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CommitLineData
1da177e4
LT
1/*
2 * linux/mm/filemap.c
3 *
4 * Copyright (C) 1994-1999 Linus Torvalds
5 */
6
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 */
1da177e4
LT
12#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/compiler.h>
15#include <linux/fs.h>
c22ce143 16#include <linux/uaccess.h>
1da177e4 17#include <linux/aio.h>
c59ede7b 18#include <linux/capability.h>
1da177e4
LT
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>
53253383 28#include <linux/backing-dev.h>
1da177e4
LT
29#include <linux/pagevec.h>
30#include <linux/blkdev.h>
31#include <linux/security.h>
32#include <linux/syscalls.h>
44110fe3 33#include <linux/cpuset.h>
2f718ffc 34#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
8a9f3ccd 35#include <linux/memcontrol.h>
0f8053a5
NP
36#include "internal.h"
37
1da177e4 38/*
1da177e4
LT
39 * FIXME: remove all knowledge of the buffer layer from the core VM
40 */
41#include <linux/buffer_head.h> /* for generic_osync_inode */
42
1da177e4
LT
43#include <asm/mman.h>
44
5ce7852c
AB
45static ssize_t
46generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
47 loff_t offset, unsigned long nr_segs);
48
1da177e4
LT
49/*
50 * Shared mappings implemented 30.11.1994. It's not fully working yet,
51 * though.
52 *
53 * Shared mappings now work. 15.8.1995 Bruno.
54 *
55 * finished 'unifying' the page and buffer cache and SMP-threaded the
56 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
57 *
58 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
59 */
60
61/*
62 * Lock ordering:
63 *
64 * ->i_mmap_lock (vmtruncate)
65 * ->private_lock (__free_pte->__set_page_dirty_buffers)
5d337b91
HD
66 * ->swap_lock (exclusive_swap_page, others)
67 * ->mapping->tree_lock
1da177e4 68 *
1b1dcc1b 69 * ->i_mutex
1da177e4
LT
70 * ->i_mmap_lock (truncate->unmap_mapping_range)
71 *
72 * ->mmap_sem
73 * ->i_mmap_lock
b8072f09 74 * ->page_table_lock or pte_lock (various, mainly in memory.c)
1da177e4
LT
75 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
76 *
77 * ->mmap_sem
78 * ->lock_page (access_process_vm)
79 *
82591e6e
NP
80 * ->i_mutex (generic_file_buffered_write)
81 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
1da177e4 82 *
1b1dcc1b 83 * ->i_mutex
1da177e4
LT
84 * ->i_alloc_sem (various)
85 *
86 * ->inode_lock
87 * ->sb_lock (fs/fs-writeback.c)
88 * ->mapping->tree_lock (__sync_single_inode)
89 *
90 * ->i_mmap_lock
91 * ->anon_vma.lock (vma_adjust)
92 *
93 * ->anon_vma.lock
b8072f09 94 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
1da177e4 95 *
b8072f09 96 * ->page_table_lock or pte_lock
5d337b91 97 * ->swap_lock (try_to_unmap_one)
1da177e4
LT
98 * ->private_lock (try_to_unmap_one)
99 * ->tree_lock (try_to_unmap_one)
100 * ->zone.lru_lock (follow_page->mark_page_accessed)
053837fc 101 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
1da177e4
LT
102 * ->private_lock (page_remove_rmap->set_page_dirty)
103 * ->tree_lock (page_remove_rmap->set_page_dirty)
104 * ->inode_lock (page_remove_rmap->set_page_dirty)
105 * ->inode_lock (zap_pte_range->set_page_dirty)
106 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
107 *
108 * ->task->proc_lock
109 * ->dcache_lock (proc_pid_lookup)
110 */
111
112/*
113 * Remove a page from the page cache and free it. Caller has to make
114 * sure the page is locked and that nobody else uses it - or that usage
115 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
116 */
117void __remove_from_page_cache(struct page *page)
118{
119 struct address_space *mapping = page->mapping;
120
8a9f3ccd 121 mem_cgroup_uncharge_page(page);
1da177e4
LT
122 radix_tree_delete(&mapping->page_tree, page->index);
123 page->mapping = NULL;
124 mapping->nrpages--;
347ce434 125 __dec_zone_page_state(page, NR_FILE_PAGES);
45426812 126 BUG_ON(page_mapped(page));
3a692790
LT
127
128 /*
129 * Some filesystems seem to re-dirty the page even after
130 * the VM has canceled the dirty bit (eg ext3 journaling).
131 *
132 * Fix it up by doing a final dirty accounting check after
133 * having removed the page entirely.
134 */
135 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
136 dec_zone_page_state(page, NR_FILE_DIRTY);
137 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
138 }
1da177e4
LT
139}
140
141void remove_from_page_cache(struct page *page)
142{
143 struct address_space *mapping = page->mapping;
144
cd7619d6 145 BUG_ON(!PageLocked(page));
1da177e4
LT
146
147 write_lock_irq(&mapping->tree_lock);
148 __remove_from_page_cache(page);
149 write_unlock_irq(&mapping->tree_lock);
150}
151
152static int sync_page(void *word)
153{
154 struct address_space *mapping;
155 struct page *page;
156
07808b74 157 page = container_of((unsigned long *)word, struct page, flags);
1da177e4
LT
158
159 /*
dd1d5afc
WLII
160 * page_mapping() is being called without PG_locked held.
161 * Some knowledge of the state and use of the page is used to
162 * reduce the requirements down to a memory barrier.
163 * The danger here is of a stale page_mapping() return value
164 * indicating a struct address_space different from the one it's
165 * associated with when it is associated with one.
166 * After smp_mb(), it's either the correct page_mapping() for
167 * the page, or an old page_mapping() and the page's own
168 * page_mapping() has gone NULL.
169 * The ->sync_page() address_space operation must tolerate
170 * page_mapping() going NULL. By an amazing coincidence,
171 * this comes about because none of the users of the page
172 * in the ->sync_page() methods make essential use of the
173 * page_mapping(), merely passing the page down to the backing
174 * device's unplug functions when it's non-NULL, which in turn
4c21e2f2 175 * ignore it for all cases but swap, where only page_private(page) is
dd1d5afc
WLII
176 * of interest. When page_mapping() does go NULL, the entire
177 * call stack gracefully ignores the page and returns.
178 * -- wli
1da177e4
LT
179 */
180 smp_mb();
181 mapping = page_mapping(page);
182 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
183 mapping->a_ops->sync_page(page);
184 io_schedule();
185 return 0;
186}
187
2687a356
MW
188static int sync_page_killable(void *word)
189{
190 sync_page(word);
191 return fatal_signal_pending(current) ? -EINTR : 0;
192}
193
1da177e4 194/**
485bb99b 195 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
67be2dd1
MW
196 * @mapping: address space structure to write
197 * @start: offset in bytes where the range starts
469eb4d0 198 * @end: offset in bytes where the range ends (inclusive)
67be2dd1 199 * @sync_mode: enable synchronous operation
1da177e4 200 *
485bb99b
RD
201 * Start writeback against all of a mapping's dirty pages that lie
202 * within the byte offsets <start, end> inclusive.
203 *
1da177e4 204 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
485bb99b 205 * opposed to a regular memory cleansing writeback. The difference between
1da177e4
LT
206 * these two operations is that if a dirty page/buffer is encountered, it must
207 * be waited upon, and not just skipped over.
208 */
ebcf28e1
AM
209int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
210 loff_t end, int sync_mode)
1da177e4
LT
211{
212 int ret;
213 struct writeback_control wbc = {
214 .sync_mode = sync_mode,
215 .nr_to_write = mapping->nrpages * 2,
111ebb6e
OH
216 .range_start = start,
217 .range_end = end,
1da177e4
LT
218 };
219
220 if (!mapping_cap_writeback_dirty(mapping))
221 return 0;
222
223 ret = do_writepages(mapping, &wbc);
224 return ret;
225}
226
227static inline int __filemap_fdatawrite(struct address_space *mapping,
228 int sync_mode)
229{
111ebb6e 230 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
1da177e4
LT
231}
232
233int filemap_fdatawrite(struct address_space *mapping)
234{
235 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
236}
237EXPORT_SYMBOL(filemap_fdatawrite);
238
ebcf28e1
AM
239static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
240 loff_t end)
1da177e4
LT
241{
242 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
243}
244
485bb99b
RD
245/**
246 * filemap_flush - mostly a non-blocking flush
247 * @mapping: target address_space
248 *
1da177e4
LT
249 * This is a mostly non-blocking flush. Not suitable for data-integrity
250 * purposes - I/O may not be started against all dirty pages.
251 */
252int filemap_flush(struct address_space *mapping)
253{
254 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
255}
256EXPORT_SYMBOL(filemap_flush);
257
485bb99b
RD
258/**
259 * wait_on_page_writeback_range - wait for writeback to complete
260 * @mapping: target address_space
261 * @start: beginning page index
262 * @end: ending page index
263 *
1da177e4
LT
264 * Wait for writeback to complete against pages indexed by start->end
265 * inclusive
266 */
ebcf28e1 267int wait_on_page_writeback_range(struct address_space *mapping,
1da177e4
LT
268 pgoff_t start, pgoff_t end)
269{
270 struct pagevec pvec;
271 int nr_pages;
272 int ret = 0;
273 pgoff_t index;
274
275 if (end < start)
276 return 0;
277
278 pagevec_init(&pvec, 0);
279 index = start;
280 while ((index <= end) &&
281 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
282 PAGECACHE_TAG_WRITEBACK,
283 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
284 unsigned i;
285
286 for (i = 0; i < nr_pages; i++) {
287 struct page *page = pvec.pages[i];
288
289 /* until radix tree lookup accepts end_index */
290 if (page->index > end)
291 continue;
292
293 wait_on_page_writeback(page);
294 if (PageError(page))
295 ret = -EIO;
296 }
297 pagevec_release(&pvec);
298 cond_resched();
299 }
300
301 /* Check for outstanding write errors */
302 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
303 ret = -ENOSPC;
304 if (test_and_clear_bit(AS_EIO, &mapping->flags))
305 ret = -EIO;
306
307 return ret;
308}
309
485bb99b
RD
310/**
311 * sync_page_range - write and wait on all pages in the passed range
312 * @inode: target inode
313 * @mapping: target address_space
314 * @pos: beginning offset in pages to write
315 * @count: number of bytes to write
316 *
1da177e4
LT
317 * Write and wait upon all the pages in the passed range. This is a "data
318 * integrity" operation. It waits upon in-flight writeout before starting and
319 * waiting upon new writeout. If there was an IO error, return it.
320 *
1b1dcc1b 321 * We need to re-take i_mutex during the generic_osync_inode list walk because
1da177e4
LT
322 * it is otherwise livelockable.
