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/compiler.h>
15 #include <linux/uaccess.h>
16 #include <linux/aio.h>
17 #include <linux/capability.h>
18 #include <linux/kernel_stat.h>
19 #include <linux/gfp.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>
36 #include <linux/mm_inline.h> /* for page_is_file_cache() */
37 #include <linux/cleancache.h>
41 * FIXME: remove all knowledge of the buffer layer from the core VM
43 #include <linux/buffer_head.h> /* for try_to_free_buffers */
48 * Shared mappings implemented 30.11.1994. It's not fully working yet,
51 * Shared mappings now work. 15.8.1995 Bruno.
53 * finished 'unifying' the page and buffer cache and SMP-threaded the
54 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
56 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
62 * ->i_mmap_mutex (truncate_pagecache)
63 * ->private_lock (__free_pte->__set_page_dirty_buffers)
64 * ->swap_lock (exclusive_swap_page, others)
65 * ->mapping->tree_lock
68 * ->i_mmap_mutex (truncate->unmap_mapping_range)
72 * ->page_table_lock or pte_lock (various, mainly in memory.c)
73 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
76 * ->lock_page (access_process_vm)
78 * ->i_mutex (generic_file_buffered_write)
79 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
82 * sb_lock (fs/fs-writeback.c)
83 * ->mapping->tree_lock (__sync_single_inode)
86 * ->anon_vma.lock (vma_adjust)
89 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
91 * ->page_table_lock or pte_lock
92 * ->swap_lock (try_to_unmap_one)
93 * ->private_lock (try_to_unmap_one)
94 * ->tree_lock (try_to_unmap_one)
95 * ->zone.lru_lock (follow_page->mark_page_accessed)
96 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
97 * ->private_lock (page_remove_rmap->set_page_dirty)
98 * ->tree_lock (page_remove_rmap->set_page_dirty)
99 * bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
100 * ->inode->i_lock (page_remove_rmap->set_page_dirty)
101 * bdi.wb->list_lock (zap_pte_range->set_page_dirty)
102 * ->inode->i_lock (zap_pte_range->set_page_dirty)
103 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
105 * (code doesn't rely on that order, so you could switch it around)
106 * ->tasklist_lock (memory_failure, collect_procs_ao)
111 * Delete a page from the page cache and free it. Caller has to make
112 * sure the page is locked and that nobody else uses it - or that usage
113 * is safe. The caller must hold the mapping's tree_lock.
115 void __delete_from_page_cache(struct page
*page
)
117 struct address_space
*mapping
= page
->mapping
;
120 * if we're uptodate, flush out into the cleancache, otherwise
121 * invalidate any existing cleancache entries. We can't leave
122 * stale data around in the cleancache once our page is gone
124 if (PageUptodate(page
) && PageMappedToDisk(page
))
125 cleancache_put_page(page
);
127 cleancache_flush_page(mapping
, page
);
129 radix_tree_delete(&mapping
->page_tree
, page
->index
);
130 page
->mapping
= NULL
;
131 /* Leave page->index set: truncation lookup relies upon it */
133 __dec_zone_page_state(page
, NR_FILE_PAGES
);
134 if (PageSwapBacked(page
))
135 __dec_zone_page_state(page
, NR_SHMEM
);
136 BUG_ON(page_mapped(page
));
139 * Some filesystems seem to re-dirty the page even after
140 * the VM has canceled the dirty bit (eg ext3 journaling).
142 * Fix it up by doing a final dirty accounting check after
143 * having removed the page entirely.
145 if (PageDirty(page
) && mapping_cap_account_dirty(mapping
)) {
146 dec_zone_page_state(page
, NR_FILE_DIRTY
);
147 dec_bdi_stat(mapping
->backing_dev_info
, BDI_RECLAIMABLE
);
152 * delete_from_page_cache - delete page from page cache
153 * @page: the page which the kernel is trying to remove from page cache
155 * This must be called only on pages that have been verified to be in the page
156 * cache and locked. It will never put the page into the free list, the caller
157 * has a reference on the page.
159 void delete_from_page_cache(struct page
*page
)
161 struct address_space
*mapping
= page
->mapping
;
162 void (*freepage
)(struct page
*);
164 BUG_ON(!PageLocked(page
));
166 freepage
= mapping
->a_ops
->freepage
;
167 spin_lock_irq(&mapping
->tree_lock
);
168 __delete_from_page_cache(page
);
169 spin_unlock_irq(&mapping
->tree_lock
);
170 mem_cgroup_uncharge_cache_page(page
);
174 page_cache_release(page
);
176 EXPORT_SYMBOL(delete_from_page_cache
);
178 static int sleep_on_page(void *word
)
184 static int sleep_on_page_killable(void *word
)
187 return fatal_signal_pending(current
) ? -EINTR
: 0;
191 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
192 * @mapping: address space structure to write
193 * @start: offset in bytes where the range starts
194 * @end: offset in bytes where the range ends (inclusive)
195 * @sync_mode: enable synchronous operation
197 * Start writeback against all of a mapping's dirty pages that lie
198 * within the byte offsets <start, end> inclusive.
200 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
201 * opposed to a regular memory cleansing writeback. The difference between
202 * these two operations is that if a dirty page/buffer is encountered, it must
203 * be waited upon, and not just skipped over.
205 int __filemap_fdatawrite_range(struct address_space
*mapping
, loff_t start
,
206 loff_t end
, int sync_mode
)
209 struct writeback_control wbc
= {
210 .sync_mode
= sync_mode
,
211 .nr_to_write
= LONG_MAX
,
212 .range_start
= start
,
216 if (!mapping_cap_writeback_dirty(mapping
))
219 ret
= do_writepages(mapping
, &wbc
);
223 static inline int __filemap_fdatawrite(struct address_space
*mapping
,
226 return __filemap_fdatawrite_range(mapping
, 0, LLONG_MAX
, sync_mode
);
229 int filemap_fdatawrite(struct address_space
*mapping
)
231 return __filemap_fdatawrite(mapping
, WB_SYNC_ALL
);
233 EXPORT_SYMBOL(filemap_fdatawrite
);
235 int filemap_fdatawrite_range(struct address_space
*mapping
, loff_t start
,
238 return __filemap_fdatawrite_range(mapping
, start
, end
, WB_SYNC_ALL
);
240 EXPORT_SYMBOL(filemap_fdatawrite_range
);
243 * filemap_flush - mostly a non-blocking flush
244 * @mapping: target address_space
246 * This is a mostly non-blocking flush. Not suitable for data-integrity
247 * purposes - I/O may not be started against all dirty pages.
249 int filemap_flush(struct address_space
*mapping
)
251 return __filemap_fdatawrite(mapping
, WB_SYNC_NONE
);
253 EXPORT_SYMBOL(filemap_flush
);
256 * filemap_fdatawait_range - wait for writeback to complete
257 * @mapping: address space structure to wait for
258 * @start_byte: offset in bytes where the range starts
259 * @end_byte: offset in bytes where the range ends (inclusive)
261 * Walk the list of under-writeback pages of the given address space
262 * in the given range and wait for all of them.
264 int filemap_fdatawait_range(struct address_space
*mapping
, loff_t start_byte
,
267 pgoff_t index
= start_byte
>> PAGE_CACHE_SHIFT
;
268 pgoff_t end
= end_byte
>> PAGE_CACHE_SHIFT
;
273 if (end_byte
< start_byte
)
276 pagevec_init(&pvec
, 0);
277 while ((index
<= end
) &&
278 (nr_pages
= pagevec_lookup_tag(&pvec
, mapping
, &index
,
279 PAGECACHE_TAG_WRITEBACK
,
280 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
-1) + 1)) != 0) {
283 for (i
= 0; i
< nr_pages
; i
++) {
284 struct page
*page
= pvec
.pages
[i
];
286 /* until radix tree lookup accepts end_index */
287 if (page
->index
> end
)
290 wait_on_page_writeback(page
);
291 if (TestClearPageError(page
))
294 pagevec_release(&pvec
);
298 /* Check for outstanding write errors */
299 if (test_and_clear_bit(AS_ENOSPC
, &mapping
->flags
))
301 if (test_and_clear_bit(AS_EIO
, &mapping
->flags
))
306 EXPORT_SYMBOL(filemap_fdatawait_range
);
309 * filemap_fdatawait - wait for all under-writeback pages to complete
310 * @mapping: address space structure to wait for
312 * Walk the list of under-writeback pages of the given address space
313 * and wait for all of them.
315 int filemap_fdatawait(struct address_space
*mapping
)
317 loff_t i_size
= i_size_read(mapping
->host
);
322 return filemap_fdatawait_range(mapping
, 0, i_size
- 1);
324 EXPORT_SYMBOL(filemap_fdatawait
);
326 int filemap_write_and_wait(struct address_space
*mapping
)
330 if (mapping
->nrpages
) {
331 err
= filemap_fdatawrite(mapping
);
333 * Even if the above returned error, the pages may be
334 * written partially (e.g. -ENOSPC), so we wait for it.
335 * But the -EIO is special case, it may indicate the worst
336 * thing (e.g. bug) happened, so we avoid waiting for it.
