
)unmap_start
)
1694 unmap_mapping_range(mapping
, unmap_start
,
1695 1 + unmap_end
- unmap_start
, 0);
1696 shmem_truncate_range(inode
, offset
, offset
+ len
- 1);
1697 /* No need to unmap again: hole-punching leaves COWed pages */
1702 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1703 error
= inode_newsize_ok(inode
, offset
+ len
);
1707 start
= offset
>> PAGE_CACHE_SHIFT
;
1708 end
= (offset
+ len
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1709 /* Try to avoid a swapstorm if len is impossible to satisfy */
1710 if (sbinfo
->max_blocks
&& end
- start
> sbinfo
->max_blocks
) {
1715 shmem_falloc
.start
= start
;
1716 shmem_falloc
.next
= start
;
1717 shmem_falloc
.nr_falloced
= 0;
1718 shmem_falloc
.nr_unswapped
= 0;
1719 spin_lock(&inode
->i_lock
);
1720 inode
->i_private
= &shmem_falloc
;
1721 spin_unlock(&inode
->i_lock
);
1723 for (index
= start
; index
< end
; index
++) {
1727 * Good, the fallocate(2) manpage permits EINTR: we may have
1728 * been interrupted because we are using up too much memory.
1730 if (signal_pending(current
))
1732 else if (shmem_falloc
.nr_unswapped
> shmem_falloc
.nr_falloced
)
1735 error
= shmem_getpage(inode
, index
, &page
, SGP_FALLOC
,
1738 /* Remove the !PageUptodate pages we added */
1739 shmem_undo_range(inode
,
1740 (loff_t
)start
<< PAGE_CACHE_SHIFT
,
1741 (loff_t
)index
<< PAGE_CACHE_SHIFT
, true);
1746 * Inform shmem_writepage() how far we have reached.
1747 * No need for lock or barrier: we have the page lock.
1749 shmem_falloc
.next
++;
1750 if (!PageUptodate(page
))
1751 shmem_falloc
.nr_falloced
++;
1754 * If !PageUptodate, leave it that way so that freeable pages
1755 * can be recognized if we need to rollback on error later.
1756 * But set_page_dirty so that memory pressure will swap rather
1757 * than free the pages we are allocating (and SGP_CACHE pages
1758 * might still be clean: we now need to mark those dirty too).
1760 set_page_dirty(page
);
1762 page_cache_release(page
);
1766 if (!(mode
& FALLOC_FL_KEEP_SIZE
) && offset
+ len
> inode
->i_size
)
1767 i_size_write(inode
, offset
+ len
);
1768 inode
->i_ctime
= CURRENT_TIME
;
1770 spin_lock(&inode
->i_lock
);
1771 inode
->i_private
= NULL
;
1772 spin_unlock(&inode
->i_lock
);
1774 mutex_unlock(&inode
->i_mutex
);
1778 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1780 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1782 buf
->f_type
= TMPFS_MAGIC
;
1783 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1784 buf
->f_namelen
= NAME_MAX
;
1785 if (sbinfo
->max_blocks
) {
1786 buf
->f_blocks
= sbinfo
->max_blocks
;
1788 buf
->f_bfree
= sbinfo
->max_blocks
-
1789 percpu_counter_sum(&sbinfo
->used_blocks
);
1791 if (sbinfo
->max_inodes
) {
1792 buf
->f_files
= sbinfo
->max_inodes
;
1793 buf
->f_ffree
= sbinfo
->free_inodes
;
1795 /* else leave those fields 0 like simple_statfs */
1800 * File creation. Allocate an inode, and we're done..
1803 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
1805 struct inode
*inode
;
1806 int error
= -ENOSPC
;
1808 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, dev
, VM_NORESERVE
);
1810 error
= security_inode_init_security(inode
, dir
,
1812 shmem_initxattrs
, NULL
);
1814 if (error
!= -EOPNOTSUPP
) {
1819 #ifdef CONFIG_TMPFS_POSIX_ACL
1820 error
= generic_acl_init(inode
, dir
);
1828 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1829 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1830 d_instantiate(dentry
, inode
);
1831 dget(dentry
); /* Extra count - pin the dentry in core */
1836 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
1840 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1846 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
1847 struct nameidata
*nd
)
1849 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
1855 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
1857 struct inode
*inode
= old_dentry
->d_inode
;
1861 * No ordinary (disk based) filesystem counts links as inodes;
1862 * but each new link needs a new dentry, pinning lowmem, and
1863 * tmpfs dentries cannot be pruned until they are unlinked.