323 */
324int sync_page_range(struct inode *inode, struct address_space *mapping,
268fc16e 325 loff_t pos, loff_t count)
1da177e4
LT
326{
327 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
328 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
329 int ret;
330
331 if (!mapping_cap_writeback_dirty(mapping) || !count)
332 return 0;
333 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
334 if (ret == 0) {
1b1dcc1b 335 mutex_lock(&inode->i_mutex);
1da177e4 336 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1b1dcc1b 337 mutex_unlock(&inode->i_mutex);
1da177e4
LT
338 }
339 if (ret == 0)
340 ret = wait_on_page_writeback_range(mapping, start, end);
341 return ret;
342}
343EXPORT_SYMBOL(sync_page_range);
344
485bb99b 345/**
7682486b 346 * sync_page_range_nolock - write & wait on all pages in the passed range without locking
485bb99b
RD
347 * @inode: target inode
348 * @mapping: target address_space
349 * @pos: beginning offset in pages to write
350 * @count: number of bytes to write
351 *
72fd4a35 352 * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
1da177e4
LT
353 * as it forces O_SYNC writers to different parts of the same file
354 * to be serialised right until io completion.
355 */
268fc16e
OH
356int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
357 loff_t pos, loff_t count)
1da177e4
LT
358{
359 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
360 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
361 int ret;
362
363 if (!mapping_cap_writeback_dirty(mapping) || !count)
364 return 0;
365 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
366 if (ret == 0)
367 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
368 if (ret == 0)
369 ret = wait_on_page_writeback_range(mapping, start, end);
370 return ret;
371}
268fc16e 372EXPORT_SYMBOL(sync_page_range_nolock);
1da177e4
LT
373
374/**
485bb99b 375 * filemap_fdatawait - wait for all under-writeback pages to complete
1da177e4 376 * @mapping: address space structure to wait for
485bb99b
RD
377 *
378 * Walk the list of under-writeback pages of the given address space
379 * and wait for all of them.
1da177e4
LT
380 */
381int filemap_fdatawait(struct address_space *mapping)
382{
383 loff_t i_size = i_size_read(mapping->host);
384
385 if (i_size == 0)
386 return 0;
387
388 return wait_on_page_writeback_range(mapping, 0,
389 (i_size - 1) >> PAGE_CACHE_SHIFT);
390}
391EXPORT_SYMBOL(filemap_fdatawait);
392
393int filemap_write_and_wait(struct address_space *mapping)
394{
28fd1298 395 int err = 0;
1da177e4
LT
396
397 if (mapping->nrpages) {
28fd1298
OH
398 err = filemap_fdatawrite(mapping);
399 /*
400 * Even if the above returned error, the pages may be
401 * written partially (e.g. -ENOSPC), so we wait for it.
402 * But the -EIO is special case, it may indicate the worst
403 * thing (e.g. bug) happened, so we avoid waiting for it.
404 */
405 if (err != -EIO) {
406 int err2 = filemap_fdatawait(mapping);
407 if (!err)
408 err = err2;
409 }
1da177e4 410 }
28fd1298 411 return err;
1da177e4 412}
28fd1298 413EXPORT_SYMBOL(filemap_write_and_wait);
1da177e4 414
485bb99b
RD
415/**
416 * filemap_write_and_wait_range - write out & wait on a file range
417 * @mapping: the address_space for the pages
418 * @lstart: offset in bytes where the range starts
419 * @lend: offset in bytes where the range ends (inclusive)
420 *
469eb4d0
AM
421 * Write out and wait upon file offsets lstart->lend, inclusive.
422 *
423 * Note that `lend' is inclusive (describes the last byte to be written) so
424 * that this function can be used to write to the very end-of-file (end = -1).
425 */
1da177e4
LT
426int filemap_write_and_wait_range(struct address_space *mapping,
427 loff_t lstart, loff_t lend)
428{
28fd1298 429 int err = 0;
1da177e4
LT
430
431 if (mapping->nrpages) {
28fd1298
OH
432 err = __filemap_fdatawrite_range(mapping, lstart, lend,
433 WB_SYNC_ALL);
434 /* See comment of filemap_write_and_wait() */
435 if (err != -EIO) {
436 int err2 = wait_on_page_writeback_range(mapping,
437 lstart >> PAGE_CACHE_SHIFT,
438 lend >> PAGE_CACHE_SHIFT);
439 if (!err)
440 err = err2;
441 }
1da177e4 442 }
28fd1298 443 return err;
1da177e4
LT
444}
445
485bb99b
RD
446/**
447 * add_to_page_cache - add newly allocated pagecache pages
448 * @page: page to add
449 * @mapping: the page's address_space
450 * @offset: page index
451 * @gfp_mask: page allocation mode
452 *
453 * This function is used to add newly allocated pagecache pages;
1da177e4
LT
454 * the page is new, so we can just run SetPageLocked() against it.
455 * The other page state flags were set by rmqueue().
456 *
457 * This function does not add the page to the LRU. The caller must do that.
458 */
459int add_to_page_cache(struct page *page, struct address_space *mapping,
6daa0e28 460 pgoff_t offset, gfp_t gfp_mask)
1da177e4 461{
4c6bc8dd
BP
462 int error = mem_cgroup_cache_charge(page, current->mm,
463 gfp_mask & ~__GFP_HIGHMEM);
35c754d7
BS
464 if (error)
465 goto out;
1da177e4 466
35c754d7 467 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
1da177e4
LT
468 if (error == 0) {
469 write_lock_irq(&mapping->tree_lock);
470 error = radix_tree_insert(&mapping->page_tree, offset, page);
471 if (!error) {
472 page_cache_get(page);
473 SetPageLocked(page);
474 page->mapping = mapping;
475 page->index = offset;
476 mapping->nrpages++;
347ce434 477 __inc_zone_page_state(page, NR_FILE_PAGES);
8a9f3ccd
BS
478 } else
479 mem_cgroup_uncharge_page(page);
480
1da177e4
LT
481 write_unlock_irq(&mapping->tree_lock);
482 radix_tree_preload_end();
35c754d7
BS
483 } else
484 mem_cgroup_uncharge_page(page);
8a9f3ccd 485out:
1da177e4
LT
486 return error;
487}
1da177e4
LT
488EXPORT_SYMBOL(add_to_page_cache);
489
490int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
6daa0e28 491 pgoff_t offset, gfp_t gfp_mask)
1da177e4
LT
492{
493 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
494 if (ret == 0)
495 lru_cache_add(page);
496 return ret;
497}
498
44110fe3 499#ifdef CONFIG_NUMA
2ae88149 500struct page *__page_cache_alloc(gfp_t gfp)
44110fe3
PJ
501{
502 if (cpuset_do_page_mem_spread()) {
503 int n = cpuset_mem_spread_node();
2ae88149 504 return alloc_pages_node(n, gfp, 0);
44110fe3 505 }
2ae88149 506 return alloc_pages(gfp, 0);
44110fe3 507}
2ae88149 508EXPORT_SYMBOL(__page_cache_alloc);
44110fe3
PJ
509#endif
510
db37648c
NP
511static int __sleep_on_page_lock(void *word)
512{
513 io_schedule();
514 return 0;
515}
516
1da177e4
LT
517/*
518 * In order to wait for pages to become available there must be
519 * waitqueues associated with pages. By using a hash table of
520 * waitqueues where the bucket discipline is to maintain all
521 * waiters on the same queue and wake all when any of the pages
522 * become available, and for the woken contexts to check to be
523 * sure the appropriate page became available, this saves space
524 * at a cost of "thundering herd" phenomena during rare hash
525 * collisions.
526 */
527static wait_queue_head_t *page_waitqueue(struct page *page)
528{
529 const struct zone *zone = page_zone(page);
530
531 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
532}
533
534static inline void wake_up_page(struct page *page, int bit)
535{
536 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
537}
538
920c7a5d 539void wait_on_page_bit(struct page *page, int bit_nr)
1da177e4
LT
540{
541 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
542
543 if (test_bit(bit_nr, &page->flags))
544 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
545 TASK_UNINTERRUPTIBLE);
546}
547EXPORT_SYMBOL(wait_on_page_bit);
548
549/**
485bb99b 550 * unlock_page - unlock a locked page
1da177e4
LT
551 * @page: the page
552 *
553 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
554 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
555 * mechananism between PageLocked pages and PageWriteback pages is shared.
556 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
557 *
558 * The first mb is necessary to safely close the critical section opened by the
559 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
560 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
561 * parallel wait_on_page_locked()).
562 */
920c7a5d 563void unlock_page(struct page *page)
1da177e4
LT
564{
565 smp_mb__before_clear_bit();
566 if (!TestClearPageLocked(page))
567 BUG();
568 smp_mb__after_clear_bit();
569 wake_up_page(page, PG_locked);
570}
571EXPORT_SYMBOL(unlock_page);
572
485bb99b
RD
573/**
574 * end_page_writeback - end writeback against a page
575 * @page: the page
1da177e4
LT
576 */
577void end_page_writeback(struct page *page)
578{
579 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
580 if (!test_clear_page_writeback(page))
581 BUG();
582 }
583 smp_mb__after_clear_bit();
584 wake_up_page(page, PG_writeback);
585}
586EXPORT_SYMBOL(end_page_writeback);
587
485bb99b
RD
588/**
589 * __lock_page - get a lock on the page, assuming we need to sleep to get it
590 * @page: the page to lock
1da177e4 591 *
485bb99b 592 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
1da177e4
LT
593 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
594 * chances are that on the second loop, the block layer's plug list is empty,
595 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
596 */
920c7a5d 597void __lock_page(struct page *page)
1da177e4
LT
598{
599 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
600
601 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
602 TASK_UNINTERRUPTIBLE);
603}
604EXPORT_SYMBOL(__lock_page);
605
b5606c2d 606int __lock_page_killable(struct page *page)
2687a356
MW
607{
608 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
609
610 return __wait_on_bit_lock(page_waitqueue(page), &wait,
611 sync_page_killable, TASK_KILLABLE);
612}
613
7682486b
RD
614/**
615 * __lock_page_nosync - get a lock on the page, without calling sync_page()
616 * @page: the page to lock
617 *
db37648c
NP
618 * Variant of lock_page that does not require the caller to hold a reference
619 * on the page's mapping.
620 */
920c7a5d 621void __lock_page_nosync(struct page *page)
db37648c
NP
622{
623 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
624 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
625 TASK_UNINTERRUPTIBLE);
626}
627
485bb99b
RD
628/**
629 * find_get_page - find and get a page reference
630 * @mapping: the address_space to search
631 * @offset: the page index
632 *
da6052f7
NP
633 * Is there a pagecache struct page at the given (mapping, offset) tuple?
634 * If yes, increment its refcount and return it; if no, return NULL.
1da177e4 635 */
57f6b96c 636struct page * find_get_page(struct address_space *mapping, pgoff_t offset)
1da177e4
LT
637{
638 struct page *page;
639
640 read_lock_irq(&mapping->tree_lock);
641 page = radix_tree_lookup(&mapping->page_tree, offset);
642 if (page)
643 page_cache_get(page);
644 read_unlock_irq(&mapping->tree_lock);
645 return page;
646}
1da177e4
LT
647EXPORT_SYMBOL(find_get_page);
648
1da177e4
LT
649/**
650 * find_lock_page - locate, pin and lock a pagecache page
67be2dd1
MW
651 * @mapping: the address_space to search
652 * @offset: the page index
1da177e4
LT
653 *
654 * Locates the desired pagecache page, locks it, increments its reference
655 * count and returns its address.
656 *
657 * Returns zero if the page was not present. find_lock_page() may sleep.
