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/config.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/compiler.h>
17 #include <linux/uaccess.h>
18 #include <linux/aio.h>
19 #include <linux/capability.h>
20 #include <linux/kernel_stat.h>
22 #include <linux/swap.h>
23 #include <linux/mman.h>
24 #include <linux/pagemap.h>
25 #include <linux/file.h>
26 #include <linux/uio.h>
27 #include <linux/hash.h>
28 #include <linux/writeback.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>
38 * FIXME: remove all knowledge of the buffer layer from the core VM
40 #include <linux/buffer_head.h> /* for generic_osync_inode */
45 generic_file_direct_IO(int rw
, struct kiocb
*iocb
, const struct iovec
*iov
,
46 loff_t offset
, unsigned long nr_segs
);
49 * Shared mappings implemented 30.11.1994. It's not fully working yet,
52 * Shared mappings now work. 15.8.1995 Bruno.
54 * finished 'unifying' the page and buffer cache and SMP-threaded the
55 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
57 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
63 * ->i_mmap_lock (vmtruncate)
64 * ->private_lock (__free_pte->__set_page_dirty_buffers)
65 * ->swap_lock (exclusive_swap_page, others)
66 * ->mapping->tree_lock
69 * ->i_mmap_lock (truncate->unmap_mapping_range)
73 * ->page_table_lock or pte_lock (various, mainly in memory.c)
74 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
77 * ->lock_page (access_process_vm)
83 * ->i_alloc_sem (various)
86 * ->sb_lock (fs/fs-writeback.c)
87 * ->mapping->tree_lock (__sync_single_inode)
90 * ->anon_vma.lock (vma_adjust)
93 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
95 * ->page_table_lock or pte_lock
96 * ->swap_lock (try_to_unmap_one)
97 * ->private_lock (try_to_unmap_one)
98 * ->tree_lock (try_to_unmap_one)
99 * ->zone.lru_lock (follow_page->mark_page_accessed)
100 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
101 * ->private_lock (page_remove_rmap->set_page_dirty)
102 * ->tree_lock (page_remove_rmap->set_page_dirty)
103 * ->inode_lock (page_remove_rmap->set_page_dirty)
104 * ->inode_lock (zap_pte_range->set_page_dirty)
105 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
108 * ->dcache_lock (proc_pid_lookup)
112 * Remove a page from the page cache and free it. Caller has to make
113 * sure the page is locked and that nobody else uses it - or that usage
114 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
116 void __remove_from_page_cache(struct page
*page
)
118 struct address_space
*mapping
= page
->mapping
;
120 radix_tree_delete(&mapping
->page_tree
, page
->index
);
121 page
->mapping
= NULL
;
126 void remove_from_page_cache(struct page
*page
)
128 struct address_space
*mapping
= page
->mapping
;
130 BUG_ON(!PageLocked(page
));
132 write_lock_irq(&mapping
->tree_lock
);
133 __remove_from_page_cache(page
);
134 write_unlock_irq(&mapping
->tree_lock
);
137 static int sync_page(void *word
)
139 struct address_space
*mapping
;
142 page
= container_of((unsigned long *)word
, struct page
, flags
);
145 * page_mapping() is being called without PG_locked held.
146 * Some knowledge of the state and use of the page is used to
147 * reduce the requirements down to a memory barrier.
148 * The danger here is of a stale page_mapping() return value
149 * indicating a struct address_space different from the one it's
150 * associated with when it is associated with one.
151 * After smp_mb(), it's either the correct page_mapping() for
152 * the page, or an old page_mapping() and the page's own
153 * page_mapping() has gone NULL.
154 * The ->sync_page() address_space operation must tolerate
155 * page_mapping() going NULL. By an amazing coincidence,
156 * this comes about because none of the users of the page
157 * in the ->sync_page() methods make essential use of the
158 * page_mapping(), merely passing the page down to the backing
159 * device's unplug functions when it's non-NULL, which in turn
160 * ignore it for all cases but swap, where only page_private(page) is
161 * of interest. When page_mapping() does go NULL, the entire
162 * call stack gracefully ignores the page and returns.
166 mapping
= page_mapping(page
);
167 if (mapping
&& mapping
->a_ops
&& mapping
->a_ops
->sync_page
)
168 mapping
->a_ops
->sync_page(page
);
174 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
175 * @mapping: address space structure to write
176 * @start: offset in bytes where the range starts
177 * @end: offset in bytes where the range ends (inclusive)
178 * @sync_mode: enable synchronous operation
180 * Start writeback against all of a mapping's dirty pages that lie
181 * within the byte offsets <start, end> inclusive.
183 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
184 * opposed to a regular memory cleansing writeback. The difference between
185 * these two operations is that if a dirty page/buffer is encountered, it must
186 * be waited upon, and not just skipped over.
188 int __filemap_fdatawrite_range(struct address_space
*mapping
, loff_t start
,
189 loff_t end
, int sync_mode
)
192 struct writeback_control wbc
= {
193 .sync_mode
= sync_mode
,
194 .nr_to_write
= mapping
->nrpages
* 2,
195 .range_start
= start
,
199 if (!mapping_cap_writeback_dirty(mapping
))
202 ret
= do_writepages(mapping
, &wbc
);
206 static inline int __filemap_fdatawrite(struct address_space
*mapping
,
209 return __filemap_fdatawrite_range(mapping
, 0, LLONG_MAX
, sync_mode
);
212 int filemap_fdatawrite(struct address_space
*mapping
)
214 return __filemap_fdatawrite(mapping
, WB_SYNC_ALL
);
216 EXPORT_SYMBOL(filemap_fdatawrite
);
218 static int filemap_fdatawrite_range(struct address_space
*mapping
, loff_t start
,
221 return __filemap_fdatawrite_range(mapping
, start
, end
, WB_SYNC_ALL
);
225 * filemap_flush - mostly a non-blocking flush
226 * @mapping: target address_space
228 * This is a mostly non-blocking flush. Not suitable for data-integrity
229 * purposes - I/O may not be started against all dirty pages.
231 int filemap_flush(struct address_space
*mapping
)
233 return __filemap_fdatawrite(mapping
, WB_SYNC_NONE
);
235 EXPORT_SYMBOL(filemap_flush
);
238 * wait_on_page_writeback_range - wait for writeback to complete
239 * @mapping: target address_space
240 * @start: beginning page index
241 * @end: ending page index
243 * Wait for writeback to complete against pages indexed by start->end
246 int wait_on_page_writeback_range(struct address_space
*mapping
,
247 pgoff_t start
, pgoff_t end
)
257 pagevec_init(&pvec
, 0);
259 while ((index
<= end
) &&
260 (nr_pages
= pagevec_lookup_tag(&pvec
, mapping
, &index
,
261 PAGECACHE_TAG_WRITEBACK
,
262 min(end
- index
, (pgoff_t
)PAGEVEC_SIZE
-1) + 1)) != 0) {
265 for (i
= 0; i
< nr_pages
; i
++) {
266 struct page
*page
= pvec
.pages
[i
];
268 /* until radix tree lookup accepts end_index */
269 if (page
->index
> end
)
272 wait_on_page_writeback(page
);
276 pagevec_release(&pvec
);
280 /* Check for outstanding write errors */
281 if (test_and_clear_bit(AS_ENOSPC
, &mapping
->flags
))
283 if (test_and_clear_bit(AS_EIO
, &mapping
->flags
))
290 * sync_page_range - write and wait on all pages in the passed range
291 * @inode: target inode
292 * @mapping: target address_space
293 * @pos: beginning offset in pages to write
294 * @count: number of bytes to write
296 * Write and wait upon all the pages in the passed range. This is a "data
297 * integrity" operation. It waits upon in-flight writeout before starting and
298 * waiting upon new writeout. If there was an IO error, return it.
300 * We need to re-take i_mutex during the generic_osync_inode list walk because
301 * it is otherwise livelockable.
