blob: 036599d1177e3e8098f874e79785d538e3085e9a [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>
Carsten Otteceffc072005-06-23 22:05:25 -070031#include "filemap.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070032/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 * FIXME: remove all knowledge of the buffer layer from the core VM
34 */
35#include <linux/buffer_head.h> /* for generic_osync_inode */
36
37#include <asm/uaccess.h>
38#include <asm/mman.h>
39
Adrian Bunk5ce78522005-09-10 00:26:28 -070040static ssize_t
41generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
42 loff_t offset, unsigned long nr_segs);
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044/*
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)
Hugh Dickins5d337b92005-09-03 15:54:41 -070061 * ->swap_lock (exclusive_swap_page, others)
62 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 *
64 * ->i_sem
65 * ->i_mmap_lock (truncate->unmap_mapping_range)
66 *
67 * ->mmap_sem
68 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070069 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
71 *
72 * ->mmap_sem
73 * ->lock_page (access_process_vm)
74 *
75 * ->mmap_sem
76 * ->i_sem (msync)
77 *
78 * ->i_sem
79 * ->i_alloc_sem (various)
80 *
81 * ->inode_lock
82 * ->sb_lock (fs/fs-writeback.c)
83 * ->mapping->tree_lock (__sync_single_inode)
84 *
85 * ->i_mmap_lock
86 * ->anon_vma.lock (vma_adjust)
87 *
88 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070089 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070091 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070092 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 * ->private_lock (try_to_unmap_one)
94 * ->tree_lock (try_to_unmap_one)
95 * ->zone.lru_lock (follow_page->mark_page_accessed)
96 * ->private_lock (page_remove_rmap->set_page_dirty)
97 * ->tree_lock (page_remove_rmap->set_page_dirty)
98 * ->inode_lock (page_remove_rmap->set_page_dirty)
99 * ->inode_lock (zap_pte_range->set_page_dirty)
100 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
101 *
102 * ->task->proc_lock
103 * ->dcache_lock (proc_pid_lookup)
104 */
105
106/*
107 * Remove a page from the page cache and free it. Caller has to make
108 * sure the page is locked and that nobody else uses it - or that usage
109 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
110 */
111void __remove_from_page_cache(struct page *page)
112{
113 struct address_space *mapping = page->mapping;
114
115 radix_tree_delete(&mapping->page_tree, page->index);
116 page->mapping = NULL;
117 mapping->nrpages--;
118 pagecache_acct(-1);
119}
120
121void remove_from_page_cache(struct page *page)
122{
123 struct address_space *mapping = page->mapping;
124
Matt Mackallcd7619d2005-05-01 08:59:01 -0700125 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
127 write_lock_irq(&mapping->tree_lock);
128 __remove_from_page_cache(page);
129 write_unlock_irq(&mapping->tree_lock);
130}
131
132static int sync_page(void *word)
133{
134 struct address_space *mapping;
135 struct page *page;
136
137 page = container_of((page_flags_t *)word, struct page, flags);
138
139 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700140 * page_mapping() is being called without PG_locked held.
141 * Some knowledge of the state and use of the page is used to
142 * reduce the requirements down to a memory barrier.
143 * The danger here is of a stale page_mapping() return value
144 * indicating a struct address_space different from the one it's
145 * associated with when it is associated with one.
146 * After smp_mb(), it's either the correct page_mapping() for
147 * the page, or an old page_mapping() and the page's own
148 * page_mapping() has gone NULL.
149 * The ->sync_page() address_space operation must tolerate
150 * page_mapping() going NULL. By an amazing coincidence,
151 * this comes about because none of the users of the page
152 * in the ->sync_page() methods make essential use of the
153 * page_mapping(), merely passing the page down to the backing
154 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700155 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700156 * of interest. When page_mapping() does go NULL, the entire
157 * call stack gracefully ignores the page and returns.
158 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 */
160 smp_mb();
161 mapping = page_mapping(page);
162 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
163 mapping->a_ops->sync_page(page);
164 io_schedule();
165 return 0;
166}
167
168/**
169 * filemap_fdatawrite_range - start writeback against all of a mapping's
170 * dirty pages that lie within the byte offsets <start, end>
Martin Waitz67be2dd2005-05-01 08:59:26 -0700171 * @mapping: address space structure to write
172 * @start: offset in bytes where the range starts
173 * @end: offset in bytes where the range ends
174 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 *
176 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
177 * opposed to a regular memory * cleansing writeback. The difference between
178 * these two operations is that if a dirty page/buffer is encountered, it must
179 * be waited upon, and not just skipped over.
180 */
181static int __filemap_fdatawrite_range(struct address_space *mapping,
182 loff_t start, loff_t end, int sync_mode)
183{
184 int ret;
185 struct writeback_control wbc = {
186 .sync_mode = sync_mode,
187 .nr_to_write = mapping->nrpages * 2,
188 .start = start,
189 .end = end,
190 };
191
192 if (!mapping_cap_writeback_dirty(mapping))
193 return 0;
194
195 ret = do_writepages(mapping, &wbc);
196 return ret;
197}
198
199static inline int __filemap_fdatawrite(struct address_space *mapping,
200 int sync_mode)
201{
202 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
203}
204
205int filemap_fdatawrite(struct address_space *mapping)
206{
207 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
208}
209EXPORT_SYMBOL(filemap_fdatawrite);
210
211static int filemap_fdatawrite_range(struct address_space *mapping,
212 loff_t start, loff_t end)
213{
214 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
215}
216
217/*
218 * This is a mostly non-blocking flush. Not suitable for data-integrity
219 * purposes - I/O may not be started against all dirty pages.
220 */
221int filemap_flush(struct address_space *mapping)
222{
223 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
224}
225EXPORT_SYMBOL(filemap_flush);
226
227/*
228 * Wait for writeback to complete against pages indexed by start->end
229 * inclusive
230 */
231static int wait_on_page_writeback_range(struct address_space *mapping,
232 pgoff_t start, pgoff_t end)
233{
234 struct pagevec pvec;
235 int nr_pages;
236 int ret = 0;
237 pgoff_t index;
238
239 if (end < start)
240 return 0;
241
242 pagevec_init(&pvec, 0);
243 index = start;
244 while ((index <= end) &&
245 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
246 PAGECACHE_TAG_WRITEBACK,
247 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
248 unsigned i;
249
250 for (i = 0; i < nr_pages; i++) {
251 struct page *page = pvec.pages[i];
252
253 /* until radix tree lookup accepts end_index */
254 if (page->index > end)
255 continue;
256
257 wait_on_page_writeback(page);
258 if (PageError(page))
259 ret = -EIO;
260 }
261 pagevec_release(&pvec);
262 cond_resched();
263 }
264
265 /* Check for outstanding write errors */
266 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
267 ret = -ENOSPC;
268 if (test_and_clear_bit(AS_EIO, &mapping->flags))
269 ret = -EIO;
270
271 return ret;
272}
273
274/*
275 * Write and wait upon all the pages in the passed range. This is a "data
276 * integrity" operation. It waits upon in-flight writeout before starting and
277 * waiting upon new writeout. If there was an IO error, return it.
278 *
279 * We need to re-take i_sem during the generic_osync_inode list walk because
280 * it is otherwise livelockable.
281 */
282int sync_page_range(struct inode *inode, struct address_space *mapping,
283 loff_t pos, size_t count)
284{
285 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
286 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
287 int ret;
288
289 if (!mapping_cap_writeback_dirty(mapping) || !count)
290 return 0;
291 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
292 if (ret == 0) {
293 down(&inode->i_sem);
294 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
295 up(&inode->i_sem);
296 }
297 if (ret == 0)
298 ret = wait_on_page_writeback_range(mapping, start, end);
299 return ret;
300}
301EXPORT_SYMBOL(sync_page_range);
302
303/*
304 * Note: Holding i_sem across sync_page_range_nolock is not a good idea
305 * as it forces O_SYNC writers to different parts of the same file
306 * to be serialised right until io completion.
