blob: 96de772be487b7c8e6df4e591bd2f3cf9b8647ab [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 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080064 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 * ->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
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080076 * ->i_mutex (msync)
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080078 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 * ->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
Andi Kleen07808b72005-11-05 17:25:53 +0100137 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138
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 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800279 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 * it is otherwise livelockable.
281 */
282int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800283 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284{
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) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800293 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800295 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 }
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/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800304 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 * as it forces O_SYNC writers to different parts of the same file
306 * to be serialised right until io completion.
307 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800308int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
309 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310{
311 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
312 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
313 int ret;
314
315 if (!mapping_cap_writeback_dirty(mapping) || !count)
316 return 0;
317 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
318 if (ret == 0)
319 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
320 if (ret == 0)
321 ret = wait_on_page_writeback_range(mapping, start, end);
322 return ret;
323}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800324EXPORT_SYMBOL(sync_page_range_nolock);
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{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800346 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347
348 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800349 err = filemap_fdatawrite(mapping);
350 /*
351 * Even if the above returned error, the pages may be
352 * written partially (e.g. -ENOSPC), so we wait for it.
353 * But the -EIO is special case, it may indicate the worst
354 * thing (e.g. bug) happened, so we avoid waiting for it.
355 */
356 if (err != -EIO) {
357 int err2 = filemap_fdatawait(mapping);
358 if (!err)
359 err = err2;
360 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800362 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800364EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
366int filemap_write_and_wait_range(struct address_space *mapping,
367 loff_t lstart, loff_t lend)
368{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800369 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
371 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800372 err = __filemap_fdatawrite_range(mapping, lstart, lend,
373 WB_SYNC_ALL);
374 /* See comment of filemap_write_and_wait() */
375 if (err != -EIO) {
376 int err2 = wait_on_page_writeback_range(mapping,
377 lstart >> PAGE_CACHE_SHIFT,
378 lend >> PAGE_CACHE_SHIFT);
379 if (!err)
380 err = err2;
381 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800383 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384}
385
386/*
387 * This function is used to add newly allocated pagecache pages:
388 * the page is new, so we can just run SetPageLocked() against it.
389 * The other page state flags were set by rmqueue().
390 *
391 * This function does not add the page to the LRU. The caller must do that.
392 */
393int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400394 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395{
396 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
397
398 if (error == 0) {
399 write_lock_irq(&mapping->tree_lock);
400 error = radix_tree_insert(&mapping->page_tree, offset, page);
401 if (!error) {
402 page_cache_get(page);
403 SetPageLocked(page);
404 page->mapping = mapping;
405 page->index = offset;
406 mapping->nrpages++;
407 pagecache_acct(1);
408 }
409 write_unlock_irq(&mapping->tree_lock);
410 radix_tree_preload_end();
411 }
412 return error;
413}
414
415EXPORT_SYMBOL(add_to_page_cache);
416
417int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400418 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419{
420 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
421 if (ret == 0)
422 lru_cache_add(page);
423 return ret;
424}
425
426/*
427 * In order to wait for pages to become available there must be
428 * waitqueues associated with pages. By using a hash table of
429 * waitqueues where the bucket discipline is to maintain all
430 * waiters on the same queue and wake all when any of the pages
431 * become available, and for the woken contexts to check to be
432 * sure the appropriate page became available, this saves space
433 * at a cost of "thundering herd" phenomena during rare hash
434 * collisions.
435 */
436static wait_queue_head_t *page_waitqueue(struct page *page)
437{
438 const struct zone *zone = page_zone(page);
439
440 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
441}
442
443static inline void wake_up_page(struct page *page, int bit)
444{
445 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
446}
447
448void fastcall wait_on_page_bit(struct page *page, int bit_nr)
449{
450 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
451
452 if (test_bit(bit_nr, &page->flags))
453 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
454 TASK_UNINTERRUPTIBLE);
455}
456EXPORT_SYMBOL(wait_on_page_bit);
457
458/**
459 * unlock_page() - unlock a locked page
460 *
461 * @page: the page
462 *
463 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
464 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
465 * mechananism between PageLocked pages and PageWriteback pages is shared.
466 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
467 *
468 * The first mb is necessary to safely close the critical section opened by the
469 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
470 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
471 * parallel wait_on_page_locked()).
472 */
473void fastcall unlock_page(struct page *page)
474{
475 smp_mb__before_clear_bit();
476 if (!TestClearPageLocked(page))
477 BUG();
478 smp_mb__after_clear_bit();
479 wake_up_page(page, PG_locked);
480}
481EXPORT_SYMBOL(unlock_page);
482
483/*
484 * End writeback against a page.
485 */
486void end_page_writeback(struct page *page)
487{
488 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
489 if (!test_clear_page_writeback(page))
490 BUG();
491 }
492 smp_mb__after_clear_bit();
493 wake_up_page(page, PG_writeback);
494}
495EXPORT_SYMBOL(end_page_writeback);
496
497/*
498 * Get a lock on the page, assuming we need to sleep to get it.
499 *
500 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
501 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
502 * chances are that on the second loop, the block layer's plug list is empty,
503 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
504 */
505void fastcall __lock_page(struct page *page)
506{
507 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
508
509 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
510 TASK_UNINTERRUPTIBLE);
511}
512EXPORT_SYMBOL(__lock_page);
513
514/*
515 * a rather lightweight function, finding and getting a reference to a
516 * hashed page atomically.
517 */
518struct page * find_get_page(struct address_space *mapping, unsigned long offset)
519{
520 struct page *page;
521
522 read_lock_irq(&mapping->tree_lock);
523 page = radix_tree_lookup(&mapping->page_tree, offset);
524 if (page)
525 page_cache_get(page);
526 read_unlock_irq(&mapping->tree_lock);
527 return page;
528}
529
530EXPORT_SYMBOL(find_get_page);
531
532/*
533 * Same as above, but trylock it instead of incrementing the count.
