ia64/linux-2.6.18-xen.hg

view mm/filemap.c @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents cad6f60f0506
children
line source
1 /*
2 * linux/mm/filemap.c
3 *
4 * Copyright (C) 1994-1999 Linus Torvalds
5 */
7 /*
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)
11 */
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/compiler.h>
15 #include <linux/fs.h>
16 #include <linux/uaccess.h>
17 #include <linux/aio.h>
18 #include <linux/capability.h>
19 #include <linux/kernel_stat.h>
20 #include <linux/mm.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/pagevec.h>
29 #include <linux/blkdev.h>
30 #include <linux/security.h>
31 #include <linux/syscalls.h>
32 #include <linux/cpuset.h>
33 #include <linux/precache.h>
34 #include "filemap.h"
35 #include "internal.h"
37 /*
38 * FIXME: remove all knowledge of the buffer layer from the core VM
39 */
40 #include <linux/buffer_head.h> /* for generic_osync_inode */
42 #include <asm/mman.h>
44 static ssize_t
45 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
46 loff_t offset, unsigned long nr_segs);
48 /*
49 * Shared mappings implemented 30.11.1994. It's not fully working yet,
50 * though.
51 *
52 * Shared mappings now work. 15.8.1995 Bruno.
53 *
54 * finished 'unifying' the page and buffer cache and SMP-threaded the
55 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
56 *
57 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
58 */
60 /*
61 * Lock ordering:
62 *
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
67 *
68 * ->i_mutex
69 * ->i_mmap_lock (truncate->unmap_mapping_range)
70 *
71 * ->mmap_sem
72 * ->i_mmap_lock
73 * ->page_table_lock or pte_lock (various, mainly in memory.c)
74 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
75 *
76 * ->mmap_sem
77 * ->lock_page (access_process_vm)
78 *
79 * ->mmap_sem
80 * ->i_mutex (msync)
81 *
82 * ->i_mutex
83 * ->i_alloc_sem (various)
84 *
85 * ->inode_lock
86 * ->sb_lock (fs/fs-writeback.c)
87 * ->mapping->tree_lock (__sync_single_inode)
88 *
89 * ->i_mmap_lock
90 * ->anon_vma.lock (vma_adjust)
91 *
92 * ->anon_vma.lock
93 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
94 *
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)
106 *
107 * ->task->proc_lock
108 * ->dcache_lock (proc_pid_lookup)
109 */
111 /*
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.
115 */
116 void __remove_from_page_cache(struct page *page)
117 {
118 struct address_space *mapping = page->mapping;
120 /*
121 * if we're uptodate, flush out into the precache, otherwise
122 * invalidate any existing precache entries. We can't leave
123 * stale data around in the precache once our page is gone
124 */
125 if (PageUptodate(page))
126 precache_put(page->mapping, page->index, page);
127 else
128 precache_flush(page->mapping, page->index);
130 radix_tree_delete(&mapping->page_tree, page->index);
131 page->mapping = NULL;
132 mapping->nrpages--;
133 __dec_zone_page_state(page, NR_FILE_PAGES);
134 }
136 void remove_from_page_cache(struct page *page)
137 {
138 struct address_space *mapping = page->mapping;
140 BUG_ON(!PageLocked(page));
142 write_lock_irq(&mapping->tree_lock);
143 __remove_from_page_cache(page);
144 write_unlock_irq(&mapping->tree_lock);
145 }
147 static int sync_page(void *word)
148 {
149 struct address_space *mapping;
150 struct page *page;
152 page = container_of((unsigned long *)word, struct page, flags);
154 /*
155 * page_mapping() is being called without PG_locked held.
156 * Some knowledge of the state and use of the page is used to
157 * reduce the requirements down to a memory barrier.
158 * The danger here is of a stale page_mapping() return value
159 * indicating a struct address_space different from the one it's
160 * associated with when it is associated with one.
161 * After smp_mb(), it's either the correct page_mapping() for
162 * the page, or an old page_mapping() and the page's own
163 * page_mapping() has gone NULL.
164 * The ->sync_page() address_space operation must tolerate
165 * page_mapping() going NULL. By an amazing coincidence,
166 * this comes about because none of the users of the page
167 * in the ->sync_page() methods make essential use of the
168 * page_mapping(), merely passing the page down to the backing
169 * device's unplug functions when it's non-NULL, which in turn
170 * ignore it for all cases but swap, where only page_private(page) is
171 * of interest. When page_mapping() does go NULL, the entire
172 * call stack gracefully ignores the page and returns.
173 * -- wli
174 */
175 smp_mb();
176 mapping = page_mapping(page);
177 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
178 mapping->a_ops->sync_page(page);
179 io_schedule();
180 return 0;
181 }
183 /**
184 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
185 * @mapping: address space structure to write
186 * @start: offset in bytes where the range starts
187 * @end: offset in bytes where the range ends (inclusive)
188 * @sync_mode: enable synchronous operation
189 *
190 * Start writeback against all of a mapping's dirty pages that lie
191 * within the byte offsets <start, end> inclusive.
192 *
193 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
194 * opposed to a regular memory cleansing writeback. The difference between
195 * these two operations is that if a dirty page/buffer is encountered, it must
196 * be waited upon, and not just skipped over.
197 */
198 int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
199 loff_t end, int sync_mode)
200 {
201 int ret;
202 struct writeback_control wbc = {
203 .sync_mode = sync_mode,
204 .nr_to_write = mapping->nrpages * 2,
205 .range_start = start,
206 .range_end = end,
207 };
209 if (!mapping_cap_writeback_dirty(mapping))
210 return 0;
212 ret = do_writepages(mapping, &wbc);
213 return ret;
214 }
216 static inline int __filemap_fdatawrite(struct address_space *mapping,
217 int sync_mode)
218 {
219 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
220 }
222 int filemap_fdatawrite(struct address_space *mapping)
223 {
224 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
225 }
226 EXPORT_SYMBOL(filemap_fdatawrite);
228 static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
229 loff_t end)
230 {
231 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
232 }
234 /**
235 * filemap_flush - mostly a non-blocking flush
236 * @mapping: target address_space
237 *
238 * This is a mostly non-blocking flush. Not suitable for data-integrity
239 * purposes - I/O may not be started against all dirty pages.
240 */
241 int filemap_flush(struct address_space *mapping)
242 {
243 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
244 }
245 EXPORT_SYMBOL(filemap_flush);
247 /**
248 * wait_on_page_writeback_range - wait for writeback to complete
249 * @mapping: target address_space
250 * @start: beginning page index
251 * @end: ending page index
252 *
253 * Wait for writeback to complete against pages indexed by start->end
254 * inclusive
255 */
256 int wait_on_page_writeback_range(struct address_space *mapping,
257 pgoff_t start, pgoff_t end)
258 {
259 struct pagevec pvec;
260 int nr_pages;
261 int ret = 0;
262 pgoff_t index;
264 if (end < start)
265 return 0;
267 pagevec_init(&pvec, 0);
268 index = start;
269 while ((index <= end) &&
270 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
271 PAGECACHE_TAG_WRITEBACK,
272 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
273 unsigned i;
275 for (i = 0; i < nr_pages; i++) {
276 struct page *page = pvec.pages[i];
278 /* until radix tree lookup accepts end_index */
279 if (page->index > end)
280 continue;
282 wait_on_page_writeback(page);
283 if (PageError(page))
284 ret = -EIO;
285 }
286 pagevec_release(&pvec);
287 cond_resched();
288 }
290 /* Check for outstanding write errors */
291 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
292 ret = -ENOSPC;
293 if (test_and_clear_bit(AS_EIO, &mapping->flags))
294 ret = -EIO;
296 return ret;
297 }
299 /**
300 * sync_page_range - write and wait on all pages in the passed range
301 * @inode: target inode
302 * @mapping: target address_space
303 * @pos: beginning offset in pages to write
304 * @count: number of bytes to write
305 *
306 * Write and wait upon all the pages in the passed range. This is a "data
307 * integrity" operation. It waits upon in-flight writeout before starting and
308 * waiting upon new writeout. If there was an IO error, return it.
309 *
310 * We need to re-take i_mutex during the generic_osync_inode list walk because
311 * it is otherwise livelockable.
312 */
313 int sync_page_range(struct inode *inode, struct address_space *mapping,
314 loff_t pos, loff_t count)
315 {
316 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
317 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
318 int ret;
320 if (!mapping_cap_writeback_dirty(mapping) || !count)
321 return 0;
322 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
323 if (ret == 0) {
324 mutex_lock(&inode->i_mutex);
325 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
326 mutex_unlock(&inode->i_mutex);
327 }
328 if (ret == 0)
329 ret = wait_on_page_writeback_range(mapping, start, end);
330 return ret;
331 }
332 EXPORT_SYMBOL(sync_page_range);
334 /**
335 * sync_page_range_nolock
336 * @inode: target inode
337 * @mapping: target address_space
338 * @pos: beginning offset in pages to write
339 * @count: number of bytes to write
340 *
341 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
342 * as it forces O_SYNC writers to different parts of the same file
343 * to be serialised right until io completion.
