blob: d5fdae2eb183861e4380c5f4367ac298d67966f1 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
12#include <linux/config.h>
13#include <linux/module.h>
14#include <linux/slab.h>
15#include <linux/compiler.h>
16#include <linux/fs.h>
17#include <linux/aio.h>
18#include <linux/kernel_stat.h>
19#include <linux/mm.h>
20#include <linux/swap.h>
21#include <linux/mman.h>
22#include <linux/pagemap.h>
23#include <linux/file.h>
24#include <linux/uio.h>
25#include <linux/hash.h>
26#include <linux/writeback.h>
27#include <linux/pagevec.h>
28#include <linux/blkdev.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31/*
32 * This is needed for the following functions:
33 * - try_to_release_page
34 * - block_invalidatepage
35 * - generic_osync_inode
36 *
37 * FIXME: remove all knowledge of the buffer layer from the core VM
38 */
39#include <linux/buffer_head.h> /* for generic_osync_inode */
40
41#include <asm/uaccess.h>
42#include <asm/mman.h>
43
44/*
45 * Shared mappings implemented 30.11.1994. It's not fully working yet,
46 * though.
47 *
48 * Shared mappings now work. 15.8.1995 Bruno.
49 *
50 * finished 'unifying' the page and buffer cache and SMP-threaded the
51 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
52 *
53 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
54 */
55
56/*
57 * Lock ordering:
58 *
59 * ->i_mmap_lock (vmtruncate)
60 * ->private_lock (__free_pte->__set_page_dirty_buffers)
61 * ->swap_list_lock
62 * ->swap_device_lock (exclusive_swap_page, others)
63 * ->mapping->tree_lock
64 *
65 * ->i_sem
66 * ->i_mmap_lock (truncate->unmap_mapping_range)
67 *
68 * ->mmap_sem
69 * ->i_mmap_lock
70 * ->page_table_lock (various places, mainly in mmap.c)
71 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
72 *
73 * ->mmap_sem
74 * ->lock_page (access_process_vm)
75 *
76 * ->mmap_sem
77 * ->i_sem (msync)
78 *
79 * ->i_sem
80 * ->i_alloc_sem (various)
81 *
82 * ->inode_lock
83 * ->sb_lock (fs/fs-writeback.c)
84 * ->mapping->tree_lock (__sync_single_inode)
85 *
86 * ->i_mmap_lock
87 * ->anon_vma.lock (vma_adjust)
88 *
89 * ->anon_vma.lock
90 * ->page_table_lock (anon_vma_prepare and various)
91 *
92 * ->page_table_lock
93 * ->swap_device_lock (try_to_unmap_one)
94 * ->private_lock (try_to_unmap_one)
95 * ->tree_lock (try_to_unmap_one)
96 * ->zone.lru_lock (follow_page->mark_page_accessed)
97 * ->private_lock (page_remove_rmap->set_page_dirty)
98 * ->tree_lock (page_remove_rmap->set_page_dirty)
99 * ->inode_lock (page_remove_rmap->set_page_dirty)
100 * ->inode_lock (zap_pte_range->set_page_dirty)
101 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
102 *
103 * ->task->proc_lock
104 * ->dcache_lock (proc_pid_lookup)
105 */
106
107/*
108 * Remove a page from the page cache and free it. Caller has to make
109 * sure the page is locked and that nobody else uses it - or that usage
110 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
111 */
112void __remove_from_page_cache(struct page *page)
113{
114 struct address_space *mapping = page->mapping;
115
116 radix_tree_delete(&mapping->page_tree, page->index);
117 page->mapping = NULL;
118 mapping->nrpages--;
119 pagecache_acct(-1);
120}
121
122void remove_from_page_cache(struct page *page)
123{
124 struct address_space *mapping = page->mapping;
125
Matt Mackallcd7619d2005-05-01 08:59:01 -0700126 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
128 write_lock_irq(&mapping->tree_lock);
129 __remove_from_page_cache(page);
130 write_unlock_irq(&mapping->tree_lock);
131}
132
133static int sync_page(void *word)
134{
135 struct address_space *mapping;
136 struct page *page;
137
138 page = container_of((page_flags_t *)word, struct page, flags);
139
140 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700141 * page_mapping() is being called without PG_locked held.
142 * Some knowledge of the state and use of the page is used to
143 * reduce the requirements down to a memory barrier.
144 * The danger here is of a stale page_mapping() return value
145 * indicating a struct address_space different from the one it's
146 * associated with when it is associated with one.
147 * After smp_mb(), it's either the correct page_mapping() for
148 * the page, or an old page_mapping() and the page's own
149 * page_mapping() has gone NULL.
150 * The ->sync_page() address_space operation must tolerate
151 * page_mapping() going NULL. By an amazing coincidence,
152 * this comes about because none of the users of the page
153 * in the ->sync_page() methods make essential use of the
154 * page_mapping(), merely passing the page down to the backing
155 * device's unplug functions when it's non-NULL, which in turn
156 * ignore it for all cases but swap, where only page->private is
157 * of interest. When page_mapping() does go NULL, the entire
158 * call stack gracefully ignores the page and returns.
159 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 */
161 smp_mb();
162 mapping = page_mapping(page);
163 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
164 mapping->a_ops->sync_page(page);
165 io_schedule();
166 return 0;
167}
168
169/**
170 * filemap_fdatawrite_range - start writeback against all of a mapping's
171 * dirty pages that lie within the byte offsets <start, end>
Martin Waitz67be2dd2005-05-01 08:59:26 -0700172 * @mapping: address space structure to write
173 * @start: offset in bytes where the range starts
174 * @end: offset in bytes where the range ends
175 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 *
177 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
178 * opposed to a regular memory * cleansing writeback. The difference between
179 * these two operations is that if a dirty page/buffer is encountered, it must
180 * be waited upon, and not just skipped over.
181 */
182static int __filemap_fdatawrite_range(struct address_space *mapping,
183 loff_t start, loff_t end, int sync_mode)
184{
185 int ret;
186 struct writeback_control wbc = {
187 .sync_mode = sync_mode,
188 .nr_to_write = mapping->nrpages * 2,
189 .start = start,
190 .end = end,
191 };
192
193 if (!mapping_cap_writeback_dirty(mapping))
194 return 0;
195
196 ret = do_writepages(mapping, &wbc);
197 return ret;
198}
199
200static inline int __filemap_fdatawrite(struct address_space *mapping,
201 int sync_mode)
202{
203 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
204}
205
206int filemap_fdatawrite(struct address_space *mapping)
207{
208 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
209}
210EXPORT_SYMBOL(filemap_fdatawrite);
211
212static int filemap_fdatawrite_range(struct address_space *mapping,
213 loff_t start, loff_t end)
214{
215 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
216}
217
218/*
219 * This is a mostly non-blocking flush. Not suitable for data-integrity
220 * purposes - I/O may not be started against all dirty pages.
221 */
222int filemap_flush(struct address_space *mapping)
223{
224 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
225}
226EXPORT_SYMBOL(filemap_flush);
227
228/*
229 * Wait for writeback to complete against pages indexed by start->end
230 * inclusive
231 */
232static int wait_on_page_writeback_range(struct address_space *mapping,
233 pgoff_t start, pgoff_t end)
234{
235 struct pagevec pvec;
236 int nr_pages;
237 int ret = 0;
238 pgoff_t index;
239
240 if (end < start)
241 return 0;
242
243 pagevec_init(&pvec, 0);
244 index = start;
245 while ((index <= end) &&
246 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
247 PAGECACHE_TAG_WRITEBACK,
248 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
249 unsigned i;
250
251 for (i = 0; i < nr_pages; i++) {
252 struct page *page = pvec.pages[i];
253
254 /* until radix tree lookup accepts end_index */
255 if (page->index > end)
256 continue;
257
258 wait_on_page_writeback(page);
259 if (PageError(page))
260 ret = -EIO;
261 }
262 pagevec_release(&pvec);
263 cond_resched();
264 }
265
266 /* Check for outstanding write errors */
267 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
268 ret = -ENOSPC;
269 if (test_and_clear_bit(AS_EIO, &mapping->flags))
270 ret = -EIO;
271
272 return ret;
273}
274
275/*
276 * Write and wait upon all the pages in the passed range. This is a "data
277 * integrity" operation. It waits upon in-flight writeout before starting and
278 * waiting upon new writeout. If there was an IO error, return it.