307 */
Adrian Bunk5ce78522005-09-10 00:26:28 -0700308static int sync_page_range_nolock(struct inode *inode,
309 struct address_space *mapping,
310 loff_t pos, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311{
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}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325
326/**
327 * filemap_fdatawait - walk the list of under-writeback pages of the given
328 * address space and wait for all of them.
329 *
330 * @mapping: address space structure to wait for
331 */
332int filemap_fdatawait(struct address_space *mapping)
333{
334 loff_t i_size = i_size_read(mapping->host);
335
336 if (i_size == 0)
337 return 0;
338
339 return wait_on_page_writeback_range(mapping, 0,
340 (i_size - 1) >> PAGE_CACHE_SHIFT);
341}
342EXPORT_SYMBOL(filemap_fdatawait);
343
344int filemap_write_and_wait(struct address_space *mapping)
345{
346 int retval = 0;
347
348 if (mapping->nrpages) {
349 retval = filemap_fdatawrite(mapping);
350 if (retval == 0)
351 retval = filemap_fdatawait(mapping);
352 }
353 return retval;
354}
355
356int filemap_write_and_wait_range(struct address_space *mapping,
357 loff_t lstart, loff_t lend)
358{
359 int retval = 0;
360
361 if (mapping->nrpages) {
362 retval = __filemap_fdatawrite_range(mapping, lstart, lend,
363 WB_SYNC_ALL);
364 if (retval == 0)
365 retval = wait_on_page_writeback_range(mapping,
366 lstart >> PAGE_CACHE_SHIFT,
367 lend >> PAGE_CACHE_SHIFT);
368 }
369 return retval;
370}
371
372/*
373 * This function is used to add newly allocated pagecache pages:
374 * the page is new, so we can just run SetPageLocked() against it.
375 * The other page state flags were set by rmqueue().
376 *
377 * This function does not add the page to the LRU. The caller must do that.
378 */
379int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400380 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381{
382 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
383
384 if (error == 0) {
385 write_lock_irq(&mapping->tree_lock);
386 error = radix_tree_insert(&mapping->page_tree, offset, page);
387 if (!error) {
388 page_cache_get(page);
389 SetPageLocked(page);
390 page->mapping = mapping;
391 page->index = offset;
392 mapping->nrpages++;
393 pagecache_acct(1);
394 }
395 write_unlock_irq(&mapping->tree_lock);
396 radix_tree_preload_end();
397 }
398 return error;
399}
400
401EXPORT_SYMBOL(add_to_page_cache);
402
403int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400404 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405{
406 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
407 if (ret == 0)
408 lru_cache_add(page);
409 return ret;
410}
411
412/*
413 * In order to wait for pages to become available there must be
414 * waitqueues associated with pages. By using a hash table of
415 * waitqueues where the bucket discipline is to maintain all
416 * waiters on the same queue and wake all when any of the pages
417 * become available, and for the woken contexts to check to be
418 * sure the appropriate page became available, this saves space
419 * at a cost of "thundering herd" phenomena during rare hash
420 * collisions.
421 */
422static wait_queue_head_t *page_waitqueue(struct page *page)
423{
424 const struct zone *zone = page_zone(page);
425
426 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
427}
428
429static inline void wake_up_page(struct page *page, int bit)
430{
431 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
432}
433
434void fastcall wait_on_page_bit(struct page *page, int bit_nr)
435{
436 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
437
438 if (test_bit(bit_nr, &page->flags))
439 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
440 TASK_UNINTERRUPTIBLE);
441}
442EXPORT_SYMBOL(wait_on_page_bit);
443
444/**
445 * unlock_page() - unlock a locked page
446 *
447 * @page: the page
448 *
449 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
450 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
451 * mechananism between PageLocked pages and PageWriteback pages is shared.
452 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
453 *
454 * The first mb is necessary to safely close the critical section opened by the
455 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
456 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
457 * parallel wait_on_page_locked()).
458 */
459void fastcall unlock_page(struct page *page)
460{
461 smp_mb__before_clear_bit();
462 if (!TestClearPageLocked(page))
463 BUG();
464 smp_mb__after_clear_bit();
465 wake_up_page(page, PG_locked);
466}
467EXPORT_SYMBOL(unlock_page);
468
469/*
470 * End writeback against a page.
471 */
472void end_page_writeback(struct page *page)
473{
474 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
475 if (!test_clear_page_writeback(page))
476 BUG();
477 }
478 smp_mb__after_clear_bit();
479 wake_up_page(page, PG_writeback);
480}
481EXPORT_SYMBOL(end_page_writeback);
482
483/*
484 * Get a lock on the page, assuming we need to sleep to get it.
485 *
486 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
487 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
488 * chances are that on the second loop, the block layer's plug list is empty,
489 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
490 */
491void fastcall __lock_page(struct page *page)
492{
493 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
494
495 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
496 TASK_UNINTERRUPTIBLE);
497}
498EXPORT_SYMBOL(__lock_page);
499
500/*
501 * a rather lightweight function, finding and getting a reference to a
502 * hashed page atomically.
503 */
504struct page * find_get_page(struct address_space *mapping, unsigned long offset)
505{
506 struct page *page;
507
508 read_lock_irq(&mapping->tree_lock);
509 page = radix_tree_lookup(&mapping->page_tree, offset);
510 if (page)
511 page_cache_get(page);
512 read_unlock_irq(&mapping->tree_lock);
513 return page;
514}
515
516EXPORT_SYMBOL(find_get_page);
517
518/*
519 * Same as above, but trylock it instead of incrementing the count.
520 */
521struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
522{
523 struct page *page;
524
525 read_lock_irq(&mapping->tree_lock);
526 page = radix_tree_lookup(&mapping->page_tree, offset);
527 if (page && TestSetPageLocked(page))
528 page = NULL;
529 read_unlock_irq(&mapping->tree_lock);
530 return page;
531}
532
533EXPORT_SYMBOL(find_trylock_page);
534
535/**
536 * find_lock_page - locate, pin and lock a pagecache page
537 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700538 * @mapping: the address_space to search
539 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 *
541 * Locates the desired pagecache page, locks it, increments its reference
542 * count and returns its address.
543 *
544 * Returns zero if the page was not present. find_lock_page() may sleep.
545 */
546struct page *find_lock_page(struct address_space *mapping,
547 unsigned long offset)
548{
549 struct page *page;
550
551 read_lock_irq(&mapping->tree_lock);
552repeat:
553 page = radix_tree_lookup(&mapping->page_tree, offset);
554 if (page) {
555 page_cache_get(page);
556 if (TestSetPageLocked(page)) {
557 read_unlock_irq(&mapping->tree_lock);
558 lock_page(page);
559 read_lock_irq(&mapping->tree_lock);
560
561 /* Has the page been truncated while we slept? */
562 if (page->mapping != mapping || page->index != offset) {
563 unlock_page(page);
564 page_cache_release(page);
565 goto repeat;
566 }
567 }
568 }
569 read_unlock_irq(&mapping->tree_lock);
570 return page;
571}
572
573EXPORT_SYMBOL(find_lock_page);
574
575/**
576 * find_or_create_page - locate or add a pagecache page
577 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700578 * @mapping: the page's address_space
579 * @index: the page's index into the mapping
580 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 *
582 * Locates a page in the pagecache. If the page is not present, a new page
583 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
584 * LRU list. The returned page is locked and has its reference count
585 * incremented.
586 *
587 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
588 * allocation!
589 *
590 * find_or_create_page() returns the desired page's address, or zero on
591 * memory exhaustion.