658 */
659struct page *find_lock_page(struct address_space *mapping,
57f6b96c 660 pgoff_t offset)
1da177e4
LT
661{
662 struct page *page;
663
1da177e4 664repeat:
45726cb4 665 read_lock_irq(&mapping->tree_lock);
1da177e4
LT
666 page = radix_tree_lookup(&mapping->page_tree, offset);
667 if (page) {
668 page_cache_get(page);
669 if (TestSetPageLocked(page)) {
670 read_unlock_irq(&mapping->tree_lock);
bbfbb7ce 671 __lock_page(page);
1da177e4
LT
672
673 /* Has the page been truncated while we slept? */
45726cb4 674 if (unlikely(page->mapping != mapping)) {
1da177e4
LT
675 unlock_page(page);
676 page_cache_release(page);
677 goto repeat;
678 }
45726cb4
NP
679 VM_BUG_ON(page->index != offset);
680 goto out;
1da177e4
LT
681 }
682 }
683 read_unlock_irq(&mapping->tree_lock);
45726cb4 684out:
1da177e4
LT
685 return page;
686}
1da177e4
LT
687EXPORT_SYMBOL(find_lock_page);
688
689/**
690 * find_or_create_page - locate or add a pagecache page
67be2dd1
MW
691 * @mapping: the page's address_space
692 * @index: the page's index into the mapping
693 * @gfp_mask: page allocation mode
1da177e4
LT
694 *
695 * Locates a page in the pagecache. If the page is not present, a new page
696 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
697 * LRU list. The returned page is locked and has its reference count
698 * incremented.
699 *
700 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
701 * allocation!
702 *
703 * find_or_create_page() returns the desired page's address, or zero on
704 * memory exhaustion.
705 */
706struct page *find_or_create_page(struct address_space *mapping,
57f6b96c 707 pgoff_t index, gfp_t gfp_mask)
1da177e4 708{
eb2be189 709 struct page *page;
1da177e4
LT
710 int err;
711repeat:
712 page = find_lock_page(mapping, index);
713 if (!page) {
eb2be189
NP
714 page = __page_cache_alloc(gfp_mask);
715 if (!page)
716 return NULL;
717 err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
718 if (unlikely(err)) {
719 page_cache_release(page);
720 page = NULL;
721 if (err == -EEXIST)
722 goto repeat;
1da177e4 723 }
1da177e4 724 }
1da177e4
LT
725 return page;
726}
1da177e4
LT
727EXPORT_SYMBOL(find_or_create_page);
728
729/**
730 * find_get_pages - gang pagecache lookup
731 * @mapping: The address_space to search
732 * @start: The starting page index
733 * @nr_pages: The maximum number of pages
734 * @pages: Where the resulting pages are placed
735 *
736 * find_get_pages() will search for and return a group of up to
737 * @nr_pages pages in the mapping. The pages are placed at @pages.
738 * find_get_pages() takes a reference against the returned pages.
739 *
740 * The search returns a group of mapping-contiguous pages with ascending
741 * indexes. There may be holes in the indices due to not-present pages.
742 *
743 * find_get_pages() returns the number of pages which were found.
744 */
745unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
746 unsigned int nr_pages, struct page **pages)
747{
748 unsigned int i;
749 unsigned int ret;
750
751 read_lock_irq(&mapping->tree_lock);
752 ret = radix_tree_gang_lookup(&mapping->page_tree,
753 (void **)pages, start, nr_pages);
754 for (i = 0; i < ret; i++)
755 page_cache_get(pages[i]);
756 read_unlock_irq(&mapping->tree_lock);
757 return ret;
758}
759
ebf43500
JA
760/**
761 * find_get_pages_contig - gang contiguous pagecache lookup
762 * @mapping: The address_space to search
763 * @index: The starting page index
764 * @nr_pages: The maximum number of pages
765 * @pages: Where the resulting pages are placed
766 *
767 * find_get_pages_contig() works exactly like find_get_pages(), except
768 * that the returned number of pages are guaranteed to be contiguous.
769 *
770 * find_get_pages_contig() returns the number of pages which were found.
771 */
772unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
773 unsigned int nr_pages, struct page **pages)
774{
775 unsigned int i;
776 unsigned int ret;
777
778 read_lock_irq(&mapping->tree_lock);
779 ret = radix_tree_gang_lookup(&mapping->page_tree,
780 (void **)pages, index, nr_pages);
781 for (i = 0; i < ret; i++) {
782 if (pages[i]->mapping == NULL || pages[i]->index != index)
783 break;
784
785 page_cache_get(pages[i]);
786 index++;
787 }
788 read_unlock_irq(&mapping->tree_lock);
789 return i;
790}
ef71c15c 791EXPORT_SYMBOL(find_get_pages_contig);
ebf43500 792
485bb99b
RD
793/**
794 * find_get_pages_tag - find and return pages that match @tag
795 * @mapping: the address_space to search
796 * @index: the starting page index
797 * @tag: the tag index
798 * @nr_pages: the maximum number of pages
799 * @pages: where the resulting pages are placed
800 *
1da177e4 801 * Like find_get_pages, except we only return pages which are tagged with
485bb99b 802 * @tag. We update @index to index the next page for the traversal.
1da177e4
LT
803 */
804unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
805 int tag, unsigned int nr_pages, struct page **pages)
806{
807 unsigned int i;
808 unsigned int ret;
809
810 read_lock_irq(&mapping->tree_lock);
811 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
812 (void **)pages, *index, nr_pages, tag);
813 for (i = 0; i < ret; i++)
814 page_cache_get(pages[i]);
815 if (ret)
816 *index = pages[ret - 1]->index + 1;
817 read_unlock_irq(&mapping->tree_lock);
818 return ret;
819}
ef71c15c 820EXPORT_SYMBOL(find_get_pages_tag);
1da177e4 821
485bb99b
RD
822/**
823 * grab_cache_page_nowait - returns locked page at given index in given cache
824 * @mapping: target address_space
825 * @index: the page index
826 *
72fd4a35 827 * Same as grab_cache_page(), but do not wait if the page is unavailable.
1da177e4
LT
828 * This is intended for speculative data generators, where the data can
829 * be regenerated if the page couldn't be grabbed. This routine should
830 * be safe to call while holding the lock for another page.
831 *
832 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
833 * and deadlock against the caller's locked page.
834 */
835struct page *
57f6b96c 836grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
1da177e4
LT
837{
838 struct page *page = find_get_page(mapping, index);
1da177e4
LT
839
840 if (page) {
841 if (!TestSetPageLocked(page))
842 return page;
843 page_cache_release(page);
844 return NULL;
845 }
2ae88149
NP
846 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
847 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
1da177e4
LT
848 page_cache_release(page);
849 page = NULL;
850 }
851 return page;
852}
1da177e4
LT
853EXPORT_SYMBOL(grab_cache_page_nowait);
854
76d42bd9
WF
855/*
856 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
857 * a _large_ part of the i/o request. Imagine the worst scenario:
858 *
859 * ---R__________________________________________B__________
860 * ^ reading here ^ bad block(assume 4k)
861 *
862 * read(R) => miss => readahead(R...B) => media error => frustrating retries
863 * => failing the whole request => read(R) => read(R+1) =>
864 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
865 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
866 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
867 *
868 * It is going insane. Fix it by quickly scaling down the readahead size.
869 */
870static void shrink_readahead_size_eio(struct file *filp,
871 struct file_ra_state *ra)
872{
873 if (!ra->ra_pages)
874 return;
875
876 ra->ra_pages /= 4;
76d42bd9
WF
877}
878
485bb99b 879/**
36e78914 880 * do_generic_file_read - generic file read routine
485bb99b
RD
881 * @filp: the file to read
882 * @ppos: current file position
883 * @desc: read_descriptor
884 * @actor: read method
885 *
1da177e4 886 * This is a generic file read routine, and uses the
485bb99b 887 * mapping->a_ops->readpage() function for the actual low-level stuff.
1da177e4
LT
888 *
889 * This is really ugly. But the goto's actually try to clarify some
890 * of the logic when it comes to error handling etc.
1da177e4 891 */
36e78914
CH
892static void do_generic_file_read(struct file *filp, loff_t *ppos,
893 read_descriptor_t *desc, read_actor_t actor)
1da177e4 894{
36e78914 895 struct address_space *mapping = filp->f_mapping;
1da177e4 896 struct inode *inode = mapping->host;
36e78914 897 struct file_ra_state *ra = &filp->f_ra;
57f6b96c
FW
898 pgoff_t index;
899 pgoff_t last_index;
900 pgoff_t prev_index;
901 unsigned long offset; /* offset into pagecache page */
ec0f1637 902 unsigned int prev_offset;
1da177e4 903 int error;
1da177e4 904
1da177e4 905 index = *ppos >> PAGE_CACHE_SHIFT;
7ff81078
FW
906 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
907 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
1da177e4
LT
908 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
909 offset = *ppos & ~PAGE_CACHE_MASK;
910
1da177e4
LT
911 for (;;) {
912 struct page *page;
57f6b96c 913 pgoff_t end_index;
a32ea1e1 914 loff_t isize;
1da177e4
LT
915 unsigned long nr, ret;
916
1da177e4 917 cond_resched();
1da177e4
LT
918find_page:
919 page = find_get_page(mapping, index);
3ea89ee8 920 if (!page) {
cf914a7d 921 page_cache_sync_readahead(mapping,
7ff81078 922 ra, filp,
3ea89ee8
FW
923 index, last_index - index);
924 page = find_get_page(mapping, index);
925 if (unlikely(page == NULL))
926 goto no_cached_page;
927 }
928 if (PageReadahead(page)) {
cf914a7d 929 page_cache_async_readahead(mapping,
7ff81078 930 ra, filp, page,
3ea89ee8 931 index, last_index - index);
1da177e4
LT
932 }
933 if (!PageUptodate(page))
934 goto page_not_up_to_date;
935page_ok:
a32ea1e1
N
936 /*
937 * i_size must be checked after we know the page is Uptodate.
938 *
939 * Checking i_size after the check allows us to calculate
940 * the correct value for "nr", which means the zero-filled
941 * part of the page is not copied back to userspace (unless
942 * another truncate extends the file - this is desired though).
943 */
944
945 isize = i_size_read(inode);
946 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
947 if (unlikely(!isize || index > end_index)) {
948 page_cache_release(page);
949 goto out;
950 }
951
952 /* nr is the maximum number of bytes to copy from this page */
953 nr = PAGE_CACHE_SIZE;
954 if (index == end_index) {
955 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
956 if (nr <= offset) {
957 page_cache_release(page);
958 goto out;
959 }
960 }
961 nr = nr - offset;
1da177e4
LT
962
963 /* If users can be writing to this page using arbitrary
964 * virtual addresses, take care about potential aliasing
965 * before reading the page on the kernel side.
966 */
967 if (mapping_writably_mapped(mapping))
968 flush_dcache_page(page);
969
970 /*
ec0f1637
JK
971 * When a sequential read accesses a page several times,
972 * only mark it as accessed the first time.
1da177e4 973 */
ec0f1637 974 if (prev_index != index || offset != prev_offset)
1da177e4
LT
975 mark_page_accessed(page);
976 prev_index = index;
977
978 /*
979 * Ok, we have the page, and it's up-to-date, so
980 * now we can copy it to user space...
981 *
982 * The actor routine returns how many bytes were actually used..
983 * NOTE! This may not be the same as how much of a user buffer
984 * we filled up (we may be padding etc), so we can only update
985 * "pos" here (the actor routine has to update the user buffer
986 * pointers and the remaining count).