344 */
345 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
346 loff_t pos, loff_t count)
347 {
348 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
349 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
350 int ret;
352 if (!mapping_cap_writeback_dirty(mapping) || !count)
353 return 0;
354 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
355 if (ret == 0)
356 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
357 if (ret == 0)
358 ret = wait_on_page_writeback_range(mapping, start, end);
359 return ret;
360 }
361 EXPORT_SYMBOL(sync_page_range_nolock);
363 /**
364 * filemap_fdatawait - wait for all under-writeback pages to complete
365 * @mapping: address space structure to wait for
366 *
367 * Walk the list of under-writeback pages of the given address space
368 * and wait for all of them.
369 */
370 int filemap_fdatawait(struct address_space *mapping)
371 {
372 loff_t i_size = i_size_read(mapping->host);
374 if (i_size == 0)
375 return 0;
377 return wait_on_page_writeback_range(mapping, 0,
378 (i_size - 1) >> PAGE_CACHE_SHIFT);
379 }
380 EXPORT_SYMBOL(filemap_fdatawait);
382 int filemap_write_and_wait(struct address_space *mapping)
383 {
384 int err = 0;
386 if (mapping->nrpages) {
387 err = filemap_fdatawrite(mapping);
388 /*
389 * Even if the above returned error, the pages may be
390 * written partially (e.g. -ENOSPC), so we wait for it.
391 * But the -EIO is special case, it may indicate the worst
392 * thing (e.g. bug) happened, so we avoid waiting for it.
393 */
394 if (err != -EIO) {
395 int err2 = filemap_fdatawait(mapping);
396 if (!err)
397 err = err2;
398 }
399 }
400 return err;
401 }
402 EXPORT_SYMBOL(filemap_write_and_wait);
404 /**
405 * filemap_write_and_wait_range - write out & wait on a file range
406 * @mapping: the address_space for the pages
407 * @lstart: offset in bytes where the range starts
408 * @lend: offset in bytes where the range ends (inclusive)
409 *
410 * Write out and wait upon file offsets lstart->lend, inclusive.
411 *
412 * Note that `lend' is inclusive (describes the last byte to be written) so
413 * that this function can be used to write to the very end-of-file (end = -1).
414 */
415 int filemap_write_and_wait_range(struct address_space *mapping,
416 loff_t lstart, loff_t lend)
417 {
418 int err = 0;
420 if (mapping->nrpages) {
421 err = __filemap_fdatawrite_range(mapping, lstart, lend,
422 WB_SYNC_ALL);
423 /* See comment of filemap_write_and_wait() */
424 if (err != -EIO) {
425 int err2 = wait_on_page_writeback_range(mapping,
426 lstart >> PAGE_CACHE_SHIFT,
427 lend >> PAGE_CACHE_SHIFT);
428 if (!err)
429 err = err2;
430 }
431 }
432 return err;
433 }
435 /**
436 * add_to_page_cache - add newly allocated pagecache pages
437 * @page: page to add
438 * @mapping: the page's address_space
439 * @offset: page index
440 * @gfp_mask: page allocation mode
441 *
442 * This function is used to add newly allocated pagecache pages;
443 * the page is new, so we can just run SetPageLocked() against it.
444 * The other page state flags were set by rmqueue().
445 *
446 * This function does not add the page to the LRU. The caller must do that.
447 */
448 int add_to_page_cache(struct page *page, struct address_space *mapping,
449 pgoff_t offset, gfp_t gfp_mask)
450 {
451 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
453 if (error == 0) {
454 write_lock_irq(&mapping->tree_lock);
455 error = radix_tree_insert(&mapping->page_tree, offset, page);
456 if (!error) {
457 page_cache_get(page);
458 SetPageLocked(page);
459 page->mapping = mapping;
460 page->index = offset;
461 mapping->nrpages++;
462 __inc_zone_page_state(page, NR_FILE_PAGES);
463 }
464 write_unlock_irq(&mapping->tree_lock);
465 radix_tree_preload_end();
466 }
467 return error;
468 }
469 EXPORT_SYMBOL(add_to_page_cache);
471 int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
472 pgoff_t offset, gfp_t gfp_mask)
473 {
474 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
475 if (ret == 0)
476 lru_cache_add(page);
477 return ret;
478 }
480 #ifdef CONFIG_NUMA
481 struct page *page_cache_alloc(struct address_space *x)
482 {
483 if (cpuset_do_page_mem_spread()) {
484 int n = cpuset_mem_spread_node();
485 return alloc_pages_node(n, mapping_gfp_mask(x), 0);
486 }
487 return alloc_pages(mapping_gfp_mask(x), 0);
488 }
489 EXPORT_SYMBOL(page_cache_alloc);
491 struct page *page_cache_alloc_cold(struct address_space *x)
492 {
493 if (cpuset_do_page_mem_spread()) {
494 int n = cpuset_mem_spread_node();
495 return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
496 }
497 return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
498 }
499 EXPORT_SYMBOL(page_cache_alloc_cold);
500 #endif
502 /*
503 * In order to wait for pages to become available there must be
504 * waitqueues associated with pages. By using a hash table of
505 * waitqueues where the bucket discipline is to maintain all
506 * waiters on the same queue and wake all when any of the pages
507 * become available, and for the woken contexts to check to be
508 * sure the appropriate page became available, this saves space
509 * at a cost of "thundering herd" phenomena during rare hash
510 * collisions.
511 */
512 static wait_queue_head_t *page_waitqueue(struct page *page)
513 {
514 const struct zone *zone = page_zone(page);
516 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
517 }
519 static inline void wake_up_page(struct page *page, int bit)
520 {
521 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
522 }
524 void fastcall wait_on_page_bit(struct page *page, int bit_nr)
525 {
526 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
528 if (test_bit(bit_nr, &page->flags))
529 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
530 TASK_UNINTERRUPTIBLE);
531 }
532 EXPORT_SYMBOL(wait_on_page_bit);
534 /**
535 * unlock_page - unlock a locked page
536 * @page: the page
537 *
538 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
539 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
540 * mechananism between PageLocked pages and PageWriteback pages is shared.
541 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
542 *
543 * The first mb is necessary to safely close the critical section opened by the
544 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
545 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
546 * parallel wait_on_page_locked()).
547 */
548 void fastcall unlock_page(struct page *page)
549 {
550 smp_mb__before_clear_bit();
551 if (!TestClearPageLocked(page))
552 BUG();
553 smp_mb__after_clear_bit();
554 wake_up_page(page, PG_locked);
555 }
556 EXPORT_SYMBOL(unlock_page);
558 /**
559 * end_page_writeback - end writeback against a page
560 * @page: the page
561 */
562 void end_page_writeback(struct page *page)
563 {
564 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
565 if (!test_clear_page_writeback(page))
566 BUG();
567 }
568 smp_mb__after_clear_bit();
569 wake_up_page(page, PG_writeback);
570 }
571 EXPORT_SYMBOL(end_page_writeback);
573 /**
574 * __lock_page - get a lock on the page, assuming we need to sleep to get it
575 * @page: the page to lock
576 *
577 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
578 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
579 * chances are that on the second loop, the block layer's plug list is empty,
580 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
581 */
582 void fastcall __lock_page(struct page *page)
583 {
584 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
586 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
587 TASK_UNINTERRUPTIBLE);
588 }
589 EXPORT_SYMBOL(__lock_page);
591 /**
592 * find_get_page - find and get a page reference
593 * @mapping: the address_space to search
594 * @offset: the page index
595 *
596 * A rather lightweight function, finding and getting a reference to a
597 * hashed page atomically.
598 */
599 struct page * find_get_page(struct address_space *mapping, unsigned long offset)
600 {
601 struct page *page;
603 read_lock_irq(&mapping->tree_lock);
604 page = radix_tree_lookup(&mapping->page_tree, offset);
605 if (page)
606 page_cache_get(page);
607 read_unlock_irq(&mapping->tree_lock);
608 return page;
609 }
610 EXPORT_SYMBOL(find_get_page);
612 /**
613 * find_trylock_page - find and lock a page
614 * @mapping: the address_space to search
615 * @offset: the page index
616 *
617 * Same as find_get_page(), but trylock it instead of incrementing the count.
