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/ramfs.h>
29 #include <linux/pagemap.h>
30 #include <linux/file.h>
32 #include <linux/export.h>
33 #include <linux/swap.h>
34 #include <linux/aio.h>
36 static struct vfsmount
*shm_mnt
;
40 * This virtual memory filesystem is heavily based on the ramfs. It
41 * extends ramfs by the ability to use swap and honor resource limits
42 * which makes it a completely usable filesystem.
45 #include <linux/xattr.h>
46 #include <linux/exportfs.h>
47 #include <linux/posix_acl.h>
48 #include <linux/posix_acl_xattr.h>
49 #include <linux/mman.h>
50 #include <linux/string.h>
51 #include <linux/slab.h>
52 #include <linux/backing-dev.h>
53 #include <linux/shmem_fs.h>
54 #include <linux/writeback.h>
55 #include <linux/blkdev.h>
56 #include <linux/pagevec.h>
57 #include <linux/percpu_counter.h>
58 #include <linux/falloc.h>
59 #include <linux/splice.h>
60 #include <linux/security.h>
61 #include <linux/swapops.h>
62 #include <linux/mempolicy.h>
63 #include <linux/namei.h>
64 #include <linux/ctype.h>
65 #include <linux/migrate.h>
66 #include <linux/highmem.h>
67 #include <linux/seq_file.h>
68 #include <linux/magic.h>
70 #include <asm/uaccess.h>
71 #include <asm/pgtable.h>
73 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
74 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
76 /* Pretend that each entry is of this size in directory's i_size */
77 #define BOGO_DIRENT_SIZE 20
79 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
80 #define SHORT_SYMLINK_LEN 128
83 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
84 * inode->i_private (with i_mutex making sure that it has only one user at
85 * a time): we would prefer not to enlarge the shmem inode just for that.
88 wait_queue_head_t
*waitq
; /* faults into hole wait for punch to end */
89 pgoff_t start
; /* start of range currently being fallocated */
90 pgoff_t next
; /* the next page offset to be fallocated */
91 pgoff_t nr_falloced
; /* how many new pages have been fallocated */
92 pgoff_t nr_unswapped
; /* how often writepage refused to swap out */
95 /* Flag allocation requirements to shmem_getpage */
97 SGP_READ
, /* don't exceed i_size, don't allocate page */
98 SGP_CACHE
, /* don't exceed i_size, may allocate page */
99 SGP_DIRTY
, /* like SGP_CACHE, but set new page dirty */
100 SGP_WRITE
, /* may exceed i_size, may allocate !Uptodate page */
101 SGP_FALLOC
, /* like SGP_WRITE, but make existing page Uptodate */
105 static unsigned long shmem_default_max_blocks(void)
107 return totalram_pages
/ 2;
110 static unsigned long shmem_default_max_inodes(void)
112 return min(totalram_pages
- totalhigh_pages
, totalram_pages
/ 2);
116 static bool shmem_should_replace_page(struct page
*page
, gfp_t gfp
);
117 static int shmem_replace_page(struct page
**pagep
, gfp_t gfp
,
118 struct shmem_inode_info
*info
, pgoff_t index
);
119 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
120 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
);
122 static inline int shmem_getpage(struct inode
*inode
, pgoff_t index
,
123 struct page
**pagep
, enum sgp_type sgp
, int *fault_type
)
125 return shmem_getpage_gfp(inode
, index
, pagep
, sgp
,
126 mapping_gfp_mask(inode
->i_mapping
), fault_type
);
129 static inline struct shmem_sb_info
*SHMEM_SB(struct super_block
*sb
)
131 return sb
->s_fs_info
;
135 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
136 * for shared memory and for shared anonymous (/dev/zero) mappings
137 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
138 * consistent with the pre-accounting of private mappings ...
140 static inline int shmem_acct_size(unsigned long flags
, loff_t size
)
142 return (flags
& VM_NORESERVE
) ?
143 0 : security_vm_enough_memory_mm(current
->mm
, VM_ACCT(size
));
146 static inline void shmem_unacct_size(unsigned long flags
, loff_t size
)
148 if (!(flags
& VM_NORESERVE
))
149 vm_unacct_memory(VM_ACCT(size
));
153 * ... whereas tmpfs objects are accounted incrementally as
154 * pages are allocated, in order to allow huge sparse files.
155 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
156 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
158 static inline int shmem_acct_block(unsigned long flags
)
160 return (flags
& VM_NORESERVE
) ?
161 security_vm_enough_memory_mm(current
->mm
, VM_ACCT(PAGE_CACHE_SIZE
)) : 0;
164 static inline void shmem_unacct_blocks(unsigned long flags
, long pages
)
166 if (flags
& VM_NORESERVE
)
167 vm_unacct_memory(pages
* VM_ACCT(PAGE_CACHE_SIZE
));
170 static const struct super_operations shmem_ops
;
171 static const struct address_space_operations shmem_aops
;
172 static const struct file_operations shmem_file_operations
;
173 static const struct inode_operations shmem_inode_operations
;
174 static const struct inode_operations shmem_dir_inode_operations
;
175 static const struct inode_operations shmem_special_inode_operations
;
176 static const struct vm_operations_struct shmem_vm_ops
;
178 static struct backing_dev_info shmem_backing_dev_info __read_mostly
= {
179 .ra_pages
= 0, /* No readahead */
180 .capabilities
= BDI_CAP_NO_ACCT_AND_WRITEBACK
| BDI_CAP_SWAP_BACKED
,
183 static LIST_HEAD(shmem_swaplist
);
184 static DEFINE_MUTEX(shmem_swaplist_mutex
);
186 static int shmem_reserve_inode(struct super_block
*sb
)
188 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
189 if (sbinfo
->max_inodes
) {
190 spin_lock(&sbinfo
->stat_lock
);
191 if (!sbinfo
->free_inodes
) {
192 spin_unlock(&sbinfo
->stat_lock
);
195 sbinfo
->free_inodes
--;
196 spin_unlock(&sbinfo
->stat_lock
);
201 static void shmem_free_inode(struct super_block
*sb
)
203 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
204 if (sbinfo
->max_inodes
) {
205 spin_lock(&sbinfo
->stat_lock
);
206 sbinfo
->free_inodes
++;
207 spin_unlock(&sbinfo
->stat_lock
);
212 * shmem_recalc_inode - recalculate the block usage of an inode
213 * @inode: inode to recalc
215 * We have to calculate the free blocks since the mm can drop
216 * undirtied hole pages behind our back.
218 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
219 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
221 * It has to be called with the spinlock held.
223 static void shmem_recalc_inode(struct inode
*inode
)
225 struct shmem_inode_info
*info
= SHMEM_I(inode
);
228 freed
= info
->alloced
- info
->swapped
- inode
->i_mapping
->nrpages
;
230 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
231 if (sbinfo
->max_blocks
)
232 percpu_counter_add(&sbinfo
->used_blocks
, -freed
);
233 info
->alloced
-= freed
;
234 inode
->i_blocks
-= freed
* BLOCKS_PER_PAGE
;
235 shmem_unacct_blocks(info
->flags
, freed
);
240 * Replace item expected in radix tree by a new item, while holding tree lock.
242 static int shmem_radix_tree_replace(struct address_space
*mapping
,
243 pgoff_t index
, void *expected
, void *replacement
)
248 VM_BUG_ON(!expected
);
249 VM_BUG_ON(!replacement
);
250 pslot
= radix_tree_lookup_slot(&mapping
->page_tree
, index
);
253 item
= radix_tree_deref_slot_protected(pslot
, &mapping
->tree_lock
);
254 if (item
!= expected
)
256 radix_tree_replace_slot(pslot
, replacement
);
261 * Sometimes, before we decide whether to proceed or to fail, we must check
262 * that an entry was not already brought back from swap by a racing thread.
264 * Checking page is not enough: by the time a SwapCache page is locked, it
265 * might be reused, and again be SwapCache, using the same swap as before.
267 static bool shmem_confirm_swap(struct address_space
*mapping
,
268 pgoff_t index
, swp_entry_t swap
)
273 item
= radix_tree_lookup(&mapping
->page_tree
, index
);
275 return item
== swp_to_radix_entry(swap
);
279 * Like add_to_page_cache_locked, but error if expected item has gone.
281 static int shmem_add_to_page_cache(struct page
*page
,
282 struct address_space
*mapping
,
283 pgoff_t index
, gfp_t gfp
, void *expected
)
287 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
288 VM_BUG_ON_PAGE(!PageSwapBacked(page
), page
);
290 page_cache_get(page
);
291 page
->mapping
= mapping
;
294 spin_lock_irq(&mapping
->tree_lock
);
296 error
= radix_tree_insert(&mapping
->page_tree
, index
, page
);
298 error
= shmem_radix_tree_replace(mapping
, index
, expected
,
302 __inc_zone_page_state(page
, NR_FILE_PAGES
);
303 __inc_zone_page_state(page
, NR_SHMEM
);
304 spin_unlock_irq(&mapping
->tree_lock
);
306 page
->mapping
= NULL
;
307 spin_unlock_irq(&mapping
->tree_lock
);
308 page_cache_release(page
);
314 * Like delete_from_page_cache, but substitutes swap for page.
316 static void shmem_delete_from_page_cache(struct page
*page
, void *radswap
)
318 struct address_space
*mapping
= page
->mapping
;
321 spin_lock_irq(&mapping
->tree_lock
);
322 error
= shmem_radix_tree_replace(mapping
, page
->index
, page
, radswap
);
323 page
->mapping
= NULL
;
325 __dec_zone_page_state(page
, NR_FILE_PAGES
);
326 __dec_zone_page_state(page
, NR_SHMEM
);
327 spin_unlock_irq(&mapping
->tree_lock
);
328 page_cache_release(page
);
333 * Remove swap entry from radix tree, free the swap and its page cache.