303 int sync_page_range(struct inode
*inode
, struct address_space
*mapping
,
304 loff_t pos
, loff_t count
)
306 pgoff_t start
= pos
>> PAGE_CACHE_SHIFT
;
307 pgoff_t end
= (pos
+ count
- 1) >> PAGE_CACHE_SHIFT
;
310 if (!mapping_cap_writeback_dirty(mapping
) || !count
)
312 ret
= filemap_fdatawrite_range(mapping
, pos
, pos
+ count
- 1);
314 mutex_lock(&inode
->i_mutex
);
315 ret
= generic_osync_inode(inode
, mapping
, OSYNC_METADATA
);
316 mutex_unlock(&inode
->i_mutex
);
319 ret
= wait_on_page_writeback_range(mapping
, start
, end
);
322 EXPORT_SYMBOL(sync_page_range
);
325 * sync_page_range_nolock
326 * @inode: target inode
327 * @mapping: target address_space
328 * @pos: beginning offset in pages to write
329 * @count: number of bytes to write
331 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
332 * as it forces O_SYNC writers to different parts of the same file
333 * to be serialised right until io completion.
335 int sync_page_range_nolock(struct inode
*inode
, struct address_space
*mapping
,
336 loff_t pos
, loff_t count
)
338 pgoff_t start
= pos
>> PAGE_CACHE_SHIFT
;
339 pgoff_t end
= (pos
+ count
- 1) >> PAGE_CACHE_SHIFT
;
342 if (!mapping_cap_writeback_dirty(mapping
) || !count
)
344 ret
= filemap_fdatawrite_range(mapping
, pos
, pos
+ count
- 1);
346 ret
= generic_osync_inode(inode
, mapping
, OSYNC_METADATA
);
348 ret
= wait_on_page_writeback_range(mapping
, start
, end
);
351 EXPORT_SYMBOL(sync_page_range_nolock
);
354 * filemap_fdatawait - wait for all under-writeback pages to complete
355 * @mapping: address space structure to wait for
357 * Walk the list of under-writeback pages of the given address space
358 * and wait for all of them.
360 int filemap_fdatawait(struct address_space
*mapping
)
362 loff_t i_size
= i_size_read(mapping
->host
);
367 return wait_on_page_writeback_range(mapping
, 0,
368 (i_size
- 1) >> PAGE_CACHE_SHIFT
);
370 EXPORT_SYMBOL(filemap_fdatawait
);
372 int filemap_write_and_wait(struct address_space
*mapping
)
376 if (mapping
->nrpages
) {
377 err
= filemap_fdatawrite(mapping
);
379 * Even if the above returned error, the pages may be
380 * written partially (e.g. -ENOSPC), so we wait for it.
381 * But the -EIO is special case, it may indicate the worst
382 * thing (e.g. bug) happened, so we avoid waiting for it.
385 int err2
= filemap_fdatawait(mapping
);
392 EXPORT_SYMBOL(filemap_write_and_wait
);
395 * filemap_write_and_wait_range - write out & wait on a file range
396 * @mapping: the address_space for the pages
397 * @lstart: offset in bytes where the range starts
398 * @lend: offset in bytes where the range ends (inclusive)
400 * Write out and wait upon file offsets lstart->lend, inclusive.
402 * Note that `lend' is inclusive (describes the last byte to be written) so
403 * that this function can be used to write to the very end-of-file (end = -1).
405 int filemap_write_and_wait_range(struct address_space
*mapping
,
406 loff_t lstart
, loff_t lend
)
410 if (mapping
->nrpages
) {
411 err
= __filemap_fdatawrite_range(mapping
, lstart
, lend
,
413 /* See comment of filemap_write_and_wait() */
415 int err2
= wait_on_page_writeback_range(mapping
,
416 lstart
>> PAGE_CACHE_SHIFT
,
417 lend
>> PAGE_CACHE_SHIFT
);
426 * add_to_page_cache - add newly allocated pagecache pages
428 * @mapping: the page's address_space
429 * @offset: page index
430 * @gfp_mask: page allocation mode
432 * This function is used to add newly allocated pagecache pages;
433 * the page is new, so we can just run SetPageLocked() against it.
434 * The other page state flags were set by rmqueue().
436 * This function does not add the page to the LRU. The caller must do that.
438 int add_to_page_cache(struct page
*page
, struct address_space
*mapping
,
439 pgoff_t offset
, gfp_t gfp_mask
)
441 int error
= radix_tree_preload(gfp_mask
& ~__GFP_HIGHMEM
);
444 write_lock_irq(&mapping
->tree_lock
);
445 error
= radix_tree_insert(&mapping
->page_tree
, offset
, page
);
447 page_cache_get(page
);
449 page
->mapping
= mapping
;
450 page
->index
= offset
;
454 write_unlock_irq(&mapping
->tree_lock
);
455 radix_tree_preload_end();
459 EXPORT_SYMBOL(add_to_page_cache
);
461 int add_to_page_cache_lru(struct page
*page
, struct address_space
*mapping
,
462 pgoff_t offset
, gfp_t gfp_mask
)
464 int ret
= add_to_page_cache(page
, mapping
, offset
, gfp_mask
);
471 struct page
*page_cache_alloc(struct address_space
*x
)
473 if (cpuset_do_page_mem_spread()) {
474 int n
= cpuset_mem_spread_node();
475 return alloc_pages_node(n
, mapping_gfp_mask(x
), 0);
477 return alloc_pages(mapping_gfp_mask(x
), 0);
479 EXPORT_SYMBOL(page_cache_alloc
);
481 struct page
*page_cache_alloc_cold(struct address_space
*x
)
483 if (cpuset_do_page_mem_spread()) {
484 int n
= cpuset_mem_spread_node();
485 return alloc_pages_node(n
, mapping_gfp_mask(x
)|__GFP_COLD
, 0);
487 return alloc_pages(mapping_gfp_mask(x
)|__GFP_COLD
, 0);
489 EXPORT_SYMBOL(page_cache_alloc_cold
);
493 * In order to wait for pages to become available there must be
494 * waitqueues associated with pages. By using a hash table of
495 * waitqueues where the bucket discipline is to maintain all
496 * waiters on the same queue and wake all when any of the pages
497 * become available, and for the woken contexts to check to be
498 * sure the appropriate page became available, this saves space
499 * at a cost of "thundering herd" phenomena during rare hash
502 static wait_queue_head_t
*page_waitqueue(struct page
*page
)
504 const struct zone
*zone
= page_zone(page
);
506 return &zone
->wait_table
[hash_ptr(page
, zone
->wait_table_bits
)];
509 static inline void wake_up_page(struct page
*page
, int bit
)
511 __wake_up_bit(page_waitqueue(page
), &page
->flags
, bit
);
514 void fastcall
wait_on_page_bit(struct page
*page
, int bit_nr
)
516 DEFINE_WAIT_BIT(wait
, &page
->flags
, bit_nr
);
518 if (test_bit(bit_nr
, &page
->flags
))
519 __wait_on_bit(page_waitqueue(page
), &wait
, sync_page
,
520 TASK_UNINTERRUPTIBLE
);
522 EXPORT_SYMBOL(wait_on_page_bit
);
525 * unlock_page - unlock a locked page
528 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
529 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
530 * mechananism between PageLocked pages and PageWriteback pages is shared.
531 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
533 * The first mb is necessary to safely close the critical section opened by the
534 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
535 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
536 * parallel wait_on_page_locked()).
538 void fastcall
unlock_page(struct page
*page
)
540 smp_mb__before_clear_bit();
541 if (!TestClearPageLocked(page
))
543 smp_mb__after_clear_bit();
544 wake_up_page(page
, PG_locked
);
546 EXPORT_SYMBOL(unlock_page
);
549 * end_page_writeback - end writeback against a page
552 void end_page_writeback(struct page
*page
)
554 if (!TestClearPageReclaim(page
) || rotate_reclaimable_page(page
)) {
555 if (!test_clear_page_writeback(page
))
558 smp_mb__after_clear_bit();
559 wake_up_page(page
, PG_writeback
);
561 EXPORT_SYMBOL(end_page_writeback
);
564 * __lock_page - get a lock on the page, assuming we need to sleep to get it
565 * @page: the page to lock
567 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
568 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
569 * chances are that on the second loop, the block layer's plug list is empty,
570 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
572 void fastcall
__lock_page(struct page
*page
)
574 DEFINE_WAIT_BIT(wait
, &page
->flags
, PG_locked
);
576 __wait_on_bit_lock(page_waitqueue(page
), &wait
, sync_page
,
577 TASK_UNINTERRUPTIBLE
);
579 EXPORT_SYMBOL(__lock_page
);
582 * find_get_page - find and get a page reference
583 * @mapping: the address_space to search
584 * @offset: the page index
586 * A rather lightweight function, finding and getting a reference to a
587 * hashed page atomically.
