blob: 44da3d47699485004994c6af302c7406d606c569 [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>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080018#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/kernel_stat.h>
20#include <linux/mm.h>
21#include <linux/swap.h>
22#include <linux/mman.h>
23#include <linux/pagemap.h>
24#include <linux/file.h>
25#include <linux/uio.h>
26#include <linux/hash.h>
27#include <linux/writeback.h>
28#include <linux/pagevec.h>
29#include <linux/blkdev.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
Carsten Otteceffc072005-06-23 22:05:25 -070032#include "filemap.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070033/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 * FIXME: remove all knowledge of the buffer layer from the core VM
35 */
36#include <linux/buffer_head.h> /* for generic_osync_inode */
37
38#include <asm/uaccess.h>
39#include <asm/mman.h>
40
Adrian Bunk5ce78522005-09-10 00:26:28 -070041static ssize_t
42generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
43 loff_t offset, unsigned long nr_segs);
44
Linus Torvalds1da177e2005-04-16 15:20:36 -070045/*
46 * Shared mappings implemented 30.11.1994. It's not fully working yet,
47 * though.
48 *
49 * Shared mappings now work. 15.8.1995 Bruno.
50 *
51 * finished 'unifying' the page and buffer cache and SMP-threaded the
52 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
53 *
54 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
55 */
56
57/*
58 * Lock ordering:
59 *
60 * ->i_mmap_lock (vmtruncate)
61 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070062 * ->swap_lock (exclusive_swap_page, others)
63 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080065 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 * ->i_mmap_lock (truncate->unmap_mapping_range)
67 *
68 * ->mmap_sem
69 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070070 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
72 *
73 * ->mmap_sem
74 * ->lock_page (access_process_vm)
75 *
76 * ->mmap_sem
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080077 * ->i_mutex (msync)
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080079 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 * ->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
Hugh Dickinsb8072f02005-10-29 18:16:41 -070090 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070092 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070093 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 * ->private_lock (try_to_unmap_one)
95 * ->tree_lock (try_to_unmap_one)
96 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -080097 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 * ->private_lock (page_remove_rmap->set_page_dirty)
99 * ->tree_lock (page_remove_rmap->set_page_dirty)
100 * ->inode_lock (page_remove_rmap->set_page_dirty)
101 * ->inode_lock (zap_pte_range->set_page_dirty)
102 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
103 *
104 * ->task->proc_lock
105 * ->dcache_lock (proc_pid_lookup)
106 */
107
108/*
109 * Remove a page from the page cache and free it. Caller has to make
110 * sure the page is locked and that nobody else uses it - or that usage
111 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
112 */
113void __remove_from_page_cache(struct page *page)
114{
115 struct address_space *mapping = page->mapping;
116
117 radix_tree_delete(&mapping->page_tree, page->index);
118 page->mapping = NULL;
119 mapping->nrpages--;
120 pagecache_acct(-1);
121}
122
123void remove_from_page_cache(struct page *page)
124{
125 struct address_space *mapping = page->mapping;
126
Matt Mackallcd7619d2005-05-01 08:59:01 -0700127 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
129 write_lock_irq(&mapping->tree_lock);
130 __remove_from_page_cache(page);
131 write_unlock_irq(&mapping->tree_lock);
132}
133
134static int sync_page(void *word)
135{
136 struct address_space *mapping;
137 struct page *page;
138
Andi Kleen07808b72005-11-05 17:25:53 +0100139 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
141 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700142 * page_mapping() is being called without PG_locked held.
143 * Some knowledge of the state and use of the page is used to
144 * reduce the requirements down to a memory barrier.
145 * The danger here is of a stale page_mapping() return value
146 * indicating a struct address_space different from the one it's
147 * associated with when it is associated with one.
148 * After smp_mb(), it's either the correct page_mapping() for
149 * the page, or an old page_mapping() and the page's own
150 * page_mapping() has gone NULL.
151 * The ->sync_page() address_space operation must tolerate
152 * page_mapping() going NULL. By an amazing coincidence,
153 * this comes about because none of the users of the page
154 * in the ->sync_page() methods make essential use of the
155 * page_mapping(), merely passing the page down to the backing
156 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700157 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700158 * of interest. When page_mapping() does go NULL, the entire
159 * call stack gracefully ignores the page and returns.
160 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 */
162 smp_mb();
163 mapping = page_mapping(page);
164 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
165 mapping->a_ops->sync_page(page);
166 io_schedule();
167 return 0;
168}
169
170/**
171 * filemap_fdatawrite_range - start writeback against all of a mapping's
172 * dirty pages that lie within the byte offsets <start, end>
Martin Waitz67be2dd2005-05-01 08:59:26 -0700173 * @mapping: address space structure to write
174 * @start: offset in bytes where the range starts
175 * @end: offset in bytes where the range ends
176 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 *
178 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
179 * opposed to a regular memory * cleansing writeback. The difference between
180 * these two operations is that if a dirty page/buffer is encountered, it must
181 * be waited upon, and not just skipped over.
182 */
183static int __filemap_fdatawrite_range(struct address_space *mapping,
184 loff_t start, loff_t end, int sync_mode)
185{
186 int ret;
187 struct writeback_control wbc = {
188 .sync_mode = sync_mode,
189 .nr_to_write = mapping->nrpages * 2,
190 .start = start,
191 .end = end,
192 };
193
194 if (!mapping_cap_writeback_dirty(mapping))
195 return 0;
196
197 ret = do_writepages(mapping, &wbc);
198 return ret;
199}
200
201static inline int __filemap_fdatawrite(struct address_space *mapping,
202 int sync_mode)
203{
204 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
205}
206
207int filemap_fdatawrite(struct address_space *mapping)
208{
209 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
210}
211EXPORT_SYMBOL(filemap_fdatawrite);
212
213static int filemap_fdatawrite_range(struct address_space *mapping,
214 loff_t start, loff_t end)
215{
216 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
217}
218
219/*
220 * This is a mostly non-blocking flush. Not suitable for data-integrity
221 * purposes - I/O may not be started against all dirty pages.
222 */
223int filemap_flush(struct address_space *mapping)
224{
225 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
226}
227EXPORT_SYMBOL(filemap_flush);
228
229/*
230 * Wait for writeback to complete against pages indexed by start->end
231 * inclusive
232 */
233static int wait_on_page_writeback_range(struct address_space *mapping,
234 pgoff_t start, pgoff_t end)
235{
236 struct pagevec pvec;
237 int nr_pages;
238 int ret = 0;
239 pgoff_t index;
240
241 if (end < start)
242 return 0;
243
244 pagevec_init(&pvec, 0);
245 index = start;
246 while ((index <= end) &&
247 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
248 PAGECACHE_TAG_WRITEBACK,
249 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
250 unsigned i;
251
252 for (i = 0; i < nr_pages; i++) {
253 struct page *page = pvec.pages[i];
254
255 /* until radix tree lookup accepts end_index */
256 if (page->index > end)
257 continue;
258
259 wait_on_page_writeback(page);
260 if (PageError(page))
261 ret = -EIO;
262 }
263 pagevec_release(&pvec);
264 cond_resched();
265 }
266
267 /* Check for outstanding write errors */
268 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
269 ret = -ENOSPC;
270 if (test_and_clear_bit(AS_EIO, &mapping->flags))
271 ret = -EIO;
272
273 return ret;
274}
275
276/*
277 * Write and wait upon all the pages in the passed range. This is a "data
278 * integrity" operation. It waits upon in-flight writeout before starting and
279 * waiting upon new writeout. If there was an IO error, return it.
280 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800281 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 * it is otherwise livelockable.
283 */
284int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800285 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286{
287 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
288 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
289 int ret;
290
291 if (!mapping_cap_writeback_dirty(mapping) || !count)
292 return 0;
293 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
294 if (ret == 0) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800295 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800297 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 }
299 if (ret == 0)
300 ret = wait_on_page_writeback_range(mapping, start, end);
301 return ret;
302}
303EXPORT_SYMBOL(sync_page_range);
304
305/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800306 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 * as it forces O_SYNC writers to different parts of the same file
308 * to be serialised right until io completion.