592 */
593struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400594 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595{
596 struct page *page, *cached_page = NULL;
597 int err;
598repeat:
599 page = find_lock_page(mapping, index);
600 if (!page) {
601 if (!cached_page) {
602 cached_page = alloc_page(gfp_mask);
603 if (!cached_page)
604 return NULL;
605 }
606 err = add_to_page_cache_lru(cached_page, mapping,
607 index, gfp_mask);
608 if (!err) {
609 page = cached_page;
610 cached_page = NULL;
611 } else if (err == -EEXIST)
612 goto repeat;
613 }
614 if (cached_page)
615 page_cache_release(cached_page);
616 return page;
617}
618
619EXPORT_SYMBOL(find_or_create_page);
620
621/**
622 * find_get_pages - gang pagecache lookup
623 * @mapping: The address_space to search
624 * @start: The starting page index
625 * @nr_pages: The maximum number of pages
626 * @pages: Where the resulting pages are placed
627 *
628 * find_get_pages() will search for and return a group of up to
629 * @nr_pages pages in the mapping. The pages are placed at @pages.
630 * find_get_pages() takes a reference against the returned pages.
631 *
632 * The search returns a group of mapping-contiguous pages with ascending
633 * indexes. There may be holes in the indices due to not-present pages.
634 *
635 * find_get_pages() returns the number of pages which were found.
636 */
637unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
638 unsigned int nr_pages, struct page **pages)
639{
640 unsigned int i;
641 unsigned int ret;
642
643 read_lock_irq(&mapping->tree_lock);
644 ret = radix_tree_gang_lookup(&mapping->page_tree,
645 (void **)pages, start, nr_pages);
646 for (i = 0; i < ret; i++)
647 page_cache_get(pages[i]);
648 read_unlock_irq(&mapping->tree_lock);
649 return ret;
650}
651
652/*
653 * Like find_get_pages, except we only return pages which are tagged with
654 * `tag'. We update *index to index the next page for the traversal.
655 */
656unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
657 int tag, unsigned int nr_pages, struct page **pages)
658{
659 unsigned int i;
660 unsigned int ret;
661
662 read_lock_irq(&mapping->tree_lock);
663 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
664 (void **)pages, *index, nr_pages, tag);
665 for (i = 0; i < ret; i++)
666 page_cache_get(pages[i]);
667 if (ret)
668 *index = pages[ret - 1]->index + 1;
669 read_unlock_irq(&mapping->tree_lock);
670 return ret;
671}
672
673/*
674 * Same as grab_cache_page, but do not wait if the page is unavailable.
675 * This is intended for speculative data generators, where the data can
676 * be regenerated if the page couldn't be grabbed. This routine should
677 * be safe to call while holding the lock for another page.
678 *
679 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
680 * and deadlock against the caller's locked page.
681 */
682struct page *
683grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
684{
685 struct page *page = find_get_page(mapping, index);
Al Viro6daa0e22005-10-21 03:18:50 -0400686 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687
688 if (page) {
689 if (!TestSetPageLocked(page))
690 return page;
691 page_cache_release(page);
692 return NULL;
693 }
694 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
695 page = alloc_pages(gfp_mask, 0);
696 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
697 page_cache_release(page);
698 page = NULL;
699 }
700 return page;
701}
702
703EXPORT_SYMBOL(grab_cache_page_nowait);
704
705/*
706 * This is a generic file read routine, and uses the
707 * mapping->a_ops->readpage() function for the actual low-level
708 * stuff.
709 *
710 * This is really ugly. But the goto's actually try to clarify some
711 * of the logic when it comes to error handling etc.
712 *
713 * Note the struct file* is only passed for the use of readpage. It may be
714 * NULL.
715 */
716void do_generic_mapping_read(struct address_space *mapping,
717 struct file_ra_state *_ra,
718 struct file *filp,
719 loff_t *ppos,
720 read_descriptor_t *desc,
721 read_actor_t actor)
722{
723 struct inode *inode = mapping->host;
724 unsigned long index;
725 unsigned long end_index;
726 unsigned long offset;
727 unsigned long last_index;
728 unsigned long next_index;
729 unsigned long prev_index;
730 loff_t isize;
731 struct page *cached_page;
732 int error;
733 struct file_ra_state ra = *_ra;
734
735 cached_page = NULL;
736 index = *ppos >> PAGE_CACHE_SHIFT;
737 next_index = index;
738 prev_index = ra.prev_page;
739 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
740 offset = *ppos & ~PAGE_CACHE_MASK;
741
742 isize = i_size_read(inode);
743 if (!isize)
744 goto out;
745
746 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
747 for (;;) {
748 struct page *page;
749 unsigned long nr, ret;
750
751 /* nr is the maximum number of bytes to copy from this page */
752 nr = PAGE_CACHE_SIZE;
753 if (index >= end_index) {
754 if (index > end_index)
755 goto out;
756 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
757 if (nr <= offset) {
758 goto out;
759 }
760 }
761 nr = nr - offset;
762
763 cond_resched();
764 if (index == next_index)
765 next_index = page_cache_readahead(mapping, &ra, filp,
766 index, last_index - index);
767
768find_page:
769 page = find_get_page(mapping, index);
770 if (unlikely(page == NULL)) {
771 handle_ra_miss(mapping, &ra, index);
772 goto no_cached_page;
773 }
774 if (!PageUptodate(page))
775 goto page_not_up_to_date;
776page_ok:
777
778 /* If users can be writing to this page using arbitrary
779 * virtual addresses, take care about potential aliasing
780 * before reading the page on the kernel side.
781 */
782 if (mapping_writably_mapped(mapping))
783 flush_dcache_page(page);
784
785 /*
786 * When (part of) the same page is read multiple times
787 * in succession, only mark it as accessed the first time.
788 */
789 if (prev_index != index)
790 mark_page_accessed(page);
791 prev_index = index;
792
793 /*
794 * Ok, we have the page, and it's up-to-date, so
795 * now we can copy it to user space...
796 *
797 * The actor routine returns how many bytes were actually used..
798 * NOTE! This may not be the same as how much of a user buffer
799 * we filled up (we may be padding etc), so we can only update
800 * "pos" here (the actor routine has to update the user buffer
801 * pointers and the remaining count).
802 */
803 ret = actor(desc, page, offset, nr);
804 offset += ret;
805 index += offset >> PAGE_CACHE_SHIFT;
806 offset &= ~PAGE_CACHE_MASK;
807
808 page_cache_release(page);
809 if (ret == nr && desc->count)
810 continue;
811 goto out;
812
813page_not_up_to_date:
814 /* Get exclusive access to the page ... */
815 lock_page(page);
816
817 /* Did it get unhashed before we got the lock? */
818 if (!page->mapping) {
819 unlock_page(page);
820 page_cache_release(page);
821 continue;
822 }
823
824 /* Did somebody else fill it already? */
825 if (PageUptodate(page)) {
826 unlock_page(page);
827 goto page_ok;
828 }
829
830readpage:
831 /* Start the actual read. The read will unlock the page. */
832 error = mapping->a_ops->readpage(filp, page);
833
834 if (unlikely(error))
835 goto readpage_error;
836
837 if (!PageUptodate(page)) {
838 lock_page(page);
839 if (!PageUptodate(page)) {
840 if (page->mapping == NULL) {
841 /*
842 * invalidate_inode_pages got it
843 */
844 unlock_page(page);
845 page_cache_release(page);
846 goto find_page;
847 }
848 unlock_page(page);
849 error = -EIO;
850 goto readpage_error;
851 }
852 unlock_page(page);
853 }
854
855 /*
856 * i_size must be checked after we have done ->readpage.
857 *
858 * Checking i_size after the readpage allows us to calculate
859 * the correct value for "nr", which means the zero-filled
860 * part of the page is not copied back to userspace (unless
861 * another truncate extends the file - this is desired though).
862 */
863 isize = i_size_read(inode);
864 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
865 if (unlikely(!isize || index > end_index)) {
866 page_cache_release(page);
867 goto out;
868 }
869
870 /* nr is the maximum number of bytes to copy from this page */
871 nr = PAGE_CACHE_SIZE;
872 if (index == end_index) {
873 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
874 if (nr <= offset) {
875 page_cache_release(page);
876 goto out;
877 }
878 }
879 nr = nr - offset;
880 goto page_ok;
881
882readpage_error:
883 /* UHHUH! A synchronous read error occurred. Report it */
884 desc->error = error;
885 page_cache_release(page);
886 goto out;
887
888no_cached_page:
889 /*
890 * Ok, it wasn't cached, so we need to create a new
891 * page..