335 static int shmem_free_swap(struct address_space
*mapping
,
336 pgoff_t index
, void *radswap
)
340 spin_lock_irq(&mapping
->tree_lock
);
341 old
= radix_tree_delete_item(&mapping
->page_tree
, index
, radswap
);
342 spin_unlock_irq(&mapping
->tree_lock
);
345 free_swap_and_cache(radix_to_swp_entry(radswap
));
350 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
352 void shmem_unlock_mapping(struct address_space
*mapping
)
355 pgoff_t indices
[PAGEVEC_SIZE
];
358 pagevec_init(&pvec
, 0);
360 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
362 while (!mapping_unevictable(mapping
)) {
364 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
365 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
367 pvec
.nr
= find_get_entries(mapping
, index
,
368 PAGEVEC_SIZE
, pvec
.pages
, indices
);
371 index
= indices
[pvec
.nr
- 1] + 1;
372 pagevec_remove_exceptionals(&pvec
);
373 check_move_unevictable_pages(pvec
.pages
, pvec
.nr
);
374 pagevec_release(&pvec
);
380 * Remove range of pages and swap entries from radix tree, and free them.
381 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
383 static void shmem_undo_range(struct inode
*inode
, loff_t lstart
, loff_t lend
,
386 struct address_space
*mapping
= inode
->i_mapping
;
387 struct shmem_inode_info
*info
= SHMEM_I(inode
);
388 pgoff_t start
= (lstart
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
389 pgoff_t end
= (lend
+ 1) >> PAGE_CACHE_SHIFT
;
390 unsigned int partial_start
= lstart
& (PAGE_CACHE_SIZE
- 1);
391 unsigned int partial_end
= (lend
+ 1) & (PAGE_CACHE_SIZE
- 1);
393 pgoff_t indices
[PAGEVEC_SIZE
];
394 long nr_swaps_freed
= 0;
399 end
= -1; /* unsigned, so actually very big */
401 pagevec_init(&pvec
, 0);
403 while (index
< end
) {
404 pvec
.nr
= find_get_entries(mapping
, index
,
405 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
),
406 pvec
.pages
, indices
);
409 mem_cgroup_uncharge_start();
410 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
411 struct page
*page
= pvec
.pages
[i
];
417 if (radix_tree_exceptional_entry(page
)) {
420 nr_swaps_freed
+= !shmem_free_swap(mapping
,
425 if (!trylock_page(page
))
427 if (!unfalloc
|| !PageUptodate(page
)) {
428 if (page
->mapping
== mapping
) {
429 VM_BUG_ON_PAGE(PageWriteback(page
), page
);
430 truncate_inode_page(mapping
, page
);
435 pagevec_remove_exceptionals(&pvec
);
436 pagevec_release(&pvec
);
437 mem_cgroup_uncharge_end();
443 struct page
*page
= NULL
;
444 shmem_getpage(inode
, start
- 1, &page
, SGP_READ
, NULL
);
446 unsigned int top
= PAGE_CACHE_SIZE
;
451 zero_user_segment(page
, partial_start
, top
);
452 set_page_dirty(page
);
454 page_cache_release(page
);
458 struct page
*page
= NULL
;
459 shmem_getpage(inode
, end
, &page
, SGP_READ
, NULL
);
461 zero_user_segment(page
, 0, partial_end
);
462 set_page_dirty(page
);
464 page_cache_release(page
);
471 while (index
< end
) {
474 pvec
.nr
= find_get_entries(mapping
, index
,
475 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
),
476 pvec
.pages
, indices
);
478 /* If all gone or hole-punch or unfalloc, we're done */
479 if (index
== start
|| end
!= -1)
481 /* But if truncating, restart to make sure all gone */
485 mem_cgroup_uncharge_start();
486 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
487 struct page
*page
= pvec
.pages
[i
];
493 if (radix_tree_exceptional_entry(page
)) {
496 if (shmem_free_swap(mapping
, index
, page
)) {
497 /* Swap was replaced by page: retry */
506 if (!unfalloc
|| !PageUptodate(page
)) {
507 if (page
->mapping
== mapping
) {
508 VM_BUG_ON_PAGE(PageWriteback(page
), page
);
509 truncate_inode_page(mapping
, page
);
511 /* Page was replaced by swap: retry */
519 pagevec_remove_exceptionals(&pvec
);
520 pagevec_release(&pvec
);
521 mem_cgroup_uncharge_end();
525 spin_lock(&info
->lock
);
526 info
->swapped
-= nr_swaps_freed
;
527 shmem_recalc_inode(inode
);
528 spin_unlock(&info
->lock
);
531 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
533 shmem_undo_range(inode
, lstart
, lend
, false);
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 if (attr
->ia_valid
& ATTR_MODE
)
566 error
= posix_acl_chmod(inode
, inode
->i_mode
);
570 static void shmem_evict_inode(struct inode
*inode
)
572 struct shmem_inode_info
*info
= SHMEM_I(inode
);
574 if (inode
->i_mapping
->a_ops
== &shmem_aops
) {
575 shmem_unacct_size(info
->flags
, inode
->i_size
);
577 shmem_truncate_range(inode
, 0, (loff_t
)-1);
578 if (!list_empty(&info
->swaplist
)) {
579 mutex_lock(&shmem_swaplist_mutex
);
580 list_del_init(&info
->swaplist
);
581 mutex_unlock(&shmem_swaplist_mutex
);
584 kfree(info
->symlink
);
586 simple_xattrs_free(&info
->xattrs
);
587 WARN_ON(inode
->i_blocks
);
588 shmem_free_inode(inode
->i_sb
);
593 * If swap found in inode, free it and move page from swapcache to filecache.
595 static int shmem_unuse_inode(struct shmem_inode_info
*info
,
596 swp_entry_t swap
, struct page
**pagep
)
598 struct address_space
*mapping
= info
->vfs_inode
.i_mapping
;
604 radswap
= swp_to_radix_entry(swap
);
605 index
= radix_tree_locate_item(&mapping
->page_tree
, radswap
);
610 * Move _head_ to start search for next from here.
611 * But be careful: shmem_evict_inode checks list_empty without taking
612 * mutex, and there's an instant in list_move_tail when info->swaplist
613 * would appear empty, if it were the only one on shmem_swaplist.
615 if (shmem_swaplist
.next
!= &info
->swaplist
)
616 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
618 gfp
= mapping_gfp_mask(mapping
);
619 if (shmem_should_replace_page(*pagep
, gfp
)) {
620 mutex_unlock(&shmem_swaplist_mutex
);
621 error
= shmem_replace_page(pagep
, gfp
, info
, index
);
622 mutex_lock(&shmem_swaplist_mutex
);
624 * We needed to drop mutex to make that restrictive page
625 * allocation, but the inode might have been freed while we
626 * dropped it: although a racing shmem_evict_inode() cannot
627 * complete without emptying the radix_tree, our page lock
628 * on this swapcache page is not enough to prevent that -
629 * free_swap_and_cache() of our swap entry will only
630 * trylock_page(), removing swap from radix_tree whatever.
632 * We must not proceed to shmem_add_to_page_cache() if the
633 * inode has been freed, but of course we cannot rely on
634 * inode or mapping or info to check that. However, we can
635 * safely check if our swap entry is still in use (and here
636 * it can't have got reused for another page): if it's still
637 * in use, then the inode cannot have been freed yet, and we
638 * can safely proceed (if it's no longer in use, that tells
639 * nothing about the inode, but we don't need to unuse swap).
641 if (!page_swapcount(*pagep
))
646 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
647 * but also to hold up shmem_evict_inode(): so inode cannot be freed
648 * beneath us (pagelock doesn't help until the page is in pagecache).
651 error
= shmem_add_to_page_cache(*pagep
, mapping
, index
,
652 GFP_NOWAIT
, radswap
);
653 if (error
!= -ENOMEM
) {
655 * Truncation and eviction use free_swap_and_cache(), which
656 * only does trylock page: if we raced, best clean up here.
658 delete_from_swap_cache(*pagep
);
659 set_page_dirty(*pagep
);
661 spin_lock(&info
->lock
);
663 spin_unlock(&info
->lock
);
666 error
= 1; /* not an error, but entry was found */
672 * Search through swapped inodes to find and replace swap by page.
674 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
676 struct list_head
*this, *next
;
677 struct shmem_inode_info
*info
;
682 * There's a faint possibility that swap page was replaced before
683 * caller locked it: caller will come back later with the right page.
685 if (unlikely(!PageSwapCache(page
) || page_private(page
) != swap
.val
))
689 * Charge page using GFP_KERNEL while we can wait, before taking
690 * the shmem_swaplist_mutex which might hold up shmem_writepage().
691 * Charged back to the user (not to caller) when swap account is used.
693 error
= mem_cgroup_charge_file(page
, current
->mm
, GFP_KERNEL
);
696 /* No radix_tree_preload: swap entry keeps a place for page in tree */
698 mutex_lock(&shmem_swaplist_mutex
);
699 list_for_each_safe(this, next
, &shmem_swaplist
) {
700 info
= list_entry(this, struct shmem_inode_info
, swaplist
);
702 found
= shmem_unuse_inode(info
, swap
, &page
);
704 list_del_init(&info
->swaplist
);
709 mutex_unlock(&shmem_swaplist_mutex
);
715 page_cache_release(page
);
720 * Move the page from the page cache to the swap cache.
722 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
724 struct shmem_inode_info
*info
;
725 struct address_space
*mapping
;
730 BUG_ON(!PageLocked(page
));
731 mapping
= page
->mapping
;
733 inode
= mapping
->host
;
734 info
= SHMEM_I(inode
);
735 if (info
->flags
& VM_LOCKED
)
737 if (!total_swap_pages
)
741 * shmem_backing_dev_info's capabilities prevent regular writeback or
742 * sync from ever calling shmem_writepage; but a stacking filesystem
743 * might use ->writepage of its underlying filesystem, in which case
744 * tmpfs should write out to swap only in response to memory pressure,
745 * and not for the writeback threads or sync.
747 if (!wbc
->for_reclaim
) {
748 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
753 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
754 * value into swapfile.c, the only way we can correctly account for a
755 * fallocated page arriving here is now to initialize it and write it.
757 * That's okay for a page already fallocated earlier, but if we have
758 * not yet completed the fallocation, then (a) we want to keep track
759 * of this page in case we have to undo it, and (b) it may not be a
760 * good idea to continue anyway, once we're pushing into swap. So
761 * reactivate the page, and let shmem_fallocate() quit when too many.