1865 ret
= shmem_reserve_inode(inode
->i_sb
);
1869 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1870 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1872 ihold(inode
); /* New dentry reference */
1873 dget(dentry
); /* Extra pinning count for the created dentry */
1874 d_instantiate(dentry
, inode
);
1879 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
1881 struct inode
*inode
= dentry
->d_inode
;
1883 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
1884 shmem_free_inode(inode
->i_sb
);
1886 dir
->i_size
-= BOGO_DIRENT_SIZE
;
1887 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1889 dput(dentry
); /* Undo the count from "create" - this does all the work */
1893 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
1895 if (!simple_empty(dentry
))
1898 drop_nlink(dentry
->d_inode
);
1900 return shmem_unlink(dir
, dentry
);
1904 * The VFS layer already does all the dentry stuff for rename,
1905 * we just have to decrement the usage count for the target if
1906 * it exists so that the VFS layer correctly free's it when it
1909 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
1911 struct inode
*inode
= old_dentry
->d_inode
;
1912 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
1914 if (!simple_empty(new_dentry
))
1917 if (new_dentry
->d_inode
) {
1918 (void) shmem_unlink(new_dir
, new_dentry
);
1920 drop_nlink(old_dir
);
1921 } else if (they_are_dirs
) {
1922 drop_nlink(old_dir
);
1926 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
1927 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
1928 old_dir
->i_ctime
= old_dir
->i_mtime
=
1929 new_dir
->i_ctime
= new_dir
->i_mtime
=
1930 inode
->i_ctime
= CURRENT_TIME
;
1934 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
1938 struct inode
*inode
;
1941 struct shmem_inode_info
*info
;
1943 len
= strlen(symname
) + 1;
1944 if (len
> PAGE_CACHE_SIZE
)
1945 return -ENAMETOOLONG
;
1947 inode
= shmem_get_inode(dir
->i_sb
, dir
, S_IFLNK
|S_IRWXUGO
, 0, VM_NORESERVE
);
1951 error
= security_inode_init_security(inode
, dir
, &dentry
->d_name
,
1952 shmem_initxattrs
, NULL
);
1954 if (error
!= -EOPNOTSUPP
) {
1961 info
= SHMEM_I(inode
);
1962 inode
->i_size
= len
-1;
1963 if (len
<= SHORT_SYMLINK_LEN
) {
1964 info
->symlink
= kmemdup(symname
, len
, GFP_KERNEL
);
1965 if (!info
->symlink
) {
1969 inode
->i_op
= &shmem_short_symlink_operations
;
1971 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
1976 inode
->i_mapping
->a_ops
= &shmem_aops
;
1977 inode
->i_op
= &shmem_symlink_inode_operations
;
1978 kaddr
= kmap_atomic(page
);
1979 memcpy(kaddr
, symname
, len
);
1980 kunmap_atomic(kaddr
);
1981 SetPageUptodate(page
);
1982 set_page_dirty(page
);
1984 page_cache_release(page
);
1986 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1987 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1988 d_instantiate(dentry
, inode
);
1993 static void *shmem_follow_short_symlink(struct dentry
*dentry
, struct nameidata
*nd
)
1995 nd_set_link(nd
, SHMEM_I(dentry
->d_inode
)->symlink
);
1999 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
2001 struct page
*page
= NULL
;
2002 int error
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
2003 nd_set_link(nd
, error
? ERR_PTR(error
) : kmap(page
));
2009 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2011 if (!IS_ERR(nd_get_link(nd
))) {
2012 struct page
*page
= cookie
;
2014 mark_page_accessed(page
);
2015 page_cache_release(page
);
2019 #ifdef CONFIG_TMPFS_XATTR
2021 * Superblocks without xattr inode operations may get some security.* xattr
2022 * support from the LSM "for free". As soon as we have any other xattrs
2023 * like ACLs, we also need to implement the security.* handlers at
2024 * filesystem level, though.