534 */
535struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
536{
537 struct page *page;
538
539 read_lock_irq(&mapping->tree_lock);
540 page = radix_tree_lookup(&mapping->page_tree, offset);
541 if (page && TestSetPageLocked(page))
542 page = NULL;
543 read_unlock_irq(&mapping->tree_lock);
544 return page;
545}
546
547EXPORT_SYMBOL(find_trylock_page);
548
549/**
550 * find_lock_page - locate, pin and lock a pagecache page
551 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700552 * @mapping: the address_space to search
553 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 *
555 * Locates the desired pagecache page, locks it, increments its reference
556 * count and returns its address.
557 *
558 * Returns zero if the page was not present. find_lock_page() may sleep.
559 */
560struct page *find_lock_page(struct address_space *mapping,
561 unsigned long offset)
562{
563 struct page *page;
564
565 read_lock_irq(&mapping->tree_lock);
566repeat:
567 page = radix_tree_lookup(&mapping->page_tree, offset);
568 if (page) {
569 page_cache_get(page);
570 if (TestSetPageLocked(page)) {
571 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800572 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573 read_lock_irq(&mapping->tree_lock);
574
575 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800576 if (unlikely(page->mapping != mapping ||
577 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 unlock_page(page);
579 page_cache_release(page);
580 goto repeat;
581 }
582 }
583 }
584 read_unlock_irq(&mapping->tree_lock);
585 return page;
586}
587
588EXPORT_SYMBOL(find_lock_page);
589
590/**
591 * find_or_create_page - locate or add a pagecache page
592 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700593 * @mapping: the page's address_space
594 * @index: the page's index into the mapping
595 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 *
597 * Locates a page in the pagecache. If the page is not present, a new page
598 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
599 * LRU list. The returned page is locked and has its reference count
600 * incremented.
601 *
602 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
603 * allocation!
604 *
605 * find_or_create_page() returns the desired page's address, or zero on
606 * memory exhaustion.
607 */
608struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400609 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610{
611 struct page *page, *cached_page = NULL;
612 int err;
613repeat:
614 page = find_lock_page(mapping, index);
615 if (!page) {
616 if (!cached_page) {
617 cached_page = alloc_page(gfp_mask);
618 if (!cached_page)
619 return NULL;
620 }
621 err = add_to_page_cache_lru(cached_page, mapping,
622 index, gfp_mask);
623 if (!err) {
624 page = cached_page;
625 cached_page = NULL;
626 } else if (err == -EEXIST)
627 goto repeat;
628 }
629 if (cached_page)
630 page_cache_release(cached_page);
631 return page;
632}
633
634EXPORT_SYMBOL(find_or_create_page);
635
636/**
637 * find_get_pages - gang pagecache lookup
638 * @mapping: The address_space to search
639 * @start: The starting page index
640 * @nr_pages: The maximum number of pages
641 * @pages: Where the resulting pages are placed
642 *
643 * find_get_pages() will search for and return a group of up to
644 * @nr_pages pages in the mapping. The pages are placed at @pages.
645 * find_get_pages() takes a reference against the returned pages.
646 *
647 * The search returns a group of mapping-contiguous pages with ascending
648 * indexes. There may be holes in the indices due to not-present pages.
649 *
650 * find_get_pages() returns the number of pages which were found.
651 */
652unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
653 unsigned int nr_pages, struct page **pages)
654{
655 unsigned int i;
656 unsigned int ret;
657
658 read_lock_irq(&mapping->tree_lock);
659 ret = radix_tree_gang_lookup(&mapping->page_tree,
660 (void **)pages, start, nr_pages);
661 for (i = 0; i < ret; i++)
662 page_cache_get(pages[i]);
663 read_unlock_irq(&mapping->tree_lock);
664 return ret;
665}
666
667/*
668 * Like find_get_pages, except we only return pages which are tagged with
669 * `tag'. We update *index to index the next page for the traversal.
670 */
671unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
672 int tag, unsigned int nr_pages, struct page **pages)
673{
674 unsigned int i;
675 unsigned int ret;
676
677 read_lock_irq(&mapping->tree_lock);
678 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
679 (void **)pages, *index, nr_pages, tag);
680 for (i = 0; i < ret; i++)
681 page_cache_get(pages[i]);
682 if (ret)
683 *index = pages[ret - 1]->index + 1;
684 read_unlock_irq(&mapping->tree_lock);
685 return ret;
686}
687
688/*
689 * Same as grab_cache_page, but do not wait if the page is unavailable.
690 * This is intended for speculative data generators, where the data can
691 * be regenerated if the page couldn't be grabbed. This routine should
692 * be safe to call while holding the lock for another page.
693 *
694 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
695 * and deadlock against the caller's locked page.
696 */
697struct page *
698grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
699{
700 struct page *page = find_get_page(mapping, index);
Al Viro6daa0e22005-10-21 03:18:50 -0400701 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702
703 if (page) {
704 if (!TestSetPageLocked(page))
705 return page;
706 page_cache_release(page);
707 return NULL;
708 }
709 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
710 page = alloc_pages(gfp_mask, 0);
711 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
712 page_cache_release(page);
713 page = NULL;
714 }
715 return page;
716}
717
718EXPORT_SYMBOL(grab_cache_page_nowait);
719
720/*
721 * This is a generic file read routine, and uses the
722 * mapping->a_ops->readpage() function for the actual low-level
723 * stuff.
724 *
725 * This is really ugly. But the goto's actually try to clarify some
726 * of the logic when it comes to error handling etc.
727 *
728 * Note the struct file* is only passed for the use of readpage. It may be
729 * NULL.