309 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800310int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
311 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312{
313 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
314 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
315 int ret;
316
317 if (!mapping_cap_writeback_dirty(mapping) || !count)
318 return 0;
319 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
320 if (ret == 0)
321 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
322 if (ret == 0)
323 ret = wait_on_page_writeback_range(mapping, start, end);
324 return ret;
325}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800326EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327
328/**
329 * filemap_fdatawait - walk the list of under-writeback pages of the given
330 * address space and wait for all of them.
331 *
332 * @mapping: address space structure to wait for
333 */
334int filemap_fdatawait(struct address_space *mapping)
335{
336 loff_t i_size = i_size_read(mapping->host);
337
338 if (i_size == 0)
339 return 0;
340
341 return wait_on_page_writeback_range(mapping, 0,
342 (i_size - 1) >> PAGE_CACHE_SHIFT);
343}
344EXPORT_SYMBOL(filemap_fdatawait);
345
346int filemap_write_and_wait(struct address_space *mapping)
347{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800348 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
350 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800351 err = filemap_fdatawrite(mapping);
352 /*
353 * Even if the above returned error, the pages may be
354 * written partially (e.g. -ENOSPC), so we wait for it.
355 * But the -EIO is special case, it may indicate the worst
356 * thing (e.g. bug) happened, so we avoid waiting for it.
357 */
358 if (err != -EIO) {
359 int err2 = filemap_fdatawait(mapping);
360 if (!err)
361 err = err2;
362 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800364 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800366EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367
368int filemap_write_and_wait_range(struct address_space *mapping,
369 loff_t lstart, loff_t lend)
370{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800371 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372
373 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800374 err = __filemap_fdatawrite_range(mapping, lstart, lend,
375 WB_SYNC_ALL);
376 /* See comment of filemap_write_and_wait() */
377 if (err != -EIO) {
378 int err2 = wait_on_page_writeback_range(mapping,
379 lstart >> PAGE_CACHE_SHIFT,
380 lend >> PAGE_CACHE_SHIFT);
381 if (!err)
382 err = err2;
383 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800385 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386}
387
388/*
389 * This function is used to add newly allocated pagecache pages:
390 * the page is new, so we can just run SetPageLocked() against it.
391 * The other page state flags were set by rmqueue().
392 *
393 * This function does not add the page to the LRU. The caller must do that.
394 */
395int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400396 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397{
398 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
399
400 if (error == 0) {
401 write_lock_irq(&mapping->tree_lock);
402 error = radix_tree_insert(&mapping->page_tree, offset, page);
403 if (!error) {
404 page_cache_get(page);
405 SetPageLocked(page);
406 page->mapping = mapping;
407 page->index = offset;
408 mapping->nrpages++;
409 pagecache_acct(1);
410 }
411 write_unlock_irq(&mapping->tree_lock);
412 radix_tree_preload_end();
413 }
414 return error;
415}
416
417EXPORT_SYMBOL(add_to_page_cache);
418
419int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400420 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421{
422 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
423 if (ret == 0)
424 lru_cache_add(page);
425 return ret;
426}
427
428/*
429 * In order to wait for pages to become available there must be
430 * waitqueues associated with pages. By using a hash table of
431 * waitqueues where the bucket discipline is to maintain all
432 * waiters on the same queue and wake all when any of the pages
433 * become available, and for the woken contexts to check to be
434 * sure the appropriate page became available, this saves space
435 * at a cost of "thundering herd" phenomena during rare hash
436 * collisions.
437 */
438static wait_queue_head_t *page_waitqueue(struct page *page)
439{
440 const struct zone *zone = page_zone(page);
441
442 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
443}
444
445static inline void wake_up_page(struct page *page, int bit)
446{
447 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
448}
449
450void fastcall wait_on_page_bit(struct page *page, int bit_nr)
451{
452 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
453
454 if (test_bit(bit_nr, &page->flags))
455 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
456 TASK_UNINTERRUPTIBLE);
457}
458EXPORT_SYMBOL(wait_on_page_bit);
459
460/**
461 * unlock_page() - unlock a locked page
462 *
463 * @page: the page
464 *
465 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
466 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
467 * mechananism between PageLocked pages and PageWriteback pages is shared.
468 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
469 *
470 * The first mb is necessary to safely close the critical section opened by the
471 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
472 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
473 * parallel wait_on_page_locked()).
474 */
475void fastcall unlock_page(struct page *page)
476{
477 smp_mb__before_clear_bit();
478 if (!TestClearPageLocked(page))
479 BUG();
480 smp_mb__after_clear_bit();
481 wake_up_page(page, PG_locked);
482}
483EXPORT_SYMBOL(unlock_page);
484
485/*
486 * End writeback against a page.
487 */
488void end_page_writeback(struct page *page)
489{
490 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
491 if (!test_clear_page_writeback(page))
492 BUG();
493 }
494 smp_mb__after_clear_bit();
495 wake_up_page(page, PG_writeback);
496}
497EXPORT_SYMBOL(end_page_writeback);
498
499/*
500 * Get a lock on the page, assuming we need to sleep to get it.
501 *
502 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
503 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
504 * chances are that on the second loop, the block layer's plug list is empty,
505 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
506 */
507void fastcall __lock_page(struct page *page)
508{
509 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
510
511 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
512 TASK_UNINTERRUPTIBLE);
513}
514EXPORT_SYMBOL(__lock_page);
515
516/*
517 * a rather lightweight function, finding and getting a reference to a
518 * hashed page atomically.
519 */
520struct page * find_get_page(struct address_space *mapping, unsigned long offset)
521{
522 struct page *page;
523
524 read_lock_irq(&mapping->tree_lock);
525 page = radix_tree_lookup(&mapping->page_tree, offset);
526 if (page)
527 page_cache_get(page);
528 read_unlock_irq(&mapping->tree_lock);
529 return page;
530}
531
532EXPORT_SYMBOL(find_get_page);
533
534/*
535 * Same as above, but trylock it instead of incrementing the count.
536 */
537struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
538{
539 struct page *page;
540
541 read_lock_irq(&mapping->tree_lock);
542 page = radix_tree_lookup(&mapping->page_tree, offset);
543 if (page && TestSetPageLocked(page))
544 page = NULL;
545 read_unlock_irq(&mapping->tree_lock);
546 return page;
547}
548
549EXPORT_SYMBOL(find_trylock_page);
550
551/**
552 * find_lock_page - locate, pin and lock a pagecache page
553 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700554 * @mapping: the address_space to search
555 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 *
557 * Locates the desired pagecache page, locks it, increments its reference
558 * count and returns its address.
559 *
560 * Returns zero if the page was not present. find_lock_page() may sleep.
561 */
562struct page *find_lock_page(struct address_space *mapping,
563 unsigned long offset)
564{
565 struct page *page;
566
567 read_lock_irq(&mapping->tree_lock);
568repeat:
569 page = radix_tree_lookup(&mapping->page_tree, offset);
570 if (page) {
571 page_cache_get(page);
572 if (TestSetPageLocked(page)) {
573 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800574 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 read_lock_irq(&mapping->tree_lock);
576
577 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800578 if (unlikely(page->mapping != mapping ||
579 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 unlock_page(page);
581 page_cache_release(page);
582 goto repeat;
583 }
584 }
585 }
586 read_unlock_irq(&mapping->tree_lock);
587 return page;
588}
589
590EXPORT_SYMBOL(find_lock_page);
591
592/**
593 * find_or_create_page - locate or add a pagecache page
594 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700595 * @mapping: the page's address_space
596 * @index: the page's index into the mapping
597 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 *
599 * Locates a page in the pagecache. If the page is not present, a new page
600 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
601 * LRU list. The returned page is locked and has its reference count
602 * incremented.
603 *
604 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
605 * allocation!
606 *
607 * find_or_create_page() returns the desired page's address, or zero on
608 * memory exhaustion.