279 *
280 * We need to re-take i_sem during the generic_osync_inode list walk because
281 * it is otherwise livelockable.
282 */
283int sync_page_range(struct inode *inode, struct address_space *mapping,
284 loff_t pos, size_t count)
285{
286 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
287 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
288 int ret;
289
290 if (!mapping_cap_writeback_dirty(mapping) || !count)
291 return 0;
292 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
293 if (ret == 0) {
294 down(&inode->i_sem);
295 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
296 up(&inode->i_sem);
297 }
298 if (ret == 0)
299 ret = wait_on_page_writeback_range(mapping, start, end);
300 return ret;
301}
302EXPORT_SYMBOL(sync_page_range);
303
304/*
305 * Note: Holding i_sem across sync_page_range_nolock is not a good idea
306 * as it forces O_SYNC writers to different parts of the same file
307 * to be serialised right until io completion.
308 */
309int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
310 loff_t pos, size_t count)
311{
312 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
313 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
314 int ret;
315
316 if (!mapping_cap_writeback_dirty(mapping) || !count)
317 return 0;
318 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
319 if (ret == 0)
320 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
321 if (ret == 0)
322 ret = wait_on_page_writeback_range(mapping, start, end);
323 return ret;
324}
325EXPORT_SYMBOL(sync_page_range_nolock);
326
327/**
328 * filemap_fdatawait - walk the list of under-writeback pages of the given
329 * address space and wait for all of them.
330 *
331 * @mapping: address space structure to wait for
332 */
333int filemap_fdatawait(struct address_space *mapping)
334{
335 loff_t i_size = i_size_read(mapping->host);
336
337 if (i_size == 0)
338 return 0;
339
340 return wait_on_page_writeback_range(mapping, 0,
341 (i_size - 1) >> PAGE_CACHE_SHIFT);
342}
343EXPORT_SYMBOL(filemap_fdatawait);
344
345int filemap_write_and_wait(struct address_space *mapping)
346{
347 int retval = 0;
348
349 if (mapping->nrpages) {
350 retval = filemap_fdatawrite(mapping);
351 if (retval == 0)
352 retval = filemap_fdatawait(mapping);
353 }
354 return retval;
355}
356
357int filemap_write_and_wait_range(struct address_space *mapping,
358 loff_t lstart, loff_t lend)
359{
360 int retval = 0;
361
362 if (mapping->nrpages) {
363 retval = __filemap_fdatawrite_range(mapping, lstart, lend,
364 WB_SYNC_ALL);
365 if (retval == 0)
366 retval = wait_on_page_writeback_range(mapping,
367 lstart >> PAGE_CACHE_SHIFT,
368 lend >> PAGE_CACHE_SHIFT);
369 }
370 return retval;
371}
372
373/*
374 * This function is used to add newly allocated pagecache pages:
375 * the page is new, so we can just run SetPageLocked() against it.
376 * The other page state flags were set by rmqueue().
377 *
378 * This function does not add the page to the LRU. The caller must do that.
379 */
380int add_to_page_cache(struct page *page, struct address_space *mapping,
381 pgoff_t offset, int gfp_mask)
382{
383 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
384
385 if (error == 0) {
386 write_lock_irq(&mapping->tree_lock);
387 error = radix_tree_insert(&mapping->page_tree, offset, page);
388 if (!error) {
389 page_cache_get(page);
390 SetPageLocked(page);
391 page->mapping = mapping;
392 page->index = offset;
393 mapping->nrpages++;
394 pagecache_acct(1);
395 }
396 write_unlock_irq(&mapping->tree_lock);
397 radix_tree_preload_end();
398 }
399 return error;
400}
401
402EXPORT_SYMBOL(add_to_page_cache);
403
404int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
405 pgoff_t offset, int gfp_mask)
406{
407 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
408 if (ret == 0)
409 lru_cache_add(page);
410 return ret;
411}
412
413/*
414 * In order to wait for pages to become available there must be
415 * waitqueues associated with pages. By using a hash table of
416 * waitqueues where the bucket discipline is to maintain all
417 * waiters on the same queue and wake all when any of the pages
418 * become available, and for the woken contexts to check to be
419 * sure the appropriate page became available, this saves space
420 * at a cost of "thundering herd" phenomena during rare hash
421 * collisions.
422 */
423static wait_queue_head_t *page_waitqueue(struct page *page)
424{
425 const struct zone *zone = page_zone(page);
426
427 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
428}
429
430static inline void wake_up_page(struct page *page, int bit)
431{
432 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
433}
434
435void fastcall wait_on_page_bit(struct page *page, int bit_nr)
436{
437 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
438
439 if (test_bit(bit_nr, &page->flags))
440 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
441 TASK_UNINTERRUPTIBLE);
442}
443EXPORT_SYMBOL(wait_on_page_bit);
444
445/**
446 * unlock_page() - unlock a locked page
447 *
448 * @page: the page
449 *
450 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
451 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
452 * mechananism between PageLocked pages and PageWriteback pages is shared.
453 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
454 *
455 * The first mb is necessary to safely close the critical section opened by the
456 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
457 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
458 * parallel wait_on_page_locked()).
459 */
460void fastcall unlock_page(struct page *page)
461{
462 smp_mb__before_clear_bit();
463 if (!TestClearPageLocked(page))
464 BUG();
465 smp_mb__after_clear_bit();
466 wake_up_page(page, PG_locked);
467}
468EXPORT_SYMBOL(unlock_page);
469
470/*
471 * End writeback against a page.
472 */
473void end_page_writeback(struct page *page)
474{
475 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
476 if (!test_clear_page_writeback(page))
477 BUG();
478 }
479 smp_mb__after_clear_bit();
480 wake_up_page(page, PG_writeback);
481}
482EXPORT_SYMBOL(end_page_writeback);
483
484/*
485 * Get a lock on the page, assuming we need to sleep to get it.
486 *
487 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
488 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
489 * chances are that on the second loop, the block layer's plug list is empty,
490 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
491 */
492void fastcall __lock_page(struct page *page)
493{
494 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
495
496 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
497 TASK_UNINTERRUPTIBLE);
498}
499EXPORT_SYMBOL(__lock_page);
500
501/*
502 * a rather lightweight function, finding and getting a reference to a
503 * hashed page atomically.
504 */
505struct page * find_get_page(struct address_space *mapping, unsigned long offset)
506{
507 struct page *page;
508
509 read_lock_irq(&mapping->tree_lock);
510 page = radix_tree_lookup(&mapping->page_tree, offset);
511 if (page)
512 page_cache_get(page);
513 read_unlock_irq(&mapping->tree_lock);
514 return page;
515}
516
517EXPORT_SYMBOL(find_get_page);
518
519/*
520 * Same as above, but trylock it instead of incrementing the count.
521 */
522struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
523{
524 struct page *page;
525
526 read_lock_irq(&mapping->tree_lock);
527 page = radix_tree_lookup(&mapping->page_tree, offset);
528 if (page && TestSetPageLocked(page))
529 page = NULL;
530 read_unlock_irq(&mapping->tree_lock);
531 return page;
532}
533
534EXPORT_SYMBOL(find_trylock_page);
535
536/**
537 * find_lock_page - locate, pin and lock a pagecache page
538 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700539 * @mapping: the address_space to search
540 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541 *
542 * Locates the desired pagecache page, locks it, increments its reference
543 * count and returns its address.
544 *
545 * Returns zero if the page was not present. find_lock_page() may sleep.
546 */
547struct page *find_lock_page(struct address_space *mapping,
548 unsigned long offset)
549{
550 struct page *page;
551
552 read_lock_irq(&mapping->tree_lock);
553repeat:
554 page = radix_tree_lookup(&mapping->page_tree, offset);
555 if (page) {
556 page_cache_get(page);
557 if (TestSetPageLocked(page)) {
558 read_unlock_irq(&mapping->tree_lock);
559 lock_page(page);
560 read_lock_irq(&mapping->tree_lock);
561
562 /* Has the page been truncated while we slept? */
563 if (page->mapping != mapping || page->index != offset) {
564 unlock_page(page);
565 page_cache_release(page);
566 goto repeat;
567 }
568 }
569 }
570 read_unlock_irq(&mapping->tree_lock);
571 return page;
572}
573
574EXPORT_SYMBOL(find_lock_page);
575
576/**
577 * find_or_create_page - locate or add a pagecache page
578 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700579 * @mapping: the page's address_space
580 * @index: the page's index into the mapping
581 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 *
583 * Locates a page in the pagecache. If the page is not present, a new page
584 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
585 * LRU list. The returned page is locked and has its reference count
586 * incremented.