589 struct page
* find_get_page(struct address_space
*mapping
, unsigned long offset
)
593 read_lock_irq(&mapping
->tree_lock
);
594 page
= radix_tree_lookup(&mapping
->page_tree
, offset
);
596 page_cache_get(page
);
597 read_unlock_irq(&mapping
->tree_lock
);
600 EXPORT_SYMBOL(find_get_page
);
603 * find_trylock_page - find and lock a page
604 * @mapping: the address_space to search
605 * @offset: the page index
607 * Same as find_get_page(), but trylock it instead of incrementing the count.
609 struct page
*find_trylock_page(struct address_space
*mapping
, unsigned long offset
)
613 read_lock_irq(&mapping
->tree_lock
);
614 page
= radix_tree_lookup(&mapping
->page_tree
, offset
);
615 if (page
&& TestSetPageLocked(page
))
617 read_unlock_irq(&mapping
->tree_lock
);
620 EXPORT_SYMBOL(find_trylock_page
);
623 * find_lock_page - locate, pin and lock a pagecache page
624 * @mapping: the address_space to search
625 * @offset: the page index
627 * Locates the desired pagecache page, locks it, increments its reference
628 * count and returns its address.
630 * Returns zero if the page was not present. find_lock_page() may sleep.
632 struct page
*find_lock_page(struct address_space
*mapping
,
633 unsigned long offset
)
637 read_lock_irq(&mapping
->tree_lock
);
639 page
= radix_tree_lookup(&mapping
->page_tree
, offset
);
641 page_cache_get(page
);
642 if (TestSetPageLocked(page
)) {
643 read_unlock_irq(&mapping
->tree_lock
);
645 read_lock_irq(&mapping
->tree_lock
);
647 /* Has the page been truncated while we slept? */
648 if (unlikely(page
->mapping
!= mapping
||
649 page
->index
!= offset
)) {
651 page_cache_release(page
);
656 read_unlock_irq(&mapping
->tree_lock
);
659 EXPORT_SYMBOL(find_lock_page
);
662 * find_or_create_page - locate or add a pagecache page
663 * @mapping: the page's address_space
664 * @index: the page's index into the mapping
665 * @gfp_mask: page allocation mode
667 * Locates a page in the pagecache. If the page is not present, a new page
668 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
669 * LRU list. The returned page is locked and has its reference count
672 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
675 * find_or_create_page() returns the desired page's address, or zero on
678 struct page
*find_or_create_page(struct address_space
*mapping
,
679 unsigned long index
, gfp_t gfp_mask
)
681 struct page
*page
, *cached_page
= NULL
;
684 page
= find_lock_page(mapping
, index
);
687 cached_page
= alloc_page(gfp_mask
);
691 err
= add_to_page_cache_lru(cached_page
, mapping
,
696 } else if (err
== -EEXIST
)
700 page_cache_release(cached_page
);
703 EXPORT_SYMBOL(find_or_create_page
);
706 * find_get_pages - gang pagecache lookup
707 * @mapping: The address_space to search
708 * @start: The starting page index
709 * @nr_pages: The maximum number of pages
710 * @pages: Where the resulting pages are placed
712 * find_get_pages() will search for and return a group of up to
713 * @nr_pages pages in the mapping. The pages are placed at @pages.
714 * find_get_pages() takes a reference against the returned pages.
716 * The search returns a group of mapping-contiguous pages with ascending
717 * indexes. There may be holes in the indices due to not-present pages.
719 * find_get_pages() returns the number of pages which were found.
721 unsigned find_get_pages(struct address_space
*mapping
, pgoff_t start
,
722 unsigned int nr_pages
, struct page
**pages
)
727 read_lock_irq(&mapping
->tree_lock
);
728 ret
= radix_tree_gang_lookup(&mapping
->page_tree
,
729 (void **)pages
, start
, nr_pages
);
730 for (i
= 0; i
< ret
; i
++)
731 page_cache_get(pages
[i
]);
732 read_unlock_irq(&mapping
->tree_lock
);
737 * find_get_pages_contig - gang contiguous pagecache lookup
738 * @mapping: The address_space to search
739 * @index: The starting page index
740 * @nr_pages: The maximum number of pages
741 * @pages: Where the resulting pages are placed
743 * find_get_pages_contig() works exactly like find_get_pages(), except
744 * that the returned number of pages are guaranteed to be contiguous.
746 * find_get_pages_contig() returns the number of pages which were found.
748 unsigned find_get_pages_contig(struct address_space
*mapping
, pgoff_t index
,
749 unsigned int nr_pages
, struct page
**pages
)
754 read_lock_irq(&mapping
->tree_lock
);
755 ret
= radix_tree_gang_lookup(&mapping
->page_tree
,
756 (void **)pages
, index
, nr_pages
);
757 for (i
= 0; i
< ret
; i
++) {
758 if (pages
[i
]->mapping
== NULL
|| pages
[i
]->index
!= index
)
761 page_cache_get(pages
[i
]);
764 read_unlock_irq(&mapping
->tree_lock
);
769 * find_get_pages_tag - find and return pages that match @tag
770 * @mapping: the address_space to search
771 * @index: the starting page index
772 * @tag: the tag index
773 * @nr_pages: the maximum number of pages
774 * @pages: where the resulting pages are placed
776 * Like find_get_pages, except we only return pages which are tagged with
777 * @tag. We update @index to index the next page for the traversal.
779 unsigned find_get_pages_tag(struct address_space
*mapping
, pgoff_t
*index
,
780 int tag
, unsigned int nr_pages
, struct page
**pages
)
785 read_lock_irq(&mapping
->tree_lock
);
786 ret
= radix_tree_gang_lookup_tag(&mapping
->page_tree
,
787 (void **)pages
, *index
, nr_pages
, tag
);
788 for (i
= 0; i
< ret
; i
++)
789 page_cache_get(pages
[i
]);
791 *index
= pages
[ret
- 1]->index
+ 1;
792 read_unlock_irq(&mapping
->tree_lock
);
797 * grab_cache_page_nowait - returns locked page at given index in given cache
798 * @mapping: target address_space
799 * @index: the page index
801 * Same as grab_cache_page, but do not wait if the page is unavailable.
802 * This is intended for speculative data generators, where the data can
803 * be regenerated if the page couldn't be grabbed. This routine should
804 * be safe to call while holding the lock for another page.
806 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
807 * and deadlock against the caller's locked page.
810 grab_cache_page_nowait(struct address_space
*mapping
, unsigned long index
)
812 struct page
*page
= find_get_page(mapping
, index
);
816 if (!TestSetPageLocked(page
))
818 page_cache_release(page
);
821 gfp_mask
= mapping_gfp_mask(mapping
) & ~__GFP_FS
;
822 page
= alloc_pages(gfp_mask
, 0);
823 if (page
&& add_to_page_cache_lru(page
, mapping
, index
, gfp_mask
)) {
824 page_cache_release(page
);
829 EXPORT_SYMBOL(grab_cache_page_nowait
);
832 * do_generic_mapping_read - generic file read routine
833 * @mapping: address_space to be read
834 * @_ra: file's readahead state
835 * @filp: the file to read
836 * @ppos: current file position
837 * @desc: read_descriptor
838 * @actor: read method
840 * This is a generic file read routine, and uses the
841 * mapping->a_ops->readpage() function for the actual low-level stuff.
843 * This is really ugly. But the goto's actually try to clarify some
844 * of the logic when it comes to error handling etc.
846 * Note the struct file* is only passed for the use of readpage.