987 */
988 ret = actor(desc, page, offset, nr);
989 offset += ret;
990 index += offset >> PAGE_CACHE_SHIFT;
991 offset &= ~PAGE_CACHE_MASK;
6ce745ed 992 prev_offset = offset;
1da177e4
LT
993
994 page_cache_release(page);
995 if (ret == nr && desc->count)
996 continue;
997 goto out;
998
999page_not_up_to_date:
1000 /* Get exclusive access to the page ... */
0b94e97a
MW
1001 if (lock_page_killable(page))
1002 goto readpage_eio;
1da177e4 1003
da6052f7 1004 /* Did it get truncated before we got the lock? */
1da177e4
LT
1005 if (!page->mapping) {
1006 unlock_page(page);
1007 page_cache_release(page);
1008 continue;
1009 }
1010
1011 /* Did somebody else fill it already? */
1012 if (PageUptodate(page)) {
1013 unlock_page(page);
1014 goto page_ok;
1015 }
1016
1017readpage:
1018 /* Start the actual read. The read will unlock the page. */
1019 error = mapping->a_ops->readpage(filp, page);
1020
994fc28c
ZB
1021 if (unlikely(error)) {
1022 if (error == AOP_TRUNCATED_PAGE) {
1023 page_cache_release(page);
1024 goto find_page;
1025 }
1da177e4 1026 goto readpage_error;
994fc28c 1027 }
1da177e4
LT
1028
1029 if (!PageUptodate(page)) {
0b94e97a
MW
1030 if (lock_page_killable(page))
1031 goto readpage_eio;
1da177e4
LT
1032 if (!PageUptodate(page)) {
1033 if (page->mapping == NULL) {
1034 /*
1035 * invalidate_inode_pages got it
1036 */
1037 unlock_page(page);
1038 page_cache_release(page);
1039 goto find_page;
1040 }
1041 unlock_page(page);
7ff81078 1042 shrink_readahead_size_eio(filp, ra);
0b94e97a 1043 goto readpage_eio;
1da177e4
LT
1044 }
1045 unlock_page(page);
1046 }
1047
1da177e4
LT
1048 goto page_ok;
1049
0b94e97a
MW
1050readpage_eio:
1051 error = -EIO;
1da177e4
LT
1052readpage_error:
1053 /* UHHUH! A synchronous read error occurred. Report it */
1054 desc->error = error;
1055 page_cache_release(page);
1056 goto out;
1057
1058no_cached_page:
1059 /*
1060 * Ok, it wasn't cached, so we need to create a new
1061 * page..
1062 */
eb2be189
NP
1063 page = page_cache_alloc_cold(mapping);
1064 if (!page) {
1065 desc->error = -ENOMEM;
1066 goto out;
1da177e4 1067 }
eb2be189 1068 error = add_to_page_cache_lru(page, mapping,
1da177e4
LT
1069 index, GFP_KERNEL);
1070 if (error) {
eb2be189 1071 page_cache_release(page);
1da177e4
LT
1072 if (error == -EEXIST)
1073 goto find_page;
1074 desc->error = error;
1075 goto out;
1076 }
1da177e4
LT
1077 goto readpage;
1078 }
1079
1080out:
7ff81078
FW
1081 ra->prev_pos = prev_index;
1082 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1083 ra->prev_pos |= prev_offset;
1da177e4 1084
f4e6b498 1085 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
1da177e4
LT
1086 if (filp)
1087 file_accessed(filp);
1088}
1da177e4
LT
1089
1090int file_read_actor(read_descriptor_t *desc, struct page *page,
1091 unsigned long offset, unsigned long size)
1092{
1093 char *kaddr;
1094 unsigned long left, count = desc->count;
1095
1096 if (size > count)
1097 size = count;
1098
1099 /*
1100 * Faults on the destination of a read are common, so do it before
1101 * taking the kmap.
1102 */
1103 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1104 kaddr = kmap_atomic(page, KM_USER0);
1105 left = __copy_to_user_inatomic(desc->arg.buf,
1106 kaddr + offset, size);
1107 kunmap_atomic(kaddr, KM_USER0);
1108 if (left == 0)
1109 goto success;
1110 }
1111
1112 /* Do it the slow way */
1113 kaddr = kmap(page);
1114 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1115 kunmap(page);
1116
1117 if (left) {
1118 size -= left;
1119 desc->error = -EFAULT;
1120 }
1121success:
1122 desc->count = count - size;
1123 desc->written += size;
1124 desc->arg.buf += size;
1125 return size;
1126}
1127
0ceb3314
DM
1128/*
1129 * Performs necessary checks before doing a write
1130 * @iov: io vector request
1131 * @nr_segs: number of segments in the iovec
1132 * @count: number of bytes to write
1133 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1134 *
1135 * Adjust number of segments and amount of bytes to write (nr_segs should be
1136 * properly initialized first). Returns appropriate error code that caller
1137 * should return or zero in case that write should be allowed.
1138 */
1139int generic_segment_checks(const struct iovec *iov,
1140 unsigned long *nr_segs, size_t *count, int access_flags)
1141{
1142 unsigned long seg;
1143 size_t cnt = 0;
1144 for (seg = 0; seg < *nr_segs; seg++) {
1145 const struct iovec *iv = &iov[seg];
1146
1147 /*
1148 * If any segment has a negative length, or the cumulative
1149 * length ever wraps negative then return -EINVAL.
1150 */
1151 cnt += iv->iov_len;
1152 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1153 return -EINVAL;
1154 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1155 continue;
1156 if (seg == 0)
1157 return -EFAULT;
1158 *nr_segs = seg;
1159 cnt -= iv->iov_len; /* This segment is no good */
1160 break;
1161 }
1162 *count = cnt;
1163 return 0;
1164}
1165EXPORT_SYMBOL(generic_segment_checks);
1166
485bb99b 1167/**
b2abacf3 1168 * generic_file_aio_read - generic filesystem read routine
485bb99b
RD
1169 * @iocb: kernel I/O control block
1170 * @iov: io vector request
1171 * @nr_segs: number of segments in the iovec
b2abacf3 1172 * @pos: current file position
485bb99b 1173 *
1da177e4
LT
1174 * This is the "read()" routine for all filesystems
1175 * that can use the page cache directly.
1176 */
1177ssize_t
543ade1f
BP
1178generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1179 unsigned long nr_segs, loff_t pos)
1da177e4
LT
1180{
1181 struct file *filp = iocb->ki_filp;
1182 ssize_t retval;
1183 unsigned long seg;
1184 size_t count;
543ade1f 1185 loff_t *ppos = &iocb->ki_pos;
1da177e4
LT
1186
1187 count = 0;
0ceb3314
DM
1188 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1189 if (retval)
1190 return retval;
1da177e4
LT
1191
1192 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1193 if (filp->f_flags & O_DIRECT) {
543ade1f 1194 loff_t size;
1da177e4
LT
1195 struct address_space *mapping;
1196 struct inode *inode;
1197
1198 mapping = filp->f_mapping;
1199 inode = mapping->host;
1200 retval = 0;
1201 if (!count)
1202 goto out; /* skip atime */
1203 size = i_size_read(inode);
1204 if (pos < size) {
1205 retval = generic_file_direct_IO(READ, iocb,
1206 iov, pos, nr_segs);
1da177e4
LT
1207 if (retval > 0)
1208 *ppos = pos + retval;
1209 }
0e0bcae3 1210 if (likely(retval != 0)) {
3f1a9aae 1211 file_accessed(filp);
a9e5f4d0 1212 goto out;
0e0bcae3 1213 }
1da177e4
LT
1214 }
1215
1216 retval = 0;
1217 if (count) {
1218 for (seg = 0; seg < nr_segs; seg++) {
1219 read_descriptor_t desc;
1220
1221 desc.written = 0;
1222 desc.arg.buf = iov[seg].iov_base;
1223 desc.count = iov[seg].iov_len;
1224 if (desc.count == 0)
1225 continue;
1226 desc.error = 0;
1227 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1228 retval += desc.written;
39e88ca2
TH
1229 if (desc.error) {
1230 retval = retval ?: desc.error;
1da177e4
LT
1231 break;
1232 }
c44939ec
AM
1233 if (desc.count > 0)
1234 break;
1da177e4
LT
1235 }
1236 }
1237out:
1238 return retval;
1239}
1da177e4
LT
1240EXPORT_SYMBOL(generic_file_aio_read);
1241
1da177e4
LT
1242static ssize_t
1243do_readahead(struct address_space *mapping, struct file *filp,
57f6b96c 1244 pgoff_t index, unsigned long nr)
1da177e4
LT
1245{
1246 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1247 return -EINVAL;
1248
1249 force_page_cache_readahead(mapping, filp, index,
1250 max_sane_readahead(nr));
1251 return 0;
1252}
1253
1254asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1255{
1256 ssize_t ret;
1257 struct file *file;
1258
1259 ret = -EBADF;
1260 file = fget(fd);
1261 if (file) {
1262 if (file->f_mode & FMODE_READ) {
1263 struct address_space *mapping = file->f_mapping;
57f6b96c
FW
1264 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1265 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1da177e4
LT
1266 unsigned long len = end - start + 1;
1267 ret = do_readahead(mapping, file, start, len);
1268 }
1269 fput(file);
1270 }
1271 return ret;
1272}
1273
1274#ifdef CONFIG_MMU
485bb99b
RD
1275/**
1276 * page_cache_read - adds requested page to the page cache if not already there
1277 * @file: file to read
1278 * @offset: page index
1279 *
1da177e4
LT
1280 * This adds the requested page to the page cache if it isn't already there,
1281 * and schedules an I/O to read in its contents from disk.
1282 */
920c7a5d 1283static int page_cache_read(struct file *file, pgoff_t offset)
1da177e4
LT
1284{
1285 struct address_space *mapping = file->f_mapping;
1286 struct page *page;
994fc28c 1287 int ret;
1da177e4 1288
994fc28c
ZB
1289 do {
1290 page = page_cache_alloc_cold(mapping);
1291 if (!page)
1292 return -ENOMEM;
1293
1294 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1295 if (ret == 0)
1296 ret = mapping->a_ops->readpage(file, page);
1297 else if (ret == -EEXIST)
1298 ret = 0; /* losing race to add is OK */
1da177e4 1299
1da177e4 1300 page_cache_release(page);
1da177e4 1301
994fc28c
ZB
1302 } while (ret == AOP_TRUNCATED_PAGE);
1303
1304 return ret;
1da177e4
LT
1305}
1306
1307#define MMAP_LOTSAMISS (100)
1308
485bb99b 1309/**
54cb8821 1310 * filemap_fault - read in file data for page fault handling
d0217ac0
NP
1311 * @vma: vma in which the fault was taken
1312 * @vmf: struct vm_fault containing details of the fault
485bb99b 1313 *
54cb8821 1314 * filemap_fault() is invoked via the vma operations vector for a
1da177e4
LT
1315 * mapped memory region to read in file data during a page fault.
1316 *
1317 * The goto's are kind of ugly, but this streamlines the normal case of having
1318 * it in the page cache, and handles the special cases reasonably without
1319 * having a lot of duplicated code.