2028 * Allocate new xattr and copy in the value; but leave the name to callers.
2030 static struct shmem_xattr
*shmem_xattr_alloc(const void *value
, size_t size
)
2032 struct shmem_xattr
*new_xattr
;
2036 len
= sizeof(*new_xattr
) + size
;
2037 if (len
<= sizeof(*new_xattr
))
2040 new_xattr
= kmalloc(len
, GFP_KERNEL
);
2044 new_xattr
->size
= size
;
2045 memcpy(new_xattr
->value
, value
, size
);
2050 * Callback for security_inode_init_security() for acquiring xattrs.
2052 static int shmem_initxattrs(struct inode
*inode
,
2053 const struct xattr
*xattr_array
,
2056 struct shmem_inode_info
*info
= SHMEM_I(inode
);
2057 const struct xattr
*xattr
;
2058 struct shmem_xattr
*new_xattr
;
2061 for (xattr
= xattr_array
; xattr
->name
!= NULL
; xattr
++) {
2062 new_xattr
= shmem_xattr_alloc(xattr
->value
, xattr
->value_len
);
2066 len
= strlen(xattr
->name
) + 1;
2067 new_xattr
->name
= kmalloc(XATTR_SECURITY_PREFIX_LEN
+ len
,
2069 if (!new_xattr
->name
) {
2074 memcpy(new_xattr
->name
, XATTR_SECURITY_PREFIX
,
2075 XATTR_SECURITY_PREFIX_LEN
);
2076 memcpy(new_xattr
->name
+ XATTR_SECURITY_PREFIX_LEN
,
2079 spin_lock(&info
->lock
);
2080 list_add(&new_xattr
->list
, &info
->xattr_list
);
2081 spin_unlock(&info
->lock
);
2087 static int shmem_xattr_get(struct dentry
*dentry
, const char *name
,
2088 void *buffer
, size_t size
)
2090 struct shmem_inode_info
*info
;
2091 struct shmem_xattr
*xattr
;
2094 info
= SHMEM_I(dentry
->d_inode
);
2096 spin_lock(&info
->lock
);
2097 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
2098 if (strcmp(name
, xattr
->name
))
2103 if (size
< xattr
->size
)
2106 memcpy(buffer
, xattr
->value
, xattr
->size
);
2110 spin_unlock(&info
->lock
);
2114 static int shmem_xattr_set(struct inode
*inode
, const char *name
,
2115 const void *value
, size_t size
, int flags
)
2117 struct shmem_inode_info
*info
= SHMEM_I(inode
);
2118 struct shmem_xattr
*xattr
;
2119 struct shmem_xattr
*new_xattr
= NULL
;
2122 /* value == NULL means remove */
2124 new_xattr
= shmem_xattr_alloc(value
, size
);
2128 new_xattr
->name
= kstrdup(name
, GFP_KERNEL
);
2129 if (!new_xattr
->name
) {
2135 spin_lock(&info
->lock
);
2136 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
2137 if (!strcmp(name
, xattr
->name
)) {
2138 if (flags
& XATTR_CREATE
) {
2141 } else if (new_xattr
) {
2142 list_replace(&xattr
->list
, &new_xattr
->list
);
2144 list_del(&xattr
->list
);
2149 if (flags
& XATTR_REPLACE
) {
2153 list_add(&new_xattr
->list
, &info
->xattr_list
);
2157 spin_unlock(&info
->lock
);
2164 static const struct xattr_handler
*shmem_xattr_handlers
[] = {
2165 #ifdef CONFIG_TMPFS_POSIX_ACL
2166 &generic_acl_access_handler
,
2167 &generic_acl_default_handler
,
2172 static int shmem_xattr_validate(const char *name
)
2174 struct { const char *prefix
; size_t len
; } arr
[] = {
2175 { XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
},
2176 { XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
}
2180 for (i
= 0; i
< ARRAY_SIZE(arr
); i
++) {
2181 size_t preflen
= arr
[i
].len
;
2182 if (strncmp(name
, arr
[i
].prefix
, preflen
) == 0) {
2191 static ssize_t
shmem_getxattr(struct dentry
*dentry
, const char *name
,
2192 void *buffer
, size_t size
)
2197 * If this is a request for a synthetic attribute in the system.*
2198 * namespace use the generic infrastructure to resolve a handler
2199 * for it via sb->s_xattr.