339 int err2
= filemap_fdatawait(mapping
);
346 EXPORT_SYMBOL(filemap_write_and_wait
);
349 * filemap_write_and_wait_range - write out & wait on a file range
350 * @mapping: the address_space for the pages
351 * @lstart: offset in bytes where the range starts
352 * @lend: offset in bytes where the range ends (inclusive)
354 * Write out and wait upon file offsets lstart->lend, inclusive.
356 * Note that `lend' is inclusive (describes the last byte to be written) so
357 * that this function can be used to write to the very end-of-file (end = -1).
359 int filemap_write_and_wait_range(struct address_space
*mapping
,
360 loff_t lstart
, loff_t lend
)
364 if (mapping
->nrpages
) {
365 err
= __filemap_fdatawrite_range(mapping
, lstart
, lend
,
367 /* See comment of filemap_write_and_wait() */
369 int err2
= filemap_fdatawait_range(mapping
,
377 EXPORT_SYMBOL(filemap_write_and_wait_range
);
380 * replace_page_cache_page - replace a pagecache page with a new one
381 * @old: page to be replaced
382 * @new: page to replace with
383 * @gfp_mask: allocation mode
385 * This function replaces a page in the pagecache with a new one. On
386 * success it acquires the pagecache reference for the new page and
387 * drops it for the old page. Both the old and new pages must be
388 * locked. This function does not add the new page to the LRU, the
389 * caller must do that.
391 * The remove + add is atomic. The only way this function can fail is
392 * memory allocation failure.
394 int replace_page_cache_page(struct page
*old
, struct page
*new, gfp_t gfp_mask
)
397 struct mem_cgroup
*memcg
= NULL
;
399 VM_BUG_ON(!PageLocked(old
));
400 VM_BUG_ON(!PageLocked(new));
401 VM_BUG_ON(new->mapping
);
404 * This is not page migration, but prepare_migration and
405 * end_migration does enough work for charge replacement.
407 * In the longer term we probably want a specialized function
408 * for moving the charge from old to new in a more efficient
411 error
= mem_cgroup_prepare_migration(old
, new, &memcg
, gfp_mask
);
415 error
= radix_tree_preload(gfp_mask
& ~__GFP_HIGHMEM
);
417 struct address_space
*mapping
= old
->mapping
;
418 void (*freepage
)(struct page
*);
420 pgoff_t offset
= old
->index
;
421 freepage
= mapping
->a_ops
->freepage
;
424 new->mapping
= mapping
;
427 spin_lock_irq(&mapping
->tree_lock
);
428 __delete_from_page_cache(old
);
429 error
= radix_tree_insert(&mapping
->page_tree
, offset
, new);
432 __inc_zone_page_state(new, NR_FILE_PAGES
);
433 if (PageSwapBacked(new))
434 __inc_zone_page_state(new, NR_SHMEM
);
435 spin_unlock_irq(&mapping
->tree_lock
);
436 radix_tree_preload_end();
439 page_cache_release(old
);
440 mem_cgroup_end_migration(memcg
, old
, new, true);
442 mem_cgroup_end_migration(memcg
, old
, new, false);
447 EXPORT_SYMBOL_GPL(replace_page_cache_page
);
450 * add_to_page_cache_locked - add a locked page to the pagecache
452 * @mapping: the page's address_space
453 * @offset: page index
454 * @gfp_mask: page allocation mode
456 * This function is used to add a page to the pagecache. It must be locked.
457 * This function does not add the page to the LRU. The caller must do that.
459 int add_to_page_cache_locked(struct page
*page
, struct address_space
*mapping
,
460 pgoff_t offset
, gfp_t gfp_mask
)
464 VM_BUG_ON(!PageLocked(page
));
466 error
= mem_cgroup_cache_charge(page
, current
->mm
,
467 gfp_mask
& GFP_RECLAIM_MASK
);
471 error
= radix_tree_preload(gfp_mask
& ~__GFP_HIGHMEM
);
473 page_cache_get(page
);
474 page
->mapping
= mapping
;
475 page
->index
= offset
;
477 spin_lock_irq(&mapping
->tree_lock
);
478 error
= radix_tree_insert(&mapping
->page_tree
, offset
, page
);
479 if (likely(!error
)) {
481 __inc_zone_page_state(page
, NR_FILE_PAGES
);
482 if (PageSwapBacked(page
))
483 __inc_zone_page_state(page
, NR_SHMEM
);
484 spin_unlock_irq(&mapping
->tree_lock
);
486 page
->mapping
= NULL
;
487 /* Leave page->index set: truncation relies upon it */
488 spin_unlock_irq(&mapping
->tree_lock
);
489 mem_cgroup_uncharge_cache_page(page
);
490 page_cache_release(page
);
492 radix_tree_preload_end();
494 mem_cgroup_uncharge_cache_page(page
);
498 EXPORT_SYMBOL(add_to_page_cache_locked
);
500 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
501 pgoff_t offset
, gfp_t gfp_mask
)
506 * Splice_read and readahead add shmem/tmpfs pages into the page cache
507 * before shmem_readpage has a chance to mark them as SwapBacked: they
508 * need to go on the anon lru below, and mem_cgroup_cache_charge
509 * (called in add_to_page_cache) needs to know where they're going too.
511 if (mapping_cap_swap_backed(mapping
))
512 SetPageSwapBacked(page
);
514 ret
= add_to_page_cache(page
, mapping
, offset
, gfp_mask
);
516 if (page_is_file_cache(page
))
517 lru_cache_add_file(page
);
519 lru_cache_add_anon(page
);
523 EXPORT_SYMBOL_GPL(add_to_page_cache_lru
);
526 struct page
*__page_cache_alloc(gfp_t gfp
)
531 if (cpuset_do_page_mem_spread()) {
533 n
= cpuset_mem_spread_node();
534 page
= alloc_pages_exact_node(n
, gfp
, 0);
538 return alloc_pages(gfp
, 0);
540 EXPORT_SYMBOL(__page_cache_alloc
);
544 * In order to wait for pages to become available there must be
545 * waitqueues associated with pages. By using a hash table of
546 * waitqueues where the bucket discipline is to maintain all
547 * waiters on the same queue and wake all when any of the pages
548 * become available, and for the woken contexts to check to be
549 * sure the appropriate page became available, this saves space
550 * at a cost of "thundering herd" phenomena during rare hash
553 static wait_queue_head_t
*page_waitqueue(struct page
*page
)
555 const struct zone
*zone
= page_zone(page
);
557 return &zone
->wait_table
[hash_ptr(page
, zone
->wait_table_bits
)];
560 static inline void wake_up_page(struct page
*page
, int bit
)
562 __wake_up_bit(page_waitqueue(page
), &page
->flags
, bit
);
565 void wait_on_page_bit(struct page
*page
, int bit_nr
)
567 DEFINE_WAIT_BIT(wait
, &page
->flags
, bit_nr
);
569 if (test_bit(bit_nr
, &page
->flags
))
570 __wait_on_bit(page_waitqueue(page
), &wait
, sleep_on_page
,
571 TASK_UNINTERRUPTIBLE
);
573 EXPORT_SYMBOL(wait_on_page_bit
);
575 int wait_on_page_bit_killable(struct page
*page
, int bit_nr
)
577 DEFINE_WAIT_BIT(wait
, &page
->flags
, bit_nr
);
579 if (!test_bit(bit_nr
, &page
->flags
))
582 return __wait_on_bit(page_waitqueue(page
), &wait
,
583 sleep_on_page_killable
, TASK_KILLABLE
);
587 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
588 * @page: Page defining the wait queue of interest
589 * @waiter: Waiter to add to the queue
591 * Add an arbitrary @waiter to the wait queue for the nominated @page.
593 void add_page_wait_queue(struct page
*page
, wait_queue_t
*waiter
)
595 wait_queue_head_t
*q
= page_waitqueue(page
);
598 spin_lock_irqsave(&q
->lock
, flags
);
599 __add_wait_queue(q
, waiter
);
600 spin_unlock_irqrestore(&q
->lock
, flags
);
602 EXPORT_SYMBOL_GPL(add_page_wait_queue
);
605 * unlock_page - unlock a locked page
608 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
609 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
610 * mechananism between PageLocked pages and PageWriteback pages is shared.
611 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
613 * The mb is necessary to enforce ordering between the clear_bit and the read
614 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
616 void unlock_page(struct page
*page
)
618 VM_BUG_ON(!PageLocked(page
));
619 clear_bit_unlock(PG_locked
, &page
->flags
);
620 smp_mb__after_clear_bit();
621 wake_up_page(page
, PG_locked
);
623 EXPORT_SYMBOL(unlock_page
);
626 * end_page_writeback - end writeback against a page
629 void end_page_writeback(struct page
*page
)
631 if (TestClearPageReclaim(page
))
632 rotate_reclaimable_page(page
);
634 if (!test_clear_page_writeback(page
))
637 smp_mb__after_clear_bit();
638 wake_up_page(page
, PG_writeback
);
640 EXPORT_SYMBOL(end_page_writeback
);
643 * __lock_page - get a lock on the page, assuming we need to sleep to get it
644 * @page: the page to lock
646 void __lock_page(struct page
*page
)
648 DEFINE_WAIT_BIT(wait
, &page
->flags
, PG_locked
);
650 __wait_on_bit_lock(page_waitqueue(page
), &wait
, sleep_on_page
,
651 TASK_UNINTERRUPTIBLE
);
653 EXPORT_SYMBOL(__lock_page
);
655 int __lock_page_killable(struct page
*page
)
657 DEFINE_WAIT_BIT(wait
, &page
->flags
, PG_locked
);
659 return __wait_on_bit_lock(page_waitqueue(page
), &wait
,
660 sleep_on_page_killable
, TASK_KILLABLE
);
662 EXPORT_SYMBOL_GPL(__lock_page_killable
);
664 int __lock_page_or_retry(struct page
*page
, struct mm_struct
*mm
,
667 if (flags
& FAULT_FLAG_ALLOW_RETRY
) {
669 * CAUTION! In this case, mmap_sem is not released
670 * even though return 0.