1320 */
d0217ac0 1321int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1da177e4
LT
1322{
1323 int error;
54cb8821 1324 struct file *file = vma->vm_file;
1da177e4
LT
1325 struct address_space *mapping = file->f_mapping;
1326 struct file_ra_state *ra = &file->f_ra;
1327 struct inode *inode = mapping->host;
1328 struct page *page;
2004dc8e 1329 pgoff_t size;
54cb8821 1330 int did_readaround = 0;
83c54070 1331 int ret = 0;
1da177e4 1332
1da177e4 1333 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
d0217ac0 1334 if (vmf->pgoff >= size)
5307cc1a 1335 return VM_FAULT_SIGBUS;
1da177e4
LT
1336
1337 /* If we don't want any read-ahead, don't bother */
54cb8821 1338 if (VM_RandomReadHint(vma))
1da177e4
LT
1339 goto no_cached_page;
1340
1da177e4
LT
1341 /*
1342 * Do we have something in the page cache already?
1343 */
1344retry_find:
d0217ac0 1345 page = find_lock_page(mapping, vmf->pgoff);
3ea89ee8
FW
1346 /*
1347 * For sequential accesses, we use the generic readahead logic.
1348 */
1349 if (VM_SequentialReadHint(vma)) {
1350 if (!page) {
cf914a7d 1351 page_cache_sync_readahead(mapping, ra, file,
3ea89ee8
FW
1352 vmf->pgoff, 1);
1353 page = find_lock_page(mapping, vmf->pgoff);
1354 if (!page)
1355 goto no_cached_page;
1356 }
1357 if (PageReadahead(page)) {
cf914a7d 1358 page_cache_async_readahead(mapping, ra, file, page,
3ea89ee8
FW
1359 vmf->pgoff, 1);
1360 }
1361 }
1362
1da177e4
LT
1363 if (!page) {
1364 unsigned long ra_pages;
1365
1da177e4
LT
1366 ra->mmap_miss++;
1367
1368 /*
1369 * Do we miss much more than hit in this file? If so,
1370 * stop bothering with read-ahead. It will only hurt.
1371 */
0bb7ba6b 1372 if (ra->mmap_miss > MMAP_LOTSAMISS)
1da177e4
LT
1373 goto no_cached_page;
1374
1375 /*
1376 * To keep the pgmajfault counter straight, we need to
1377 * check did_readaround, as this is an inner loop.
1378 */
1379 if (!did_readaround) {
d0217ac0 1380 ret = VM_FAULT_MAJOR;
f8891e5e 1381 count_vm_event(PGMAJFAULT);
1da177e4
LT
1382 }
1383 did_readaround = 1;
1384 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1385 if (ra_pages) {
1386 pgoff_t start = 0;
1387
d0217ac0
NP
1388 if (vmf->pgoff > ra_pages / 2)
1389 start = vmf->pgoff - ra_pages / 2;
1da177e4
LT
1390 do_page_cache_readahead(mapping, file, start, ra_pages);
1391 }
d0217ac0 1392 page = find_lock_page(mapping, vmf->pgoff);
1da177e4
LT
1393 if (!page)
1394 goto no_cached_page;
1395 }
1396
1397 if (!did_readaround)
0bb7ba6b 1398 ra->mmap_miss--;
1da177e4
LT
1399
1400 /*
d00806b1
NP
1401 * We have a locked page in the page cache, now we need to check
1402 * that it's up-to-date. If not, it is going to be due to an error.
1da177e4 1403 */
d00806b1 1404 if (unlikely(!PageUptodate(page)))
1da177e4
LT
1405 goto page_not_uptodate;
1406
d00806b1
NP
1407 /* Must recheck i_size under page lock */
1408 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
d0217ac0 1409 if (unlikely(vmf->pgoff >= size)) {
d00806b1 1410 unlock_page(page);
745ad48e 1411 page_cache_release(page);
5307cc1a 1412 return VM_FAULT_SIGBUS;
d00806b1
NP
1413 }
1414
1da177e4
LT
1415 /*
1416 * Found the page and have a reference on it.
1417 */
1418 mark_page_accessed(page);
f4e6b498 1419 ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
d0217ac0 1420 vmf->page = page;
83c54070 1421 return ret | VM_FAULT_LOCKED;
1da177e4 1422
1da177e4
LT
1423no_cached_page:
1424 /*
1425 * We're only likely to ever get here if MADV_RANDOM is in
1426 * effect.
1427 */
d0217ac0 1428 error = page_cache_read(file, vmf->pgoff);
1da177e4
LT
1429
1430 /*
1431 * The page we want has now been added to the page cache.
1432 * In the unlikely event that someone removed it in the
1433 * meantime, we'll just come back here and read it again.
1434 */
1435 if (error >= 0)
1436 goto retry_find;
1437
1438 /*
1439 * An error return from page_cache_read can result if the
1440 * system is low on memory, or a problem occurs while trying
1441 * to schedule I/O.
1442 */
1443 if (error == -ENOMEM)
d0217ac0
NP
1444 return VM_FAULT_OOM;
1445 return VM_FAULT_SIGBUS;
1da177e4
LT
1446
1447page_not_uptodate:
d00806b1 1448 /* IO error path */
1da177e4 1449 if (!did_readaround) {
d0217ac0 1450 ret = VM_FAULT_MAJOR;
f8891e5e 1451 count_vm_event(PGMAJFAULT);
1da177e4 1452 }
1da177e4
LT
1453
1454 /*
1455 * Umm, take care of errors if the page isn't up-to-date.
1456 * Try to re-read it _once_. We do this synchronously,
1457 * because there really aren't any performance issues here
1458 * and we need to check for errors.
1459 */
1da177e4 1460 ClearPageError(page);
994fc28c 1461 error = mapping->a_ops->readpage(file, page);
d00806b1
NP
1462 page_cache_release(page);
1463
1464 if (!error || error == AOP_TRUNCATED_PAGE)
994fc28c 1465 goto retry_find;
1da177e4 1466
d00806b1 1467 /* Things didn't work out. Return zero to tell the mm layer so. */
76d42bd9 1468 shrink_readahead_size_eio(file, ra);
d0217ac0 1469 return VM_FAULT_SIGBUS;
54cb8821
NP
1470}
1471EXPORT_SYMBOL(filemap_fault);
1472
1da177e4 1473struct vm_operations_struct generic_file_vm_ops = {
54cb8821 1474 .fault = filemap_fault,
1da177e4
LT
1475};
1476
1477/* This is used for a general mmap of a disk file */
1478
1479int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1480{
1481 struct address_space *mapping = file->f_mapping;
1482
1483 if (!mapping->a_ops->readpage)
1484 return -ENOEXEC;
1485 file_accessed(file);
1486 vma->vm_ops = &generic_file_vm_ops;
d0217ac0 1487 vma->vm_flags |= VM_CAN_NONLINEAR;
1da177e4
LT
1488 return 0;
1489}
1da177e4
LT
1490
1491/*
1492 * This is for filesystems which do not implement ->writepage.
1493 */
1494int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1495{
1496 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1497 return -EINVAL;
1498 return generic_file_mmap(file, vma);
1499}
1500#else
1501int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1502{
1503 return -ENOSYS;
1504}
1505int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1506{
1507 return -ENOSYS;
1508}
1509#endif /* CONFIG_MMU */
1510
1511EXPORT_SYMBOL(generic_file_mmap);
1512EXPORT_SYMBOL(generic_file_readonly_mmap);
1513
6fe6900e 1514static struct page *__read_cache_page(struct address_space *mapping,
57f6b96c 1515 pgoff_t index,
1da177e4
LT
1516 int (*filler)(void *,struct page*),
1517 void *data)
1518{
eb2be189 1519 struct page *page;
1da177e4
LT
1520 int err;
1521repeat:
1522 page = find_get_page(mapping, index);
1523 if (!page) {
eb2be189
NP
1524 page = page_cache_alloc_cold(mapping);
1525 if (!page)
1526 return ERR_PTR(-ENOMEM);
1527 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1528 if (unlikely(err)) {
1529 page_cache_release(page);
1530 if (err == -EEXIST)
1531 goto repeat;
1da177e4 1532 /* Presumably ENOMEM for radix tree node */
1da177e4
LT
1533 return ERR_PTR(err);
1534 }
1da177e4
LT
1535 err = filler(data, page);
1536 if (err < 0) {
1537 page_cache_release(page);
1538 page = ERR_PTR(err);
1539 }
1540 }
1da177e4
LT
1541 return page;
1542}
1543
7682486b
RD
1544/**
1545 * read_cache_page_async - read into page cache, fill it if needed
1546 * @mapping: the page's address_space
1547 * @index: the page index
1548 * @filler: function to perform the read
1549 * @data: destination for read data
1550 *
6fe6900e
NP
1551 * Same as read_cache_page, but don't wait for page to become unlocked
1552 * after submitting it to the filler.
7682486b
RD
1553 *
1554 * Read into the page cache. If a page already exists, and PageUptodate() is
1555 * not set, try to fill the page but don't wait for it to become unlocked.
1556 *
1557 * If the page does not get brought uptodate, return -EIO.
1da177e4 1558 */
6fe6900e 1559struct page *read_cache_page_async(struct address_space *mapping,
57f6b96c 1560 pgoff_t index,
1da177e4
LT
1561 int (*filler)(void *,struct page*),
1562 void *data)
1563{
1564 struct page *page;
1565 int err;
1566
1567retry:
1568 page = __read_cache_page(mapping, index, filler, data);
1569 if (IS_ERR(page))
c855ff37 1570 return page;
1da177e4
LT
1571 if (PageUptodate(page))
1572 goto out;
1573
1574 lock_page(page);
1575 if (!page->mapping) {
1576 unlock_page(page);
1577 page_cache_release(page);
1578 goto retry;
1579 }
1580 if (PageUptodate(page)) {
1581 unlock_page(page);
1582 goto out;
1583 }
1584 err = filler(data, page);
1585 if (err < 0) {
1586 page_cache_release(page);
c855ff37 1587 return ERR_PTR(err);
1da177e4 1588 }
c855ff37 1589out:
6fe6900e
NP
1590 mark_page_accessed(page);
1591 return page;
1592}
1593EXPORT_SYMBOL(read_cache_page_async);
1594
1595/**
1596 * read_cache_page - read into page cache, fill it if needed
1597 * @mapping: the page's address_space
1598 * @index: the page index
1599 * @filler: function to perform the read
1600 * @data: destination for read data
1601 *
1602 * Read into the page cache. If a page already exists, and PageUptodate() is
1603 * not set, try to fill the page then wait for it to become unlocked.
1604 *
1605 * If the page does not get brought uptodate, return -EIO.
1606 */
1607struct page *read_cache_page(struct address_space *mapping,
57f6b96c 1608 pgoff_t index,
6fe6900e
NP
1609 int (*filler)(void *,struct page*),
1610 void *data)
1611{
1612 struct page *page;
1613
1614 page = read_cache_page_async(mapping, index, filler, data);
1615 if (IS_ERR(page))
1616 goto out;
1617 wait_on_page_locked(page);
1618 if (!PageUptodate(page)) {
1619 page_cache_release(page);
1620 page = ERR_PTR(-EIO);
1621 }
1da177e4
LT
1622 out:
1623 return page;
1624}
1da177e4
LT
1625EXPORT_SYMBOL(read_cache_page);
1626
1da177e4
LT
1627/*
1628 * The logic we want is
1629 *
1630 * if suid or (sgid and xgrp)
1631 * remove privs
1632 */
01de85e0 1633int should_remove_suid(struct dentry *dentry)
1da177e4
LT
1634{
1635 mode_t mode = dentry->d_inode->i_mode;
1636 int kill = 0;
1da177e4
LT
1637
1638 /* suid always must be killed */
1639 if (unlikely(mode & S_ISUID))
1640 kill = ATTR_KILL_SUID;
1641
1642 /*
1643 * sgid without any exec bits is just a mandatory locking mark; leave
1644 * it alone. If some exec bits are set, it's a real sgid; kill it.