763 if (!PageUptodate(page
)) {
764 if (inode
->i_private
) {
765 struct shmem_falloc
*shmem_falloc
;
766 spin_lock(&inode
->i_lock
);
767 shmem_falloc
= inode
->i_private
;
769 !shmem_falloc
->waitq
&&
770 index
>= shmem_falloc
->start
&&
771 index
< shmem_falloc
->next
)
772 shmem_falloc
->nr_unswapped
++;
775 spin_unlock(&inode
->i_lock
);
779 clear_highpage(page
);
780 flush_dcache_page(page
);
781 SetPageUptodate(page
);
784 swap
= get_swap_page();
789 * Add inode to shmem_unuse()'s list of swapped-out inodes,
790 * if it's not already there. Do it now before the page is
791 * moved to swap cache, when its pagelock no longer protects
792 * the inode from eviction. But don't unlock the mutex until
793 * we've incremented swapped, because shmem_unuse_inode() will
794 * prune a !swapped inode from the swaplist under this mutex.
796 mutex_lock(&shmem_swaplist_mutex
);
797 if (list_empty(&info
->swaplist
))
798 list_add_tail(&info
->swaplist
, &shmem_swaplist
);
800 if (add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
801 swap_shmem_alloc(swap
);
802 shmem_delete_from_page_cache(page
, swp_to_radix_entry(swap
));
804 spin_lock(&info
->lock
);
806 shmem_recalc_inode(inode
);
807 spin_unlock(&info
->lock
);
809 mutex_unlock(&shmem_swaplist_mutex
);
810 BUG_ON(page_mapped(page
));
811 swap_writepage(page
, wbc
);
815 mutex_unlock(&shmem_swaplist_mutex
);
816 swapcache_free(swap
, NULL
);
818 set_page_dirty(page
);
819 if (wbc
->for_reclaim
)
820 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
827 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
831 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
832 return; /* show nothing */
834 mpol_to_str(buffer
, sizeof(buffer
), mpol
);
836 seq_printf(seq
, ",mpol=%s", buffer
);
839 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
841 struct mempolicy
*mpol
= NULL
;
843 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
846 spin_unlock(&sbinfo
->stat_lock
);
850 #endif /* CONFIG_TMPFS */
852 static struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
853 struct shmem_inode_info
*info
, pgoff_t index
)
855 struct vm_area_struct pvma
;
858 /* Create a pseudo vma that just contains the policy */
860 /* Bias interleave by inode number to distribute better across nodes */
861 pvma
.vm_pgoff
= index
+ info
->vfs_inode
.i_ino
;
863 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, index
);
865 page
= swapin_readahead(swap
, gfp
, &pvma
, 0);
867 /* Drop reference taken by mpol_shared_policy_lookup() */
868 mpol_cond_put(pvma
.vm_policy
);
873 static struct page
*shmem_alloc_page(gfp_t gfp
,
874 struct shmem_inode_info
*info
, pgoff_t index
)
876 struct vm_area_struct pvma
;
879 /* Create a pseudo vma that just contains the policy */
881 /* Bias interleave by inode number to distribute better across nodes */
882 pvma
.vm_pgoff
= index
+ info
->vfs_inode
.i_ino
;
884 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, index
);
886 page
= alloc_page_vma(gfp
, &pvma
, 0);
888 /* Drop reference taken by mpol_shared_policy_lookup() */
889 mpol_cond_put(pvma
.vm_policy
);
893 #else /* !CONFIG_NUMA */
895 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
898 #endif /* CONFIG_TMPFS */
900 static inline struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
901 struct shmem_inode_info
*info
, pgoff_t index
)
903 return swapin_readahead(swap
, gfp
, NULL
, 0);
906 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
907 struct shmem_inode_info
*info
, pgoff_t index
)
909 return alloc_page(gfp
);
911 #endif /* CONFIG_NUMA */
913 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
914 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
921 * When a page is moved from swapcache to shmem filecache (either by the
922 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
923 * shmem_unuse_inode()), it may have been read in earlier from swap, in
924 * ignorance of the mapping it belongs to. If that mapping has special
925 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
926 * we may need to copy to a suitable page before moving to filecache.
928 * In a future release, this may well be extended to respect cpuset and
929 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
930 * but for now it is a simple matter of zone.
932 static bool shmem_should_replace_page(struct page
*page
, gfp_t gfp
)
934 return page_zonenum(page
) > gfp_zone(gfp
);
937 static int shmem_replace_page(struct page
**pagep
, gfp_t gfp
,
938 struct shmem_inode_info
*info
, pgoff_t index
)
940 struct page
*oldpage
, *newpage
;
941 struct address_space
*swap_mapping
;
946 swap_index
= page_private(oldpage
);
947 swap_mapping
= page_mapping(oldpage
);
950 * We have arrived here because our zones are constrained, so don't
951 * limit chance of success by further cpuset and node constraints.
953 gfp
&= ~GFP_CONSTRAINT_MASK
;
954 newpage
= shmem_alloc_page(gfp
, info
, index
);
958 page_cache_get(newpage
);
959 copy_highpage(newpage
, oldpage
);
960 flush_dcache_page(newpage
);
962 __set_page_locked(newpage
);
963 SetPageUptodate(newpage
);
964 SetPageSwapBacked(newpage
);
965 set_page_private(newpage
, swap_index
);
966 SetPageSwapCache(newpage
);
969 * Our caller will very soon move newpage out of swapcache, but it's
970 * a nice clean interface for us to replace oldpage by newpage there.
972 spin_lock_irq(&swap_mapping
->tree_lock
);
973 error
= shmem_radix_tree_replace(swap_mapping
, swap_index
, oldpage
,
976 __inc_zone_page_state(newpage
, NR_FILE_PAGES
);
977 __dec_zone_page_state(oldpage
, NR_FILE_PAGES
);
979 spin_unlock_irq(&swap_mapping
->tree_lock
);
981 if (unlikely(error
)) {
983 * Is this possible? I think not, now that our callers check
984 * both PageSwapCache and page_private after getting page lock;
985 * but be defensive. Reverse old to newpage for clear and free.
989 mem_cgroup_replace_page_cache(oldpage
, newpage
);
990 lru_cache_add_anon(newpage
);
994 ClearPageSwapCache(oldpage
);
995 set_page_private(oldpage
, 0);
997 unlock_page(oldpage
);
998 page_cache_release(oldpage
);
999 page_cache_release(oldpage
);
1004 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1006 * If we allocate a new one we do not mark it dirty. That's up to the
1007 * vm. If we swap it in we mark it dirty since we also free the swap
1008 * entry since a page cannot live in both the swap and page cache
1010 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
1011 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
)
1013 struct address_space
*mapping
= inode
->i_mapping
;
1014 struct shmem_inode_info
*info
;
1015 struct shmem_sb_info
*sbinfo
;
1022 if (index
> (MAX_LFS_FILESIZE
>> PAGE_CACHE_SHIFT
))
1026 page
= find_lock_entry(mapping
, index
);
1027 if (radix_tree_exceptional_entry(page
)) {
1028 swap
= radix_to_swp_entry(page
);
1032 if (sgp
!= SGP_WRITE
&& sgp
!= SGP_FALLOC
&&
1033 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1038 if (page
&& sgp
== SGP_WRITE
)
1039 mark_page_accessed(page
);
1041 /* fallocated page? */
1042 if (page
&& !PageUptodate(page
)) {
1043 if (sgp
!= SGP_READ
)
1046 page_cache_release(page
);
1049 if (page
|| (sgp
== SGP_READ
&& !swap
.val
)) {
1055 * Fast cache lookup did not find it:
1056 * bring it back from swap or allocate.
1058 info
= SHMEM_I(inode
);
1059 sbinfo
= SHMEM_SB(inode
->i_sb
);
1062 /* Look it up and read it in.. */
1063 page
= lookup_swap_cache(swap
);
1065 /* here we actually do the io */
1067 *fault_type
|= VM_FAULT_MAJOR
;
1068 page
= shmem_swapin(swap
, gfp
, info
, index
);
1075 /* We have to do this with page locked to prevent races */
1077 if (!PageSwapCache(page
) || page_private(page
) != swap
.val
||
1078 !shmem_confirm_swap(mapping
, index
, swap
)) {
1079 error
= -EEXIST
; /* try again */
1082 if (!PageUptodate(page
)) {
1086 wait_on_page_writeback(page
);
1088 if (shmem_should_replace_page(page
, gfp
)) {
1089 error
= shmem_replace_page(&page
, gfp
, info
, index
);
1094 error
= mem_cgroup_charge_file(page
, current
->mm
,
1095 gfp
& GFP_RECLAIM_MASK
);
1097 error
= shmem_add_to_page_cache(page
, mapping
, index
,
1098 gfp
, swp_to_radix_entry(swap
));
1100 * We already confirmed swap under page lock, and make
1101 * no memory allocation here, so usually no possibility
1102 * of error; but free_swap_and_cache() only trylocks a
1103 * page, so it is just possible that the entry has been
1104 * truncated or holepunched since swap was confirmed.
1105 * shmem_undo_range() will have done some of the
1106 * unaccounting, now delete_from_swap_cache() will do
1107 * the rest (including mem_cgroup_uncharge_swapcache).
1108 * Reset swap.val? No, leave it so "failed" goes back to
1109 * "repeat": reading a hole and writing should succeed.