609 */
610struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400611 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612{
613 struct page *page, *cached_page = NULL;
614 int err;
615repeat:
616 page = find_lock_page(mapping, index);
617 if (!page) {
618 if (!cached_page) {
619 cached_page = alloc_page(gfp_mask);
620 if (!cached_page)
621 return NULL;
622 }
623 err = add_to_page_cache_lru(cached_page, mapping,
624 index, gfp_mask);
625 if (!err) {
626 page = cached_page;
627 cached_page = NULL;
628 } else if (err == -EEXIST)
629 goto repeat;
630 }
631 if (cached_page)
632 page_cache_release(cached_page);
633 return page;
634}
635
636EXPORT_SYMBOL(find_or_create_page);
637
638/**
639 * find_get_pages - gang pagecache lookup
640 * @mapping: The address_space to search
641 * @start: The starting page index
642 * @nr_pages: The maximum number of pages
643 * @pages: Where the resulting pages are placed
644 *
645 * find_get_pages() will search for and return a group of up to
646 * @nr_pages pages in the mapping. The pages are placed at @pages.
647 * find_get_pages() takes a reference against the returned pages.
648 *
649 * The search returns a group of mapping-contiguous pages with ascending
650 * indexes. There may be holes in the indices due to not-present pages.
651 *
652 * find_get_pages() returns the number of pages which were found.
653 */
654unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
655 unsigned int nr_pages, struct page **pages)
656{
657 unsigned int i;
658 unsigned int ret;
659
660 read_lock_irq(&mapping->tree_lock);
661 ret = radix_tree_gang_lookup(&mapping->page_tree,
662 (void **)pages, start, nr_pages);
663 for (i = 0; i < ret; i++)
664 page_cache_get(pages[i]);
665 read_unlock_irq(&mapping->tree_lock);
666 return ret;
667}
668
669/*
670 * Like find_get_pages, except we only return pages which are tagged with
671 * `tag'. We update *index to index the next page for the traversal.
672 */
673unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
674 int tag, unsigned int nr_pages, struct page **pages)
675{
676 unsigned int i;
677 unsigned int ret;
678
679 read_lock_irq(&mapping->tree_lock);
680 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
681 (void **)pages, *index, nr_pages, tag);
682 for (i = 0; i < ret; i++)
683 page_cache_get(pages[i]);
684 if (ret)
685 *index = pages[ret - 1]->index + 1;
686 read_unlock_irq(&mapping->tree_lock);
687 return ret;
688}
689
690/*
691 * Same as grab_cache_page, but do not wait if the page is unavailable.
692 * This is intended for speculative data generators, where the data can
693 * be regenerated if the page couldn't be grabbed. This routine should
694 * be safe to call while holding the lock for another page.
695 *
696 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
697 * and deadlock against the caller's locked page.
698 */
699struct page *
700grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
701{
702 struct page *page = find_get_page(mapping, index);
Al Viro6daa0e22005-10-21 03:18:50 -0400703 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704
705 if (page) {
706 if (!TestSetPageLocked(page))
707 return page;
708 page_cache_release(page);
709 return NULL;
710 }
711 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
712 page = alloc_pages(gfp_mask, 0);
713 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
714 page_cache_release(page);
715 page = NULL;
716 }
717 return page;
718}
719
720EXPORT_SYMBOL(grab_cache_page_nowait);
721
722/*
723 * This is a generic file read routine, and uses the
724 * mapping->a_ops->readpage() function for the actual low-level
725 * stuff.
726 *
727 * This is really ugly. But the goto's actually try to clarify some
728 * of the logic when it comes to error handling etc.
729 *
730 * Note the struct file* is only passed for the use of readpage. It may be
731 * NULL.
732 */
733void do_generic_mapping_read(struct address_space *mapping,
734 struct file_ra_state *_ra,
735 struct file *filp,
736 loff_t *ppos,
737 read_descriptor_t *desc,
738 read_actor_t actor)
739{
740 struct inode *inode = mapping->host;
741 unsigned long index;
742 unsigned long end_index;
743 unsigned long offset;
744 unsigned long last_index;
745 unsigned long next_index;
746 unsigned long prev_index;
747 loff_t isize;
748 struct page *cached_page;
749 int error;
750 struct file_ra_state ra = *_ra;
751
752 cached_page = NULL;
753 index = *ppos >> PAGE_CACHE_SHIFT;
754 next_index = index;
755 prev_index = ra.prev_page;
756 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
757 offset = *ppos & ~PAGE_CACHE_MASK;
758
759 isize = i_size_read(inode);
760 if (!isize)
761 goto out;
762
763 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
764 for (;;) {
765 struct page *page;
766 unsigned long nr, ret;
767
768 /* nr is the maximum number of bytes to copy from this page */
769 nr = PAGE_CACHE_SIZE;
770 if (index >= end_index) {
771 if (index > end_index)
772 goto out;
773 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
774 if (nr <= offset) {
775 goto out;
776 }
777 }
778 nr = nr - offset;
779
780 cond_resched();
781 if (index == next_index)
782 next_index = page_cache_readahead(mapping, &ra, filp,
783 index, last_index - index);
784
785find_page:
786 page = find_get_page(mapping, index);
787 if (unlikely(page == NULL)) {
788 handle_ra_miss(mapping, &ra, index);
789 goto no_cached_page;
790 }
791 if (!PageUptodate(page))
792 goto page_not_up_to_date;
793page_ok:
794
795 /* If users can be writing to this page using arbitrary
796 * virtual addresses, take care about potential aliasing
797 * before reading the page on the kernel side.
798 */
799 if (mapping_writably_mapped(mapping))
800 flush_dcache_page(page);
801
802 /*
803 * When (part of) the same page is read multiple times
804 * in succession, only mark it as accessed the first time.
805 */
806 if (prev_index != index)
807 mark_page_accessed(page);
808 prev_index = index;
809
810 /*
811 * Ok, we have the page, and it's up-to-date, so
812 * now we can copy it to user space...
813 *
814 * The actor routine returns how many bytes were actually used..
815 * NOTE! This may not be the same as how much of a user buffer
816 * we filled up (we may be padding etc), so we can only update
817 * "pos" here (the actor routine has to update the user buffer
818 * pointers and the remaining count).
819 */
820 ret = actor(desc, page, offset, nr);
821 offset += ret;
822 index += offset >> PAGE_CACHE_SHIFT;
823 offset &= ~PAGE_CACHE_MASK;
824
825 page_cache_release(page);
826 if (ret == nr && desc->count)
827 continue;
828 goto out;
829
830page_not_up_to_date:
831 /* Get exclusive access to the page ... */
832 lock_page(page);
833
834 /* Did it get unhashed before we got the lock? */
835 if (!page->mapping) {
836 unlock_page(page);
837 page_cache_release(page);
838 continue;
839 }
840
841 /* Did somebody else fill it already? */
842 if (PageUptodate(page)) {
843 unlock_page(page);
844 goto page_ok;
845 }
846
847readpage:
848 /* Start the actual read. The read will unlock the page. */
849 error = mapping->a_ops->readpage(filp, page);
850
Zach Brown994fc28c2005-12-15 14:28:17 -0800851 if (unlikely(error)) {
852 if (error == AOP_TRUNCATED_PAGE) {
853 page_cache_release(page);
854 goto find_page;
855 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800857 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858
859 if (!PageUptodate(page)) {
860 lock_page(page);
861 if (!PageUptodate(page)) {
862 if (page->mapping == NULL) {
863 /*
864 * invalidate_inode_pages got it
865 */
866 unlock_page(page);
867 page_cache_release(page);
868 goto find_page;
869 }
870 unlock_page(page);
871 error = -EIO;
872 goto readpage_error;
873 }
874 unlock_page(page);
875 }
876
877 /*
878 * i_size must be checked after we have done ->readpage.
879 *
880 * Checking i_size after the readpage allows us to calculate
881 * the correct value for "nr", which means the zero-filled
882 * part of the page is not copied back to userspace (unless
883 * another truncate extends the file - this is desired though).