2201 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2202 return generic_getxattr(dentry
, name
, buffer
, size
);
2204 err
= shmem_xattr_validate(name
);
2208 return shmem_xattr_get(dentry
, name
, buffer
, size
);
2211 static int shmem_setxattr(struct dentry
*dentry
, const char *name
,
2212 const void *value
, size_t size
, int flags
)
2217 * If this is a request for a synthetic attribute in the system.*
2218 * namespace use the generic infrastructure to resolve a handler
2219 * for it via sb->s_xattr.
2221 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2222 return generic_setxattr(dentry
, name
, value
, size
, flags
);
2224 err
= shmem_xattr_validate(name
);
2229 value
= ""; /* empty EA, do not remove */
2231 return shmem_xattr_set(dentry
->d_inode
, name
, value
, size
, flags
);
2235 static int shmem_removexattr(struct dentry
*dentry
, const char *name
)
2240 * If this is a request for a synthetic attribute in the system.*
2241 * namespace use the generic infrastructure to resolve a handler
2242 * for it via sb->s_xattr.
2244 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2245 return generic_removexattr(dentry
, name
);
2247 err
= shmem_xattr_validate(name
);
2251 return shmem_xattr_set(dentry
->d_inode
, name
, NULL
, 0, XATTR_REPLACE
);
2254 static bool xattr_is_trusted(const char *name
)
2256 return !strncmp(name
, XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
);
2259 static ssize_t
shmem_listxattr(struct dentry
*dentry
, char *buffer
, size_t size
)
2261 bool trusted
= capable(CAP_SYS_ADMIN
);
2262 struct shmem_xattr
*xattr
;
2263 struct shmem_inode_info
*info
;
2266 info
= SHMEM_I(dentry
->d_inode
);
2268 spin_lock(&info
->lock
);
2269 list_for_each_entry(xattr
, &info
->xattr_list
, list
) {
2272 /* skip "trusted." attributes for unprivileged callers */
2273 if (!trusted
&& xattr_is_trusted(xattr
->name
))
2276 len
= strlen(xattr
->name
) + 1;
2283 memcpy(buffer
, xattr
->name
, len
);
2287 spin_unlock(&info
->lock
);
2291 #endif /* CONFIG_TMPFS_XATTR */
2293 static const struct inode_operations shmem_short_symlink_operations
= {
2294 .readlink
= generic_readlink
,
2295 .follow_link
= shmem_follow_short_symlink
,
2296 #ifdef CONFIG_TMPFS_XATTR
2297 .setxattr
= shmem_setxattr
,
2298 .getxattr
= shmem_getxattr
,
2299 .listxattr
= shmem_listxattr
,
2300 .removexattr
= shmem_removexattr
,
2304 static const struct inode_operations shmem_symlink_inode_operations
= {
2305 .readlink
= generic_readlink
,
2306 .follow_link
= shmem_follow_link
,
2307 .put_link
= shmem_put_link
,
2308 #ifdef CONFIG_TMPFS_XATTR
2309 .setxattr
= shmem_setxattr
,
2310 .getxattr
= shmem_getxattr
,
2311 .listxattr
= shmem_listxattr
,
2312 .removexattr
= shmem_removexattr
,
2316 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2318 return ERR_PTR(-ESTALE
);
2321 static int shmem_match(struct inode
*ino
, void *vfh
)
2325 inum
= (inum
<< 32) | fh
[1];
2326 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2329 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
2330 struct fid
*fid
, int fh_len
, int fh_type
)
2332 struct inode
*inode
;
2333 struct dentry
*dentry
= NULL
;
2334 u64 inum
= fid
->raw
[2];
2335 inum
= (inum
<< 32) | fid
->raw
[1];
2340 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
2341 shmem_match
, fid
->raw
);
2343 dentry
= d_find_alias(inode
);
2350 static int shmem_encode_fh(struct dentry
*dentry
, __u32
*fh
, int *len
,
2353 struct inode
*inode
= dentry
->d_inode
;
2360 if (inode_unhashed(inode
)) {
2361 /* Unfortunately insert_inode_hash is not idempotent,
2362 * so as we hash inodes here rather than at creation
2363 * time, we need a lock to ensure we only try
2366 static DEFINE_SPINLOCK(lock
);
2368 if (inode_unhashed(inode
))
2369 __insert_inode_hash(inode
,
2370 inode
->i_ino
+ inode
->i_generation
);
2374 fh
[0] = inode
->i_generation
;
2375 fh
[1] = inode
->i_ino
;
2376 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2382 static const struct export_operations shmem_export_ops
= {
2383 .get_parent
= shmem_get_parent
,
2384 .encode_fh
= shmem_encode_fh
,
2385 .fh_to_dentry
= shmem_fh_to_dentry
,
2388 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2391 char *this_char
, *value
, *rest
;
2395 while (options
!= NULL
) {
2396 this_char
= options
;
2399 * NUL-terminate this option: unfortunately,
2400 * mount options form a comma-separated list,
2401 * but mpol's nodelist may also contain commas.