1112 delete_from_swap_cache(page
);
1117 spin_lock(&info
->lock
);
1119 shmem_recalc_inode(inode
);
1120 spin_unlock(&info
->lock
);
1122 if (sgp
== SGP_WRITE
)
1123 mark_page_accessed(page
);
1125 delete_from_swap_cache(page
);
1126 set_page_dirty(page
);
1130 if (shmem_acct_block(info
->flags
)) {
1134 if (sbinfo
->max_blocks
) {
1135 if (percpu_counter_compare(&sbinfo
->used_blocks
,
1136 sbinfo
->max_blocks
) >= 0) {
1140 percpu_counter_inc(&sbinfo
->used_blocks
);
1143 page
= shmem_alloc_page(gfp
, info
, index
);
1149 __SetPageSwapBacked(page
);
1150 __set_page_locked(page
);
1151 if (sgp
== SGP_WRITE
)
1152 init_page_accessed(page
);
1154 error
= mem_cgroup_charge_file(page
, current
->mm
,
1155 gfp
& GFP_RECLAIM_MASK
);
1158 error
= radix_tree_maybe_preload(gfp
& GFP_RECLAIM_MASK
);
1160 error
= shmem_add_to_page_cache(page
, mapping
, index
,
1162 radix_tree_preload_end();
1165 mem_cgroup_uncharge_cache_page(page
);
1168 lru_cache_add_anon(page
);
1170 spin_lock(&info
->lock
);
1172 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1173 shmem_recalc_inode(inode
);
1174 spin_unlock(&info
->lock
);
1178 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1180 if (sgp
== SGP_FALLOC
)
1184 * Let SGP_WRITE caller clear ends if write does not fill page;
1185 * but SGP_FALLOC on a page fallocated earlier must initialize
1186 * it now, lest undo on failure cancel our earlier guarantee.
1188 if (sgp
!= SGP_WRITE
) {
1189 clear_highpage(page
);
1190 flush_dcache_page(page
);
1191 SetPageUptodate(page
);
1193 if (sgp
== SGP_DIRTY
)
1194 set_page_dirty(page
);
1197 /* Perhaps the file has been truncated since we checked */
1198 if (sgp
!= SGP_WRITE
&& sgp
!= SGP_FALLOC
&&
1199 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1213 info
= SHMEM_I(inode
);
1214 ClearPageDirty(page
);
1215 delete_from_page_cache(page
);
1216 spin_lock(&info
->lock
);
1218 inode
->i_blocks
-= BLOCKS_PER_PAGE
;
1219 spin_unlock(&info
->lock
);
1221 sbinfo
= SHMEM_SB(inode
->i_sb
);
1222 if (sbinfo
->max_blocks
)
1223 percpu_counter_add(&sbinfo
->used_blocks
, -1);
1225 shmem_unacct_blocks(info
->flags
, 1);
1227 if (swap
.val
&& error
!= -EINVAL
&&
1228 !shmem_confirm_swap(mapping
, index
, swap
))
1233 page_cache_release(page
);
1235 if (error
== -ENOSPC
&& !once
++) {
1236 info
= SHMEM_I(inode
);
1237 spin_lock(&info
->lock
);
1238 shmem_recalc_inode(inode
);
1239 spin_unlock(&info
->lock
);
1242 if (error
== -EEXIST
) /* from above or from radix_tree_insert */
1247 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1249 struct inode
*inode
= file_inode(vma
->vm_file
);
1251 int ret
= VM_FAULT_LOCKED
;
1254 * Trinity finds that probing a hole which tmpfs is punching can
1255 * prevent the hole-punch from ever completing: which in turn
1256 * locks writers out with its hold on i_mutex. So refrain from
1257 * faulting pages into the hole while it's being punched. Although
1258 * shmem_undo_range() does remove the additions, it may be unable to
1259 * keep up, as each new page needs its own unmap_mapping_range() call,
1260 * and the i_mmap tree grows ever slower to scan if new vmas are added.
1262 * It does not matter if we sometimes reach this check just before the
1263 * hole-punch begins, so that one fault then races with the punch:
1264 * we just need to make racing faults a rare case.
1266 * The implementation below would be much simpler if we just used a
1267 * standard mutex or completion: but we cannot take i_mutex in fault,
1268 * and bloating every shmem inode for this unlikely case would be sad.
1270 if (unlikely(inode
->i_private
)) {
1271 struct shmem_falloc
*shmem_falloc
;
1273 spin_lock(&inode
->i_lock
);
1274 shmem_falloc
= inode
->i_private
;
1276 shmem_falloc
->waitq
&&
1277 vmf
->pgoff
>= shmem_falloc
->start
&&
1278 vmf
->pgoff
< shmem_falloc
->next
) {
1279 wait_queue_head_t
*shmem_falloc_waitq
;
1280 DEFINE_WAIT(shmem_fault_wait
);
1282 ret
= VM_FAULT_NOPAGE
;
1283 if ((vmf
->flags
& FAULT_FLAG_ALLOW_RETRY
) &&
1284 !(vmf
->flags
& FAULT_FLAG_RETRY_NOWAIT
)) {
1285 /* It's polite to up mmap_sem if we can */
1286 up_read(&vma
->vm_mm
->mmap_sem
);
1287 ret
= VM_FAULT_RETRY
;
1290 shmem_falloc_waitq
= shmem_falloc
->waitq
;
1291 prepare_to_wait(shmem_falloc_waitq
, &shmem_fault_wait
,
1292 TASK_UNINTERRUPTIBLE
);
1293 spin_unlock(&inode
->i_lock
);
1297 * shmem_falloc_waitq points into the shmem_fallocate()
1298 * stack of the hole-punching task: shmem_falloc_waitq
1299 * is usually invalid by the time we reach here, but
1300 * finish_wait() does not dereference it in that case;
1301 * though i_lock needed lest racing with wake_up_all().
1303 spin_lock(&inode
->i_lock
);
1304 finish_wait(shmem_falloc_waitq
, &shmem_fault_wait
);
1305 spin_unlock(&inode
->i_lock
);
1308 spin_unlock(&inode
->i_lock
);
1311 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1313 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1315 if (ret
& VM_FAULT_MAJOR
) {
1316 count_vm_event(PGMAJFAULT
);
1317 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1323 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*mpol
)
1325 struct inode
*inode
= file_inode(vma
->vm_file
);
1326 return mpol_set_shared_policy(&SHMEM_I(inode
)->policy
, vma
, mpol
);
1329 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1332 struct inode
*inode
= file_inode(vma
->vm_file
);
1335 index
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1336 return mpol_shared_policy_lookup(&SHMEM_I(inode
)->policy
, index
);
1340 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1342 struct inode
*inode
= file_inode(file
);
1343 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1344 int retval
= -ENOMEM
;
1346 spin_lock(&info
->lock
);
1347 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1348 if (!user_shm_lock(inode
->i_size
, user
))
1350 info
->flags
|= VM_LOCKED
;
1351 mapping_set_unevictable(file
->f_mapping
);
1353 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1354 user_shm_unlock(inode
->i_size
, user
);
1355 info
->flags
&= ~VM_LOCKED
;
1356 mapping_clear_unevictable(file
->f_mapping
);
1361 spin_unlock(&info
->lock
);
1365 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1367 file_accessed(file
);
1368 vma
->vm_ops
= &shmem_vm_ops
;
1372 static struct inode
*shmem_get_inode(struct super_block
*sb
, const struct inode
*dir
,
1373 umode_t mode
, dev_t dev
, unsigned long flags
)
1375 struct inode
*inode
;
1376 struct shmem_inode_info
*info
;
1377 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1379 if (shmem_reserve_inode(sb
))
1382 inode
= new_inode(sb
);
1384 inode
->i_ino
= get_next_ino();
1385 inode_init_owner(inode
, dir
, mode
);
1386 inode
->i_blocks
= 0;
1387 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1388 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1389 inode
->i_generation
= get_seconds();
1390 info
= SHMEM_I(inode
);
1391 memset(info
, 0, (char *)inode
- (char *)info
);
1392 spin_lock_init(&info
->lock
);
1393 info
->flags
= flags
& VM_NORESERVE
;
1394 INIT_LIST_HEAD(&info
->swaplist
);
1395 simple_xattrs_init(&info
->xattrs
);
1396 cache_no_acl(inode
);
1398 switch (mode
& S_IFMT
) {
1400 inode
->i_op
= &shmem_special_inode_operations
;
1401 init_special_inode(inode
, mode
, dev
);
1404 inode
->i_mapping
->a_ops
= &shmem_aops
;
1405 inode
->i_op
= &shmem_inode_operations
;
1406 inode
->i_fop
= &shmem_file_operations
;
1407 mpol_shared_policy_init(&info
->policy
,
1408 shmem_get_sbmpol(sbinfo
));
1412 /* Some things misbehave if size == 0 on a directory */
1413 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1414 inode
->i_op
= &shmem_dir_inode_operations
;
1415 inode
->i_fop
= &simple_dir_operations
;
1419 * Must not load anything in the rbtree,
1420 * mpol_free_shared_policy will not be called.
1422 mpol_shared_policy_init(&info
->policy
, NULL
);
1426 shmem_free_inode(sb
);
1430 bool shmem_mapping(struct address_space
*mapping
)
1432 return mapping
->backing_dev_info
== &shmem_backing_dev_info
;
1436 static const struct inode_operations shmem_symlink_inode_operations
;
1437 static const struct inode_operations shmem_short_symlink_operations
;
1439 #ifdef CONFIG_TMPFS_XATTR
1440 static int shmem_initxattrs(struct inode
*, const struct xattr
*, void *);
1442 #define shmem_initxattrs NULL
1446 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1447 loff_t pos
, unsigned len
, unsigned flags
,
1448 struct page
**pagep
, void **fsdata
)
1450 struct inode
*inode
= mapping
->host
;
1451 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1452 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1456 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1457 loff_t pos
, unsigned len
, unsigned copied
,
1458 struct page
*page
, void *fsdata
)
1460 struct inode
*inode
= mapping
->host
;
1462 if (pos
+ copied
> inode
->i_size
)
1463 i_size_write(inode
, pos
+ copied
);
1465 if (!PageUptodate(page
)) {
1466 if (copied
< PAGE_CACHE_SIZE
) {
1467 unsigned from
= pos
& (PAGE_CACHE_SIZE
- 1);
1468 zero_user_segments(page
, 0, from
,
1469 from
+ copied
, PAGE_CACHE_SIZE
);
1471 SetPageUptodate(page
);
1473 set_page_dirty(page
);
1475 page_cache_release(page
);
1480 static ssize_t
shmem_file_read_iter(struct kiocb
*iocb
, struct iov_iter
*to
)
1482 struct file
*file
= iocb
->ki_filp
;
1483 struct inode
*inode
= file_inode(file
);
1484 struct address_space
*mapping
= inode
->i_mapping
;
1486 unsigned long offset
;
1487 enum sgp_type sgp
= SGP_READ
;
1490 loff_t
*ppos
= &iocb
->ki_pos
;
1493 * Might this read be for a stacking filesystem? Then when reading
1494 * holes of a sparse file, we actually need to allocate those pages,
1495 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1497 if (segment_eq(get_fs(), KERNEL_DS
))
1500 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1501 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1504 struct page
*page
= NULL
;
1506 unsigned long nr
, ret
;
1507 loff_t i_size
= i_size_read(inode
);
1509 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1510 if (index
> end_index
)
1512 if (index
== end_index
) {
1513 nr
= i_size
& ~PAGE_CACHE_MASK
;
1518 error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1520 if (error
== -EINVAL
)
1528 * We must evaluate after, since reads (unlike writes)
1529 * are called without i_mutex protection against truncate
1531 nr
= PAGE_CACHE_SIZE
;
1532 i_size
= i_size_read(inode
);
1533 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1534 if (index
== end_index
) {
1535 nr
= i_size
& ~PAGE_CACHE_MASK
;
1538 page_cache_release(page
);
1546 * If users can be writing to this page using arbitrary
1547 * virtual addresses, take care about potential aliasing
1548 * before reading the page on the kernel side.