730 */
731void do_generic_mapping_read(struct address_space *mapping,
732 struct file_ra_state *_ra,
733 struct file *filp,
734 loff_t *ppos,
735 read_descriptor_t *desc,
736 read_actor_t actor)
737{
738 struct inode *inode = mapping->host;
739 unsigned long index;
740 unsigned long end_index;
741 unsigned long offset;
742 unsigned long last_index;
743 unsigned long next_index;
744 unsigned long prev_index;
745 loff_t isize;
746 struct page *cached_page;
747 int error;
748 struct file_ra_state ra = *_ra;
749
750 cached_page = NULL;
751 index = *ppos >> PAGE_CACHE_SHIFT;
752 next_index = index;
753 prev_index = ra.prev_page;
754 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
755 offset = *ppos & ~PAGE_CACHE_MASK;
756
757 isize = i_size_read(inode);
758 if (!isize)
759 goto out;
760
761 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
762 for (;;) {
763 struct page *page;
764 unsigned long nr, ret;
765
766 /* nr is the maximum number of bytes to copy from this page */
767 nr = PAGE_CACHE_SIZE;
768 if (index >= end_index) {
769 if (index > end_index)
770 goto out;
771 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
772 if (nr <= offset) {
773 goto out;
774 }
775 }
776 nr = nr - offset;
777
778 cond_resched();
779 if (index == next_index)
780 next_index = page_cache_readahead(mapping, &ra, filp,
781 index, last_index - index);
782
783find_page:
784 page = find_get_page(mapping, index);
785 if (unlikely(page == NULL)) {
786 handle_ra_miss(mapping, &ra, index);
787 goto no_cached_page;
788 }
789 if (!PageUptodate(page))
790 goto page_not_up_to_date;
791page_ok:
792
793 /* If users can be writing to this page using arbitrary
794 * virtual addresses, take care about potential aliasing
795 * before reading the page on the kernel side.
796 */
797 if (mapping_writably_mapped(mapping))
798 flush_dcache_page(page);
799
800 /*
801 * When (part of) the same page is read multiple times
802 * in succession, only mark it as accessed the first time.
803 */
804 if (prev_index != index)
805 mark_page_accessed(page);
806 prev_index = index;
807
808 /*
809 * Ok, we have the page, and it's up-to-date, so
810 * now we can copy it to user space...
811 *
812 * The actor routine returns how many bytes were actually used..
813 * NOTE! This may not be the same as how much of a user buffer
814 * we filled up (we may be padding etc), so we can only update
815 * "pos" here (the actor routine has to update the user buffer
816 * pointers and the remaining count).
817 */
818 ret = actor(desc, page, offset, nr);
819 offset += ret;
820 index += offset >> PAGE_CACHE_SHIFT;
821 offset &= ~PAGE_CACHE_MASK;
822
823 page_cache_release(page);
824 if (ret == nr && desc->count)
825 continue;
826 goto out;
827
828page_not_up_to_date:
829 /* Get exclusive access to the page ... */
830 lock_page(page);
831
832 /* Did it get unhashed before we got the lock? */
833 if (!page->mapping) {
834 unlock_page(page);
835 page_cache_release(page);
836 continue;
837 }
838
839 /* Did somebody else fill it already? */
840 if (PageUptodate(page)) {
841 unlock_page(page);
842 goto page_ok;
843 }
844
845readpage:
846 /* Start the actual read. The read will unlock the page. */
847 error = mapping->a_ops->readpage(filp, page);
848
Zach Brown994fc28c2005-12-15 14:28:17 -0800849 if (unlikely(error)) {
850 if (error == AOP_TRUNCATED_PAGE) {
851 page_cache_release(page);
852 goto find_page;
853 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800855 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856
857 if (!PageUptodate(page)) {
858 lock_page(page);
859 if (!PageUptodate(page)) {
860 if (page->mapping == NULL) {
861 /*
862 * invalidate_inode_pages got it
863 */
864 unlock_page(page);
865 page_cache_release(page);
866 goto find_page;
867 }
868 unlock_page(page);
869 error = -EIO;
870 goto readpage_error;
871 }
872 unlock_page(page);
873 }
874
875 /*
876 * i_size must be checked after we have done ->readpage.
877 *
878 * Checking i_size after the readpage allows us to calculate
879 * the correct value for "nr", which means the zero-filled
880 * part of the page is not copied back to userspace (unless
881 * another truncate extends the file - this is desired though).
882 */
883 isize = i_size_read(inode);
884 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
885 if (unlikely(!isize || index > end_index)) {
886 page_cache_release(page);
887 goto out;
888 }
889
890 /* nr is the maximum number of bytes to copy from this page */
891 nr = PAGE_CACHE_SIZE;
892 if (index == end_index) {
893 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
894 if (nr <= offset) {
895 page_cache_release(page);
896 goto out;
897 }
898 }
899 nr = nr - offset;
900 goto page_ok;
901
902readpage_error:
903 /* UHHUH! A synchronous read error occurred. Report it */
904 desc->error = error;
905 page_cache_release(page);
906 goto out;
907
908no_cached_page:
909 /*
910 * Ok, it wasn't cached, so we need to create a new
911 * page..
912 */
913 if (!cached_page) {
914 cached_page = page_cache_alloc_cold(mapping);
915 if (!cached_page) {
916 desc->error = -ENOMEM;
917 goto out;
918 }
919 }
920 error = add_to_page_cache_lru(cached_page, mapping,
921 index, GFP_KERNEL);
922 if (error) {
923 if (error == -EEXIST)
924 goto find_page;
925 desc->error = error;
926 goto out;
927 }
928 page = cached_page;
929 cached_page = NULL;
930 goto readpage;
931 }
932
933out:
934 *_ra = ra;
935
936 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
937 if (cached_page)
938 page_cache_release(cached_page);
939 if (filp)
940 file_accessed(filp);
941}
942
943EXPORT_SYMBOL(do_generic_mapping_read);
944
945int file_read_actor(read_descriptor_t *desc, struct page *page,
946 unsigned long offset, unsigned long size)
947{
948 char *kaddr;
949 unsigned long left, count = desc->count;
950
951 if (size > count)
952 size = count;
953
954 /*
955 * Faults on the destination of a read are common, so do it before
956 * taking the kmap.
