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 int mode
; /* FALLOC_FL mode currently operating */
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
);
474 pvec
.nr
= find_get_entries(mapping
, index
,
475 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
),
476 pvec
.pages
, indices
);
478 if (index
== start
|| unfalloc
)
483 if ((index
== start
|| unfalloc
) && indices
[0] >= end
) {
484 pagevec_remove_exceptionals(&pvec
);
485 pagevec_release(&pvec
);
488 mem_cgroup_uncharge_start();
489 for (i
= 0; i
< pagevec_count(&pvec
); i
++) {
490 struct page
*page
= pvec
.pages
[i
];
496 if (radix_tree_exceptional_entry(page
)) {
499 nr_swaps_freed
+= !shmem_free_swap(mapping
,
505 if (!unfalloc
|| !PageUptodate(page
)) {
506 if (page
->mapping
== mapping
) {
507 VM_BUG_ON_PAGE(PageWriteback(page
), page
);
508 truncate_inode_page(mapping
, page
);
513 pagevec_remove_exceptionals(&pvec
);
514 pagevec_release(&pvec
);
515 mem_cgroup_uncharge_end();
519 spin_lock(&info
->lock
);
520 info
->swapped
-= nr_swaps_freed
;
521 shmem_recalc_inode(inode
);
522 spin_unlock(&info
->lock
);
525 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
527 shmem_undo_range(inode
, lstart
, lend
, false);
528 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
530 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
532 static int shmem_setattr(struct dentry
*dentry
, struct iattr
*attr
)
534 struct inode
*inode
= dentry
->d_inode
;
537 error
= inode_change_ok(inode
, attr
);
541 if (S_ISREG(inode
->i_mode
) && (attr
->ia_valid
& ATTR_SIZE
)) {
542 loff_t oldsize
= inode
->i_size
;
543 loff_t newsize
= attr
->ia_size
;
545 if (newsize
!= oldsize
) {
546 i_size_write(inode
, newsize
);
547 inode
->i_ctime
= inode
->i_mtime
= CURRENT_TIME
;
549 if (newsize
< oldsize
) {
550 loff_t holebegin
= round_up(newsize
, PAGE_SIZE
);
551 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
552 shmem_truncate_range(inode
, newsize
, (loff_t
)-1);
553 /* unmap again to remove racily COWed private pages */
554 unmap_mapping_range(inode
->i_mapping
, holebegin
, 0, 1);
558 setattr_copy(inode
, attr
);
559 if (attr
->ia_valid
& ATTR_MODE
)
560 error
= posix_acl_chmod(inode
, inode
->i_mode
);
564 static void shmem_evict_inode(struct inode
*inode
)
566 struct shmem_inode_info
*info
= SHMEM_I(inode
);
568 if (inode
->i_mapping
->a_ops
== &shmem_aops
) {
569 shmem_unacct_size(info
->flags
, inode
->i_size
);
571 shmem_truncate_range(inode
, 0, (loff_t
)-1);
572 if (!list_empty(&info
->swaplist
)) {
573 mutex_lock(&shmem_swaplist_mutex
);
574 list_del_init(&info
->swaplist
);
575 mutex_unlock(&shmem_swaplist_mutex
);
578 kfree(info
->symlink
);
580 simple_xattrs_free(&info
->xattrs
);
581 WARN_ON(inode
->i_blocks
);
582 shmem_free_inode(inode
->i_sb
);
587 * If swap found in inode, free it and move page from swapcache to filecache.
589 static int shmem_unuse_inode(struct shmem_inode_info
*info
,
590 swp_entry_t swap
, struct page
**pagep
)
592 struct address_space
*mapping
= info
->vfs_inode
.i_mapping
;
598 radswap
= swp_to_radix_entry(swap
);
599 index
= radix_tree_locate_item(&mapping
->page_tree
, radswap
);
604 * Move _head_ to start search for next from here.
605 * But be careful: shmem_evict_inode checks list_empty without taking
606 * mutex, and there's an instant in list_move_tail when info->swaplist
607 * would appear empty, if it were the only one on shmem_swaplist.
609 if (shmem_swaplist
.next
!= &info
->swaplist
)
610 list_move_tail(&shmem_swaplist
, &info
->swaplist
);
612 gfp
= mapping_gfp_mask(mapping
);
613 if (shmem_should_replace_page(*pagep
, gfp
)) {
614 mutex_unlock(&shmem_swaplist_mutex
);
615 error
= shmem_replace_page(pagep
, gfp
, info
, index
);
616 mutex_lock(&shmem_swaplist_mutex
);
618 * We needed to drop mutex to make that restrictive page
619 * allocation, but the inode might have been freed while we
620 * dropped it: although a racing shmem_evict_inode() cannot
621 * complete without emptying the radix_tree, our page lock
622 * on this swapcache page is not enough to prevent that -
623 * free_swap_and_cache() of our swap entry will only
624 * trylock_page(), removing swap from radix_tree whatever.
626 * We must not proceed to shmem_add_to_page_cache() if the
627 * inode has been freed, but of course we cannot rely on
628 * inode or mapping or info to check that. However, we can
629 * safely check if our swap entry is still in use (and here
630 * it can't have got reused for another page): if it's still
631 * in use, then the inode cannot have been freed yet, and we
632 * can safely proceed (if it's no longer in use, that tells
633 * nothing about the inode, but we don't need to unuse swap).
635 if (!page_swapcount(*pagep
))
640 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
641 * but also to hold up shmem_evict_inode(): so inode cannot be freed
642 * beneath us (pagelock doesn't help until the page is in pagecache).
645 error
= shmem_add_to_page_cache(*pagep
, mapping
, index
,
646 GFP_NOWAIT
, radswap
);
647 if (error
!= -ENOMEM
) {
649 * Truncation and eviction use free_swap_and_cache(), which
650 * only does trylock page: if we raced, best clean up here.
652 delete_from_swap_cache(*pagep
);
653 set_page_dirty(*pagep
);
655 spin_lock(&info
->lock
);
657 spin_unlock(&info
->lock
);
660 error
= 1; /* not an error, but entry was found */
666 * Search through swapped inodes to find and replace swap by page.
668 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
670 struct list_head
*this, *next
;
671 struct shmem_inode_info
*info
;
676 * There's a faint possibility that swap page was replaced before
677 * caller locked it: caller will come back later with the right page.
679 if (unlikely(!PageSwapCache(page
) || page_private(page
) != swap
.val
))
683 * Charge page using GFP_KERNEL while we can wait, before taking
684 * the shmem_swaplist_mutex which might hold up shmem_writepage().
685 * Charged back to the user (not to caller) when swap account is used.
687 error
= mem_cgroup_charge_file(page
, current
->mm
, GFP_KERNEL
);
690 /* No radix_tree_preload: swap entry keeps a place for page in tree */
692 mutex_lock(&shmem_swaplist_mutex
);
693 list_for_each_safe(this, next
, &shmem_swaplist
) {
694 info
= list_entry(this, struct shmem_inode_info
, swaplist
);
696 found
= shmem_unuse_inode(info
, swap
, &page
);
698 list_del_init(&info
->swaplist
);
703 mutex_unlock(&shmem_swaplist_mutex
);
709 page_cache_release(page
);
714 * Move the page from the page cache to the swap cache.
716 static int shmem_writepage(struct page
*page
, struct writeback_control
*wbc
)
718 struct shmem_inode_info
*info
;
719 struct address_space
*mapping
;
724 BUG_ON(!PageLocked(page
));
725 mapping
= page
->mapping
;
727 inode
= mapping
->host
;
728 info
= SHMEM_I(inode
);
729 if (info
->flags
& VM_LOCKED
)
731 if (!total_swap_pages
)
735 * shmem_backing_dev_info's capabilities prevent regular writeback or
736 * sync from ever calling shmem_writepage; but a stacking filesystem
737 * might use ->writepage of its underlying filesystem, in which case
738 * tmpfs should write out to swap only in response to memory pressure,
739 * and not for the writeback threads or sync.
741 if (!wbc
->for_reclaim
) {
742 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
747 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
748 * value into swapfile.c, the only way we can correctly account for a
749 * fallocated page arriving here is now to initialize it and write it.
751 * That's okay for a page already fallocated earlier, but if we have
752 * not yet completed the fallocation, then (a) we want to keep track
753 * of this page in case we have to undo it, and (b) it may not be a
754 * good idea to continue anyway, once we're pushing into swap. So
755 * reactivate the page, and let shmem_fallocate() quit when too many.
757 if (!PageUptodate(page
)) {
758 if (inode
->i_private
) {
759 struct shmem_falloc
*shmem_falloc
;
760 spin_lock(&inode
->i_lock
);
761 shmem_falloc
= inode
->i_private
;
763 !shmem_falloc
->mode
&&
764 index
>= shmem_falloc
->start
&&
765 index
< shmem_falloc
->next
)
766 shmem_falloc
->nr_unswapped
++;
769 spin_unlock(&inode
->i_lock
);
773 clear_highpage(page
);
774 flush_dcache_page(page
);
775 SetPageUptodate(page
);
778 swap
= get_swap_page();
783 * Add inode to shmem_unuse()'s list of swapped-out inodes,
784 * if it's not already there. Do it now before the page is
785 * moved to swap cache, when its pagelock no longer protects
786 * the inode from eviction. But don't unlock the mutex until
787 * we've incremented swapped, because shmem_unuse_inode() will
788 * prune a !swapped inode from the swaplist under this mutex.