1550 if (mapping_writably_mapped(mapping
))
1551 flush_dcache_page(page
);
1553 * Mark the page accessed if we read the beginning.
1556 mark_page_accessed(page
);
1558 page
= ZERO_PAGE(0);
1559 page_cache_get(page
);
1563 * Ok, we have the page, and it's up-to-date, so
1564 * now we can copy it to user space...
1566 ret
= copy_page_to_iter(page
, offset
, nr
, to
);
1569 index
+= offset
>> PAGE_CACHE_SHIFT
;
1570 offset
&= ~PAGE_CACHE_MASK
;
1572 page_cache_release(page
);
1573 if (!iov_iter_count(to
))
1582 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1583 file_accessed(file
);
1584 return retval
? retval
: error
;
1587 static ssize_t
shmem_file_splice_read(struct file
*in
, loff_t
*ppos
,
1588 struct pipe_inode_info
*pipe
, size_t len
,
1591 struct address_space
*mapping
= in
->f_mapping
;
1592 struct inode
*inode
= mapping
->host
;
1593 unsigned int loff
, nr_pages
, req_pages
;
1594 struct page
*pages
[PIPE_DEF_BUFFERS
];
1595 struct partial_page partial
[PIPE_DEF_BUFFERS
];
1597 pgoff_t index
, end_index
;
1600 struct splice_pipe_desc spd
= {
1603 .nr_pages_max
= PIPE_DEF_BUFFERS
,
1605 .ops
= &page_cache_pipe_buf_ops
,
1606 .spd_release
= spd_release_page
,
1609 isize
= i_size_read(inode
);
1610 if (unlikely(*ppos
>= isize
))
1613 left
= isize
- *ppos
;
1614 if (unlikely(left
< len
))
1617 if (splice_grow_spd(pipe
, &spd
))
1620 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1621 loff
= *ppos
& ~PAGE_CACHE_MASK
;
1622 req_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1623 nr_pages
= min(req_pages
, spd
.nr_pages_max
);
1625 spd
.nr_pages
= find_get_pages_contig(mapping
, index
,
1626 nr_pages
, spd
.pages
);
1627 index
+= spd
.nr_pages
;
1630 while (spd
.nr_pages
< nr_pages
) {
1631 error
= shmem_getpage(inode
, index
, &page
, SGP_CACHE
, NULL
);
1635 spd
.pages
[spd
.nr_pages
++] = page
;
1639 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1640 nr_pages
= spd
.nr_pages
;
1643 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
1644 unsigned int this_len
;
1649 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
1650 page
= spd
.pages
[page_nr
];
1652 if (!PageUptodate(page
) || page
->mapping
!= mapping
) {
1653 error
= shmem_getpage(inode
, index
, &page
,
1658 page_cache_release(spd
.pages
[page_nr
]);
1659 spd
.pages
[page_nr
] = page
;
1662 isize
= i_size_read(inode
);
1663 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1664 if (unlikely(!isize
|| index
> end_index
))
1667 if (end_index
== index
) {
1670 plen
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1674 this_len
= min(this_len
, plen
- loff
);
1678 spd
.partial
[page_nr
].offset
= loff
;
1679 spd
.partial
[page_nr
].len
= this_len
;
1686 while (page_nr
< nr_pages
)
1687 page_cache_release(spd
.pages
[page_nr
++]);
1690 error
= splice_to_pipe(pipe
, &spd
);
1692 splice_shrink_spd(&spd
);
1702 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
1704 static pgoff_t
shmem_seek_hole_data(struct address_space
*mapping
,
1705 pgoff_t index
, pgoff_t end
, int whence
)
1708 struct pagevec pvec
;
1709 pgoff_t indices
[PAGEVEC_SIZE
];
1713 pagevec_init(&pvec
, 0);
1714 pvec
.nr
= 1; /* start small: we may be there already */
1716 pvec
.nr
= find_get_entries(mapping
, index
,
1717 pvec
.nr
, pvec
.pages
, indices
);
1719 if (whence
== SEEK_DATA
)
1723 for (i
= 0; i
< pvec
.nr
; i
++, index
++) {
1724 if (index
< indices
[i
]) {
1725 if (whence
== SEEK_HOLE
) {
1731 page
= pvec
.pages
[i
];
1732 if (page
&& !radix_tree_exceptional_entry(page
)) {
1733 if (!PageUptodate(page
))
1737 (page
&& whence
== SEEK_DATA
) ||
1738 (!page
&& whence
== SEEK_HOLE
)) {
1743 pagevec_remove_exceptionals(&pvec
);
1744 pagevec_release(&pvec
);
1745 pvec
.nr
= PAGEVEC_SIZE
;
1751 static loff_t
shmem_file_llseek(struct file
*file
, loff_t offset
, int whence
)
1753 struct address_space
*mapping
= file
->f_mapping
;
1754 struct inode
*inode
= mapping
->host
;
1758 if (whence
!= SEEK_DATA
&& whence
!= SEEK_HOLE
)
1759 return generic_file_llseek_size(file
, offset
, whence
,
1760 MAX_LFS_FILESIZE
, i_size_read(inode
));
1761 mutex_lock(&inode
->i_mutex
);
1762 /* We're holding i_mutex so we can access i_size directly */
1766 else if (offset
>= inode
->i_size
)
1769 start
= offset
>> PAGE_CACHE_SHIFT
;
1770 end
= (inode
->i_size
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1771 new_offset
= shmem_seek_hole_data(mapping
, start
, end
, whence
);
1772 new_offset
<<= PAGE_CACHE_SHIFT
;
1773 if (new_offset
> offset
) {
1774 if (new_offset
< inode
->i_size
)
1775 offset
= new_offset
;
1776 else if (whence
== SEEK_DATA
)
1779 offset
= inode
->i_size
;
1784 offset
= vfs_setpos(file
, offset
, MAX_LFS_FILESIZE
);
1785 mutex_unlock(&inode
->i_mutex
);
1789 static long shmem_fallocate(struct file
*file
, int mode
, loff_t offset
,
1792 struct inode
*inode
= file_inode(file
);
1793 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
1794 struct shmem_falloc shmem_falloc
;
1795 pgoff_t start
, index
, end
;
1798 if (mode
& ~(FALLOC_FL_KEEP_SIZE
| FALLOC_FL_PUNCH_HOLE
))
1801 mutex_lock(&inode
->i_mutex
);
1803 if (mode
& FALLOC_FL_PUNCH_HOLE
) {
1804 struct address_space
*mapping
= file
->f_mapping
;
1805 loff_t unmap_start
= round_up(offset
, PAGE_SIZE
);
1806 loff_t unmap_end
= round_down(offset
+ len
, PAGE_SIZE
) - 1;
1807 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq
);
1809 shmem_falloc
.waitq
= &shmem_falloc_waitq
;
1810 shmem_falloc
.start
= unmap_start
>> PAGE_SHIFT
;
1811 shmem_falloc
.next
= (unmap_end
+ 1) >> PAGE_SHIFT
;
1812 spin_lock(&inode
->i_lock
);
1813 inode
->i_private
= &shmem_falloc
;
1814 spin_unlock(&inode
->i_lock
);
1816 if ((u64
)unmap_end
> (u64
)unmap_start
)
1817 unmap_mapping_range(mapping
, unmap_start
,
1818 1 + unmap_end
- unmap_start
, 0);
1819 shmem_truncate_range(inode
, offset
, offset
+ len
- 1);
1820 /* No need to unmap again: hole-punching leaves COWed pages */
1822 spin_lock(&inode
->i_lock
);
1823 inode
->i_private
= NULL
;
1824 wake_up_all(&shmem_falloc_waitq
);
1825 spin_unlock(&inode
->i_lock
);
1830 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1831 error
= inode_newsize_ok(inode
, offset
+ len
);
1835 start
= offset
>> PAGE_CACHE_SHIFT
;
1836 end
= (offset
+ len
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1837 /* Try to avoid a swapstorm if len is impossible to satisfy */
1838 if (sbinfo
->max_blocks
&& end
- start
> sbinfo
->max_blocks
) {
1843 shmem_falloc
.waitq
= NULL
;
1844 shmem_falloc
.start
= start
;
1845 shmem_falloc
.next
= start
;
1846 shmem_falloc
.nr_falloced
= 0;
1847 shmem_falloc
.nr_unswapped
= 0;
1848 spin_lock(&inode
->i_lock
);
1849 inode
->i_private
= &shmem_falloc
;
1850 spin_unlock(&inode
->i_lock
);
1852 for (index
= start
; index
< end
; index
++) {
1856 * Good, the fallocate(2) manpage permits EINTR: we may have
1857 * been interrupted because we are using up too much memory.
1859 if (signal_pending(current
))
1861 else if (shmem_falloc
.nr_unswapped
> shmem_falloc
.nr_falloced
)
1864 error
= shmem_getpage(inode
, index
, &page
, SGP_FALLOC
,
1867 /* Remove the !PageUptodate pages we added */
1868 shmem_undo_range(inode
,
1869 (loff_t
)start
<< PAGE_CACHE_SHIFT
,
1870 (loff_t
)index
<< PAGE_CACHE_SHIFT
, true);
1875 * Inform shmem_writepage() how far we have reached.