957 */
958 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
959 kaddr = kmap_atomic(page, KM_USER0);
960 left = __copy_to_user_inatomic(desc->arg.buf,
961 kaddr + offset, size);
962 kunmap_atomic(kaddr, KM_USER0);
963 if (left == 0)
964 goto success;
965 }
966
967 /* Do it the slow way */
968 kaddr = kmap(page);
969 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
970 kunmap(page);
971
972 if (left) {
973 size -= left;
974 desc->error = -EFAULT;
975 }
976success:
977 desc->count = count - size;
978 desc->written += size;
979 desc->arg.buf += size;
980 return size;
981}
982
983/*
984 * This is the "read()" routine for all filesystems
985 * that can use the page cache directly.
986 */
987ssize_t
988__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
989 unsigned long nr_segs, loff_t *ppos)
990{
991 struct file *filp = iocb->ki_filp;
992 ssize_t retval;
993 unsigned long seg;
994 size_t count;
995
996 count = 0;
997 for (seg = 0; seg < nr_segs; seg++) {
998 const struct iovec *iv = &iov[seg];
999
1000 /*
1001 * If any segment has a negative length, or the cumulative
1002 * length ever wraps negative then return -EINVAL.
1003 */
1004 count += iv->iov_len;
1005 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1006 return -EINVAL;
1007 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1008 continue;
1009 if (seg == 0)
1010 return -EFAULT;
1011 nr_segs = seg;
1012 count -= iv->iov_len; /* This segment is no good */
1013 break;
1014 }
1015
1016 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1017 if (filp->f_flags & O_DIRECT) {
1018 loff_t pos = *ppos, size;
1019 struct address_space *mapping;
1020 struct inode *inode;
1021
1022 mapping = filp->f_mapping;
1023 inode = mapping->host;
1024 retval = 0;
1025 if (!count)
1026 goto out; /* skip atime */
1027 size = i_size_read(inode);
1028 if (pos < size) {
1029 retval = generic_file_direct_IO(READ, iocb,
1030 iov, pos, nr_segs);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001031 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032 retval = -EIOCBQUEUED;
1033 if (retval > 0)
1034 *ppos = pos + retval;
1035 }
1036 file_accessed(filp);
1037 goto out;
1038 }
1039
1040 retval = 0;
1041 if (count) {
1042 for (seg = 0; seg < nr_segs; seg++) {
1043 read_descriptor_t desc;
1044
1045 desc.written = 0;
1046 desc.arg.buf = iov[seg].iov_base;
1047 desc.count = iov[seg].iov_len;
1048 if (desc.count == 0)
1049 continue;
1050 desc.error = 0;
1051 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1052 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001053 if (desc.error) {
1054 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 break;
1056 }
1057 }
1058 }
1059out:
1060 return retval;
1061}
1062
1063EXPORT_SYMBOL(__generic_file_aio_read);
1064
1065ssize_t
1066generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1067{
1068 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1069
1070 BUG_ON(iocb->ki_pos != pos);
1071 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1072}
1073
1074EXPORT_SYMBOL(generic_file_aio_read);
1075
1076ssize_t
1077generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1078{
1079 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1080 struct kiocb kiocb;
1081 ssize_t ret;
1082
1083 init_sync_kiocb(&kiocb, filp);
1084 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1085 if (-EIOCBQUEUED == ret)
1086 ret = wait_on_sync_kiocb(&kiocb);
1087 return ret;
1088}
1089
1090EXPORT_SYMBOL(generic_file_read);
1091
1092int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1093{
1094 ssize_t written;
1095 unsigned long count = desc->count;
1096 struct file *file = desc->arg.data;
1097
1098 if (size > count)
1099 size = count;
1100
1101 written = file->f_op->sendpage(file, page, offset,
1102 size, &file->f_pos, size<count);
1103 if (written < 0) {
1104 desc->error = written;
1105 written = 0;
1106 }
1107 desc->count = count - written;
1108 desc->written += written;
1109 return written;
1110}
1111
1112ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1113 size_t count, read_actor_t actor, void *target)
1114{
1115 read_descriptor_t desc;
1116
1117 if (!count)
1118 return 0;
1119
1120 desc.written = 0;
1121 desc.count = count;
1122 desc.arg.data = target;
1123 desc.error = 0;
1124
1125 do_generic_file_read(in_file, ppos, &desc, actor);
1126 if (desc.written)
1127 return desc.written;
1128 return desc.error;
1129}
1130
1131EXPORT_SYMBOL(generic_file_sendfile);
1132
1133static ssize_t
1134do_readahead(struct address_space *mapping, struct file *filp,
1135 unsigned long index, unsigned long nr)
1136{
1137 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1138 return -EINVAL;
1139
1140 force_page_cache_readahead(mapping, filp, index,
1141 max_sane_readahead(nr));
1142 return 0;
1143}
1144
1145asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1146{
1147 ssize_t ret;
1148 struct file *file;
1149
1150 ret = -EBADF;
1151 file = fget(fd);
1152 if (file) {
1153 if (file->f_mode & FMODE_READ) {
1154 struct address_space *mapping = file->f_mapping;
1155 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1156 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1157 unsigned long len = end - start + 1;
1158 ret = do_readahead(mapping, file, start, len);
1159 }
1160 fput(file);
1161 }
1162 return ret;
1163}
1164
1165#ifdef CONFIG_MMU
1166/*
1167 * This adds the requested page to the page cache if it isn't already there,
1168 * and schedules an I/O to read in its contents from disk.