672 if (flags
& FAULT_FLAG_RETRY_NOWAIT
)
675 up_read(&mm
->mmap_sem
);
676 if (flags
& FAULT_FLAG_KILLABLE
)
677 wait_on_page_locked_killable(page
);
679 wait_on_page_locked(page
);
682 if (flags
& FAULT_FLAG_KILLABLE
) {
685 ret
= __lock_page_killable(page
);
687 up_read(&mm
->mmap_sem
);
697 * find_get_page - find and get a page reference
698 * @mapping: the address_space to search
699 * @offset: the page index
701 * Is there a pagecache struct page at the given (mapping, offset) tuple?
702 * If yes, increment its refcount and return it; if no, return NULL.
704 struct page
*find_get_page(struct address_space
*mapping
, pgoff_t offset
)
712 pagep
= radix_tree_lookup_slot(&mapping
->page_tree
, offset
);
714 page
= radix_tree_deref_slot(pagep
);
717 if (radix_tree_exception(page
)) {
718 if (radix_tree_exceptional_entry(page
))
720 /* radix_tree_deref_retry(page) */
723 if (!page_cache_get_speculative(page
))
727 * Has the page moved?
728 * This is part of the lockless pagecache protocol. See
729 * include/linux/pagemap.h for details.
731 if (unlikely(page
!= *pagep
)) {
732 page_cache_release(page
);
741 EXPORT_SYMBOL(find_get_page
);
744 * find_lock_page - locate, pin and lock a pagecache page
745 * @mapping: the address_space to search
746 * @offset: the page index
748 * Locates the desired pagecache page, locks it, increments its reference
749 * count and returns its address.
751 * Returns zero if the page was not present. find_lock_page() may sleep.
753 struct page
*find_lock_page(struct address_space
*mapping
, pgoff_t offset
)
758 page
= find_get_page(mapping
, offset
);
759 if (page
&& !radix_tree_exception(page
)) {
761 /* Has the page been truncated? */
762 if (unlikely(page
->mapping
!= mapping
)) {
764 page_cache_release(page
);
767 VM_BUG_ON(page
->index
!= offset
);
771 EXPORT_SYMBOL(find_lock_page
);
774 * find_or_create_page - locate or add a pagecache page
775 * @mapping: the page's address_space
776 * @index: the page's index into the mapping
777 * @gfp_mask: page allocation mode
779 * Locates a page in the pagecache. If the page is not present, a new page
780 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
781 * LRU list. The returned page is locked and has its reference count
784 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
787 * find_or_create_page() returns the desired page's address, or zero on
790 struct page
*find_or_create_page(struct address_space
*mapping
,
791 pgoff_t index
, gfp_t gfp_mask
)
796 page
= find_lock_page(mapping
, index
);
798 page
= __page_cache_alloc(gfp_mask
);
802 * We want a regular kernel memory (not highmem or DMA etc)
803 * allocation for the radix tree nodes, but we need to honour
804 * the context-specific requirements the caller has asked for.
805 * GFP_RECLAIM_MASK collects those requirements.
807 err
= add_to_page_cache_lru(page
, mapping
, index
,
808 (gfp_mask
& GFP_RECLAIM_MASK
));
810 page_cache_release(page
);
818 EXPORT_SYMBOL(find_or_create_page
);
821 * find_get_pages - gang pagecache lookup
822 * @mapping: The address_space to search
823 * @start: The starting page index
824 * @nr_pages: The maximum number of pages
825 * @pages: Where the resulting pages are placed
827 * find_get_pages() will search for and return a group of up to
828 * @nr_pages pages in the mapping. The pages are placed at @pages.
829 * find_get_pages() takes a reference against the returned pages.
831 * The search returns a group of mapping-contiguous pages with ascending
832 * indexes. There may be holes in the indices due to not-present pages.
834 * find_get_pages() returns the number of pages which were found.
836 unsigned find_get_pages(struct address_space
*mapping
, pgoff_t start
,
837 unsigned int nr_pages
, struct page
**pages
)
841 unsigned int nr_found
;
845 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
846 (void ***)pages
, NULL
, start
, nr_pages
);
848 for (i
= 0; i
< nr_found
; i
++) {
851 page
= radix_tree_deref_slot((void **)pages
[i
]);
855 if (radix_tree_exception(page
)) {
856 if (radix_tree_exceptional_entry(page
))
859 * radix_tree_deref_retry(page):
860 * can only trigger when entry at index 0 moves out of
861 * or back to root: none yet gotten, safe to restart.
867 if (!page_cache_get_speculative(page
))
870 /* Has the page moved? */
871 if (unlikely(page
!= *((void **)pages
[i
]))) {
872 page_cache_release(page
);
881 * If all entries were removed before we could secure them,
882 * try again, because callers stop trying once 0 is returned.
884 if (unlikely(!ret
&& nr_found
))
891 * find_get_pages_contig - gang contiguous pagecache lookup
892 * @mapping: The address_space to search
893 * @index: The starting page index
894 * @nr_pages: The maximum number of pages
895 * @pages: Where the resulting pages are placed
897 * find_get_pages_contig() works exactly like find_get_pages(), except
898 * that the returned number of pages are guaranteed to be contiguous.
900 * find_get_pages_contig() returns the number of pages which were found.
902 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t index
,
903 unsigned int nr_pages
, struct page
**pages
)
907 unsigned int nr_found
;
911 nr_found
= radix_tree_gang_lookup_slot(&mapping
->page_tree
,
912 (void ***)pages
, NULL
, index
, nr_pages
);
914 for (i
= 0; i
< nr_found
; i
++) {
917 page
= radix_tree_deref_slot((void **)pages
[i
]);
921 if (radix_tree_exception(page
)) {
922 if (radix_tree_exceptional_entry(page
))
925 * radix_tree_deref_retry(page):
926 * can only trigger when entry at index 0 moves out of
927 * or back to root: none yet gotten, safe to restart.
932 if (!page_cache_get_speculative(page
))
935 /* Has the page moved? */
936 if (unlikely(page
!= *((void **)pages
[i
]))) {
937 page_cache_release(page
);
942 * must check mapping and index after taking the ref.
943 * otherwise we can get both false positives and false
944 * negatives, which is just confusing to the caller.
946 if (page
->mapping
== NULL
|| page
->index
!= index
) {
947 page_cache_release(page
);
958 EXPORT_SYMBOL(find_get_pages_contig
);
961 * find_get_pages_tag - find and return pages that match @tag
962 * @mapping: the address_space to search
963 * @index: the starting page index
964 * @tag: the tag index
965 * @nr_pages: the maximum number of pages
966 * @pages: where the resulting pages are placed
968 * Like find_get_pages, except we only return pages which are tagged with
969 * @tag. We update @index to index the next page for the traversal.
971 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
972 int tag
, unsigned int nr_pages
, struct page
**pages
)
976 unsigned int nr_found
;
980 nr_found
= radix_tree_gang_lookup_tag_slot(&mapping
->page_tree
,
981 (void ***)pages
, *index
, nr_pages
, tag
);
983 for (i
= 0; i
< nr_found
; i
++) {
986 page
= radix_tree_deref_slot((void **)pages
[i
]);
990 if (radix_tree_exception(page
)) {
991 BUG_ON(radix_tree_exceptional_entry(page
));
993 * radix_tree_deref_retry(page):
994 * can only trigger when entry at index 0 moves out of
995 * or back to root: none yet gotten, safe to restart.
1000 if (!page_cache_get_speculative(page
))
1003 /* Has the page moved? */
1004 if (unlikely(page
!= *((void **)pages
[i
]))) {
1005 page_cache_release(page
);
1014 * If all entries were removed before we could secure them,
1015 * try again, because callers stop trying once 0 is returned.
1017 if (unlikely(!ret
&& nr_found
))
1022 *index
= pages
[ret
- 1]->index
+ 1;
1026 EXPORT_SYMBOL(find_get_pages_tag
);
1029 * grab_cache_page_nowait - returns locked page at given index in given cache
1030 * @mapping: target address_space
1031 * @index: the page index
1033 * Same as grab_cache_page(), but do not wait if the page is unavailable.
1034 * This is intended for speculative data generators, where the data can
1035 * be regenerated if the page couldn't be grabbed. This routine should
1036 * be safe to call while holding the lock for another page.
1038 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
1039 * and deadlock against the caller's locked page.
