4 * Copyright (C) 1994-1999 Linus Torvalds
8 * This file handles the generic file mmap semantics used by
9 * most "normal" filesystems (but you don't /have/ to use this:
10 * the NFS filesystem used to do this differently, for example)
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/compiler.h>
16 #include <linux/uaccess.h>
17 #include <linux/aio.h>
18 #include <linux/capability.h>
19 #include <linux/kernel_stat.h>
21 #include <linux/swap.h>
22 #include <linux/mman.h>
23 #include <linux/pagemap.h>
24 #include <linux/file.h>
25 #include <linux/uio.h>
26 #include <linux/hash.h>
27 #include <linux/writeback.h>
28 #include <linux/backing-dev.h>
29 #include <linux/pagevec.h>
30 #include <linux/blkdev.h>
31 #include <linux/security.h>
32 #include <linux/syscalls.h>
33 #include <linux/cpuset.h>
34 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
35 #include <linux/memcontrol.h>
39 * FIXME: remove all knowledge of the buffer layer from the core VM
41 #include <linux/buffer_head.h> /* for generic_osync_inode */
47 * Shared mappings implemented 30.11.1994. It's not fully working yet,
50 * Shared mappings now work. 15.8.1995 Bruno.
52 * finished 'unifying' the page and buffer cache and SMP-threaded the
53 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
55 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
61 * ->i_mmap_lock (vmtruncate)
62 * ->private_lock (__free_pte->__set_page_dirty_buffers)
63 * ->swap_lock (exclusive_swap_page, others)
64 * ->mapping->tree_lock
67 * ->i_mmap_lock (truncate->unmap_mapping_range)
71 * ->page_table_lock or pte_lock (various, mainly in memory.c)
72 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
75 * ->lock_page (access_process_vm)
77 * ->i_mutex (generic_file_buffered_write)
78 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
81 * ->i_alloc_sem (various)
84 * ->sb_lock (fs/fs-writeback.c)
85 * ->mapping->tree_lock (__sync_single_inode)
88 * ->anon_vma.lock (vma_adjust)
91 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
93 * ->page_table_lock or pte_lock
94 * ->swap_lock (try_to_unmap_one)
95 * ->private_lock (try_to_unmap_one)
96 * ->tree_lock (try_to_unmap_one)
97 * ->zone.lru_lock (follow_page->mark_page_accessed)
98 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
99 * ->private_lock (page_remove_rmap->set_page_dirty)
100 * ->tree_lock (page_remove_rmap->set_page_dirty)
101 * ->inode_lock (page_remove_rmap->set_page_dirty)
102 * ->inode_lock (zap_pte_range->set_page_dirty)
103 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
106 * ->dcache_lock (proc_pid_lookup)
110 * Remove a page from the page cache and free it. Caller has to make
111 * sure the page is locked and that nobody else uses it - or that usage
112 * is safe. The caller must hold the mapping's tree_lock.
114 void __remove_from_page_cache(struct page
*page
)
116 struct address_space
*mapping
= page
->mapping
;
118 mem_cgroup_uncharge_cache_page(page
);
119 radix_tree_delete(&mapping
->page_tree
, page
->index
);
120 page
->mapping
= NULL
;
122 __dec_zone_page_state(page
, NR_FILE_PAGES
);
123 BUG_ON(page_mapped(page
));
126 * Some filesystems seem to re-dirty the page even after
127 * the VM has canceled the dirty bit (eg ext3 journaling).
129 * Fix it up by doing a final dirty accounting check after
130 * having removed the page entirely.
132 if (PageDirty(page
) && mapping_cap_account_dirty(mapping
)) {
133 dec_zone_page_state(page
, NR_FILE_DIRTY
);
134 dec_bdi_stat(mapping
->backing_dev_info
, BDI_RECLAIMABLE
);
138 void remove_from_page_cache(struct page
*page
)
140 struct address_space
*mapping
= page
->mapping
;
142 BUG_ON(!PageLocked(page
));
144 spin_lock_irq(&mapping
->tree_lock
);
145 __remove_from_page_cache(page
);
146 spin_unlock_irq(&mapping
->tree_lock
);
149 static int sync_page(void *word
)
151 struct address_space
*mapping
;
154 page
= container_of((unsigned long *)word
, struct page
, flags
);
157 * page_mapping() is being called without PG_locked held.
158 * Some knowledge of the state and use of the page is used to
159 * reduce the requirements down to a memory barrier.
160 * The danger here is of a stale page_mapping() return value
161 * indicating a struct address_space different from the one it's
162 * associated with when it is associated with one.
163 * After smp_mb(), it's either the correct page_mapping() for
164 * the page, or an old page_mapping() and the page's own
165 * page_mapping() has gone NULL.
166 * The ->sync_page() address_space operation must tolerate
167 * page_mapping() going NULL. By an amazing coincidence,
168 * this comes about because none of the users of the page
169 * in the ->sync_page() methods make essential use of the
170 * page_mapping(), merely passing the page down to the backing
171 * device's unplug functions when it's non-NULL, which in turn
172 * ignore it for all cases but swap, where only page_private(page) is
173 * of interest. When page_mapping() does go NULL, the entire
174 * call stack gracefully ignores the page and returns.
178 mapping
= page_mapping(page
);
179 if (mapping
&& mapping
->a_ops
&& mapping
->a_ops
->sync_page
)
180 mapping
->a_ops
->sync_page(page
);
185 static int sync_page_killable(void *word
)
188 return fatal_signal_pending(current
) ? -EINTR
: 0;
192 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
193 * @mapping: address space structure to write
194 * @start: offset in bytes where the range starts
195 * @end: offset in bytes where the range ends (inclusive)
196 * @sync_mode: enable synchronous operation
198 * Start writeback against all of a mapping's dirty pages that lie
199 * within the byte offsets <start, end> inclusive.
201 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
202 * opposed to a regular memory cleansing writeback. The difference between
203 * these two operations is that if a dirty page/buffer is encountered, it must
204 * be waited upon, and not just skipped over.
206 int __filemap_fdatawrite_range(struct address_space
*mapping
, loff_t start
,
207 loff_t end
, int sync_mode
)
210 struct writeback_control wbc
= {
211 .sync_mode
= sync_mode
,
212 .nr_to_write
= mapping
->nrpages
* 2,
213 .range_start
= start
,
217 if (!mapping_cap_writeback_dirty(mapping
))
220 ret
= do_writepages(mapping
, &wbc
);
224 static inline int __filemap_fdatawrite(struct address_space
*mapping
,
227 return __filemap_fdatawrite_range(mapping
, 0, LLONG_MAX
, sync_mode
);
230 int filemap_fdatawrite(struct address_space
*mapping
)
232 return __filemap_fdatawrite(mapping
, WB_SYNC_ALL
);
234 EXPORT_SYMBOL(filemap_fdatawrite
);
236 int filemap_fdatawrite_range(struct address_space
*mapping
, loff_t start
,
239 return __filemap_fdatawrite_range(mapping
, start
, end
, WB_SYNC_ALL
);
241 EXPORT_SYMBOL(filemap_fdatawrite_range
);
244 * filemap_flush - mostly a non-blocking flush
245 * @mapping: target address_space
247 * This is a mostly non-blocking flush. Not suitable for data-integrity
248 * purposes - I/O may not be started against all dirty pages.
250 int filemap_flush(struct address_space
*mapping
)
252 return __filemap_fdatawrite(mapping
, WB_SYNC_NONE
);
254 EXPORT_SYMBOL(filemap_flush
);
257 * wait_on_page_writeback_range - wait for writeback to complete
258 * @mapping: target address_space
259 * @start: beginning page index
260 * @end: ending page index
262 * Wait for writeback to complete against pages indexed by start->end
265 int wait_on_page_writeback_range(struct address_space
*mapping
,
266 pgoff_t start
, pgoff_t end
)
276 pagevec_init(&pvec
, 0);
278 while ((index
<= end
) &&
279 (nr_pages
= pagevec_lookup_tag(&pvec
, mapping
, &index
,
280 PAGECACHE_TAG_WRITEBACK
,
281 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
-1) + 1)) != 0) {
284 for (i
= 0; i
< nr_pages
; i
++) {
285 struct page
*page
= pvec
.pages
[i
];
287 /* until radix tree lookup accepts end_index */
288 if (page
->index
> end
)
291 wait_on_page_writeback(page
);
295 pagevec_release(&pvec
);
299 /* Check for outstanding write errors */
300 if (test_and_clear_bit(AS_ENOSPC
, &mapping
->flags
))
302 if (test_and_clear_bit(AS_EIO
, &mapping
->flags
))
309 * sync_page_range - write and wait on all pages in the passed range
310 * @inode: target inode
311 * @mapping: target address_space
312 * @pos: beginning offset in pages to write
313 * @count: number of bytes to write
315 * Write and wait upon all the pages in the passed range. This is a "data
316 * integrity" operation. It waits upon in-flight writeout before starting and
317 * waiting upon new writeout. If there was an IO error, return it.
319 * We need to re-take i_mutex during the generic_osync_inode list walk because
320 * it is otherwise livelockable.