790 mutex_lock(&shmem_swaplist_mutex
);
791 if (list_empty(&info
->swaplist
))
792 list_add_tail(&info
->swaplist
, &shmem_swaplist
);
794 if (add_to_swap_cache(page
, swap
, GFP_ATOMIC
) == 0) {
795 swap_shmem_alloc(swap
);
796 shmem_delete_from_page_cache(page
, swp_to_radix_entry(swap
));
798 spin_lock(&info
->lock
);
800 shmem_recalc_inode(inode
);
801 spin_unlock(&info
->lock
);
803 mutex_unlock(&shmem_swaplist_mutex
);
804 BUG_ON(page_mapped(page
));
805 swap_writepage(page
, wbc
);
809 mutex_unlock(&shmem_swaplist_mutex
);
810 swapcache_free(swap
, NULL
);
812 set_page_dirty(page
);
813 if (wbc
->for_reclaim
)
814 return AOP_WRITEPAGE_ACTIVATE
; /* Return with page locked */
821 static void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
825 if (!mpol
|| mpol
->mode
== MPOL_DEFAULT
)
826 return; /* show nothing */
828 mpol_to_str(buffer
, sizeof(buffer
), mpol
);
830 seq_printf(seq
, ",mpol=%s", buffer
);
833 static struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
835 struct mempolicy
*mpol
= NULL
;
837 spin_lock(&sbinfo
->stat_lock
); /* prevent replace/use races */
840 spin_unlock(&sbinfo
->stat_lock
);
844 #endif /* CONFIG_TMPFS */
846 static struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
847 struct shmem_inode_info
*info
, pgoff_t index
)
849 struct vm_area_struct pvma
;
852 /* Create a pseudo vma that just contains the policy */
854 /* Bias interleave by inode number to distribute better across nodes */
855 pvma
.vm_pgoff
= index
+ info
->vfs_inode
.i_ino
;
857 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, index
);
859 page
= swapin_readahead(swap
, gfp
, &pvma
, 0);
861 /* Drop reference taken by mpol_shared_policy_lookup() */
862 mpol_cond_put(pvma
.vm_policy
);
867 static struct page
*shmem_alloc_page(gfp_t gfp
,
868 struct shmem_inode_info
*info
, pgoff_t index
)
870 struct vm_area_struct pvma
;
873 /* Create a pseudo vma that just contains the policy */
875 /* Bias interleave by inode number to distribute better across nodes */
876 pvma
.vm_pgoff
= index
+ info
->vfs_inode
.i_ino
;
878 pvma
.vm_policy
= mpol_shared_policy_lookup(&info
->policy
, index
);
880 page
= alloc_page_vma(gfp
, &pvma
, 0);
882 /* Drop reference taken by mpol_shared_policy_lookup() */
883 mpol_cond_put(pvma
.vm_policy
);
887 #else /* !CONFIG_NUMA */
889 static inline void shmem_show_mpol(struct seq_file
*seq
, struct mempolicy
*mpol
)
892 #endif /* CONFIG_TMPFS */
894 static inline struct page
*shmem_swapin(swp_entry_t swap
, gfp_t gfp
,
895 struct shmem_inode_info
*info
, pgoff_t index
)
897 return swapin_readahead(swap
, gfp
, NULL
, 0);
900 static inline struct page
*shmem_alloc_page(gfp_t gfp
,
901 struct shmem_inode_info
*info
, pgoff_t index
)
903 return alloc_page(gfp
);
905 #endif /* CONFIG_NUMA */
907 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
908 static inline struct mempolicy
*shmem_get_sbmpol(struct shmem_sb_info
*sbinfo
)
915 * When a page is moved from swapcache to shmem filecache (either by the
916 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
917 * shmem_unuse_inode()), it may have been read in earlier from swap, in
918 * ignorance of the mapping it belongs to. If that mapping has special
919 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
920 * we may need to copy to a suitable page before moving to filecache.
922 * In a future release, this may well be extended to respect cpuset and
923 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
924 * but for now it is a simple matter of zone.
926 static bool shmem_should_replace_page(struct page
*page
, gfp_t gfp
)
928 return page_zonenum(page
) > gfp_zone(gfp
);
931 static int shmem_replace_page(struct page
**pagep
, gfp_t gfp
,
932 struct shmem_inode_info
*info
, pgoff_t index
)
934 struct page
*oldpage
, *newpage
;
935 struct address_space
*swap_mapping
;
940 swap_index
= page_private(oldpage
);
941 swap_mapping
= page_mapping(oldpage
);
944 * We have arrived here because our zones are constrained, so don't
945 * limit chance of success by further cpuset and node constraints.
947 gfp
&= ~GFP_CONSTRAINT_MASK
;
948 newpage
= shmem_alloc_page(gfp
, info
, index
);
952 page_cache_get(newpage
);
953 copy_highpage(newpage
, oldpage
);
954 flush_dcache_page(newpage
);
956 __set_page_locked(newpage
);
957 SetPageUptodate(newpage
);
958 SetPageSwapBacked(newpage
);
959 set_page_private(newpage
, swap_index
);
960 SetPageSwapCache(newpage
);
963 * Our caller will very soon move newpage out of swapcache, but it's
964 * a nice clean interface for us to replace oldpage by newpage there.
966 spin_lock_irq(&swap_mapping
->tree_lock
);
967 error
= shmem_radix_tree_replace(swap_mapping
, swap_index
, oldpage
,
970 __inc_zone_page_state(newpage
, NR_FILE_PAGES
);
971 __dec_zone_page_state(oldpage
, NR_FILE_PAGES
);
973 spin_unlock_irq(&swap_mapping
->tree_lock
);
975 if (unlikely(error
)) {
977 * Is this possible? I think not, now that our callers check
978 * both PageSwapCache and page_private after getting page lock;
979 * but be defensive. Reverse old to newpage for clear and free.
983 mem_cgroup_replace_page_cache(oldpage
, newpage
);
984 lru_cache_add_anon(newpage
);
988 ClearPageSwapCache(oldpage
);
989 set_page_private(oldpage
, 0);
991 unlock_page(oldpage
);
992 page_cache_release(oldpage
);
993 page_cache_release(oldpage
);
998 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1000 * If we allocate a new one we do not mark it dirty. That's up to the
1001 * vm. If we swap it in we mark it dirty since we also free the swap
1002 * entry since a page cannot live in both the swap and page cache
1004 static int shmem_getpage_gfp(struct inode
*inode
, pgoff_t index
,
1005 struct page
**pagep
, enum sgp_type sgp
, gfp_t gfp
, int *fault_type
)
1007 struct address_space
*mapping
= inode
->i_mapping
;
1008 struct shmem_inode_info
*info
;
1009 struct shmem_sb_info
*sbinfo
;
1016 if (index
> (MAX_LFS_FILESIZE
>> PAGE_CACHE_SHIFT
))
1020 page
= find_lock_entry(mapping
, index
);
1021 if (radix_tree_exceptional_entry(page
)) {
1022 swap
= radix_to_swp_entry(page
);
1026 if (sgp
!= SGP_WRITE
&& sgp
!= SGP_FALLOC
&&
1027 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1032 if (page
&& sgp
== SGP_WRITE
)
1033 mark_page_accessed(page
);
1035 /* fallocated page? */
1036 if (page
&& !PageUptodate(page
)) {
1037 if (sgp
!= SGP_READ
)
1040 page_cache_release(page
);
1043 if (page
|| (sgp
== SGP_READ
&& !swap
.val
)) {
1049 * Fast cache lookup did not find it:
1050 * bring it back from swap or allocate.
1052 info
= SHMEM_I(inode
);
1053 sbinfo
= SHMEM_SB(inode
->i_sb
);
1056 /* Look it up and read it in.. */
1057 page
= lookup_swap_cache(swap
);
1059 /* here we actually do the io */
1061 *fault_type
|= VM_FAULT_MAJOR
;
1062 page
= shmem_swapin(swap
, gfp
, info
, index
);
1069 /* We have to do this with page locked to prevent races */
1071 if (!PageSwapCache(page
) || page_private(page
) != swap
.val
||
1072 !shmem_confirm_swap(mapping
, index
, swap
)) {
1073 error
= -EEXIST
; /* try again */
1076 if (!PageUptodate(page
)) {
1080 wait_on_page_writeback(page
);
1082 if (shmem_should_replace_page(page
, gfp
)) {
1083 error
= shmem_replace_page(&page
, gfp
, info
, index
);
1088 error
= mem_cgroup_charge_file(page
, current
->mm
,
1089 gfp
& GFP_RECLAIM_MASK
);
1091 error
= shmem_add_to_page_cache(page
, mapping
, index
,
1092 gfp
, swp_to_radix_entry(swap
));
1094 * We already confirmed swap under page lock, and make
1095 * no memory allocation here, so usually no possibility
1096 * of error; but free_swap_and_cache() only trylocks a
1097 * page, so it is just possible that the entry has been
1098 * truncated or holepunched since swap was confirmed.
1099 * shmem_undo_range() will have done some of the
1100 * unaccounting, now delete_from_swap_cache() will do
1101 * the rest (including mem_cgroup_uncharge_swapcache).
1102 * Reset swap.val? No, leave it so "failed" goes back to
1103 * "repeat": reading a hole and writing should succeed.