587 *
588 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
589 * allocation!
590 *
591 * find_or_create_page() returns the desired page's address, or zero on
592 * memory exhaustion.
593 */
594struct page *find_or_create_page(struct address_space *mapping,
595 unsigned long index, unsigned int gfp_mask)
596{
597 struct page *page, *cached_page = NULL;
598 int err;
599repeat:
600 page = find_lock_page(mapping, index);
601 if (!page) {
602 if (!cached_page) {
603 cached_page = alloc_page(gfp_mask);
604 if (!cached_page)
605 return NULL;
606 }
607 err = add_to_page_cache_lru(cached_page, mapping,
608 index, gfp_mask);
609 if (!err) {
610 page = cached_page;
611 cached_page = NULL;
612 } else if (err == -EEXIST)
613 goto repeat;
614 }
615 if (cached_page)
616 page_cache_release(cached_page);
617 return page;
618}
619
620EXPORT_SYMBOL(find_or_create_page);
621
622/**
623 * find_get_pages - gang pagecache lookup
624 * @mapping: The address_space to search
625 * @start: The starting page index
626 * @nr_pages: The maximum number of pages
627 * @pages: Where the resulting pages are placed
628 *
629 * find_get_pages() will search for and return a group of up to
630 * @nr_pages pages in the mapping. The pages are placed at @pages.
631 * find_get_pages() takes a reference against the returned pages.
632 *
633 * The search returns a group of mapping-contiguous pages with ascending
634 * indexes. There may be holes in the indices due to not-present pages.
635 *
636 * find_get_pages() returns the number of pages which were found.
637 */
638unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
639 unsigned int nr_pages, struct page **pages)
640{
641 unsigned int i;
642 unsigned int ret;
643
644 read_lock_irq(&mapping->tree_lock);
645 ret = radix_tree_gang_lookup(&mapping->page_tree,
646 (void **)pages, start, nr_pages);
647 for (i = 0; i < ret; i++)
648 page_cache_get(pages[i]);
649 read_unlock_irq(&mapping->tree_lock);
650 return ret;
651}
652
653/*
654 * Like find_get_pages, except we only return pages which are tagged with
655 * `tag'. We update *index to index the next page for the traversal.
656 */
657unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
658 int tag, unsigned int nr_pages, struct page **pages)
659{
660 unsigned int i;
661 unsigned int ret;
662
663 read_lock_irq(&mapping->tree_lock);
664 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
665 (void **)pages, *index, nr_pages, tag);
666 for (i = 0; i < ret; i++)
667 page_cache_get(pages[i]);
668 if (ret)
669 *index = pages[ret - 1]->index + 1;
670 read_unlock_irq(&mapping->tree_lock);
671 return ret;
672}
673
674/*
675 * Same as grab_cache_page, but do not wait if the page is unavailable.
676 * This is intended for speculative data generators, where the data can
677 * be regenerated if the page couldn't be grabbed. This routine should
678 * be safe to call while holding the lock for another page.
679 *
680 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
681 * and deadlock against the caller's locked page.
682 */
683struct page *
684grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
685{
686 struct page *page = find_get_page(mapping, index);
687 unsigned int gfp_mask;
688
689 if (page) {
690 if (!TestSetPageLocked(page))
691 return page;
692 page_cache_release(page);
693 return NULL;
694 }
695 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
696 page = alloc_pages(gfp_mask, 0);
697 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
698 page_cache_release(page);
699 page = NULL;
700 }
701 return page;
702}
703
704EXPORT_SYMBOL(grab_cache_page_nowait);
705
706/*
707 * This is a generic file read routine, and uses the
708 * mapping->a_ops->readpage() function for the actual low-level
709 * stuff.
710 *
711 * This is really ugly. But the goto's actually try to clarify some
712 * of the logic when it comes to error handling etc.
713 *
714 * Note the struct file* is only passed for the use of readpage. It may be
715 * NULL.
716 */
717void do_generic_mapping_read(struct address_space *mapping,
718 struct file_ra_state *_ra,
719 struct file *filp,
720 loff_t *ppos,
721 read_descriptor_t *desc,
722 read_actor_t actor)
723{
724 struct inode *inode = mapping->host;
725 unsigned long index;
726 unsigned long end_index;
727 unsigned long offset;
728 unsigned long last_index;
729 unsigned long next_index;
730 unsigned long prev_index;
731 loff_t isize;
732 struct page *cached_page;
733 int error;
734 struct file_ra_state ra = *_ra;
735
736 cached_page = NULL;
737 index = *ppos >> PAGE_CACHE_SHIFT;
738 next_index = index;
739 prev_index = ra.prev_page;
740 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
741 offset = *ppos & ~PAGE_CACHE_MASK;
742
743 isize = i_size_read(inode);
744 if (!isize)
745 goto out;
746
747 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
748 for (;;) {
749 struct page *page;
750 unsigned long nr, ret;
751
752 /* nr is the maximum number of bytes to copy from this page */
753 nr = PAGE_CACHE_SIZE;
754 if (index >= end_index) {
755 if (index > end_index)
756 goto out;
757 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
758 if (nr <= offset) {
759 goto out;
760 }
761 }
762 nr = nr - offset;
763
764 cond_resched();
765 if (index == next_index)
766 next_index = page_cache_readahead(mapping, &ra, filp,
767 index, last_index - index);
768
769find_page:
770 page = find_get_page(mapping, index);
771 if (unlikely(page == NULL)) {
772 handle_ra_miss(mapping, &ra, index);
773 goto no_cached_page;
774 }
775 if (!PageUptodate(page))
776 goto page_not_up_to_date;
777page_ok:
778
779 /* If users can be writing to this page using arbitrary
780 * virtual addresses, take care about potential aliasing
781 * before reading the page on the kernel side.
782 */
783 if (mapping_writably_mapped(mapping))
784 flush_dcache_page(page);
785
786 /*
787 * When (part of) the same page is read multiple times
788 * in succession, only mark it as accessed the first time.
789 */
790 if (prev_index != index)
791 mark_page_accessed(page);
792 prev_index = index;
793
794 /*
795 * Ok, we have the page, and it's up-to-date, so
796 * now we can copy it to user space...
797 *
798 * The actor routine returns how many bytes were actually used..
799 * NOTE! This may not be the same as how much of a user buffer
800 * we filled up (we may be padding etc), so we can only update
801 * "pos" here (the actor routine has to update the user buffer
802 * pointers and the remaining count).
803 */
804 ret = actor(desc, page, offset, nr);
805 offset += ret;
806 index += offset >> PAGE_CACHE_SHIFT;
807 offset &= ~PAGE_CACHE_MASK;
808
809 page_cache_release(page);
810 if (ret == nr && desc->count)
811 continue;
812 goto out;
813
814page_not_up_to_date:
815 /* Get exclusive access to the page ... */
816 lock_page(page);
817
818 /* Did it get unhashed before we got the lock? */
819 if (!page->mapping) {
820 unlock_page(page);
821 page_cache_release(page);
822 continue;
823 }
824
825 /* Did somebody else fill it already? */
826 if (PageUptodate(page)) {
827 unlock_page(page);
828 goto page_ok;
829 }
830
831readpage:
832 /* Start the actual read. The read will unlock the page. */
833 error = mapping->a_ops->readpage(filp, page);
834
835 if (unlikely(error))
836 goto readpage_error;
837
838 if (!PageUptodate(page)) {
839 lock_page(page);
840 if (!PageUptodate(page)) {
841 if (page->mapping == NULL) {
842 /*
843 * invalidate_inode_pages got it
844 */
845 unlock_page(page);
846 page_cache_release(page);
847 goto find_page;
848 }
849 unlock_page(page);
850 error = -EIO;
851 goto readpage_error;
852 }
853 unlock_page(page);
854 }
855
856 /*
857 * i_size must be checked after we have done ->readpage.
858 *
859 * Checking i_size after the readpage allows us to calculate
860 * the correct value for "nr", which means the zero-filled
861 * part of the page is not copied back to userspace (unless
862 * another truncate extends the file - this is desired though).