322 int sync_page_range(struct inode
*inode
, struct address_space
*mapping
,
323 loff_t pos
, loff_t count
)
325 pgoff_t start
= pos
>> PAGE_CACHE_SHIFT
;
326 pgoff_t end
= (pos
+ count
- 1) >> PAGE_CACHE_SHIFT
;
329 if (!mapping_cap_writeback_dirty(mapping
) || !count
)
331 ret
= filemap_fdatawrite_range(mapping
, pos
, pos
+ count
- 1);
333 mutex_lock(&inode
->i_mutex
);
334 ret
= generic_osync_inode(inode
, mapping
, OSYNC_METADATA
);
335 mutex_unlock(&inode
->i_mutex
);
338 ret
= wait_on_page_writeback_range(mapping
, start
, end
);
341 EXPORT_SYMBOL(sync_page_range
);
344 * sync_page_range_nolock - write & wait on all pages in the passed range without locking
345 * @inode: target inode
346 * @mapping: target address_space
347 * @pos: beginning offset in pages to write
348 * @count: number of bytes to write
350 * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
351 * as it forces O_SYNC writers to different parts of the same file
352 * to be serialised right until io completion.
354 int sync_page_range_nolock(struct inode
*inode
, struct address_space
*mapping
,
355 loff_t pos
, loff_t count
)
357 pgoff_t start
= pos
>> PAGE_CACHE_SHIFT
;
358 pgoff_t end
= (pos
+ count
- 1) >> PAGE_CACHE_SHIFT
;
361 if (!mapping_cap_writeback_dirty(mapping
) || !count
)
363 ret
= filemap_fdatawrite_range(mapping
, pos
, pos
+ count
- 1);
365 ret
= generic_osync_inode(inode
, mapping
, OSYNC_METADATA
);
367 ret
= wait_on_page_writeback_range(mapping
, start
, end
);
370 EXPORT_SYMBOL(sync_page_range_nolock
);
373 * filemap_fdatawait - wait for all under-writeback pages to complete
374 * @mapping: address space structure to wait for
376 * Walk the list of under-writeback pages of the given address space
377 * and wait for all of them.
379 int filemap_fdatawait(struct address_space
*mapping
)
381 loff_t i_size
= i_size_read(mapping
->host
);
386 return wait_on_page_writeback_range(mapping
, 0,
387 (i_size
- 1) >> PAGE_CACHE_SHIFT
);
389 EXPORT_SYMBOL(filemap_fdatawait
);
391 int filemap_write_and_wait(struct address_space
*mapping
)
395 if (mapping
->nrpages
) {
396 err
= filemap_fdatawrite(mapping
);
398 * Even if the above returned error, the pages may be
399 * written partially (e.g. -ENOSPC), so we wait for it.
400 * But the -EIO is special case, it may indicate the worst
401 * thing (e.g. bug) happened, so we avoid waiting for it.
404 int err2
= filemap_fdatawait(mapping
);
411 EXPORT_SYMBOL(filemap_write_and_wait
);
414 * filemap_write_and_wait_range - write out & wait on a file range
415 * @mapping: the address_space for the pages
416 * @lstart: offset in bytes where the range starts
417 * @lend: offset in bytes where the range ends (inclusive)
419 * Write out and wait upon file offsets lstart->lend, inclusive.
421 * Note that `lend' is inclusive (describes the last byte to be written) so
422 * that this function can be used to write to the very end-of-file (end = -1).
424 int filemap_write_and_wait_range(struct address_space
*mapping
,
425 loff_t lstart
, loff_t lend
)
429 if (mapping
->nrpages
) {
430 err
= __filemap_fdatawrite_range(mapping
, lstart
, lend
,
432 /* See comment of filemap_write_and_wait() */
434 int err2
= wait_on_page_writeback_range(mapping
,
435 lstart
>> PAGE_CACHE_SHIFT
,
436 lend
>> PAGE_CACHE_SHIFT
);
445 * add_to_page_cache_locked - add a locked page to the pagecache
447 * @mapping: the page's address_space
448 * @offset: page index
449 * @gfp_mask: page allocation mode
451 * This function is used to add a page to the pagecache. It must be locked.
452 * This function does not add the page to the LRU. The caller must do that.
454 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
455 pgoff_t offset
, gfp_t gfp_mask
)
459 VM_BUG_ON(!PageLocked(page
));
461 error
= mem_cgroup_cache_charge(page
, current
->mm
,
462 gfp_mask
& ~__GFP_HIGHMEM
);
466 error
= radix_tree_preload(gfp_mask
& ~__GFP_HIGHMEM
);
468 page_cache_get(page
);
469 page
->mapping
= mapping
;
470 page
->index
= offset
;
472 spin_lock_irq(&mapping
->tree_lock
);
473 error
= radix_tree_insert(&mapping
->page_tree
, offset
, page
);
474 if (likely(!error
)) {
476 __inc_zone_page_state(page
, NR_FILE_PAGES
);
478 page
->mapping
= NULL
;
479 mem_cgroup_uncharge_cache_page(page
);
480 page_cache_release(page
);
483 spin_unlock_irq(&mapping
->tree_lock
);
484 radix_tree_preload_end();
486 mem_cgroup_uncharge_cache_page(page
);
490 EXPORT_SYMBOL(add_to_page_cache_locked
);
492 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
493 pgoff_t offset
, gfp_t gfp_mask
)
495 int ret
= add_to_page_cache(page
, mapping
, offset
, gfp_mask
);
502 struct page
*__page_cache_alloc(gfp_t gfp
)
504 if (cpuset_do_page_mem_spread()) {
505 int n
= cpuset_mem_spread_node();
506 return alloc_pages_node(n
, gfp
, 0);
508 return alloc_pages(gfp
, 0);
510 EXPORT_SYMBOL(__page_cache_alloc
);
513 static int __sleep_on_page_lock(void *word
)
520 * In order to wait for pages to become available there must be
521 * waitqueues associated with pages. By using a hash table of
522 * waitqueues where the bucket discipline is to maintain all
523 * waiters on the same queue and wake all when any of the pages
524 * become available, and for the woken contexts to check to be
525 * sure the appropriate page became available, this saves space
526 * at a cost of "thundering herd" phenomena during rare hash
529 static wait_queue_head_t
*page_waitqueue(struct page
*page
)
531 const struct zone
*zone
= page_zone(page
);
533 return &zone
->wait_table
[hash_ptr(page
, zone
->wait_table_bits
)];
536 static inline void wake_up_page(struct page
*page
, int bit
)
538 __wake_up_bit(page_waitqueue(page
), &page
->flags
, bit
);
541 void wait_on_page_bit(struct page
*page
, int bit_nr
)
543 DEFINE_WAIT_BIT(wait
, &page
->flags
, bit_nr
);
545 if (test_bit(bit_nr
, &page
->flags
))
546 __wait_on_bit(page_waitqueue(page
), &wait
, sync_page
,
547 TASK_UNINTERRUPTIBLE
);
549 EXPORT_SYMBOL(wait_on_page_bit
);
552 * unlock_page - unlock a locked page
555 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
556 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
557 * mechananism between PageLocked pages and PageWriteback pages is shared.
558 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
560 * The first mb is necessary to safely close the critical section opened by the
561 * test_and_set_bit() to lock the page; the second mb is necessary to enforce
562 * ordering between the clear_bit and the read of the waitqueue (to avoid SMP
563 * races with a parallel wait_on_page_locked()).
565 void unlock_page(struct page
*page
)
567 smp_mb__before_clear_bit();
568 if (!test_and_clear_bit(PG_locked
, &page
->flags
))
570 smp_mb__after_clear_bit();
571 wake_up_page(page
, PG_locked
);
573 EXPORT_SYMBOL(unlock_page
);
576 * end_page_writeback - end writeback against a page
579 void end_page_writeback(struct page
*page
)
581 if (TestClearPageReclaim(page
))
582 rotate_reclaimable_page(page
);
584 if (!test_clear_page_writeback(page
))
587 smp_mb__after_clear_bit();
588 wake_up_page(page
, PG_writeback
);
590 EXPORT_SYMBOL(end_page_writeback
);
593 * __lock_page - get a lock on the page, assuming we need to sleep to get it
594 * @page: the page to lock
596 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
597 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
598 * chances are that on the second loop, the block layer's plug list is empty,
599 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
601 void __lock_page(struct page
*page
)
603 DEFINE_WAIT_BIT(wait
, &page
->flags
, PG_locked
);
605 __wait_on_bit_lock(page_waitqueue(page
), &wait
, sync_page
,
606 TASK_UNINTERRUPTIBLE
);
608 EXPORT_SYMBOL(__lock_page
);
610 int __lock_page_killable(struct page
*page
)
612 DEFINE_WAIT_BIT(wait
, &page
->flags
, PG_locked
);
614 return __wait_on_bit_lock(page_waitqueue(page
), &wait
,
615 sync_page_killable
, TASK_KILLABLE
);
619 * __lock_page_nosync - get a lock on the page, without calling sync_page()
620 * @page: the page to lock
622 * Variant of lock_page that does not require the caller to hold a reference
623 * on the page's mapping.