892 */
893 if (!cached_page) {
894 cached_page = page_cache_alloc_cold(mapping);
895 if (!cached_page) {
896 desc->error = -ENOMEM;
897 goto out;
898 }
899 }
900 error = add_to_page_cache_lru(cached_page, mapping,
901 index, GFP_KERNEL);
902 if (error) {
903 if (error == -EEXIST)
904 goto find_page;
905 desc->error = error;
906 goto out;
907 }
908 page = cached_page;
909 cached_page = NULL;
910 goto readpage;
911 }
912
913out:
914 *_ra = ra;
915
916 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
917 if (cached_page)
918 page_cache_release(cached_page);
919 if (filp)
920 file_accessed(filp);
921}
922
923EXPORT_SYMBOL(do_generic_mapping_read);
924
925int file_read_actor(read_descriptor_t *desc, struct page *page,
926 unsigned long offset, unsigned long size)
927{
928 char *kaddr;
929 unsigned long left, count = desc->count;
930
931 if (size > count)
932 size = count;
933
934 /*
935 * Faults on the destination of a read are common, so do it before
936 * taking the kmap.
937 */
938 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
939 kaddr = kmap_atomic(page, KM_USER0);
940 left = __copy_to_user_inatomic(desc->arg.buf,
941 kaddr + offset, size);
942 kunmap_atomic(kaddr, KM_USER0);
943 if (left == 0)
944 goto success;
945 }
946
947 /* Do it the slow way */
948 kaddr = kmap(page);
949 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
950 kunmap(page);
951
952 if (left) {
953 size -= left;
954 desc->error = -EFAULT;
955 }
956success:
957 desc->count = count - size;
958 desc->written += size;
959 desc->arg.buf += size;
960 return size;
961}
962
963/*
964 * This is the "read()" routine for all filesystems
965 * that can use the page cache directly.
966 */
967ssize_t
968__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
969 unsigned long nr_segs, loff_t *ppos)
970{
971 struct file *filp = iocb->ki_filp;
972 ssize_t retval;
973 unsigned long seg;
974 size_t count;
975
976 count = 0;
977 for (seg = 0; seg < nr_segs; seg++) {
978 const struct iovec *iv = &iov[seg];
979
980 /*
981 * If any segment has a negative length, or the cumulative
982 * length ever wraps negative then return -EINVAL.
983 */
984 count += iv->iov_len;
985 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
986 return -EINVAL;
987 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
988 continue;
989 if (seg == 0)
990 return -EFAULT;
991 nr_segs = seg;
992 count -= iv->iov_len; /* This segment is no good */
993 break;
994 }
995
996 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
997 if (filp->f_flags & O_DIRECT) {
998 loff_t pos = *ppos, size;
999 struct address_space *mapping;
1000 struct inode *inode;
1001
1002 mapping = filp->f_mapping;
1003 inode = mapping->host;
1004 retval = 0;
1005 if (!count)
1006 goto out; /* skip atime */
1007 size = i_size_read(inode);
1008 if (pos < size) {
1009 retval = generic_file_direct_IO(READ, iocb,
1010 iov, pos, nr_segs);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001011 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 retval = -EIOCBQUEUED;
1013 if (retval > 0)
1014 *ppos = pos + retval;
1015 }
1016 file_accessed(filp);
1017 goto out;
1018 }
1019
1020 retval = 0;
1021 if (count) {
1022 for (seg = 0; seg < nr_segs; seg++) {
1023 read_descriptor_t desc;
1024
1025 desc.written = 0;
1026 desc.arg.buf = iov[seg].iov_base;
1027 desc.count = iov[seg].iov_len;
1028 if (desc.count == 0)
1029 continue;
1030 desc.error = 0;
1031 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1032 retval += desc.written;
1033 if (!retval) {
1034 retval = desc.error;
1035 break;
1036 }
1037 }
1038 }
1039out:
1040 return retval;
1041}
1042
1043EXPORT_SYMBOL(__generic_file_aio_read);
1044
1045ssize_t
1046generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1047{
1048 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1049
1050 BUG_ON(iocb->ki_pos != pos);
1051 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1052}
1053
1054EXPORT_SYMBOL(generic_file_aio_read);
1055
1056ssize_t
1057generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1058{
1059 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1060 struct kiocb kiocb;
1061 ssize_t ret;
1062
1063 init_sync_kiocb(&kiocb, filp);
1064 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1065 if (-EIOCBQUEUED == ret)
1066 ret = wait_on_sync_kiocb(&kiocb);
1067 return ret;
1068}
1069
1070EXPORT_SYMBOL(generic_file_read);
1071
1072int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1073{
1074 ssize_t written;
1075 unsigned long count = desc->count;
1076 struct file *file = desc->arg.data;
1077
1078 if (size > count)
1079 size = count;
1080
1081 written = file->f_op->sendpage(file, page, offset,
1082 size, &file->f_pos, size<count);
1083 if (written < 0) {
1084 desc->error = written;
1085 written = 0;
1086 }
1087 desc->count = count - written;
1088 desc->written += written;
1089 return written;
1090}
1091
1092ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1093 size_t count, read_actor_t actor, void *target)
1094{
1095 read_descriptor_t desc;
1096
1097 if (!count)
1098 return 0;
1099
1100 desc.written = 0;
1101 desc.count = count;
1102 desc.arg.data = target;
1103 desc.error = 0;
1104
1105 do_generic_file_read(in_file, ppos, &desc, actor);
1106 if (desc.written)
1107 return desc.written;
1108 return desc.error;
1109}
1110
1111EXPORT_SYMBOL(generic_file_sendfile);
1112
1113static ssize_t
1114do_readahead(struct address_space *mapping, struct file *filp,
1115 unsigned long index, unsigned long nr)
1116{
1117 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1118 return -EINVAL;
1119
1120 force_page_cache_readahead(mapping, filp, index,
1121 max_sane_readahead(nr));
1122 return 0;
1123}
1124
1125asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1126{
1127 ssize_t ret;
1128 struct file *file;
1129
1130 ret = -EBADF;
1131 file = fget(fd);
1132 if (file) {
1133 if (file->f_mode & FMODE_READ) {
1134 struct address_space *mapping = file->f_mapping;
1135 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1136 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1137 unsigned long len = end - start + 1;
1138 ret = do_readahead(mapping, file, start, len);
1139 }
1140 fput(file);
1141 }
1142 return ret;
1143}
1144
1145#ifdef CONFIG_MMU
1146/*
1147 * This adds the requested page to the page cache if it isn't already there,
1148 * and schedules an I/O to read in its contents from disk.
1149 */
1150static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1151static int fastcall page_cache_read(struct file * file, unsigned long offset)
1152{
1153 struct address_space *mapping = file->f_mapping;
1154 struct page *page;
1155 int error;
1156
1157 page = page_cache_alloc_cold(mapping);
1158 if (!page)
1159 return -ENOMEM;
1160
1161 error = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1162 if (!error) {
1163 error = mapping->a_ops->readpage(file, page);
1164 page_cache_release(page);
1165 return error;
1166 }
1167
1168 /*
1169 * We arrive here in the unlikely event that someone
1170 * raced with us and added our page to the cache first
1171 * or we are out of memory for radix-tree nodes.
1172 */
1173 page_cache_release(page);
1174 return error == -EEXIST ? 0 : error;
1175}
1176
1177#define MMAP_LOTSAMISS (100)
1178
1179/*
1180 * filemap_nopage() is invoked via the vma operations vector for a
1181 * mapped memory region to read in file data during a page fault.
1182 *
1183 * The goto's are kind of ugly, but this streamlines the normal case of having
1184 * it in the page cache, and handles the special cases reasonably without
1185 * having a lot of duplicated code.