1169 */
1170static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1171static int fastcall page_cache_read(struct file * file, unsigned long offset)
1172{
1173 struct address_space *mapping = file->f_mapping;
1174 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001175 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176
Zach Brown994fc28c2005-12-15 14:28:17 -08001177 do {
1178 page = page_cache_alloc_cold(mapping);
1179 if (!page)
1180 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181
Zach Brown994fc28c2005-12-15 14:28:17 -08001182 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1183 if (ret == 0)
1184 ret = mapping->a_ops->readpage(file, page);
1185 else if (ret == -EEXIST)
1186 ret = 0; /* losing race to add is OK */
1187
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189
Zach Brown994fc28c2005-12-15 14:28:17 -08001190 } while (ret == AOP_TRUNCATED_PAGE);
1191
1192 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193}
1194
1195#define MMAP_LOTSAMISS (100)
1196
1197/*
1198 * filemap_nopage() is invoked via the vma operations vector for a
1199 * mapped memory region to read in file data during a page fault.
1200 *
1201 * The goto's are kind of ugly, but this streamlines the normal case of having
1202 * it in the page cache, and handles the special cases reasonably without
1203 * having a lot of duplicated code.
1204 */
1205struct page *filemap_nopage(struct vm_area_struct *area,
1206 unsigned long address, int *type)
1207{
1208 int error;
1209 struct file *file = area->vm_file;
1210 struct address_space *mapping = file->f_mapping;
1211 struct file_ra_state *ra = &file->f_ra;
1212 struct inode *inode = mapping->host;
1213 struct page *page;
1214 unsigned long size, pgoff;
1215 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1216
1217 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1218
1219retry_all:
1220 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1221 if (pgoff >= size)
1222 goto outside_data_content;
1223
1224 /* If we don't want any read-ahead, don't bother */
1225 if (VM_RandomReadHint(area))
1226 goto no_cached_page;
1227
1228 /*
1229 * The readahead code wants to be told about each and every page
1230 * so it can build and shrink its windows appropriately
1231 *
1232 * For sequential accesses, we use the generic readahead logic.
1233 */
1234 if (VM_SequentialReadHint(area))
1235 page_cache_readahead(mapping, ra, file, pgoff, 1);
1236
1237 /*
1238 * Do we have something in the page cache already?
1239 */
1240retry_find:
1241 page = find_get_page(mapping, pgoff);
1242 if (!page) {
1243 unsigned long ra_pages;
1244
1245 if (VM_SequentialReadHint(area)) {
1246 handle_ra_miss(mapping, ra, pgoff);
1247 goto no_cached_page;
1248 }
1249 ra->mmap_miss++;
1250
1251 /*
1252 * Do we miss much more than hit in this file? If so,
1253 * stop bothering with read-ahead. It will only hurt.
1254 */
1255 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1256 goto no_cached_page;
1257
1258 /*
1259 * To keep the pgmajfault counter straight, we need to
1260 * check did_readaround, as this is an inner loop.
1261 */
1262 if (!did_readaround) {
1263 majmin = VM_FAULT_MAJOR;
1264 inc_page_state(pgmajfault);
1265 }
1266 did_readaround = 1;
1267 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1268 if (ra_pages) {
1269 pgoff_t start = 0;
1270
1271 if (pgoff > ra_pages / 2)
1272 start = pgoff - ra_pages / 2;
1273 do_page_cache_readahead(mapping, file, start, ra_pages);
1274 }
1275 page = find_get_page(mapping, pgoff);
1276 if (!page)
1277 goto no_cached_page;
1278 }
1279
1280 if (!did_readaround)
1281 ra->mmap_hit++;
1282
1283 /*
1284 * Ok, found a page in the page cache, now we need to check
1285 * that it's up-to-date.
1286 */
1287 if (!PageUptodate(page))
1288 goto page_not_uptodate;
1289
1290success:
1291 /*
1292 * Found the page and have a reference on it.
1293 */
1294 mark_page_accessed(page);
1295 if (type)
1296 *type = majmin;
1297 return page;
1298
1299outside_data_content:
1300 /*
1301 * An external ptracer can access pages that normally aren't
1302 * accessible..
1303 */
1304 if (area->vm_mm == current->mm)
1305 return NULL;
1306 /* Fall through to the non-read-ahead case */
1307no_cached_page:
1308 /*
1309 * We're only likely to ever get here if MADV_RANDOM is in
1310 * effect.
1311 */
1312 error = page_cache_read(file, pgoff);
1313 grab_swap_token();
1314
1315 /*
1316 * The page we want has now been added to the page cache.
1317 * In the unlikely event that someone removed it in the
1318 * meantime, we'll just come back here and read it again.
1319 */
1320 if (error >= 0)
1321 goto retry_find;
1322
1323 /*
1324 * An error return from page_cache_read can result if the
1325 * system is low on memory, or a problem occurs while trying
1326 * to schedule I/O.
1327 */
1328 if (error == -ENOMEM)
1329 return NOPAGE_OOM;
1330 return NULL;
1331
1332page_not_uptodate:
1333 if (!did_readaround) {
1334 majmin = VM_FAULT_MAJOR;
1335 inc_page_state(pgmajfault);
1336 }
1337 lock_page(page);
1338
1339 /* Did it get unhashed while we waited for it? */
1340 if (!page->mapping) {
1341 unlock_page(page);
1342 page_cache_release(page);
1343 goto retry_all;
1344 }
1345
1346 /* Did somebody else get it up-to-date? */
1347 if (PageUptodate(page)) {
1348 unlock_page(page);
1349 goto success;
1350 }
1351
Zach Brown994fc28c2005-12-15 14:28:17 -08001352 error = mapping->a_ops->readpage(file, page);
1353 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 wait_on_page_locked(page);
1355 if (PageUptodate(page))
1356 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001357 } else if (error == AOP_TRUNCATED_PAGE) {
1358 page_cache_release(page);
1359 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 }
1361
1362 /*
1363 * Umm, take care of errors if the page isn't up-to-date.
1364 * Try to re-read it _once_. We do this synchronously,
1365 * because there really aren't any performance issues here
1366 * and we need to check for errors.