1876 * No need for lock or barrier: we have the page lock.
1878 shmem_falloc
.next
++;
1879 if (!PageUptodate(page
))
1880 shmem_falloc
.nr_falloced
++;
1883 * If !PageUptodate, leave it that way so that freeable pages
1884 * can be recognized if we need to rollback on error later.
1885 * But set_page_dirty so that memory pressure will swap rather
1886 * than free the pages we are allocating (and SGP_CACHE pages
1887 * might still be clean: we now need to mark those dirty too).
1889 set_page_dirty(page
);
1891 page_cache_release(page
);
1895 if (!(mode
& FALLOC_FL_KEEP_SIZE
) && offset
+ len
> inode
->i_size
)
1896 i_size_write(inode
, offset
+ len
);
1897 inode
->i_ctime
= CURRENT_TIME
;
1899 spin_lock(&inode
->i_lock
);
1900 inode
->i_private
= NULL
;
1901 spin_unlock(&inode
->i_lock
);
1903 mutex_unlock(&inode
->i_mutex
);
1907 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1909 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1911 buf
->f_type
= TMPFS_MAGIC
;
1912 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1913 buf
->f_namelen
= NAME_MAX
;
1914 if (sbinfo
->max_blocks
) {
1915 buf
->f_blocks
= sbinfo
->max_blocks
;
1917 buf
->f_bfree
= sbinfo
->max_blocks
-
1918 percpu_counter_sum(&sbinfo
->used_blocks
);
1920 if (sbinfo
->max_inodes
) {
1921 buf
->f_files
= sbinfo
->max_inodes
;
1922 buf
->f_ffree
= sbinfo
->free_inodes
;
1924 /* else leave those fields 0 like simple_statfs */
1929 * File creation. Allocate an inode, and we're done..
1932 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
1934 struct inode
*inode
;
1935 int error
= -ENOSPC
;
1937 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, dev
, VM_NORESERVE
);
1939 error
= simple_acl_create(dir
, inode
);
1942 error
= security_inode_init_security(inode
, dir
,
1944 shmem_initxattrs
, NULL
);
1945 if (error
&& error
!= -EOPNOTSUPP
)
1949 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1950 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1951 d_instantiate(dentry
, inode
);
1952 dget(dentry
); /* Extra count - pin the dentry in core */
1961 shmem_tmpfile(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
1963 struct inode
*inode
;
1964 int error
= -ENOSPC
;
1966 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, 0, VM_NORESERVE
);
1968 error
= security_inode_init_security(inode
, dir
,
1970 shmem_initxattrs
, NULL
);
1971 if (error
&& error
!= -EOPNOTSUPP
)
1973 error
= simple_acl_create(dir
, inode
);
1976 d_tmpfile(dentry
, inode
);
1984 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
1988 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1994 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
1997 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
2003 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
2005 struct inode
*inode
= old_dentry
->d_inode
;
2009 * No ordinary (disk based) filesystem counts links as inodes;
2010 * but each new link needs a new dentry, pinning lowmem, and
2011 * tmpfs dentries cannot be pruned until they are unlinked.
2013 ret
= shmem_reserve_inode(inode
->i_sb
);
2017 dir
->i_size
+= BOGO_DIRENT_SIZE
;
2018 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2020 ihold(inode
); /* New dentry reference */
2021 dget(dentry
); /* Extra pinning count for the created dentry */
2022 d_instantiate(dentry
, inode
);
2027 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
2029 struct inode
*inode
= dentry
->d_inode
;
2031 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
2032 shmem_free_inode(inode
->i_sb
);
2034 dir
->i_size
-= BOGO_DIRENT_SIZE
;
2035 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2037 dput(dentry
); /* Undo the count from "create" - this does all the work */
2041 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2043 if (!simple_empty(dentry
))
2046 drop_nlink(dentry
->d_inode
);
2048 return shmem_unlink(dir
, dentry
);
2052 * The VFS layer already does all the dentry stuff for rename,
2053 * we just have to decrement the usage count for the target if
2054 * it exists so that the VFS layer correctly free's it when it
2057 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
2059 struct inode
*inode
= old_dentry
->d_inode
;
2060 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
2062 if (!simple_empty(new_dentry
))
2065 if (new_dentry
->d_inode
) {
2066 (void) shmem_unlink(new_dir
, new_dentry
);
2068 drop_nlink(old_dir
);
2069 } else if (they_are_dirs
) {
2070 drop_nlink(old_dir
);
2074 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
2075 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
2076 old_dir
->i_ctime
= old_dir
->i_mtime
=
2077 new_dir
->i_ctime
= new_dir
->i_mtime
=
2078 inode
->i_ctime
= CURRENT_TIME
;
2082 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
2086 struct inode
*inode
;
2089 struct shmem_inode_info
*info
;
2091 len
= strlen(symname
) + 1;
2092 if (len
> PAGE_CACHE_SIZE
)
2093 return -ENAMETOOLONG
;
2095 inode
= shmem_get_inode(dir
->i_sb
, dir
, S_IFLNK
|S_IRWXUGO
, 0, VM_NORESERVE
);
2099 error
= security_inode_init_security(inode
, dir
, &dentry
->d_name
,
2100 shmem_initxattrs
, NULL
);
2102 if (error
!= -EOPNOTSUPP
) {
2109 info
= SHMEM_I(inode
);
2110 inode
->i_size
= len
-1;
2111 if (len
<= SHORT_SYMLINK_LEN
) {
2112 info
->symlink
= kmemdup(symname
, len
, GFP_KERNEL
);
2113 if (!info
->symlink
) {
2117 inode
->i_op
= &shmem_short_symlink_operations
;
2119 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
2124 inode
->i_mapping
->a_ops
= &shmem_aops
;
2125 inode
->i_op
= &shmem_symlink_inode_operations
;
2126 kaddr
= kmap_atomic(page
);
2127 memcpy(kaddr
, symname
, len
);
2128 kunmap_atomic(kaddr
);
2129 SetPageUptodate(page
);
2130 set_page_dirty(page
);
2132 page_cache_release(page
);
2134 dir
->i_size
+= BOGO_DIRENT_SIZE
;
2135 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2136 d_instantiate(dentry
, inode
);
2141 static void *shmem_follow_short_symlink(struct dentry
*dentry
, struct nameidata
*nd
)
2143 nd_set_link(nd
, SHMEM_I(dentry
->d_inode
)->symlink
);
2147 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
2149 struct page
*page
= NULL
;
2150 int error
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
2151 nd_set_link(nd
, error
? ERR_PTR(error
) : kmap(page
));
2157 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2159 if (!IS_ERR(nd_get_link(nd
))) {
2160 struct page
*page
= cookie
;
2162 mark_page_accessed(page
);
2163 page_cache_release(page
);
2167 #ifdef CONFIG_TMPFS_XATTR
2169 * Superblocks without xattr inode operations may get some security.* xattr
2170 * support from the LSM "for free". As soon as we have any other xattrs
2171 * like ACLs, we also need to implement the security.* handlers at
2172 * filesystem level, though.
2176 * Callback for security_inode_init_security() for acquiring xattrs.
2178 static int shmem_initxattrs(struct inode
*inode
,
2179 const struct xattr
*xattr_array
,
2182 struct shmem_inode_info
*info
= SHMEM_I(inode
);
2183 const struct xattr
*xattr
;
2184 struct simple_xattr
*new_xattr
;
2187 for (xattr
= xattr_array
; xattr
->name
!= NULL
; xattr
++) {
2188 new_xattr
= simple_xattr_alloc(xattr
->value
, xattr
->value_len
);
2192 len
= strlen(xattr
->name
) + 1;
2193 new_xattr
->name
= kmalloc(XATTR_SECURITY_PREFIX_LEN
+ len
,
2195 if (!new_xattr
->name
) {
2200 memcpy(new_xattr
->name
, XATTR_SECURITY_PREFIX
,
2201 XATTR_SECURITY_PREFIX_LEN
);
2202 memcpy(new_xattr
->name
+ XATTR_SECURITY_PREFIX_LEN
,
2205 simple_xattr_list_add(&info
->xattrs
, new_xattr
);
2211 static const struct xattr_handler
*shmem_xattr_handlers
[] = {
2212 #ifdef CONFIG_TMPFS_POSIX_ACL
2213 &posix_acl_access_xattr_handler
,
2214 &posix_acl_default_xattr_handler
,
2219 static int shmem_xattr_validate(const char *name
)
2221 struct { const char *prefix
; size_t len
; } arr
[] = {
2222 { XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
},
2223 { XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
}
2227 for (i
= 0; i
< ARRAY_SIZE(arr
); i
++) {
2228 size_t preflen
= arr
[i
].len
;
2229 if (strncmp(name
, arr
[i
].prefix
, preflen
) == 0) {
2238 static ssize_t
shmem_getxattr(struct dentry
*dentry
, const char *name
,
2239 void *buffer
, size_t size
)
2241 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2245 * If this is a request for a synthetic attribute in the system.*
2246 * namespace use the generic infrastructure to resolve a handler
2247 * for it via sb->s_xattr.
2249 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2250 return generic_getxattr(dentry
, name
, buffer
, size
);
2252 err
= shmem_xattr_validate(name
);
2256 return simple_xattr_get(&info
->xattrs
, name
, buffer
, size
);
2259 static int shmem_setxattr(struct dentry
*dentry
, const char *name
,
2260 const void *value
, size_t size
, int flags
)
2262 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2266 * If this is a request for a synthetic attribute in the system.*
2267 * namespace use the generic infrastructure to resolve a handler
2268 * for it via sb->s_xattr.
2270 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2271 return generic_setxattr(dentry
, name
, value
, size
, flags
);
2273 err
= shmem_xattr_validate(name
);
2277 return simple_xattr_set(&info
->xattrs
, name
, value
, size
, flags
);
2280 static int shmem_removexattr(struct dentry
*dentry
, const char *name
)
2282 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2286 * If this is a request for a synthetic attribute in the system.*
2287 * namespace use the generic infrastructure to resolve a handler
2288 * for it via sb->s_xattr.