1042 grab_cache_page_nowait(struct address_space
*mapping
, pgoff_t index
)
1044 struct page
*page
= find_get_page(mapping
, index
);
1047 if (trylock_page(page
))
1049 page_cache_release(page
);
1052 page
= __page_cache_alloc(mapping_gfp_mask(mapping
) & ~__GFP_FS
);
1053 if (page
&& add_to_page_cache_lru(page
, mapping
, index
, GFP_NOFS
)) {
1054 page_cache_release(page
);
1059 EXPORT_SYMBOL(grab_cache_page_nowait
);
1062 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
1063 * a _large_ part of the i/o request. Imagine the worst scenario:
1065 * ---R__________________________________________B__________
1066 * ^ reading here ^ bad block(assume 4k)
1068 * read(R) => miss => readahead(R...B) => media error => frustrating retries
1069 * => failing the whole request => read(R) => read(R+1) =>
1070 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
1071 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
1072 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
1074 * It is going insane. Fix it by quickly scaling down the readahead size.
1076 static void shrink_readahead_size_eio(struct file
*filp
,
1077 struct file_ra_state
*ra
)
1083 * do_generic_file_read - generic file read routine
1084 * @filp: the file to read
1085 * @ppos: current file position
1086 * @desc: read_descriptor
1087 * @actor: read method
1089 * This is a generic file read routine, and uses the
1090 * mapping->a_ops->readpage() function for the actual low-level stuff.
1092 * This is really ugly. But the goto's actually try to clarify some
1093 * of the logic when it comes to error handling etc.
1095 static void do_generic_file_read(struct file
*filp
, loff_t
*ppos
,
1096 read_descriptor_t
*desc
, read_actor_t actor
)
1098 struct address_space
*mapping
= filp
->f_mapping
;
1099 struct inode
*inode
= mapping
->host
;
1100 struct file_ra_state
*ra
= &filp
->f_ra
;
1104 unsigned long offset
; /* offset into pagecache page */
1105 unsigned int prev_offset
;
1108 index
= *ppos
>> PAGE_CACHE_SHIFT
;
1109 prev_index
= ra
->prev_pos
>> PAGE_CACHE_SHIFT
;
1110 prev_offset
= ra
->prev_pos
& (PAGE_CACHE_SIZE
-1);
1111 last_index
= (*ppos
+ desc
->count
+ PAGE_CACHE_SIZE
-1) >> PAGE_CACHE_SHIFT
;
1112 offset
= *ppos
& ~PAGE_CACHE_MASK
;
1118 unsigned long nr
, ret
;
1122 page
= find_get_page(mapping
, index
);
1124 page_cache_sync_readahead(mapping
,
1126 index
, last_index
- index
);
1127 page
= find_get_page(mapping
, index
);
1128 if (unlikely(page
== NULL
))
1129 goto no_cached_page
;
1131 if (PageReadahead(page
)) {
1132 page_cache_async_readahead(mapping
,
1134 index
, last_index
- index
);
1136 if (!PageUptodate(page
)) {
1137 if (inode
->i_blkbits
== PAGE_CACHE_SHIFT
||
1138 !mapping
->a_ops
->is_partially_uptodate
)
1139 goto page_not_up_to_date
;
1140 if (!trylock_page(page
))
1141 goto page_not_up_to_date
;
1142 /* Did it get truncated before we got the lock? */
1144 goto page_not_up_to_date_locked
;
1145 if (!mapping
->a_ops
->is_partially_uptodate(page
,
1147 goto page_not_up_to_date_locked
;
1152 * i_size must be checked after we know the page is Uptodate.
1154 * Checking i_size after the check allows us to calculate
1155 * the correct value for "nr", which means the zero-filled
1156 * part of the page is not copied back to userspace (unless
1157 * another truncate extends the file - this is desired though).
1160 isize
= i_size_read(inode
);
1161 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1162 if (unlikely(!isize
|| index
> end_index
)) {
1163 page_cache_release(page
);
1167 /* nr is the maximum number of bytes to copy from this page */
1168 nr
= PAGE_CACHE_SIZE
;
1169 if (index
== end_index
) {
1170 nr
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1172 page_cache_release(page
);
1178 /* If users can be writing to this page using arbitrary
1179 * virtual addresses, take care about potential aliasing
1180 * before reading the page on the kernel side.
1182 if (mapping_writably_mapped(mapping
))
1183 flush_dcache_page(page
);
1186 * When a sequential read accesses a page several times,
1187 * only mark it as accessed the first time.
1189 if (prev_index
!= index
|| offset
!= prev_offset
)
1190 mark_page_accessed(page
);
1194 * Ok, we have the page, and it's up-to-date, so
1195 * now we can copy it to user space...
1197 * The actor routine returns how many bytes were actually used..
1198 * NOTE! This may not be the same as how much of a user buffer
1199 * we filled up (we may be padding etc), so we can only update
1200 * "pos" here (the actor routine has to update the user buffer
1201 * pointers and the remaining count).
1203 ret
= actor(desc
, page
, offset
, nr
);
1205 index
+= offset
>> PAGE_CACHE_SHIFT
;
1206 offset
&= ~PAGE_CACHE_MASK
;
1207 prev_offset
= offset
;
1209 page_cache_release(page
);
1210 if (ret
== nr
&& desc
->count
)
1214 page_not_up_to_date
:
1215 /* Get exclusive access to the page ... */
1216 error
= lock_page_killable(page
);
1217 if (unlikely(error
))
1218 goto readpage_error
;
1220 page_not_up_to_date_locked
:
1221 /* Did it get truncated before we got the lock? */
1222 if (!page
->mapping
) {
1224 page_cache_release(page
);
1228 /* Did somebody else fill it already? */
1229 if (PageUptodate(page
)) {
1236 * A previous I/O error may have been due to temporary
1237 * failures, eg. multipath errors.
1238 * PG_error will be set again if readpage fails.
1240 ClearPageError(page
);
1241 /* Start the actual read. The read will unlock the page. */
1242 error
= mapping
->a_ops
->readpage(filp
, page
);
1244 if (unlikely(error
)) {
1245 if (error
== AOP_TRUNCATED_PAGE
) {
1246 page_cache_release(page
);
1249 goto readpage_error
;
1252 if (!PageUptodate(page
)) {
1253 error
= lock_page_killable(page
);
1254 if (unlikely(error
))
1255 goto readpage_error
;
1256 if (!PageUptodate(page
)) {
1257 if (page
->mapping
== NULL
) {
1259 * invalidate_mapping_pages got it
1262 page_cache_release(page
);
1266 shrink_readahead_size_eio(filp
, ra
);
1268 goto readpage_error
;
1276 /* UHHUH! A synchronous read error occurred. Report it */
1277 desc
->error
= error
;
1278 page_cache_release(page
);
1283 * Ok, it wasn't cached, so we need to create a new
1286 page
= page_cache_alloc_cold(mapping
);
1288 desc
->error
= -ENOMEM
;
1291 error
= add_to_page_cache_lru(page
, mapping
,
1294 page_cache_release(page
);
1295 if (error
== -EEXIST
)
1297 desc
->error
= error
;
1304 ra
->prev_pos
= prev_index
;
1305 ra
->prev_pos
<<= PAGE_CACHE_SHIFT
;
1306 ra
->prev_pos
|= prev_offset
;
1308 *ppos
= ((loff_t
)index
<< PAGE_CACHE_SHIFT
) + offset
;
1309 file_accessed(filp
);
1312 int file_read_actor(read_descriptor_t
*desc
, struct page
*page
,
1313 unsigned long offset
, unsigned long size
)
1316 unsigned long left
, count
= desc
->count
;
1322 * Faults on the destination of a read are common, so do it before
1325 if (!fault_in_pages_writeable(desc
->arg
.buf
, size
)) {
1326 kaddr
= kmap_atomic(page
, KM_USER0
);
1327 left
= __copy_to_user_inatomic(desc
->arg
.buf
,
1328 kaddr
+ offset
, size
);
1329 kunmap_atomic(kaddr
, KM_USER0
);
1334 /* Do it the slow way */
1336 left
= __copy_to_user(desc
->arg
.buf
, kaddr
+ offset
, size
);
1341 desc
->error
= -EFAULT
;
1344 desc
->count
= count
- size
;
1345 desc
->written
+= size
;
1346 desc
->arg
.buf
+= size
;
1351 * Performs necessary checks before doing a write
1352 * @iov: io vector request
1353 * @nr_segs: number of segments in the iovec
1354 * @count: number of bytes to write
1355 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1357 * Adjust number of segments and amount of bytes to write (nr_segs should be
1358 * properly initialized first). Returns appropriate error code that caller
1359 * should return or zero in case that write should be allowed.
1361 int generic_segment_checks(const struct iovec
*iov
,
1362 unsigned long *nr_segs
, size_t *count
, int access_flags
)
1366 for (seg
= 0; seg
< *nr_segs
; seg
++) {
1367 const struct iovec
*iv
= &iov
[seg
];
1370 * If any segment has a negative length, or the cumulative
1371 * length ever wraps negative then return -EINVAL.