863 */
864 isize = i_size_read(inode);
865 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
866 if (unlikely(!isize || index > end_index)) {
867 page_cache_release(page);
868 goto out;
869 }
870
871 /* nr is the maximum number of bytes to copy from this page */
872 nr = PAGE_CACHE_SIZE;
873 if (index == end_index) {
874 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
875 if (nr <= offset) {
876 page_cache_release(page);
877 goto out;
878 }
879 }
880 nr = nr - offset;
881 goto page_ok;
882
883readpage_error:
884 /* UHHUH! A synchronous read error occurred. Report it */
885 desc->error = error;
886 page_cache_release(page);
887 goto out;
888
889no_cached_page:
890 /*
891 * Ok, it wasn't cached, so we need to create a new
892 * page..
893 */
894 if (!cached_page) {
895 cached_page = page_cache_alloc_cold(mapping);
896 if (!cached_page) {
897 desc->error = -ENOMEM;
898 goto out;
899 }
900 }
901 error = add_to_page_cache_lru(cached_page, mapping,
902 index, GFP_KERNEL);
903 if (error) {
904 if (error == -EEXIST)
905 goto find_page;
906 desc->error = error;
907 goto out;
908 }
909 page = cached_page;
910 cached_page = NULL;
911 goto readpage;
912 }
913
914out:
915 *_ra = ra;
916
917 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
918 if (cached_page)
919 page_cache_release(cached_page);
920 if (filp)
921 file_accessed(filp);
922}
923
924EXPORT_SYMBOL(do_generic_mapping_read);
925
926int file_read_actor(read_descriptor_t *desc, struct page *page,
927 unsigned long offset, unsigned long size)
928{
929 char *kaddr;
930 unsigned long left, count = desc->count;
931
932 if (size > count)
933 size = count;
934
935 /*
936 * Faults on the destination of a read are common, so do it before
937 * taking the kmap.
938 */
939 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
940 kaddr = kmap_atomic(page, KM_USER0);
941 left = __copy_to_user_inatomic(desc->arg.buf,
942 kaddr + offset, size);
943 kunmap_atomic(kaddr, KM_USER0);
944 if (left == 0)
945 goto success;
946 }
947
948 /* Do it the slow way */
949 kaddr = kmap(page);
950 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
951 kunmap(page);
952
953 if (left) {
954 size -= left;
955 desc->error = -EFAULT;
956 }
957success:
958 desc->count = count - size;
959 desc->written += size;
960 desc->arg.buf += size;
961 return size;
962}
963
964/*
965 * This is the "read()" routine for all filesystems
966 * that can use the page cache directly.
967 */
968ssize_t
969__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
970 unsigned long nr_segs, loff_t *ppos)
971{
972 struct file *filp = iocb->ki_filp;
973 ssize_t retval;
974 unsigned long seg;
975 size_t count;
976
977 count = 0;
978 for (seg = 0; seg < nr_segs; seg++) {
979 const struct iovec *iv = &iov[seg];
980
981 /*
982 * If any segment has a negative length, or the cumulative
983 * length ever wraps negative then return -EINVAL.
984 */
985 count += iv->iov_len;
986 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
987 return -EINVAL;
988 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
989 continue;
990 if (seg == 0)
991 return -EFAULT;
992 nr_segs = seg;
993 count -= iv->iov_len; /* This segment is no good */
994 break;
995 }
996
997 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
998 if (filp->f_flags & O_DIRECT) {
999 loff_t pos = *ppos, size;
1000 struct address_space *mapping;
1001 struct inode *inode;
1002
1003 mapping = filp->f_mapping;
1004 inode = mapping->host;
1005 retval = 0;
1006 if (!count)
1007 goto out; /* skip atime */
1008 size = i_size_read(inode);
1009 if (pos < size) {
1010 retval = generic_file_direct_IO(READ, iocb,
1011 iov, pos, nr_segs);
1012 if (retval >= 0 && !is_sync_kiocb(iocb))
1013 retval = -EIOCBQUEUED;
1014 if (retval > 0)
1015 *ppos = pos + retval;
1016 }
1017 file_accessed(filp);
1018 goto out;
1019 }
1020
1021 retval = 0;
1022 if (count) {
1023 for (seg = 0; seg < nr_segs; seg++) {
1024 read_descriptor_t desc;
1025
1026 desc.written = 0;
1027 desc.arg.buf = iov[seg].iov_base;
1028 desc.count = iov[seg].iov_len;
1029 if (desc.count == 0)
1030 continue;
1031 desc.error = 0;
1032 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1033 retval += desc.written;
1034 if (!retval) {
1035 retval = desc.error;
1036 break;
1037 }
1038 }
1039 }
1040out:
1041 return retval;
1042}
1043
1044EXPORT_SYMBOL(__generic_file_aio_read);
1045
1046ssize_t
1047generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1048{
1049 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1050
1051 BUG_ON(iocb->ki_pos != pos);
1052 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1053}
1054
1055EXPORT_SYMBOL(generic_file_aio_read);
1056
1057ssize_t
1058generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1059{
1060 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1061 struct kiocb kiocb;
1062 ssize_t ret;
1063
1064 init_sync_kiocb(&kiocb, filp);
1065 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1066 if (-EIOCBQUEUED == ret)
1067 ret = wait_on_sync_kiocb(&kiocb);
1068 return ret;
1069}
1070
1071EXPORT_SYMBOL(generic_file_read);
1072
1073int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1074{
1075 ssize_t written;
1076 unsigned long count = desc->count;
1077 struct file *file = desc->arg.data;
1078
1079 if (size > count)
1080 size = count;
1081
1082 written = file->f_op->sendpage(file, page, offset,
1083 size, &file->f_pos, size<count);
1084 if (written < 0) {
1085 desc->error = written;
1086 written = 0;
1087 }
1088 desc->count = count - written;
1089 desc->written += written;
1090 return written;
1091}
1092
1093ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1094 size_t count, read_actor_t actor, void *target)
1095{
1096 read_descriptor_t desc;
1097
1098 if (!count)
1099 return 0;
1100
1101 desc.written = 0;
1102 desc.count = count;
1103 desc.arg.data = target;
1104 desc.error = 0;
1105
1106 do_generic_file_read(in_file, ppos, &desc, actor);
1107 if (desc.written)
1108 return desc.written;
1109 return desc.error;
1110}
1111
1112EXPORT_SYMBOL(generic_file_sendfile);
1113
1114static ssize_t
1115do_readahead(struct address_space *mapping, struct file *filp,
1116 unsigned long index, unsigned long nr)
1117{
1118 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1119 return -EINVAL;
1120
1121 force_page_cache_readahead(mapping, filp, index,
1122 max_sane_readahead(nr));
1123 return 0;
1124}
1125
1126asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1127{
1128 ssize_t ret;
1129 struct file *file;
1130
1131 ret = -EBADF;
1132 file = fget(fd);
1133 if (file) {
1134 if (file->f_mode & FMODE_READ) {
1135 struct address_space *mapping = file->f_mapping;
1136 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1137 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1138 unsigned long len = end - start + 1;
1139 ret = do_readahead(mapping, file, start, len);
1140 }
1141 fput(file);
1142 }
1143 return ret;
1144}
1145
1146#ifdef CONFIG_MMU
1147/*
1148 * This adds the requested page to the page cache if it isn't already there,
1149 * and schedules an I/O to read in its contents from disk.
1150 */
1151static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1152static int fastcall page_cache_read(struct file * file, unsigned long offset)
1153{
1154 struct address_space *mapping = file->f_mapping;
1155 struct page *page;
1156 int error;
1157
1158 page = page_cache_alloc_cold(mapping);
1159 if (!page)
1160 return -ENOMEM;
1161
1162 error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1163 if (!error) {
1164 error = mapping->a_ops->readpage(file, page);
1165 page_cache_release(page);
1166 return error;
1167 }
1168
1169 /*
1170 * We arrive here in the unlikely event that someone
1171 * raced with us and added our page to the cache first
1172 * or we are out of memory for radix-tree nodes.
1173 */
1174 page_cache_release(page);
1175 return error == -EEXIST ? 0 : error;
1176}
1177
1178#define MMAP_LOTSAMISS (100)
1179
1180/*
1181 * filemap_nopage() is invoked via the vma operations vector for a
1182 * mapped memory region to read in file data during a page fault.
1183 *
1184 * The goto's are kind of ugly, but this streamlines the normal case of having
1185 * it in the page cache, and handles the special cases reasonably without
1186 * having a lot of duplicated code.