618 */
619 struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
620 {
621 struct page *page;
623 read_lock_irq(&mapping->tree_lock);
624 page = radix_tree_lookup(&mapping->page_tree, offset);
625 if (page && TestSetPageLocked(page))
626 page = NULL;
627 read_unlock_irq(&mapping->tree_lock);
628 return page;
629 }
630 EXPORT_SYMBOL(find_trylock_page);
632 /**
633 * find_lock_page - locate, pin and lock a pagecache page
634 * @mapping: the address_space to search
635 * @offset: the page index
636 *
637 * Locates the desired pagecache page, locks it, increments its reference
638 * count and returns its address.
639 *
640 * Returns zero if the page was not present. find_lock_page() may sleep.
641 */
642 struct page *find_lock_page(struct address_space *mapping,
643 unsigned long offset)
644 {
645 struct page *page;
647 read_lock_irq(&mapping->tree_lock);
648 repeat:
649 page = radix_tree_lookup(&mapping->page_tree, offset);
650 if (page) {
651 page_cache_get(page);
652 if (TestSetPageLocked(page)) {
653 read_unlock_irq(&mapping->tree_lock);
654 __lock_page(page);
655 read_lock_irq(&mapping->tree_lock);
657 /* Has the page been truncated while we slept? */
658 if (unlikely(page->mapping != mapping ||
659 page->index != offset)) {
660 unlock_page(page);
661 page_cache_release(page);
662 goto repeat;
663 }
664 }
665 }
666 read_unlock_irq(&mapping->tree_lock);
667 return page;
668 }
669 EXPORT_SYMBOL(find_lock_page);
671 /**
672 * find_or_create_page - locate or add a pagecache page
673 * @mapping: the page's address_space
674 * @index: the page's index into the mapping
675 * @gfp_mask: page allocation mode
676 *
677 * Locates a page in the pagecache. If the page is not present, a new page
678 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
679 * LRU list. The returned page is locked and has its reference count
680 * incremented.
681 *
682 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
683 * allocation!
684 *
685 * find_or_create_page() returns the desired page's address, or zero on
686 * memory exhaustion.
687 */
688 struct page *find_or_create_page(struct address_space *mapping,
689 unsigned long index, gfp_t gfp_mask)
690 {
691 struct page *page, *cached_page = NULL;
692 int err;
693 repeat:
694 page = find_lock_page(mapping, index);
695 if (!page) {
696 if (!cached_page) {
697 cached_page = alloc_page(gfp_mask);
698 if (!cached_page)
699 return NULL;
700 }
701 err = add_to_page_cache_lru(cached_page, mapping,
702 index, gfp_mask);
703 if (!err) {
704 page = cached_page;
705 cached_page = NULL;
706 } else if (err == -EEXIST)
707 goto repeat;
708 }
709 if (cached_page)
710 page_cache_release(cached_page);
711 return page;
712 }
713 EXPORT_SYMBOL(find_or_create_page);
715 /**
716 * find_get_pages - gang pagecache lookup
717 * @mapping: The address_space to search
718 * @start: The starting page index
719 * @nr_pages: The maximum number of pages
720 * @pages: Where the resulting pages are placed
721 *
722 * find_get_pages() will search for and return a group of up to
723 * @nr_pages pages in the mapping. The pages are placed at @pages.
724 * find_get_pages() takes a reference against the returned pages.
725 *
726 * The search returns a group of mapping-contiguous pages with ascending
727 * indexes. There may be holes in the indices due to not-present pages.
728 *
729 * find_get_pages() returns the number of pages which were found.
730 */
731 unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
732 unsigned int nr_pages, struct page **pages)
733 {
734 unsigned int i;
735 unsigned int ret;
737 read_lock_irq(&mapping->tree_lock);
738 ret = radix_tree_gang_lookup(&mapping->page_tree,
739 (void **)pages, start, nr_pages);
740 for (i = 0; i < ret; i++)
741 page_cache_get(pages[i]);
742 read_unlock_irq(&mapping->tree_lock);
743 return ret;
744 }
746 /**
747 * find_get_pages_contig - gang contiguous pagecache lookup
748 * @mapping: The address_space to search
749 * @index: The starting page index
750 * @nr_pages: The maximum number of pages
751 * @pages: Where the resulting pages are placed
752 *
753 * find_get_pages_contig() works exactly like find_get_pages(), except
754 * that the returned number of pages are guaranteed to be contiguous.
755 *
756 * find_get_pages_contig() returns the number of pages which were found.
757 */
758 unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
759 unsigned int nr_pages, struct page **pages)
760 {
761 unsigned int i;
762 unsigned int ret;
764 read_lock_irq(&mapping->tree_lock);
765 ret = radix_tree_gang_lookup(&mapping->page_tree,
766 (void **)pages, index, nr_pages);
767 for (i = 0; i < ret; i++) {
768 if (pages[i]->mapping == NULL || pages[i]->index != index)
769 break;
771 page_cache_get(pages[i]);
772 index++;
773 }
774 read_unlock_irq(&mapping->tree_lock);
775 return i;
776 }
778 /**
779 * find_get_pages_tag - find and return pages that match @tag
780 * @mapping: the address_space to search
781 * @index: the starting page index
782 * @tag: the tag index
783 * @nr_pages: the maximum number of pages
784 * @pages: where the resulting pages are placed
785 *
786 * Like find_get_pages, except we only return pages which are tagged with
787 * @tag. We update @index to index the next page for the traversal.
788 */
789 unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
790 int tag, unsigned int nr_pages, struct page **pages)
791 {
792 unsigned int i;
793 unsigned int ret;
795 read_lock_irq(&mapping->tree_lock);
796 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
797 (void **)pages, *index, nr_pages, tag);
798 for (i = 0; i < ret; i++)
799 page_cache_get(pages[i]);
800 if (ret)
801 *index = pages[ret - 1]->index + 1;
802 read_unlock_irq(&mapping->tree_lock);
803 return ret;
804 }
806 /**
807 * grab_cache_page_nowait - returns locked page at given index in given cache
808 * @mapping: target address_space
809 * @index: the page index
810 *
811 * Same as grab_cache_page, but do not wait if the page is unavailable.
812 * This is intended for speculative data generators, where the data can
813 * be regenerated if the page couldn't be grabbed. This routine should
814 * be safe to call while holding the lock for another page.
815 *
816 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
817 * and deadlock against the caller's locked page.
818 */
819 struct page *
820 grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
821 {
822 struct page *page = find_get_page(mapping, index);
823 gfp_t gfp_mask;
825 if (page) {
826 if (!TestSetPageLocked(page))
827 return page;
828 page_cache_release(page);
829 return NULL;
830 }
831 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
832 page = alloc_pages(gfp_mask, 0);
833 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
834 page_cache_release(page);
835 page = NULL;
836 }
837 return page;
838 }
839 EXPORT_SYMBOL(grab_cache_page_nowait);
841 /*
842 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
843 * a _large_ part of the i/o request. Imagine the worst scenario:
844 *
845 * ---R__________________________________________B__________
846 * ^ reading here ^ bad block(assume 4k)
847 *
848 * read(R) => miss => readahead(R...B) => media error => frustrating retries
849 * => failing the whole request => read(R) => read(R+1) =>
850 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
851 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
852 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
853 *
854 * It is going insane. Fix it by quickly scaling down the readahead size.
855 */
856 static void shrink_readahead_size_eio(struct file *filp,
857 struct file_ra_state *ra)
858 {
859 if (!ra->ra_pages)
860 return;
862 ra->ra_pages /= 4;
863 }
865 /**
866 * do_generic_mapping_read - generic file read routine
867 * @mapping: address_space to be read
868 * @_ra: file's readahead state
869 * @filp: the file to read
870 * @ppos: current file position
871 * @desc: read_descriptor
872 * @actor: read method
873 *
874 * This is a generic file read routine, and uses the
875 * mapping->a_ops->readpage() function for the actual low-level stuff.
876 *
877 * This is really ugly. But the goto's actually try to clarify some
878 * of the logic when it comes to error handling etc.
879 *
880 * Note the struct file* is only passed for the use of readpage.
881 * It may be NULL.