1367 */
1368 lock_page(page);
1369
1370 /* Somebody truncated the page on us? */
1371 if (!page->mapping) {
1372 unlock_page(page);
1373 page_cache_release(page);
1374 goto retry_all;
1375 }
1376
1377 /* Somebody else successfully read it in? */
1378 if (PageUptodate(page)) {
1379 unlock_page(page);
1380 goto success;
1381 }
1382 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001383 error = mapping->a_ops->readpage(file, page);
1384 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 wait_on_page_locked(page);
1386 if (PageUptodate(page))
1387 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001388 } else if (error == AOP_TRUNCATED_PAGE) {
1389 page_cache_release(page);
1390 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 }
1392
1393 /*
1394 * Things didn't work out. Return zero to tell the
1395 * mm layer so, possibly freeing the page cache page first.
1396 */
1397 page_cache_release(page);
1398 return NULL;
1399}
1400
1401EXPORT_SYMBOL(filemap_nopage);
1402
1403static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1404 int nonblock)
1405{
1406 struct address_space *mapping = file->f_mapping;
1407 struct page *page;
1408 int error;
1409
1410 /*
1411 * Do we have something in the page cache already?
1412 */
1413retry_find:
1414 page = find_get_page(mapping, pgoff);
1415 if (!page) {
1416 if (nonblock)
1417 return NULL;
1418 goto no_cached_page;
1419 }
1420
1421 /*
1422 * Ok, found a page in the page cache, now we need to check
1423 * that it's up-to-date.
1424 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001425 if (!PageUptodate(page)) {
1426 if (nonblock) {
1427 page_cache_release(page);
1428 return NULL;
1429 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001430 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001431 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432
1433success:
1434 /*
1435 * Found the page and have a reference on it.
1436 */
1437 mark_page_accessed(page);
1438 return page;
1439
1440no_cached_page:
1441 error = page_cache_read(file, pgoff);
1442
1443 /*
1444 * The page we want has now been added to the page cache.
1445 * In the unlikely event that someone removed it in the
1446 * meantime, we'll just come back here and read it again.
1447 */
1448 if (error >= 0)
1449 goto retry_find;
1450
1451 /*
1452 * An error return from page_cache_read can result if the
1453 * system is low on memory, or a problem occurs while trying
1454 * to schedule I/O.
1455 */
1456 return NULL;
1457
1458page_not_uptodate:
1459 lock_page(page);
1460
1461 /* Did it get unhashed while we waited for it? */
1462 if (!page->mapping) {
1463 unlock_page(page);
1464 goto err;
1465 }
1466
1467 /* Did somebody else get it up-to-date? */
1468 if (PageUptodate(page)) {
1469 unlock_page(page);
1470 goto success;
1471 }
1472
Zach Brown994fc28c2005-12-15 14:28:17 -08001473 error = mapping->a_ops->readpage(file, page);
1474 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 wait_on_page_locked(page);
1476 if (PageUptodate(page))
1477 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001478 } else if (error == AOP_TRUNCATED_PAGE) {
1479 page_cache_release(page);
1480 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 }
1482
1483 /*
1484 * Umm, take care of errors if the page isn't up-to-date.
1485 * Try to re-read it _once_. We do this synchronously,
1486 * because there really aren't any performance issues here
1487 * and we need to check for errors.
1488 */
1489 lock_page(page);
1490
1491 /* Somebody truncated the page on us? */
1492 if (!page->mapping) {
1493 unlock_page(page);
1494 goto err;
1495 }
1496 /* Somebody else successfully read it in? */
1497 if (PageUptodate(page)) {
1498 unlock_page(page);
1499 goto success;
1500 }
1501
1502 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001503 error = mapping->a_ops->readpage(file, page);
1504 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 wait_on_page_locked(page);
1506 if (PageUptodate(page))
1507 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001508 } else if (error == AOP_TRUNCATED_PAGE) {
1509 page_cache_release(page);
1510 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 }
1512
1513 /*
1514 * Things didn't work out. Return zero to tell the
1515 * mm layer so, possibly freeing the page cache page first.
1516 */
1517err:
1518 page_cache_release(page);
1519
1520 return NULL;
1521}
1522
1523int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1524 unsigned long len, pgprot_t prot, unsigned long pgoff,
1525 int nonblock)
1526{
1527 struct file *file = vma->vm_file;
1528 struct address_space *mapping = file->f_mapping;
1529 struct inode *inode = mapping->host;
1530 unsigned long size;
1531 struct mm_struct *mm = vma->vm_mm;
1532 struct page *page;
1533 int err;
1534
1535 if (!nonblock)
1536 force_page_cache_readahead(mapping, vma->vm_file,
1537 pgoff, len >> PAGE_CACHE_SHIFT);
1538
1539repeat:
1540 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1541 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1542 return -EINVAL;
1543
1544 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001545
1546 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1547 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 if (!page && !nonblock)
1549 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001550
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 if (page) {
1552 err = install_page(mm, vma, addr, page, prot);
1553 if (err) {
1554 page_cache_release(page);
1555 return err;
1556 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001557 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001558 /* No page was found just because we can't read it in now (being
1559 * here implies nonblock != 0), but the page may exist, so set
1560 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 err = install_file_pte(mm, vma, addr, pgoff, prot);
1562 if (err)
1563 return err;
1564 }
1565
1566 len -= PAGE_SIZE;
1567 addr += PAGE_SIZE;
1568 pgoff++;
1569 if (len)
1570 goto repeat;
1571
1572 return 0;
1573}
Nikita Danilovb1459462005-10-29 18:17:02 -07001574EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575
1576struct vm_operations_struct generic_file_vm_ops = {
1577 .nopage = filemap_nopage,
1578 .populate = filemap_populate,
1579};
1580
1581/* This is used for a general mmap of a disk file */
1582
1583int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1584{
1585 struct address_space *mapping = file->f_mapping;
1586
1587 if (!mapping->a_ops->readpage)
1588 return -ENOEXEC;
1589 file_accessed(file);
1590 vma->vm_ops = &generic_file_vm_ops;
1591 return 0;
1592}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593
1594/*
1595 * This is for filesystems which do not implement ->writepage.