1374 if (unlikely((ssize_t
)(cnt
|iv
->iov_len
) < 0))
1376 if (access_ok(access_flags
, iv
->iov_base
, iv
->iov_len
))
1381 cnt
-= iv
->iov_len
; /* This segment is no good */
1387 EXPORT_SYMBOL(generic_segment_checks
);
1390 * generic_file_aio_read - generic filesystem read routine
1391 * @iocb: kernel I/O control block
1392 * @iov: io vector request
1393 * @nr_segs: number of segments in the iovec
1394 * @pos: current file position
1396 * This is the "read()" routine for all filesystems
1397 * that can use the page cache directly.
1400 generic_file_aio_read(struct kiocb
*iocb
, const struct iovec
*iov
,
1401 unsigned long nr_segs
, loff_t pos
)
1403 struct file
*filp
= iocb
->ki_filp
;
1405 unsigned long seg
= 0;
1407 loff_t
*ppos
= &iocb
->ki_pos
;
1408 struct blk_plug plug
;
1411 retval
= generic_segment_checks(iov
, &nr_segs
, &count
, VERIFY_WRITE
);
1415 blk_start_plug(&plug
);
1417 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1418 if (filp
->f_flags
& O_DIRECT
) {
1420 struct address_space
*mapping
;
1421 struct inode
*inode
;
1423 mapping
= filp
->f_mapping
;
1424 inode
= mapping
->host
;
1426 goto out
; /* skip atime */
1427 size
= i_size_read(inode
);
1429 retval
= filemap_write_and_wait_range(mapping
, pos
,
1430 pos
+ iov_length(iov
, nr_segs
) - 1);
1432 retval
= mapping
->a_ops
->direct_IO(READ
, iocb
,
1436 *ppos
= pos
+ retval
;
1441 * Btrfs can have a short DIO read if we encounter
1442 * compressed extents, so if there was an error, or if
1443 * we've already read everything we wanted to, or if
1444 * there was a short read because we hit EOF, go ahead
1445 * and return. Otherwise fallthrough to buffered io for
1446 * the rest of the read.
1448 if (retval
< 0 || !count
|| *ppos
>= size
) {
1449 file_accessed(filp
);
1456 for (seg
= 0; seg
< nr_segs
; seg
++) {
1457 read_descriptor_t desc
;
1461 * If we did a short DIO read we need to skip the section of the
1462 * iov that we've already read data into.
1465 if (count
> iov
[seg
].iov_len
) {
1466 count
-= iov
[seg
].iov_len
;
1474 desc
.arg
.buf
= iov
[seg
].iov_base
+ offset
;
1475 desc
.count
= iov
[seg
].iov_len
- offset
;
1476 if (desc
.count
== 0)
1479 do_generic_file_read(filp
, ppos
, &desc
, file_read_actor
);
1480 retval
+= desc
.written
;
1482 retval
= retval
?: desc
.error
;
1489 blk_finish_plug(&plug
);
1492 EXPORT_SYMBOL(generic_file_aio_read
);
1495 do_readahead(struct address_space
*mapping
, struct file
*filp
,
1496 pgoff_t index
, unsigned long nr
)
1498 if (!mapping
|| !mapping
->a_ops
|| !mapping
->a_ops
->readpage
)
1501 force_page_cache_readahead(mapping
, filp
, index
, nr
);
1505 SYSCALL_DEFINE(readahead
)(int fd
, loff_t offset
, size_t count
)
1513 if (file
->f_mode
& FMODE_READ
) {
1514 struct address_space
*mapping
= file
->f_mapping
;
1515 pgoff_t start
= offset
>> PAGE_CACHE_SHIFT
;
1516 pgoff_t end
= (offset
+ count
- 1) >> PAGE_CACHE_SHIFT
;
1517 unsigned long len
= end
- start
+ 1;
1518 ret
= do_readahead(mapping
, file
, start
, len
);
1524 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1525 asmlinkage
long SyS_readahead(long fd
, loff_t offset
, long count
)
1527 return SYSC_readahead((int) fd
, offset
, (size_t) count
);
1529 SYSCALL_ALIAS(sys_readahead
, SyS_readahead
);
1534 * page_cache_read - adds requested page to the page cache if not already there
1535 * @file: file to read
1536 * @offset: page index
1538 * This adds the requested page to the page cache if it isn't already there,
1539 * and schedules an I/O to read in its contents from disk.
1541 static int page_cache_read(struct file
*file
, pgoff_t offset
)
1543 struct address_space
*mapping
= file
->f_mapping
;
1548 page
= page_cache_alloc_cold(mapping
);
1552 ret
= add_to_page_cache_lru(page
, mapping
, offset
, GFP_KERNEL
);
1554 ret
= mapping
->a_ops
->readpage(file
, page
);
1555 else if (ret
== -EEXIST
)
1556 ret
= 0; /* losing race to add is OK */
1558 page_cache_release(page
);
1560 } while (ret
== AOP_TRUNCATED_PAGE
);
1565 #define MMAP_LOTSAMISS (100)
1568 * Synchronous readahead happens when we don't even find
1569 * a page in the page cache at all.
1571 static void do_sync_mmap_readahead(struct vm_area_struct
*vma
,
1572 struct file_ra_state
*ra
,
1576 unsigned long ra_pages
;
1577 struct address_space
*mapping
= file
->f_mapping
;
1579 /* If we don't want any read-ahead, don't bother */
1580 if (VM_RandomReadHint(vma
))
1585 if (VM_SequentialReadHint(vma
)) {
1586 page_cache_sync_readahead(mapping
, ra
, file
, offset
,
1591 /* Avoid banging the cache line if not needed */
1592 if (ra
->mmap_miss
< MMAP_LOTSAMISS
* 10)
1596 * Do we miss much more than hit in this file? If so,
1597 * stop bothering with read-ahead. It will only hurt.
1599 if (ra
->mmap_miss
> MMAP_LOTSAMISS
)
1605 ra_pages
= max_sane_readahead(ra
->ra_pages
);
1606 ra
->start
= max_t(long, 0, offset
- ra_pages
/ 2);
1607 ra
->size
= ra_pages
;
1608 ra
->async_size
= ra_pages
/ 4;
1609 ra_submit(ra
, mapping
, file
);
1613 * Asynchronous readahead happens when we find the page and PG_readahead,
1614 * so we want to possibly extend the readahead further..
1616 static void do_async_mmap_readahead(struct vm_area_struct
*vma
,
1617 struct file_ra_state
*ra
,
1622 struct address_space
*mapping
= file
->f_mapping
;
1624 /* If we don't want any read-ahead, don't bother */
1625 if (VM_RandomReadHint(vma
))
1627 if (ra
->mmap_miss
> 0)
1629 if (PageReadahead(page
))
1630 page_cache_async_readahead(mapping
, ra
, file
,
1631 page
, offset
, ra
->ra_pages
);
1635 * filemap_fault - read in file data for page fault handling
1636 * @vma: vma in which the fault was taken
1637 * @vmf: struct vm_fault containing details of the fault
1639 * filemap_fault() is invoked via the vma operations vector for a
1640 * mapped memory region to read in file data during a page fault.
1642 * The goto's are kind of ugly, but this streamlines the normal case of having
1643 * it in the page cache, and handles the special cases reasonably without
1644 * having a lot of duplicated code.
1646 int filemap_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1649 struct file
*file
= vma
->vm_file
;
1650 struct address_space
*mapping
= file
->f_mapping
;
1651 struct file_ra_state
*ra
= &file
->f_ra
;
1652 struct inode
*inode
= mapping
->host
;
1653 pgoff_t offset
= vmf
->pgoff
;
1658 size
= (i_size_read(inode
) + PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1660 return VM_FAULT_SIGBUS
;
1663 * Do we have something in the page cache already?
1665 page
= find_get_page(mapping
, offset
);
1668 * We found the page, so try async readahead before
1669 * waiting for the lock.
1671 do_async_mmap_readahead(vma
, ra
, file
, page
, offset
);
1673 /* No page in the page cache at all */
1674 do_sync_mmap_readahead(vma
, ra
, file
, offset
);
1675 count_vm_event(PGMAJFAULT
);
1676 mem_cgroup_count_vm_event(vma
->vm_mm
, PGMAJFAULT
);
1677 ret
= VM_FAULT_MAJOR
;
1679 page
= find_get_page(mapping
, offset
);
1681 goto no_cached_page
;
1684 if (!lock_page_or_retry(page
, vma
->vm_mm
, vmf
->flags
)) {
1685 page_cache_release(page
);
1686 return ret
| VM_FAULT_RETRY
;
1689 /* Did it get truncated? */
1690 if (unlikely(page
->mapping
!= mapping
)) {
1695 VM_BUG_ON(page
->index
!= offset
);
1698 * We have a locked page in the page cache, now we need to check
1699 * that it's up-to-date. If not, it is going to be due to an error.
1701 if (unlikely(!PageUptodate(page
)))
1702 goto page_not_uptodate
;
1705 * Found the page and have a reference on it.
1706 * We must recheck i_size under page lock.
1708 size
= (i_size_read(inode
) + PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1709 if (unlikely(offset
>= size
)) {
1711 page_cache_release(page
);
1712 return VM_FAULT_SIGBUS
;
1716 return ret
| VM_FAULT_LOCKED
;
1720 * We're only likely to ever get here if MADV_RANDOM is in
1723 error
= page_cache_read(file
, offset
);
1726 * The page we want has now been added to the page cache.