882 */
883 void do_generic_mapping_read(struct address_space *mapping,
884 struct file_ra_state *_ra,
885 struct file *filp,
886 loff_t *ppos,
887 read_descriptor_t *desc,
888 read_actor_t actor)
889 {
890 struct inode *inode = mapping->host;
891 unsigned long index;
892 unsigned long end_index;
893 unsigned long offset;
894 unsigned long last_index;
895 unsigned long next_index;
896 unsigned long prev_index;
897 loff_t isize;
898 struct page *cached_page;
899 int error;
900 struct file_ra_state ra = *_ra;
902 cached_page = NULL;
903 index = *ppos >> PAGE_CACHE_SHIFT;
904 next_index = index;
905 prev_index = ra.prev_page;
906 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
907 offset = *ppos & ~PAGE_CACHE_MASK;
909 isize = i_size_read(inode);
910 if (!isize)
911 goto out;
913 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
914 for (;;) {
915 struct page *page;
916 unsigned long nr, ret;
918 /* nr is the maximum number of bytes to copy from this page */
919 nr = PAGE_CACHE_SIZE;
920 if (index >= end_index) {
921 if (index > end_index)
922 goto out;
923 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
924 if (nr <= offset) {
925 goto out;
926 }
927 }
928 nr = nr - offset;
930 cond_resched();
931 if (index == next_index)
932 next_index = page_cache_readahead(mapping, &ra, filp,
933 index, last_index - index);
935 find_page:
936 page = find_get_page(mapping, index);
937 if (unlikely(page == NULL)) {
938 handle_ra_miss(mapping, &ra, index);
939 goto no_cached_page;
940 }
941 if (!PageUptodate(page))
942 goto page_not_up_to_date;
943 page_ok:
945 /* If users can be writing to this page using arbitrary
946 * virtual addresses, take care about potential aliasing
947 * before reading the page on the kernel side.
948 */
949 if (mapping_writably_mapped(mapping))
950 flush_dcache_page(page);
952 /*
953 * When (part of) the same page is read multiple times
954 * in succession, only mark it as accessed the first time.
955 */
956 if (prev_index != index)
957 mark_page_accessed(page);
958 prev_index = index;
960 /*
961 * Ok, we have the page, and it's up-to-date, so
962 * now we can copy it to user space...
963 *
964 * The actor routine returns how many bytes were actually used..
965 * NOTE! This may not be the same as how much of a user buffer
966 * we filled up (we may be padding etc), so we can only update
967 * "pos" here (the actor routine has to update the user buffer
968 * pointers and the remaining count).
969 */
970 ret = actor(desc, page, offset, nr);
971 offset += ret;
972 index += offset >> PAGE_CACHE_SHIFT;
973 offset &= ~PAGE_CACHE_MASK;
975 page_cache_release(page);
976 if (ret == nr && desc->count)
977 continue;
978 goto out;
980 page_not_up_to_date:
981 /* Get exclusive access to the page ... */
982 lock_page(page);
984 /* Did it get unhashed before we got the lock? */
985 if (!page->mapping) {
986 unlock_page(page);
987 page_cache_release(page);
988 continue;
989 }
991 /* Did somebody else fill it already? */
992 if (PageUptodate(page)) {
993 unlock_page(page);
994 goto page_ok;
995 }
997 readpage:
998 /* Start the actual read. The read will unlock the page. */
999 error = mapping->a_ops->readpage(filp, page);
1001 if (unlikely(error)) {
1002 if (error == AOP_TRUNCATED_PAGE) {
1003 page_cache_release(page);
1004 goto find_page;
1006 goto readpage_error;
1009 if (!PageUptodate(page)) {
1010 lock_page(page);
1011 if (!PageUptodate(page)) {
1012 if (page->mapping == NULL) {
1013 /*
1014 * invalidate_inode_pages got it
1015 */
1016 unlock_page(page);
1017 page_cache_release(page);
1018 goto find_page;
1020 unlock_page(page);
1021 error = -EIO;
1022 shrink_readahead_size_eio(filp, &ra);
1023 goto readpage_error;
1025 unlock_page(page);
1028 /*
1029 * i_size must be checked after we have done ->readpage.
1031 * Checking i_size after the readpage allows us to calculate
1032 * the correct value for "nr", which means the zero-filled
1033 * part of the page is not copied back to userspace (unless
1034 * another truncate extends the file - this is desired though).
1035 */
1036 isize = i_size_read(inode);
1037 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1038 if (unlikely(!isize || index > end_index)) {
1039 page_cache_release(page);
1040 goto out;
1043 /* nr is the maximum number of bytes to copy from this page */
1044 nr = PAGE_CACHE_SIZE;
1045 if (index == end_index) {
1046 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1047 if (nr <= offset) {
1048 page_cache_release(page);
1049 goto out;
1052 nr = nr - offset;
1053 goto page_ok;
1055 readpage_error:
1056 /* UHHUH! A synchronous read error occurred. Report it */
1057 desc->error = error;
1058 page_cache_release(page);
1059 goto out;
1061 no_cached_page:
1062 /*
1063 * Ok, it wasn't cached, so we need to create a new
1064 * page..
1065 */
1066 if (!cached_page) {
1067 cached_page = page_cache_alloc_cold(mapping);
1068 if (!cached_page) {
1069 desc->error = -ENOMEM;
1070 goto out;
1073 error = add_to_page_cache_lru(cached_page, mapping,
1074 index, GFP_KERNEL);
1075 if (error) {
1076 if (error == -EEXIST)
1077 goto find_page;
1078 desc->error = error;
1079 goto out;
1081 page = cached_page;
1082 cached_page = NULL;
1083 goto readpage;
1086 out:
1087 *_ra = ra;
1089 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1090 if (cached_page)
1091 page_cache_release(cached_page);
1092 if (filp)
1093 file_accessed(filp);
1095 EXPORT_SYMBOL(do_generic_mapping_read);
1097 int file_read_actor(read_descriptor_t *desc, struct page *page,
1098 unsigned long offset, unsigned long size)
1100 char *kaddr;
1101 unsigned long left, count = desc->count;
1103 if (size > count)
1104 size = count;
1106 /*
1107 * Faults on the destination of a read are common, so do it before
1108 * taking the kmap.
1109 */
1110 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1111 kaddr = kmap_atomic(page, KM_USER0);
1112 left = __copy_to_user_inatomic(desc->arg.buf,
1113 kaddr + offset, size);
1114 kunmap_atomic(kaddr, KM_USER0);
1115 if (left == 0)
1116 goto success;
1119 /* Do it the slow way */
1120 kaddr = kmap(page);
1121 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1122 kunmap(page);
1124 if (left) {
1125 size -= left;
1126 desc->error = -EFAULT;
1128 success:
1129 desc->count = count - size;
1130 desc->written += size;
1131 desc->arg.buf += size;
1132 return size;
1135 /**
1136 * __generic_file_aio_read - generic filesystem read routine
1137 * @iocb: kernel I/O control block
1138 * @iov: io vector request
1139 * @nr_segs: number of segments in the iovec
1140 * @ppos: current file position
1142 * This is the "read()" routine for all filesystems
1143 * that can use the page cache directly.
1144 */
1145 ssize_t
1146 __generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1147 unsigned long nr_segs, loff_t *ppos)
1149 struct file *filp = iocb->ki_filp;
1150 ssize_t retval;
1151 unsigned long seg;
1152 size_t count;
1154 count = 0;
1155 for (seg = 0; seg < nr_segs; seg++) {
1156 const struct iovec *iv = &iov[seg];
1158 /*
1159 * If any segment has a negative length, or the cumulative
1160 * length ever wraps negative then return -EINVAL.