1187 */
1188struct page *filemap_nopage(struct vm_area_struct *area,
1189 unsigned long address, int *type)
1190{
1191 int error;
1192 struct file *file = area->vm_file;
1193 struct address_space *mapping = file->f_mapping;
1194 struct file_ra_state *ra = &file->f_ra;
1195 struct inode *inode = mapping->host;
1196 struct page *page;
1197 unsigned long size, pgoff;
1198 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1199
1200 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1201
1202retry_all:
1203 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1204 if (pgoff >= size)
1205 goto outside_data_content;
1206
1207 /* If we don't want any read-ahead, don't bother */
1208 if (VM_RandomReadHint(area))
1209 goto no_cached_page;
1210
1211 /*
1212 * The readahead code wants to be told about each and every page
1213 * so it can build and shrink its windows appropriately
1214 *
1215 * For sequential accesses, we use the generic readahead logic.
1216 */
1217 if (VM_SequentialReadHint(area))
1218 page_cache_readahead(mapping, ra, file, pgoff, 1);
1219
1220 /*
1221 * Do we have something in the page cache already?
1222 */
1223retry_find:
1224 page = find_get_page(mapping, pgoff);
1225 if (!page) {
1226 unsigned long ra_pages;
1227
1228 if (VM_SequentialReadHint(area)) {
1229 handle_ra_miss(mapping, ra, pgoff);
1230 goto no_cached_page;
1231 }
1232 ra->mmap_miss++;
1233
1234 /*
1235 * Do we miss much more than hit in this file? If so,
1236 * stop bothering with read-ahead. It will only hurt.
1237 */
1238 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1239 goto no_cached_page;
1240
1241 /*
1242 * To keep the pgmajfault counter straight, we need to
1243 * check did_readaround, as this is an inner loop.
1244 */
1245 if (!did_readaround) {
1246 majmin = VM_FAULT_MAJOR;
1247 inc_page_state(pgmajfault);
1248 }
1249 did_readaround = 1;
1250 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1251 if (ra_pages) {
1252 pgoff_t start = 0;
1253
1254 if (pgoff > ra_pages / 2)
1255 start = pgoff - ra_pages / 2;
1256 do_page_cache_readahead(mapping, file, start, ra_pages);
1257 }
1258 page = find_get_page(mapping, pgoff);
1259 if (!page)
1260 goto no_cached_page;
1261 }
1262
1263 if (!did_readaround)
1264 ra->mmap_hit++;
1265
1266 /*
1267 * Ok, found a page in the page cache, now we need to check
1268 * that it's up-to-date.
1269 */
1270 if (!PageUptodate(page))
1271 goto page_not_uptodate;
1272
1273success:
1274 /*
1275 * Found the page and have a reference on it.
1276 */
1277 mark_page_accessed(page);
1278 if (type)
1279 *type = majmin;
1280 return page;
1281
1282outside_data_content:
1283 /*
1284 * An external ptracer can access pages that normally aren't
1285 * accessible..
1286 */
1287 if (area->vm_mm == current->mm)
1288 return NULL;
1289 /* Fall through to the non-read-ahead case */
1290no_cached_page:
1291 /*
1292 * We're only likely to ever get here if MADV_RANDOM is in
1293 * effect.
1294 */
1295 error = page_cache_read(file, pgoff);
1296 grab_swap_token();
1297
1298 /*
1299 * The page we want has now been added to the page cache.
1300 * In the unlikely event that someone removed it in the
1301 * meantime, we'll just come back here and read it again.
1302 */
1303 if (error >= 0)
1304 goto retry_find;
1305
1306 /*
1307 * An error return from page_cache_read can result if the
1308 * system is low on memory, or a problem occurs while trying
1309 * to schedule I/O.
1310 */
1311 if (error == -ENOMEM)
1312 return NOPAGE_OOM;
1313 return NULL;
1314
1315page_not_uptodate:
1316 if (!did_readaround) {
1317 majmin = VM_FAULT_MAJOR;
1318 inc_page_state(pgmajfault);
1319 }
1320 lock_page(page);
1321
1322 /* Did it get unhashed while we waited for it? */
1323 if (!page->mapping) {
1324 unlock_page(page);
1325 page_cache_release(page);
1326 goto retry_all;
1327 }
1328
1329 /* Did somebody else get it up-to-date? */
1330 if (PageUptodate(page)) {
1331 unlock_page(page);
1332 goto success;
1333 }
1334
1335 if (!mapping->a_ops->readpage(file, page)) {
1336 wait_on_page_locked(page);
1337 if (PageUptodate(page))
1338 goto success;
1339 }
1340
1341 /*
1342 * Umm, take care of errors if the page isn't up-to-date.
1343 * Try to re-read it _once_. We do this synchronously,
1344 * because there really aren't any performance issues here
1345 * and we need to check for errors.
1346 */
1347 lock_page(page);
1348
1349 /* Somebody truncated the page on us? */
1350 if (!page->mapping) {
1351 unlock_page(page);
1352 page_cache_release(page);
1353 goto retry_all;
1354 }
1355
1356 /* Somebody else successfully read it in? */
1357 if (PageUptodate(page)) {
1358 unlock_page(page);
1359 goto success;
1360 }
1361 ClearPageError(page);
1362 if (!mapping->a_ops->readpage(file, page)) {
1363 wait_on_page_locked(page);
1364 if (PageUptodate(page))
1365 goto success;
1366 }
1367
1368 /*
1369 * Things didn't work out. Return zero to tell the
1370 * mm layer so, possibly freeing the page cache page first.
1371 */
1372 page_cache_release(page);
1373 return NULL;
1374}
1375
1376EXPORT_SYMBOL(filemap_nopage);
1377
1378static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1379 int nonblock)
1380{
1381 struct address_space *mapping = file->f_mapping;
1382 struct page *page;
1383 int error;
1384
1385 /*
1386 * Do we have something in the page cache already?
1387 */
1388retry_find:
1389 page = find_get_page(mapping, pgoff);
1390 if (!page) {
1391 if (nonblock)
1392 return NULL;
1393 goto no_cached_page;
1394 }
1395
1396 /*
1397 * Ok, found a page in the page cache, now we need to check
1398 * that it's up-to-date.
1399 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001400 if (!PageUptodate(page)) {
1401 if (nonblock) {
1402 page_cache_release(page);
1403 return NULL;
1404 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001406 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407
1408success:
1409 /*
1410 * Found the page and have a reference on it.
1411 */
1412 mark_page_accessed(page);
1413 return page;
1414
1415no_cached_page:
1416 error = page_cache_read(file, pgoff);
1417
1418 /*
1419 * The page we want has now been added to the page cache.
1420 * In the unlikely event that someone removed it in the
1421 * meantime, we'll just come back here and read it again.
1422 */
1423 if (error >= 0)
1424 goto retry_find;
1425
1426 /*
1427 * An error return from page_cache_read can result if the
1428 * system is low on memory, or a problem occurs while trying
1429 * to schedule I/O.
1430 */
1431 return NULL;
1432
1433page_not_uptodate:
1434 lock_page(page);
1435
1436 /* Did it get unhashed while we waited for it? */
1437 if (!page->mapping) {
1438 unlock_page(page);
1439 goto err;
1440 }
1441
1442 /* Did somebody else get it up-to-date? */
1443 if (PageUptodate(page)) {
1444 unlock_page(page);
1445 goto success;
1446 }
1447
1448 if (!mapping->a_ops->readpage(file, page)) {
1449 wait_on_page_locked(page);
1450 if (PageUptodate(page))
1451 goto success;
1452 }
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 */
1460 lock_page(page);
1461
1462 /* Somebody truncated the page on us? */
1463 if (!page->mapping) {
1464 unlock_page(page);
1465 goto err;
1466 }
1467 /* Somebody else successfully read it in? */
1468 if (PageUptodate(page)) {
1469 unlock_page(page);
1470 goto success;
1471 }
1472
1473 ClearPageError(page);
1474 if (!mapping->a_ops->readpage(file, page)) {
1475 wait_on_page_locked(page);
1476 if (PageUptodate(page))
1477 goto success;
1478 }
1479
1480 /*
1481 * Things didn't work out. Return zero to tell the
1482 * mm layer so, possibly freeing the page cache page first.