1727 * In the unlikely event that someone removed it in the
1728 * meantime, we'll just come back here and read it again.
1734 * An error return from page_cache_read can result if the
1735 * system is low on memory, or a problem occurs while trying
1738 if (error
== -ENOMEM
)
1739 return VM_FAULT_OOM
;
1740 return VM_FAULT_SIGBUS
;
1744 * Umm, take care of errors if the page isn't up-to-date.
1745 * Try to re-read it _once_. We do this synchronously,
1746 * because there really aren't any performance issues here
1747 * and we need to check for errors.
1749 ClearPageError(page
);
1750 error
= mapping
->a_ops
->readpage(file
, page
);
1752 wait_on_page_locked(page
);
1753 if (!PageUptodate(page
))
1756 page_cache_release(page
);
1758 if (!error
|| error
== AOP_TRUNCATED_PAGE
)
1761 /* Things didn't work out. Return zero to tell the mm layer so. */
1762 shrink_readahead_size_eio(file
, ra
);
1763 return VM_FAULT_SIGBUS
;
1765 EXPORT_SYMBOL(filemap_fault
);
1767 const struct vm_operations_struct generic_file_vm_ops
= {
1768 .fault
= filemap_fault
,
1771 /* This is used for a general mmap of a disk file */
1773 int generic_file_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1775 struct address_space
*mapping
= file
->f_mapping
;
1777 if (!mapping
->a_ops
->readpage
)
1779 file_accessed(file
);
1780 vma
->vm_ops
= &generic_file_vm_ops
;
1781 vma
->vm_flags
|= VM_CAN_NONLINEAR
;
1786 * This is for filesystems which do not implement ->writepage.
1788 int generic_file_readonly_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1790 if ((vma
->vm_flags
& VM_SHARED
) && (vma
->vm_flags
& VM_MAYWRITE
))
1792 return generic_file_mmap(file
, vma
);
1795 int generic_file_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1799 int generic_file_readonly_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1803 #endif /* CONFIG_MMU */
1805 EXPORT_SYMBOL(generic_file_mmap
);
1806 EXPORT_SYMBOL(generic_file_readonly_mmap
);
1808 static struct page
*__read_cache_page(struct address_space
*mapping
,
1810 int (*filler
)(void *, struct page
*),
1817 page
= find_get_page(mapping
, index
);
1819 page
= __page_cache_alloc(gfp
| __GFP_COLD
);
1821 return ERR_PTR(-ENOMEM
);
1822 err
= add_to_page_cache_lru(page
, mapping
, index
, GFP_KERNEL
);
1823 if (unlikely(err
)) {
1824 page_cache_release(page
);
1827 /* Presumably ENOMEM for radix tree node */
1828 return ERR_PTR(err
);
1830 err
= filler(data
, page
);
1832 page_cache_release(page
);
1833 page
= ERR_PTR(err
);
1839 static struct page
*do_read_cache_page(struct address_space
*mapping
,
1841 int (*filler
)(void *, struct page
*),
1850 page
= __read_cache_page(mapping
, index
, filler
, data
, gfp
);
1853 if (PageUptodate(page
))
1857 if (!page
->mapping
) {
1859 page_cache_release(page
);
1862 if (PageUptodate(page
)) {
1866 err
= filler(data
, page
);
1868 page_cache_release(page
);
1869 return ERR_PTR(err
);
1872 mark_page_accessed(page
);
1877 * read_cache_page_async - read into page cache, fill it if needed
1878 * @mapping: the page's address_space
1879 * @index: the page index
1880 * @filler: function to perform the read
1881 * @data: first arg to filler(data, page) function, often left as NULL
1883 * Same as read_cache_page, but don't wait for page to become unlocked
1884 * after submitting it to the filler.
1886 * Read into the page cache. If a page already exists, and PageUptodate() is
1887 * not set, try to fill the page but don't wait for it to become unlocked.
1889 * If the page does not get brought uptodate, return -EIO.
1891 struct page
*read_cache_page_async(struct address_space
*mapping
,
1893 int (*filler
)(void *, struct page
*),
1896 return do_read_cache_page(mapping
, index
, filler
, data
, mapping_gfp_mask(mapping
));
1898 EXPORT_SYMBOL(read_cache_page_async
);
1900 static struct page
*wait_on_page_read(struct page
*page
)
1902 if (!IS_ERR(page
)) {
1903 wait_on_page_locked(page
);
1904 if (!PageUptodate(page
)) {
1905 page_cache_release(page
);
1906 page
= ERR_PTR(-EIO
);
1913 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
1914 * @mapping: the page's address_space
1915 * @index: the page index
1916 * @gfp: the page allocator flags to use if allocating
1918 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
1919 * any new page allocations done using the specified allocation flags. Note
1920 * that the Radix tree operations will still use GFP_KERNEL, so you can't
1921 * expect to do this atomically or anything like that - but you can pass in
1922 * other page requirements.
1924 * If the page does not get brought uptodate, return -EIO.
1926 struct page
*read_cache_page_gfp(struct address_space
*mapping
,
1930 filler_t
*filler
= (filler_t
*)mapping
->a_ops
->readpage
;
1932 return wait_on_page_read(do_read_cache_page(mapping
, index
, filler
, NULL
, gfp
));
1934 EXPORT_SYMBOL(read_cache_page_gfp
);
1937 * read_cache_page - read into page cache, fill it if needed
1938 * @mapping: the page's address_space
1939 * @index: the page index
1940 * @filler: function to perform the read
1941 * @data: first arg to filler(data, page) function, often left as NULL
1943 * Read into the page cache. If a page already exists, and PageUptodate() is
1944 * not set, try to fill the page then wait for it to become unlocked.
1946 * If the page does not get brought uptodate, return -EIO.
1948 struct page
*read_cache_page(struct address_space
*mapping
,
1950 int (*filler
)(void *, struct page
*),
1953 return wait_on_page_read(read_cache_page_async(mapping
, index
, filler
, data
));
1955 EXPORT_SYMBOL(read_cache_page
);
1958 * The logic we want is
1960 * if suid or (sgid and xgrp)
1963 int should_remove_suid(struct dentry
*dentry
)
1965 mode_t mode
= dentry
->d_inode
->i_mode
;
1968 /* suid always must be killed */
1969 if (unlikely(mode
& S_ISUID
))
1970 kill
= ATTR_KILL_SUID
;
1973 * sgid without any exec bits is just a mandatory locking mark; leave
1974 * it alone. If some exec bits are set, it's a real sgid; kill it.
1976 if (unlikely((mode
& S_ISGID
) && (mode
& S_IXGRP
)))
1977 kill
|= ATTR_KILL_SGID
;
1979 if (unlikely(kill
&& !capable(CAP_FSETID
) && S_ISREG(mode
)))
1984 EXPORT_SYMBOL(should_remove_suid
);
1986 static int __remove_suid(struct dentry
*dentry
, int kill
)
1988 struct iattr newattrs
;
1990 newattrs
.ia_valid
= ATTR_FORCE
| kill
;
1991 return notify_change(dentry
, &newattrs
);
1994 int file_remove_suid(struct file
*file
)
1996 struct dentry
*dentry
= file
->f_path
.dentry
;
1997 struct inode
*inode
= dentry
->d_inode
;
2002 /* Fast path for nothing security related */
2003 if (IS_NOSEC(inode
))
2006 killsuid
= should_remove_suid(dentry
);
2007 killpriv
= security_inode_need_killpriv(dentry
);
2012 error
= security_inode_killpriv(dentry
);
2013 if (!error
&& killsuid
)
2014 error
= __remove_suid(dentry
, killsuid
);
2015 if (!error
&& (inode
->i_sb
->s_flags
& MS_NOSEC
))
2016 inode
->i_flags
|= S_NOSEC
;
2020 EXPORT_SYMBOL(file_remove_suid
);
2022 static size_t __iovec_copy_from_user_inatomic(char *vaddr
,
2023 const struct iovec
*iov
, size_t base
, size_t bytes
)
2025 size_t copied
= 0, left
= 0;
2028 char __user
*buf
= iov
->iov_base
+ base
;
2029 int copy
= min(bytes
, iov
->iov_len
- base
);
2032 left
= __copy_from_user_inatomic(vaddr
, buf
, copy
);
2041 return copied
- left
;
2045 * Copy as much as we can into the page and return the number of bytes which
2046 * were successfully copied. If a fault is encountered then return the number of
2047 * bytes which were copied.
2049 size_t iov_iter_copy_from_user_atomic(struct page
*page
,
2050 struct iov_iter
*i
, unsigned long offset
, size_t bytes
)
2055 BUG_ON(!in_atomic());
2056 kaddr
= kmap_atomic(page
, KM_USER0
);
2057 if (likely(i
->nr_segs
== 1)) {
2059 char __user
*buf
= i
->iov
->iov_base
+ i
->iov_offset
;
2060 left
= __copy_from_user_inatomic(kaddr
+ offset
, buf
, bytes
);
2061 copied
= bytes
- left
;
2063 copied
= __iovec_copy_from_user_inatomic(kaddr
+ offset
,
2064 i
->iov
, i
->iov_offset
, bytes
);
2066 kunmap_atomic(kaddr
, KM_USER0
);
2070 EXPORT_SYMBOL(iov_iter_copy_from_user_atomic
);
2073 * This has the same sideeffects and return value as
2074 * iov_iter_copy_from_user_atomic().