1186 */
1187struct page *filemap_nopage(struct vm_area_struct *area,
1188 unsigned long address, int *type)
1189{
1190 int error;
1191 struct file *file = area->vm_file;
1192 struct address_space *mapping = file->f_mapping;
1193 struct file_ra_state *ra = &file->f_ra;
1194 struct inode *inode = mapping->host;
1195 struct page *page;
1196 unsigned long size, pgoff;
1197 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1198
1199 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1200
1201retry_all:
1202 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1203 if (pgoff >= size)
1204 goto outside_data_content;
1205
1206 /* If we don't want any read-ahead, don't bother */
1207 if (VM_RandomReadHint(area))
1208 goto no_cached_page;
1209
1210 /*
1211 * The readahead code wants to be told about each and every page
1212 * so it can build and shrink its windows appropriately
1213 *
1214 * For sequential accesses, we use the generic readahead logic.
1215 */
1216 if (VM_SequentialReadHint(area))
1217 page_cache_readahead(mapping, ra, file, pgoff, 1);
1218
1219 /*
1220 * Do we have something in the page cache already?
1221 */
1222retry_find:
1223 page = find_get_page(mapping, pgoff);
1224 if (!page) {
1225 unsigned long ra_pages;
1226
1227 if (VM_SequentialReadHint(area)) {
1228 handle_ra_miss(mapping, ra, pgoff);
1229 goto no_cached_page;
1230 }
1231 ra->mmap_miss++;
1232
1233 /*
1234 * Do we miss much more than hit in this file? If so,
1235 * stop bothering with read-ahead. It will only hurt.
1236 */
1237 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1238 goto no_cached_page;
1239
1240 /*
1241 * To keep the pgmajfault counter straight, we need to
1242 * check did_readaround, as this is an inner loop.
1243 */
1244 if (!did_readaround) {
1245 majmin = VM_FAULT_MAJOR;
1246 inc_page_state(pgmajfault);
1247 }
1248 did_readaround = 1;
1249 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1250 if (ra_pages) {
1251 pgoff_t start = 0;
1252
1253 if (pgoff > ra_pages / 2)
1254 start = pgoff - ra_pages / 2;
1255 do_page_cache_readahead(mapping, file, start, ra_pages);
1256 }
1257 page = find_get_page(mapping, pgoff);
1258 if (!page)
1259 goto no_cached_page;
1260 }
1261
1262 if (!did_readaround)
1263 ra->mmap_hit++;
1264
1265 /*
1266 * Ok, found a page in the page cache, now we need to check
1267 * that it's up-to-date.
1268 */
1269 if (!PageUptodate(page))
1270 goto page_not_uptodate;
1271
1272success:
1273 /*
1274 * Found the page and have a reference on it.
1275 */
1276 mark_page_accessed(page);
1277 if (type)
1278 *type = majmin;
1279 return page;
1280
1281outside_data_content:
1282 /*
1283 * An external ptracer can access pages that normally aren't
1284 * accessible..
1285 */
1286 if (area->vm_mm == current->mm)
1287 return NULL;
1288 /* Fall through to the non-read-ahead case */
1289no_cached_page:
1290 /*
1291 * We're only likely to ever get here if MADV_RANDOM is in
1292 * effect.
1293 */
1294 error = page_cache_read(file, pgoff);
1295 grab_swap_token();
1296
1297 /*
1298 * The page we want has now been added to the page cache.
1299 * In the unlikely event that someone removed it in the
1300 * meantime, we'll just come back here and read it again.
1301 */
1302 if (error >= 0)
1303 goto retry_find;
1304
1305 /*
1306 * An error return from page_cache_read can result if the
1307 * system is low on memory, or a problem occurs while trying
1308 * to schedule I/O.
1309 */
1310 if (error == -ENOMEM)
1311 return NOPAGE_OOM;
1312 return NULL;
1313
1314page_not_uptodate:
1315 if (!did_readaround) {
1316 majmin = VM_FAULT_MAJOR;
1317 inc_page_state(pgmajfault);
1318 }
1319 lock_page(page);
1320
1321 /* Did it get unhashed while we waited for it? */
1322 if (!page->mapping) {
1323 unlock_page(page);
1324 page_cache_release(page);
1325 goto retry_all;
1326 }
1327
1328 /* Did somebody else get it up-to-date? */
1329 if (PageUptodate(page)) {
1330 unlock_page(page);
1331 goto success;
1332 }
1333
1334 if (!mapping->a_ops->readpage(file, page)) {
1335 wait_on_page_locked(page);
1336 if (PageUptodate(page))
1337 goto success;
1338 }
1339
1340 /*
1341 * Umm, take care of errors if the page isn't up-to-date.
1342 * Try to re-read it _once_. We do this synchronously,
1343 * because there really aren't any performance issues here
1344 * and we need to check for errors.
1345 */
1346 lock_page(page);
1347
1348 /* Somebody truncated the page on us? */
1349 if (!page->mapping) {
1350 unlock_page(page);
1351 page_cache_release(page);
1352 goto retry_all;
1353 }
1354
1355 /* Somebody else successfully read it in? */
1356 if (PageUptodate(page)) {
1357 unlock_page(page);
1358 goto success;
1359 }
1360 ClearPageError(page);
1361 if (!mapping->a_ops->readpage(file, page)) {
1362 wait_on_page_locked(page);
1363 if (PageUptodate(page))
1364 goto success;
1365 }
1366
1367 /*
1368 * Things didn't work out. Return zero to tell the
1369 * mm layer so, possibly freeing the page cache page first.
1370 */
1371 page_cache_release(page);
1372 return NULL;
1373}
1374
1375EXPORT_SYMBOL(filemap_nopage);
1376
1377static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1378 int nonblock)
1379{
1380 struct address_space *mapping = file->f_mapping;
1381 struct page *page;
1382 int error;
1383
1384 /*
1385 * Do we have something in the page cache already?
1386 */
1387retry_find:
1388 page = find_get_page(mapping, pgoff);
1389 if (!page) {
1390 if (nonblock)
1391 return NULL;
1392 goto no_cached_page;
1393 }
1394
1395 /*
1396 * Ok, found a page in the page cache, now we need to check
1397 * that it's up-to-date.
1398 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001399 if (!PageUptodate(page)) {
1400 if (nonblock) {
1401 page_cache_release(page);
1402 return NULL;
1403 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001405 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406
1407success:
1408 /*
1409 * Found the page and have a reference on it.
1410 */
1411 mark_page_accessed(page);
1412 return page;
1413
1414no_cached_page:
1415 error = page_cache_read(file, pgoff);
1416
1417 /*
1418 * The page we want has now been added to the page cache.
1419 * In the unlikely event that someone removed it in the
1420 * meantime, we'll just come back here and read it again.
1421 */
1422 if (error >= 0)
1423 goto retry_find;
1424
1425 /*
1426 * An error return from page_cache_read can result if the
1427 * system is low on memory, or a problem occurs while trying
1428 * to schedule I/O.
1429 */
1430 return NULL;
1431
1432page_not_uptodate:
1433 lock_page(page);
1434
1435 /* Did it get unhashed while we waited for it? */
1436 if (!page->mapping) {
1437 unlock_page(page);
1438 goto err;
1439 }
1440
1441 /* Did somebody else get it up-to-date? */
1442 if (PageUptodate(page)) {
1443 unlock_page(page);
1444 goto success;
1445 }
1446
1447 if (!mapping->a_ops->readpage(file, page)) {
1448 wait_on_page_locked(page);
1449 if (PageUptodate(page))
1450 goto success;
1451 }
1452
1453 /*
1454 * Umm, take care of errors if the page isn't up-to-date.
1455 * Try to re-read it _once_. We do this synchronously,
1456 * because there really aren't any performance issues here
1457 * and we need to check for errors.