1645 */
1646 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1647 kill |= ATTR_KILL_SGID;
1648
01de85e0
JA
1649 if (unlikely(kill && !capable(CAP_FSETID)))
1650 return kill;
1da177e4 1651
01de85e0
JA
1652 return 0;
1653}
d23a147b 1654EXPORT_SYMBOL(should_remove_suid);
01de85e0
JA
1655
1656int __remove_suid(struct dentry *dentry, int kill)
1657{
1658 struct iattr newattrs;
1659
1660 newattrs.ia_valid = ATTR_FORCE | kill;
1661 return notify_change(dentry, &newattrs);
1662}
1663
1664int remove_suid(struct dentry *dentry)
1665{
b5376771
SH
1666 int killsuid = should_remove_suid(dentry);
1667 int killpriv = security_inode_need_killpriv(dentry);
1668 int error = 0;
01de85e0 1669
b5376771
SH
1670 if (killpriv < 0)
1671 return killpriv;
1672 if (killpriv)
1673 error = security_inode_killpriv(dentry);
1674 if (!error && killsuid)
1675 error = __remove_suid(dentry, killsuid);
01de85e0 1676
b5376771 1677 return error;
1da177e4
LT
1678}
1679EXPORT_SYMBOL(remove_suid);
1680
2f718ffc 1681static size_t __iovec_copy_from_user_inatomic(char *vaddr,
1da177e4
LT
1682 const struct iovec *iov, size_t base, size_t bytes)
1683{
1684 size_t copied = 0, left = 0;
1685
1686 while (bytes) {
1687 char __user *buf = iov->iov_base + base;
1688 int copy = min(bytes, iov->iov_len - base);
1689
1690 base = 0;
c22ce143 1691 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
1da177e4
LT
1692 copied += copy;
1693 bytes -= copy;
1694 vaddr += copy;
1695 iov++;
1696
01408c49 1697 if (unlikely(left))
1da177e4 1698 break;
1da177e4
LT
1699 }
1700 return copied - left;
1701}
1702
2f718ffc
NP
1703/*
1704 * Copy as much as we can into the page and return the number of bytes which
1705 * were sucessfully copied. If a fault is encountered then return the number of
1706 * bytes which were copied.
1707 */
1708size_t iov_iter_copy_from_user_atomic(struct page *page,
1709 struct iov_iter *i, unsigned long offset, size_t bytes)
1710{
1711 char *kaddr;
1712 size_t copied;
1713
1714 BUG_ON(!in_atomic());
1715 kaddr = kmap_atomic(page, KM_USER0);
1716 if (likely(i->nr_segs == 1)) {
1717 int left;
1718 char __user *buf = i->iov->iov_base + i->iov_offset;
1719 left = __copy_from_user_inatomic_nocache(kaddr + offset,
1720 buf, bytes);
1721 copied = bytes - left;
1722 } else {
1723 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1724 i->iov, i->iov_offset, bytes);
1725 }
1726 kunmap_atomic(kaddr, KM_USER0);
1727
1728 return copied;
1729}
89e10787 1730EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
2f718ffc
NP
1731
1732/*
1733 * This has the same sideeffects and return value as
1734 * iov_iter_copy_from_user_atomic().
1735 * The difference is that it attempts to resolve faults.
1736 * Page must not be locked.
1737 */
1738size_t iov_iter_copy_from_user(struct page *page,
1739 struct iov_iter *i, unsigned long offset, size_t bytes)
1740{
1741 char *kaddr;
1742 size_t copied;
1743
1744 kaddr = kmap(page);
1745 if (likely(i->nr_segs == 1)) {
1746 int left;
1747 char __user *buf = i->iov->iov_base + i->iov_offset;
1748 left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
1749 copied = bytes - left;
1750 } else {
1751 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1752 i->iov, i->iov_offset, bytes);
1753 }
1754 kunmap(page);
1755 return copied;
1756}
89e10787 1757EXPORT_SYMBOL(iov_iter_copy_from_user);
2f718ffc 1758
f7009264 1759void iov_iter_advance(struct iov_iter *i, size_t bytes)
2f718ffc 1760{
f7009264
NP
1761 BUG_ON(i->count < bytes);
1762
2f718ffc
NP
1763 if (likely(i->nr_segs == 1)) {
1764 i->iov_offset += bytes;
f7009264 1765 i->count -= bytes;
2f718ffc
NP
1766 } else {
1767 const struct iovec *iov = i->iov;
1768 size_t base = i->iov_offset;
1769
124d3b70
NP
1770 /*
1771 * The !iov->iov_len check ensures we skip over unlikely
f7009264 1772 * zero-length segments (without overruning the iovec).
124d3b70 1773 */
f7009264
NP
1774 while (bytes || unlikely(!iov->iov_len && i->count)) {
1775 int copy;
2f718ffc 1776
f7009264
NP
1777 copy = min(bytes, iov->iov_len - base);
1778 BUG_ON(!i->count || i->count < copy);
1779 i->count -= copy;
2f718ffc
NP
1780 bytes -= copy;
1781 base += copy;
1782 if (iov->iov_len == base) {
1783 iov++;
1784 base = 0;
1785 }
1786 }
1787 i->iov = iov;
1788 i->iov_offset = base;
1789 }
1790}
89e10787 1791EXPORT_SYMBOL(iov_iter_advance);
2f718ffc 1792
afddba49
NP
1793/*
1794 * Fault in the first iovec of the given iov_iter, to a maximum length
1795 * of bytes. Returns 0 on success, or non-zero if the memory could not be
1796 * accessed (ie. because it is an invalid address).
1797 *
1798 * writev-intensive code may want this to prefault several iovecs -- that
1799 * would be possible (callers must not rely on the fact that _only_ the
1800 * first iovec will be faulted with the current implementation).
1801 */
1802int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
2f718ffc 1803{
2f718ffc 1804 char __user *buf = i->iov->iov_base + i->iov_offset;
afddba49
NP
1805 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
1806 return fault_in_pages_readable(buf, bytes);
2f718ffc 1807}
89e10787 1808EXPORT_SYMBOL(iov_iter_fault_in_readable);
2f718ffc
NP
1809
1810/*
1811 * Return the count of just the current iov_iter segment.
1812 */
1813size_t iov_iter_single_seg_count(struct iov_iter *i)
1814{
1815 const struct iovec *iov = i->iov;
1816 if (i->nr_segs == 1)
1817 return i->count;
1818 else
1819 return min(i->count, iov->iov_len - i->iov_offset);
1820}
89e10787 1821EXPORT_SYMBOL(iov_iter_single_seg_count);
2f718ffc 1822
1da177e4
LT
1823/*
1824 * Performs necessary checks before doing a write
1825 *
485bb99b 1826 * Can adjust writing position or amount of bytes to write.
1da177e4
LT
1827 * Returns appropriate error code that caller should return or
1828 * zero in case that write should be allowed.
1829 */
1830inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1831{
1832 struct inode *inode = file->f_mapping->host;
1833 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1834
1835 if (unlikely(*pos < 0))
1836 return -EINVAL;
1837
1da177e4
LT
1838 if (!isblk) {
1839 /* FIXME: this is for backwards compatibility with 2.4 */
1840 if (file->f_flags & O_APPEND)
1841 *pos = i_size_read(inode);
1842
1843 if (limit != RLIM_INFINITY) {
1844 if (*pos >= limit) {
1845 send_sig(SIGXFSZ, current, 0);
1846 return -EFBIG;
1847 }
1848 if (*count > limit - (typeof(limit))*pos) {
1849 *count = limit - (typeof(limit))*pos;
1850 }
1851 }
1852 }
1853
1854 /*
1855 * LFS rule
1856 */
1857 if (unlikely(*pos + *count > MAX_NON_LFS &&
1858 !(file->f_flags & O_LARGEFILE))) {
1859 if (*pos >= MAX_NON_LFS) {
1da177e4
LT
1860 return -EFBIG;
1861 }
1862 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1863 *count = MAX_NON_LFS - (unsigned long)*pos;
1864 }
1865 }
1866
1867 /*
1868 * Are we about to exceed the fs block limit ?
1869 *
1870 * If we have written data it becomes a short write. If we have
1871 * exceeded without writing data we send a signal and return EFBIG.
1872 * Linus frestrict idea will clean these up nicely..
1873 */
1874 if (likely(!isblk)) {
1875 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1876 if (*count || *pos > inode->i_sb->s_maxbytes) {
1da177e4
LT
1877 return -EFBIG;
1878 }
1879 /* zero-length writes at ->s_maxbytes are OK */
1880 }
1881
1882 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1883 *count = inode->i_sb->s_maxbytes - *pos;
1884 } else {
9361401e 1885#ifdef CONFIG_BLOCK
1da177e4
LT
1886 loff_t isize;
1887 if (bdev_read_only(I_BDEV(inode)))
1888 return -EPERM;
1889 isize = i_size_read(inode);
1890 if (*pos >= isize) {
1891 if (*count || *pos > isize)
1892 return -ENOSPC;
1893 }
1894
1895 if (*pos + *count > isize)
1896 *count = isize - *pos;
9361401e
DH
1897#else
1898 return -EPERM;
1899#endif
1da177e4
LT
1900 }
1901 return 0;
1902}
1903EXPORT_SYMBOL(generic_write_checks);
1904
afddba49
NP
1905int pagecache_write_begin(struct file *file, struct address_space *mapping,
1906 loff_t pos, unsigned len, unsigned flags,
1907 struct page **pagep, void **fsdata)
1908{
1909 const struct address_space_operations *aops = mapping->a_ops;
1910
1911 if (aops->write_begin) {
1912 return aops->write_begin(file, mapping, pos, len, flags,
1913 pagep, fsdata);
1914 } else {
1915 int ret;
1916 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1917 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1918 struct inode *inode = mapping->host;
1919 struct page *page;
1920again:
1921 page = __grab_cache_page(mapping, index);
1922 *pagep = page;
1923 if (!page)
1924 return -ENOMEM;
1925
1926 if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
1927 /*
1928 * There is no way to resolve a short write situation
1929 * for a !Uptodate page (except by double copying in
1930 * the caller done by generic_perform_write_2copy).
1931 *
1932 * Instead, we have to bring it uptodate here.