2290 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2291 return generic_removexattr(dentry
, name
);
2293 err
= shmem_xattr_validate(name
);
2297 return simple_xattr_remove(&info
->xattrs
, name
);
2300 static ssize_t
shmem_listxattr(struct dentry
*dentry
, char *buffer
, size_t size
)
2302 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2303 return simple_xattr_list(&info
->xattrs
, buffer
, size
);
2305 #endif /* CONFIG_TMPFS_XATTR */
2307 static const struct inode_operations shmem_short_symlink_operations
= {
2308 .readlink
= generic_readlink
,
2309 .follow_link
= shmem_follow_short_symlink
,
2310 #ifdef CONFIG_TMPFS_XATTR
2311 .setxattr
= shmem_setxattr
,
2312 .getxattr
= shmem_getxattr
,
2313 .listxattr
= shmem_listxattr
,
2314 .removexattr
= shmem_removexattr
,
2318 static const struct inode_operations shmem_symlink_inode_operations
= {
2319 .readlink
= generic_readlink
,
2320 .follow_link
= shmem_follow_link
,
2321 .put_link
= shmem_put_link
,
2322 #ifdef CONFIG_TMPFS_XATTR
2323 .setxattr
= shmem_setxattr
,
2324 .getxattr
= shmem_getxattr
,
2325 .listxattr
= shmem_listxattr
,
2326 .removexattr
= shmem_removexattr
,
2330 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2332 return ERR_PTR(-ESTALE
);
2335 static int shmem_match(struct inode
*ino
, void *vfh
)
2339 inum
= (inum
<< 32) | fh
[1];
2340 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2343 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
2344 struct fid
*fid
, int fh_len
, int fh_type
)
2346 struct inode
*inode
;
2347 struct dentry
*dentry
= NULL
;
2354 inum
= (inum
<< 32) | fid
->raw
[1];
2356 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
2357 shmem_match
, fid
->raw
);
2359 dentry
= d_find_alias(inode
);
2366 static int shmem_encode_fh(struct inode
*inode
, __u32
*fh
, int *len
,
2367 struct inode
*parent
)
2371 return FILEID_INVALID
;
2374 if (inode_unhashed(inode
)) {
2375 /* Unfortunately insert_inode_hash is not idempotent,
2376 * so as we hash inodes here rather than at creation
2377 * time, we need a lock to ensure we only try
2380 static DEFINE_SPINLOCK(lock
);
2382 if (inode_unhashed(inode
))
2383 __insert_inode_hash(inode
,
2384 inode
->i_ino
+ inode
->i_generation
);
2388 fh
[0] = inode
->i_generation
;
2389 fh
[1] = inode
->i_ino
;
2390 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2396 static const struct export_operations shmem_export_ops
= {
2397 .get_parent
= shmem_get_parent
,
2398 .encode_fh
= shmem_encode_fh
,
2399 .fh_to_dentry
= shmem_fh_to_dentry
,
2402 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2405 char *this_char
, *value
, *rest
;
2406 struct mempolicy
*mpol
= NULL
;
2410 while (options
!= NULL
) {
2411 this_char
= options
;
2414 * NUL-terminate this option: unfortunately,
2415 * mount options form a comma-separated list,
2416 * but mpol's nodelist may also contain commas.
2418 options
= strchr(options
, ',');
2419 if (options
== NULL
)
2422 if (!isdigit(*options
)) {
2429 if ((value
= strchr(this_char
,'=')) != NULL
) {
2433 "tmpfs: No value for mount option '%s'\n",
2438 if (!strcmp(this_char
,"size")) {
2439 unsigned long long size
;
2440 size
= memparse(value
,&rest
);
2442 size
<<= PAGE_SHIFT
;
2443 size
*= totalram_pages
;
2449 sbinfo
->max_blocks
=
2450 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2451 } else if (!strcmp(this_char
,"nr_blocks")) {
2452 sbinfo
->max_blocks
= memparse(value
, &rest
);
2455 } else if (!strcmp(this_char
,"nr_inodes")) {
2456 sbinfo
->max_inodes
= memparse(value
, &rest
);
2459 } else if (!strcmp(this_char
,"mode")) {
2462 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2465 } else if (!strcmp(this_char
,"uid")) {
2468 uid
= simple_strtoul(value
, &rest
, 0);
2471 sbinfo
->uid
= make_kuid(current_user_ns(), uid
);
2472 if (!uid_valid(sbinfo
->uid
))
2474 } else if (!strcmp(this_char
,"gid")) {
2477 gid
= simple_strtoul(value
, &rest
, 0);
2480 sbinfo
->gid
= make_kgid(current_user_ns(), gid
);
2481 if (!gid_valid(sbinfo
->gid
))
2483 } else if (!strcmp(this_char
,"mpol")) {
2486 if (mpol_parse_str(value
, &mpol
))
2489 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2494 sbinfo
->mpol
= mpol
;
2498 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2506 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2508 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2509 struct shmem_sb_info config
= *sbinfo
;
2510 unsigned long inodes
;
2511 int error
= -EINVAL
;
2514 if (shmem_parse_options(data
, &config
, true))
2517 spin_lock(&sbinfo
->stat_lock
);
2518 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2519 if (percpu_counter_compare(&sbinfo
->used_blocks
, config
.max_blocks
) > 0)
2521 if (config
.max_inodes
< inodes
)
2524 * Those tests disallow limited->unlimited while any are in use;
2525 * but we must separately disallow unlimited->limited, because
2526 * in that case we have no record of how much is already in use.
2528 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2530 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2534 sbinfo
->max_blocks
= config
.max_blocks
;
2535 sbinfo
->max_inodes
= config
.max_inodes
;
2536 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2539 * Preserve previous mempolicy unless mpol remount option was specified.
2542 mpol_put(sbinfo
->mpol
);
2543 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2546 spin_unlock(&sbinfo
->stat_lock
);
2550 static int shmem_show_options(struct seq_file
*seq
, struct dentry
*root
)
2552 struct shmem_sb_info
*sbinfo
= SHMEM_SB(root
->d_sb
);
2554 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2555 seq_printf(seq
, ",size=%luk",
2556 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2557 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2558 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2559 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2560 seq_printf(seq
, ",mode=%03ho", sbinfo
->mode
);
2561 if (!uid_eq(sbinfo
->uid
, GLOBAL_ROOT_UID
))
2562 seq_printf(seq
, ",uid=%u",
2563 from_kuid_munged(&init_user_ns
, sbinfo
->uid
));
2564 if (!gid_eq(sbinfo
->gid
, GLOBAL_ROOT_GID
))
2565 seq_printf(seq
, ",gid=%u",
2566 from_kgid_munged(&init_user_ns
, sbinfo
->gid
));
2567 shmem_show_mpol(seq
, sbinfo
->mpol
);
2570 #endif /* CONFIG_TMPFS */
2572 static void shmem_put_super(struct super_block
*sb
)
2574 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2576 percpu_counter_destroy(&sbinfo
->used_blocks
);
2577 mpol_put(sbinfo
->mpol
);
2579 sb
->s_fs_info
= NULL
;
2582 int shmem_fill_super(struct super_block
*sb
, void *data
, int silent
)
2584 struct inode
*inode
;
2585 struct shmem_sb_info
*sbinfo
;
2588 /* Round up to L1_CACHE_BYTES to resist false sharing */
2589 sbinfo
= kzalloc(max((int)sizeof(struct shmem_sb_info
),
2590 L1_CACHE_BYTES
), GFP_KERNEL
);
2594 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2595 sbinfo
->uid
= current_fsuid();
2596 sbinfo
->gid
= current_fsgid();
2597 sb
->s_fs_info
= sbinfo
;
2601 * Per default we only allow half of the physical ram per
2602 * tmpfs instance, limiting inodes to one per page of lowmem;
2603 * but the internal instance is left unlimited.