884 */
885 isize = i_size_read(inode);
886 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
887 if (unlikely(!isize || index > end_index)) {
888 page_cache_release(page);
889 goto out;
890 }
891
892 /* nr is the maximum number of bytes to copy from this page */
893 nr = PAGE_CACHE_SIZE;
894 if (index == end_index) {
895 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
896 if (nr <= offset) {
897 page_cache_release(page);
898 goto out;
899 }
900 }
901 nr = nr - offset;
902 goto page_ok;
903
904readpage_error:
905 /* UHHUH! A synchronous read error occurred. Report it */
906 desc->error = error;
907 page_cache_release(page);
908 goto out;
909
910no_cached_page:
911 /*
912 * Ok, it wasn't cached, so we need to create a new
913 * page..
914 */
915 if (!cached_page) {
916 cached_page = page_cache_alloc_cold(mapping);
917 if (!cached_page) {
918 desc->error = -ENOMEM;
919 goto out;
920 }
921 }
922 error = add_to_page_cache_lru(cached_page, mapping,
923 index, GFP_KERNEL);
924 if (error) {
925 if (error == -EEXIST)
926 goto find_page;
927 desc->error = error;
928 goto out;
929 }
930 page = cached_page;
931 cached_page = NULL;
932 goto readpage;
933 }
934
935out:
936 *_ra = ra;
937
938 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
939 if (cached_page)
940 page_cache_release(cached_page);
941 if (filp)
942 file_accessed(filp);
943}
944
945EXPORT_SYMBOL(do_generic_mapping_read);
946
947int file_read_actor(read_descriptor_t *desc, struct page *page,
948 unsigned long offset, unsigned long size)
949{
950 char *kaddr;
951 unsigned long left, count = desc->count;
952
953 if (size > count)
954 size = count;
955
956 /*
957 * Faults on the destination of a read are common, so do it before
958 * taking the kmap.
959 */
960 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
961 kaddr = kmap_atomic(page, KM_USER0);
962 left = __copy_to_user_inatomic(desc->arg.buf,
963 kaddr + offset, size);
964 kunmap_atomic(kaddr, KM_USER0);
965 if (left == 0)
966 goto success;
967 }
968
969 /* Do it the slow way */
970 kaddr = kmap(page);
971 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
972 kunmap(page);
973
974 if (left) {
975 size -= left;
976 desc->error = -EFAULT;
977 }
978success:
979 desc->count = count - size;
980 desc->written += size;
981 desc->arg.buf += size;
982 return size;
983}
984
985/*
986 * This is the "read()" routine for all filesystems
987 * that can use the page cache directly.
988 */
989ssize_t
990__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
991 unsigned long nr_segs, loff_t *ppos)
992{
993 struct file *filp = iocb->ki_filp;
994 ssize_t retval;
995 unsigned long seg;
996 size_t count;
997
998 count = 0;
999 for (seg = 0; seg < nr_segs; seg++) {
1000 const struct iovec *iv = &iov[seg];
1001
1002 /*
1003 * If any segment has a negative length, or the cumulative
1004 * length ever wraps negative then return -EINVAL.
1005 */
1006 count += iv->iov_len;
1007 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1008 return -EINVAL;
1009 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1010 continue;
1011 if (seg == 0)
1012 return -EFAULT;
1013 nr_segs = seg;
1014 count -= iv->iov_len; /* This segment is no good */
1015 break;
1016 }
1017
1018 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1019 if (filp->f_flags & O_DIRECT) {
1020 loff_t pos = *ppos, size;
1021 struct address_space *mapping;
1022 struct inode *inode;
1023
1024 mapping = filp->f_mapping;
1025 inode = mapping->host;
1026 retval = 0;
1027 if (!count)
1028 goto out; /* skip atime */
1029 size = i_size_read(inode);
1030 if (pos < size) {
1031 retval = generic_file_direct_IO(READ, iocb,
1032 iov, pos, nr_segs);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001033 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 retval = -EIOCBQUEUED;
1035 if (retval > 0)
1036 *ppos = pos + retval;
1037 }
1038 file_accessed(filp);
1039 goto out;
1040 }
1041
1042 retval = 0;
1043 if (count) {
1044 for (seg = 0; seg < nr_segs; seg++) {
1045 read_descriptor_t desc;
1046
1047 desc.written = 0;
1048 desc.arg.buf = iov[seg].iov_base;
1049 desc.count = iov[seg].iov_len;
1050 if (desc.count == 0)
1051 continue;
1052 desc.error = 0;
1053 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1054 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001055 if (desc.error) {
1056 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 break;
1058 }
1059 }
1060 }
1061out:
1062 return retval;
1063}
1064
1065EXPORT_SYMBOL(__generic_file_aio_read);
1066
1067ssize_t
1068generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1069{
1070 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1071
1072 BUG_ON(iocb->ki_pos != pos);
1073 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1074}
1075
1076EXPORT_SYMBOL(generic_file_aio_read);
1077
1078ssize_t
1079generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1080{
1081 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1082 struct kiocb kiocb;
1083 ssize_t ret;
1084
1085 init_sync_kiocb(&kiocb, filp);
1086 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1087 if (-EIOCBQUEUED == ret)
1088 ret = wait_on_sync_kiocb(&kiocb);
1089 return ret;
1090}
1091
1092EXPORT_SYMBOL(generic_file_read);
1093
1094int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1095{
1096 ssize_t written;
1097 unsigned long count = desc->count;
1098 struct file *file = desc->arg.data;
1099
1100 if (size > count)
1101 size = count;
1102
1103 written = file->f_op->sendpage(file, page, offset,
1104 size, &file->f_pos, size<count);
1105 if (written < 0) {
1106 desc->error = written;
1107 written = 0;
1108 }
1109 desc->count = count - written;
1110 desc->written += written;
1111 return written;
1112}
1113
1114ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1115 size_t count, read_actor_t actor, void *target)
1116{
1117 read_descriptor_t desc;
1118
1119 if (!count)
1120 return 0;
1121
1122 desc.written = 0;
1123 desc.count = count;
1124 desc.arg.data = target;
1125 desc.error = 0;
1126
1127 do_generic_file_read(in_file, ppos, &desc, actor);
1128 if (desc.written)
1129 return desc.written;
1130 return desc.error;
1131}
1132
1133EXPORT_SYMBOL(generic_file_sendfile);
1134
1135static ssize_t
1136do_readahead(struct address_space *mapping, struct file *filp,
1137 unsigned long index, unsigned long nr)
1138{
1139 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1140 return -EINVAL;
1141
1142 force_page_cache_readahead(mapping, filp, index,
1143 max_sane_readahead(nr));
1144 return 0;
1145}
1146
1147asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1148{
1149 ssize_t ret;
1150 struct file *file;
1151
1152 ret = -EBADF;
1153 file = fget(fd);
1154 if (file) {
1155 if (file->f_mode & FMODE_READ) {
1156 struct address_space *mapping = file->f_mapping;
1157 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1158 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1159 unsigned long len = end - start + 1;
1160 ret = do_readahead(mapping, file, start, len);
1161 }
1162 fput(file);
1163 }
1164 return ret;
1165}
1166
1167#ifdef CONFIG_MMU
1168/*
1169 * This adds the requested page to the page cache if it isn't already there,
1170 * and schedules an I/O to read in its contents from disk.
1171 */
1172static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1173static int fastcall page_cache_read(struct file * file, unsigned long offset)
1174{
1175 struct address_space *mapping = file->f_mapping;
1176 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001177 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178
Zach Brown994fc28c2005-12-15 14:28:17 -08001179 do {
1180 page = page_cache_alloc_cold(mapping);
1181 if (!page)
1182 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183
Zach Brown994fc28c2005-12-15 14:28:17 -08001184 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1185 if (ret == 0)
1186 ret = mapping->a_ops->readpage(file, page);
1187 else if (ret == -EEXIST)
1188 ret = 0; /* losing race to add is OK */
1189
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191
Zach Brown994fc28c2005-12-15 14:28:17 -08001192 } while (ret == AOP_TRUNCATED_PAGE);
1193
1194 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195}
1196
1197#define MMAP_LOTSAMISS (100)
1198
1199/*
1200 * filemap_nopage() is invoked via the vma operations vector for a
1201 * mapped memory region to read in file data during a page fault.