1161 */
1162 count += iv->iov_len;
1163 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1164 return -EINVAL;
1165 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1166 continue;
1167 if (seg == 0)
1168 return -EFAULT;
1169 nr_segs = seg;
1170 count -= iv->iov_len; /* This segment is no good */
1171 break;
1174 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1175 if (filp->f_flags & O_DIRECT) {
1176 loff_t pos = *ppos, size;
1177 struct address_space *mapping;
1178 struct inode *inode;
1180 mapping = filp->f_mapping;
1181 inode = mapping->host;
1182 retval = 0;
1183 if (!count)
1184 goto out; /* skip atime */
1185 size = i_size_read(inode);
1186 if (pos < size) {
1187 retval = generic_file_direct_IO(READ, iocb,
1188 iov, pos, nr_segs);
1189 if (retval > 0 && !is_sync_kiocb(iocb))
1190 retval = -EIOCBQUEUED;
1191 if (retval > 0)
1192 *ppos = pos + retval;
1194 file_accessed(filp);
1195 goto out;
1198 retval = 0;
1199 if (count) {
1200 for (seg = 0; seg < nr_segs; seg++) {
1201 read_descriptor_t desc;
1203 desc.written = 0;
1204 desc.arg.buf = iov[seg].iov_base;
1205 desc.count = iov[seg].iov_len;
1206 if (desc.count == 0)
1207 continue;
1208 desc.error = 0;
1209 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1210 retval += desc.written;
1211 if (desc.error) {
1212 retval = retval ?: desc.error;
1213 break;
1217 out:
1218 return retval;
1220 EXPORT_SYMBOL(__generic_file_aio_read);
1222 ssize_t
1223 generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1225 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1227 BUG_ON(iocb->ki_pos != pos);
1228 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1230 EXPORT_SYMBOL(generic_file_aio_read);
1232 ssize_t
1233 generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1235 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1236 struct kiocb kiocb;
1237 ssize_t ret;
1239 init_sync_kiocb(&kiocb, filp);
1240 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1241 if (-EIOCBQUEUED == ret)
1242 ret = wait_on_sync_kiocb(&kiocb);
1243 return ret;
1245 EXPORT_SYMBOL(generic_file_read);
1247 int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1249 ssize_t written;
1250 unsigned long count = desc->count;
1251 struct file *file = desc->arg.data;
1253 if (size > count)
1254 size = count;
1256 written = file->f_op->sendpage(file, page, offset,
1257 size, &file->f_pos, size<count);
1258 if (written < 0) {
1259 desc->error = written;
1260 written = 0;
1262 desc->count = count - written;
1263 desc->written += written;
1264 return written;
1267 ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1268 size_t count, read_actor_t actor, void *target)
1270 read_descriptor_t desc;
1272 if (!count)
1273 return 0;
1275 desc.written = 0;
1276 desc.count = count;
1277 desc.arg.data = target;
1278 desc.error = 0;
1280 do_generic_file_read(in_file, ppos, &desc, actor);
1281 if (desc.written)
1282 return desc.written;
1283 return desc.error;
1285 EXPORT_SYMBOL(generic_file_sendfile);
1287 static ssize_t
1288 do_readahead(struct address_space *mapping, struct file *filp,
1289 unsigned long index, unsigned long nr)
1291 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1292 return -EINVAL;
1294 force_page_cache_readahead(mapping, filp, index,
1295 max_sane_readahead(nr));
1296 return 0;
1299 asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1301 ssize_t ret;
1302 struct file *file;
1304 ret = -EBADF;
1305 file = fget(fd);
1306 if (file) {
1307 if (file->f_mode & FMODE_READ) {
1308 struct address_space *mapping = file->f_mapping;
1309 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1310 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1311 unsigned long len = end - start + 1;
1312 ret = do_readahead(mapping, file, start, len);
1314 fput(file);
1316 return ret;
1319 #ifdef CONFIG_MMU
1320 static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1321 /**
1322 * page_cache_read - adds requested page to the page cache if not already there
1323 * @file: file to read
1324 * @offset: page index
1326 * This adds the requested page to the page cache if it isn't already there,
1327 * and schedules an I/O to read in its contents from disk.
1328 */
1329 static int fastcall page_cache_read(struct file * file, unsigned long offset)
1331 struct address_space *mapping = file->f_mapping;
1332 struct page *page;
1333 int ret;
1335 do {
1336 page = page_cache_alloc_cold(mapping);
1337 if (!page)
1338 return -ENOMEM;
1340 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1341 if (ret == 0)
1342 ret = mapping->a_ops->readpage(file, page);
1343 else if (ret == -EEXIST)
1344 ret = 0; /* losing race to add is OK */
1346 page_cache_release(page);
1348 } while (ret == AOP_TRUNCATED_PAGE);
1350 return ret;
1353 #define MMAP_LOTSAMISS (100)
1355 /**
1356 * filemap_nopage - read in file data for page fault handling
1357 * @area: the applicable vm_area
1358 * @address: target address to read in
1359 * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1361 * filemap_nopage() is invoked via the vma operations vector for a
1362 * mapped memory region to read in file data during a page fault.
1364 * The goto's are kind of ugly, but this streamlines the normal case of having
1365 * it in the page cache, and handles the special cases reasonably without
1366 * having a lot of duplicated code.
1367 */
1368 struct page *filemap_nopage(struct vm_area_struct *area,
1369 unsigned long address, int *type)
1371 int error;
1372 struct file *file = area->vm_file;
1373 struct address_space *mapping = file->f_mapping;
1374 struct file_ra_state *ra = &file->f_ra;
1375 struct inode *inode = mapping->host;
1376 struct page *page;
1377 unsigned long size, pgoff;
1378 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1380 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1382 retry_all:
1383 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1384 if (pgoff >= size)
1385 goto outside_data_content;
1387 /* If we don't want any read-ahead, don't bother */
1388 if (VM_RandomReadHint(area))
1389 goto no_cached_page;
1391 /*
1392 * The readahead code wants to be told about each and every page
1393 * so it can build and shrink its windows appropriately
1395 * For sequential accesses, we use the generic readahead logic.
1396 */
1397 if (VM_SequentialReadHint(area))
1398 page_cache_readahead(mapping, ra, file, pgoff, 1);
1400 /*
1401 * Do we have something in the page cache already?
1402 */
1403 retry_find:
1404 page = find_get_page(mapping, pgoff);
1405 if (!page) {
1406 unsigned long ra_pages;
1408 if (VM_SequentialReadHint(area)) {
1409 handle_ra_miss(mapping, ra, pgoff);
1410 goto no_cached_page;
1412 ra->mmap_miss++;
1414 /*
1415 * Do we miss much more than hit in this file? If so,
1416 * stop bothering with read-ahead. It will only hurt.
1417 */
1418 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1419 goto no_cached_page;
1421 /*
1422 * To keep the pgmajfault counter straight, we need to
1423 * check did_readaround, as this is an inner loop.
1424 */
1425 if (!did_readaround) {
1426 majmin = VM_FAULT_MAJOR;
1427 count_vm_event(PGMAJFAULT);
1429 did_readaround = 1;
1430 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1431 if (ra_pages) {
1432 pgoff_t start = 0;
1434 if (pgoff > ra_pages / 2)
1435 start = pgoff - ra_pages / 2;
1436 do_page_cache_readahead(mapping, file, start, ra_pages);
1438 page = find_get_page(mapping, pgoff);
1439 if (!page)
1440 goto no_cached_page;
1443 if (!did_readaround)
1444 ra->mmap_hit++;
1446 /*
1447 * Ok, found a page in the page cache, now we need to check
1448 * that it's up-to-date.
1449 */
1450 if (!PageUptodate(page))
1451 goto page_not_uptodate;
1453 success:
1454 /*
1455 * Found the page and have a reference on it.
1456 */
1457 mark_page_accessed(page);
1458 if (type)
1459 *type = majmin;
1460 return page;
1462 outside_data_content:
1463 /*
1464 * An external ptracer can access pages that normally aren't
1465 * accessible..
1466 */
1467 if (area->vm_mm == current->mm)
1468 return NULL;
1469 /* Fall through to the non-read-ahead case */
1470 no_cached_page:
1471 /*
1472 * We're only likely to ever get here if MADV_RANDOM is in
1473 * effect.
1474 */
1475 error = page_cache_read(file, pgoff);
1476 grab_swap_token();
1478 /*
1479 * The page we want has now been added to the page cache.
1480 * In the unlikely event that someone removed it in the
1481 * meantime, we'll just come back here and read it again.
1482 */
1483 if (error >= 0)
1484 goto retry_find;
1486 /*
1487 * An error return from page_cache_read can result if the
1488 * system is low on memory, or a problem occurs while trying
1489 * to schedule I/O.
1490 */
1491 if (error == -ENOMEM)
1492 return NOPAGE_OOM;
1493 return NULL;
1495 page_not_uptodate:
1496 if (!did_readaround) {
1497 majmin = VM_FAULT_MAJOR;
1498 count_vm_event(PGMAJFAULT);
1500 lock_page(page);
1502 /* Did it get unhashed while we waited for it? */
1503 if (!page->mapping) {
1504 unlock_page(page);
1505 page_cache_release(page);
1506 goto retry_all;
1509 /* Did somebody else get it up-to-date? */
1510 if (PageUptodate(page)) {
1511 unlock_page(page);
1512 goto success;
1515 error = mapping->a_ops->readpage(file, page);
1516 if (!error) {
1517 wait_on_page_locked(page);
1518 if (PageUptodate(page))
1519 goto success;
1520 } else if (error == AOP_TRUNCATED_PAGE) {
1521 page_cache_release(page);
1522 goto retry_find;
1525 /*
1526 * Umm, take care of errors if the page isn't up-to-date.
1527 * Try to re-read it _once_. We do this synchronously,
1528 * because there really aren't any performance issues here
1529 * and we need to check for errors.
1530 */
1531 lock_page(page);
1533 /* Somebody truncated the page on us? */
1534 if (!page->mapping) {
1535 unlock_page(page);
1536 page_cache_release(page);
1537 goto retry_all;
1540 /* Somebody else successfully read it in? */
1541 if (PageUptodate(page)) {
1542 unlock_page(page);
1543 goto success;
1545 ClearPageError(page);
1546 error = mapping->a_ops->readpage(file, page);
1547 if (!error) {
1548 wait_on_page_locked(page);
1549 if (PageUptodate(page))
1550 goto success;
1551 } else if (error == AOP_TRUNCATED_PAGE) {
1552 page_cache_release(page);
1553 goto retry_find;
1556 /*
1557 * Things didn't work out. Return zero to tell the
1558 * mm layer so, possibly freeing the page cache page first.