1483 */
1484err:
1485 page_cache_release(page);
1486
1487 return NULL;
1488}
1489
1490int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1491 unsigned long len, pgprot_t prot, unsigned long pgoff,
1492 int nonblock)
1493{
1494 struct file *file = vma->vm_file;
1495 struct address_space *mapping = file->f_mapping;
1496 struct inode *inode = mapping->host;
1497 unsigned long size;
1498 struct mm_struct *mm = vma->vm_mm;
1499 struct page *page;
1500 int err;
1501
1502 if (!nonblock)
1503 force_page_cache_readahead(mapping, vma->vm_file,
1504 pgoff, len >> PAGE_CACHE_SHIFT);
1505
1506repeat:
1507 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1508 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1509 return -EINVAL;
1510
1511 page = filemap_getpage(file, pgoff, nonblock);
1512 if (!page && !nonblock)
1513 return -ENOMEM;
1514 if (page) {
1515 err = install_page(mm, vma, addr, page, prot);
1516 if (err) {
1517 page_cache_release(page);
1518 return err;
1519 }
1520 } else {
1521 err = install_file_pte(mm, vma, addr, pgoff, prot);
1522 if (err)
1523 return err;
1524 }
1525
1526 len -= PAGE_SIZE;
1527 addr += PAGE_SIZE;
1528 pgoff++;
1529 if (len)
1530 goto repeat;
1531
1532 return 0;
1533}
1534
1535struct vm_operations_struct generic_file_vm_ops = {
1536 .nopage = filemap_nopage,
1537 .populate = filemap_populate,
1538};
1539
1540/* This is used for a general mmap of a disk file */
1541
1542int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1543{
1544 struct address_space *mapping = file->f_mapping;
1545
1546 if (!mapping->a_ops->readpage)
1547 return -ENOEXEC;
1548 file_accessed(file);
1549 vma->vm_ops = &generic_file_vm_ops;
1550 return 0;
1551}
1552EXPORT_SYMBOL(filemap_populate);
1553
1554/*
1555 * This is for filesystems which do not implement ->writepage.
1556 */
1557int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1558{
1559 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1560 return -EINVAL;
1561 return generic_file_mmap(file, vma);
1562}
1563#else
1564int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1565{
1566 return -ENOSYS;
1567}
1568int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1569{
1570 return -ENOSYS;
1571}
1572#endif /* CONFIG_MMU */
1573
1574EXPORT_SYMBOL(generic_file_mmap);
1575EXPORT_SYMBOL(generic_file_readonly_mmap);
1576
1577static inline struct page *__read_cache_page(struct address_space *mapping,
1578 unsigned long index,
1579 int (*filler)(void *,struct page*),
1580 void *data)
1581{
1582 struct page *page, *cached_page = NULL;
1583 int err;
1584repeat:
1585 page = find_get_page(mapping, index);
1586 if (!page) {
1587 if (!cached_page) {
1588 cached_page = page_cache_alloc_cold(mapping);
1589 if (!cached_page)
1590 return ERR_PTR(-ENOMEM);
1591 }
1592 err = add_to_page_cache_lru(cached_page, mapping,
1593 index, GFP_KERNEL);
1594 if (err == -EEXIST)
1595 goto repeat;
1596 if (err < 0) {
1597 /* Presumably ENOMEM for radix tree node */
1598 page_cache_release(cached_page);
1599 return ERR_PTR(err);
1600 }
1601 page = cached_page;
1602 cached_page = NULL;
1603 err = filler(data, page);
1604 if (err < 0) {
1605 page_cache_release(page);
1606 page = ERR_PTR(err);
1607 }
1608 }
1609 if (cached_page)
1610 page_cache_release(cached_page);
1611 return page;
1612}
1613
1614/*
1615 * Read into the page cache. If a page already exists,
1616 * and PageUptodate() is not set, try to fill the page.
1617 */
1618struct page *read_cache_page(struct address_space *mapping,
1619 unsigned long index,
1620 int (*filler)(void *,struct page*),
1621 void *data)
1622{
1623 struct page *page;
1624 int err;
1625
1626retry:
1627 page = __read_cache_page(mapping, index, filler, data);
1628 if (IS_ERR(page))
1629 goto out;
1630 mark_page_accessed(page);
1631 if (PageUptodate(page))
1632 goto out;
1633
1634 lock_page(page);
1635 if (!page->mapping) {
1636 unlock_page(page);
1637 page_cache_release(page);
1638 goto retry;
1639 }
1640 if (PageUptodate(page)) {
1641 unlock_page(page);
1642 goto out;
1643 }
1644 err = filler(data, page);
1645 if (err < 0) {
1646 page_cache_release(page);
1647 page = ERR_PTR(err);
1648 }
1649 out:
1650 return page;
1651}
1652
1653EXPORT_SYMBOL(read_cache_page);
1654
1655/*
1656 * If the page was newly created, increment its refcount and add it to the
1657 * caller's lru-buffering pagevec. This function is specifically for
1658 * generic_file_write().
1659 */
1660static inline struct page *
1661__grab_cache_page(struct address_space *mapping, unsigned long index,
1662 struct page **cached_page, struct pagevec *lru_pvec)
1663{
1664 int err;
1665 struct page *page;
1666repeat:
1667 page = find_lock_page(mapping, index);
1668 if (!page) {
1669 if (!*cached_page) {
1670 *cached_page = page_cache_alloc(mapping);
1671 if (!*cached_page)
1672 return NULL;
1673 }
1674 err = add_to_page_cache(*cached_page, mapping,
1675 index, GFP_KERNEL);
1676 if (err == -EEXIST)
1677 goto repeat;
1678 if (err == 0) {
1679 page = *cached_page;
1680 page_cache_get(page);
1681 if (!pagevec_add(lru_pvec, page))
1682 __pagevec_lru_add(lru_pvec);
1683 *cached_page = NULL;
1684 }
1685 }
1686 return page;
1687}
1688
1689/*
1690 * The logic we want is
1691 *
1692 * if suid or (sgid and xgrp)
1693 * remove privs
1694 */
1695int remove_suid(struct dentry *dentry)
1696{
1697 mode_t mode = dentry->d_inode->i_mode;
1698 int kill = 0;
1699 int result = 0;
1700
1701 /* suid always must be killed */
1702 if (unlikely(mode & S_ISUID))
1703 kill = ATTR_KILL_SUID;
1704
1705 /*
1706 * sgid without any exec bits is just a mandatory locking mark; leave
1707 * it alone. If some exec bits are set, it's a real sgid; kill it.
1708 */
1709 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1710 kill |= ATTR_KILL_SGID;
1711
1712 if (unlikely(kill && !capable(CAP_FSETID))) {
1713 struct iattr newattrs;
1714
1715 newattrs.ia_valid = ATTR_FORCE | kill;
1716 result = notify_change(dentry, &newattrs);
1717 }
1718 return result;
1719}
1720EXPORT_SYMBOL(remove_suid);
1721
1722/*
1723 * Copy as much as we can into the page and return the number of bytes which
1724 * were sucessfully copied. If a fault is encountered then clear the page
1725 * out to (offset+bytes) and return the number of bytes which were copied.
1726 */
1727static inline size_t
1728filemap_copy_from_user(struct page *page, unsigned long offset,
1729 const char __user *buf, unsigned bytes)
1730{
1731 char *kaddr;
1732 int left;
1733
1734 kaddr = kmap_atomic(page, KM_USER0);
1735 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
1736 kunmap_atomic(kaddr, KM_USER0);
1737
1738 if (left != 0) {
1739 /* Do it the slow way */
1740 kaddr = kmap(page);
1741 left = __copy_from_user(kaddr + offset, buf, bytes);
1742 kunmap(page);
1743 }
1744 return bytes - left;
1745}
1746
1747static size_t
1748__filemap_copy_from_user_iovec(char *vaddr,
1749 const struct iovec *iov, size_t base, size_t bytes)
1750{
1751 size_t copied = 0, left = 0;
1752
1753 while (bytes) {
1754 char __user *buf = iov->iov_base + base;
1755 int copy = min(bytes, iov->iov_len - base);
1756
1757 base = 0;
1758 left = __copy_from_user_inatomic(vaddr, buf, copy);
1759 copied += copy;
1760 bytes -= copy;
1761 vaddr += copy;
1762 iov++;
1763
1764 if (unlikely(left)) {
1765 /* zero the rest of the target like __copy_from_user */
1766 if (bytes)
1767 memset(vaddr, 0, bytes);
1768 break;
1769 }
1770 }
1771 return copied - left;
1772}
1773
1774/*
1775 * This has the same sideeffects and return value as filemap_copy_from_user().