1202 *
1203 * The goto's are kind of ugly, but this streamlines the normal case of having
1204 * it in the page cache, and handles the special cases reasonably without
1205 * having a lot of duplicated code.
1206 */
1207struct page *filemap_nopage(struct vm_area_struct *area,
1208 unsigned long address, int *type)
1209{
1210 int error;
1211 struct file *file = area->vm_file;
1212 struct address_space *mapping = file->f_mapping;
1213 struct file_ra_state *ra = &file->f_ra;
1214 struct inode *inode = mapping->host;
1215 struct page *page;
1216 unsigned long size, pgoff;
1217 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1218
1219 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1220
1221retry_all:
1222 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1223 if (pgoff >= size)
1224 goto outside_data_content;
1225
1226 /* If we don't want any read-ahead, don't bother */
1227 if (VM_RandomReadHint(area))
1228 goto no_cached_page;
1229
1230 /*
1231 * The readahead code wants to be told about each and every page
1232 * so it can build and shrink its windows appropriately
1233 *
1234 * For sequential accesses, we use the generic readahead logic.
1235 */
1236 if (VM_SequentialReadHint(area))
1237 page_cache_readahead(mapping, ra, file, pgoff, 1);
1238
1239 /*
1240 * Do we have something in the page cache already?
1241 */
1242retry_find:
1243 page = find_get_page(mapping, pgoff);
1244 if (!page) {
1245 unsigned long ra_pages;
1246
1247 if (VM_SequentialReadHint(area)) {
1248 handle_ra_miss(mapping, ra, pgoff);
1249 goto no_cached_page;
1250 }
1251 ra->mmap_miss++;
1252
1253 /*
1254 * Do we miss much more than hit in this file? If so,
1255 * stop bothering with read-ahead. It will only hurt.
1256 */
1257 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1258 goto no_cached_page;
1259
1260 /*
1261 * To keep the pgmajfault counter straight, we need to
1262 * check did_readaround, as this is an inner loop.
1263 */
1264 if (!did_readaround) {
1265 majmin = VM_FAULT_MAJOR;
1266 inc_page_state(pgmajfault);
1267 }
1268 did_readaround = 1;
1269 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1270 if (ra_pages) {
1271 pgoff_t start = 0;
1272
1273 if (pgoff > ra_pages / 2)
1274 start = pgoff - ra_pages / 2;
1275 do_page_cache_readahead(mapping, file, start, ra_pages);
1276 }
1277 page = find_get_page(mapping, pgoff);
1278 if (!page)
1279 goto no_cached_page;
1280 }
1281
1282 if (!did_readaround)
1283 ra->mmap_hit++;
1284
1285 /*
1286 * Ok, found a page in the page cache, now we need to check
1287 * that it's up-to-date.
1288 */
1289 if (!PageUptodate(page))
1290 goto page_not_uptodate;
1291
1292success:
1293 /*
1294 * Found the page and have a reference on it.
1295 */
1296 mark_page_accessed(page);
1297 if (type)
1298 *type = majmin;
1299 return page;
1300
1301outside_data_content:
1302 /*
1303 * An external ptracer can access pages that normally aren't
1304 * accessible..
1305 */
1306 if (area->vm_mm == current->mm)
1307 return NULL;
1308 /* Fall through to the non-read-ahead case */
1309no_cached_page:
1310 /*
1311 * We're only likely to ever get here if MADV_RANDOM is in
1312 * effect.
1313 */
1314 error = page_cache_read(file, pgoff);
1315 grab_swap_token();
1316
1317 /*
1318 * The page we want has now been added to the page cache.
1319 * In the unlikely event that someone removed it in the
1320 * meantime, we'll just come back here and read it again.
1321 */
1322 if (error >= 0)
1323 goto retry_find;
1324
1325 /*
1326 * An error return from page_cache_read can result if the
1327 * system is low on memory, or a problem occurs while trying
1328 * to schedule I/O.
1329 */
1330 if (error == -ENOMEM)
1331 return NOPAGE_OOM;
1332 return NULL;
1333
1334page_not_uptodate:
1335 if (!did_readaround) {
1336 majmin = VM_FAULT_MAJOR;
1337 inc_page_state(pgmajfault);
1338 }
1339 lock_page(page);
1340
1341 /* Did it get unhashed while we waited for it? */
1342 if (!page->mapping) {
1343 unlock_page(page);
1344 page_cache_release(page);
1345 goto retry_all;
1346 }
1347
1348 /* Did somebody else get it up-to-date? */
1349 if (PageUptodate(page)) {
1350 unlock_page(page);
1351 goto success;
1352 }
1353
Zach Brown994fc28c2005-12-15 14:28:17 -08001354 error = mapping->a_ops->readpage(file, page);
1355 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356 wait_on_page_locked(page);
1357 if (PageUptodate(page))
1358 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001359 } else if (error == AOP_TRUNCATED_PAGE) {
1360 page_cache_release(page);
1361 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 }
1363
1364 /*
1365 * Umm, take care of errors if the page isn't up-to-date.
1366 * Try to re-read it _once_. We do this synchronously,
1367 * because there really aren't any performance issues here
1368 * and we need to check for errors.
1369 */
1370 lock_page(page);
1371
1372 /* Somebody truncated the page on us? */
1373 if (!page->mapping) {
1374 unlock_page(page);
1375 page_cache_release(page);
1376 goto retry_all;
1377 }
1378
1379 /* Somebody else successfully read it in? */
1380 if (PageUptodate(page)) {
1381 unlock_page(page);
1382 goto success;
1383 }
1384 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001385 error = mapping->a_ops->readpage(file, page);
1386 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 wait_on_page_locked(page);
1388 if (PageUptodate(page))
1389 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001390 } else if (error == AOP_TRUNCATED_PAGE) {
1391 page_cache_release(page);
1392 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001393 }
1394
1395 /*
1396 * Things didn't work out. Return zero to tell the
1397 * mm layer so, possibly freeing the page cache page first.
1398 */
1399 page_cache_release(page);
1400 return NULL;
1401}
1402
1403EXPORT_SYMBOL(filemap_nopage);
1404
1405static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1406 int nonblock)
1407{
1408 struct address_space *mapping = file->f_mapping;
1409 struct page *page;
1410 int error;
1411
1412 /*
1413 * Do we have something in the page cache already?
1414 */
1415retry_find:
1416 page = find_get_page(mapping, pgoff);
1417 if (!page) {
1418 if (nonblock)
1419 return NULL;
1420 goto no_cached_page;
1421 }
1422
1423 /*
1424 * Ok, found a page in the page cache, now we need to check
1425 * that it's up-to-date.
1426 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001427 if (!PageUptodate(page)) {
1428 if (nonblock) {
1429 page_cache_release(page);
1430 return NULL;
1431 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001433 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434
1435success:
1436 /*
1437 * Found the page and have a reference on it.
1438 */
1439 mark_page_accessed(page);
1440 return page;
1441
1442no_cached_page:
1443 error = page_cache_read(file, pgoff);
1444
1445 /*
1446 * The page we want has now been added to the page cache.
1447 * In the unlikely event that someone removed it in the
1448 * meantime, we'll just come back here and read it again.
1449 */
1450 if (error >= 0)
1451 goto retry_find;
1452
1453 /*
1454 * An error return from page_cache_read can result if the
1455 * system is low on memory, or a problem occurs while trying
1456 * to schedule I/O.
1457 */
1458 return NULL;
1459
1460page_not_uptodate:
1461 lock_page(page);
1462
1463 /* Did it get unhashed while we waited for it? */
1464 if (!page->mapping) {
1465 unlock_page(page);
1466 goto err;
1467 }
1468
1469 /* Did somebody else get it up-to-date? */
1470 if (PageUptodate(page)) {
1471 unlock_page(page);
1472 goto success;
1473 }
1474
Zach Brown994fc28c2005-12-15 14:28:17 -08001475 error = mapping->a_ops->readpage(file, page);
1476 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 wait_on_page_locked(page);
1478 if (PageUptodate(page))
1479 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001480 } else if (error == AOP_TRUNCATED_PAGE) {
1481 page_cache_release(page);
1482 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483 }
1484
1485 /*
1486 * Umm, take care of errors if the page isn't up-to-date.