849 void do_generic_mapping_read(struct address_space
*mapping
,
850 struct file_ra_state
*_ra
,
853 read_descriptor_t
*desc
,
856 struct inode
*inode
= mapping
->host
;
858 unsigned long end_index
;
859 unsigned long offset
;
860 unsigned long last_index
;
861 unsigned long next_index
;
862 unsigned long prev_index
;
864 struct page
*cached_page
;
866 struct file_ra_state ra
= *_ra
;
869 index
= *ppos
>> PAGE_CACHE_SHIFT
;
871 prev_index
= ra
.prev_page
;
872 last_index
= (*ppos
+ desc
->count
+ PAGE_CACHE_SIZE
-1) >> PAGE_CACHE_SHIFT
;
873 offset
= *ppos
& ~PAGE_CACHE_MASK
;
875 isize
= i_size_read(inode
);
879 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
882 unsigned long nr
, ret
;
884 /* nr is the maximum number of bytes to copy from this page */
885 nr
= PAGE_CACHE_SIZE
;
886 if (index
>= end_index
) {
887 if (index
> end_index
)
889 nr
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
897 if (index
== next_index
)
898 next_index
= page_cache_readahead(mapping
, &ra
, filp
,
899 index
, last_index
- index
);
902 page
= find_get_page(mapping
, index
);
903 if (unlikely(page
== NULL
)) {
904 handle_ra_miss(mapping
, &ra
, index
);
907 if (!PageUptodate(page
))
908 goto page_not_up_to_date
;
911 /* If users can be writing to this page using arbitrary
912 * virtual addresses, take care about potential aliasing
913 * before reading the page on the kernel side.
915 if (mapping_writably_mapped(mapping
))
916 flush_dcache_page(page
);
919 * When (part of) the same page is read multiple times
920 * in succession, only mark it as accessed the first time.
922 if (prev_index
!= index
)
923 mark_page_accessed(page
);
927 * Ok, we have the page, and it's up-to-date, so
928 * now we can copy it to user space...
930 * The actor routine returns how many bytes were actually used..
931 * NOTE! This may not be the same as how much of a user buffer
932 * we filled up (we may be padding etc), so we can only update
933 * "pos" here (the actor routine has to update the user buffer
934 * pointers and the remaining count).
936 ret
= actor(desc
, page
, offset
, nr
);
938 index
+= offset
>> PAGE_CACHE_SHIFT
;
939 offset
&= ~PAGE_CACHE_MASK
;
941 page_cache_release(page
);
942 if (ret
== nr
&& desc
->count
)
947 /* Get exclusive access to the page ... */
950 /* Did it get unhashed before we got the lock? */
951 if (!page
->mapping
) {
953 page_cache_release(page
);
957 /* Did somebody else fill it already? */
958 if (PageUptodate(page
)) {
964 /* Start the actual read. The read will unlock the page. */
965 error
= mapping
->a_ops
->readpage(filp
, page
);
967 if (unlikely(error
)) {
968 if (error
== AOP_TRUNCATED_PAGE
) {
969 page_cache_release(page
);
975 if (!PageUptodate(page
)) {
977 if (!PageUptodate(page
)) {
978 if (page
->mapping
== NULL
) {
980 * invalidate_inode_pages got it
983 page_cache_release(page
);
994 * i_size must be checked after we have done ->readpage.
996 * Checking i_size after the readpage allows us to calculate
997 * the correct value for "nr", which means the zero-filled
998 * part of the page is not copied back to userspace (unless
999 * another truncate extends the file - this is desired though).
1001 isize
= i_size_read(inode
);
1002 end_index
= (isize
- 1) >> PAGE_CACHE_SHIFT
;
1003 if (unlikely(!isize
|| index
> end_index
)) {
1004 page_cache_release(page
);
1008 /* nr is the maximum number of bytes to copy from this page */
1009 nr
= PAGE_CACHE_SIZE
;
1010 if (index
== end_index
) {
1011 nr
= ((isize
- 1) & ~PAGE_CACHE_MASK
) + 1;
1013 page_cache_release(page
);
1021 /* UHHUH! A synchronous read error occurred. Report it */
1022 desc
->error
= error
;
1023 page_cache_release(page
);
1028 * Ok, it wasn't cached, so we need to create a new
1032 cached_page
= page_cache_alloc_cold(mapping
);
1034 desc
->error
= -ENOMEM
;
1038 error
= add_to_page_cache_lru(cached_page
, mapping
,
1041 if (error
== -EEXIST
)
1043 desc
->error
= error
;
1054 *ppos
= ((loff_t
) index
<< PAGE_CACHE_SHIFT
) + offset
;
1056 page_cache_release(cached_page
);
1058 file_accessed(filp
);
1060 EXPORT_SYMBOL(do_generic_mapping_read
);
1062 int file_read_actor(read_descriptor_t
*desc
, struct page
*page
,
1063 unsigned long offset
, unsigned long size
)
1066 unsigned long left
, count
= desc
->count
;
1072 * Faults on the destination of a read are common, so do it before
1075 if (!fault_in_pages_writeable(desc
->arg
.buf
, size
)) {
1076 kaddr
= kmap_atomic(page
, KM_USER0
);
1077 left
= __copy_to_user_inatomic(desc
->arg
.buf
,
1078 kaddr
+ offset
, size
);
1079 kunmap_atomic(kaddr
, KM_USER0
);
1084 /* Do it the slow way */
1086 left
= __copy_to_user(desc
->arg
.buf
, kaddr
+ offset
, size
);
1091 desc
->error
= -EFAULT
;
1094 desc
->count
= count
- size
;
1095 desc
->written
+= size
;
1096 desc
->arg
.buf
+= size
;
1101 * __generic_file_aio_read - generic filesystem read routine
1102 * @iocb: kernel I/O control block
1103 * @iov: io vector request
1104 * @nr_segs: number of segments in the iovec
1105 * @ppos: current file position
1107 * This is the "read()" routine for all filesystems
1108 * that can use the page cache directly.
1111 __generic_file_aio_read(struct kiocb
*iocb
, const struct iovec
*iov
,
1112 unsigned long nr_segs
, loff_t
*ppos
)
1114 struct file
*filp
= iocb
->ki_filp
;
1120 for (seg
= 0; seg
< nr_segs
; seg
++) {
1121 const struct iovec
*iv
= &iov
[seg
];
1124 * If any segment has a negative length, or the cumulative
1125 * length ever wraps negative then return -EINVAL.