1933 */
1934 ret = aops->readpage(file, page);
1935 page_cache_release(page);
1936 if (ret) {
1937 if (ret == AOP_TRUNCATED_PAGE)
1938 goto again;
1939 return ret;
1940 }
1941 goto again;
1942 }
1943
1944 ret = aops->prepare_write(file, page, offset, offset+len);
1945 if (ret) {
55144768 1946 unlock_page(page);
afddba49
NP
1947 page_cache_release(page);
1948 if (pos + len > inode->i_size)
1949 vmtruncate(inode, inode->i_size);
afddba49
NP
1950 }
1951 return ret;
1952 }
1953}
1954EXPORT_SYMBOL(pagecache_write_begin);
1955
1956int pagecache_write_end(struct file *file, struct address_space *mapping,
1957 loff_t pos, unsigned len, unsigned copied,
1958 struct page *page, void *fsdata)
1959{
1960 const struct address_space_operations *aops = mapping->a_ops;
1961 int ret;
1962
1963 if (aops->write_end) {
1964 mark_page_accessed(page);
1965 ret = aops->write_end(file, mapping, pos, len, copied,
1966 page, fsdata);
1967 } else {
1968 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1969 struct inode *inode = mapping->host;
1970
1971 flush_dcache_page(page);
1972 ret = aops->commit_write(file, page, offset, offset+len);
1973 unlock_page(page);
1974 mark_page_accessed(page);
1975 page_cache_release(page);
afddba49
NP
1976
1977 if (ret < 0) {
1978 if (pos + len > inode->i_size)
1979 vmtruncate(inode, inode->i_size);
1980 } else if (ret > 0)
1981 ret = min_t(size_t, copied, ret);
1982 else
1983 ret = copied;
1984 }
1985
1986 return ret;
1987}
1988EXPORT_SYMBOL(pagecache_write_end);
1989
1da177e4
LT
1990ssize_t
1991generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1992 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1993 size_t count, size_t ocount)
1994{
1995 struct file *file = iocb->ki_filp;
1996 struct address_space *mapping = file->f_mapping;
1997 struct inode *inode = mapping->host;
1998 ssize_t written;
1999
2000 if (count != ocount)
2001 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2002
2003 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2004 if (written > 0) {
2005 loff_t end = pos + written;
2006 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2007 i_size_write(inode, end);
2008 mark_inode_dirty(inode);
2009 }
2010 *ppos = end;
2011 }
2012
2013 /*
2014 * Sync the fs metadata but not the minor inode changes and
2015 * of course not the data as we did direct DMA for the IO.
1b1dcc1b 2016 * i_mutex is held, which protects generic_osync_inode() from
8459d86a 2017 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
1da177e4 2018 */
8459d86a
ZB
2019 if ((written >= 0 || written == -EIOCBQUEUED) &&
2020 ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1e8a81c5
HH
2021 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2022 if (err < 0)
2023 written = err;
2024 }
1da177e4
LT
2025 return written;
2026}
2027EXPORT_SYMBOL(generic_file_direct_write);
2028
eb2be189
NP
2029/*
2030 * Find or create a page at the given pagecache position. Return the locked
2031 * page. This function is specifically for buffered writes.
2032 */
afddba49 2033struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index)
eb2be189
NP
2034{
2035 int status;
2036 struct page *page;
2037repeat:
2038 page = find_lock_page(mapping, index);
2039 if (likely(page))
2040 return page;
2041
2042 page = page_cache_alloc(mapping);
2043 if (!page)
2044 return NULL;
2045 status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
2046 if (unlikely(status)) {
2047 page_cache_release(page);
2048 if (status == -EEXIST)
2049 goto repeat;
2050 return NULL;
2051 }
2052 return page;
2053}
afddba49 2054EXPORT_SYMBOL(__grab_cache_page);
eb2be189 2055
afddba49
NP
2056static ssize_t generic_perform_write_2copy(struct file *file,
2057 struct iov_iter *i, loff_t pos)
1da177e4 2058{
ae37461c 2059 struct address_space *mapping = file->f_mapping;
f5e54d6e 2060 const struct address_space_operations *a_ops = mapping->a_ops;
afddba49
NP
2061 struct inode *inode = mapping->host;
2062 long status = 0;
2063 ssize_t written = 0;
1da177e4
LT
2064
2065 do {
08291429 2066 struct page *src_page;
eb2be189 2067 struct page *page;
ae37461c
AM
2068 pgoff_t index; /* Pagecache index for current page */
2069 unsigned long offset; /* Offset into pagecache page */
08291429 2070 unsigned long bytes; /* Bytes to write to page */
ae37461c 2071 size_t copied; /* Bytes copied from user */
1da177e4 2072
ae37461c 2073 offset = (pos & (PAGE_CACHE_SIZE - 1));
1da177e4 2074 index = pos >> PAGE_CACHE_SHIFT;
2f718ffc 2075 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
afddba49 2076 iov_iter_count(i));
41cb8ac0 2077
08291429
NP
2078 /*
2079 * a non-NULL src_page indicates that we're doing the
2080 * copy via get_user_pages and kmap.
2081 */
2082 src_page = NULL;
2083
41cb8ac0
NP
2084 /*
2085 * Bring in the user page that we will copy from _first_.
2086 * Otherwise there's a nasty deadlock on copying from the
2087 * same page as we're writing to, without it being marked
2088 * up-to-date.
08291429
NP
2089 *
2090 * Not only is this an optimisation, but it is also required
2091 * to check that the address is actually valid, when atomic
2092 * usercopies are used, below.
41cb8ac0 2093 */
afddba49 2094 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
08291429
NP
2095 status = -EFAULT;
2096 break;
2097 }
eb2be189
NP
2098
2099 page = __grab_cache_page(mapping, index);
1da177e4
LT
2100 if (!page) {
2101 status = -ENOMEM;
2102 break;
2103 }
2104
08291429
NP
2105 /*
2106 * non-uptodate pages cannot cope with short copies, and we
2107 * cannot take a pagefault with the destination page locked.
2108 * So pin the source page to copy it.
2109 */
674b892e 2110 if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
08291429
NP
2111 unlock_page(page);
2112
2113 src_page = alloc_page(GFP_KERNEL);
2114 if (!src_page) {
2115 page_cache_release(page);
2116 status = -ENOMEM;
2117 break;
2118 }
2119
2120 /*
2121 * Cannot get_user_pages with a page locked for the
2122 * same reason as we can't take a page fault with a
2123 * page locked (as explained below).
2124 */
afddba49 2125 copied = iov_iter_copy_from_user(src_page, i,
2f718ffc 2126 offset, bytes);
08291429
NP
2127 if (unlikely(copied == 0)) {
2128 status = -EFAULT;
2129 page_cache_release(page);
2130 page_cache_release(src_page);
2131 break;
2132 }
2133 bytes = copied;
2134
2135 lock_page(page);
2136 /*
2137 * Can't handle the page going uptodate here, because
2138 * that means we would use non-atomic usercopies, which
2139 * zero out the tail of the page, which can cause
2140 * zeroes to become transiently visible. We could just
2141 * use a non-zeroing copy, but the APIs aren't too
2142 * consistent.
2143 */
2144 if (unlikely(!page->mapping || PageUptodate(page))) {
2145 unlock_page(page);
2146 page_cache_release(page);
2147 page_cache_release(src_page);
2148 continue;
2149 }
08291429
NP
2150 }
2151
1da177e4 2152 status = a_ops->prepare_write(file, page, offset, offset+bytes);
64649a58
NP
2153 if (unlikely(status))
2154 goto fs_write_aop_error;
994fc28c 2155
08291429
NP
2156 if (!src_page) {
2157 /*
2158 * Must not enter the pagefault handler here, because
2159 * we hold the page lock, so we might recursively
2160 * deadlock on the same lock, or get an ABBA deadlock
2161 * against a different lock, or against the mmap_sem
2162 * (which nests outside the page lock). So increment
2163 * preempt count, and use _atomic usercopies.
2164 *
2165 * The page is uptodate so we are OK to encounter a
2166 * short copy: if unmodified parts of the page are
2167 * marked dirty and written out to disk, it doesn't
2168 * really matter.
2169 */
2170 pagefault_disable();
afddba49 2171 copied = iov_iter_copy_from_user_atomic(page, i,
2f718ffc 2172 offset, bytes);
08291429
NP
2173 pagefault_enable();
2174 } else {
2175 void *src, *dst;
2176 src = kmap_atomic(src_page, KM_USER0);
2177 dst = kmap_atomic(page, KM_USER1);
2178 memcpy(dst + offset, src + offset, bytes);
2179 kunmap_atomic(dst, KM_USER1);
2180 kunmap_atomic(src, KM_USER0);
2181 copied = bytes;
2182 }
1da177e4 2183 flush_dcache_page(page);
4a9e5ef1 2184
1da177e4 2185 status = a_ops->commit_write(file, page, offset, offset+bytes);
55144768 2186 if (unlikely(status < 0))
64649a58 2187 goto fs_write_aop_error;
64649a58 2188 if (unlikely(status > 0)) /* filesystem did partial write */
08291429
NP
2189 copied = min_t(size_t, copied, status);
2190
2191 unlock_page(page);
2192 mark_page_accessed(page);
2193 page_cache_release(page);
2194 if (src_page)
2195 page_cache_release(src_page);
64649a58 2196
afddba49 2197 iov_iter_advance(i, copied);
4a9e5ef1 2198 pos += copied;
afddba49 2199 written += copied;
4a9e5ef1 2200
1da177e4
LT
2201 balance_dirty_pages_ratelimited(mapping);
2202 cond_resched();
64649a58
NP
2203 continue;
2204
2205fs_write_aop_error:
55144768 2206 unlock_page(page);
64649a58 2207 page_cache_release(page);
08291429
NP
2208 if (src_page)
2209 page_cache_release(src_page);
64649a58
NP
2210
2211 /*
2212 * prepare_write() may have instantiated a few blocks
2213 * outside i_size. Trim these off again. Don't need
2214 * i_size_read because we hold i_mutex.
2215 */
2216 if (pos + bytes > inode->i_size)
2217 vmtruncate(inode, inode->i_size);
55144768 2218 break;
afddba49
NP
2219 } while (iov_iter_count(i));
2220
2221 return written ? written : status;
2222}
2223
2224static ssize_t generic_perform_write(struct file *file,
2225 struct iov_iter *i, loff_t pos)
2226{
2227 struct address_space *mapping = file->f_mapping;
2228 const struct address_space_operations *a_ops = mapping->a_ops;
2229 long status = 0;
2230 ssize_t written = 0;
674b892e
NP
2231 unsigned int flags = 0;
2232
2233 /*
2234 * Copies from kernel address space cannot fail (NFSD is a big user).
2235 */
2236 if (segment_eq(get_fs(), KERNEL_DS))
2237 flags |= AOP_FLAG_UNINTERRUPTIBLE;
afddba49
NP
2238
2239 do {
2240 struct page *page;
2241 pgoff_t index; /* Pagecache index for current page */
2242 unsigned long offset; /* Offset into pagecache page */
2243 unsigned long bytes; /* Bytes to write to page */
2244 size_t copied; /* Bytes copied from user */
2245 void *fsdata;
2246
2247 offset = (pos & (PAGE_CACHE_SIZE - 1));
2248 index = pos >> PAGE_CACHE_SHIFT;
2249 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2250 iov_iter_count(i));
2251
2252again:
2253
2254 /*
2255 * Bring in the user page that we will copy from _first_.
2256 * Otherwise there's a nasty deadlock on copying from the
2257 * same page as we're writing to, without it being marked
2258 * up-to-date.
2259 *
2260 * Not only is this an optimisation, but it is also required
2261 * to check that the address is actually valid, when atomic
2262 * usercopies are used, below.