1487 * Try to re-read it _once_. We do this synchronously,
1488 * because there really aren't any performance issues here
1489 * and we need to check for errors.
1490 */
1491 lock_page(page);
1492
1493 /* Somebody truncated the page on us? */
1494 if (!page->mapping) {
1495 unlock_page(page);
1496 goto err;
1497 }
1498 /* Somebody else successfully read it in? */
1499 if (PageUptodate(page)) {
1500 unlock_page(page);
1501 goto success;
1502 }
1503
1504 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001505 error = mapping->a_ops->readpage(file, page);
1506 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 wait_on_page_locked(page);
1508 if (PageUptodate(page))
1509 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001510 } else if (error == AOP_TRUNCATED_PAGE) {
1511 page_cache_release(page);
1512 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513 }
1514
1515 /*
1516 * Things didn't work out. Return zero to tell the
1517 * mm layer so, possibly freeing the page cache page first.
1518 */
1519err:
1520 page_cache_release(page);
1521
1522 return NULL;
1523}
1524
1525int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1526 unsigned long len, pgprot_t prot, unsigned long pgoff,
1527 int nonblock)
1528{
1529 struct file *file = vma->vm_file;
1530 struct address_space *mapping = file->f_mapping;
1531 struct inode *inode = mapping->host;
1532 unsigned long size;
1533 struct mm_struct *mm = vma->vm_mm;
1534 struct page *page;
1535 int err;
1536
1537 if (!nonblock)
1538 force_page_cache_readahead(mapping, vma->vm_file,
1539 pgoff, len >> PAGE_CACHE_SHIFT);
1540
1541repeat:
1542 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1543 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1544 return -EINVAL;
1545
1546 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001547
1548 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1549 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 if (!page && !nonblock)
1551 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001552
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 if (page) {
1554 err = install_page(mm, vma, addr, page, prot);
1555 if (err) {
1556 page_cache_release(page);
1557 return err;
1558 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001559 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001560 /* No page was found just because we can't read it in now (being
1561 * here implies nonblock != 0), but the page may exist, so set
1562 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563 err = install_file_pte(mm, vma, addr, pgoff, prot);
1564 if (err)
1565 return err;
1566 }
1567
1568 len -= PAGE_SIZE;
1569 addr += PAGE_SIZE;
1570 pgoff++;
1571 if (len)
1572 goto repeat;
1573
1574 return 0;
1575}
Nikita Danilovb1459462005-10-29 18:17:02 -07001576EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577
1578struct vm_operations_struct generic_file_vm_ops = {
1579 .nopage = filemap_nopage,
1580 .populate = filemap_populate,
1581};
1582
1583/* This is used for a general mmap of a disk file */
1584
1585int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1586{
1587 struct address_space *mapping = file->f_mapping;
1588
1589 if (!mapping->a_ops->readpage)
1590 return -ENOEXEC;
1591 file_accessed(file);
1592 vma->vm_ops = &generic_file_vm_ops;
1593 return 0;
1594}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595
1596/*
1597 * This is for filesystems which do not implement ->writepage.
1598 */
1599int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1600{
1601 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1602 return -EINVAL;
1603 return generic_file_mmap(file, vma);
1604}
1605#else
1606int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1607{
1608 return -ENOSYS;
1609}
1610int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1611{
1612 return -ENOSYS;
1613}
1614#endif /* CONFIG_MMU */
1615
1616EXPORT_SYMBOL(generic_file_mmap);
1617EXPORT_SYMBOL(generic_file_readonly_mmap);
1618
1619static inline struct page *__read_cache_page(struct address_space *mapping,
1620 unsigned long index,
1621 int (*filler)(void *,struct page*),
1622 void *data)
1623{
1624 struct page *page, *cached_page = NULL;
1625 int err;
1626repeat:
1627 page = find_get_page(mapping, index);
1628 if (!page) {
1629 if (!cached_page) {
1630 cached_page = page_cache_alloc_cold(mapping);
1631 if (!cached_page)
1632 return ERR_PTR(-ENOMEM);
1633 }
1634 err = add_to_page_cache_lru(cached_page, mapping,
1635 index, GFP_KERNEL);
1636 if (err == -EEXIST)
1637 goto repeat;
1638 if (err < 0) {
1639 /* Presumably ENOMEM for radix tree node */
1640 page_cache_release(cached_page);
1641 return ERR_PTR(err);
1642 }
1643 page = cached_page;
1644 cached_page = NULL;
1645 err = filler(data, page);
1646 if (err < 0) {
1647 page_cache_release(page);
1648 page = ERR_PTR(err);
1649 }
1650 }
1651 if (cached_page)
1652 page_cache_release(cached_page);
1653 return page;
1654}
1655
1656/*
1657 * Read into the page cache. If a page already exists,
1658 * and PageUptodate() is not set, try to fill the page.
1659 */
1660struct page *read_cache_page(struct address_space *mapping,
1661 unsigned long index,
1662 int (*filler)(void *,struct page*),
1663 void *data)
1664{
1665 struct page *page;
1666 int err;
1667
1668retry:
1669 page = __read_cache_page(mapping, index, filler, data);
1670 if (IS_ERR(page))
1671 goto out;
1672 mark_page_accessed(page);
1673 if (PageUptodate(page))
1674 goto out;
1675
1676 lock_page(page);
1677 if (!page->mapping) {
1678 unlock_page(page);
1679 page_cache_release(page);
1680 goto retry;
1681 }
1682 if (PageUptodate(page)) {
1683 unlock_page(page);
1684 goto out;
1685 }
1686 err = filler(data, page);
1687 if (err < 0) {
1688 page_cache_release(page);
1689 page = ERR_PTR(err);
1690 }
1691 out:
1692 return page;
1693}
1694
1695EXPORT_SYMBOL(read_cache_page);
1696
1697/*
1698 * If the page was newly created, increment its refcount and add it to the
1699 * caller's lru-buffering pagevec. This function is specifically for
1700 * generic_file_write().
1701 */
1702static inline struct page *
1703__grab_cache_page(struct address_space *mapping, unsigned long index,
1704 struct page **cached_page, struct pagevec *lru_pvec)
1705{
1706 int err;
1707 struct page *page;
1708repeat:
1709 page = find_lock_page(mapping, index);
1710 if (!page) {
1711 if (!*cached_page) {
1712 *cached_page = page_cache_alloc(mapping);
1713 if (!*cached_page)
1714 return NULL;
1715 }
1716 err = add_to_page_cache(*cached_page, mapping,
1717 index, GFP_KERNEL);
1718 if (err == -EEXIST)
1719 goto repeat;
1720 if (err == 0) {
1721 page = *cached_page;
1722 page_cache_get(page);
1723 if (!pagevec_add(lru_pvec, page))
1724 __pagevec_lru_add(lru_pvec);
1725 *cached_page = NULL;
1726 }
1727 }
1728 return page;
1729}
1730
1731/*
1732 * The logic we want is
1733 *
1734 * if suid or (sgid and xgrp)
1735 * remove privs
1736 */
1737int remove_suid(struct dentry *dentry)
1738{
1739 mode_t mode = dentry->d_inode->i_mode;
1740 int kill = 0;
1741 int result = 0;
1742
1743 /* suid always must be killed */
1744 if (unlikely(mode & S_ISUID))
1745 kill = ATTR_KILL_SUID;
1746
1747 /*
1748 * sgid without any exec bits is just a mandatory locking mark; leave
1749 * it alone. If some exec bits are set, it's a real sgid; kill it.