1127 count
+= iv
->iov_len
;
1128 if (unlikely((ssize_t
)(count
|iv
->iov_len
) < 0))
1130 if (access_ok(VERIFY_WRITE
, iv
->iov_base
, iv
->iov_len
))
1135 count
-= iv
->iov_len
; /* This segment is no good */
1139 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1140 if (filp
->f_flags
& O_DIRECT
) {
1141 loff_t pos
= *ppos
, size
;
1142 struct address_space
*mapping
;
1143 struct inode
*inode
;
1145 mapping
= filp
->f_mapping
;
1146 inode
= mapping
->host
;
1149 goto out
; /* skip atime */
1150 size
= i_size_read(inode
);
1152 retval
= generic_file_direct_IO(READ
, iocb
,
1154 if (retval
> 0 && !is_sync_kiocb(iocb
))
1155 retval
= -EIOCBQUEUED
;
1157 *ppos
= pos
+ retval
;
1159 file_accessed(filp
);
1165 for (seg
= 0; seg
< nr_segs
; seg
++) {
1166 read_descriptor_t desc
;
1169 desc
.arg
.buf
= iov
[seg
].iov_base
;
1170 desc
.count
= iov
[seg
].iov_len
;
1171 if (desc
.count
== 0)
1174 do_generic_file_read(filp
,ppos
,&desc
,file_read_actor
);
1175 retval
+= desc
.written
;
1177 retval
= retval
?: desc
.error
;
1185 EXPORT_SYMBOL(__generic_file_aio_read
);
1188 generic_file_aio_read(struct kiocb
*iocb
, char __user
*buf
, size_t count
, loff_t pos
)
1190 struct iovec local_iov
= { .iov_base
= buf
, .iov_len
= count
};
1192 BUG_ON(iocb
->ki_pos
!= pos
);
1193 return __generic_file_aio_read(iocb
, &local_iov
, 1, &iocb
->ki_pos
);
1195 EXPORT_SYMBOL(generic_file_aio_read
);
1198 generic_file_read(struct file
*filp
, char __user
*buf
, size_t count
, loff_t
*ppos
)
1200 struct iovec local_iov
= { .iov_base
= buf
, .iov_len
= count
};
1204 init_sync_kiocb(&kiocb
, filp
);
1205 ret
= __generic_file_aio_read(&kiocb
, &local_iov
, 1, ppos
);
1206 if (-EIOCBQUEUED
== ret
)
1207 ret
= wait_on_sync_kiocb(&kiocb
);
1210 EXPORT_SYMBOL(generic_file_read
);
1212 int file_send_actor(read_descriptor_t
* desc
, struct page
*page
, unsigned long offset
, unsigned long size
)
1215 unsigned long count
= desc
->count
;
1216 struct file
*file
= desc
->arg
.data
;
1221 written
= file
->f_op
->sendpage(file
, page
, offset
,
1222 size
, &file
->f_pos
, size
<count
);
1224 desc
->error
= written
;
1227 desc
->count
= count
- written
;
1228 desc
->written
+= written
;
1232 ssize_t
generic_file_sendfile(struct file
*in_file
, loff_t
*ppos
,
1233 size_t count
, read_actor_t actor
, void *target
)
1235 read_descriptor_t desc
;
1242 desc
.arg
.data
= target
;
1245 do_generic_file_read(in_file
, ppos
, &desc
, actor
);
1247 return desc
.written
;
1250 EXPORT_SYMBOL(generic_file_sendfile
);
1253 do_readahead(struct address_space
*mapping
, struct file
*filp
,
1254 unsigned long index
, unsigned long nr
)
1256 if (!mapping
|| !mapping
->a_ops
|| !mapping
->a_ops
->readpage
)
1259 force_page_cache_readahead(mapping
, filp
, index
,
1260 max_sane_readahead(nr
));
1264 asmlinkage ssize_t
sys_readahead(int fd
, loff_t offset
, size_t count
)
1272 if (file
->f_mode
& FMODE_READ
) {
1273 struct address_space
*mapping
= file
->f_mapping
;
1274 unsigned long start
= offset
>> PAGE_CACHE_SHIFT
;
1275 unsigned long end
= (offset
+ count
- 1) >> PAGE_CACHE_SHIFT
;
1276 unsigned long len
= end
- start
+ 1;
1277 ret
= do_readahead(mapping
, file
, start
, len
);
1285 static int FASTCALL(page_cache_read(struct file
* file
, unsigned long offset
));
1287 * page_cache_read - adds requested page to the page cache if not already there
1288 * @file: file to read
1289 * @offset: page index
1291 * This adds the requested page to the page cache if it isn't already there,
1292 * and schedules an I/O to read in its contents from disk.
1294 static int fastcall
page_cache_read(struct file
* file
, unsigned long offset
)
1296 struct address_space
*mapping
= file
->f_mapping
;
1301 page
= page_cache_alloc_cold(mapping
);
1305 ret
= add_to_page_cache_lru(page
, mapping
, offset
, GFP_KERNEL
);
1307 ret
= mapping
->a_ops
->readpage(file
, page
);
1308 else if (ret
== -EEXIST
)
1309 ret
= 0; /* losing race to add is OK */
1311 page_cache_release(page
);
1313 } while (ret
== AOP_TRUNCATED_PAGE
);
1318 #define MMAP_LOTSAMISS (100)
1321 * filemap_nopage - read in file data for page fault handling
1322 * @area: the applicable vm_area
1323 * @address: target address to read in
1324 * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1326 * filemap_nopage() is invoked via the vma operations vector for a
1327 * mapped memory region to read in file data during a page fault.
1329 * The goto's are kind of ugly, but this streamlines the normal case of having
1330 * it in the page cache, and handles the special cases reasonably without
1331 * having a lot of duplicated code.
1333 struct page
*filemap_nopage(struct vm_area_struct
*area
,
1334 unsigned long address
, int *type
)
1337 struct file
*file
= area
->vm_file
;
1338 struct address_space
*mapping
= file
->f_mapping
;
1339 struct file_ra_state
*ra
= &file
->f_ra
;
1340 struct inode
*inode
= mapping
->host
;
1342 unsigned long size
, pgoff
;
1343 int did_readaround
= 0, majmin
= VM_FAULT_MINOR
;
1345 pgoff
= ((address
-area
->vm_start
) >> PAGE_CACHE_SHIFT
) + area
->vm_pgoff
;
1348 size
= (i_size_read(inode
) + PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1350 goto outside_data_content
;
1352 /* If we don't want any read-ahead, don't bother */
1353 if (VM_RandomReadHint(area
))
1354 goto no_cached_page
;
1357 * The readahead code wants to be told about each and every page
1358 * so it can build and shrink its windows appropriately
1360 * For sequential accesses, we use the generic readahead logic.
1362 if (VM_SequentialReadHint(area
))
1363 page_cache_readahead(mapping
, ra
, file
, pgoff
, 1);
1366 * Do we have something in the page cache already?
1369 page
= find_get_page(mapping
, pgoff
);
1371 unsigned long ra_pages
;
1373 if (VM_SequentialReadHint(area
)) {
1374 handle_ra_miss(mapping
, ra
, pgoff
);
1375 goto no_cached_page
;
1380 * Do we miss much more than hit in this file? If so,
1381 * stop bothering with read-ahead. It will only hurt.
1383 if (ra
->mmap_miss
> ra
->mmap_hit
+ MMAP_LOTSAMISS
)
1384 goto no_cached_page
;
1387 * To keep the pgmajfault counter straight, we need to
1388 * check did_readaround, as this is an inner loop.
1390 if (!did_readaround
) {
1391 majmin
= VM_FAULT_MAJOR
;
1392 inc_page_state(pgmajfault
);
1395 ra_pages
= max_sane_readahead(file
->f_ra
.ra_pages
);
1399 if (pgoff
> ra_pages
/ 2)
1400 start
= pgoff
- ra_pages
/ 2;
1401 do_page_cache_readahead(mapping
, file
, start
, ra_pages
);
1403 page
= find_get_page(mapping
, pgoff
);
1405 goto no_cached_page
;
1408 if (!did_readaround
)
1412 * Ok, found a page in the page cache, now we need to check
1413 * that it's up-to-date.
1415 if (!PageUptodate(page
))
1416 goto page_not_uptodate
;
1420 * Found the page and have a reference on it.
1422 mark_page_accessed(page
);
1427 outside_data_content
:
1429 * An external ptracer can access pages that normally aren't
1432 if (area
->vm_mm
== current
->mm
)
1434 /* Fall through to the non-read-ahead case */
1437 * We're only likely to ever get here if MADV_RANDOM is in
1440 error
= page_cache_read(file
, pgoff
);
1444 * The page we want has now been added to the page cache.
1445 * In the unlikely event that someone removed it in the
1446 * meantime, we'll just come back here and read it again.
1452 * An error return from page_cache_read can result if the
1453 * system is low on memory, or a problem occurs while trying
1456 if (error
== -ENOMEM
)
1461 if (!did_readaround
) {
1462 majmin
= VM_FAULT_MAJOR
;
1463 inc_page_state(pgmajfault
);
1467 /* Did it get unhashed while we waited for it? */
1468 if (!page
->mapping
) {
1470 page_cache_release(page
);
1474 /* Did somebody else get it up-to-date? */
1475 if (PageUptodate(page
)) {
1480 error
= mapping
->a_ops
->readpage(file
, page
);
1482 wait_on_page_locked(page
);
1483 if (PageUptodate(page
))
1485 } else if (error
== AOP_TRUNCATED_PAGE
) {
1486 page_cache_release(page
);
1491 * Umm, take care of errors if the page isn't up-to-date.
1492 * Try to re-read it _once_. We do this synchronously,
1493 * because there really aren't any performance issues here
1494 * and we need to check for errors.
1498 /* Somebody truncated the page on us? */
1499 if (!page
->mapping
) {
1501 page_cache_release(page
);
1505 /* Somebody else successfully read it in? */
1506 if (PageUptodate(page
)) {
1510 ClearPageError(page
);
1511 error
= mapping
->a_ops
->readpage(file
, page
);
1513 wait_on_page_locked(page
);
1514 if (PageUptodate(page
))
1516 } else if (error
== AOP_TRUNCATED_PAGE
) {
1517 page_cache_release(page
);
1522 * Things didn't work out. Return zero to tell the
1523 * mm layer so, possibly freeing the page cache page first.