1106 delete_from_swap_cache(page
);
1111 spin_lock(&info
->lock
);
1113 shmem_recalc_inode(inode
);
1114 spin_unlock(&info
->lock
);
1116 if (sgp
== SGP_WRITE
)
1117 mark_page_accessed(page
);
1119 delete_from_swap_cache(page
);
1120 set_page_dirty(page
);
1124 if (shmem_acct_block(info
->flags
)) {
1128 if (sbinfo
->max_blocks
) {
1129 if (percpu_counter_compare(&sbinfo
->used_blocks
,
1130 sbinfo
->max_blocks
) >= 0) {
1134 percpu_counter_inc(&sbinfo
->used_blocks
);
1137 page
= shmem_alloc_page(gfp
, info
, index
);
1143 __SetPageSwapBacked(page
);
1144 __set_page_locked(page
);
1145 if (sgp
== SGP_WRITE
)
1146 init_page_accessed(page
);
1148 error
= mem_cgroup_charge_file(page
, current
->mm
,
1149 gfp
& GFP_RECLAIM_MASK
);
1152 error
= radix_tree_maybe_preload(gfp
& GFP_RECLAIM_MASK
);
1154 error
= shmem_add_to_page_cache(page
, mapping
, index
,
1156 radix_tree_preload_end();
1159 mem_cgroup_uncharge_cache_page(page
);
1162 lru_cache_add_anon(page
);
1164 spin_lock(&info
->lock
);
1166 inode
->i_blocks
+= BLOCKS_PER_PAGE
;
1167 shmem_recalc_inode(inode
);
1168 spin_unlock(&info
->lock
);
1172 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1174 if (sgp
== SGP_FALLOC
)
1178 * Let SGP_WRITE caller clear ends if write does not fill page;
1179 * but SGP_FALLOC on a page fallocated earlier must initialize
1180 * it now, lest undo on failure cancel our earlier guarantee.
1182 if (sgp
!= SGP_WRITE
) {
1183 clear_highpage(page
);
1184 flush_dcache_page(page
);
1185 SetPageUptodate(page
);
1187 if (sgp
== SGP_DIRTY
)
1188 set_page_dirty(page
);
1191 /* Perhaps the file has been truncated since we checked */
1192 if (sgp
!= SGP_WRITE
&& sgp
!= SGP_FALLOC
&&
1193 ((loff_t
)index
<< PAGE_CACHE_SHIFT
) >= i_size_read(inode
)) {
1207 info
= SHMEM_I(inode
);
1208 ClearPageDirty(page
);
1209 delete_from_page_cache(page
);
1210 spin_lock(&info
->lock
);
1212 inode
->i_blocks
-= BLOCKS_PER_PAGE
;
1213 spin_unlock(&info
->lock
);
1215 sbinfo
= SHMEM_SB(inode
->i_sb
);
1216 if (sbinfo
->max_blocks
)
1217 percpu_counter_add(&sbinfo
->used_blocks
, -1);
1219 shmem_unacct_blocks(info
->flags
, 1);
1221 if (swap
.val
&& error
!= -EINVAL
&&
1222 !shmem_confirm_swap(mapping
, index
, swap
))
1227 page_cache_release(page
);
1229 if (error
== -ENOSPC
&& !once
++) {
1230 info
= SHMEM_I(inode
);
1231 spin_lock(&info
->lock
);
1232 shmem_recalc_inode(inode
);
1233 spin_unlock(&info
->lock
);
1236 if (error
== -EEXIST
) /* from above or from radix_tree_insert */
1241 static int shmem_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1243 struct inode
*inode
= file_inode(vma
->vm_file
);
1245 int ret
= VM_FAULT_LOCKED
;
1248 * Trinity finds that probing a hole which tmpfs is punching can
1249 * prevent the hole-punch from ever completing: which in turn
1250 * locks writers out with its hold on i_mutex. So refrain from
1251 * faulting pages into the hole while it's being punched, and
1252 * wait on i_mutex to be released if vmf->flags permits.
1254 if (unlikely(inode
->i_private
)) {
1255 struct shmem_falloc
*shmem_falloc
;
1257 spin_lock(&inode
->i_lock
);
1258 shmem_falloc
= inode
->i_private
;
1259 if (!shmem_falloc
||
1260 shmem_falloc
->mode
!= FALLOC_FL_PUNCH_HOLE
||
1261 vmf
->pgoff
< shmem_falloc
->start
||
1262 vmf
->pgoff
>= shmem_falloc
->next
)
1263 shmem_falloc
= NULL
;
1264 spin_unlock(&inode
->i_lock
);
1266 * i_lock has protected us from taking shmem_falloc seriously
1267 * once return from shmem_fallocate() went back up that stack.
1268 * i_lock does not serialize with i_mutex at all, but it does
1269 * not matter if sometimes we wait unnecessarily, or sometimes
1270 * miss out on waiting: we just need to make those cases rare.
1273 if ((vmf
->flags
& FAULT_FLAG_ALLOW_RETRY
) &&
1274 !(vmf
->flags
& FAULT_FLAG_RETRY_NOWAIT
)) {
1275 up_read(&vma
->vm_mm
->mmap_sem
);
1276 mutex_lock(&inode
->i_mutex
);
1277 mutex_unlock(&inode
->i_mutex
);
1278 return VM_FAULT_RETRY
;
1280 /* cond_resched? Leave that to GUP or return to user */
1281 return VM_FAULT_NOPAGE
;
1285 error
= shmem_getpage(inode
, vmf
->pgoff
, &vmf
->page
, SGP_CACHE
, &ret
);
1287 return ((error
== -ENOMEM
) ? VM_FAULT_OOM
: VM_FAULT_SIGBUS
);
1289 if (ret
& VM_FAULT_MAJOR
) {
1290 count_vm_event(PGMAJFAULT
);
1291 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1297 static int shmem_set_policy(struct vm_area_struct
*vma
, struct mempolicy
*mpol
)
1299 struct inode
*inode
= file_inode(vma
->vm_file
);
1300 return mpol_set_shared_policy(&SHMEM_I(inode
)->policy
, vma
, mpol
);
1303 static struct mempolicy
*shmem_get_policy(struct vm_area_struct
*vma
,
1306 struct inode
*inode
= file_inode(vma
->vm_file
);
1309 index
= ((addr
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
1310 return mpol_shared_policy_lookup(&SHMEM_I(inode
)->policy
, index
);
1314 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
1316 struct inode
*inode
= file_inode(file
);
1317 struct shmem_inode_info
*info
= SHMEM_I(inode
);
1318 int retval
= -ENOMEM
;
1320 spin_lock(&info
->lock
);
1321 if (lock
&& !(info
->flags
& VM_LOCKED
)) {
1322 if (!user_shm_lock(inode
->i_size
, user
))
1324 info
->flags
|= VM_LOCKED
;
1325 mapping_set_unevictable(file
->f_mapping
);
1327 if (!lock
&& (info
->flags
& VM_LOCKED
) && user
) {
1328 user_shm_unlock(inode
->i_size
, user
);
1329 info
->flags
&= ~VM_LOCKED
;
1330 mapping_clear_unevictable(file
->f_mapping
);
1335 spin_unlock(&info
->lock
);
1339 static int shmem_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1341 file_accessed(file
);
1342 vma
->vm_ops
= &shmem_vm_ops
;
1346 static struct inode
*shmem_get_inode(struct super_block
*sb
, const struct inode
*dir
,
1347 umode_t mode
, dev_t dev
, unsigned long flags
)
1349 struct inode
*inode
;
1350 struct shmem_inode_info
*info
;
1351 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
1353 if (shmem_reserve_inode(sb
))
1356 inode
= new_inode(sb
);
1358 inode
->i_ino
= get_next_ino();
1359 inode_init_owner(inode
, dir
, mode
);
1360 inode
->i_blocks
= 0;
1361 inode
->i_mapping
->backing_dev_info
= &shmem_backing_dev_info
;
1362 inode
->i_atime
= inode
->i_mtime
= inode
->i_ctime
= CURRENT_TIME
;
1363 inode
->i_generation
= get_seconds();
1364 info
= SHMEM_I(inode
);
1365 memset(info
, 0, (char *)inode
- (char *)info
);
1366 spin_lock_init(&info
->lock
);
1367 info
->flags
= flags
& VM_NORESERVE
;
1368 INIT_LIST_HEAD(&info
->swaplist
);
1369 simple_xattrs_init(&info
->xattrs
);
1370 cache_no_acl(inode
);
1372 switch (mode
& S_IFMT
) {
1374 inode
->i_op
= &shmem_special_inode_operations
;
1375 init_special_inode(inode
, mode
, dev
);
1378 inode
->i_mapping
->a_ops
= &shmem_aops
;
1379 inode
->i_op
= &shmem_inode_operations
;
1380 inode
->i_fop
= &shmem_file_operations
;
1381 mpol_shared_policy_init(&info
->policy
,
1382 shmem_get_sbmpol(sbinfo
));
1386 /* Some things misbehave if size == 0 on a directory */
1387 inode
->i_size
= 2 * BOGO_DIRENT_SIZE
;
1388 inode
->i_op
= &shmem_dir_inode_operations
;
1389 inode
->i_fop
= &simple_dir_operations
;
1393 * Must not load anything in the rbtree,
1394 * mpol_free_shared_policy will not be called.