1559 */
1560 shrink_readahead_size_eio(file, ra);
1561 page_cache_release(page);
1562 return NULL;
1564 EXPORT_SYMBOL(filemap_nopage);
1566 static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1567 int nonblock)
1569 struct address_space *mapping = file->f_mapping;
1570 struct page *page;
1571 int error;
1573 /*
1574 * Do we have something in the page cache already?
1575 */
1576 retry_find:
1577 page = find_get_page(mapping, pgoff);
1578 if (!page) {
1579 if (nonblock)
1580 return NULL;
1581 goto no_cached_page;
1584 /*
1585 * Ok, found a page in the page cache, now we need to check
1586 * that it's up-to-date.
1587 */
1588 if (!PageUptodate(page)) {
1589 if (nonblock) {
1590 page_cache_release(page);
1591 return NULL;
1593 goto page_not_uptodate;
1596 success:
1597 /*
1598 * Found the page and have a reference on it.
1599 */
1600 mark_page_accessed(page);
1601 return page;
1603 no_cached_page:
1604 error = page_cache_read(file, pgoff);
1606 /*
1607 * The page we want has now been added to the page cache.
1608 * In the unlikely event that someone removed it in the
1609 * meantime, we'll just come back here and read it again.
1610 */
1611 if (error >= 0)
1612 goto retry_find;
1614 /*
1615 * An error return from page_cache_read can result if the
1616 * system is low on memory, or a problem occurs while trying
1617 * to schedule I/O.
1618 */
1619 return NULL;
1621 page_not_uptodate:
1622 lock_page(page);
1624 /* Did it get unhashed while we waited for it? */
1625 if (!page->mapping) {
1626 unlock_page(page);
1627 goto err;
1630 /* Did somebody else get it up-to-date? */
1631 if (PageUptodate(page)) {
1632 unlock_page(page);
1633 goto success;
1636 error = mapping->a_ops->readpage(file, page);
1637 if (!error) {
1638 wait_on_page_locked(page);
1639 if (PageUptodate(page))
1640 goto success;
1641 } else if (error == AOP_TRUNCATED_PAGE) {
1642 page_cache_release(page);
1643 goto retry_find;
1646 /*
1647 * Umm, take care of errors if the page isn't up-to-date.
1648 * Try to re-read it _once_. We do this synchronously,
1649 * because there really aren't any performance issues here
1650 * and we need to check for errors.
1651 */
1652 lock_page(page);
1654 /* Somebody truncated the page on us? */
1655 if (!page->mapping) {
1656 unlock_page(page);
1657 goto err;
1659 /* Somebody else successfully read it in? */
1660 if (PageUptodate(page)) {
1661 unlock_page(page);
1662 goto success;
1665 ClearPageError(page);
1666 error = mapping->a_ops->readpage(file, page);
1667 if (!error) {
1668 wait_on_page_locked(page);
1669 if (PageUptodate(page))
1670 goto success;
1671 } else if (error == AOP_TRUNCATED_PAGE) {
1672 page_cache_release(page);
1673 goto retry_find;
1676 /*
1677 * Things didn't work out. Return zero to tell the
1678 * mm layer so, possibly freeing the page cache page first.
1679 */
1680 err:
1681 page_cache_release(page);
1683 return NULL;
1686 int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1687 unsigned long len, pgprot_t prot, unsigned long pgoff,
1688 int nonblock)
1690 struct file *file = vma->vm_file;
1691 struct address_space *mapping = file->f_mapping;
1692 struct inode *inode = mapping->host;
1693 unsigned long size;
1694 struct mm_struct *mm = vma->vm_mm;
1695 struct page *page;
1696 int err;
1698 if (!nonblock)
1699 force_page_cache_readahead(mapping, vma->vm_file,
1700 pgoff, len >> PAGE_CACHE_SHIFT);
1702 repeat:
1703 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1704 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1705 return -EINVAL;
1707 page = filemap_getpage(file, pgoff, nonblock);
1709 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1710 * done in shmem_populate calling shmem_getpage */
1711 if (!page && !nonblock)
1712 return -ENOMEM;
1714 if (page) {
1715 err = install_page(mm, vma, addr, page, prot);
1716 if (err) {
1717 page_cache_release(page);
1718 return err;
1720 } else if (vma->vm_flags & VM_NONLINEAR) {
1721 /* No page was found just because we can't read it in now (being
1722 * here implies nonblock != 0), but the page may exist, so set
1723 * the PTE to fault it in later. */
1724 err = install_file_pte(mm, vma, addr, pgoff, prot);
1725 if (err)
1726 return err;
1729 len -= PAGE_SIZE;
1730 addr += PAGE_SIZE;
1731 pgoff++;
1732 if (len)
1733 goto repeat;
1735 return 0;
1737 EXPORT_SYMBOL(filemap_populate);
1739 struct vm_operations_struct generic_file_vm_ops = {
1740 .nopage = filemap_nopage,
1741 .populate = filemap_populate,
1742 };
1744 /* This is used for a general mmap of a disk file */
1746 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1748 struct address_space *mapping = file->f_mapping;
1750 if (!mapping->a_ops->readpage)
1751 return -ENOEXEC;
1752 file_accessed(file);
1753 vma->vm_ops = &generic_file_vm_ops;
1754 return 0;
1757 /*
1758 * This is for filesystems which do not implement ->writepage.
1759 */
1760 int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1762 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1763 return -EINVAL;
1764 return generic_file_mmap(file, vma);
1766 #else
1767 int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1769 return -ENOSYS;
1771 int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1773 return -ENOSYS;
1775 #endif /* CONFIG_MMU */
1777 EXPORT_SYMBOL(generic_file_mmap);
1778 EXPORT_SYMBOL(generic_file_readonly_mmap);
1780 static inline struct page *__read_cache_page(struct address_space *mapping,
1781 unsigned long index,
1782 int (*filler)(void *,struct page*),
1783 void *data)
1785 struct page *page, *cached_page = NULL;
1786 int err;
1787 repeat:
1788 page = find_get_page(mapping, index);
1789 if (!page) {
1790 if (!cached_page) {
1791 cached_page = page_cache_alloc_cold(mapping);
1792 if (!cached_page)
1793 return ERR_PTR(-ENOMEM);
1795 err = add_to_page_cache_lru(cached_page, mapping,
1796 index, GFP_KERNEL);
1797 if (err == -EEXIST)
1798 goto repeat;
1799 if (err < 0) {
1800 /* Presumably ENOMEM for radix tree node */
1801 page_cache_release(cached_page);
1802 return ERR_PTR(err);
1804 page = cached_page;
1805 cached_page = NULL;
1806 err = filler(data, page);
1807 if (err < 0) {
1808 page_cache_release(page);
1809 page = ERR_PTR(err);
1812 if (cached_page)
1813 page_cache_release(cached_page);
1814 return page;
1817 /**
1818 * read_cache_page - read into page cache, fill it if needed
1819 * @mapping: the page's address_space
1820 * @index: the page index
1821 * @filler: function to perform the read
1822 * @data: destination for read data
1824 * Read into the page cache. If a page already exists,
1825 * and PageUptodate() is not set, try to fill the page.
1826 */
1827 struct page *read_cache_page(struct address_space *mapping,
1828 unsigned long index,
1829 int (*filler)(void *,struct page*),
1830 void *data)
1832 struct page *page;
1833 int err;
1835 retry:
1836 page = __read_cache_page(mapping, index, filler, data);
1837 if (IS_ERR(page))
1838 goto out;
1839 mark_page_accessed(page);
1840 if (PageUptodate(page))
1841 goto out;
1843 lock_page(page);
1844 if (!page->mapping) {
1845 unlock_page(page);
1846 page_cache_release(page);
1847 goto retry;
1849 if (PageUptodate(page)) {
1850 unlock_page(page);
1851 goto out;
1853 err = filler(data, page);
1854 if (err < 0) {
1855 page_cache_release(page);
1856 page = ERR_PTR(err);
1858 out:
1859 return page;
1861 EXPORT_SYMBOL(read_cache_page);
1863 /*
1864 * If the page was newly created, increment its refcount and add it to the
1865 * caller's lru-buffering pagevec. This function is specifically for
1866 * generic_file_write().