625 void __lock_page_nosync(struct page
*page
)
627 DEFINE_WAIT_BIT(wait
, &page
->flags
, PG_locked
);
628 __wait_on_bit_lock(page_waitqueue(page
), &wait
, __sleep_on_page_lock
,
629 TASK_UNINTERRUPTIBLE
);
633 * find_get_page - find and get a page reference
634 * @mapping: the address_space to search
635 * @offset: the page index
637 * Is there a pagecache struct page at the given (mapping, offset) tuple?
638 * If yes, increment its refcount and return it; if no, return NULL.
640 struct page
*find_get_page(struct address_space
*mapping
, pgoff_t offset
)
648 pagep
= radix_tree_lookup_slot(&mapping
->page_tree
, offset
);
650 page
= radix_tree_deref_slot(pagep
);
651 if (unlikely(!page
|| page
== RADIX_TREE_RETRY
))
654 if (!page_cache_get_speculative(page
))
658 * Has the page moved?
659 * This is part of the lockless pagecache protocol. See
660 * include/linux/pagemap.h for details.
662 if (unlikely(page
!= *pagep
)) {
663 page_cache_release(page
);
671 EXPORT_SYMBOL(find_get_page
);
674 * find_lock_page - locate, pin and lock a pagecache page
675 * @mapping: the address_space to search
676 * @offset: the page index
678 * Locates the desired pagecache page, locks it, increments its reference
679 * count and returns its address.
681 * Returns zero if the page was not present. find_lock_page() may sleep.
683 struct page
*find_lock_page(struct address_space
*mapping
, pgoff_t offset
)
688 page
= find_get_page(mapping
, offset
);
691 /* Has the page been truncated? */
692 if (unlikely(page
->mapping
!= mapping
)) {
694 page_cache_release(page
);
697 VM_BUG_ON(page
->index
!= offset
);
701 EXPORT_SYMBOL(find_lock_page
);
704 * find_or_create_page - locate or add a pagecache page
705 * @mapping: the page's address_space
706 * @index: the page's index into the mapping
707 * @gfp_mask: page allocation mode
709 * Locates a page in the pagecache. If the page is not present, a new page
710 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
711 * LRU list. The returned page is locked and has its reference count
714 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
717 * find_or_create_page() returns the desired page's address, or zero on
720 struct page
*find_or_create_page(struct address_space
*mapping
,
721 pgoff_t index
, gfp_t gfp_mask
)
726 page
= find_lock_page(mapping
, index
);
728 page
= __page_cache_alloc(gfp_mask
);
731 err
= add_to_page_cache_lru(page
, mapping
, index
, gfp_mask
);
733 page_cache_release(page
);
741 EXPORT_SYMBOL(find_or_create_page
);
744 * find_get_pages - gang pagecache lookup
745 * @mapping: The address_space to search
746 * @start: The starting page index
747 * @nr_pages: The maximum number of pages
748 * @pages: Where the resulting pages are placed
750 * find_get_pages() will search for and return a group of up to
751 * @nr_pages pages in the mapping. The pages are placed at @pages.
752 * find_get_pages() takes a reference against the returned pages.
754 * The search returns a group of mapping-contiguous pages with ascending
755 * indexes. There may be holes in the indices due to not-present pages.
757 * find_get_pages() returns the number of pages which were found.
759 unsigned find_get_pages(struct address_space
*mapping
, pgoff_t start
,
760 unsigned int nr_pages
, struct page
**pages
)
764 unsigned int nr_found
;
768 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
769 (void ***)pages
, start
, nr_pages
);
771 for (i
= 0; i
< nr_found
; i
++) {
774 page
= radix_tree_deref_slot((void **)pages
[i
]);
778 * this can only trigger if nr_found == 1, making livelock
781 if (unlikely(page
== RADIX_TREE_RETRY
))
784 if (!page_cache_get_speculative(page
))
787 /* Has the page moved? */
788 if (unlikely(page
!= *((void **)pages
[i
]))) {
789 page_cache_release(page
);
801 * find_get_pages_contig - gang contiguous pagecache lookup
802 * @mapping: The address_space to search
803 * @index: The starting page index
804 * @nr_pages: The maximum number of pages
805 * @pages: Where the resulting pages are placed
807 * find_get_pages_contig() works exactly like find_get_pages(), except
808 * that the returned number of pages are guaranteed to be contiguous.
810 * find_get_pages_contig() returns the number of pages which were found.
812 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t index
,
813 unsigned int nr_pages
, struct page
**pages
)
817 unsigned int nr_found
;
821 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
822 (void ***)pages
, index
, nr_pages
);
824 for (i
= 0; i
< nr_found
; i
++) {
827 page
= radix_tree_deref_slot((void **)pages
[i
]);
831 * this can only trigger if nr_found == 1, making livelock
834 if (unlikely(page
== RADIX_TREE_RETRY
))
837 if (page
->mapping
== NULL
|| page
->index
!= index
)
840 if (!page_cache_get_speculative(page
))
843 /* Has the page moved? */
844 if (unlikely(page
!= *((void **)pages
[i
]))) {
845 page_cache_release(page
);
856 EXPORT_SYMBOL(find_get_pages_contig
);
859 * find_get_pages_tag - find and return pages that match @tag
860 * @mapping: the address_space to search
861 * @index: the starting page index
862 * @tag: the tag index
863 * @nr_pages: the maximum number of pages
864 * @pages: where the resulting pages are placed
866 * Like find_get_pages, except we only return pages which are tagged with
867 * @tag. We update @index to index the next page for the traversal.
869 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
870 int tag
, unsigned int nr_pages
, struct page
**pages
)
874 unsigned int nr_found
;
878 nr_found
= radix_tree_gang_lookup_tag_slot(&mapping
->page_tree
,
879 (void ***)pages
, *index
, nr_pages
, tag
);
881 for (i
= 0; i
< nr_found
; i
++) {
884 page
= radix_tree_deref_slot((void **)pages
[i
]);
888 * this can only trigger if nr_found == 1, making livelock
891 if (unlikely(page
== RADIX_TREE_RETRY
))
894 if (!page_cache_get_speculative(page
))
897 /* Has the page moved? */
898 if (unlikely(page
!= *((void **)pages
[i
]))) {
899 page_cache_release(page
);
909 *index
= pages
[ret
- 1]->index
+ 1;
913 EXPORT_SYMBOL(find_get_pages_tag
);
916 * grab_cache_page_nowait - returns locked page at given index in given cache
917 * @mapping: target address_space
918 * @index: the page index
920 * Same as grab_cache_page(), but do not wait if the page is unavailable.
921 * This is intended for speculative data generators, where the data can
922 * be regenerated if the page couldn't be grabbed. This routine should
923 * be safe to call while holding the lock for another page.
925 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
926 * and deadlock against the caller's locked page.
929 grab_cache_page_nowait(struct address_space
*mapping
, pgoff_t index
)
931 struct page
*page
= find_get_page(mapping
, index
);
934 if (trylock_page(page
))
936 page_cache_release(page
);
939 page
= __page_cache_alloc(mapping_gfp_mask(mapping
) & ~__GFP_FS
);
940 if (page
&& add_to_page_cache_lru(page
, mapping
, index
, GFP_KERNEL
)) {
941 page_cache_release(page
);
946 EXPORT_SYMBOL(grab_cache_page_nowait
);
949 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
950 * a _large_ part of the i/o request. Imagine the worst scenario:
952 * ---R__________________________________________B__________
953 * ^ reading here ^ bad block(assume 4k)
955 * read(R) => miss => readahead(R...B) => media error => frustrating retries
956 * => failing the whole request => read(R) => read(R+1) =>
957 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
958 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
959 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
961 * It is going insane. Fix it by quickly scaling down the readahead size.
963 static void shrink_readahead_size_eio(struct file
*filp
,
964 struct file_ra_state
*ra
)
973 * do_generic_file_read - generic file read routine
974 * @filp: the file to read
975 * @ppos: current file position
976 * @desc: read_descriptor
977 * @actor: read method
979 * This is a generic file read routine, and uses the
980 * mapping->a_ops->readpage() function for the actual low-level stuff.
982 * This is really ugly. But the goto's actually try to clarify some
983 * of the logic when it comes to error handling etc.
985 static void do_generic_file_read(struct file
*filp
, loff_t
*ppos
,
986 read_descriptor_t
*desc
, read_actor_t actor
)
988 struct address_space
*mapping
= filp
->f_mapping
;
989 struct inode
*inode
= mapping
->host
;
990 struct file_ra_state
*ra
= &filp
->f_ra
;
994 unsigned long offset
; /* offset into pagecache page */
995 unsigned int prev_offset
;
998 index
= *ppos
>> PAGE_CACHE_SHIFT
;
999 prev_index
= ra
->prev_pos
>> PAGE_CACHE_SHIFT
;
1000 prev_offset
= ra
->prev_pos
& (PAGE_CACHE_SIZE
-1);
1001 last_index
= (*ppos
+ desc
->count
+ PAGE_CACHE_SIZE
-1) >> PAGE_CACHE_SHIFT
;
1002 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1008 unsigned long nr
, ret
;
1012 page
= find_get_page(mapping
, index
);
1014 page_cache_sync_readahead(mapping
,
1016 index
, last_index
- index
);
1017 page
= find_get_page(mapping
, index
);
1018 if (unlikely(page
== NULL
))
1019 goto no_cached_page
;
1021 if (PageReadahead(page
)) {
1022 page_cache_async_readahead(mapping
,
1024 index
, last_index
- index
);
1026 if (!PageUptodate(page
)) {
1027 if (inode
->i_blkbits
== PAGE_CACHE_SHIFT
||
1028 !mapping
->a_ops
->is_partially_uptodate
)
1029 goto page_not_up_to_date
;
1030 if (!trylock_page(page
))
1031 goto page_not_up_to_date
;
1032 if (!mapping
->a_ops
->is_partially_uptodate(page
,
1034 goto page_not_up_to_date_locked
;
1039 * i_size must be checked after we know the page is Uptodate.