1396 mpol_shared_policy_init(&info
->policy
, NULL
);
1400 shmem_free_inode(sb
);
1404 bool shmem_mapping(struct address_space
*mapping
)
1406 return mapping
->backing_dev_info
== &shmem_backing_dev_info
;
1410 static const struct inode_operations shmem_symlink_inode_operations
;
1411 static const struct inode_operations shmem_short_symlink_operations
;
1413 #ifdef CONFIG_TMPFS_XATTR
1414 static int shmem_initxattrs(struct inode
*, const struct xattr
*, void *);
1416 #define shmem_initxattrs NULL
1420 shmem_write_begin(struct file
*file
, struct address_space
*mapping
,
1421 loff_t pos
, unsigned len
, unsigned flags
,
1422 struct page
**pagep
, void **fsdata
)
1424 struct inode
*inode
= mapping
->host
;
1425 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
1426 return shmem_getpage(inode
, index
, pagep
, SGP_WRITE
, NULL
);
1430 shmem_write_end(struct file
*file
, struct address_space
*mapping
,
1431 loff_t pos
, unsigned len
, unsigned copied
,
1432 struct page
*page
, void *fsdata
)
1434 struct inode
*inode
= mapping
->host
;
1436 if (pos
+ copied
> inode
->i_size
)
1437 i_size_write(inode
, pos
+ copied
);
1439 if (!PageUptodate(page
)) {
1440 if (copied
< PAGE_CACHE_SIZE
) {
1441 unsigned from
= pos
& (PAGE_CACHE_SIZE
- 1);
1442 zero_user_segments(page
, 0, from
,
1443 from
+ copied
, PAGE_CACHE_SIZE
);
1445 SetPageUptodate(page
);
1447 set_page_dirty(page
);
1449 page_cache_release(page
);
1454 static ssize_t
shmem_file_read_iter(struct kiocb
*iocb
, struct iov_iter
*to
)
1456 struct file
*file
= iocb
->ki_filp
;
1457 struct inode
*inode
= file_inode(file
);
1458 struct address_space
*mapping
= inode
->i_mapping
;
1460 unsigned long offset
;
1461 enum sgp_type sgp
= SGP_READ
;
1464 loff_t
*ppos
= &iocb
->ki_pos
;
1467 * Might this read be for a stacking filesystem? Then when reading
1468 * holes of a sparse file, we actually need to allocate those pages,
1469 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1471 if (segment_eq(get_fs(), KERNEL_DS
))
1474 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1475 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1478 struct page
*page
= NULL
;
1480 unsigned long nr
, ret
;
1481 loff_t i_size
= i_size_read(inode
);
1483 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1484 if (index
> end_index
)
1486 if (index
== end_index
) {
1487 nr
= i_size
& ~PAGE_CACHE_MASK
;
1492 error
= shmem_getpage(inode
, index
, &page
, sgp
, NULL
);
1494 if (error
== -EINVAL
)
1502 * We must evaluate after, since reads (unlike writes)
1503 * are called without i_mutex protection against truncate
1505 nr
= PAGE_CACHE_SIZE
;
1506 i_size
= i_size_read(inode
);
1507 end_index
= i_size
>> PAGE_CACHE_SHIFT
;
1508 if (index
== end_index
) {
1509 nr
= i_size
& ~PAGE_CACHE_MASK
;
1512 page_cache_release(page
);
1520 * If users can be writing to this page using arbitrary
1521 * virtual addresses, take care about potential aliasing
1522 * before reading the page on the kernel side.
1524 if (mapping_writably_mapped(mapping
))
1525 flush_dcache_page(page
);
1527 * Mark the page accessed if we read the beginning.
1530 mark_page_accessed(page
);
1532 page
= ZERO_PAGE(0);
1533 page_cache_get(page
);
1537 * Ok, we have the page, and it's up-to-date, so
1538 * now we can copy it to user space...
1540 ret
= copy_page_to_iter(page
, offset
, nr
, to
);
1543 index
+= offset
>> PAGE_CACHE_SHIFT
;
1544 offset
&= ~PAGE_CACHE_MASK
;
1546 page_cache_release(page
);
1547 if (!iov_iter_count(to
))
1556 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1557 file_accessed(file
);
1558 return retval
? retval
: error
;
1561 static ssize_t
shmem_file_splice_read(struct file
*in
, loff_t
*ppos
,
1562 struct pipe_inode_info
*pipe
, size_t len
,
1565 struct address_space
*mapping
= in
->f_mapping
;
1566 struct inode
*inode
= mapping
->host
;
1567 unsigned int loff
, nr_pages
, req_pages
;
1568 struct page
*pages
[PIPE_DEF_BUFFERS
];
1569 struct partial_page partial
[PIPE_DEF_BUFFERS
];
1571 pgoff_t index
, end_index
;
1574 struct splice_pipe_desc spd
= {
1577 .nr_pages_max
= PIPE_DEF_BUFFERS
,
1579 .ops
= &page_cache_pipe_buf_ops
,
1580 .spd_release
= spd_release_page
,
1583 isize
= i_size_read(inode
);
1584 if (unlikely(*ppos
>= isize
))
1587 left
= isize
- *ppos
;
1588 if (unlikely(left
< len
))
1591 if (splice_grow_spd(pipe
, &spd
))
1594 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1595 loff
= *ppos
& ~PAGE_CACHE_MASK
;
1596 req_pages
= (len
+ loff
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1597 nr_pages
= min(req_pages
, spd
.nr_pages_max
);
1599 spd
.nr_pages
= find_get_pages_contig(mapping
, index
,
1600 nr_pages
, spd
.pages
);
1601 index
+= spd
.nr_pages
;
1604 while (spd
.nr_pages
< nr_pages
) {
1605 error
= shmem_getpage(inode
, index
, &page
, SGP_CACHE
, NULL
);
1609 spd
.pages
[spd
.nr_pages
++] = page
;
1613 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1614 nr_pages
= spd
.nr_pages
;
1617 for (page_nr
= 0; page_nr
< nr_pages
; page_nr
++) {
1618 unsigned int this_len
;
1623 this_len
= min_t(unsigned long, len
, PAGE_CACHE_SIZE
- loff
);
1624 page
= spd
.pages
[page_nr
];
1626 if (!PageUptodate(page
) || page
->mapping
!= mapping
) {
1627 error
= shmem_getpage(inode
, index
, &page
,
1632 page_cache_release(spd
.pages
[page_nr
]);
1633 spd
.pages
[page_nr
] = page
;
1636 isize
= i_size_read(inode
);
1637 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1638 if (unlikely(!isize
|| index
> end_index
))
1641 if (end_index
== index
) {
1644 plen
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1648 this_len
= min(this_len
, plen
- loff
);
1652 spd
.partial
[page_nr
].offset
= loff
;
1653 spd
.partial
[page_nr
].len
= this_len
;
1660 while (page_nr
< nr_pages
)
1661 page_cache_release(spd
.pages
[page_nr
++]);
1664 error
= splice_to_pipe(pipe
, &spd
);
1666 splice_shrink_spd(&spd
);
1676 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
1678 static pgoff_t
shmem_seek_hole_data(struct address_space
*mapping
,
1679 pgoff_t index
, pgoff_t end
, int whence
)
1682 struct pagevec pvec
;
1683 pgoff_t indices
[PAGEVEC_SIZE
];
1687 pagevec_init(&pvec
, 0);
1688 pvec
.nr
= 1; /* start small: we may be there already */
1690 pvec
.nr
= find_get_entries(mapping
, index
,
1691 pvec
.nr
, pvec
.pages
, indices
);
1693 if (whence
== SEEK_DATA
)
1697 for (i
= 0; i
< pvec
.nr
; i
++, index
++) {
1698 if (index
< indices
[i
]) {
1699 if (whence
== SEEK_HOLE
) {
1705 page
= pvec
.pages
[i
];
1706 if (page
&& !radix_tree_exceptional_entry(page
)) {
1707 if (!PageUptodate(page
))
1711 (page
&& whence
== SEEK_DATA
) ||
1712 (!page
&& whence
== SEEK_HOLE
)) {
1717 pagevec_remove_exceptionals(&pvec
);
1718 pagevec_release(&pvec
);
1719 pvec
.nr
= PAGEVEC_SIZE
;
1725 static loff_t
shmem_file_llseek(struct file
*file
, loff_t offset
, int whence
)
1727 struct address_space
*mapping
= file
->f_mapping
;
1728 struct inode
*inode
= mapping
->host
;
1732 if (whence
!= SEEK_DATA
&& whence
!= SEEK_HOLE
)
1733 return generic_file_llseek_size(file
, offset
, whence
,
1734 MAX_LFS_FILESIZE
, i_size_read(inode
));
1735 mutex_lock(&inode
->i_mutex
);
1736 /* We're holding i_mutex so we can access i_size directly */
1740 else if (offset
>= inode
->i_size
)
1743 start
= offset
>> PAGE_CACHE_SHIFT
;
1744 end
= (inode
->i_size
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1745 new_offset
= shmem_seek_hole_data(mapping
, start
, end
, whence
);
1746 new_offset
<<= PAGE_CACHE_SHIFT
;
1747 if (new_offset
> offset
) {
1748 if (new_offset
< inode
->i_size
)
1749 offset
= new_offset
;
1750 else if (whence
== SEEK_DATA
)
1753 offset
= inode
->i_size
;
1758 offset
= vfs_setpos(file
, offset
, MAX_LFS_FILESIZE
);
1759 mutex_unlock(&inode
->i_mutex
);
1763 static long shmem_fallocate(struct file
*file
, int mode
, loff_t offset
,
1766 struct inode
*inode
= file_inode(file
);
1767 struct shmem_sb_info
*sbinfo
= SHMEM_SB(inode
->i_sb
);
1768 struct shmem_falloc shmem_falloc
;
1769 pgoff_t start
, index
, end
;
1772 if (mode
& ~(FALLOC_FL_KEEP_SIZE
| FALLOC_FL_PUNCH_HOLE
))
1775 mutex_lock(&inode
->i_mutex
);
1777 shmem_falloc
.mode
= mode
& ~FALLOC_FL_KEEP_SIZE
;
1779 if (mode
& FALLOC_FL_PUNCH_HOLE
) {
1780 struct address_space
*mapping
= file
->f_mapping
;
1781 loff_t unmap_start
= round_up(offset
, PAGE_SIZE
);
1782 loff_t unmap_end
= round_down(offset
+ len
, PAGE_SIZE
) - 1;
1784 shmem_falloc
.start
= unmap_start
>> PAGE_SHIFT
;
1785 shmem_falloc
.next
= (unmap_end
+ 1) >> PAGE_SHIFT
;
1786 spin_lock(&inode
->i_lock
);
1787 inode
->i_private
= &shmem_falloc
;
1788 spin_unlock(&inode
->i_lock
);
1790 if ((u64
)unmap_end
> (u64
)unmap_start
)
1791 unmap_mapping_range(mapping
, unmap_start
,
1792 1 + unmap_end
- unmap_start
, 0);
1793 shmem_truncate_range(inode
, offset
, offset
+ len
- 1);
1794 /* No need to unmap again: hole-punching leaves COWed pages */
1799 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1800 error
= inode_newsize_ok(inode
, offset
+ len
);
1804 start
= offset
>> PAGE_CACHE_SHIFT
;
1805 end
= (offset
+ len
+ PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1806 /* Try to avoid a swapstorm if len is impossible to satisfy */
1807 if (sbinfo
->max_blocks
&& end
- start
> sbinfo
->max_blocks
) {
1812 shmem_falloc
.start
= start
;
1813 shmem_falloc
.next
= start
;
1814 shmem_falloc
.nr_falloced
= 0;
1815 shmem_falloc
.nr_unswapped
= 0;
1816 spin_lock(&inode
->i_lock
);
1817 inode
->i_private
= &shmem_falloc
;
1818 spin_unlock(&inode
->i_lock
);
1820 for (index
= start
; index
< end
; index
++) {
1824 * Good, the fallocate(2) manpage permits EINTR: we may have
1825 * been interrupted because we are using up too much memory.