1458 */
1459 lock_page(page);
1460
1461 /* Somebody truncated the page on us? */
1462 if (!page->mapping) {
1463 unlock_page(page);
1464 goto err;
1465 }
1466 /* Somebody else successfully read it in? */
1467 if (PageUptodate(page)) {
1468 unlock_page(page);
1469 goto success;
1470 }
1471
1472 ClearPageError(page);
1473 if (!mapping->a_ops->readpage(file, page)) {
1474 wait_on_page_locked(page);
1475 if (PageUptodate(page))
1476 goto success;
1477 }
1478
1479 /*
1480 * Things didn't work out. Return zero to tell the
1481 * mm layer so, possibly freeing the page cache page first.
1482 */
1483err:
1484 page_cache_release(page);
1485
1486 return NULL;
1487}
1488
1489int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1490 unsigned long len, pgprot_t prot, unsigned long pgoff,
1491 int nonblock)
1492{
1493 struct file *file = vma->vm_file;
1494 struct address_space *mapping = file->f_mapping;
1495 struct inode *inode = mapping->host;
1496 unsigned long size;
1497 struct mm_struct *mm = vma->vm_mm;
1498 struct page *page;
1499 int err;
1500
1501 if (!nonblock)
1502 force_page_cache_readahead(mapping, vma->vm_file,
1503 pgoff, len >> PAGE_CACHE_SHIFT);
1504
1505repeat:
1506 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1507 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1508 return -EINVAL;
1509
1510 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001511
1512 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1513 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 if (!page && !nonblock)
1515 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001516
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 if (page) {
1518 err = install_page(mm, vma, addr, page, prot);
1519 if (err) {
1520 page_cache_release(page);
1521 return err;
1522 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001523 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001524 /* No page was found just because we can't read it in now (being
1525 * here implies nonblock != 0), but the page may exist, so set
1526 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 err = install_file_pte(mm, vma, addr, pgoff, prot);
1528 if (err)
1529 return err;
1530 }
1531
1532 len -= PAGE_SIZE;
1533 addr += PAGE_SIZE;
1534 pgoff++;
1535 if (len)
1536 goto repeat;
1537
1538 return 0;
1539}
1540
1541struct vm_operations_struct generic_file_vm_ops = {
1542 .nopage = filemap_nopage,
1543 .populate = filemap_populate,
1544};
1545
1546/* This is used for a general mmap of a disk file */
1547
1548int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1549{
1550 struct address_space *mapping = file->f_mapping;
1551
1552 if (!mapping->a_ops->readpage)
1553 return -ENOEXEC;
1554 file_accessed(file);
1555 vma->vm_ops = &generic_file_vm_ops;
1556 return 0;
1557}
1558EXPORT_SYMBOL(filemap_populate);
1559
1560/*
1561 * This is for filesystems which do not implement ->writepage.
1562 */
1563int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1564{
1565 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1566 return -EINVAL;
1567 return generic_file_mmap(file, vma);
1568}
1569#else
1570int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1571{
1572 return -ENOSYS;
1573}
1574int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1575{
1576 return -ENOSYS;
1577}
1578#endif /* CONFIG_MMU */
1579
1580EXPORT_SYMBOL(generic_file_mmap);
1581EXPORT_SYMBOL(generic_file_readonly_mmap);
1582
1583static inline struct page *__read_cache_page(struct address_space *mapping,
1584 unsigned long index,
1585 int (*filler)(void *,struct page*),
1586 void *data)
1587{
1588 struct page *page, *cached_page = NULL;
1589 int err;
1590repeat:
1591 page = find_get_page(mapping, index);
1592 if (!page) {
1593 if (!cached_page) {
1594 cached_page = page_cache_alloc_cold(mapping);
1595 if (!cached_page)
1596 return ERR_PTR(-ENOMEM);
1597 }
1598 err = add_to_page_cache_lru(cached_page, mapping,
1599 index, GFP_KERNEL);
1600 if (err == -EEXIST)
1601 goto repeat;
1602 if (err < 0) {
1603 /* Presumably ENOMEM for radix tree node */
1604 page_cache_release(cached_page);
1605 return ERR_PTR(err);
1606 }
1607 page = cached_page;
1608 cached_page = NULL;
1609 err = filler(data, page);
1610 if (err < 0) {
1611 page_cache_release(page);
1612 page = ERR_PTR(err);
1613 }
1614 }
1615 if (cached_page)
1616 page_cache_release(cached_page);
1617 return page;
1618}
1619
1620/*
1621 * Read into the page cache. If a page already exists,
1622 * and PageUptodate() is not set, try to fill the page.
1623 */
1624struct page *read_cache_page(struct address_space *mapping,
1625 unsigned long index,
1626 int (*filler)(void *,struct page*),
1627 void *data)
1628{
1629 struct page *page;
1630 int err;
1631
1632retry:
1633 page = __read_cache_page(mapping, index, filler, data);
1634 if (IS_ERR(page))
1635 goto out;
1636 mark_page_accessed(page);
1637 if (PageUptodate(page))
1638 goto out;
1639
1640 lock_page(page);
1641 if (!page->mapping) {
1642 unlock_page(page);
1643 page_cache_release(page);
1644 goto retry;
1645 }
1646 if (PageUptodate(page)) {
1647 unlock_page(page);
1648 goto out;
1649 }
1650 err = filler(data, page);
1651 if (err < 0) {
1652 page_cache_release(page);
1653 page = ERR_PTR(err);
1654 }
1655 out:
1656 return page;
1657}
1658
1659EXPORT_SYMBOL(read_cache_page);
1660
1661/*
1662 * If the page was newly created, increment its refcount and add it to the
1663 * caller's lru-buffering pagevec. This function is specifically for
1664 * generic_file_write().
1665 */
1666static inline struct page *
1667__grab_cache_page(struct address_space *mapping, unsigned long index,
1668 struct page **cached_page, struct pagevec *lru_pvec)
1669{
1670 int err;
1671 struct page *page;
1672repeat:
1673 page = find_lock_page(mapping, index);
1674 if (!page) {
1675 if (!*cached_page) {
1676 *cached_page = page_cache_alloc(mapping);
1677 if (!*cached_page)
1678 return NULL;
1679 }
1680 err = add_to_page_cache(*cached_page, mapping,
1681 index, GFP_KERNEL);
1682 if (err == -EEXIST)
1683 goto repeat;
1684 if (err == 0) {
1685 page = *cached_page;
1686 page_cache_get(page);
1687 if (!pagevec_add(lru_pvec, page))
1688 __pagevec_lru_add(lru_pvec);
1689 *cached_page = NULL;
1690 }
1691 }
1692 return page;
1693}
1694
1695/*
1696 * The logic we want is
1697 *
1698 * if suid or (sgid and xgrp)
1699 * remove privs
1700 */
1701int remove_suid(struct dentry *dentry)
1702{
1703 mode_t mode = dentry->d_inode->i_mode;
1704 int kill = 0;
1705 int result = 0;
1706
1707 /* suid always must be killed */
1708 if (unlikely(mode & S_ISUID))
1709 kill = ATTR_KILL_SUID;
1710
1711 /*
1712 * sgid without any exec bits is just a mandatory locking mark; leave
1713 * it alone. If some exec bits are set, it's a real sgid; kill it.
1714 */
1715 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1716 kill |= ATTR_KILL_SGID;
1717
1718 if (unlikely(kill && !capable(CAP_FSETID))) {
1719 struct iattr newattrs;
1720
1721 newattrs.ia_valid = ATTR_FORCE | kill;
1722 result = notify_change(dentry, &newattrs);
1723 }
1724 return result;
1725}
1726EXPORT_SYMBOL(remove_suid);
1727
Carsten Otteceffc072005-06-23 22:05:25 -07001728size_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729__filemap_copy_from_user_iovec(char *vaddr,
1730 const struct iovec *iov, size_t base, size_t bytes)
1731{
1732 size_t copied = 0, left = 0;
1733
1734 while (bytes) {
1735 char __user *buf = iov->iov_base + base;
1736 int copy = min(bytes, iov->iov_len - base);
1737
1738 base = 0;
1739 left = __copy_from_user_inatomic(vaddr, buf, copy);
1740 copied += copy;
1741 bytes -= copy;
1742 vaddr += copy;
1743 iov++;
1744
1745 if (unlikely(left)) {
1746 /* zero the rest of the target like __copy_from_user */
1747 if (bytes)
1748 memset(vaddr, 0, bytes);
1749 break;
1750 }
1751 }
1752 return copied - left;
1753}
1754
1755/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756 * Performs necessary checks before doing a write
1757 *
1758 * Can adjust writing position aor amount of bytes to write.