2403 options
= strchr(options
, ',');
2404 if (options
== NULL
)
2407 if (!isdigit(*options
)) {
2414 if ((value
= strchr(this_char
,'=')) != NULL
) {
2418 "tmpfs: No value for mount option '%s'\n",
2423 if (!strcmp(this_char
,"size")) {
2424 unsigned long long size
;
2425 size
= memparse(value
,&rest
);
2427 size
<<= PAGE_SHIFT
;
2428 size
*= totalram_pages
;
2434 sbinfo
->max_blocks
=
2435 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2436 } else if (!strcmp(this_char
,"nr_blocks")) {
2437 sbinfo
->max_blocks
= memparse(value
, &rest
);
2440 } else if (!strcmp(this_char
,"nr_inodes")) {
2441 sbinfo
->max_inodes
= memparse(value
, &rest
);
2444 } else if (!strcmp(this_char
,"mode")) {
2447 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2450 } else if (!strcmp(this_char
,"uid")) {
2453 uid
= simple_strtoul(value
, &rest
, 0);
2456 sbinfo
->uid
= make_kuid(current_user_ns(), uid
);
2457 if (!uid_valid(sbinfo
->uid
))
2459 } else if (!strcmp(this_char
,"gid")) {
2462 gid
= simple_strtoul(value
, &rest
, 0);
2465 sbinfo
->gid
= make_kgid(current_user_ns(), gid
);
2466 if (!gid_valid(sbinfo
->gid
))
2468 } else if (!strcmp(this_char
,"mpol")) {
2469 if (mpol_parse_str(value
, &sbinfo
->mpol
, 1))
2472 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2480 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2486 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2488 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2489 struct shmem_sb_info config
= *sbinfo
;
2490 unsigned long inodes
;
2491 int error
= -EINVAL
;
2493 if (shmem_parse_options(data
, &config
, true))
2496 spin_lock(&sbinfo
->stat_lock
);
2497 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2498 if (percpu_counter_compare(&sbinfo
->used_blocks
, config
.max_blocks
) > 0)
2500 if (config
.max_inodes
< inodes
)
2503 * Those tests disallow limited->unlimited while any are in use;
2504 * but we must separately disallow unlimited->limited, because
2505 * in that case we have no record of how much is already in use.