1596 */
1597int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1598{
1599 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1600 return -EINVAL;
1601 return generic_file_mmap(file, vma);
1602}
1603#else
1604int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1605{
1606 return -ENOSYS;
1607}
1608int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1609{
1610 return -ENOSYS;
1611}
1612#endif /* CONFIG_MMU */
1613
1614EXPORT_SYMBOL(generic_file_mmap);
1615EXPORT_SYMBOL(generic_file_readonly_mmap);
1616
1617static inline struct page *__read_cache_page(struct address_space *mapping,
1618 unsigned long index,
1619 int (*filler)(void *,struct page*),
1620 void *data)
1621{
1622 struct page *page, *cached_page = NULL;
1623 int err;
1624repeat:
1625 page = find_get_page(mapping, index);
1626 if (!page) {
1627 if (!cached_page) {
1628 cached_page = page_cache_alloc_cold(mapping);
1629 if (!cached_page)
1630 return ERR_PTR(-ENOMEM);
1631 }
1632 err = add_to_page_cache_lru(cached_page, mapping,
1633 index, GFP_KERNEL);
1634 if (err == -EEXIST)
1635 goto repeat;
1636 if (err < 0) {
1637 /* Presumably ENOMEM for radix tree node */
1638 page_cache_release(cached_page);
1639 return ERR_PTR(err);
1640 }
1641 page = cached_page;
1642 cached_page = NULL;
1643 err = filler(data, page);
1644 if (err < 0) {
1645 page_cache_release(page);
1646 page = ERR_PTR(err);
1647 }
1648 }
1649 if (cached_page)
1650 page_cache_release(cached_page);
1651 return page;
1652}
1653
1654/*
1655 * Read into the page cache. If a page already exists,
1656 * and PageUptodate() is not set, try to fill the page.
1657 */
1658struct page *read_cache_page(struct address_space *mapping,
1659 unsigned long index,
1660 int (*filler)(void *,struct page*),
1661 void *data)
1662{
1663 struct page *page;
1664 int err;
1665
1666retry:
1667 page = __read_cache_page(mapping, index, filler, data);
1668 if (IS_ERR(page))
1669 goto out;
1670 mark_page_accessed(page);
1671 if (PageUptodate(page))
1672 goto out;
1673
1674 lock_page(page);
1675 if (!page->mapping) {
1676 unlock_page(page);
1677 page_cache_release(page);
1678 goto retry;
1679 }
1680 if (PageUptodate(page)) {
1681 unlock_page(page);
1682 goto out;
1683 }
1684 err = filler(data, page);
1685 if (err < 0) {
1686 page_cache_release(page);
1687 page = ERR_PTR(err);
1688 }
1689 out:
1690 return page;
1691}
1692
1693EXPORT_SYMBOL(read_cache_page);
1694
1695/*
1696 * If the page was newly created, increment its refcount and add it to the
1697 * caller's lru-buffering pagevec. This function is specifically for
1698 * generic_file_write().
1699 */
1700static inline struct page *
1701__grab_cache_page(struct address_space *mapping, unsigned long index,
1702 struct page **cached_page, struct pagevec *lru_pvec)
1703{
1704 int err;
1705 struct page *page;
1706repeat:
1707 page = find_lock_page(mapping, index);
1708 if (!page) {
1709 if (!*cached_page) {
1710 *cached_page = page_cache_alloc(mapping);
1711 if (!*cached_page)
1712 return NULL;
1713 }
1714 err = add_to_page_cache(*cached_page, mapping,
1715 index, GFP_KERNEL);
1716 if (err == -EEXIST)
1717 goto repeat;
1718 if (err == 0) {
1719 page = *cached_page;
1720 page_cache_get(page);
1721 if (!pagevec_add(lru_pvec, page))
1722 __pagevec_lru_add(lru_pvec);
1723 *cached_page = NULL;
1724 }
1725 }
1726 return page;
1727}
1728
1729/*
1730 * The logic we want is
1731 *
1732 * if suid or (sgid and xgrp)
1733 * remove privs
1734 */
1735int remove_suid(struct dentry *dentry)
1736{
1737 mode_t mode = dentry->d_inode->i_mode;
1738 int kill = 0;
1739 int result = 0;
1740
1741 /* suid always must be killed */
1742 if (unlikely(mode & S_ISUID))
1743 kill = ATTR_KILL_SUID;
1744
1745 /*
1746 * sgid without any exec bits is just a mandatory locking mark; leave
1747 * it alone. If some exec bits are set, it's a real sgid; kill it.
1748 */
1749 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1750 kill |= ATTR_KILL_SGID;
1751
1752 if (unlikely(kill && !capable(CAP_FSETID))) {
1753 struct iattr newattrs;
1754
1755 newattrs.ia_valid = ATTR_FORCE | kill;
1756 result = notify_change(dentry, &newattrs);
1757 }
1758 return result;
1759}
1760EXPORT_SYMBOL(remove_suid);
1761
Carsten Otteceffc072005-06-23 22:05:25 -07001762size_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763__filemap_copy_from_user_iovec(char *vaddr,
1764 const struct iovec *iov, size_t base, size_t bytes)
1765{
1766 size_t copied = 0, left = 0;
1767
1768 while (bytes) {
1769 char __user *buf = iov->iov_base + base;
1770 int copy = min(bytes, iov->iov_len - base);
1771
1772 base = 0;
1773 left = __copy_from_user_inatomic(vaddr, buf, copy);
1774 copied += copy;
1775 bytes -= copy;
1776 vaddr += copy;
1777 iov++;
1778
1779 if (unlikely(left)) {
1780 /* zero the rest of the target like __copy_from_user */
1781 if (bytes)
1782 memset(vaddr, 0, bytes);
1783 break;
1784 }
1785 }
1786 return copied - left;
1787}
1788
1789/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 * Performs necessary checks before doing a write
1791 *
1792 * Can adjust writing position aor amount of bytes to write.
1793 * Returns appropriate error code that caller should return or
1794 * zero in case that write should be allowed.