1041 * Checking i_size after the check allows us to calculate
1042 * the correct value for "nr", which means the zero-filled
1043 * part of the page is not copied back to userspace (unless
1044 * another truncate extends the file - this is desired though).
1047 isize
= i_size_read(inode
);
1048 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1049 if (unlikely(!isize
|| index
> end_index
)) {
1050 page_cache_release(page
);
1054 /* nr is the maximum number of bytes to copy from this page */
1055 nr
= PAGE_CACHE_SIZE
;
1056 if (index
== end_index
) {
1057 nr
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1059 page_cache_release(page
);
1065 /* If users can be writing to this page using arbitrary
1066 * virtual addresses, take care about potential aliasing
1067 * before reading the page on the kernel side.
1069 if (mapping_writably_mapped(mapping
))
1070 flush_dcache_page(page
);
1073 * When a sequential read accesses a page several times,
1074 * only mark it as accessed the first time.
1076 if (prev_index
!= index
|| offset
!= prev_offset
)
1077 mark_page_accessed(page
);
1081 * Ok, we have the page, and it's up-to-date, so
1082 * now we can copy it to user space...
1084 * The actor routine returns how many bytes were actually used..
1085 * NOTE! This may not be the same as how much of a user buffer
1086 * we filled up (we may be padding etc), so we can only update
1087 * "pos" here (the actor routine has to update the user buffer
1088 * pointers and the remaining count).
1090 ret
= actor(desc
, page
, offset
, nr
);
1092 index
+= offset
>> PAGE_CACHE_SHIFT
;
1093 offset
&= ~PAGE_CACHE_MASK
;
1094 prev_offset
= offset
;
1096 page_cache_release(page
);
1097 if (ret
== nr
&& desc
->count
)
1101 page_not_up_to_date
:
1102 /* Get exclusive access to the page ... */
1103 error
= lock_page_killable(page
);
1104 if (unlikely(error
))
1105 goto readpage_error
;
1107 page_not_up_to_date_locked
:
1108 /* Did it get truncated before we got the lock? */
1109 if (!page
->mapping
) {
1111 page_cache_release(page
);
1115 /* Did somebody else fill it already? */
1116 if (PageUptodate(page
)) {
1122 /* Start the actual read. The read will unlock the page. */
1123 error
= mapping
->a_ops
->readpage(filp
, page
);
1125 if (unlikely(error
)) {
1126 if (error
== AOP_TRUNCATED_PAGE
) {
1127 page_cache_release(page
);
1130 goto readpage_error
;
1133 if (!PageUptodate(page
)) {
1134 error
= lock_page_killable(page
);
1135 if (unlikely(error
))
1136 goto readpage_error
;
1137 if (!PageUptodate(page
)) {
1138 if (page
->mapping
== NULL
) {
1140 * invalidate_inode_pages got it
1143 page_cache_release(page
);
1147 shrink_readahead_size_eio(filp
, ra
);
1149 goto readpage_error
;
1157 /* UHHUH! A synchronous read error occurred. Report it */
1158 desc
->error
= error
;
1159 page_cache_release(page
);
1164 * Ok, it wasn't cached, so we need to create a new
1167 page
= page_cache_alloc_cold(mapping
);
1169 desc
->error
= -ENOMEM
;
1172 error
= add_to_page_cache_lru(page
, mapping
,
1175 page_cache_release(page
);
1176 if (error
== -EEXIST
)
1178 desc
->error
= error
;
1185 ra
->prev_pos
= prev_index
;
1186 ra
->prev_pos
<<= PAGE_CACHE_SHIFT
;
1187 ra
->prev_pos
|= prev_offset
;
1189 *ppos
= ((loff_t
)index
<< PAGE_CACHE_SHIFT
) + offset
;
1191 file_accessed(filp
);
1194 int file_read_actor(read_descriptor_t
*desc
, struct page
*page
,
1195 unsigned long offset
, unsigned long size
)
1198 unsigned long left
, count
= desc
->count
;
1204 * Faults on the destination of a read are common, so do it before
1207 if (!fault_in_pages_writeable(desc
->arg
.buf
, size
)) {
1208 kaddr
= kmap_atomic(page
, KM_USER0
);
1209 left
= __copy_to_user_inatomic(desc
->arg
.buf
,
1210 kaddr
+ offset
, size
);
1211 kunmap_atomic(kaddr
, KM_USER0
);
1216 /* Do it the slow way */
1218 left
= __copy_to_user(desc
->arg
.buf
, kaddr
+ offset
, size
);
1223 desc
->error
= -EFAULT
;
1226 desc
->count
= count
- size
;
1227 desc
->written
+= size
;
1228 desc
->arg
.buf
+= size
;
1233 * Performs necessary checks before doing a write
1234 * @iov: io vector request
1235 * @nr_segs: number of segments in the iovec
1236 * @count: number of bytes to write
1237 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1239 * Adjust number of segments and amount of bytes to write (nr_segs should be
1240 * properly initialized first). Returns appropriate error code that caller
1241 * should return or zero in case that write should be allowed.
1243 int generic_segment_checks(const struct iovec
*iov
,
1244 unsigned long *nr_segs
, size_t *count
, int access_flags
)
1248 for (seg
= 0; seg
< *nr_segs
; seg
++) {
1249 const struct iovec
*iv
= &iov
[seg
];
1252 * If any segment has a negative length, or the cumulative
1253 * length ever wraps negative then return -EINVAL.
1256 if (unlikely((ssize_t
)(cnt
|iv
->iov_len
) < 0))
1258 if (access_ok(access_flags
, iv
->iov_base
, iv
->iov_len
))
1263 cnt
-= iv
->iov_len
; /* This segment is no good */
1269 EXPORT_SYMBOL(generic_segment_checks
);
1272 * generic_file_aio_read - generic filesystem read routine
1273 * @iocb: kernel I/O control block
1274 * @iov: io vector request
1275 * @nr_segs: number of segments in the iovec
1276 * @pos: current file position
1278 * This is the "read()" routine for all filesystems
1279 * that can use the page cache directly.
1282 generic_file_aio_read(struct kiocb
*iocb
, const struct iovec
*iov
,
1283 unsigned long nr_segs
, loff_t pos
)
1285 struct file
*filp
= iocb
->ki_filp
;
1289 loff_t
*ppos
= &iocb
->ki_pos
;
1292 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1296 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1297 if (filp
->f_flags
& O_DIRECT
) {
1299 struct address_space
*mapping
;
1300 struct inode
*inode
;
1302 mapping
= filp
->f_mapping
;
1303 inode
= mapping
->host
;
1305 goto out
; /* skip atime */
1306 size
= i_size_read(inode
);
1308 retval
= filemap_write_and_wait(mapping
);
1310 retval
= mapping
->a_ops
->direct_IO(READ
, iocb
,
1314 *ppos
= pos
+ retval
;
1316 file_accessed(filp
);
1322 for (seg
= 0; seg
< nr_segs
; seg
++) {
1323 read_descriptor_t desc
;
1326 desc
.arg
.buf
= iov
[seg
].iov_base
;
1327 desc
.count
= iov
[seg
].iov_len
;
1328 if (desc
.count
== 0)
1331 do_generic_file_read(filp
, ppos
, &desc
, file_read_actor
);
1332 retval
+= desc
.written
;
1334 retval
= retval
?: desc
.error
;
1343 EXPORT_SYMBOL(generic_file_aio_read
);
1346 do_readahead(struct address_space
*mapping
, struct file
*filp
,
1347 pgoff_t index
, unsigned long nr
)
1349 if (!mapping
|| !mapping
->a_ops
|| !mapping
->a_ops
->readpage
)
1352 force_page_cache_readahead(mapping
, filp
, index
,
1353 max_sane_readahead(nr
));
1357 asmlinkage ssize_t
sys_readahead(int fd
, loff_t offset
, size_t count
)
1365 if (file
->f_mode
& FMODE_READ
) {
1366 struct address_space
*mapping
= file
->f_mapping
;
1367 pgoff_t start
= offset
>> PAGE_CACHE_SHIFT
;
1368 pgoff_t end
= (offset
+ count
- 1) >> PAGE_CACHE_SHIFT
;
1369 unsigned long len
= end
- start
+ 1;
1370 ret
= do_readahead(mapping
, file
, start
, len
);
1379 * page_cache_read - adds requested page to the page cache if not already there
1380 * @file: file to read
1381 * @offset: page index
1383 * This adds the requested page to the page cache if it isn't already there,
1384 * and schedules an I/O to read in its contents from disk.