1827 if (signal_pending(current
))
1829 else if (shmem_falloc
.nr_unswapped
> shmem_falloc
.nr_falloced
)
1832 error
= shmem_getpage(inode
, index
, &page
, SGP_FALLOC
,
1835 /* Remove the !PageUptodate pages we added */
1836 shmem_undo_range(inode
,
1837 (loff_t
)start
<< PAGE_CACHE_SHIFT
,
1838 (loff_t
)index
<< PAGE_CACHE_SHIFT
, true);
1843 * Inform shmem_writepage() how far we have reached.
1844 * No need for lock or barrier: we have the page lock.
1846 shmem_falloc
.next
++;
1847 if (!PageUptodate(page
))
1848 shmem_falloc
.nr_falloced
++;
1851 * If !PageUptodate, leave it that way so that freeable pages
1852 * can be recognized if we need to rollback on error later.
1853 * But set_page_dirty so that memory pressure will swap rather
1854 * than free the pages we are allocating (and SGP_CACHE pages
1855 * might still be clean: we now need to mark those dirty too).
1857 set_page_dirty(page
);
1859 page_cache_release(page
);
1863 if (!(mode
& FALLOC_FL_KEEP_SIZE
) && offset
+ len
> inode
->i_size
)
1864 i_size_write(inode
, offset
+ len
);
1865 inode
->i_ctime
= CURRENT_TIME
;
1867 spin_lock(&inode
->i_lock
);
1868 inode
->i_private
= NULL
;
1869 spin_unlock(&inode
->i_lock
);
1871 mutex_unlock(&inode
->i_mutex
);
1875 static int shmem_statfs(struct dentry
*dentry
, struct kstatfs
*buf
)
1877 struct shmem_sb_info
*sbinfo
= SHMEM_SB(dentry
->d_sb
);
1879 buf
->f_type
= TMPFS_MAGIC
;
1880 buf
->f_bsize
= PAGE_CACHE_SIZE
;
1881 buf
->f_namelen
= NAME_MAX
;
1882 if (sbinfo
->max_blocks
) {
1883 buf
->f_blocks
= sbinfo
->max_blocks
;
1885 buf
->f_bfree
= sbinfo
->max_blocks
-
1886 percpu_counter_sum(&sbinfo
->used_blocks
);
1888 if (sbinfo
->max_inodes
) {
1889 buf
->f_files
= sbinfo
->max_inodes
;
1890 buf
->f_ffree
= sbinfo
->free_inodes
;
1892 /* else leave those fields 0 like simple_statfs */
1897 * File creation. Allocate an inode, and we're done..
1900 shmem_mknod(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
, dev_t dev
)
1902 struct inode
*inode
;
1903 int error
= -ENOSPC
;
1905 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, dev
, VM_NORESERVE
);
1907 error
= simple_acl_create(dir
, inode
);
1910 error
= security_inode_init_security(inode
, dir
,
1912 shmem_initxattrs
, NULL
);
1913 if (error
&& error
!= -EOPNOTSUPP
)
1917 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1918 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1919 d_instantiate(dentry
, inode
);
1920 dget(dentry
); /* Extra count - pin the dentry in core */
1929 shmem_tmpfile(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
1931 struct inode
*inode
;
1932 int error
= -ENOSPC
;
1934 inode
= shmem_get_inode(dir
->i_sb
, dir
, mode
, 0, VM_NORESERVE
);
1936 error
= security_inode_init_security(inode
, dir
,
1938 shmem_initxattrs
, NULL
);
1939 if (error
&& error
!= -EOPNOTSUPP
)
1941 error
= simple_acl_create(dir
, inode
);
1944 d_tmpfile(dentry
, inode
);
1952 static int shmem_mkdir(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
)
1956 if ((error
= shmem_mknod(dir
, dentry
, mode
| S_IFDIR
, 0)))
1962 static int shmem_create(struct inode
*dir
, struct dentry
*dentry
, umode_t mode
,
1965 return shmem_mknod(dir
, dentry
, mode
| S_IFREG
, 0);
1971 static int shmem_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*dentry
)
1973 struct inode
*inode
= old_dentry
->d_inode
;
1977 * No ordinary (disk based) filesystem counts links as inodes;
1978 * but each new link needs a new dentry, pinning lowmem, and
1979 * tmpfs dentries cannot be pruned until they are unlinked.
1981 ret
= shmem_reserve_inode(inode
->i_sb
);
1985 dir
->i_size
+= BOGO_DIRENT_SIZE
;
1986 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
1988 ihold(inode
); /* New dentry reference */
1989 dget(dentry
); /* Extra pinning count for the created dentry */
1990 d_instantiate(dentry
, inode
);
1995 static int shmem_unlink(struct inode
*dir
, struct dentry
*dentry
)
1997 struct inode
*inode
= dentry
->d_inode
;
1999 if (inode
->i_nlink
> 1 && !S_ISDIR(inode
->i_mode
))
2000 shmem_free_inode(inode
->i_sb
);
2002 dir
->i_size
-= BOGO_DIRENT_SIZE
;
2003 inode
->i_ctime
= dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2005 dput(dentry
); /* Undo the count from "create" - this does all the work */
2009 static int shmem_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2011 if (!simple_empty(dentry
))
2014 drop_nlink(dentry
->d_inode
);
2016 return shmem_unlink(dir
, dentry
);
2020 * The VFS layer already does all the dentry stuff for rename,
2021 * we just have to decrement the usage count for the target if
2022 * it exists so that the VFS layer correctly free's it when it
2025 static int shmem_rename(struct inode
*old_dir
, struct dentry
*old_dentry
, struct inode
*new_dir
, struct dentry
*new_dentry
)
2027 struct inode
*inode
= old_dentry
->d_inode
;
2028 int they_are_dirs
= S_ISDIR(inode
->i_mode
);
2030 if (!simple_empty(new_dentry
))
2033 if (new_dentry
->d_inode
) {
2034 (void) shmem_unlink(new_dir
, new_dentry
);
2036 drop_nlink(old_dir
);
2037 } else if (they_are_dirs
) {
2038 drop_nlink(old_dir
);
2042 old_dir
->i_size
-= BOGO_DIRENT_SIZE
;
2043 new_dir
->i_size
+= BOGO_DIRENT_SIZE
;
2044 old_dir
->i_ctime
= old_dir
->i_mtime
=
2045 new_dir
->i_ctime
= new_dir
->i_mtime
=
2046 inode
->i_ctime
= CURRENT_TIME
;
2050 static int shmem_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *symname
)
2054 struct inode
*inode
;
2057 struct shmem_inode_info
*info
;
2059 len
= strlen(symname
) + 1;
2060 if (len
> PAGE_CACHE_SIZE
)
2061 return -ENAMETOOLONG
;
2063 inode
= shmem_get_inode(dir
->i_sb
, dir
, S_IFLNK
|S_IRWXUGO
, 0, VM_NORESERVE
);
2067 error
= security_inode_init_security(inode
, dir
, &dentry
->d_name
,
2068 shmem_initxattrs
, NULL
);
2070 if (error
!= -EOPNOTSUPP
) {
2077 info
= SHMEM_I(inode
);
2078 inode
->i_size
= len
-1;
2079 if (len
<= SHORT_SYMLINK_LEN
) {
2080 info
->symlink
= kmemdup(symname
, len
, GFP_KERNEL
);
2081 if (!info
->symlink
) {
2085 inode
->i_op
= &shmem_short_symlink_operations
;
2087 error
= shmem_getpage(inode
, 0, &page
, SGP_WRITE
, NULL
);
2092 inode
->i_mapping
->a_ops
= &shmem_aops
;
2093 inode
->i_op
= &shmem_symlink_inode_operations
;
2094 kaddr
= kmap_atomic(page
);
2095 memcpy(kaddr
, symname
, len
);
2096 kunmap_atomic(kaddr
);
2097 SetPageUptodate(page
);
2098 set_page_dirty(page
);
2100 page_cache_release(page
);
2102 dir
->i_size
+= BOGO_DIRENT_SIZE
;
2103 dir
->i_ctime
= dir
->i_mtime
= CURRENT_TIME
;
2104 d_instantiate(dentry
, inode
);
2109 static void *shmem_follow_short_symlink(struct dentry
*dentry
, struct nameidata
*nd
)
2111 nd_set_link(nd
, SHMEM_I(dentry
->d_inode
)->symlink
);
2115 static void *shmem_follow_link(struct dentry
*dentry
, struct nameidata
*nd
)
2117 struct page
*page
= NULL
;
2118 int error
= shmem_getpage(dentry
->d_inode
, 0, &page
, SGP_READ
, NULL
);
2119 nd_set_link(nd
, error
? ERR_PTR(error
) : kmap(page
));
2125 static void shmem_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2127 if (!IS_ERR(nd_get_link(nd
))) {
2128 struct page
*page
= cookie
;
2130 mark_page_accessed(page
);
2131 page_cache_release(page
);
2135 #ifdef CONFIG_TMPFS_XATTR
2137 * Superblocks without xattr inode operations may get some security.* xattr
2138 * support from the LSM "for free". As soon as we have any other xattrs
2139 * like ACLs, we also need to implement the security.* handlers at
2140 * filesystem level, though.