2507 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2509 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2513 sbinfo
->max_blocks
= config
.max_blocks
;
2514 sbinfo
->max_inodes
= config
.max_inodes
;
2515 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2517 mpol_put(sbinfo
->mpol
);
2518 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2520 spin_unlock(&sbinfo
->stat_lock
);
2524 static int shmem_show_options(struct seq_file
*seq
, struct dentry
*root
)
2526 struct shmem_sb_info
*sbinfo
= SHMEM_SB(root
->d_sb
);
2528 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2529 seq_printf(seq
, ",size=%luk",
2530 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2531 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2532 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2533 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2534 seq_printf(seq
, ",mode=%03ho", sbinfo
->mode
);
2535 if (!uid_eq(sbinfo
->uid
, GLOBAL_ROOT_UID
))
2536 seq_printf(seq
, ",uid=%u",
2537 from_kuid_munged(&init_user_ns
, sbinfo
->uid
));
2538 if (!gid_eq(sbinfo
->gid
, GLOBAL_ROOT_GID
))
2539 seq_printf(seq
, ",gid=%u",
2540 from_kgid_munged(&init_user_ns
, sbinfo
->gid
));
2541 shmem_show_mpol(seq
, sbinfo
->mpol
);
2544 #endif /* CONFIG_TMPFS */
2546 static void shmem_put_super(struct super_block
*sb
)
2548 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2550 percpu_counter_destroy(&sbinfo
->used_blocks
);
2552 sb
->s_fs_info
= NULL
;
2555 int shmem_fill_super(struct super_block
*sb
, void *data
, int silent
)
2557 struct inode
*inode
;
2558 struct shmem_sb_info
*sbinfo
;
2561 /* Round up to L1_CACHE_BYTES to resist false sharing */
2562 sbinfo
= kzalloc(max((int)sizeof(struct shmem_sb_info
),
2563 L1_CACHE_BYTES
), GFP_KERNEL
);
2567 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2568 sbinfo
->uid
= current_fsuid();
2569 sbinfo
->gid
= current_fsgid();
2570 sb
->s_fs_info
= sbinfo
;
2574 * Per default we only allow half of the physical ram per
2575 * tmpfs instance, limiting inodes to one per page of lowmem;
2576 * but the internal instance is left unlimited.
2578 if (!(sb
->s_flags
& MS_NOUSER
)) {
2579 sbinfo
->max_blocks
= shmem_default_max_blocks();
2580 sbinfo
->max_inodes
= shmem_default_max_inodes();
2581 if (shmem_parse_options(data
, sbinfo
, false)) {
2586 sb
->s_export_op
= &shmem_export_ops
;
2587 sb
->s_flags
|= MS_NOSEC
;
2589 sb
->s_flags
|= MS_NOUSER
;
2592 spin_lock_init(&sbinfo
->stat_lock
);
2593 if (percpu_counter_init(&sbinfo
->used_blocks
, 0))
2595 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2597 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
2598 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2599 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2600 sb
->s_magic
= TMPFS_MAGIC
;
2601 sb
->s_op
= &shmem_ops
;
2602 sb
->s_time_gran
= 1;
2603 #ifdef CONFIG_TMPFS_XATTR
2604 sb
->s_xattr
= shmem_xattr_handlers
;
2606 #ifdef CONFIG_TMPFS_POSIX_ACL
2607 sb
->s_flags
|= MS_POSIXACL
;
2610 inode
= shmem_get_inode(sb
, NULL
, S_IFDIR
| sbinfo
->mode
, 0, VM_NORESERVE
);
2613 inode
->i_uid
= sbinfo
->uid
;
2614 inode
->i_gid
= sbinfo
->gid
;
2615 sb
->s_root
= d_make_root(inode
);
2621 shmem_put_super(sb
);
2625 static struct kmem_cache
*shmem_inode_cachep
;
2627 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2629 struct shmem_inode_info
*info
;
2630 info
= kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2633 return &info
->vfs_inode
;
2636 static void shmem_destroy_callback(struct rcu_head
*head
)
2638 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
2639 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2642 static void shmem_destroy_inode(struct inode
*inode
)
2644 if (S_ISREG(inode
->i_mode
))
2645 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2646 call_rcu(&inode
->i_rcu
, shmem_destroy_callback
);
2649 static void shmem_init_inode(void *foo
)
2651 struct shmem_inode_info
*info
= foo
;
2652 inode_init_once(&info