2075 * The difference is that it attempts to resolve faults.
2076 * Page must not be locked.
2078 size_t iov_iter_copy_from_user(struct page
*page
,
2079 struct iov_iter
*i
, unsigned long offset
, size_t bytes
)
2085 if (likely(i
->nr_segs
== 1)) {
2087 char __user
*buf
= i
->iov
->iov_base
+ i
->iov_offset
;
2088 left
= __copy_from_user(kaddr
+ offset
, buf
, bytes
);
2089 copied
= bytes
- left
;
2091 copied
= __iovec_copy_from_user_inatomic(kaddr
+ offset
,
2092 i
->iov
, i
->iov_offset
, bytes
);
2097 EXPORT_SYMBOL(iov_iter_copy_from_user
);
2099 void iov_iter_advance(struct iov_iter
*i
, size_t bytes
)
2101 BUG_ON(i
->count
< bytes
);
2103 if (likely(i
->nr_segs
== 1)) {
2104 i
->iov_offset
+= bytes
;
2107 const struct iovec
*iov
= i
->iov
;
2108 size_t base
= i
->iov_offset
;
2111 * The !iov->iov_len check ensures we skip over unlikely
2112 * zero-length segments (without overruning the iovec).
2114 while (bytes
|| unlikely(i
->count
&& !iov
->iov_len
)) {
2117 copy
= min(bytes
, iov
->iov_len
- base
);
2118 BUG_ON(!i
->count
|| i
->count
< copy
);
2122 if (iov
->iov_len
== base
) {
2128 i
->iov_offset
= base
;
2131 EXPORT_SYMBOL(iov_iter_advance
);
2134 * Fault in the first iovec of the given iov_iter, to a maximum length
2135 * of bytes. Returns 0 on success, or non-zero if the memory could not be
2136 * accessed (ie. because it is an invalid address).
2138 * writev-intensive code may want this to prefault several iovecs -- that
2139 * would be possible (callers must not rely on the fact that _only_ the
2140 * first iovec will be faulted with the current implementation).
2142 int iov_iter_fault_in_readable(struct iov_iter
*i
, size_t bytes
)
2144 char __user
*buf
= i
->iov
->iov_base
+ i
->iov_offset
;
2145 bytes
= min(bytes
, i
->iov
->iov_len
- i
->iov_offset
);
2146 return fault_in_pages_readable(buf
, bytes
);
2148 EXPORT_SYMBOL(iov_iter_fault_in_readable
);
2151 * Return the count of just the current iov_iter segment.
2153 size_t iov_iter_single_seg_count(struct iov_iter
*i
)
2155 const struct iovec
*iov
= i
->iov
;
2156 if (i
->nr_segs
== 1)
2159 return min(i
->count
, iov
->iov_len
- i
->iov_offset
);
2161 EXPORT_SYMBOL(iov_iter_single_seg_count
);
2164 * Performs necessary checks before doing a write
2166 * Can adjust writing position or amount of bytes to write.
2167 * Returns appropriate error code that caller should return or
2168 * zero in case that write should be allowed.
2170 inline int generic_write_checks(struct file
*file
, loff_t
*pos
, size_t *count
, int isblk
)
2172 struct inode
*inode
= file
->f_mapping
->host
;
2173 unsigned long limit
= rlimit(RLIMIT_FSIZE
);
2175 if (unlikely(*pos
< 0))
2179 /* FIXME: this is for backwards compatibility with 2.4 */
2180 if (file
->f_flags
& O_APPEND
)
2181 *pos
= i_size_read(inode
);
2183 if (limit
!= RLIM_INFINITY
) {
2184 if (*pos
>= limit
) {
2185 send_sig(SIGXFSZ
, current
, 0);
2188 if (*count
> limit
- (typeof(limit
))*pos
) {
2189 *count
= limit
- (typeof(limit
))*pos
;
2197 if (unlikely(*pos
+ *count
> MAX_NON_LFS
&&
2198 !(file
->f_flags
& O_LARGEFILE
))) {
2199 if (*pos
>= MAX_NON_LFS
) {
2202 if (*count
> MAX_NON_LFS
- (unsigned long)*pos
) {
2203 *count
= MAX_NON_LFS
- (unsigned long)*pos
;
2208 * Are we about to exceed the fs block limit ?
2210 * If we have written data it becomes a short write. If we have
2211 * exceeded without writing data we send a signal and return EFBIG.
2212 * Linus frestrict idea will clean these up nicely..
2214 if (likely(!isblk
)) {
2215 if (unlikely(*pos
>= inode
->i_sb
->s_maxbytes
)) {
2216 if (*count
|| *pos
> inode
->i_sb
->s_maxbytes
) {
2219 /* zero-length writes at ->s_maxbytes are OK */
2222 if (unlikely(*pos
+ *count
> inode
->i_sb
->s_maxbytes
))
2223 *count
= inode
->i_sb
->s_maxbytes
- *pos
;
2227 if (bdev_read_only(I_BDEV(inode
)))
2229 isize
= i_size_read(inode
);
2230 if (*pos
>= isize
) {
2231 if (*count
|| *pos
> isize
)
2235 if (*pos
+ *count
> isize
)
2236 *count
= isize
- *pos
;
2243 EXPORT_SYMBOL(generic_write_checks
);
2245 int pagecache_write_begin(struct file
*file
, struct address_space
*mapping
,
2246 loff_t pos
, unsigned len
, unsigned flags
,
2247 struct page
**pagep
, void **fsdata
)
2249 const struct address_space_operations
*aops
= mapping
->a_ops
;
2251 return aops
->write_begin(file
, mapping
, pos
, len
, flags
,
2254 EXPORT_SYMBOL(pagecache_write_begin
);
2256 int pagecache_write_end(struct file
*file
, struct address_space
*mapping
,
2257 loff_t pos
, unsigned len
, unsigned copied
,
2258 struct page
*page
, void *fsdata
)
2260 const struct address_space_operations
*aops
= mapping
->a_ops
;
2262 mark_page_accessed(page
);
2263 return aops
->write_end(file
, mapping
, pos
, len
, copied
, page
, fsdata
);
2265 EXPORT_SYMBOL(pagecache_write_end
);
2268 generic_file_direct_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2269 unsigned long *nr_segs
, loff_t pos
, loff_t
*ppos
,
2270 size_t count
, size_t ocount
)
2272 struct file
*file
= iocb
->ki_filp
;
2273 struct address_space
*mapping
= file
->f_mapping
;
2274 struct inode
*inode
= mapping
->host
;
2279 if (count
!= ocount
)
2280 *nr_segs
= iov_shorten((struct iovec
*)iov
, *nr_segs
, count
);
2282 write_len
= iov_length(iov
, *nr_segs
);
2283 end
= (pos
+ write_len
- 1) >> PAGE_CACHE_SHIFT
;
2285 written
= filemap_write_and_wait_range(mapping
, pos
, pos
+ write_len
- 1);
2290 * After a write we want buffered reads to be sure to go to disk to get
2291 * the new data. We invalidate clean cached page from the region we're
2292 * about to write. We do this *before* the write so that we can return
2293 * without clobbering -EIOCBQUEUED from ->direct_IO().
2295 if (mapping
->nrpages
) {
2296 written
= invalidate_inode_pages2_range(mapping
,
2297 pos
>> PAGE_CACHE_SHIFT
, end
);
2299 * If a page can not be invalidated, return 0 to fall back
2300 * to buffered write.
2303 if (written
== -EBUSY
)
2309 written
= mapping
->a_ops
->direct_IO(WRITE
, iocb
, iov
, pos
, *nr_segs
);
2312 * Finally, try again to invalidate clean pages which might have been
2313 * cached by non-direct readahead, or faulted in by get_user_pages()
2314 * if the source of the write was an mmap'ed region of the file
2315 * we're writing. Either one is a pretty crazy thing to do,
2316 * so we don't support it 100%. If this invalidation
2317 * fails, tough, the write still worked...
2319 if (mapping
->nrpages
) {
2320 invalidate_inode_pages2_range(mapping
,
2321 pos
>> PAGE_CACHE_SHIFT
, end
);
2326 if (pos
> i_size_read(inode
) && !S_ISBLK(inode
->i_mode
)) {
2327 i_size_write(inode
, pos
);
2328 mark_inode_dirty(inode
);
2335 EXPORT_SYMBOL(generic_file_direct_write
);
2338 * Find or create a page at the given pagecache position. Return the locked
2339 * page. This function is specifically for buffered writes.