2144 * Callback for security_inode_init_security() for acquiring xattrs.
2146 static int shmem_initxattrs(struct inode
*inode
,
2147 const struct xattr
*xattr_array
,
2150 struct shmem_inode_info
*info
= SHMEM_I(inode
);
2151 const struct xattr
*xattr
;
2152 struct simple_xattr
*new_xattr
;
2155 for (xattr
= xattr_array
; xattr
->name
!= NULL
; xattr
++) {
2156 new_xattr
= simple_xattr_alloc(xattr
->value
, xattr
->value_len
);
2160 len
= strlen(xattr
->name
) + 1;
2161 new_xattr
->name
= kmalloc(XATTR_SECURITY_PREFIX_LEN
+ len
,
2163 if (!new_xattr
->name
) {
2168 memcpy(new_xattr
->name
, XATTR_SECURITY_PREFIX
,
2169 XATTR_SECURITY_PREFIX_LEN
);
2170 memcpy(new_xattr
->name
+ XATTR_SECURITY_PREFIX_LEN
,
2173 simple_xattr_list_add(&info
->xattrs
, new_xattr
);
2179 static const struct xattr_handler
*shmem_xattr_handlers
[] = {
2180 #ifdef CONFIG_TMPFS_POSIX_ACL
2181 &posix_acl_access_xattr_handler
,
2182 &posix_acl_default_xattr_handler
,
2187 static int shmem_xattr_validate(const char *name
)
2189 struct { const char *prefix
; size_t len
; } arr
[] = {
2190 { XATTR_SECURITY_PREFIX
, XATTR_SECURITY_PREFIX_LEN
},
2191 { XATTR_TRUSTED_PREFIX
, XATTR_TRUSTED_PREFIX_LEN
}
2195 for (i
= 0; i
< ARRAY_SIZE(arr
); i
++) {
2196 size_t preflen
= arr
[i
].len
;
2197 if (strncmp(name
, arr
[i
].prefix
, preflen
) == 0) {
2206 static ssize_t
shmem_getxattr(struct dentry
*dentry
, const char *name
,
2207 void *buffer
, size_t size
)
2209 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2213 * If this is a request for a synthetic attribute in the system.*
2214 * namespace use the generic infrastructure to resolve a handler
2215 * for it via sb->s_xattr.
2217 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2218 return generic_getxattr(dentry
, name
, buffer
, size
);
2220 err
= shmem_xattr_validate(name
);
2224 return simple_xattr_get(&info
->xattrs
, name
, buffer
, size
);
2227 static int shmem_setxattr(struct dentry
*dentry
, const char *name
,
2228 const void *value
, size_t size
, int flags
)
2230 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2234 * If this is a request for a synthetic attribute in the system.*
2235 * namespace use the generic infrastructure to resolve a handler
2236 * for it via sb->s_xattr.
2238 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2239 return generic_setxattr(dentry
, name
, value
, size
, flags
);
2241 err
= shmem_xattr_validate(name
);
2245 return simple_xattr_set(&info
->xattrs
, name
, value
, size
, flags
);
2248 static int shmem_removexattr(struct dentry
*dentry
, const char *name
)
2250 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2254 * If this is a request for a synthetic attribute in the system.*
2255 * namespace use the generic infrastructure to resolve a handler
2256 * for it via sb->s_xattr.
2258 if (!strncmp(name
, XATTR_SYSTEM_PREFIX
, XATTR_SYSTEM_PREFIX_LEN
))
2259 return generic_removexattr(dentry
, name
);
2261 err
= shmem_xattr_validate(name
);
2265 return simple_xattr_remove(&info
->xattrs
, name
);
2268 static ssize_t
shmem_listxattr(struct dentry
*dentry
, char *buffer
, size_t size
)
2270 struct shmem_inode_info
*info
= SHMEM_I(dentry
->d_inode
);
2271 return simple_xattr_list(&info
->xattrs
, buffer
, size
);
2273 #endif /* CONFIG_TMPFS_XATTR */
2275 static const struct inode_operations shmem_short_symlink_operations
= {
2276 .readlink
= generic_readlink
,
2277 .follow_link
= shmem_follow_short_symlink
,
2278 #ifdef CONFIG_TMPFS_XATTR
2279 .setxattr
= shmem_setxattr
,
2280 .getxattr
= shmem_getxattr
,
2281 .listxattr
= shmem_listxattr
,
2282 .removexattr
= shmem_removexattr
,
2286 static const struct inode_operations shmem_symlink_inode_operations
= {
2287 .readlink
= generic_readlink
,
2288 .follow_link
= shmem_follow_link
,
2289 .put_link
= shmem_put_link
,
2290 #ifdef CONFIG_TMPFS_XATTR
2291 .setxattr
= shmem_setxattr
,
2292 .getxattr
= shmem_getxattr
,
2293 .listxattr
= shmem_listxattr
,
2294 .removexattr
= shmem_removexattr
,
2298 static struct dentry
*shmem_get_parent(struct dentry
*child
)
2300 return ERR_PTR(-ESTALE
);
2303 static int shmem_match(struct inode
*ino
, void *vfh
)
2307 inum
= (inum
<< 32) | fh
[1];
2308 return ino
->i_ino
== inum
&& fh
[0] == ino
->i_generation
;
2311 static struct dentry
*shmem_fh_to_dentry(struct super_block
*sb
,
2312 struct fid
*fid
, int fh_len
, int fh_type
)
2314 struct inode
*inode
;
2315 struct dentry
*dentry
= NULL
;
2322 inum
= (inum
<< 32) | fid
->raw
[1];
2324 inode
= ilookup5(sb
, (unsigned long)(inum
+ fid
->raw
[0]),
2325 shmem_match
, fid
->raw
);
2327 dentry
= d_find_alias(inode
);
2334 static int shmem_encode_fh(struct inode
*inode
, __u32
*fh
, int *len
,
2335 struct inode
*parent
)
2339 return FILEID_INVALID
;
2342 if (inode_unhashed(inode
)) {
2343 /* Unfortunately insert_inode_hash is not idempotent,
2344 * so as we hash inodes here rather than at creation
2345 * time, we need a lock to ensure we only try
2348 static DEFINE_SPINLOCK(lock
);
2350 if (inode_unhashed(inode
))
2351 __insert_inode_hash(inode
,
2352 inode
->i_ino
+ inode
->i_generation
);
2356 fh
[0] = inode
->i_generation
;
2357 fh
[1] = inode
->i_ino
;
2358 fh
[2] = ((__u64
)inode
->i_ino
) >> 32;
2364 static const struct export_operations shmem_export_ops
= {
2365 .get_parent
= shmem_get_parent
,
2366 .encode_fh
= shmem_encode_fh
,
2367 .fh_to_dentry
= shmem_fh_to_dentry
,
2370 static int shmem_parse_options(char *options
, struct shmem_sb_info
*sbinfo
,
2373 char *this_char
, *value
, *rest
;
2374 struct mempolicy
*mpol
= NULL
;
2378 while (options
!= NULL
) {
2379 this_char
= options
;
2382 * NUL-terminate this option: unfortunately,
2383 * mount options form a comma-separated list,
2384 * but mpol's nodelist may also contain commas.