1759 * Returns appropriate error code that caller should return or
1760 * zero in case that write should be allowed.
1761 */
1762inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1763{
1764 struct inode *inode = file->f_mapping->host;
1765 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1766
1767 if (unlikely(*pos < 0))
1768 return -EINVAL;
1769
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 if (!isblk) {
1771 /* FIXME: this is for backwards compatibility with 2.4 */
1772 if (file->f_flags & O_APPEND)
1773 *pos = i_size_read(inode);
1774
1775 if (limit != RLIM_INFINITY) {
1776 if (*pos >= limit) {
1777 send_sig(SIGXFSZ, current, 0);
1778 return -EFBIG;
1779 }
1780 if (*count > limit - (typeof(limit))*pos) {
1781 *count = limit - (typeof(limit))*pos;
1782 }
1783 }
1784 }
1785
1786 /*
1787 * LFS rule
1788 */
1789 if (unlikely(*pos + *count > MAX_NON_LFS &&
1790 !(file->f_flags & O_LARGEFILE))) {
1791 if (*pos >= MAX_NON_LFS) {
1792 send_sig(SIGXFSZ, current, 0);
1793 return -EFBIG;
1794 }
1795 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1796 *count = MAX_NON_LFS - (unsigned long)*pos;
1797 }
1798 }
1799
1800 /*
1801 * Are we about to exceed the fs block limit ?
1802 *
1803 * If we have written data it becomes a short write. If we have
1804 * exceeded without writing data we send a signal and return EFBIG.
1805 * Linus frestrict idea will clean these up nicely..
1806 */
1807 if (likely(!isblk)) {
1808 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1809 if (*count || *pos > inode->i_sb->s_maxbytes) {
1810 send_sig(SIGXFSZ, current, 0);
1811 return -EFBIG;
1812 }
1813 /* zero-length writes at ->s_maxbytes are OK */
1814 }
1815
1816 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1817 *count = inode->i_sb->s_maxbytes - *pos;
1818 } else {
1819 loff_t isize;
1820 if (bdev_read_only(I_BDEV(inode)))
1821 return -EPERM;
1822 isize = i_size_read(inode);
1823 if (*pos >= isize) {
1824 if (*count || *pos > isize)
1825 return -ENOSPC;
1826 }
1827
1828 if (*pos + *count > isize)
1829 *count = isize - *pos;
1830 }
1831 return 0;
1832}
1833EXPORT_SYMBOL(generic_write_checks);
1834
1835ssize_t
1836generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1837 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1838 size_t count, size_t ocount)
1839{
1840 struct file *file = iocb->ki_filp;
1841 struct address_space *mapping = file->f_mapping;
1842 struct inode *inode = mapping->host;
1843 ssize_t written;
1844
1845 if (count != ocount)
1846 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1847
1848 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1849 if (written > 0) {
1850 loff_t end = pos + written;
1851 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1852 i_size_write(inode, end);
1853 mark_inode_dirty(inode);
1854 }
1855 *ppos = end;
1856 }
1857
1858 /*
1859 * Sync the fs metadata but not the minor inode changes and
1860 * of course not the data as we did direct DMA for the IO.
1861 * i_sem is held, which protects generic_osync_inode() from
1862 * livelocking.
1863 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07001864 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1865 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1866 if (err < 0)
1867 written = err;
1868 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869 if (written == count && !is_sync_kiocb(iocb))
1870 written = -EIOCBQUEUED;
1871 return written;
1872}
1873EXPORT_SYMBOL(generic_file_direct_write);
1874
1875ssize_t
1876generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1877 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1878 size_t count, ssize_t written)
1879{
1880 struct file *file = iocb->ki_filp;
1881 struct address_space * mapping = file->f_mapping;
1882 struct address_space_operations *a_ops = mapping->a_ops;
1883 struct inode *inode = mapping->host;
1884 long status = 0;
1885 struct page *page;
1886 struct page *cached_page = NULL;
1887 size_t bytes;
1888 struct pagevec lru_pvec;
1889 const struct iovec *cur_iov = iov; /* current iovec */
1890 size_t iov_base = 0; /* offset in the current iovec */
1891 char __user *buf;
1892
1893 pagevec_init(&lru_pvec, 0);
1894
1895 /*
1896 * handle partial DIO write. Adjust cur_iov if needed.
1897 */
1898 if (likely(nr_segs == 1))
1899 buf = iov->iov_base + written;
1900 else {
1901 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001902 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903 }
1904
1905 do {
1906 unsigned long index;
1907 unsigned long offset;
Martin Schwidefskya5117182005-06-06 13:35:54 -07001908 unsigned long maxlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 size_t copied;
1910
1911 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1912 index = pos >> PAGE_CACHE_SHIFT;
1913 bytes = PAGE_CACHE_SIZE - offset;
1914 if (bytes > count)
1915 bytes = count;
1916
1917 /*
1918 * Bring in the user page that we will copy from _first_.
1919 * Otherwise there's a nasty deadlock on copying from the
1920 * same page as we're writing to, without it being marked
1921 * up-to-date.
1922 */
Martin Schwidefskya5117182005-06-06 13:35:54 -07001923 maxlen = cur_iov->iov_len - iov_base;
1924 if (maxlen > bytes)
1925 maxlen = bytes;
1926 fault_in_pages_readable(buf, maxlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001927
1928 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1929 if (!page) {
1930 status = -ENOMEM;
1931 break;
1932 }
1933
1934 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1935 if (unlikely(status)) {
1936 loff_t isize = i_size_read(inode);
1937 /*
1938 * prepare_write() may have instantiated a few blocks
1939 * outside i_size. Trim these off again.
1940 */
1941 unlock_page(page);
1942 page_cache_release(page);
1943 if (pos + bytes > isize)
1944 vmtruncate(inode, isize);
1945 break;
1946 }
1947 if (likely(nr_segs == 1))
1948 copied = filemap_copy_from_user(page, offset,
1949 buf, bytes);
1950 else
1951 copied = filemap_copy_from_user_iovec(page, offset,
1952 cur_iov, iov_base, bytes);
1953 flush_dcache_page(page);
1954 status = a_ops->commit_write(file, page, offset, offset+bytes);
1955 if (likely(copied > 0)) {
1956 if (!status)
1957 status = copied;
1958
1959 if (status >= 0) {
1960 written += status;
1961 count -= status;
1962 pos += status;
1963 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001964 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965 filemap_set_next_iovec(&cur_iov,
1966 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07001967 if (count)
1968 buf = cur_iov->iov_base +
1969 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07001970 } else {
1971 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001972 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973 }
1974 }
1975 if (unlikely(copied != bytes))
1976 if (status >= 0)
1977 status = -EFAULT;
1978 unlock_page(page);
1979 mark_page_accessed(page);
1980 page_cache_release(page);
1981 if (status < 0)
1982 break;
1983 balance_dirty_pages_ratelimited(mapping);
1984 cond_resched();
1985 } while (count);
1986 *ppos = pos;
1987
1988 if (cached_page)
1989 page_cache_release(cached_page);
1990
1991 /*
1992 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
1993 */
1994 if (likely(status >= 0)) {
1995 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1996 if (!a_ops->writepage || !is_sync_kiocb(iocb))
1997 status = generic_osync_inode(inode, mapping,
1998 OSYNC_METADATA|OSYNC_DATA);
1999 }
2000 }
2001
2002 /*
2003 * If we get here for O_DIRECT writes then we must have fallen through
2004 * to buffered writes (block instantiation inside i_size). So we sync
2005 * the file data here, to try to honour O_DIRECT expectations.