1867 */
1868 static inline struct page *
1869 __grab_cache_page(struct address_space *mapping, unsigned long index,
1870 struct page **cached_page, struct pagevec *lru_pvec)
1872 int err;
1873 struct page *page;
1874 repeat:
1875 page = find_lock_page(mapping, index);
1876 if (!page) {
1877 if (!*cached_page) {
1878 *cached_page = page_cache_alloc(mapping);
1879 if (!*cached_page)
1880 return NULL;
1882 err = add_to_page_cache(*cached_page, mapping,
1883 index, GFP_KERNEL);
1884 if (err == -EEXIST)
1885 goto repeat;
1886 if (err == 0) {
1887 page = *cached_page;
1888 page_cache_get(page);
1889 if (!pagevec_add(lru_pvec, page))
1890 __pagevec_lru_add(lru_pvec);
1891 *cached_page = NULL;
1894 return page;
1897 /*
1898 * The logic we want is
1900 * if suid or (sgid and xgrp)
1901 * remove privs
1902 */
1903 int remove_suid(struct dentry *dentry)
1905 mode_t mode = dentry->d_inode->i_mode;
1906 int kill = 0;
1907 int result = 0;
1909 /* suid always must be killed */
1910 if (unlikely(mode & S_ISUID))
1911 kill = ATTR_KILL_SUID;
1913 /*
1914 * sgid without any exec bits is just a mandatory locking mark; leave
1915 * it alone. If some exec bits are set, it's a real sgid; kill it.
1916 */
1917 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1918 kill |= ATTR_KILL_SGID;
1920 if (unlikely(kill && !capable(CAP_FSETID))) {
1921 struct iattr newattrs;
1923 newattrs.ia_valid = ATTR_FORCE | kill;
1924 result = notify_change(dentry, &newattrs);
1926 return result;
1928 EXPORT_SYMBOL(remove_suid);
1930 size_t
1931 __filemap_copy_from_user_iovec_inatomic(char *vaddr,
1932 const struct iovec *iov, size_t base, size_t bytes)
1934 size_t copied = 0, left = 0;
1936 while (bytes) {
1937 char __user *buf = iov->iov_base + base;
1938 int copy = min(bytes, iov->iov_len - base);
1940 base = 0;
1941 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
1942 copied += copy;
1943 bytes -= copy;
1944 vaddr += copy;
1945 iov++;
1947 if (unlikely(left))
1948 break;
1950 return copied - left;
1953 /*
1954 * Performs necessary checks before doing a write
1956 * Can adjust writing position or amount of bytes to write.
1957 * Returns appropriate error code that caller should return or
1958 * zero in case that write should be allowed.
1959 */
1960 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1962 struct inode *inode = file->f_mapping->host;
1963 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1965 if (unlikely(*pos < 0))
1966 return -EINVAL;
1968 if (!isblk) {
1969 /* FIXME: this is for backwards compatibility with 2.4 */
1970 if (file->f_flags & O_APPEND)
1971 *pos = i_size_read(inode);
1973 if (limit != RLIM_INFINITY) {
1974 if (*pos >= limit) {
1975 send_sig(SIGXFSZ, current, 0);
1976 return -EFBIG;
1978 if (*count > limit - (typeof(limit))*pos) {
1979 *count = limit - (typeof(limit))*pos;
1984 /*
1985 * LFS rule
1986 */
1987 if (unlikely(*pos + *count > MAX_NON_LFS &&
1988 !(file->f_flags & O_LARGEFILE))) {
1989 if (*pos >= MAX_NON_LFS) {
1990 send_sig(SIGXFSZ, current, 0);
1991 return -EFBIG;
1993 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1994 *count = MAX_NON_LFS - (unsigned long)*pos;
1998 /*
1999 * Are we about to exceed the fs block limit ?
2001 * If we have written data it becomes a short write. If we have
2002 * exceeded without writing data we send a signal and return EFBIG.
2003 * Linus frestrict idea will clean these up nicely..
2004 */
2005 if (likely(!isblk)) {
2006 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2007 if (*count || *pos > inode->i_sb->s_maxbytes) {
2008 send_sig(SIGXFSZ, current, 0);
2009 return -EFBIG;
2011 /* zero-length writes at ->s_maxbytes are OK */
2014 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2015 *count = inode->i_sb->s_maxbytes - *pos;
2016 } else {
2017 loff_t isize;
2018 if (bdev_read_only(I_BDEV(inode)))
2019 return -EPERM;
2020 isize = i_size_read(inode);
2021 if (*pos >= isize) {
2022 if (*count || *pos > isize)
2023 return -ENOSPC;
2026 if (*pos + *count > isize)
2027 *count = isize - *pos;
2029 return 0;
2031 EXPORT_SYMBOL(generic_write_checks);
2033 ssize_t
2034 generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2035 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2036 size_t count, size_t ocount)
2038 struct file *file = iocb->ki_filp;
2039 struct address_space *mapping = file->f_mapping;
2040 struct inode *inode = mapping->host;
2041 ssize_t written;
2043 if (count != ocount)
2044 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2046 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2047 if (written > 0) {
2048 loff_t end = pos + written;
2049 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2050 i_size_write(inode, end);
2051 mark_inode_dirty(inode);
2053 *ppos = end;
2056 /*
2057 * Sync the fs metadata but not the minor inode changes and
2058 * of course not the data as we did direct DMA for the IO.
2059 * i_mutex is held, which protects generic_osync_inode() from
2060 * livelocking.
2061 */
2062 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2063 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2064 if (err < 0)
2065 written = err;
2067 if (written == count && !is_sync_kiocb(iocb))
2068 written = -EIOCBQUEUED;
2069 return written;
2071 EXPORT_SYMBOL(generic_file_direct_write);
2073 ssize_t
2074 generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2075 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2076 size_t count, ssize_t written)
2078 struct file *file = iocb->ki_filp;
2079 struct address_space * mapping = file->f_mapping;
2080 const struct address_space_operations *a_ops = mapping->a_ops;
2081 struct inode *inode = mapping->host;
2082 long status = 0;
2083 struct page *page;
2084 struct page *cached_page = NULL;
2085 size_t bytes;
2086 struct pagevec lru_pvec;
2087 const struct iovec *cur_iov = iov; /* current iovec */
2088 size_t iov_base = 0; /* offset in the current iovec */
2089 char __user *buf;
2091 pagevec_init(&lru_pvec, 0);
2093 /*
2094 * handle partial DIO write. Adjust cur_iov if needed.
2095 */
2096 if (likely(nr_segs == 1))
2097 buf = iov->iov_base + written;
2098 else {
2099 filemap_set_next_iovec(&cur_iov, &iov_base, written);
2100 buf = cur_iov->iov_base + iov_base;
2103 do {
2104 unsigned long index;
2105 unsigned long offset;
2106 size_t copied;
2108 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2109 index = pos >> PAGE_CACHE_SHIFT;
2110 bytes = PAGE_CACHE_SIZE - offset;
2112 /* Limit the size of the copy to the caller's write size */
2113 bytes = min(bytes, count);
2115 /*
2116 * Limit the size of the copy to that of the current segment,
2117 * because fault_in_pages_readable() doesn't know how to walk
2118 * segments.
2119 */
2120 bytes = min(bytes, cur_iov->iov_len - iov_base);
2122 /*
2123 * Bring in the user page that we will copy from _first_.
2124 * Otherwise there's a nasty deadlock on copying from the
2125 * same page as we're writing to, without it being marked
2126 * up-to-date.
2127 */
2128 fault_in_pages_readable(buf, bytes);
2130 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2131 if (!page) {
2132 status = -ENOMEM;
2133 break;
2136 if (unlikely(bytes == 0)) {
2137 status = 0;
2138 copied = 0;
2139 goto zero_length_segment;
2142 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2143 if (unlikely(status)) {
2144 loff_t isize = i_size_read(inode);
2146 if (status != AOP_TRUNCATED_PAGE)
2147 unlock_page(page);
2148 page_cache_release(page);
2149 if (status == AOP_TRUNCATED_PAGE)
2150 continue;
2151 /*
2152 * prepare_write() may have instantiated a few blocks
2153 * outside i_size. Trim these off again.