2605 if (!(sb
->s_flags
& MS_KERNMOUNT
)) {
2606 sbinfo
->max_blocks
= shmem_default_max_blocks();
2607 sbinfo
->max_inodes
= shmem_default_max_inodes();
2608 if (shmem_parse_options(data
, sbinfo
, false)) {
2613 sb
->s_flags
|= MS_NOUSER
;
2615 sb
->s_export_op
= &shmem_export_ops
;
2616 sb
->s_flags
|= MS_NOSEC
;
2618 sb
->s_flags
|= MS_NOUSER
;
2621 spin_lock_init(&sbinfo
->stat_lock
);
2622 if (percpu_counter_init(&sbinfo
->used_blocks
, 0))
2624 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2626 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
2627 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2628 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2629 sb
->s_magic
= TMPFS_MAGIC
;
2630 sb
->s_op
= &shmem_ops
;
2631 sb
->s_time_gran
= 1;
2632 #ifdef CONFIG_TMPFS_XATTR
2633 sb
->s_xattr
= shmem_xattr_handlers
;
2635 #ifdef CONFIG_TMPFS_POSIX_ACL
2636 sb
->s_flags
|= MS_POSIXACL
;
2639 inode
= shmem_get_inode(sb
, NULL
, S_IFDIR
| sbinfo
->mode
, 0, VM_NORESERVE
);
2642 inode
->i_uid
= sbinfo
->uid
;
2643 inode
->i_gid
= sbinfo
->gid
;
2644 sb
->s_root
= d_make_root(inode
);
2650 shmem_put_super(sb
);
2654 static struct kmem_cache
*shmem_inode_cachep
;
2656 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2658 struct shmem_inode_info
*info
;
2659 info
= kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2662 return &info
->vfs_inode
;
2665 static void shmem_destroy_callback(struct rcu_head
*head
)
2667 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
2668 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2671 static void shmem_destroy_inode(struct inode
*inode
)
2673 if (S_ISREG(inode
->i_mode
))
2674 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2675 call_rcu(&inode
->i_rcu
, shmem_destroy_callback
);
2678 static void shmem_init_inode(void *foo
)
2680 struct shmem_inode_info
*info
= foo
;
2681 inode_init_once(&info
->vfs_inode
);
2684 static int shmem_init_inodecache(void)
2686 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2687 sizeof(struct shmem_inode_info
),
2688 0, SLAB_PANIC
, shmem_init_inode
);
2692 static void shmem_destroy_inodecache(void)
2694 kmem_cache_destroy(shmem_inode_cachep
);
2697 static const struct address_space_operations shmem_aops
= {
2698 .writepage
= shmem_writepage
,
2699 .set_page_dirty
= __set_page_dirty_no_writeback
,
2701 .write_begin
= shmem_write_begin
,
2702 .write_end
= shmem_write_end
,
2704 .migratepage
= migrate_page
,
2705 .error_remove_page
= generic_error_remove_page
,
2708 static const struct file_operations shmem_file_operations
= {
2711 .llseek
= shmem_file_llseek
,
2712 .read
= new_sync_read
,
2713 .write
= new_sync_write
,
2714 .read_iter
= shmem_file_read_iter
,
2715 .write_iter
= generic_file_write_iter
,
2716 .fsync
= noop_fsync
,
2717 .splice_read
= shmem_file_splice_read
,
2718 .splice_write
= iter_file_splice_write
,
2719 .fallocate
= shmem_fallocate
,
2723 static const struct inode_operations shmem_inode_operations
= {
2724 .setattr
= shmem_setattr
,
2725 #ifdef CONFIG_TMPFS_XATTR
2726 .setxattr
= shmem_setxattr
,
2727 .getxattr
= shmem_getxattr
,
2728 .listxattr
= shmem_listxattr
,
2729 .removexattr
= shmem_removexattr
,
2730 .set_acl
= simple_set_acl
,
2734 static const struct inode_operations shmem_dir_inode_operations
= {
2736 .create
= shmem_create
,
2737 .lookup
= simple_lookup
,
2739 .unlink
= shmem_unlink
,
2740 .symlink
= shmem_symlink
,
2741 .mkdir
= shmem_mkdir
,
2742 .rmdir
= shmem_rmdir
,
2743 .mknod
= shmem_mknod
,
2744 .rename
= shmem_rename
,
2745 .tmpfile
= shmem_tmpfile
,
2747 #ifdef CONFIG_TMPFS_XATTR
2748 .setxattr
= shmem_setxattr
,
2749 .getxattr
= shmem_getxattr
,
2750 .listxattr
= shmem_listxattr
,
2751 .removexattr
= shmem_removexattr
,
2753 #ifdef CONFIG_TMPFS_POSIX_ACL
2754 .setattr
= shmem_setattr
,
2755 .set_acl
= simple_set_acl
,
2759 static const struct inode_operations shmem_special_inode_operations
= {
2760 #ifdef CONFIG_TMPFS_XATTR
2761 .setxattr
= shmem_setxattr
,
2762 .getxattr
= shmem_getxattr
,
2763 .listxattr
= shmem_listxattr
,
2764 .removexattr
= shmem_removexattr
,
2766 #ifdef CONFIG_TMPFS_POSIX_ACL
2767 .setattr
= shmem_setattr
,
2768 .set_acl
= simple_set_acl
,
2772 static const struct super_operations shmem_ops
= {
2773 .alloc_inode
= shmem_alloc_inode
,
2774 .destroy_inode
= shmem_destroy_inode
,
2776 .statfs
= shmem_statfs
,
2777 .remount_fs
= shmem_remount_fs
,
2778 .show_options
= shmem_show_options
,
2780 .evict_inode
= shmem_evict_inode
,
2781 .drop_inode
= generic_delete_inode
,
2782 .put_super
= shmem_put_super
,
2785 static const struct vm_operations_struct shmem_vm_ops
= {
2786 .fault
= shmem_fault
,
2787 .map_pages
= filemap_map_pages
,
2789 .set_policy
= shmem_set_policy
,
2790 .get_policy
= shmem_get_policy
,
2792 .remap_pages
= generic_file_remap_pages
,
2795 static struct dentry
*shmem_mount(struct file_system_type
*fs_type
,
2796 int flags
, const char *dev_name
, void *data
)
2798 return mount_nodev(fs_type
, flags
, data
, shmem_fill_super
);
2801 static struct file_system_type shmem_fs_type
= {
2802 .owner
= THIS_MODULE
,
2804 .mount
= shmem_mount
,
2805 .kill_sb
= kill_litter_super
,
2806 .fs_flags
= FS_USERNS_MOUNT
,
2809 int __init
shmem_init(void)
2813 /* If rootfs called this, don't re-init */
2814 if (shmem_inode_cachep
)
2817 error
= bdi_init(&shmem_backing_dev_info
);
2821 error
= shmem_init_inodecache();
2825 error
= register_filesystem(&shmem_fs_type
);
2827 printk(KERN_ERR
"Could not register tmpfs\n");
2831 shm_mnt
= kern_mount(&shmem_fs_type
);
2832 if (IS_ERR(shm_mnt
)) {
2833 error
= PTR_ERR(shm_mnt
);
2834 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2840 unregister_filesystem(&shmem_fs_type
);
2842 shmem_destroy_inodecache();
2844 bdi_destroy(&shmem_backing_dev_info
);
2846 shm_mnt
= ERR_PTR(error
);
2850 #else /* !CONFIG_SHMEM */
2853 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2855 * This is intended for small system where the benefits of the full
2856 * shmem code (swap-backed and resource-limited) are outweighed by
2857 * their complexity. On systems without swap this code should be
2858 * effectively equivalent, but much lighter weight.
2861 static struct file_system_type shmem_fs_type
= {
2863 .mount
= ramfs_mount
,
2864 .kill_sb
= kill_litter_super
,
2865 .fs_flags
= FS_USERNS_MOUNT
,
2868 int __init
shmem_init(void)
2870 BUG_ON(register_filesystem(&shmem_fs_type
) != 0);
2872 shm_mnt
= kern_mount(&shmem_fs_type
);
2873 BUG_ON(IS_ERR(shm_mnt
));
2878 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
2883 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
2888 void shmem_unlock_mapping(struct address_space
*mapping
)
2892 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
2894 truncate_inode_pages_range(inode
->i_mapping
, lstart
, lend
);
2896 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
2898 #define shmem_vm_ops generic_file_vm_ops
2899 #define shmem_file_operations ramfs_file_operations
2900 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2901 #define shmem_acct_size(flags, size) 0
2902 #define shmem_unacct_size(flags, size) do {} while (0)
2904 #endif /* CONFIG_SHMEM */
2908 static struct dentry_operations anon_ops
= {
2909 .d_dname
= simple_dname
2912 static struct file
*__shmem_file_setup(const char *name
, loff_t size
,
2913 unsigned long flags
, unsigned int i_flags
)
2916 struct inode
*inode
;
2918 struct super_block
*sb
;
2921 if (IS_ERR(shm_mnt
))
2922 return ERR_CAST(shm_mnt
);
2924 if (size
< 0 || size
> MAX_LFS_FILESIZE
)
2925 return ERR_PTR(-EINVAL
);
2927 if (shmem_acct_size(flags
, size
))
2928 return ERR_PTR(-ENOMEM
);
2930 res
= ERR_PTR(-ENOMEM
);
2932 this.len
= strlen(name
);
2933 this.hash
= 0; /* will go */
2934 sb
= shm_mnt
->mnt_sb
;
2935 path
.dentry
= d_alloc_pseudo(sb
, &this);
2938 d_set_d_op(path
.dentry
, &anon_ops
);
2939 path
.mnt
= mntget(shm_mnt
);
2941 res
= ERR_PTR(-ENOSPC
);
2942 inode
= shmem_get_inode(sb
, NULL
, S_IFREG
| S_IRWXUGO
, 0, flags
);
2946 inode
->i_flags
|= i_flags
;
2947 d_instantiate(path
.dentry
, inode
);
2948 inode
->i_size
= size
;
2949 clear_nlink(inode
); /* It is unlinked */
2950 res
= ERR_PTR(ramfs_nommu_expand_for_mapping(inode
, size
));
2954 res
= alloc_file(&path
, FMODE_WRITE
| FMODE_READ
,
2955 &shmem_file_operations
);
2964 shmem_unacct_size(flags
, size
);
2969 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
2970 * kernel internal. There will be NO LSM permission checks against the
2971 * underlying inode. So users of this interface must do LSM checks at a
2972 * higher layer. The one user is the big_key implementation. LSM checks
2973 * are provided at the key level rather than the inode level.
2974 * @name: name for dentry (to be seen in /proc/<pid>/maps
2975 * @size: size to be set for the file
2976 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2978 struct file
*shmem_kernel_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2980 return __shmem_file_setup(name
, size
, flags
, S_PRIVATE
);
2984 * shmem_file_setup - get an unlinked file living in tmpfs
2985 * @name: name for dentry (to be seen in /proc/<pid>/maps
2986 * @size: size to be set for the file
2987 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2989 struct file
*shmem_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2991 return __shmem_file_setup(name
, size
, flags
, 0);
2993 EXPORT_SYMBOL_GPL(shmem_file_setup
);
2996 * shmem_zero_setup - setup a shared anonymous mapping
2997 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2999 int shmem_zero_setup(struct vm_area_struct
*vma
)
3002 loff_t size
= vma
->vm_end
- vma
->vm_start
;
3004 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
3006 return PTR_ERR(file
);
3010 vma
->vm_file
= file
;
3011 vma
->vm_ops
= &shmem_vm_ops
;
3016 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
3017 * @mapping: the page's address_space
3018 * @index: the page index
3019 * @gfp: the page allocator flags to use if allocating
3021 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
3022 * with any new page allocations done using the specified allocation flags.
3023 * But read_cache_page_gfp() uses the ->readpage() method: which does not
3024 * suit tmpfs, since it may have pages in swapcache, and needs to find those
3025 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
3027 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
3028 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
3030 struct page
*shmem_read_mapping_page_gfp(struct address_space
*mapping
,
3031 pgoff_t index
, gfp_t gfp
)
3034 struct inode
*inode
= mapping
->host
;
3038 BUG_ON(mapping
->a_ops
!= &shmem_aops
);
3039 error
= shmem_getpage_gfp(inode
, index
, &page
, SGP_CACHE
, gfp
, NULL
);
3041 page
= ERR_PTR(error
);
3047 * The tiny !SHMEM case uses ramfs without swap
3049 return read_cache_page_gfp(mapping
, index
, gfp
);
3052 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp
);