1386 static int page_cache_read(struct file
*file
, pgoff_t offset
)
1388 struct address_space
*mapping
= file
->f_mapping
;
1393 page
= page_cache_alloc_cold(mapping
);
1397 ret
= add_to_page_cache_lru(page
, mapping
, offset
, GFP_KERNEL
);
1399 ret
= mapping
->a_ops
->readpage(file
, page
);
1400 else if (ret
== -EEXIST
)
1401 ret
= 0; /* losing race to add is OK */
1403 page_cache_release(page
);
1405 } while (ret
== AOP_TRUNCATED_PAGE
);
1410 #define MMAP_LOTSAMISS (100)
1413 * filemap_fault - read in file data for page fault handling
1414 * @vma: vma in which the fault was taken
1415 * @vmf: struct vm_fault containing details of the fault
1417 * filemap_fault() is invoked via the vma operations vector for a
1418 * mapped memory region to read in file data during a page fault.
1420 * The goto's are kind of ugly, but this streamlines the normal case of having
1421 * it in the page cache, and handles the special cases reasonably without
1422 * having a lot of duplicated code.
1424 int filemap_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1427 struct file
*file
= vma
->vm_file
;
1428 struct address_space
*mapping
= file
->f_mapping
;
1429 struct file_ra_state
*ra
= &file
->f_ra
;
1430 struct inode
*inode
= mapping
->host
;
1433 int did_readaround
= 0;
1436 size
= (i_size_read(inode
) + PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1437 if (vmf
->pgoff
>= size
)
1438 return VM_FAULT_SIGBUS
;
1440 /* If we don't want any read-ahead, don't bother */
1441 if (VM_RandomReadHint(vma
))
1442 goto no_cached_page
;
1445 * Do we have something in the page cache already?
1448 page
= find_lock_page(mapping
, vmf
->pgoff
);
1450 * For sequential accesses, we use the generic readahead logic.
1452 if (VM_SequentialReadHint(vma
)) {
1454 page_cache_sync_readahead(mapping
, ra
, file
,
1456 page
= find_lock_page(mapping
, vmf
->pgoff
);
1458 goto no_cached_page
;
1460 if (PageReadahead(page
)) {
1461 page_cache_async_readahead(mapping
, ra
, file
, page
,
1467 unsigned long ra_pages
;
1472 * Do we miss much more than hit in this file? If so,
1473 * stop bothering with read-ahead. It will only hurt.
1475 if (ra
->mmap_miss
> MMAP_LOTSAMISS
)
1476 goto no_cached_page
;
1479 * To keep the pgmajfault counter straight, we need to
1480 * check did_readaround, as this is an inner loop.
1482 if (!did_readaround
) {
1483 ret
= VM_FAULT_MAJOR
;
1484 count_vm_event(PGMAJFAULT
);
1487 ra_pages
= max_sane_readahead(file
->f_ra
.ra_pages
);
1491 if (vmf
->pgoff
> ra_pages
/ 2)
1492 start
= vmf
->pgoff
- ra_pages
/ 2;
1493 do_page_cache_readahead(mapping
, file
, start
, ra_pages
);
1495 page
= find_lock_page(mapping
, vmf
->pgoff
);
1497 goto no_cached_page
;
1500 if (!did_readaround
)
1504 * We have a locked page in the page cache, now we need to check
1505 * that it's up-to-date. If not, it is going to be due to an error.
1507 if (unlikely(!PageUptodate(page
)))
1508 goto page_not_uptodate
;
1510 /* Must recheck i_size under page lock */
1511 size
= (i_size_read(inode
) + PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1512 if (unlikely(vmf
->pgoff
>= size
)) {
1514 page_cache_release(page
);
1515 return VM_FAULT_SIGBUS
;
1519 * Found the page and have a reference on it.
1521 mark_page_accessed(page
);
1522 ra
->prev_pos
= (loff_t
)page
->index
<< PAGE_CACHE_SHIFT
;
1524 return ret
| VM_FAULT_LOCKED
;
1528 * We're only likely to ever get here if MADV_RANDOM is in
1531 error
= page_cache_read(file
, vmf
->pgoff
);
1534 * The page we want has now been added to the page cache.
1535 * In the unlikely event that someone removed it in the
1536 * meantime, we'll just come back here and read it again.
1542 * An error return from page_cache_read can result if the
1543 * system is low on memory, or a problem occurs while trying
1546 if (error
== -ENOMEM
)
1547 return VM_FAULT_OOM
;
1548 return VM_FAULT_SIGBUS
;
1552 if (!did_readaround
) {
1553 ret
= VM_FAULT_MAJOR
;
1554 count_vm_event(PGMAJFAULT
);
1558 * Umm, take care of errors if the page isn't up-to-date.
1559 * Try to re-read it _once_. We do this synchronously,
1560 * because there really aren't any performance issues here
1561 * and we need to check for errors.
1563 ClearPageError(page
);
1564 error
= mapping
->a_ops
->readpage(file
, page
);
1566 wait_on_page_locked(page
);
1567 if (!PageUptodate(page
))
1570 page_cache_release(page
);
1572 if (!error
|| error
== AOP_TRUNCATED_PAGE
)
1575 /* Things didn't work out. Return zero to tell the mm layer so. */
1576 shrink_readahead_size_eio(file
, ra
);
1577 return VM_FAULT_SIGBUS
;
1579 EXPORT_SYMBOL(filemap_fault
);
1581 struct vm_operations_struct generic_file_vm_ops
= {
1582 .fault
= filemap_fault
,
1585 /* This is used for a general mmap of a disk file */
1587 int generic_file_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1589 struct address_space
*mapping
= file
->f_mapping
;
1591 if (!mapping
->a_ops
->readpage
)
1593 file_accessed(file
);
1594 vma
->vm_ops
= &generic_file_vm_ops
;
1595 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1600 * This is for filesystems which do not implement ->writepage.
1602 int generic_file_readonly_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1604 if ((vma
->vm_flags
& VM_SHARED
) && (vma
->vm_flags
& VM_MAYWRITE
))
1606 return generic_file_mmap(file
, vma
);
1609 int generic_file_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1613 int generic_file_readonly_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1617 #endif /* CONFIG_MMU */
1619 EXPORT_SYMBOL(generic_file_mmap
);
1620 EXPORT_SYMBOL(generic_file_readonly_mmap
);
1622 static struct page
*__read_cache_page(struct address_space
*mapping
,
1624 int (*filler
)(void *,struct page
*),
1630 page
= find_get_page(mapping
, index
);
1632 page
= page_cache_alloc_cold(mapping
);
1634 return ERR_PTR(-ENOMEM
);
1635 err
= add_to_page_cache_lru(page
, mapping
, index
, GFP_KERNEL
);
1636 if (unlikely(err
)) {
1637 page_cache_release(page
);
1640 /* Presumably ENOMEM for radix tree node */
1641 return ERR_PTR(err
);
1643 err
= filler(data
, page
);
1645 page_cache_release(page
);
1646 page
= ERR_PTR(err
);
1653 * read_cache_page_async - read into page cache, fill it if needed
1654 * @mapping: the page's address_space
1655 * @index: the page index
1656 * @filler: function to perform the read
1657 * @data: destination for read data
1659 * Same as read_cache_page, but don't wait for page to become unlocked
1660 * after submitting it to the filler.
1662 * Read into the page cache. If a page already exists, and PageUptodate() is
1663 * not set, try to fill the page but don't wait for it to become unlocked.
1665 * If the page does not get brought uptodate, return -EIO.
1667 struct page
*read_cache_page_async(struct address_space
*mapping
,
1669 int (*filler
)(void *,struct page
*),
1676 page
= __read_cache_page(mapping
, index
, filler
, data
);
1679 if (PageUptodate(page
))
1683 if (!page
->mapping
) {
1685 page_cache_release(page
);
1688 if (PageUptodate(page
)) {
1692 err
= filler(data
, page
);
1694 page_cache_release(page
);
1695 return ERR_PTR(err
);
1698 mark_page_accessed(page
);
1701 EXPORT_SYMBOL(read_cache_page_async
);
1704 * read_cache_page - read into page cache, fill it if needed
1705 * @mapping: the page's address_space
1706 * @index: the page index
1707 * @filler: function to perform the read
1708 * @data: destination for read data
1710 * Read into the page cache. If a page already exists, and PageUptodate() is
1711 * not set, try to fill the page then wait for it to become unlocked.
1713 * If the page does not get brought uptodate, return -EIO.
1715 struct page
*read_cache_page(struct address_space
*mapping
,
1717 int (*filler
)(void *,struct page
*),
1722 page
= read_cache_page_async(mapping
, index
, filler
, data
);
1725 wait_on_page_locked(page
);
1726 if (!PageUptodate(page
)) {
1727 page_cache_release(page
);
1728 page
= ERR_PTR(-EIO
);
1733 EXPORT_SYMBOL(read_cache_page
);
1736 * The logic we want is
1738 * if suid or (sgid and xgrp)
1741 int should_remove_suid(struct dentry
*dentry
)
1743 mode_t mode
= dentry
->d_inode
->i_mode
;
1746 /* suid always must be killed */
1747 if (unlikely(mode
& S_ISUID
))
1748 kill
= ATTR_KILL_SUID
;
1751 * sgid without any exec bits is just a mandatory locking mark; leave
1752 * it alone. If some exec bits are set, it's a real sgid; kill it.