->vfs_inode
);
2655 static int shmem_init_inodecache(void)
2657 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2658 sizeof(struct shmem_inode_info
),
2659 0, SLAB_PANIC
, shmem_init_inode
);
2663 static void shmem_destroy_inodecache(void)
2665 kmem_cache_destroy(shmem_inode_cachep
);
2668 static const struct address_space_operations shmem_aops
= {
2669 .writepage
= shmem_writepage
,
2670 .set_page_dirty
= __set_page_dirty_no_writeback
,
2672 .write_begin
= shmem_write_begin
,
2673 .write_end
= shmem_write_end
,
2675 .migratepage
= migrate_page
,
2676 .error_remove_page
= generic_error_remove_page
,
2679 static const struct file_operations shmem_file_operations
= {
2682 .llseek
= generic_file_llseek
,
2683 .read
= do_sync_read
,
2684 .write
= do_sync_write
,
2685 .aio_read
= shmem_file_aio_read
,
2686 .aio_write
= generic_file_aio_write
,
2687 .fsync
= noop_fsync
,
2688 .splice_read
= shmem_file_splice_read
,
2689 .splice_write
= generic_file_splice_write
,
2690 .fallocate
= shmem_fallocate
,
2694 static const struct inode_operations shmem_inode_operations
= {
2695 .setattr
= shmem_setattr
,
2696 #ifdef CONFIG_TMPFS_XATTR
2697 .setxattr
= shmem_setxattr
,
2698 .getxattr
= shmem_getxattr
,
2699 .listxattr
= shmem_listxattr
,
2700 .removexattr
= shmem_removexattr
,
2704 static const struct inode_operations shmem_dir_inode_operations
= {
2706 .create
= shmem_create
,
2707 .lookup
= simple_lookup
,
2709 .unlink
= shmem_unlink
,
2710 .symlink
= shmem_symlink
,
2711 .mkdir
= shmem_mkdir
,
2712 .rmdir
= shmem_rmdir
,
2713 .mknod
= shmem_mknod
,
2714 .rename
= shmem_rename
,
2716 #ifdef CONFIG_TMPFS_XATTR
2717 .setxattr
= shmem_setxattr
,
2718 .getxattr
= shmem_getxattr
,
2719 .listxattr
= shmem_listxattr
,
2720 .removexattr
= shmem_removexattr
,
2722 #ifdef CONFIG_TMPFS_POSIX_ACL
2723 .setattr
= shmem_setattr
,
2727 static const struct inode_operations shmem_special_inode_operations
= {
2728 #ifdef CONFIG_TMPFS_XATTR
2729 .setxattr
= shmem_setxattr
,
2730 .getxattr
= shmem_getxattr
,
2731 .listxattr
= shmem_listxattr
,
2732 .removexattr
= shmem_removexattr
,
2734 #ifdef CONFIG_TMPFS_POSIX_ACL
2735 .setattr
= shmem_setattr
,
2739 static const struct super_operations shmem_ops
= {
2740 .alloc_inode
= shmem_alloc_inode
,
2741 .destroy_inode
= shmem_destroy_inode
,
2743 .statfs
= shmem_statfs
,
2744 .remount_fs
= shmem_remount_fs
,
2745 .show_options
= shmem_show_options
,
2747 .evict_inode
= shmem_evict_inode
,
2748 .drop_inode
= generic_delete_inode
,
2749 .put_super
= shmem_put_super
,
2752 static const struct vm_operations_struct shmem_vm_ops
= {
2753 .fault
= shmem_fault
,
2755 .set_policy
= shmem_set_policy
,
2756 .get_policy
= shmem_get_policy
,
2760 static struct dentry
*shmem_mount(struct file_system_type
*fs_type
,
2761 int flags
, const char *dev_name
, void *data
)
2763 return mount_nodev(fs_type
, flags
, data
, shmem_fill_super
);
2766 static struct file_system_type shmem_fs_type
= {
2767 .owner
= THIS_MODULE
,
2769 .mount
= shmem_mount
,
2770 .kill_sb
= kill_litter_super
,
2773 int __init
shmem_init(void)
2777 error
= bdi_init(&shmem_backing_dev_info
);
2781 error
= shmem_init_inodecache();
2785 error
= register_filesystem(&shmem_fs_type
);
2787 printk(KERN_ERR
"Could not register tmpfs\n");
2791 shm_mnt
= vfs_kern_mount(&shmem_fs_type
, MS_NOUSER
,
2792 shmem_fs_type
.name
, NULL
);
2793 if (IS_ERR(shm_mnt
)) {
2794 error
= PTR_ERR(shm_mnt
);
2795 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2801 unregister_filesystem(&shmem_fs_type
);
2803 shmem_destroy_inodecache();
2805 bdi_destroy(&shmem_backing_dev_info
);
2807 shm_mnt
= ERR_PTR(error
);
2811 #else /* !CONFIG_SHMEM */
2814 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2816 * This is intended for small system where the benefits of the full
2817 * shmem code (swap-backed and resource-limited) are outweighed by
2818 * their complexity. On systems without swap this code should be
2819 * effectively equivalent, but much lighter weight.