1776 * The difference is that on a fault we need to memset the remainder of the
1777 * page (out to offset+bytes), to emulate filemap_copy_from_user()'s
1778 * single-segment behaviour.
1779 */
1780static inline size_t
1781filemap_copy_from_user_iovec(struct page *page, unsigned long offset,
1782 const struct iovec *iov, size_t base, size_t bytes)
1783{
1784 char *kaddr;
1785 size_t copied;
1786
1787 kaddr = kmap_atomic(page, KM_USER0);
1788 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1789 base, bytes);
1790 kunmap_atomic(kaddr, KM_USER0);
1791 if (copied != bytes) {
1792 kaddr = kmap(page);
1793 copied = __filemap_copy_from_user_iovec(kaddr + offset, iov,
1794 base, bytes);
1795 kunmap(page);
1796 }
1797 return copied;
1798}
1799
1800static inline void
1801filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
1802{
1803 const struct iovec *iov = *iovp;
1804 size_t base = *basep;
1805
1806 while (bytes) {
1807 int copy = min(bytes, iov->iov_len - base);
1808
1809 bytes -= copy;
1810 base += copy;
1811 if (iov->iov_len == base) {
1812 iov++;
1813 base = 0;
1814 }
1815 }
1816 *iovp = iov;
1817 *basep = base;
1818}
1819
1820/*
1821 * Performs necessary checks before doing a write
1822 *
1823 * Can adjust writing position aor amount of bytes to write.
1824 * Returns appropriate error code that caller should return or
1825 * zero in case that write should be allowed.
1826 */
1827inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1828{
1829 struct inode *inode = file->f_mapping->host;
1830 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1831
1832 if (unlikely(*pos < 0))
1833 return -EINVAL;
1834
1835 if (unlikely(file->f_error)) {
1836 int err = file->f_error;
1837 file->f_error = 0;
1838 return err;
1839 }
1840
1841 if (!isblk) {
1842 /* FIXME: this is for backwards compatibility with 2.4 */
1843 if (file->f_flags & O_APPEND)
1844 *pos = i_size_read(inode);
1845
1846 if (limit != RLIM_INFINITY) {
1847 if (*pos >= limit) {
1848 send_sig(SIGXFSZ, current, 0);
1849 return -EFBIG;
1850 }
1851 if (*count > limit - (typeof(limit))*pos) {
1852 *count = limit - (typeof(limit))*pos;
1853 }
1854 }
1855 }
1856
1857 /*
1858 * LFS rule
1859 */
1860 if (unlikely(*pos + *count > MAX_NON_LFS &&
1861 !(file->f_flags & O_LARGEFILE))) {
1862 if (*pos >= MAX_NON_LFS) {
1863 send_sig(SIGXFSZ, current, 0);
1864 return -EFBIG;
1865 }
1866 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1867 *count = MAX_NON_LFS - (unsigned long)*pos;
1868 }
1869 }
1870
1871 /*
1872 * Are we about to exceed the fs block limit ?
1873 *
1874 * If we have written data it becomes a short write. If we have
1875 * exceeded without writing data we send a signal and return EFBIG.
1876 * Linus frestrict idea will clean these up nicely..
1877 */
1878 if (likely(!isblk)) {
1879 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1880 if (*count || *pos > inode->i_sb->s_maxbytes) {
1881 send_sig(SIGXFSZ, current, 0);
1882 return -EFBIG;
1883 }
1884 /* zero-length writes at ->s_maxbytes are OK */
1885 }
1886
1887 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1888 *count = inode->i_sb->s_maxbytes - *pos;
1889 } else {
1890 loff_t isize;
1891 if (bdev_read_only(I_BDEV(inode)))
1892 return -EPERM;
1893 isize = i_size_read(inode);
1894 if (*pos >= isize) {
1895 if (*count || *pos > isize)
1896 return -ENOSPC;
1897 }
1898
1899 if (*pos + *count > isize)
1900 *count = isize - *pos;
1901 }
1902 return 0;
1903}
1904EXPORT_SYMBOL(generic_write_checks);
1905
1906ssize_t
1907generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1908 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1909 size_t count, size_t ocount)
1910{
1911 struct file *file = iocb->ki_filp;
1912 struct address_space *mapping = file->f_mapping;
1913 struct inode *inode = mapping->host;
1914 ssize_t written;
1915
1916 if (count != ocount)
1917 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1918
1919 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1920 if (written > 0) {
1921 loff_t end = pos + written;
1922 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1923 i_size_write(inode, end);
1924 mark_inode_dirty(inode);
1925 }
1926 *ppos = end;
1927 }
1928
1929 /*
1930 * Sync the fs metadata but not the minor inode changes and
1931 * of course not the data as we did direct DMA for the IO.
1932 * i_sem is held, which protects generic_osync_inode() from
1933 * livelocking.
1934 */
1935 if (written >= 0 && file->f_flags & O_SYNC)
1936 generic_osync_inode(inode, mapping, OSYNC_METADATA);
1937 if (written == count && !is_sync_kiocb(iocb))
1938 written = -EIOCBQUEUED;
1939 return written;
1940}
1941EXPORT_SYMBOL(generic_file_direct_write);
1942
1943ssize_t
1944generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1945 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1946 size_t count, ssize_t written)
1947{
1948 struct file *file = iocb->ki_filp;
1949 struct address_space * mapping = file->f_mapping;
1950 struct address_space_operations *a_ops = mapping->a_ops;
1951 struct inode *inode = mapping->host;
1952 long status = 0;
1953 struct page *page;
1954 struct page *cached_page = NULL;
1955 size_t bytes;
1956 struct pagevec lru_pvec;
1957 const struct iovec *cur_iov = iov; /* current iovec */
1958 size_t iov_base = 0; /* offset in the current iovec */
1959 char __user *buf;
1960
1961 pagevec_init(&lru_pvec, 0);
1962
1963 /*
1964 * handle partial DIO write. Adjust cur_iov if needed.
1965 */
1966 if (likely(nr_segs == 1))
1967 buf = iov->iov_base + written;
1968 else {
1969 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001970 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971 }
1972
1973 do {
1974 unsigned long index;
1975 unsigned long offset;
1976 size_t copied;
1977
1978 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1979 index = pos >> PAGE_CACHE_SHIFT;
1980 bytes = PAGE_CACHE_SIZE - offset;
1981 if (bytes > count)
1982 bytes = count;
1983
1984 /*
1985 * Bring in the user page that we will copy from _first_.
1986 * Otherwise there's a nasty deadlock on copying from the
1987 * same page as we're writing to, without it being marked
1988 * up-to-date.
1989 */
1990 fault_in_pages_readable(buf, bytes);
1991
1992 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1993 if (!page) {
1994 status = -ENOMEM;
1995 break;
1996 }
1997
1998 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1999 if (unlikely(status)) {
2000 loff_t isize = i_size_read(inode);
2001 /*
2002 * prepare_write() may have instantiated a few blocks
2003 * outside i_size. Trim these off again.
2004 */
2005 unlock_page(page);
2006 page_cache_release(page);
2007 if (pos + bytes > isize)
2008 vmtruncate(inode, isize);
2009 break;
2010 }
2011 if (likely(nr_segs == 1))
2012 copied = filemap_copy_from_user(page, offset,
2013 buf, bytes);
2014 else
2015 copied = filemap_copy_from_user_iovec(page, offset,
2016 cur_iov, iov_base, bytes);
2017 flush_dcache_page(page);
2018 status = a_ops->commit_write(file, page, offset, offset+bytes);
2019 if (likely(copied > 0)) {
2020 if (!status)
2021 status = copied;
2022
2023 if (status >= 0) {
2024 written += status;
2025 count -= status;
2026 pos += status;
2027 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002028 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002029 filemap_set_next_iovec(&cur_iov,
2030 &iov_base, status);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002031 buf = cur_iov->iov_base + iov_base;
2032 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 }
2034 }
2035 if (unlikely(copied != bytes))
2036 if (status >= 0)
2037 status = -EFAULT;
2038 unlock_page(page);
2039 mark_page_accessed(page);
2040 page_cache_release(page);
2041 if (status < 0)
2042 break;
2043 balance_dirty_pages_ratelimited(mapping);
2044 cond_resched();
2045 } while (count);
2046 *ppos = pos;
2047
2048 if (cached_page)
2049 page_cache_release(cached_page);
2050
2051 /*
2052 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2053 */
2054 if (likely(status >= 0)) {
2055 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2056 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2057 status = generic_osync_inode(inode, mapping,
2058 OSYNC_METADATA|OSYNC_DATA);
2059 }
2060 }
2061
2062 /*
2063 * If we get here for O_DIRECT writes then we must have fallen through
2064 * to buffered writes (block instantiation inside i_size). So we sync
2065 * the file data here, to try to honour O_DIRECT expectations.