1754 if (unlikely((mode
& S_ISGID
) && (mode
& S_IXGRP
)))
1755 kill
|= ATTR_KILL_SGID
;
1757 if (unlikely(kill
&& !capable(CAP_FSETID
)))
1762 EXPORT_SYMBOL(should_remove_suid
);
1764 static int __remove_suid(struct dentry
*dentry
, int kill
)
1766 struct iattr newattrs
;
1768 newattrs
.ia_valid
= ATTR_FORCE
| kill
;
1769 return notify_change(dentry
, &newattrs
);
1772 int file_remove_suid(struct file
*file
)
1774 struct dentry
*dentry
= file
->f_path
.dentry
;
1775 int killsuid
= should_remove_suid(dentry
);
1776 int killpriv
= security_inode_need_killpriv(dentry
);
1782 error
= security_inode_killpriv(dentry
);
1783 if (!error
&& killsuid
)
1784 error
= __remove_suid(dentry
, killsuid
);
1788 EXPORT_SYMBOL(file_remove_suid
);
1790 static size_t __iovec_copy_from_user_inatomic(char *vaddr
,
1791 const struct iovec
*iov
, size_t base
, size_t bytes
)
1793 size_t copied
= 0, left
= 0;
1796 char __user
*buf
= iov
->iov_base
+ base
;
1797 int copy
= min(bytes
, iov
->iov_len
- base
);
1800 left
= __copy_from_user_inatomic_nocache(vaddr
, buf
, copy
);
1809 return copied
- left
;
1813 * Copy as much as we can into the page and return the number of bytes which
1814 * were sucessfully copied. If a fault is encountered then return the number of
1815 * bytes which were copied.
1817 size_t iov_iter_copy_from_user_atomic(struct page
*page
,
1818 struct iov_iter
*i
, unsigned long offset
, size_t bytes
)
1823 BUG_ON(!in_atomic());
1824 kaddr
= kmap_atomic(page
, KM_USER0
);
1825 if (likely(i
->nr_segs
== 1)) {
1827 char __user
*buf
= i
->iov
->iov_base
+ i
->iov_offset
;
1828 left
= __copy_from_user_inatomic_nocache(kaddr
+ offset
,
1830 copied
= bytes
- left
;
1832 copied
= __iovec_copy_from_user_inatomic(kaddr
+ offset
,
1833 i
->iov
, i
->iov_offset
, bytes
);
1835 kunmap_atomic(kaddr
, KM_USER0
);
1839 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic
);
1842 * This has the same sideeffects and return value as
1843 * iov_iter_copy_from_user_atomic().
1844 * The difference is that it attempts to resolve faults.
1845 * Page must not be locked.
1847 size_t iov_iter_copy_from_user(struct page
*page
,
1848 struct iov_iter
*i
, unsigned long offset
, size_t bytes
)
1854 if (likely(i
->nr_segs
== 1)) {
1856 char __user
*buf
= i
->iov
->iov_base
+ i
->iov_offset
;
1857 left
= __copy_from_user_nocache(kaddr
+ offset
, buf
, bytes
);
1858 copied
= bytes
- left
;
1860 copied
= __iovec_copy_from_user_inatomic(kaddr
+ offset
,
1861 i
->iov
, i
->iov_offset
, bytes
);
1866 EXPORT_SYMBOL(iov_iter_copy_from_user
);
1868 void iov_iter_advance(struct iov_iter
*i
, size_t bytes
)
1870 BUG_ON(i
->count
< bytes
);
1872 if (likely(i
->nr_segs
== 1)) {
1873 i
->iov_offset
+= bytes
;
1876 const struct iovec
*iov
= i
->iov
;
1877 size_t base
= i
->iov_offset
;
1880 * The !iov->iov_len check ensures we skip over unlikely
1881 * zero-length segments (without overruning the iovec).
1883 while (bytes
|| unlikely(i
->count
&& !iov
->iov_len
)) {
1886 copy
= min(bytes
, iov
->iov_len
- base
);
1887 BUG_ON(!i
->count
|| i
->count
< copy
);
1891 if (iov
->iov_len
== base
) {
1897 i
->iov_offset
= base
;
1900 EXPORT_SYMBOL(iov_iter_advance
);
1903 * Fault in the first iovec of the given iov_iter, to a maximum length
1904 * of bytes. Returns 0 on success, or non-zero if the memory could not be
1905 * accessed (ie. because it is an invalid address).
1907 * writev-intensive code may want this to prefault several iovecs -- that
1908 * would be possible (callers must not rely on the fact that _only_ the
1909 * first iovec will be faulted with the current implementation).
1911 int iov_iter_fault_in_readable(struct iov_iter
*i
, size_t bytes
)
1913 char __user
*buf
= i
->iov
->iov_base
+ i
->iov_offset
;
1914 bytes
= min(bytes
, i
->iov
->iov_len
- i
->iov_offset
);
1915 return fault_in_pages_readable(buf
, bytes
);
1917 EXPORT_SYMBOL(iov_iter_fault_in_readable
);
1920 * Return the count of just the current iov_iter segment.
1922 size_t iov_iter_single_seg_count(struct iov_iter
*i
)
1924 const struct iovec
*iov
= i
->iov
;
1925 if (i
->nr_segs
== 1)
1928 return min(i
->count
, iov
->iov_len
- i
->iov_offset
);
1930 EXPORT_SYMBOL(iov_iter_single_seg_count
);
1933 * Performs necessary checks before doing a write
1935 * Can adjust writing position or amount of bytes to write.
1936 * Returns appropriate error code that caller should return or
1937 * zero in case that write should be allowed.
1939 inline int generic_write_checks(struct file
*file
, loff_t
*pos
, size_t *count
, int isblk
)
1941 struct inode
*inode
= file
->f_mapping
->host
;
1942 unsigned long limit
= current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
;
1944 if (unlikely(*pos
< 0))
1948 /* FIXME: this is for backwards compatibility with 2.4 */
1949 if (file
->f_flags
& O_APPEND
)
1950 *pos
= i_size_read(inode
);
1952 if (limit
!= RLIM_INFINITY
) {
1953 if (*pos
>= limit
) {
1954 send_sig(SIGXFSZ
, current
, 0);
1957 if (*count
> limit
- (typeof(limit
))*pos
) {
1958 *count
= limit
- (typeof(limit
))*pos
;
1966 if (unlikely(*pos
+ *count
> MAX_NON_LFS
&&
1967 !(file
->f_flags
& O_LARGEFILE
))) {
1968 if (*pos
>= MAX_NON_LFS
) {
1971 if (*count
> MAX_NON_LFS
- (unsigned long)*pos
) {
1972 *count
= MAX_NON_LFS
- (unsigned long)*pos
;
1977 * Are we about to exceed the fs block limit ?
1979 * If we have written data it becomes a short write. If we have
1980 * exceeded without writing data we send a signal and return EFBIG.
1981 * Linus frestrict idea will clean these up nicely..
1983 if (likely(!isblk
)) {
1984 if (unlikely(*pos
>= inode
->i_sb
->s_maxbytes
)) {
1985 if (*count
|| *pos
> inode
->i_sb
->s_maxbytes
) {
1988 /* zero-length writes at ->s_maxbytes are OK */
1991 if (unlikely(*pos
+ *count
> inode
->i_sb
->s_maxbytes
))
1992 *count
= inode
->i_sb
->s_maxbytes
- *pos
;
1996 if (bdev_read_only(I_BDEV(inode
)))
1998 isize
= i_size_read(inode
);
1999 if (*pos
>= isize
) {
2000 if (*count
|| *pos
> isize
)
2004 if (*pos
+ *count
> isize
)
2005 *count
= isize
- *pos
;
2012 EXPORT_SYMBOL(generic_write_checks
);
2014 int pagecache_write_begin(struct file
*file
, struct address_space
*mapping
,
2015 loff_t pos
, unsigned len
, unsigned flags
,
2016 struct page
**pagep
, void **fsdata
)
2018 const struct address_space_operations
*aops
= mapping
->a_ops
;
2020 if (aops
->write_begin
) {
2021 return aops
->write_begin(file
, mapping
, pos
, len
, flags
,
2025 pgoff_t index
= pos
>> PAGE_CACHE_SHIFT
;
2026 unsigned offset
= pos
& (PAGE_CACHE_SIZE
- 1);
2027 struct inode
*inode
= mapping
->host
;
2030 page
= __grab_cache_page(mapping
, index
);
2035 if (flags
& AOP_FLAG_UNINTERRUPTIBLE
&& !PageUptodate(page
)) {
2037 * There is no way to resolve a short write situation
2038 * for a !Uptodate page (except by double copying in
2039 * the caller done by generic_perform_write_2copy).
2041 * Instead, we have to bring it uptodate here.