2386 options
= strchr(options
, ',');
2387 if (options
== NULL
)
2390 if (!isdigit(*options
)) {
2397 if ((value
= strchr(this_char
,'=')) != NULL
) {
2401 "tmpfs: No value for mount option '%s'\n",
2406 if (!strcmp(this_char
,"size")) {
2407 unsigned long long size
;
2408 size
= memparse(value
,&rest
);
2410 size
<<= PAGE_SHIFT
;
2411 size
*= totalram_pages
;
2417 sbinfo
->max_blocks
=
2418 DIV_ROUND_UP(size
, PAGE_CACHE_SIZE
);
2419 } else if (!strcmp(this_char
,"nr_blocks")) {
2420 sbinfo
->max_blocks
= memparse(value
, &rest
);
2423 } else if (!strcmp(this_char
,"nr_inodes")) {
2424 sbinfo
->max_inodes
= memparse(value
, &rest
);
2427 } else if (!strcmp(this_char
,"mode")) {
2430 sbinfo
->mode
= simple_strtoul(value
, &rest
, 8) & 07777;
2433 } else if (!strcmp(this_char
,"uid")) {
2436 uid
= simple_strtoul(value
, &rest
, 0);
2439 sbinfo
->uid
= make_kuid(current_user_ns(), uid
);
2440 if (!uid_valid(sbinfo
->uid
))
2442 } else if (!strcmp(this_char
,"gid")) {
2445 gid
= simple_strtoul(value
, &rest
, 0);
2448 sbinfo
->gid
= make_kgid(current_user_ns(), gid
);
2449 if (!gid_valid(sbinfo
->gid
))
2451 } else if (!strcmp(this_char
,"mpol")) {
2454 if (mpol_parse_str(value
, &mpol
))
2457 printk(KERN_ERR
"tmpfs: Bad mount option %s\n",
2462 sbinfo
->mpol
= mpol
;
2466 printk(KERN_ERR
"tmpfs: Bad value '%s' for mount option '%s'\n",
2474 static int shmem_remount_fs(struct super_block
*sb
, int *flags
, char *data
)
2476 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2477 struct shmem_sb_info config
= *sbinfo
;
2478 unsigned long inodes
;
2479 int error
= -EINVAL
;
2482 if (shmem_parse_options(data
, &config
, true))
2485 spin_lock(&sbinfo
->stat_lock
);
2486 inodes
= sbinfo
->max_inodes
- sbinfo
->free_inodes
;
2487 if (percpu_counter_compare(&sbinfo
->used_blocks
, config
.max_blocks
) > 0)
2489 if (config
.max_inodes
< inodes
)
2492 * Those tests disallow limited->unlimited while any are in use;
2493 * but we must separately disallow unlimited->limited, because
2494 * in that case we have no record of how much is already in use.
2496 if (config
.max_blocks
&& !sbinfo
->max_blocks
)
2498 if (config
.max_inodes
&& !sbinfo
->max_inodes
)
2502 sbinfo
->max_blocks
= config
.max_blocks
;
2503 sbinfo
->max_inodes
= config
.max_inodes
;
2504 sbinfo
->free_inodes
= config
.max_inodes
- inodes
;
2507 * Preserve previous mempolicy unless mpol remount option was specified.
2510 mpol_put(sbinfo
->mpol
);
2511 sbinfo
->mpol
= config
.mpol
; /* transfers initial ref */
2514 spin_unlock(&sbinfo
->stat_lock
);
2518 static int shmem_show_options(struct seq_file
*seq
, struct dentry
*root
)
2520 struct shmem_sb_info
*sbinfo
= SHMEM_SB(root
->d_sb
);
2522 if (sbinfo
->max_blocks
!= shmem_default_max_blocks())
2523 seq_printf(seq
, ",size=%luk",
2524 sbinfo
->max_blocks
<< (PAGE_CACHE_SHIFT
- 10));
2525 if (sbinfo
->max_inodes
!= shmem_default_max_inodes())
2526 seq_printf(seq
, ",nr_inodes=%lu", sbinfo
->max_inodes
);
2527 if (sbinfo
->mode
!= (S_IRWXUGO
| S_ISVTX
))
2528 seq_printf(seq
, ",mode=%03ho", sbinfo
->mode
);
2529 if (!uid_eq(sbinfo
->uid
, GLOBAL_ROOT_UID
))
2530 seq_printf(seq
, ",uid=%u",
2531 from_kuid_munged(&init_user_ns
, sbinfo
->uid
));
2532 if (!gid_eq(sbinfo
->gid
, GLOBAL_ROOT_GID
))
2533 seq_printf(seq
, ",gid=%u",
2534 from_kgid_munged(&init_user_ns
, sbinfo
->gid
));
2535 shmem_show_mpol(seq
, sbinfo
->mpol
);
2538 #endif /* CONFIG_TMPFS */
2540 static void shmem_put_super(struct super_block
*sb
)
2542 struct shmem_sb_info
*sbinfo
= SHMEM_SB(sb
);
2544 percpu_counter_destroy(&sbinfo
->used_blocks
);
2545 mpol_put(sbinfo
->mpol
);
2547 sb
->s_fs_info
= NULL
;
2550 int shmem_fill_super(struct super_block
*sb
, void *data
, int silent
)
2552 struct inode
*inode
;
2553 struct shmem_sb_info
*sbinfo
;
2556 /* Round up to L1_CACHE_BYTES to resist false sharing */
2557 sbinfo
= kzalloc(max((int)sizeof(struct shmem_sb_info
),
2558 L1_CACHE_BYTES
), GFP_KERNEL
);
2562 sbinfo
->mode
= S_IRWXUGO
| S_ISVTX
;
2563 sbinfo
->uid
= current_fsuid();
2564 sbinfo
->gid
= current_fsgid();
2565 sb
->s_fs_info
= sbinfo
;
2569 * Per default we only allow half of the physical ram per
2570 * tmpfs instance, limiting inodes to one per page of lowmem;
2571 * but the internal instance is left unlimited.
2573 if (!(sb
->s_flags
& MS_KERNMOUNT
)) {
2574 sbinfo
->max_blocks
= shmem_default_max_blocks();
2575 sbinfo
->max_inodes
= shmem_default_max_inodes();
2576 if (shmem_parse_options(data
, sbinfo
, false)) {
2581 sb
->s_flags
|= MS_NOUSER
;
2583 sb
->s_export_op
= &shmem_export_ops
;
2584 sb
->s_flags
|= MS_NOSEC
;
2586 sb
->s_flags
|= MS_NOUSER
;
2589 spin_lock_init(&sbinfo
->stat_lock
);
2590 if (percpu_counter_init(&sbinfo
->used_blocks
, 0))
2592 sbinfo
->free_inodes
= sbinfo
->max_inodes
;
2594 sb
->s_maxbytes
= MAX_LFS_FILESIZE
;
2595 sb
->s_blocksize
= PAGE_CACHE_SIZE
;
2596 sb
->s_blocksize_bits
= PAGE_CACHE_SHIFT
;
2597 sb
->s_magic
= TMPFS_MAGIC
;
2598 sb
->s_op
= &shmem_ops
;
2599 sb
->s_time_gran
= 1;
2600 #ifdef CONFIG_TMPFS_XATTR
2601 sb
->s_xattr
= shmem_xattr_handlers
;
2603 #ifdef CONFIG_TMPFS_POSIX_ACL
2604 sb
->s_flags
|= MS_POSIXACL
;
2607 inode
= shmem_get_inode(sb
, NULL
, S_IFDIR
| sbinfo
->mode
, 0, VM_NORESERVE
);
2610 inode
->i_uid
= sbinfo
->uid
;
2611 inode
->i_gid
= sbinfo
->gid
;
2612 sb
->s_root
= d_make_root(inode
);
2618 shmem_put_super(sb
);
2622 static struct kmem_cache
*shmem_inode_cachep
;
2624 static struct inode
*shmem_alloc_inode(struct super_block
*sb
)
2626 struct shmem_inode_info
*info
;
2627 info
= kmem_cache_alloc(shmem_inode_cachep
, GFP_KERNEL
);
2630 return &info
->vfs_inode
;
2633 static void shmem_destroy_callback(struct rcu_head
*head
)
2635 struct inode
*inode
= container_of(head
, struct inode
, i_rcu
);
2636 kmem_cache_free(shmem_inode_cachep
, SHMEM_I(inode
));
2639 static void shmem_destroy_inode(struct inode
*inode
)
2641 if (S_ISREG(inode
->i_mode
))
2642 mpol_free_shared_policy(&SHMEM_I(inode
)->policy
);
2643 call_rcu(&inode
->i_rcu
, shmem_destroy_callback
);
2646 static void shmem_init_inode(void *foo
)
2648 struct shmem_inode_info
*info
= foo
;
2649 inode_init_once(&info
->vfs_inode
);
2652 static int shmem_init_inodecache(void)
2654 shmem_inode_cachep
= kmem_cache_create("shmem_inode_cache",
2655 sizeof(struct shmem_inode_info
),
2656 0, SLAB_PANIC
, shmem_init_inode
);
2660 static void shmem_destroy_inodecache(void)
2662 kmem_cache_destroy(shmem_inode_cachep
);
2665 static const struct address_space_operations shmem_aops
= {
2666 .writepage
= shmem_writepage
,
2667 .set_page_dirty
= __set_page_dirty_no_writeback
,
2669 .write_begin
= shmem_write_begin
,
2670 .write_end
= shmem_write_end
,
2672 .migratepage
= migrate_page
,
2673 .error_remove_page
= generic_error_remove_page
,
2676 static const struct file_operations shmem_file_operations
= {
2679 .llseek
= shmem_file_llseek
,
2680 .read
= new_sync_read
,
2681 .write
= new_sync_write
,
2682 .read_iter
= shmem_file_read_iter
,
2683 .write_iter
= generic_file_write_iter
,
2684 .fsync
= noop_fsync
,
2685 .splice_read
= shmem_file_splice_read
,
2686 .splice_write
= iter_file_splice_write
,
2687 .fallocate
= shmem_fallocate
,
2691 static const struct inode_operations shmem_inode_operations
= {
2692 .setattr
= shmem_setattr
,
2693 #ifdef CONFIG_TMPFS_XATTR
2694 .setxattr
= shmem_setxattr
,
2695 .getxattr
= shmem_getxattr
,
2696 .listxattr
= shmem_listxattr
,
2697 .removexattr
= shmem_removexattr
,
2698 .set_acl
= simple_set_acl
,