1750 */
1751 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1752 kill |= ATTR_KILL_SGID;
1753
1754 if (unlikely(kill && !capable(CAP_FSETID))) {
1755 struct iattr newattrs;
1756
1757 newattrs.ia_valid = ATTR_FORCE | kill;
1758 result = notify_change(dentry, &newattrs);
1759 }
1760 return result;
1761}
1762EXPORT_SYMBOL(remove_suid);
1763
Carsten Otteceffc072005-06-23 22:05:25 -07001764size_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765__filemap_copy_from_user_iovec(char *vaddr,
1766 const struct iovec *iov, size_t base, size_t bytes)
1767{
1768 size_t copied = 0, left = 0;
1769
1770 while (bytes) {
1771 char __user *buf = iov->iov_base + base;
1772 int copy = min(bytes, iov->iov_len - base);
1773
1774 base = 0;
1775 left = __copy_from_user_inatomic(vaddr, buf, copy);
1776 copied += copy;
1777 bytes -= copy;
1778 vaddr += copy;
1779 iov++;
1780
1781 if (unlikely(left)) {
1782 /* zero the rest of the target like __copy_from_user */
1783 if (bytes)
1784 memset(vaddr, 0, bytes);
1785 break;
1786 }
1787 }
1788 return copied - left;
1789}
1790
1791/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 * Performs necessary checks before doing a write
1793 *
1794 * Can adjust writing position aor amount of bytes to write.
1795 * Returns appropriate error code that caller should return or
1796 * zero in case that write should be allowed.
1797 */
1798inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1799{
1800 struct inode *inode = file->f_mapping->host;
1801 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1802
1803 if (unlikely(*pos < 0))
1804 return -EINVAL;
1805
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 if (!isblk) {
1807 /* FIXME: this is for backwards compatibility with 2.4 */
1808 if (file->f_flags & O_APPEND)
1809 *pos = i_size_read(inode);
1810
1811 if (limit != RLIM_INFINITY) {
1812 if (*pos >= limit) {
1813 send_sig(SIGXFSZ, current, 0);
1814 return -EFBIG;
1815 }
1816 if (*count > limit - (typeof(limit))*pos) {
1817 *count = limit - (typeof(limit))*pos;
1818 }
1819 }
1820 }
1821
1822 /*
1823 * LFS rule
1824 */
1825 if (unlikely(*pos + *count > MAX_NON_LFS &&
1826 !(file->f_flags & O_LARGEFILE))) {
1827 if (*pos >= MAX_NON_LFS) {
1828 send_sig(SIGXFSZ, current, 0);
1829 return -EFBIG;
1830 }
1831 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1832 *count = MAX_NON_LFS - (unsigned long)*pos;
1833 }
1834 }
1835
1836 /*
1837 * Are we about to exceed the fs block limit ?
1838 *
1839 * If we have written data it becomes a short write. If we have
1840 * exceeded without writing data we send a signal and return EFBIG.
1841 * Linus frestrict idea will clean these up nicely..
1842 */
1843 if (likely(!isblk)) {
1844 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1845 if (*count || *pos > inode->i_sb->s_maxbytes) {
1846 send_sig(SIGXFSZ, current, 0);
1847 return -EFBIG;
1848 }
1849 /* zero-length writes at ->s_maxbytes are OK */
1850 }
1851
1852 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1853 *count = inode->i_sb->s_maxbytes - *pos;
1854 } else {
1855 loff_t isize;
1856 if (bdev_read_only(I_BDEV(inode)))
1857 return -EPERM;
1858 isize = i_size_read(inode);
1859 if (*pos >= isize) {
1860 if (*count || *pos > isize)
1861 return -ENOSPC;
1862 }
1863
1864 if (*pos + *count > isize)
1865 *count = isize - *pos;
1866 }
1867 return 0;
1868}
1869EXPORT_SYMBOL(generic_write_checks);
1870
1871ssize_t
1872generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1873 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1874 size_t count, size_t ocount)
1875{
1876 struct file *file = iocb->ki_filp;
1877 struct address_space *mapping = file->f_mapping;
1878 struct inode *inode = mapping->host;
1879 ssize_t written;
1880
1881 if (count != ocount)
1882 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1883
1884 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1885 if (written > 0) {
1886 loff_t end = pos + written;
1887 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1888 i_size_write(inode, end);
1889 mark_inode_dirty(inode);
1890 }
1891 *ppos = end;
1892 }
1893
1894 /*
1895 * Sync the fs metadata but not the minor inode changes and
1896 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001897 * i_mutex is held, which protects generic_osync_inode() from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898 * livelocking.
1899 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07001900 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1901 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1902 if (err < 0)
1903 written = err;
1904 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905 if (written == count && !is_sync_kiocb(iocb))
1906 written = -EIOCBQUEUED;
1907 return written;
1908}
1909EXPORT_SYMBOL(generic_file_direct_write);
1910
1911ssize_t
1912generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1913 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1914 size_t count, ssize_t written)
1915{
1916 struct file *file = iocb->ki_filp;
1917 struct address_space * mapping = file->f_mapping;
1918 struct address_space_operations *a_ops = mapping->a_ops;
1919 struct inode *inode = mapping->host;
1920 long status = 0;
1921 struct page *page;
1922 struct page *cached_page = NULL;
1923 size_t bytes;
1924 struct pagevec lru_pvec;
1925 const struct iovec *cur_iov = iov; /* current iovec */
1926 size_t iov_base = 0; /* offset in the current iovec */
1927 char __user *buf;
1928
1929 pagevec_init(&lru_pvec, 0);
1930
1931 /*
1932 * handle partial DIO write. Adjust cur_iov if needed.
1933 */
1934 if (likely(nr_segs == 1))
1935 buf = iov->iov_base + written;
1936 else {
1937 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001938 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 }
1940
1941 do {
1942 unsigned long index;
1943 unsigned long offset;
Martin Schwidefskya5117182005-06-06 13:35:54 -07001944 unsigned long maxlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 size_t copied;
1946
1947 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1948 index = pos >> PAGE_CACHE_SHIFT;
1949 bytes = PAGE_CACHE_SIZE - offset;
1950 if (bytes > count)
1951 bytes = count;
1952
1953 /*
1954 * Bring in the user page that we will copy from _first_.
1955 * Otherwise there's a nasty deadlock on copying from the
1956 * same page as we're writing to, without it being marked
1957 * up-to-date.
1958 */
Martin Schwidefskya5117182005-06-06 13:35:54 -07001959 maxlen = cur_iov->iov_len - iov_base;
1960 if (maxlen > bytes)
1961 maxlen = bytes;
1962 fault_in_pages_readable(buf, maxlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963
1964 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1965 if (!page) {
1966 status = -ENOMEM;
1967 break;
1968 }
1969
1970 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1971 if (unlikely(status)) {
1972 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08001973
1974 if (status != AOP_TRUNCATED_PAGE)
1975 unlock_page(page);
1976 page_cache_release(page);
1977 if (status == AOP_TRUNCATED_PAGE)
1978 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 /*
1980 * prepare_write() may have instantiated a few blocks
1981 * outside i_size. Trim these off again.
1982 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001983 if (pos + bytes > isize)
1984 vmtruncate(inode, isize);
1985 break;
1986 }
1987 if (likely(nr_segs == 1))
1988 copied = filemap_copy_from_user(page, offset,
1989 buf, bytes);
1990 else
1991 copied = filemap_copy_from_user_iovec(page, offset,
1992 cur_iov, iov_base, bytes);
1993 flush_dcache_page(page);
1994 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08001995 if (status == AOP_TRUNCATED_PAGE) {
1996 page_cache_release(page);
1997 continue;
1998 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999 if (likely(copied > 0)) {
2000 if (!status)
2001 status = copied;
2002
2003 if (status >= 0) {
2004 written += status;
2005 count -= status;
2006 pos += status;
2007 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002008 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 filemap_set_next_iovec(&cur_iov,
2010 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002011 if (count)
2012 buf = cur_iov->iov_base +
2013 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002014 } else {
2015 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002016 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 }
2018 }
2019 if (unlikely(copied != bytes))
2020 if (status >= 0)
2021 status = -EFAULT;
2022 unlock_page(page);
2023 mark_page_accessed(page);
2024 page_cache_release(page);
2025 if (status < 0)
2026 break;
2027 balance_dirty_pages_ratelimited(mapping);
2028 cond_resched();
2029 } while (count);
2030 *ppos = pos;
2031
2032 if (cached_page)
2033 page_cache_release(cached_page);
2034
2035 /*
2036 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2037 */
2038 if (likely(status >= 0)) {
2039 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2040 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2041 status = generic_osync_inode(inode, mapping,
2042 OSYNC_METADATA|OSYNC_DATA);
2043 }
2044 }
2045
2046 /*
2047 * If we get here for O_DIRECT writes then we must have fallen through
2048 * to buffered writes (block instantiation inside i_size). So we sync
2049 * the file data here, to try to honour O_DIRECT expectations.