1525 page_cache_release(page
);
1528 EXPORT_SYMBOL(filemap_nopage
);
1530 static struct page
* filemap_getpage(struct file
*file
, unsigned long pgoff
,
1533 struct address_space
*mapping
= file
->f_mapping
;
1538 * Do we have something in the page cache already?
1541 page
= find_get_page(mapping
, pgoff
);
1545 goto no_cached_page
;
1549 * Ok, found a page in the page cache, now we need to check
1550 * that it's up-to-date.
1552 if (!PageUptodate(page
)) {
1554 page_cache_release(page
);
1557 goto page_not_uptodate
;
1562 * Found the page and have a reference on it.
1564 mark_page_accessed(page
);
1568 error
= page_cache_read(file
, pgoff
);
1571 * The page we want has now been added to the page cache.
1572 * In the unlikely event that someone removed it in the
1573 * meantime, we'll just come back here and read it again.
1579 * An error return from page_cache_read can result if the
1580 * system is low on memory, or a problem occurs while trying
1588 /* Did it get unhashed while we waited for it? */
1589 if (!page
->mapping
) {
1594 /* Did somebody else get it up-to-date? */
1595 if (PageUptodate(page
)) {
1600 error
= mapping
->a_ops
->readpage(file
, page
);
1602 wait_on_page_locked(page
);
1603 if (PageUptodate(page
))
1605 } else if (error
== AOP_TRUNCATED_PAGE
) {
1606 page_cache_release(page
);
1611 * Umm, take care of errors if the page isn't up-to-date.
1612 * Try to re-read it _once_. We do this synchronously,
1613 * because there really aren't any performance issues here
1614 * and we need to check for errors.
1618 /* Somebody truncated the page on us? */
1619 if (!page
->mapping
) {
1623 /* Somebody else successfully read it in? */
1624 if (PageUptodate(page
)) {
1629 ClearPageError(page
);
1630 error
= mapping
->a_ops
->readpage(file
, page
);
1632 wait_on_page_locked(page
);
1633 if (PageUptodate(page
))
1635 } else if (error
== AOP_TRUNCATED_PAGE
) {
1636 page_cache_release(page
);
1641 * Things didn't work out. Return zero to tell the
1642 * mm layer so, possibly freeing the page cache page first.
1645 page_cache_release(page
);
1650 int filemap_populate(struct vm_area_struct
*vma
, unsigned long addr
,
1651 unsigned long len
, pgprot_t prot
, unsigned long pgoff
,
1654 struct file
*file
= vma
->vm_file
;
1655 struct address_space
*mapping
= file
->f_mapping
;
1656 struct inode
*inode
= mapping
->host
;
1658 struct mm_struct
*mm
= vma
->vm_mm
;
1663 force_page_cache_readahead(mapping
, vma
->vm_file
,
1664 pgoff
, len
>> PAGE_CACHE_SHIFT
);
1667 size
= (i_size_read(inode
) + PAGE_CACHE_SIZE
- 1) >> PAGE_CACHE_SHIFT
;
1668 if (pgoff
+ (len
>> PAGE_CACHE_SHIFT
) > size
)
1671 page
= filemap_getpage(file
, pgoff
, nonblock
);
1673 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1674 * done in shmem_populate calling shmem_getpage */
1675 if (!page
&& !nonblock
)
1679 err
= install_page(mm
, vma
, addr
, page
, prot
);
1681 page_cache_release(page
);
1684 } else if (vma
->vm_flags
& VM_NONLINEAR
) {
1685 /* No page was found just because we can't read it in now (being
1686 * here implies nonblock != 0), but the page may exist, so set
1687 * the PTE to fault it in later. */
1688 err
= install_file_pte(mm
, vma
, addr
, pgoff
, prot
);
1701 EXPORT_SYMBOL(filemap_populate
);
1703 struct vm_operations_struct generic_file_vm_ops
= {
1704 .nopage
= filemap_nopage
,
1705 .populate
= filemap_populate
,
1708 /* This is used for a general mmap of a disk file */
1710 int generic_file_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1712 struct address_space
*mapping
= file
->f_mapping
;
1714 if (!mapping
->a_ops
->readpage
)
1716 file_accessed(file
);
1717 vma
->vm_ops
= &generic_file_vm_ops
;
1722 * This is for filesystems which do not implement ->writepage.
1724 int generic_file_readonly_mmap(struct file
*file
, struct vm_area_struct
*vma
)
1726 if ((vma
->vm_flags
& VM_SHARED
) && (vma
->vm_flags
& VM_MAYWRITE
))
1728 return generic_file_mmap(file
, vma
);
1731 int generic_file_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1735 int generic_file_readonly_mmap(struct file
* file
, struct vm_area_struct
* vma
)
1739 #endif /* CONFIG_MMU */
1741 EXPORT_SYMBOL(generic_file_mmap
);
1742 EXPORT_SYMBOL(generic_file_readonly_mmap
);
1744 static inline struct page
*__read_cache_page(struct address_space
*mapping
,
1745 unsigned long index
,
1746 int (*filler
)(void *,struct page
*),
1749 struct page
*page
, *cached_page
= NULL
;
1752 page
= find_get_page(mapping
, index
);
1755 cached_page
= page_cache_alloc_cold(mapping
);
1757 return ERR_PTR(-ENOMEM
);
1759 err
= add_to_page_cache_lru(cached_page
, mapping
,
1764 /* Presumably ENOMEM for radix tree node */
1765 page_cache_release(cached_page
);
1766 return ERR_PTR(err
);
1770 err
= filler(data
, page
);
1772 page_cache_release(page
);
1773 page
= ERR_PTR(err
);
1777 page_cache_release(cached_page
);
1782 * read_cache_page - read into page cache, fill it if needed
1783 * @mapping: the page's address_space
1784 * @index: the page index
1785 * @filler: function to perform the read
1786 * @data: destination for read data
1788 * Read into the page cache. If a page already exists,
1789 * and PageUptodate() is not set, try to fill the page.
1791 struct page
*read_cache_page(struct address_space
*mapping
,
1792 unsigned long index
,
1793 int (*filler
)(void *,struct page
*),
1800 page
= __read_cache_page(mapping
, index
, filler
, data
);
1803 mark_page_accessed(page
);
1804 if (PageUptodate(page
))
1808 if (!page
->mapping
) {
1810 page_cache_release(page
);
1813 if (PageUptodate(page
)) {
1817 err
= filler(data
, page
);
1819 page_cache_release(page
);
1820 page
= ERR_PTR(err
);
1825 EXPORT_SYMBOL(read_cache_page
);
1828 * If the page was newly created, increment its refcount and add it to the
1829 * caller's lru-buffering pagevec. This function is specifically for
1830 * generic_file_write().
1832 static inline struct page
*
1833 __grab_cache_page(struct address_space
*mapping
, unsigned long index
,
1834 struct page
**cached_page
, struct pagevec
*lru_pvec
)
1839 page
= find_lock_page(mapping
, index
);
1841 if (!*cached_page
) {
1842 *cached_page
= page_cache_alloc(mapping
);
1846 err
= add_to_page_cache(*cached_page
, mapping
,
1851 page
= *cached_page
;
1852 page_cache_get(page
);
1853 if (!pagevec_add(lru_pvec
, page
))
1854 __pagevec_lru_add(lru_pvec
);
1855 *cached_page
= NULL
;
1862 * The logic we want is
1864 * if suid or (sgid and xgrp)
1867 int remove_suid(struct dentry
*dentry
)
1869 mode_t mode
= dentry
->d_inode
->i_mode
;
1873 /* suid always must be killed */
1874 if (unlikely(mode
& S_ISUID
))
1875 kill
= ATTR_KILL_SUID
;
1878 * sgid without any exec bits is just a mandatory locking mark; leave
1879 * it alone. If some exec bits are set, it's a real sgid; kill it.