2702 static const struct inode_operations shmem_dir_inode_operations
= {
2704 .create
= shmem_create
,
2705 .lookup
= simple_lookup
,
2707 .unlink
= shmem_unlink
,
2708 .symlink
= shmem_symlink
,
2709 .mkdir
= shmem_mkdir
,
2710 .rmdir
= shmem_rmdir
,
2711 .mknod
= shmem_mknod
,
2712 .rename
= shmem_rename
,
2713 .tmpfile
= shmem_tmpfile
,
2715 #ifdef CONFIG_TMPFS_XATTR
2716 .setxattr
= shmem_setxattr
,
2717 .getxattr
= shmem_getxattr
,
2718 .listxattr
= shmem_listxattr
,
2719 .removexattr
= shmem_removexattr
,
2721 #ifdef CONFIG_TMPFS_POSIX_ACL
2722 .setattr
= shmem_setattr
,
2723 .set_acl
= simple_set_acl
,
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
,
2736 .set_acl
= simple_set_acl
,
2740 static const struct super_operations shmem_ops
= {
2741 .alloc_inode
= shmem_alloc_inode
,
2742 .destroy_inode
= shmem_destroy_inode
,
2744 .statfs
= shmem_statfs
,
2745 .remount_fs
= shmem_remount_fs
,
2746 .show_options
= shmem_show_options
,
2748 .evict_inode
= shmem_evict_inode
,
2749 .drop_inode
= generic_delete_inode
,
2750 .put_super
= shmem_put_super
,
2753 static const struct vm_operations_struct shmem_vm_ops
= {
2754 .fault
= shmem_fault
,
2755 .map_pages
= filemap_map_pages
,
2757 .set_policy
= shmem_set_policy
,
2758 .get_policy
= shmem_get_policy
,
2760 .remap_pages
= generic_file_remap_pages
,
2763 static struct dentry
*shmem_mount(struct file_system_type
*fs_type
,
2764 int flags
, const char *dev_name
, void *data
)
2766 return mount_nodev(fs_type
, flags
, data
, shmem_fill_super
);
2769 static struct file_system_type shmem_fs_type
= {
2770 .owner
= THIS_MODULE
,
2772 .mount
= shmem_mount
,
2773 .kill_sb
= kill_litter_super
,
2774 .fs_flags
= FS_USERNS_MOUNT
,
2777 int __init
shmem_init(void)
2781 /* If rootfs called this, don't re-init */
2782 if (shmem_inode_cachep
)
2785 error
= bdi_init(&shmem_backing_dev_info
);
2789 error
= shmem_init_inodecache();
2793 error
= register_filesystem(&shmem_fs_type
);
2795 printk(KERN_ERR
"Could not register tmpfs\n");
2799 shm_mnt
= kern_mount(&shmem_fs_type
);
2800 if (IS_ERR(shm_mnt
)) {
2801 error
= PTR_ERR(shm_mnt
);
2802 printk(KERN_ERR
"Could not kern_mount tmpfs\n");
2808 unregister_filesystem(&shmem_fs_type
);
2810 shmem_destroy_inodecache();
2812 bdi_destroy(&shmem_backing_dev_info
);
2814 shm_mnt
= ERR_PTR(error
);
2818 #else /* !CONFIG_SHMEM */
2821 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2823 * This is intended for small system where the benefits of the full
2824 * shmem code (swap-backed and resource-limited) are outweighed by
2825 * their complexity. On systems without swap this code should be
2826 * effectively equivalent, but much lighter weight.
2829 static struct file_system_type shmem_fs_type
= {
2831 .mount
= ramfs_mount
,
2832 .kill_sb
= kill_litter_super
,
2833 .fs_flags
= FS_USERNS_MOUNT
,
2836 int __init
shmem_init(void)
2838 BUG_ON(register_filesystem(&shmem_fs_type
) != 0);
2840 shm_mnt
= kern_mount(&shmem_fs_type
);
2841 BUG_ON(IS_ERR(shm_mnt
));
2846 int shmem_unuse(swp_entry_t swap
, struct page
*page
)
2851 int shmem_lock(struct file
*file
, int lock
, struct user_struct
*user
)
2856 void shmem_unlock_mapping(struct address_space
*mapping
)
2860 void shmem_truncate_range(struct inode
*inode
, loff_t lstart
, loff_t lend
)
2862 truncate_inode_pages_range(inode
->i_mapping
, lstart
, lend
);
2864 EXPORT_SYMBOL_GPL(shmem_truncate_range
);
2866 #define shmem_vm_ops generic_file_vm_ops
2867 #define shmem_file_operations ramfs_file_operations
2868 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2869 #define shmem_acct_size(flags, size) 0
2870 #define shmem_unacct_size(flags, size) do {} while (0)
2872 #endif /* CONFIG_SHMEM */
2876 static struct dentry_operations anon_ops
= {
2877 .d_dname
= simple_dname
2880 static struct file
*__shmem_file_setup(const char *name
, loff_t size
,
2881 unsigned long flags
, unsigned int i_flags
)
2884 struct inode
*inode
;
2886 struct super_block
*sb
;
2889 if (IS_ERR(shm_mnt
))
2890 return ERR_CAST(shm_mnt
);
2892 if (size
< 0 || size
> MAX_LFS_FILESIZE
)
2893 return ERR_PTR(-EINVAL
);
2895 if (shmem_acct_size(flags
, size
))
2896 return ERR_PTR(-ENOMEM
);
2898 res
= ERR_PTR(-ENOMEM
);
2900 this.len
= strlen(name
);
2901 this.hash
= 0; /* will go */
2902 sb
= shm_mnt
->mnt_sb
;
2903 path
.dentry
= d_alloc_pseudo(sb
, &this);
2906 d_set_d_op(path
.dentry
, &anon_ops
);
2907 path
.mnt
= mntget(shm_mnt
);
2909 res
= ERR_PTR(-ENOSPC
);
2910 inode
= shmem_get_inode(sb
, NULL
, S_IFREG
| S_IRWXUGO
, 0, flags
);
2914 inode
->i_flags
|= i_flags
;
2915 d_instantiate(path
.dentry
, inode
);
2916 inode
->i_size
= size
;
2917 clear_nlink(inode
); /* It is unlinked */
2918 res
= ERR_PTR(ramfs_nommu_expand_for_mapping(inode
, size
));
2922 res
= alloc_file(&path
, FMODE_WRITE
| FMODE_READ
,
2923 &shmem_file_operations
);
2932 shmem_unacct_size(flags
, size
);
2937 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
2938 * kernel internal. There will be NO LSM permission checks against the
2939 * underlying inode. So users of this interface must do LSM checks at a
2940 * higher layer. The one user is the big_key implementation. LSM checks
2941 * are provided at the key level rather than the inode level.
2942 * @name: name for dentry (to be seen in /proc/<pid>/maps
2943 * @size: size to be set for the file
2944 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2946 struct file
*shmem_kernel_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2948 return __shmem_file_setup(name
, size
, flags
, S_PRIVATE
);
2952 * shmem_file_setup - get an unlinked file living in tmpfs
2953 * @name: name for dentry (to be seen in /proc/<pid>/maps
2954 * @size: size to be set for the file
2955 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2957 struct file
*shmem_file_setup(const char *name
, loff_t size
, unsigned long flags
)
2959 return __shmem_file_setup(name
, size
, flags
, 0);
2961 EXPORT_SYMBOL_GPL(shmem_file_setup
);
2964 * shmem_zero_setup - setup a shared anonymous mapping
2965 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2967 int shmem_zero_setup(struct vm_area_struct
*vma
)
2970 loff_t size
= vma
->vm_end
- vma
->vm_start
;
2972 file
= shmem_file_setup("dev/zero", size
, vma
->vm_flags
);
2974 return PTR_ERR(file
);
2978 vma
->vm_file
= file
;
2979 vma
->vm_ops
= &shmem_vm_ops
;
2984 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
2985 * @mapping: the page's address_space
2986 * @index: the page index
2987 * @gfp: the page allocator flags to use if allocating
2989 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
2990 * with any new page allocations done using the specified allocation flags.
2991 * But read_cache_page_gfp() uses the ->readpage() method: which does not
2992 * suit tmpfs, since it may have pages in swapcache, and needs to find those
2993 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
2995 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
2996 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
2998 struct page
*shmem_read_mapping_page_gfp(struct address_space
*mapping
,
2999 pgoff_t index
, gfp_t gfp
)
3002 struct inode
*inode
= mapping
->host
;
3006 BUG_ON(mapping
->a_ops
!= &shmem_aops
);
3007 error
= shmem_getpage_gfp(inode
, index
, &page
, SGP_CACHE
, gfp
, NULL
);
3009 page
= ERR_PTR(error
);
3015 * The tiny !SHMEM case uses ramfs without swap
3017 return read_cache_page_gfp(mapping
, index
, gfp
);
3020 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp
);