2043 ret
= aops
->readpage(file
, page
);
2044 page_cache_release(page
);
2046 if (ret
== AOP_TRUNCATED_PAGE
)
2053 ret
= aops
->prepare_write(file
, page
, offset
, offset
+len
);
2056 page_cache_release(page
);
2057 if (pos
+ len
> inode
->i_size
)
2058 vmtruncate(inode
, inode
->i_size
);
2063 EXPORT_SYMBOL(pagecache_write_begin
);
2065 int pagecache_write_end(struct file
*file
, struct address_space
*mapping
,
2066 loff_t pos
, unsigned len
, unsigned copied
,
2067 struct page
*page
, void *fsdata
)
2069 const struct address_space_operations
*aops
= mapping
->a_ops
;
2072 if (aops
->write_end
) {
2073 mark_page_accessed(page
);
2074 ret
= aops
->write_end(file
, mapping
, pos
, len
, copied
,
2077 unsigned offset
= pos
& (PAGE_CACHE_SIZE
- 1);
2078 struct inode
*inode
= mapping
->host
;
2080 flush_dcache_page(page
);
2081 ret
= aops
->commit_write(file
, page
, offset
, offset
+len
);
2083 mark_page_accessed(page
);
2084 page_cache_release(page
);
2087 if (pos
+ len
> inode
->i_size
)
2088 vmtruncate(inode
, inode
->i_size
);
2090 ret
= min_t(size_t, copied
, ret
);
2097 EXPORT_SYMBOL(pagecache_write_end
);
2100 generic_file_direct_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2101 unsigned long *nr_segs
, loff_t pos
, loff_t
*ppos
,
2102 size_t count
, size_t ocount
)
2104 struct file
*file
= iocb
->ki_filp
;
2105 struct address_space
*mapping
= file
->f_mapping
;
2106 struct inode
*inode
= mapping
->host
;
2111 if (count
!= ocount
)
2112 *nr_segs
= iov_shorten((struct iovec
*)iov
, *nr_segs
, count
);
2115 * Unmap all mmappings of the file up-front.
2117 * This will cause any pte dirty bits to be propagated into the
2118 * pageframes for the subsequent filemap_write_and_wait().
2120 write_len
= iov_length(iov
, *nr_segs
);
2121 end
= (pos
+ write_len
- 1) >> PAGE_CACHE_SHIFT
;
2122 if (mapping_mapped(mapping
))
2123 unmap_mapping_range(mapping
, pos
, write_len
, 0);
2125 written
= filemap_write_and_wait(mapping
);
2130 * After a write we want buffered reads to be sure to go to disk to get
2131 * the new data. We invalidate clean cached page from the region we're
2132 * about to write. We do this *before* the write so that we can return
2133 * without clobbering -EIOCBQUEUED from ->direct_IO().
2135 if (mapping
->nrpages
) {
2136 written
= invalidate_inode_pages2_range(mapping
,
2137 pos
>> PAGE_CACHE_SHIFT
, end
);
2139 * If a page can not be invalidated, return 0 to fall back
2140 * to buffered write.
2143 if (written
== -EBUSY
)
2149 written
= mapping
->a_ops
->direct_IO(WRITE
, iocb
, iov
, pos
, *nr_segs
);
2152 * Finally, try again to invalidate clean pages which might have been
2153 * cached by non-direct readahead, or faulted in by get_user_pages()
2154 * if the source of the write was an mmap'ed region of the file
2155 * we're writing. Either one is a pretty crazy thing to do,
2156 * so we don't support it 100%. If this invalidation
2157 * fails, tough, the write still worked...
2159 if (mapping
->nrpages
) {
2160 invalidate_inode_pages2_range(mapping
,
2161 pos
>> PAGE_CACHE_SHIFT
, end
);
2165 loff_t end
= pos
+ written
;
2166 if (end
> i_size_read(inode
) && !S_ISBLK(inode
->i_mode
)) {
2167 i_size_write(inode
, end
);
2168 mark_inode_dirty(inode
);
2174 * Sync the fs metadata but not the minor inode changes and
2175 * of course not the data as we did direct DMA for the IO.
2176 * i_mutex is held, which protects generic_osync_inode() from
2177 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
2180 if ((written
>= 0 || written
== -EIOCBQUEUED
) &&
2181 ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2182 int err
= generic_osync_inode(inode
, mapping
, OSYNC_METADATA
);
2188 EXPORT_SYMBOL(generic_file_direct_write
);
2191 * Find or create a page at the given pagecache position. Return the locked
2192 * page. This function is specifically for buffered writes.
2194 struct page
*__grab_cache_page(struct address_space
*mapping
, pgoff_t index
)
2199 page
= find_lock_page(mapping
, index
);
2203 page
= page_cache_alloc(mapping
);
2206 status
= add_to_page_cache_lru(page
, mapping
, index
, GFP_KERNEL
);
2207 if (unlikely(status
)) {
2208 page_cache_release(page
);
2209 if (status
== -EEXIST
)
2215 EXPORT_SYMBOL(__grab_cache_page
);
2217 static ssize_t
generic_perform_write_2copy(struct file
*file
,
2218 struct iov_iter
*i
, loff_t pos
)
2220 struct address_space
*mapping
= file
->f_mapping
;
2221 const struct address_space_operations
*a_ops
= mapping
->a_ops
;
2222 struct inode
*inode
= mapping
->host
;
2224 ssize_t written
= 0;
2227 struct page
*src_page
;
2229 pgoff_t index
; /* Pagecache index for current page */
2230 unsigned long offset
; /* Offset into pagecache page */
2231 unsigned long bytes
; /* Bytes to write to page */
2232 size_t copied
; /* Bytes copied from user */
2234 offset
= (pos
& (PAGE_CACHE_SIZE
- 1));
2235 index
= pos
>> PAGE_CACHE_SHIFT
;
2236 bytes
= min_t(unsigned long, PAGE_CACHE_SIZE
- offset
,
2240 * a non-NULL src_page indicates that we're doing the
2241 * copy via get_user_pages and kmap.
2246 * Bring in the user page that we will copy from _first_.
2247 * Otherwise there's a nasty deadlock on copying from the
2248 * same page as we're writing to, without it being marked
2251 * Not only is this an optimisation, but it is also required
2252 * to check that the address is actually valid, when atomic
2253 * usercopies are used, below.
2255 if (unlikely(iov_iter_fault_in_readable(i
, bytes
))) {
2260 page
= __grab_cache_page(mapping
, index
);
2267 * non-uptodate pages cannot cope with short copies, and we
2268 * cannot take a pagefault with the destination page locked.
2269 * So pin the source page to copy it.
2271 if (!PageUptodate(page
) && !segment_eq(get_fs(), KERNEL_DS
)) {
2274 src_page
= alloc_page(GFP_KERNEL
);
2276 page_cache_release(page
);
2282 * Cannot get_user_pages with a page locked for the
2283 * same reason as we can't take a page fault with a
2284 * page locked (as explained below).
2286 copied
= iov_iter_copy_from_user(src_page
, i
,
2288 if (unlikely(copied
== 0)) {
2290 page_cache_release(page
);
2291 page_cache_release(src_page
);
2298 * Can't handle the page going uptodate here, because
2299 * that means we would use non-atomic usercopies, which
2300 * zero out the tail of the page, which can cause
2301 * zeroes to become transiently visible. We could just
2302 * use a non-zeroing copy, but the APIs aren't too
2305 if (unlikely(!page
->mapping
|| PageUptodate(page
))) {
2307 page_cache_release(page
);
2308 page_cache_release(src_page
);
2313 status
= a_ops
->prepare_write(file
, page
, offset
, offset
+bytes
);
2314 if (unlikely(status
))
2315 goto fs_write_aop_error
;
2319 * Must not enter the pagefault handler here, because
2320 * we hold the page lock, so we might recursively
2321 * deadlock on the same lock, or get an ABBA deadlock
2322 * against a different lock, or against the mmap_sem
2323 * (which nests outside the page lock). So increment
2324 * preempt count, and use _atomic usercopies.
2326 * The page is uptodate so we are OK to encounter a
2327 * short copy: if unmodified parts of the page are
2328 * marked dirty and written out to disk, it doesn't
2331 pagefault_disable();
2332 copied
= iov_iter_copy_from_user_atomic(page
, i
,
2337 src
= kmap_atomic(src_page
, KM_USER0
);
2338 dst
= kmap_atomic(page
, KM_USER1
);
2339 memcpy(dst
+ offset
, src
+ offset
, bytes
);
2340 kunmap_atomic(dst
, KM_USER1
);
2341 kunmap_atomic(src
, KM_USER0
);
2344 flush_dcache_page(page
);
2346 status
= a_ops
->commit_write(file
, page
, offset
, offset
+bytes
);
2347 if (unlikely(status
< 0))
2348 goto fs_write_aop_error
;
2349 if (unlikely(status
> 0)) /* filesystem did partial write */
2350 copied
= min_t(size_t, copied
, status
);
2353 mark_page_accessed(page
);
2354 page_cache_release(page
);
2356 page_cache_release(src_page
);
2358 iov_iter_advance(i
, copied
);
2362 balance_dirty_pages_ratelimited(mapping
);
2368 page_cache_release(page
);
2370 page_cache_release(src_page
);
2373 * prepare_write() may have instantiated a few blocks
2374 * outside i_size. Trim these off again. Don't need
2375 * i_size_read because we hold i_mutex.