1881 if (unlikely((mode
& S_ISGID
) && (mode
& S_IXGRP
)))
1882 kill
|= ATTR_KILL_SGID
;
1884 if (unlikely(kill
&& !capable(CAP_FSETID
))) {
1885 struct iattr newattrs
;
1887 newattrs
.ia_valid
= ATTR_FORCE
| kill
;
1888 result
= notify_change(dentry
, &newattrs
);
1892 EXPORT_SYMBOL(remove_suid
);
1895 __filemap_copy_from_user_iovec_inatomic(char *vaddr
,
1896 const struct iovec
*iov
, size_t base
, size_t bytes
)
1898 size_t copied
= 0, left
= 0;
1901 char __user
*buf
= iov
->iov_base
+ base
;
1902 int copy
= min(bytes
, iov
->iov_len
- base
);
1905 left
= __copy_from_user_inatomic_nocache(vaddr
, buf
, copy
);
1914 return copied
- left
;
1918 * Performs necessary checks before doing a write
1920 * Can adjust writing position or amount of bytes to write.
1921 * Returns appropriate error code that caller should return or
1922 * zero in case that write should be allowed.
1924 inline int generic_write_checks(struct file
*file
, loff_t
*pos
, size_t *count
, int isblk
)
1926 struct inode
*inode
= file
->f_mapping
->host
;
1927 unsigned long limit
= current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
;
1929 if (unlikely(*pos
< 0))
1933 /* FIXME: this is for backwards compatibility with 2.4 */
1934 if (file
->f_flags
& O_APPEND
)
1935 *pos
= i_size_read(inode
);
1937 if (limit
!= RLIM_INFINITY
) {
1938 if (*pos
>= limit
) {
1939 send_sig(SIGXFSZ
, current
, 0);
1942 if (*count
> limit
- (typeof(limit
))*pos
) {
1943 *count
= limit
- (typeof(limit
))*pos
;
1951 if (unlikely(*pos
+ *count
> MAX_NON_LFS
&&
1952 !(file
->f_flags
& O_LARGEFILE
))) {
1953 if (*pos
>= MAX_NON_LFS
) {
1954 send_sig(SIGXFSZ
, current
, 0);
1957 if (*count
> MAX_NON_LFS
- (unsigned long)*pos
) {
1958 *count
= MAX_NON_LFS
- (unsigned long)*pos
;
1963 * Are we about to exceed the fs block limit ?
1965 * If we have written data it becomes a short write. If we have
1966 * exceeded without writing data we send a signal and return EFBIG.
1967 * Linus frestrict idea will clean these up nicely..
1969 if (likely(!isblk
)) {
1970 if (unlikely(*pos
>= inode
->i_sb
->s_maxbytes
)) {
1971 if (*count
|| *pos
> inode
->i_sb
->s_maxbytes
) {
1972 send_sig(SIGXFSZ
, current
, 0);
1975 /* zero-length writes at ->s_maxbytes are OK */
1978 if (unlikely(*pos
+ *count
> inode
->i_sb
->s_maxbytes
))
1979 *count
= inode
->i_sb
->s_maxbytes
- *pos
;
1982 if (bdev_read_only(I_BDEV(inode
)))
1984 isize
= i_size_read(inode
);
1985 if (*pos
>= isize
) {
1986 if (*count
|| *pos
> isize
)
1990 if (*pos
+ *count
> isize
)
1991 *count
= isize
- *pos
;
1995 EXPORT_SYMBOL(generic_write_checks
);
1998 generic_file_direct_write(struct kiocb
*iocb
, const struct iovec
*iov
,
1999 unsigned long *nr_segs
, loff_t pos
, loff_t
*ppos
,
2000 size_t count
, size_t ocount
)
2002 struct file
*file
= iocb
->ki_filp
;
2003 struct address_space
*mapping
= file
->f_mapping
;
2004 struct inode
*inode
= mapping
->host
;
2007 if (count
!= ocount
)
2008 *nr_segs
= iov_shorten((struct iovec
*)iov
, *nr_segs
, count
);
2010 written
= generic_file_direct_IO(WRITE
, iocb
, iov
, pos
, *nr_segs
);
2012 loff_t end
= pos
+ written
;
2013 if (end
> i_size_read(inode
) && !S_ISBLK(inode
->i_mode
)) {
2014 i_size_write(inode
, end
);
2015 mark_inode_dirty(inode
);
2021 * Sync the fs metadata but not the minor inode changes and
2022 * of course not the data as we did direct DMA for the IO.
2023 * i_mutex is held, which protects generic_osync_inode() from
2026 if (written
>= 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2027 int err
= generic_osync_inode(inode
, mapping
, OSYNC_METADATA
);
2031 if (written
== count
&& !is_sync_kiocb(iocb
))
2032 written
= -EIOCBQUEUED
;
2035 EXPORT_SYMBOL(generic_file_direct_write
);
2038 generic_file_buffered_write(struct kiocb
*iocb
, const struct iovec
*iov
,
2039 unsigned long nr_segs
, loff_t pos
, loff_t
*ppos
,
2040 size_t count
, ssize_t written
)
2042 struct file
*file
= iocb
->ki_filp
;
2043 struct address_space
* mapping
= file
->f_mapping
;
2044 struct address_space_operations
*a_ops
= mapping
->a_ops
;
2045 struct inode
*inode
= mapping
->host
;
2048 struct page
*cached_page
= NULL
;
2050 struct pagevec lru_pvec
;
2051 const struct iovec
*cur_iov
= iov
; /* current iovec */
2052 size_t iov_base
= 0; /* offset in the current iovec */
2055 pagevec_init(&lru_pvec
, 0);
2058 * handle partial DIO write. Adjust cur_iov if needed.
2060 if (likely(nr_segs
== 1))
2061 buf
= iov
->iov_base
+ written
;
2063 filemap_set_next_iovec(&cur_iov
, &iov_base
, written
);
2064 buf
= cur_iov
->iov_base
+ iov_base
;
2068 unsigned long index
;
2069 unsigned long offset
;
2070 unsigned long maxlen
;
2073 offset
= (pos
& (PAGE_CACHE_SIZE
-1)); /* Within page */
2074 index
= pos
>> PAGE_CACHE_SHIFT
;
2075 bytes
= PAGE_CACHE_SIZE
- offset
;
2080 * Bring in the user page that we will copy from _first_.
2081 * Otherwise there's a nasty deadlock on copying from the
2082 * same page as we're writing to, without it being marked
2085 maxlen
= cur_iov
->iov_len
- iov_base
;
2088 fault_in_pages_readable(buf
, maxlen
);
2090 page
= __grab_cache_page(mapping
,index
,&cached_page
,&lru_pvec
);
2096 status
= a_ops
->prepare_write(file
, page
, offset
, offset
+bytes
);
2097 if (unlikely(status
)) {
2098 loff_t isize
= i_size_read(inode
);
2100 if (status
!= AOP_TRUNCATED_PAGE
)
2102 page_cache_release(page
);
2103 if (status
== AOP_TRUNCATED_PAGE
)
2106 * prepare_write() may have instantiated a few blocks
2107 * outside i_size. Trim these off again.
2109 if (pos
+ bytes
> isize
)
2110 vmtruncate(inode
, isize
);
2113 if (likely(nr_segs
== 1))
2114 copied
= filemap_copy_from_user(page
, offset
,
2117 copied
= filemap_copy_from_user_iovec(page
, offset
,
2118 cur_iov
, iov_base
, bytes
);
2119 flush_dcache_page(page
);
2120 status
= a_ops
->commit_write(file
, page
, offset
, offset
+bytes
);
2121 if (status
== AOP_TRUNCATED_PAGE
) {
2122 page_cache_release(page
);
2125 if (likely(copied
> 0)) {
2134 if (unlikely(nr_segs
> 1)) {
2135 filemap_set_next_iovec(&cur_iov
,
2138 buf
= cur_iov
->iov_base
+
2145 if (unlikely(copied
!= bytes
))
2149 mark_page_accessed(page
);
2150 page_cache_release(page
);
2153 balance_dirty_pages_ratelimited(mapping
);
2159 page_cache_release(cached_page
);
2162 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2164 if (likely(status
>= 0)) {
2165 if (unlikely((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2166 if (!a_ops
->writepage
|| !is_sync_kiocb(iocb
))
2167 status
= generic_osync_inode(inode
, mapping
,
2168 OSYNC_METADATA
|OSYNC_DATA
);
2173 * If we get here for O_DIRECT writes then we must have fallen through
2174 * to buffered writes (block instantiation inside i_size). So we sync
2175 * the file data here, to try to honour O_DIRECT expectations.