2822 #include <linux/ramfs.h>
2824 static struct file_system_type shmem_fs_type
= {
2826 .mount
= ramfs_mount
,
2827 .kill_sb
= kill_litter_super
,
2830 int __init
shmem_init(void)
2832 BUG_ON(register_filesystem(&shmem_fs_type
) != 0);
2834 shm_mnt
= kern_mount(&shmem_fs_type
);
2835 BUG_ON(IS_ERR(shm_mnt
));
2840 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
2845 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
2850 void shmem_unlock_mapping(struct address_space
*mapping
)
2854 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
2856 truncate_inode_pages_range(inode
->i_mapping
, lstart
, lend
);
2858 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
2860 #define shmem_vm_ops generic_file_vm_ops
2861 #define shmem_file_operations ramfs_file_operations
2862 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2863 #define shmem_acct_size(flags, size) 0
2864 #define shmem_unacct_size(flags, size) do {} while (0)
2866 #endif /* CONFIG_SHMEM */
2871 * shmem_file_setup - get an unlinked file living in tmpfs
2872 * @name: name for dentry (to be seen in /proc/<pid>/maps
2873 * @size: size to be set for the file
2874 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2876 struct file
*shmem_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2880 struct inode
*inode
;
2882 struct dentry
*root
;
2885 if (IS_ERR(shm_mnt
))
2886 return (void *)shm_mnt
;
2888 if (size
< 0 || size
> MAX_LFS_FILESIZE
)
2889 return ERR_PTR(-EINVAL
);
2891 if (shmem_acct_size(flags
, size
))
2892 return ERR_PTR(-ENOMEM
);
2896 this.len
= strlen(name
);
2897 this.hash
= 0; /* will go */
2898 root
= shm_mnt
->mnt_root
;
2899 path
.dentry
= d_alloc(root
, &this);
2902 path
.mnt
= mntget(shm_mnt
);
2905 inode
= shmem_get_inode(root
->d_sb
, NULL
, S_IFREG
| S_IRWXUGO
, 0, flags
);
2909 d_instantiate(path
.dentry
, inode
);
2910 inode
->i_size
= size
;
2911 clear_nlink(inode
); /* It is unlinked */
2913 error
= ramfs_nommu_expand_for_mapping(inode
, size
);
2919 file
= alloc_file(&path
, FMODE_WRITE
| FMODE_READ
,
2920 &shmem_file_operations
);
2929 shmem_unacct_size(flags
, size
);
2930 return ERR_PTR(error
);
2932 EXPORT_SYMBOL_GPL(shmem_file_setup
);
2935 * shmem_zero_setup - setup a shared anonymous mapping
2936 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2938 int shmem_zero_setup(struct vm_area_struct
*vma
)
2941 loff_t size
= vma
->vm_end
- vma
->vm_start
;
2943 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
2945 return PTR_ERR(file
);
2949 vma
->vm_file
= file
;
2950 vma
->vm_ops
= &shmem_vm_ops
;
2951 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
2956 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
2957 * @mapping: the page's address_space
2958 * @index: the page index
2959 * @gfp: the page allocator flags to use if allocating
2961 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
2962 * with any new page allocations done using the specified allocation flags.
2963 * But read_cache_page_gfp() uses the ->readpage() method: which does not
2964 * suit tmpfs, since it may have pages in swapcache, and needs to find those
2965 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
2967 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
2968 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
2970 struct page
*shmem_read_mapping_page_gfp(struct address_space
*mapping
,
2971 pgoff_t index
, gfp_t gfp
)
2974 struct inode
*inode
= mapping
->host
;
2978 BUG_ON(mapping
->a_ops
!= &shmem_aops
);
2979 error
= shmem_getpage_gfp(inode
, index
, &page
, SGP_CACHE
, gfp
, NULL
);
2981 page
= ERR_PTR(error
);
2987 * The tiny !SHMEM case uses ramfs without swap
2989 return read_cache_page_gfp(mapping
, index
, gfp
);
2992 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp
);