2263 */
2264 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2265 status = -EFAULT;
2266 break;
2267 }
2268
674b892e 2269 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
afddba49
NP
2270 &page, &fsdata);
2271 if (unlikely(status))
2272 break;
2273
2274 pagefault_disable();
2275 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2276 pagefault_enable();
2277 flush_dcache_page(page);
2278
2279 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2280 page, fsdata);
2281 if (unlikely(status < 0))
2282 break;
2283 copied = status;
2284
2285 cond_resched();
2286
124d3b70 2287 iov_iter_advance(i, copied);
afddba49
NP
2288 if (unlikely(copied == 0)) {
2289 /*
2290 * If we were unable to copy any data at all, we must
2291 * fall back to a single segment length write.
2292 *
2293 * If we didn't fallback here, we could livelock
2294 * because not all segments in the iov can be copied at
2295 * once without a pagefault.
2296 */
2297 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2298 iov_iter_single_seg_count(i));
2299 goto again;
2300 }
afddba49
NP
2301 pos += copied;
2302 written += copied;
2303
2304 balance_dirty_pages_ratelimited(mapping);
2305
2306 } while (iov_iter_count(i));
2307
2308 return written ? written : status;
2309}
2310
2311ssize_t
2312generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2313 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2314 size_t count, ssize_t written)
2315{
2316 struct file *file = iocb->ki_filp;
2317 struct address_space *mapping = file->f_mapping;
2318 const struct address_space_operations *a_ops = mapping->a_ops;
2319 struct inode *inode = mapping->host;
2320 ssize_t status;
2321 struct iov_iter i;
2322
2323 iov_iter_init(&i, iov, nr_segs, count, written);
2324 if (a_ops->write_begin)
2325 status = generic_perform_write(file, &i, pos);
2326 else
2327 status = generic_perform_write_2copy(file, &i, pos);
1da177e4 2328
1da177e4 2329 if (likely(status >= 0)) {
afddba49
NP
2330 written += status;
2331 *ppos = pos + status;
2332
2333 /*
2334 * For now, when the user asks for O_SYNC, we'll actually give
2335 * O_DSYNC
2336 */
1da177e4
LT
2337 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2338 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2339 status = generic_osync_inode(inode, mapping,
2340 OSYNC_METADATA|OSYNC_DATA);
2341 }
2342 }
2343
2344 /*
2345 * If we get here for O_DIRECT writes then we must have fallen through
2346 * to buffered writes (block instantiation inside i_size). So we sync
2347 * the file data here, to try to honour O_DIRECT expectations.
2348 */
2349 if (unlikely(file->f_flags & O_DIRECT) && written)
2350 status = filemap_write_and_wait(mapping);
2351
1da177e4
LT
2352 return written ? written : status;
2353}
2354EXPORT_SYMBOL(generic_file_buffered_write);
2355
5ce7852c 2356static ssize_t
1da177e4
LT
2357__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2358 unsigned long nr_segs, loff_t *ppos)
2359{
2360 struct file *file = iocb->ki_filp;
fb5527e6 2361 struct address_space * mapping = file->f_mapping;
1da177e4
LT
2362 size_t ocount; /* original count */
2363 size_t count; /* after file limit checks */
2364 struct inode *inode = mapping->host;
1da177e4
LT
2365 loff_t pos;
2366 ssize_t written;
2367 ssize_t err;
2368
2369 ocount = 0;
0ceb3314
DM
2370 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2371 if (err)
2372 return err;
1da177e4
LT
2373
2374 count = ocount;
2375 pos = *ppos;
2376
2377 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2378
2379 /* We can write back this queue in page reclaim */
2380 current->backing_dev_info = mapping->backing_dev_info;
2381 written = 0;
2382
2383 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2384 if (err)
2385 goto out;
2386
2387 if (count == 0)
2388 goto out;
2389
d3ac7f89 2390 err = remove_suid(file->f_path.dentry);
1da177e4
LT
2391 if (err)
2392 goto out;
2393
870f4817 2394 file_update_time(file);
1da177e4
LT
2395
2396 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2397 if (unlikely(file->f_flags & O_DIRECT)) {
fb5527e6
JM
2398 loff_t endbyte;
2399 ssize_t written_buffered;
2400
2401 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2402 ppos, count, ocount);
1da177e4
LT
2403 if (written < 0 || written == count)
2404 goto out;
2405 /*
2406 * direct-io write to a hole: fall through to buffered I/O
2407 * for completing the rest of the request.
2408 */
2409 pos += written;
2410 count -= written;
fb5527e6
JM
2411 written_buffered = generic_file_buffered_write(iocb, iov,
2412 nr_segs, pos, ppos, count,
2413 written);
2414 /*
2415 * If generic_file_buffered_write() retuned a synchronous error
2416 * then we want to return the number of bytes which were
2417 * direct-written, or the error code if that was zero. Note
2418 * that this differs from normal direct-io semantics, which
2419 * will return -EFOO even if some bytes were written.
2420 */
2421 if (written_buffered < 0) {
2422 err = written_buffered;
2423 goto out;
2424 }
1da177e4 2425
fb5527e6
JM
2426 /*
2427 * We need to ensure that the page cache pages are written to
2428 * disk and invalidated to preserve the expected O_DIRECT
2429 * semantics.
2430 */
2431 endbyte = pos + written_buffered - written - 1;
ef51c976
MF
2432 err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
2433 SYNC_FILE_RANGE_WAIT_BEFORE|
2434 SYNC_FILE_RANGE_WRITE|
2435 SYNC_FILE_RANGE_WAIT_AFTER);
fb5527e6
JM
2436 if (err == 0) {
2437 written = written_buffered;
2438 invalidate_mapping_pages(mapping,
2439 pos >> PAGE_CACHE_SHIFT,
2440 endbyte >> PAGE_CACHE_SHIFT);
2441 } else {
2442 /*
2443 * We don't know how much we wrote, so just return
2444 * the number of bytes which were direct-written
2445 */
2446 }
2447 } else {
2448 written = generic_file_buffered_write(iocb, iov, nr_segs,
2449 pos, ppos, count, written);
2450 }
1da177e4
LT
2451out:
2452 current->backing_dev_info = NULL;
2453 return written ? written : err;
2454}
1da177e4 2455
027445c3
BP
2456ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2457 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1da177e4
LT
2458{
2459 struct file *file = iocb->ki_filp;
2460 struct address_space *mapping = file->f_mapping;
2461 struct inode *inode = mapping->host;
2462 ssize_t ret;
1da177e4 2463
027445c3
BP
2464 BUG_ON(iocb->ki_pos != pos);
2465
2466 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2467 &iocb->ki_pos);
1da177e4
LT
2468
2469 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
027445c3 2470 ssize_t err;
1da177e4
LT
2471
2472 err = sync_page_range_nolock(inode, mapping, pos, ret);
2473 if (err < 0)
2474 ret = err;
2475 }
2476 return ret;
2477}
027445c3 2478EXPORT_SYMBOL(generic_file_aio_write_nolock);
1da177e4 2479
027445c3
BP
2480ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2481 unsigned long nr_segs, loff_t pos)
1da177e4
LT
2482{
2483 struct file *file = iocb->ki_filp;
2484 struct address_space *mapping = file->f_mapping;
2485 struct inode *inode = mapping->host;
2486 ssize_t ret;
1da177e4
LT
2487
2488 BUG_ON(iocb->ki_pos != pos);
2489
1b1dcc1b 2490 mutex_lock(&inode->i_mutex);
027445c3
BP
2491 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2492 &iocb->ki_pos);
1b1dcc1b 2493 mutex_unlock(&inode->i_mutex);
1da177e4
LT
2494
2495 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2496 ssize_t err;
2497
2498 err = sync_page_range(inode, mapping, pos, ret);
2499 if (err < 0)
2500 ret = err;
2501 }
2502 return ret;
2503}
2504EXPORT_SYMBOL(generic_file_aio_write);
2505
1da177e4 2506/*
1b1dcc1b 2507 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
1da177e4
LT
2508 * went wrong during pagecache shootdown.
2509 */
5ce7852c 2510static ssize_t
1da177e4
LT
2511generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2512 loff_t offset, unsigned long nr_segs)
2513{
2514 struct file *file = iocb->ki_filp;
2515 struct address_space *mapping = file->f_mapping;
2516 ssize_t retval;
65b8291c
ZB
2517 size_t write_len;
2518 pgoff_t end = 0; /* silence gcc */
1da177e4
LT
2519
2520 /*
2521 * If it's a write, unmap all mmappings of the file up-front. This
2522 * will cause any pte dirty bits to be propagated into the pageframes
2523 * for the subsequent filemap_write_and_wait().
2524 */
2525 if (rw == WRITE) {
2526 write_len = iov_length(iov, nr_segs);
65b8291c 2527 end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
1da177e4
LT
2528 if (mapping_mapped(mapping))
2529 unmap_mapping_range(mapping, offset, write_len, 0);
2530 }
2531
2532 retval = filemap_write_and_wait(mapping);
65b8291c
ZB
2533 if (retval)
2534 goto out;
2535
2536 /*
2537 * After a write we want buffered reads to be sure to go to disk to get
2538 * the new data. We invalidate clean cached page from the region we're
2539 * about to write. We do this *before* the write so that we can return
2540 * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
2541 */
2542 if (rw == WRITE && mapping->nrpages) {
2543 retval = invalidate_inode_pages2_range(mapping,
1da177e4 2544 offset >> PAGE_CACHE_SHIFT, end);
65b8291c
ZB
2545 if (retval)
2546 goto out;
1da177e4 2547 }
65b8291c
ZB
2548
2549 retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
65b8291c
ZB
2550
2551 /*
2552 * Finally, try again to invalidate clean pages which might have been
bdb76ef5
ZB
2553 * cached by non-direct readahead, or faulted in by get_user_pages()
2554 * if the source of the write was an mmap'ed region of the file
2555 * we're writing. Either one is a pretty crazy thing to do,
2556 * so we don't support it 100%. If this invalidation
2557 * fails, tough, the write still worked...
65b8291c
ZB
2558 */
2559 if (rw == WRITE && mapping->nrpages) {
bdb76ef5 2560 invalidate_inode_pages2_range(mapping, offset >> PAGE_CACHE_SHIFT, end);
65b8291c
ZB
2561 }
2562out:
1da177e4
LT
2563 return retval;
2564}
cf9a2ae8
DH
2565
2566/**
2567 * try_to_release_page() - release old fs-specific metadata on a page
2568 *
2569 * @page: the page which the kernel is trying to free
2570 * @gfp_mask: memory allocation flags (and I/O mode)
2571 *
2572 * The address_space is to try to release any data against the page
2573 * (presumably at page->private). If the release was successful, return `1'.
2574 * Otherwise return zero.
2575 *
2576 * The @gfp_mask argument specifies whether I/O may be performed to release
2577 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2578 *
2579 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2580 */
2581int try_to_release_page(struct page *page, gfp_t gfp_mask)
2582{
2583 struct address_space * const mapping = page->mapping;
2584
2585 BUG_ON(!PageLocked(page));
2586 if (PageWriteback(page))
2587 return 0;
2588
2589 if (mapping && mapping->a_ops->releasepage)
2590 return mapping->a_ops->releasepage(page, gfp_mask);
2591 return try_to_free_buffers(page);
2592}
2593
2594EXPORT_SYMBOL(try_to_release_page);