2006 */
2007 if (unlikely(file->f_flags & O_DIRECT) && written)
2008 status = filemap_write_and_wait(mapping);
2009
2010 pagevec_lru_add(&lru_pvec);
2011 return written ? written : status;
2012}
2013EXPORT_SYMBOL(generic_file_buffered_write);
2014
Adrian Bunk5ce78522005-09-10 00:26:28 -07002015static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2017 unsigned long nr_segs, loff_t *ppos)
2018{
2019 struct file *file = iocb->ki_filp;
2020 struct address_space * mapping = file->f_mapping;
2021 size_t ocount; /* original count */
2022 size_t count; /* after file limit checks */
2023 struct inode *inode = mapping->host;
2024 unsigned long seg;
2025 loff_t pos;
2026 ssize_t written;
2027 ssize_t err;
2028
2029 ocount = 0;
2030 for (seg = 0; seg < nr_segs; seg++) {
2031 const struct iovec *iv = &iov[seg];
2032
2033 /*
2034 * If any segment has a negative length, or the cumulative
2035 * length ever wraps negative then return -EINVAL.
2036 */
2037 ocount += iv->iov_len;
2038 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2039 return -EINVAL;
2040 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2041 continue;
2042 if (seg == 0)
2043 return -EFAULT;
2044 nr_segs = seg;
2045 ocount -= iv->iov_len; /* This segment is no good */
2046 break;
2047 }
2048
2049 count = ocount;
2050 pos = *ppos;
2051
2052 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2053
2054 /* We can write back this queue in page reclaim */
2055 current->backing_dev_info = mapping->backing_dev_info;
2056 written = 0;
2057
2058 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2059 if (err)
2060 goto out;
2061
2062 if (count == 0)
2063 goto out;
2064
2065 err = remove_suid(file->f_dentry);
2066 if (err)
2067 goto out;
2068
2069 inode_update_time(inode, 1);
2070
2071 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2072 if (unlikely(file->f_flags & O_DIRECT)) {
2073 written = generic_file_direct_write(iocb, iov,
2074 &nr_segs, pos, ppos, count, ocount);
2075 if (written < 0 || written == count)
2076 goto out;
2077 /*
2078 * direct-io write to a hole: fall through to buffered I/O
2079 * for completing the rest of the request.
2080 */
2081 pos += written;
2082 count -= written;
2083 }
2084
2085 written = generic_file_buffered_write(iocb, iov, nr_segs,
2086 pos, ppos, count, written);
2087out:
2088 current->backing_dev_info = NULL;
2089 return written ? written : err;
2090}
2091EXPORT_SYMBOL(generic_file_aio_write_nolock);
2092
2093ssize_t
2094generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2095 unsigned long nr_segs, loff_t *ppos)
2096{
2097 struct file *file = iocb->ki_filp;
2098 struct address_space *mapping = file->f_mapping;
2099 struct inode *inode = mapping->host;
2100 ssize_t ret;
2101 loff_t pos = *ppos;
2102
2103 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2104
2105 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2106 int err;
2107
2108 err = sync_page_range_nolock(inode, mapping, pos, ret);
2109 if (err < 0)
2110 ret = err;
2111 }
2112 return ret;
2113}
2114
Adrian Bunk5ce78522005-09-10 00:26:28 -07002115static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002116__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2117 unsigned long nr_segs, loff_t *ppos)
2118{
2119 struct kiocb kiocb;
2120 ssize_t ret;
2121
2122 init_sync_kiocb(&kiocb, file);
2123 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2124 if (ret == -EIOCBQUEUED)
2125 ret = wait_on_sync_kiocb(&kiocb);
2126 return ret;
2127}
2128
2129ssize_t
2130generic_file_write_nolock(struct file *file, const struct iovec *iov,
2131 unsigned long nr_segs, loff_t *ppos)
2132{
2133 struct kiocb kiocb;
2134 ssize_t ret;
2135
2136 init_sync_kiocb(&kiocb, file);
2137 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2138 if (-EIOCBQUEUED == ret)
2139 ret = wait_on_sync_kiocb(&kiocb);
2140 return ret;
2141}
2142EXPORT_SYMBOL(generic_file_write_nolock);
2143
2144ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2145 size_t count, loff_t pos)
2146{
2147 struct file *file = iocb->ki_filp;
2148 struct address_space *mapping = file->f_mapping;
2149 struct inode *inode = mapping->host;
2150 ssize_t ret;
2151 struct iovec local_iov = { .iov_base = (void __user *)buf,
2152 .iov_len = count };
2153
2154 BUG_ON(iocb->ki_pos != pos);
2155
2156 down(&inode->i_sem);
2157 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2158 &iocb->ki_pos);
2159 up(&inode->i_sem);
2160
2161 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2162 ssize_t err;
2163
2164 err = sync_page_range(inode, mapping, pos, ret);
2165 if (err < 0)
2166 ret = err;
2167 }
2168 return ret;
2169}
2170EXPORT_SYMBOL(generic_file_aio_write);
2171
2172ssize_t generic_file_write(struct file *file, const char __user *buf,
2173 size_t count, loff_t *ppos)
2174{
2175 struct address_space *mapping = file->f_mapping;
2176 struct inode *inode = mapping->host;
2177 ssize_t ret;
2178 struct iovec local_iov = { .iov_base = (void __user *)buf,
2179 .iov_len = count };
2180
2181 down(&inode->i_sem);
2182 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
2183 up(&inode->i_sem);
2184
2185 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2186 ssize_t err;
2187
2188 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2189 if (err < 0)
2190 ret = err;
2191 }
2192 return ret;
2193}
2194EXPORT_SYMBOL(generic_file_write);
2195
2196ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2197 unsigned long nr_segs, loff_t *ppos)
2198{
2199 struct kiocb kiocb;
2200 ssize_t ret;
2201
2202 init_sync_kiocb(&kiocb, filp);
2203 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2204 if (-EIOCBQUEUED == ret)
2205 ret = wait_on_sync_kiocb(&kiocb);
2206 return ret;
2207}
2208EXPORT_SYMBOL(generic_file_readv);
2209
2210ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2211 unsigned long nr_segs, loff_t *ppos)
2212{
2213 struct address_space *mapping = file->f_mapping;
2214 struct inode *inode = mapping->host;
2215 ssize_t ret;
2216
2217 down(&inode->i_sem);
2218 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
2219 up(&inode->i_sem);
2220
2221 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2222 int err;
2223
2224 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2225 if (err < 0)
2226 ret = err;
2227 }
2228 return ret;
2229}
2230EXPORT_SYMBOL(generic_file_writev);
2231
2232/*
2233 * Called under i_sem for writes to S_ISREG files. Returns -EIO if something
2234 * went wrong during pagecache shootdown.
2235 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002236static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2238 loff_t offset, unsigned long nr_segs)
2239{
2240 struct file *file = iocb->ki_filp;
2241 struct address_space *mapping = file->f_mapping;
2242 ssize_t retval;
2243 size_t write_len = 0;
2244
2245 /*
2246 * If it's a write, unmap all mmappings of the file up-front. This
2247 * will cause any pte dirty bits to be propagated into the pageframes
2248 * for the subsequent filemap_write_and_wait().
2249 */
2250 if (rw == WRITE) {
2251 write_len = iov_length(iov, nr_segs);
2252 if (mapping_mapped(mapping))
2253 unmap_mapping_range(mapping, offset, write_len, 0);
2254 }
2255
2256 retval = filemap_write_and_wait(mapping);
2257 if (retval == 0) {
2258 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2259 offset, nr_segs);
2260 if (rw == WRITE && mapping->nrpages) {
2261 pgoff_t end = (offset + write_len - 1)
2262 >> PAGE_CACHE_SHIFT;
2263 int err = invalidate_inode_pages2_range(mapping,
2264 offset >> PAGE_CACHE_SHIFT, end);
2265 if (err)
2266 retval = err;
2267 }
2268 }
2269 return retval;
2270}