2341 struct page
*grab_cache_page_write_begin(struct address_space
*mapping
,
2342 pgoff_t index
, unsigned flags
)
2346 gfp_t gfp_notmask
= 0;
2347 if (flags
& AOP_FLAG_NOFS
)
2348 gfp_notmask
= __GFP_FS
;
2350 page
= find_lock_page(mapping
, index
);
2354 page
= __page_cache_alloc(mapping_gfp_mask(mapping
) & ~gfp_notmask
);
2357 status
= add_to_page_cache_lru(page
, mapping
, index
,
2358 GFP_KERNEL
& ~gfp_notmask
);
2359 if (unlikely(status
)) {
2360 page_cache_release(page
);
2361 if (status
== -EEXIST
)
2366 wait_on_page_writeback(page
);
2369 EXPORT_SYMBOL(grab_cache_page_write_begin
);
2371 static ssize_t
generic_perform_write(struct file
*file
,
2372 struct iov_iter
*i
, loff_t pos
)
2374 struct address_space
*mapping
= file
->f_mapping
;
2375 const struct address_space_operations
*a_ops
= mapping
->a_ops
;
2377 ssize_t written
= 0;
2378 unsigned int flags
= 0;
2381 * Copies from kernel address space cannot fail (NFSD is a big user).
2383 if (segment_eq(get_fs(), KERNEL_DS
))
2384 flags
|= AOP_FLAG_UNINTERRUPTIBLE
;
2388 unsigned long offset
; /* Offset into pagecache page */
2389 unsigned long bytes
; /* Bytes to write to page */
2390 size_t copied
; /* Bytes copied from user */
2393 offset
= (pos
& (PAGE_CACHE_SIZE
- 1));
2394 bytes
= min_t(unsigned long, PAGE_CACHE_SIZE
- offset
,
2400 * Bring in the user page that we will copy from _first_.
2401 * Otherwise there's a nasty deadlock on copying from the
2402 * same page as we're writing to, without it being marked
2405 * Not only is this an optimisation, but it is also required
2406 * to check that the address is actually valid, when atomic
2407 * usercopies are used, below.
2409 if (unlikely(iov_iter_fault_in_readable(i
, bytes
))) {
2414 status
= a_ops
->write_begin(file
, mapping
, pos
, bytes
, flags
,
2416 if (unlikely(status
))
2419 if (mapping_writably_mapped(mapping
))
2420 flush_dcache_page(page
);
2422 pagefault_disable();
2423 copied
= iov_iter_copy_from_user_atomic(page
, i
, offset
, bytes
);
2425 flush_dcache_page(page
);
2427 mark_page_accessed(page
);
2428 status
= a_ops
->write_end(file
, mapping
, pos
, bytes
, copied
,
2430 if (unlikely(status
< 0))
2436 iov_iter_advance(i
, copied
);
2437 if (unlikely(copied
== 0)) {
2439 * If we were unable to copy any data at all, we must
2440 * fall back to a single segment length write.
2442 * If we didn't fallback here, we could livelock
2443 * because not all segments in the iov can be copied at
2444 * once without a pagefault.
2446 bytes
= min_t(unsigned long, PAGE_CACHE_SIZE
- offset
,
2447 iov_iter_single_seg_count(i
));
2453 balance_dirty_pages_ratelimited(mapping
);
2455 } while (iov_iter_count(i
));
2457 return written
? written
: status
;
2461 generic_file_buffered_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2462 unsigned long nr_segs
, loff_t pos
, loff_t
*ppos
,
2463 size_t count
, ssize_t written
)
2465 struct file
*file
= iocb
->ki_filp
;
2469 iov_iter_init(&i
, iov
, nr_segs
, count
, written
);
2470 status
= generic_perform_write(file
, &i
, pos
);
2472 if (likely(status
>= 0)) {
2474 *ppos
= pos
+ status
;
2477 return written
? written
: status
;
2479 EXPORT_SYMBOL(generic_file_buffered_write
);
2482 * __generic_file_aio_write - write data to a file
2483 * @iocb: IO state structure (file, offset, etc.)
2484 * @iov: vector with data to write
2485 * @nr_segs: number of segments in the vector
2486 * @ppos: position where to write
2488 * This function does all the work needed for actually writing data to a
2489 * file. It does all basic checks, removes SUID from the file, updates
2490 * modification times and calls proper subroutines depending on whether we
2491 * do direct IO or a standard buffered write.
2493 * It expects i_mutex to be grabbed unless we work on a block device or similar
2494 * object which does not need locking at all.
2496 * This function does *not* take care of syncing data in case of O_SYNC write.
2497 * A caller has to handle it. This is mainly due to the fact that we want to
2498 * avoid syncing under i_mutex.
2500 ssize_t
__generic_file_aio_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2501 unsigned long nr_segs
, loff_t
*ppos
)
2503 struct file
*file
= iocb
->ki_filp
;
2504 struct address_space
* mapping
= file
->f_mapping
;
2505 size_t ocount
; /* original count */
2506 size_t count
; /* after file limit checks */
2507 struct inode
*inode
= mapping
->host
;
2513 err
= generic_segment_checks(iov
, &nr_segs
, &ocount
, VERIFY_READ
);
2520 vfs_check_frozen(inode
->i_sb
, SB_FREEZE_WRITE
);
2522 /* We can write back this queue in page reclaim */
2523 current
->backing_dev_info
= mapping
->backing_dev_info
;
2526 err
= generic_write_checks(file
, &pos
, &count
, S_ISBLK(inode
->i_mode
));
2533 err
= file_remove_suid(file
);
2537 file_update_time(file
);
2539 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2540 if (unlikely(file
->f_flags
& O_DIRECT
)) {
2542 ssize_t written_buffered
;
2544 written
= generic_file_direct_write(iocb
, iov
, &nr_segs
, pos
,
2545 ppos
, count
, ocount
);
2546 if (written
< 0 || written
== count
)
2549 * direct-io write to a hole: fall through to buffered I/O
2550 * for completing the rest of the request.
2554 written_buffered
= generic_file_buffered_write(iocb
, iov
,
2555 nr_segs
, pos
, ppos
, count
,
2558 * If generic_file_buffered_write() retuned a synchronous error
2559 * then we want to return the number of bytes which were
2560 * direct-written, or the error code if that was zero. Note
2561 * that this differs from normal direct-io semantics, which
2562 * will return -EFOO even if some bytes were written.
2564 if (written_buffered
< 0) {
2565 err
= written_buffered
;
2570 * We need to ensure that the page cache pages are written to
2571 * disk and invalidated to preserve the expected O_DIRECT
2574 endbyte
= pos
+ written_buffered
- written
- 1;
2575 err
= filemap_write_and_wait_range(file
->f_mapping
, pos
, endbyte
);
2577 written
= written_buffered
;
2578 invalidate_mapping_pages(mapping
,
2579 pos
>> PAGE_CACHE_SHIFT
,
2580 endbyte
>> PAGE_CACHE_SHIFT
);
2583 * We don't know how much we wrote, so just return
2584 * the number of bytes which were direct-written
2588 written
= generic_file_buffered_write(iocb
, iov
, nr_segs
,
2589 pos
, ppos
, count
, written
);
2592 current
->backing_dev_info
= NULL
;
2593 return written
? written
: err
;
2595 EXPORT_SYMBOL(__generic_file_aio_write
);
2598 * generic_file_aio_write - write data to a file
2599 * @iocb: IO state structure
2600 * @iov: vector with data to write
2601 * @nr_segs: number of segments in the vector
2602 * @pos: position in file where to write
2604 * This is a wrapper around __generic_file_aio_write() to be used by most
2605 * filesystems. It takes care of syncing the file in case of O_SYNC file
2606 * and acquires i_mutex as needed.
2608 ssize_t
generic_file_aio_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2609 unsigned long nr_segs
, loff_t pos
)
2611 struct file
*file
= iocb
->ki_filp
;
2612 struct inode
*inode
= file
->f_mapping
->host
;
2613 struct blk_plug plug
;
2616 BUG_ON(iocb
->ki_pos
!= pos
);
2618 mutex_lock(&inode
->i_mutex
);
2619 blk_start_plug(&plug
);
2620 ret
= __generic_file_aio_write(iocb
, iov
, nr_segs
, &iocb
->ki_pos
);
2621 mutex_unlock(&inode
->i_mutex
);
2623 if (ret
> 0 || ret
== -EIOCBQUEUED
) {
2626 err
= generic_write_sync(file
, pos
, ret
);
2627 if (err
< 0 && ret
> 0)
2630 blk_finish_plug(&plug
);
2633 EXPORT_SYMBOL(generic_file_aio_write
);
2636 * try_to_release_page() - release old fs-specific metadata on a page
2638 * @page: the page which the kernel is trying to free
2639 * @gfp_mask: memory allocation flags (and I/O mode)
2641 * The address_space is to try to release any data against the page
2642 * (presumably at page->private). If the release was successful, return `1'.
2643 * Otherwise return zero.
2645 * This may also be called if PG_fscache is set on a page, indicating that the
2646 * page is known to the local caching routines.
2648 * The @gfp_mask argument specifies whether I/O may be performed to release
2649 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
2652 int try_to_release_page(struct page
*page
, gfp_t gfp_mask
)
2654 struct address_space
* const mapping
= page
->mapping
;
2656 BUG_ON(!PageLocked(page
));
2657 if (PageWriteback(page
))
2660 if (mapping
&& mapping
->a_ops
->releasepage
)
2661 return mapping
->a_ops
->releasepage(page
, gfp_mask
);
2662 return try_to_free_buffers(page
);
2665 EXPORT_SYMBOL(try_to_release_page
);