2066 */
2067 if (unlikely(file->f_flags & O_DIRECT) && written)
2068 status = filemap_write_and_wait(mapping);
2069
2070 pagevec_lru_add(&lru_pvec);
2071 return written ? written : status;
2072}
2073EXPORT_SYMBOL(generic_file_buffered_write);
2074
2075ssize_t
2076__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2077 unsigned long nr_segs, loff_t *ppos)
2078{
2079 struct file *file = iocb->ki_filp;
2080 struct address_space * mapping = file->f_mapping;
2081 size_t ocount; /* original count */
2082 size_t count; /* after file limit checks */
2083 struct inode *inode = mapping->host;
2084 unsigned long seg;
2085 loff_t pos;
2086 ssize_t written;
2087 ssize_t err;
2088
2089 ocount = 0;
2090 for (seg = 0; seg < nr_segs; seg++) {
2091 const struct iovec *iv = &iov[seg];
2092
2093 /*
2094 * If any segment has a negative length, or the cumulative
2095 * length ever wraps negative then return -EINVAL.
2096 */
2097 ocount += iv->iov_len;
2098 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2099 return -EINVAL;
2100 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2101 continue;
2102 if (seg == 0)
2103 return -EFAULT;
2104 nr_segs = seg;
2105 ocount -= iv->iov_len; /* This segment is no good */
2106 break;
2107 }
2108
2109 count = ocount;
2110 pos = *ppos;
2111
2112 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2113
2114 /* We can write back this queue in page reclaim */
2115 current->backing_dev_info = mapping->backing_dev_info;
2116 written = 0;
2117
2118 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2119 if (err)
2120 goto out;
2121
2122 if (count == 0)
2123 goto out;
2124
2125 err = remove_suid(file->f_dentry);
2126 if (err)
2127 goto out;
2128
2129 inode_update_time(inode, 1);
2130
2131 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2132 if (unlikely(file->f_flags & O_DIRECT)) {
2133 written = generic_file_direct_write(iocb, iov,
2134 &nr_segs, pos, ppos, count, ocount);
2135 if (written < 0 || written == count)
2136 goto out;
2137 /*
2138 * direct-io write to a hole: fall through to buffered I/O
2139 * for completing the rest of the request.
2140 */
2141 pos += written;
2142 count -= written;
2143 }
2144
2145 written = generic_file_buffered_write(iocb, iov, nr_segs,
2146 pos, ppos, count, written);
2147out:
2148 current->backing_dev_info = NULL;
2149 return written ? written : err;
2150}
2151EXPORT_SYMBOL(generic_file_aio_write_nolock);
2152
2153ssize_t
2154generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2155 unsigned long nr_segs, loff_t *ppos)
2156{
2157 struct file *file = iocb->ki_filp;
2158 struct address_space *mapping = file->f_mapping;
2159 struct inode *inode = mapping->host;
2160 ssize_t ret;
2161 loff_t pos = *ppos;
2162
2163 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2164
2165 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2166 int err;
2167
2168 err = sync_page_range_nolock(inode, mapping, pos, ret);
2169 if (err < 0)
2170 ret = err;
2171 }
2172 return ret;
2173}
2174
2175ssize_t
2176__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2177 unsigned long nr_segs, loff_t *ppos)
2178{
2179 struct kiocb kiocb;
2180 ssize_t ret;
2181
2182 init_sync_kiocb(&kiocb, file);
2183 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2184 if (ret == -EIOCBQUEUED)
2185 ret = wait_on_sync_kiocb(&kiocb);
2186 return ret;
2187}
2188
2189ssize_t
2190generic_file_write_nolock(struct file *file, const struct iovec *iov,
2191 unsigned long nr_segs, loff_t *ppos)
2192{
2193 struct kiocb kiocb;
2194 ssize_t ret;
2195
2196 init_sync_kiocb(&kiocb, file);
2197 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2198 if (-EIOCBQUEUED == ret)
2199 ret = wait_on_sync_kiocb(&kiocb);
2200 return ret;
2201}
2202EXPORT_SYMBOL(generic_file_write_nolock);
2203
2204ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2205 size_t count, loff_t pos)
2206{
2207 struct file *file = iocb->ki_filp;
2208 struct address_space *mapping = file->f_mapping;
2209 struct inode *inode = mapping->host;
2210 ssize_t ret;
2211 struct iovec local_iov = { .iov_base = (void __user *)buf,
2212 .iov_len = count };
2213
2214 BUG_ON(iocb->ki_pos != pos);
2215
2216 down(&inode->i_sem);
2217 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2218 &iocb->ki_pos);
2219 up(&inode->i_sem);
2220
2221 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2222 ssize_t err;
2223
2224 err = sync_page_range(inode, mapping, pos, ret);
2225 if (err < 0)
2226 ret = err;
2227 }
2228 return ret;
2229}
2230EXPORT_SYMBOL(generic_file_aio_write);
2231
2232ssize_t generic_file_write(struct file *file, const char __user *buf,
2233 size_t count, loff_t *ppos)
2234{
2235 struct address_space *mapping = file->f_mapping;
2236 struct inode *inode = mapping->host;
2237 ssize_t ret;
2238 struct iovec local_iov = { .iov_base = (void __user *)buf,
2239 .iov_len = count };
2240
2241 down(&inode->i_sem);
2242 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2243 up(&inode->i_sem);
2244
2245 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2246 ssize_t err;
2247
2248 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2249 if (err < 0)
2250 ret = err;
2251 }
2252 return ret;
2253}
2254EXPORT_SYMBOL(generic_file_write);
2255
2256ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2257 unsigned long nr_segs, loff_t *ppos)
2258{
2259 struct kiocb kiocb;
2260 ssize_t ret;
2261
2262 init_sync_kiocb(&kiocb, filp);
2263 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2264 if (-EIOCBQUEUED == ret)
2265 ret = wait_on_sync_kiocb(&kiocb);
2266 return ret;
2267}
2268EXPORT_SYMBOL(generic_file_readv);
2269
2270ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2271 unsigned long nr_segs, loff_t *ppos)
2272{
2273 struct address_space *mapping = file->f_mapping;
2274 struct inode *inode = mapping->host;
2275 ssize_t ret;
2276
2277 down(&inode->i_sem);
2278 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2279 up(&inode->i_sem);
2280
2281 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2282 int err;
2283
2284 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2285 if (err < 0)
2286 ret = err;
2287 }
2288 return ret;
2289}
2290EXPORT_SYMBOL(generic_file_writev);
2291
2292/*
2293 * Called under i_sem for writes to S_ISREG files. Returns -EIO if something
2294 * went wrong during pagecache shootdown.
2295 */
2296ssize_t
2297generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2298 loff_t offset, unsigned long nr_segs)
2299{
2300 struct file *file = iocb->ki_filp;
2301 struct address_space *mapping = file->f_mapping;
2302 ssize_t retval;
2303 size_t write_len = 0;
2304
2305 /*
2306 * If it's a write, unmap all mmappings of the file up-front. This
2307 * will cause any pte dirty bits to be propagated into the pageframes
2308 * for the subsequent filemap_write_and_wait().
2309 */
2310 if (rw == WRITE) {
2311 write_len = iov_length(iov, nr_segs);
2312 if (mapping_mapped(mapping))
2313 unmap_mapping_range(mapping, offset, write_len, 0);
2314 }
2315
2316 retval = filemap_write_and_wait(mapping);
2317 if (retval == 0) {
2318 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2319 offset, nr_segs);
2320 if (rw == WRITE && mapping->nrpages) {
2321 pgoff_t end = (offset + write_len - 1)
2322 >> PAGE_CACHE_SHIFT;
2323 int err = invalidate_inode_pages2_range(mapping,
2324 offset >> PAGE_CACHE_SHIFT, end);
2325 if (err)
2326 retval = err;
2327 }
2328 }
2329 return retval;
2330}
2331EXPORT_SYMBOL_GPL(generic_file_direct_IO);