2154 */
2155 if (pos + bytes > isize)
2156 vmtruncate(inode, isize);
2157 break;
2159 if (likely(nr_segs == 1))
2160 copied = filemap_copy_from_user(page, offset,
2161 buf, bytes);
2162 else
2163 copied = filemap_copy_from_user_iovec(page, offset,
2164 cur_iov, iov_base, bytes);
2165 flush_dcache_page(page);
2166 status = a_ops->commit_write(file, page, offset, offset+bytes);
2167 if (status == AOP_TRUNCATED_PAGE) {
2168 page_cache_release(page);
2169 continue;
2171 zero_length_segment:
2172 if (likely(copied >= 0)) {
2173 if (!status)
2174 status = copied;
2176 if (status >= 0) {
2177 written += status;
2178 count -= status;
2179 pos += status;
2180 buf += status;
2181 if (unlikely(nr_segs > 1)) {
2182 filemap_set_next_iovec(&cur_iov,
2183 &iov_base, status);
2184 if (count)
2185 buf = cur_iov->iov_base +
2186 iov_base;
2187 } else {
2188 iov_base += status;
2192 if (unlikely(copied != bytes))
2193 if (status >= 0)
2194 status = -EFAULT;
2195 unlock_page(page);
2196 mark_page_accessed(page);
2197 page_cache_release(page);
2198 if (status < 0)
2199 break;
2200 balance_dirty_pages_ratelimited(mapping);
2201 cond_resched();
2202 } while (count);
2203 *ppos = pos;
2205 if (cached_page)
2206 page_cache_release(cached_page);
2208 /*
2209 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2210 */
2211 if (likely(status >= 0)) {
2212 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2213 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2214 status = generic_osync_inode(inode, mapping,
2215 OSYNC_METADATA|OSYNC_DATA);
2219 /*
2220 * If we get here for O_DIRECT writes then we must have fallen through
2221 * to buffered writes (block instantiation inside i_size). So we sync
2222 * the file data here, to try to honour O_DIRECT expectations.
2223 */
2224 if (unlikely(file->f_flags & O_DIRECT) && written)
2225 status = filemap_write_and_wait(mapping);
2227 pagevec_lru_add(&lru_pvec);
2228 return written ? written : status;
2230 EXPORT_SYMBOL(generic_file_buffered_write);
2232 static ssize_t
2233 __generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2234 unsigned long nr_segs, loff_t *ppos)
2236 struct file *file = iocb->ki_filp;
2237 const struct address_space * mapping = file->f_mapping;
2238 size_t ocount; /* original count */
2239 size_t count; /* after file limit checks */
2240 struct inode *inode = mapping->host;
2241 unsigned long seg;
2242 loff_t pos;
2243 ssize_t written;
2244 ssize_t err;
2246 ocount = 0;
2247 for (seg = 0; seg < nr_segs; seg++) {
2248 const struct iovec *iv = &iov[seg];
2250 /*
2251 * If any segment has a negative length, or the cumulative
2252 * length ever wraps negative then return -EINVAL.
2253 */
2254 ocount += iv->iov_len;
2255 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2256 return -EINVAL;
2257 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2258 continue;
2259 if (seg == 0)
2260 return -EFAULT;
2261 nr_segs = seg;
2262 ocount -= iv->iov_len; /* This segment is no good */
2263 break;
2266 count = ocount;
2267 pos = *ppos;
2269 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2271 /* We can write back this queue in page reclaim */
2272 current->backing_dev_info = mapping->backing_dev_info;
2273 written = 0;
2275 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2276 if (err)
2277 goto out;
2279 if (count == 0)
2280 goto out;
2282 err = remove_suid(file->f_dentry);
2283 if (err)
2284 goto out;
2286 file_update_time(file);
2288 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2289 if (unlikely(file->f_flags & O_DIRECT)) {
2290 written = generic_file_direct_write(iocb, iov,
2291 &nr_segs, pos, ppos, count, ocount);
2292 if (written < 0 || written == count)
2293 goto out;
2294 /*
2295 * direct-io write to a hole: fall through to buffered I/O
2296 * for completing the rest of the request.
2297 */
2298 pos += written;
2299 count -= written;
2302 written = generic_file_buffered_write(iocb, iov, nr_segs,
2303 pos, ppos, count, written);
2304 out:
2305 current->backing_dev_info = NULL;
2306 return written ? written : err;
2308 EXPORT_SYMBOL(generic_file_aio_write_nolock);
2310 ssize_t
2311 generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2312 unsigned long nr_segs, loff_t *ppos)
2314 struct file *file = iocb->ki_filp;
2315 struct address_space *mapping = file->f_mapping;
2316 struct inode *inode = mapping->host;
2317 ssize_t ret;
2318 loff_t pos = *ppos;
2320 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2322 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2323 int err;
2325 err = sync_page_range_nolock(inode, mapping, pos, ret);
2326 if (err < 0)
2327 ret = err;
2329 return ret;
2332 static ssize_t
2333 __generic_file_write_nolock(struct file *file, const struct iovec *iov,
2334 unsigned long nr_segs, loff_t *ppos)
2336 struct kiocb kiocb;
2337 ssize_t ret;
2339 init_sync_kiocb(&kiocb, file);
2340 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2341 if (ret == -EIOCBQUEUED)
2342 ret = wait_on_sync_kiocb(&kiocb);
2343 return ret;
2346 ssize_t
2347 generic_file_write_nolock(struct file *file, const struct iovec *iov,
2348 unsigned long nr_segs, loff_t *ppos)
2350 struct kiocb kiocb;
2351 ssize_t ret;
2353 init_sync_kiocb(&kiocb, file);
2354 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2355 if (-EIOCBQUEUED == ret)
2356 ret = wait_on_sync_kiocb(&kiocb);
2357 return ret;
2359 EXPORT_SYMBOL(generic_file_write_nolock);
2361 ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2362 size_t count, loff_t pos)
2364 struct file *file = iocb->ki_filp;
2365 struct address_space *mapping = file->f_mapping;
2366 struct inode *inode = mapping->host;
2367 ssize_t ret;
2368 struct iovec local_iov = { .iov_base = (void __user *)buf,
2369 .iov_len = count };
2371 BUG_ON(iocb->ki_pos != pos);
2373 mutex_lock(&inode->i_mutex);
2374 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2375 &iocb->ki_pos);
2376 mutex_unlock(&inode->i_mutex);
2378 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2379 ssize_t err;
2381 err = sync_page_range(inode, mapping, pos, ret);
2382 if (err < 0)
2383 ret = err;
2385 return ret;
2387 EXPORT_SYMBOL(generic_file_aio_write);
2389 ssize_t generic_file_write(struct file *file, const char __user *buf,
2390 size_t count, loff_t *ppos)
2392 struct address_space *mapping = file->f_mapping;
2393 struct inode *inode = mapping->host;
2394 ssize_t ret;
2395 struct iovec local_iov = { .iov_base = (void __user *)buf,
2396 .iov_len = count };
2398 mutex_lock(&inode->i_mutex);
2399 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2400 mutex_unlock(&inode->i_mutex);
2402 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2403 ssize_t err;
2405 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2406 if (err < 0)
2407 ret = err;
2409 return ret;
2411 EXPORT_SYMBOL(generic_file_write);
2413 ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2414 unsigned long nr_segs, loff_t *ppos)
2416 struct kiocb kiocb;
2417 ssize_t ret;
2419 init_sync_kiocb(&kiocb, filp);
2420 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2421 if (-EIOCBQUEUED == ret)
2422 ret = wait_on_sync_kiocb(&kiocb);
2423 return ret;
2425 EXPORT_SYMBOL(generic_file_readv);
2427 ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2428 unsigned long nr_segs, loff_t *ppos)
2430 struct address_space *mapping = file->f_mapping;
2431 struct inode *inode = mapping->host;
2432 ssize_t ret;
2434 mutex_lock(&inode->i_mutex);
2435 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2436 mutex_unlock(&inode->i_mutex);
2438 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2439 int err;
2441 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2442 if (err < 0)
2443 ret = err;
2445 return ret;
2447 EXPORT_SYMBOL(generic_file_writev);
2449 /*
2450 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
2451 * went wrong during pagecache shootdown.
2452 */
2453 static ssize_t
2454 generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2455 loff_t offset, unsigned long nr_segs)
2457 struct file *file = iocb->ki_filp;
2458 struct address_space *mapping = file->f_mapping;
2459 ssize_t retval;
2460 size_t write_len = 0;
2462 /*
2463 * If it's a write, unmap all mmappings of the file up-front. This
2464 * will cause any pte dirty bits to be propagated into the pageframes
2465 * for the subsequent filemap_write_and_wait().
2466 */
2467 if (rw == WRITE) {
2468 write_len = iov_length(iov, nr_segs);
2469 if (mapping_mapped(mapping))
2470 unmap_mapping_range(mapping, offset, write_len, 0);
2473 retval = filemap_write_and_wait(mapping);
2474 if (retval == 0) {
2475 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2476 offset, nr_segs);
2477 if (rw == WRITE && mapping->nrpages) {
2478 pgoff_t end = (offset + write_len - 1)
2479 >> PAGE_CACHE_SHIFT;
2480 int err = invalidate_inode_pages2_range(mapping,
2481 offset >> PAGE_CACHE_SHIFT, end);
2482 if (err)
2483 retval = err;
2486 return retval;