2177 if (unlikely(file
->f_flags
& O_DIRECT
) && written
)
2178 status
= filemap_write_and_wait(mapping
);
2180 pagevec_lru_add(&lru_pvec
);
2181 return written
? written
: status
;
2183 EXPORT_SYMBOL(generic_file_buffered_write
);
2186 __generic_file_aio_write_nolock(struct kiocb
*iocb
, const struct iovec
*iov
,
2187 unsigned long nr_segs
, loff_t
*ppos
)
2189 struct file
*file
= iocb
->ki_filp
;
2190 struct address_space
* mapping
= file
->f_mapping
;
2191 size_t ocount
; /* original count */
2192 size_t count
; /* after file limit checks */
2193 struct inode
*inode
= mapping
->host
;
2200 for (seg
= 0; seg
< nr_segs
; seg
++) {
2201 const struct iovec
*iv
= &iov
[seg
];
2204 * If any segment has a negative length, or the cumulative
2205 * length ever wraps negative then return -EINVAL.
2207 ocount
+= iv
->iov_len
;
2208 if (unlikely((ssize_t
)(ocount
|iv
->iov_len
) < 0))
2210 if (access_ok(VERIFY_READ
, iv
->iov_base
, iv
->iov_len
))
2215 ocount
-= iv
->iov_len
; /* This segment is no good */
2222 vfs_check_frozen(inode
->i_sb
, SB_FREEZE_WRITE
);
2224 /* We can write back this queue in page reclaim */
2225 current
->backing_dev_info
= mapping
->backing_dev_info
;
2228 err
= generic_write_checks(file
, &pos
, &count
, S_ISBLK(inode
->i_mode
));
2235 err
= remove_suid(file
->f_dentry
);
2239 file_update_time(file
);
2241 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2242 if (unlikely(file
->f_flags
& O_DIRECT
)) {
2243 written
= generic_file_direct_write(iocb
, iov
,
2244 &nr_segs
, pos
, ppos
, count
, ocount
);
2245 if (written
< 0 || written
== count
)
2248 * direct-io write to a hole: fall through to buffered I/O
2249 * for completing the rest of the request.
2255 written
= generic_file_buffered_write(iocb
, iov
, nr_segs
,
2256 pos
, ppos
, count
, written
);
2258 current
->backing_dev_info
= NULL
;
2259 return written
? written
: err
;
2261 EXPORT_SYMBOL(generic_file_aio_write_nolock
);
2264 generic_file_aio_write_nolock(struct kiocb
*iocb
, const struct iovec
*iov
,
2265 unsigned long nr_segs
, loff_t
*ppos
)
2267 struct file
*file
= iocb
->ki_filp
;
2268 struct address_space
*mapping
= file
->f_mapping
;
2269 struct inode
*inode
= mapping
->host
;
2273 ret
= __generic_file_aio_write_nolock(iocb
, iov
, nr_segs
, ppos
);
2275 if (ret
> 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2278 err
= sync_page_range_nolock(inode
, mapping
, pos
, ret
);
2286 __generic_file_write_nolock(struct file
*file
, const struct iovec
*iov
,
2287 unsigned long nr_segs
, loff_t
*ppos
)
2292 init_sync_kiocb(&kiocb
, file
);
2293 ret
= __generic_file_aio_write_nolock(&kiocb
, iov
, nr_segs
, ppos
);
2294 if (ret
== -EIOCBQUEUED
)
2295 ret
= wait_on_sync_kiocb(&kiocb
);
2300 generic_file_write_nolock(struct file
*file
, const struct iovec
*iov
,
2301 unsigned long nr_segs
, loff_t
*ppos
)
2306 init_sync_kiocb(&kiocb
, file
);
2307 ret
= generic_file_aio_write_nolock(&kiocb
, iov
, nr_segs
, ppos
);
2308 if (-EIOCBQUEUED
== ret
)
2309 ret
= wait_on_sync_kiocb(&kiocb
);
2312 EXPORT_SYMBOL(generic_file_write_nolock
);
2314 ssize_t
generic_file_aio_write(struct kiocb
*iocb
, const char __user
*buf
,
2315 size_t count
, loff_t pos
)
2317 struct file
*file
= iocb
->ki_filp
;
2318 struct address_space
*mapping
= file
->f_mapping
;
2319 struct inode
*inode
= mapping
->host
;
2321 struct iovec local_iov
= { .iov_base
= (void __user
*)buf
,
2324 BUG_ON(iocb
->ki_pos
!= pos
);
2326 mutex_lock(&inode
->i_mutex
);
2327 ret
= __generic_file_aio_write_nolock(iocb
, &local_iov
, 1,
2329 mutex_unlock(&inode
->i_mutex
);
2331 if (ret
> 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2334 err
= sync_page_range(inode
, mapping
, pos
, ret
);
2340 EXPORT_SYMBOL(generic_file_aio_write
);
2342 ssize_t
generic_file_write(struct file
*file
, const char __user
*buf
,
2343 size_t count
, loff_t
*ppos
)
2345 struct address_space
*mapping
= file
->f_mapping
;
2346 struct inode
*inode
= mapping
->host
;
2348 struct iovec local_iov
= { .iov_base
= (void __user
*)buf
,
2351 mutex_lock(&inode
->i_mutex
);
2352 ret
= __generic_file_write_nolock(file
, &local_iov
, 1, ppos
);
2353 mutex_unlock(&inode
->i_mutex
);
2355 if (ret
> 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2358 err
= sync_page_range(inode
, mapping
, *ppos
- ret
, ret
);
2364 EXPORT_SYMBOL(generic_file_write
);
2366 ssize_t
generic_file_readv(struct file
*filp
, const struct iovec
*iov
,
2367 unsigned long nr_segs
, loff_t
*ppos
)
2372 init_sync_kiocb(&kiocb
, filp
);
2373 ret
= __generic_file_aio_read(&kiocb
, iov
, nr_segs
, ppos
);
2374 if (-EIOCBQUEUED
== ret
)
2375 ret
= wait_on_sync_kiocb(&kiocb
);
2378 EXPORT_SYMBOL(generic_file_readv
);
2380 ssize_t
generic_file_writev(struct file
*file
, const struct iovec
*iov
,
2381 unsigned long nr_segs
, loff_t
*ppos
)
2383 struct address_space
*mapping
= file
->f_mapping
;
2384 struct inode
*inode
= mapping
->host
;
2387 mutex_lock(&inode
->i_mutex
);
2388 ret
= __generic_file_write_nolock(file
, iov
, nr_segs
, ppos
);
2389 mutex_unlock(&inode
->i_mutex
);
2391 if (ret
> 0 && ((file
->f_flags
& O_SYNC
) || IS_SYNC(inode
))) {
2394 err
= sync_page_range(inode
, mapping
, *ppos
- ret
, ret
);
2400 EXPORT_SYMBOL(generic_file_writev
);
2403 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
2404 * went wrong during pagecache shootdown.
2407 generic_file_direct_IO(int rw
, struct kiocb
*iocb
, const struct iovec
*iov
,
2408 loff_t offset
, unsigned long nr_segs
)
2410 struct file
*file
= iocb
->ki_filp
;
2411 struct address_space
*mapping
= file
->f_mapping
;
2413 size_t write_len
= 0;
2416 * If it's a write, unmap all mmappings of the file up-front. This
2417 * will cause any pte dirty bits to be propagated into the pageframes
2418 * for the subsequent filemap_write_and_wait().
2421 write_len
= iov_length(iov
, nr_segs
);
2422 if (mapping_mapped(mapping
))
2423 unmap_mapping_range(mapping
, offset
, write_len
, 0);
2426 retval
= filemap_write_and_wait(mapping
);
2428 retval
= mapping
->a_ops
->direct_IO(rw
, iocb
, iov
,
2430 if (rw
== WRITE
&& mapping
->nrpages
) {
2431 pgoff_t end
= (offset
+ write_len
- 1)
2432 >> PAGE_CACHE_SHIFT
;
2433 int err
= invalidate_inode_pages2_range(mapping
,
2434 offset
>> PAGE_CACHE_SHIFT
, end
);