2050 */
2051 if (unlikely(file->f_flags & O_DIRECT) && written)
2052 status = filemap_write_and_wait(mapping);
2053
2054 pagevec_lru_add(&lru_pvec);
2055 return written ? written : status;
2056}
2057EXPORT_SYMBOL(generic_file_buffered_write);
2058
Adrian Bunk5ce78522005-09-10 00:26:28 -07002059static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2061 unsigned long nr_segs, loff_t *ppos)
2062{
2063 struct file *file = iocb->ki_filp;
2064 struct address_space * mapping = file->f_mapping;
2065 size_t ocount; /* original count */
2066 size_t count; /* after file limit checks */
2067 struct inode *inode = mapping->host;
2068 unsigned long seg;
2069 loff_t pos;
2070 ssize_t written;
2071 ssize_t err;
2072
2073 ocount = 0;
2074 for (seg = 0; seg < nr_segs; seg++) {
2075 const struct iovec *iv = &iov[seg];
2076
2077 /*
2078 * If any segment has a negative length, or the cumulative
2079 * length ever wraps negative then return -EINVAL.
2080 */
2081 ocount += iv->iov_len;
2082 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2083 return -EINVAL;
2084 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2085 continue;
2086 if (seg == 0)
2087 return -EFAULT;
2088 nr_segs = seg;
2089 ocount -= iv->iov_len; /* This segment is no good */
2090 break;
2091 }
2092
2093 count = ocount;
2094 pos = *ppos;
2095
2096 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2097
2098 /* We can write back this queue in page reclaim */
2099 current->backing_dev_info = mapping->backing_dev_info;
2100 written = 0;
2101
2102 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2103 if (err)
2104 goto out;
2105
2106 if (count == 0)
2107 goto out;
2108
2109 err = remove_suid(file->f_dentry);
2110 if (err)
2111 goto out;
2112
Christoph Hellwig870f4812006-01-09 20:52:01 -08002113 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002114
2115 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2116 if (unlikely(file->f_flags & O_DIRECT)) {
2117 written = generic_file_direct_write(iocb, iov,
2118 &nr_segs, pos, ppos, count, ocount);
2119 if (written < 0 || written == count)
2120 goto out;
2121 /*
2122 * direct-io write to a hole: fall through to buffered I/O
2123 * for completing the rest of the request.
2124 */
2125 pos += written;
2126 count -= written;
2127 }
2128
2129 written = generic_file_buffered_write(iocb, iov, nr_segs,
2130 pos, ppos, count, written);
2131out:
2132 current->backing_dev_info = NULL;
2133 return written ? written : err;
2134}
2135EXPORT_SYMBOL(generic_file_aio_write_nolock);
2136
2137ssize_t
2138generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2139 unsigned long nr_segs, loff_t *ppos)
2140{
2141 struct file *file = iocb->ki_filp;
2142 struct address_space *mapping = file->f_mapping;
2143 struct inode *inode = mapping->host;
2144 ssize_t ret;
2145 loff_t pos = *ppos;
2146
2147 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2148
2149 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2150 int err;
2151
2152 err = sync_page_range_nolock(inode, mapping, pos, ret);
2153 if (err < 0)
2154 ret = err;
2155 }
2156 return ret;
2157}
2158
Adrian Bunk5ce78522005-09-10 00:26:28 -07002159static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002160__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2161 unsigned long nr_segs, loff_t *ppos)
2162{
2163 struct kiocb kiocb;
2164 ssize_t ret;
2165
2166 init_sync_kiocb(&kiocb, file);
2167 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2168 if (ret == -EIOCBQUEUED)
2169 ret = wait_on_sync_kiocb(&kiocb);
2170 return ret;
2171}
2172
2173ssize_t
2174generic_file_write_nolock(struct file *file, const struct iovec *iov,
2175 unsigned long nr_segs, loff_t *ppos)
2176{
2177 struct kiocb kiocb;
2178 ssize_t ret;
2179
2180 init_sync_kiocb(&kiocb, file);
2181 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2182 if (-EIOCBQUEUED == ret)
2183 ret = wait_on_sync_kiocb(&kiocb);
2184 return ret;
2185}
2186EXPORT_SYMBOL(generic_file_write_nolock);
2187
2188ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2189 size_t count, loff_t pos)
2190{
2191 struct file *file = iocb->ki_filp;
2192 struct address_space *mapping = file->f_mapping;
2193 struct inode *inode = mapping->host;
2194 ssize_t ret;
2195 struct iovec local_iov = { .iov_base = (void __user *)buf,
2196 .iov_len = count };
2197
2198 BUG_ON(iocb->ki_pos != pos);
2199
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002200 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2202 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002203 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204
2205 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2206 ssize_t err;
2207
2208 err = sync_page_range(inode, mapping, pos, ret);
2209 if (err < 0)
2210 ret = err;
2211 }
2212 return ret;
2213}
2214EXPORT_SYMBOL(generic_file_aio_write);
2215
2216ssize_t generic_file_write(struct file *file, const char __user *buf,
2217 size_t count, loff_t *ppos)
2218{
2219 struct address_space *mapping = file->f_mapping;
2220 struct inode *inode = mapping->host;
2221 ssize_t ret;
2222 struct iovec local_iov = { .iov_base = (void __user *)buf,
2223 .iov_len = count };
2224
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002225 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002226 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002227 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228
2229 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2230 ssize_t err;
2231
2232 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2233 if (err < 0)
2234 ret = err;
2235 }
2236 return ret;
2237}
2238EXPORT_SYMBOL(generic_file_write);
2239
2240ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2241 unsigned long nr_segs, loff_t *ppos)
2242{
2243 struct kiocb kiocb;
2244 ssize_t ret;
2245
2246 init_sync_kiocb(&kiocb, filp);
2247 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2248 if (-EIOCBQUEUED == ret)
2249 ret = wait_on_sync_kiocb(&kiocb);
2250 return ret;
2251}
2252EXPORT_SYMBOL(generic_file_readv);
2253
2254ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2255 unsigned long nr_segs, loff_t *ppos)
2256{
2257 struct address_space *mapping = file->f_mapping;
2258 struct inode *inode = mapping->host;
2259 ssize_t ret;
2260
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002261 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002263 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264
2265 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2266 int err;
2267
2268 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2269 if (err < 0)
2270 ret = err;
2271 }
2272 return ret;
2273}
2274EXPORT_SYMBOL(generic_file_writev);
2275
2276/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002277 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278 * went wrong during pagecache shootdown.
2279 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002280static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2282 loff_t offset, unsigned long nr_segs)
2283{
2284 struct file *file = iocb->ki_filp;
2285 struct address_space *mapping = file->f_mapping;
2286 ssize_t retval;
2287 size_t write_len = 0;
2288
2289 /*
2290 * If it's a write, unmap all mmappings of the file up-front. This
2291 * will cause any pte dirty bits to be propagated into the pageframes
2292 * for the subsequent filemap_write_and_wait().
2293 */
2294 if (rw == WRITE) {
2295 write_len = iov_length(iov, nr_segs);
2296 if (mapping_mapped(mapping))
2297 unmap_mapping_range(mapping, offset, write_len, 0);
2298 }
2299
2300 retval = filemap_write_and_wait(mapping);
2301 if (retval == 0) {
2302 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2303 offset, nr_segs);
2304 if (rw == WRITE && mapping->nrpages) {
2305 pgoff_t end = (offset + write_len - 1)
2306 >> PAGE_CACHE_SHIFT;
2307 int err = invalidate_inode_pages2_range(mapping,
2308 offset >> PAGE_CACHE_SHIFT, end);
2309 if (err)
2310 retval = err;
2311 }
2312 }
2313 return retval;
2314}