2377 if (pos
+ bytes
> inode
->i_size
)
2378 vmtruncate(inode
, inode
->i_size
);
2380 } while (iov_iter_count(i
));
2382 return written
? written
: status
;
2385 static ssize_t
generic_perform_write(struct file
*file
,
2386 struct iov_iter
*i
, loff_t pos
)
2388 struct address_space
*mapping
= file
->f_mapping
;
2389 const struct address_space_operations
*a_ops
= mapping
->a_ops
;
2391 ssize_t written
= 0;
2392 unsigned int flags
= 0;
2395 * Copies from kernel address space cannot fail (NFSD is a big user).
2397 if (segment_eq(get_fs(), KERNEL_DS
))
2398 flags
|= AOP_FLAG_UNINTERRUPTIBLE
;
2402 pgoff_t index
; /* Pagecache index for current page */
2403 unsigned long offset
; /* Offset into pagecache page */
2404 unsigned long bytes
; /* Bytes to write to page */
2405 size_t copied
; /* Bytes copied from user */
2408 offset
= (pos
& (PAGE_CACHE_SIZE
- 1));
2409 index
= pos
>> PAGE_CACHE_SHIFT
;
2410 bytes
= min_t(unsigned long, PAGE_CACHE_SIZE
- offset
,
2416 * Bring in the user page that we will copy from _first_.
2417 * Otherwise there's a nasty deadlock on copying from the
2418 * same page as we're writing to, without it being marked
2421 * Not only is this an optimisation, but it is also required
2422 * to check that the address is actually valid, when atomic
2423 * usercopies are used, below.
2425 if (unlikely(iov_iter_fault_in_readable(i
, bytes
))) {
2430 status
= a_ops
->write_begin(file
, mapping
, pos
, bytes
, flags
,
2432 if (unlikely(status
))
2435 pagefault_disable();
2436 copied
= iov_iter_copy_from_user_atomic(page
, i
, offset
, bytes
);
2438 flush_dcache_page(page
);
2440 status
= a_ops
->write_end(file
, mapping
, pos
, bytes
, copied
,
2442 if (unlikely(status
< 0))
2448 iov_iter_advance(i
, copied
);
2449 if (unlikely(copied
== 0)) {
2451 * If we were unable to copy any data at all, we must
2452 * fall back to a single segment length write.
2454 * If we didn't fallback here, we could livelock
2455 * because not all segments in the iov can be copied at
2456 * once without a pagefault.
2458 bytes
= min_t(unsigned long, PAGE_CACHE_SIZE
- offset
,
2459 iov_iter_single_seg_count(i
));
2465 balance_dirty_pages_ratelimited(mapping
);
2467 } while (iov_iter_count(i
));
2469 return written
? written
: status
;
2473 generic_file_buffered_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2474 unsigned long nr_segs
, loff_t pos
, loff_t
*ppos
,
2475 size_t count
, ssize_t written
)
2477 struct file
*file
= iocb
->ki_filp
;
2478 struct address_space
*mapping
= file
->f_mapping
;
2479 const struct address_space_operations
*a_ops
= mapping
->a_ops
;
2480 struct inode
*inode
= mapping
->host
;
2484 iov_iter_init(&i
, iov
, nr_segs
, count
, written
);
2485 if (a_ops
->write_begin
)
2486 status
= generic_perform_write(file
, &i
, pos
);
2488 status
= generic_perform_write_2copy(file
, &i
, pos
);
2490 if (likely(status
>= 0)) {
2492 *ppos
= pos
+ status
;
2495 * For now, when the user asks for O_SYNC, we'll actually give
2498 if (unlikely((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2499 if (!a_ops
->writepage
|| !is_sync_kiocb(iocb
))
2500 status
= generic_osync_inode(inode
, mapping
,
2501 OSYNC_METADATA
|OSYNC_DATA
);
2506 * If we get here for O_DIRECT writes then we must have fallen through
2507 * to buffered writes (block instantiation inside i_size). So we sync
2508 * the file data here, to try to honour O_DIRECT expectations.
2510 if (unlikely(file
->f_flags
& O_DIRECT
) && written
)
2511 status
= filemap_write_and_wait(mapping
);
2513 return written
? written
: status
;
2515 EXPORT_SYMBOL(generic_file_buffered_write
);
2518 __generic_file_aio_write_nolock(struct kiocb
*iocb
, const struct iovec
*iov
,
2519 unsigned long nr_segs
, loff_t
*ppos
)
2521 struct file
*file
= iocb
->ki_filp
;
2522 struct address_space
* mapping
= file
->f_mapping
;
2523 size_t ocount
; /* original count */
2524 size_t count
; /* after file limit checks */
2525 struct inode
*inode
= mapping
->host
;
2531 err
= generic_segment_checks(iov
, &nr_segs
, &ocount
, VERIFY_READ
);
2538 vfs_check_frozen(inode
->i_sb
, SB_FREEZE_WRITE
);
2540 /* We can write back this queue in page reclaim */
2541 current
->backing_dev_info
= mapping
->backing_dev_info
;
2544 err
= generic_write_checks(file
, &pos
, &count
, S_ISBLK(inode
->i_mode
));
2551 err
= file_remove_suid(file
);
2555 file_update_time(file
);
2557 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2558 if (unlikely(file
->f_flags
& O_DIRECT
)) {
2560 ssize_t written_buffered
;
2562 written
= generic_file_direct_write(iocb
, iov
, &nr_segs
, pos
,
2563 ppos
, count
, ocount
);
2564 if (written
< 0 || written
== count
)
2567 * direct-io write to a hole: fall through to buffered I/O
2568 * for completing the rest of the request.
2572 written_buffered
= generic_file_buffered_write(iocb
, iov
,
2573 nr_segs
, pos
, ppos
, count
,
2576 * If generic_file_buffered_write() retuned a synchronous error
2577 * then we want to return the number of bytes which were
2578 * direct-written, or the error code if that was zero. Note
2579 * that this differs from normal direct-io semantics, which
2580 * will return -EFOO even if some bytes were written.
2582 if (written_buffered
< 0) {
2583 err
= written_buffered
;
2588 * We need to ensure that the page cache pages are written to
2589 * disk and invalidated to preserve the expected O_DIRECT
2592 endbyte
= pos
+ written_buffered
- written
- 1;
2593 err
= do_sync_mapping_range(file
->f_mapping
, pos
, endbyte
,
2594 SYNC_FILE_RANGE_WAIT_BEFORE
|
2595 SYNC_FILE_RANGE_WRITE
|
2596 SYNC_FILE_RANGE_WAIT_AFTER
);
2598 written
= written_buffered
;
2599 invalidate_mapping_pages(mapping
,
2600 pos
>> PAGE_CACHE_SHIFT
,
2601 endbyte
>> PAGE_CACHE_SHIFT
);
2604 * We don't know how much we wrote, so just return
2605 * the number of bytes which were direct-written
2609 written
= generic_file_buffered_write(iocb
, iov
, nr_segs
,
2610 pos
, ppos
, count
, written
);
2613 current
->backing_dev_info
= NULL
;
2614 return written
? written
: err
;
2617 ssize_t
generic_file_aio_write_nolock(struct kiocb
*iocb
,
2618 const struct iovec
*iov
, unsigned long nr_segs
, loff_t pos
)
2620 struct file
*file
= iocb
->ki_filp
;
2621 struct address_space
*mapping
= file
->f_mapping
;
2622 struct inode
*inode
= mapping
->host
;
2625 BUG_ON(iocb
->ki_pos
!= pos
);
2627 ret
= __generic_file_aio_write_nolock(iocb
, iov
, nr_segs
,
2630 if (ret
> 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2633 err
= sync_page_range_nolock(inode
, mapping
, pos
, ret
);
2639 EXPORT_SYMBOL(generic_file_aio_write_nolock
);
2641 ssize_t
generic_file_aio_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2642 unsigned long nr_segs
, loff_t pos
)
2644 struct file
*file
= iocb
->ki_filp
;
2645 struct address_space
*mapping
= file
->f_mapping
;
2646 struct inode
*inode
= mapping
->host
;
2649 BUG_ON(iocb
->ki_pos
!= pos
);
2651 mutex_lock(&inode
->i_mutex
);
2652 ret
= __generic_file_aio_write_nolock(iocb
, iov
, nr_segs
,
2654 mutex_unlock(&inode
->i_mutex
);
2656 if (ret
> 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2659 err
= sync_page_range(inode
, mapping
, pos
, ret
);
2665 EXPORT_SYMBOL(generic_file_aio_write
);
2668 * try_to_release_page() - release old fs-specific metadata on a page
2670 * @page: the page which the kernel is trying to free
2671 * @gfp_mask: memory allocation flags (and I/O mode)
2673 * The address_space is to try to release any data against the page
2674 * (presumably at page->private). If the release was successful, return `1'.
2675 * Otherwise return zero.
2677 * The @gfp_mask argument specifies whether I/O may be performed to release
2678 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
2681 int try_to_release_page(struct page
*page
, gfp_t gfp_mask
)
2683 struct address_space
* const mapping
= page
->mapping
;
2685 BUG_ON(!PageLocked(page
));
2686 if (PageWriteback(page
))
2689 if (mapping
&& mapping
->a_ops
->releasepage
)
2690 return mapping
->a_ops
->releasepage(page
, gfp_mask
);
2691 return try_to_free_buffers(page
);
2694 EXPORT_SYMBOL(try_to_release_page
);