1795 */
1796inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1797{
1798 struct inode *inode = file->f_mapping->host;
1799 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1800
1801 if (unlikely(*pos < 0))
1802 return -EINVAL;
1803
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 if (!isblk) {
1805 /* FIXME: this is for backwards compatibility with 2.4 */
1806 if (file->f_flags & O_APPEND)
1807 *pos = i_size_read(inode);
1808
1809 if (limit != RLIM_INFINITY) {
1810 if (*pos >= limit) {
1811 send_sig(SIGXFSZ, current, 0);
1812 return -EFBIG;
1813 }
1814 if (*count > limit - (typeof(limit))*pos) {
1815 *count = limit - (typeof(limit))*pos;
1816 }
1817 }
1818 }
1819
1820 /*
1821 * LFS rule
1822 */
1823 if (unlikely(*pos + *count > MAX_NON_LFS &&
1824 !(file->f_flags & O_LARGEFILE))) {
1825 if (*pos >= MAX_NON_LFS) {
1826 send_sig(SIGXFSZ, current, 0);
1827 return -EFBIG;
1828 }
1829 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1830 *count = MAX_NON_LFS - (unsigned long)*pos;
1831 }
1832 }
1833
1834 /*
1835 * Are we about to exceed the fs block limit ?
1836 *
1837 * If we have written data it becomes a short write. If we have
1838 * exceeded without writing data we send a signal and return EFBIG.
1839 * Linus frestrict idea will clean these up nicely..
1840 */
1841 if (likely(!isblk)) {
1842 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1843 if (*count || *pos > inode->i_sb->s_maxbytes) {
1844 send_sig(SIGXFSZ, current, 0);
1845 return -EFBIG;
1846 }
1847 /* zero-length writes at ->s_maxbytes are OK */
1848 }
1849
1850 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1851 *count = inode->i_sb->s_maxbytes - *pos;
1852 } else {
1853 loff_t isize;
1854 if (bdev_read_only(I_BDEV(inode)))
1855 return -EPERM;
1856 isize = i_size_read(inode);
1857 if (*pos >= isize) {
1858 if (*count || *pos > isize)
1859 return -ENOSPC;
1860 }
1861
1862 if (*pos + *count > isize)
1863 *count = isize - *pos;
1864 }
1865 return 0;
1866}
1867EXPORT_SYMBOL(generic_write_checks);
1868
1869ssize_t
1870generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1871 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1872 size_t count, size_t ocount)
1873{
1874 struct file *file = iocb->ki_filp;
1875 struct address_space *mapping = file->f_mapping;
1876 struct inode *inode = mapping->host;
1877 ssize_t written;
1878
1879 if (count != ocount)
1880 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1881
1882 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1883 if (written > 0) {
1884 loff_t end = pos + written;
1885 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1886 i_size_write(inode, end);
1887 mark_inode_dirty(inode);
1888 }
1889 *ppos = end;
1890 }
1891
1892 /*
1893 * Sync the fs metadata but not the minor inode changes and
1894 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001895 * i_mutex is held, which protects generic_osync_inode() from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896 * livelocking.
1897 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07001898 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1899 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1900 if (err < 0)
1901 written = err;
1902 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903 if (written == count && !is_sync_kiocb(iocb))
1904 written = -EIOCBQUEUED;
1905 return written;
1906}
1907EXPORT_SYMBOL(generic_file_direct_write);
1908
1909ssize_t
1910generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1911 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1912 size_t count, ssize_t written)
1913{
1914 struct file *file = iocb->ki_filp;
1915 struct address_space * mapping = file->f_mapping;
1916 struct address_space_operations *a_ops = mapping->a_ops;
1917 struct inode *inode = mapping->host;
1918 long status = 0;
1919 struct page *page;
1920 struct page *cached_page = NULL;
1921 size_t bytes;
1922 struct pagevec lru_pvec;
1923 const struct iovec *cur_iov = iov; /* current iovec */
1924 size_t iov_base = 0; /* offset in the current iovec */
1925 char __user *buf;
1926
1927 pagevec_init(&lru_pvec, 0);
1928
1929 /*
1930 * handle partial DIO write. Adjust cur_iov if needed.
1931 */
1932 if (likely(nr_segs == 1))
1933 buf = iov->iov_base + written;
1934 else {
1935 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07001936 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937 }
1938
1939 do {
1940 unsigned long index;
1941 unsigned long offset;
Martin Schwidefskya5117182005-06-06 13:35:54 -07001942 unsigned long maxlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 size_t copied;
1944
1945 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1946 index = pos >> PAGE_CACHE_SHIFT;
1947 bytes = PAGE_CACHE_SIZE - offset;
1948 if (bytes > count)
1949 bytes = count;
1950
1951 /*
1952 * Bring in the user page that we will copy from _first_.
1953 * Otherwise there's a nasty deadlock on copying from the
1954 * same page as we're writing to, without it being marked
1955 * up-to-date.
1956 */
Martin Schwidefskya5117182005-06-06 13:35:54 -07001957 maxlen = cur_iov->iov_len - iov_base;
1958 if (maxlen > bytes)
1959 maxlen = bytes;
1960 fault_in_pages_readable(buf, maxlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001961
1962 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
1963 if (!page) {
1964 status = -ENOMEM;
1965 break;
1966 }
1967
1968 status = a_ops->prepare_write(file, page, offset, offset+bytes);
1969 if (unlikely(status)) {
1970 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08001971
1972 if (status != AOP_TRUNCATED_PAGE)
1973 unlock_page(page);
1974 page_cache_release(page);
1975 if (status == AOP_TRUNCATED_PAGE)
1976 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977 /*
1978 * prepare_write() may have instantiated a few blocks
1979 * outside i_size. Trim these off again.
1980 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 if (pos + bytes > isize)
1982 vmtruncate(inode, isize);
1983 break;
1984 }
1985 if (likely(nr_segs == 1))
1986 copied = filemap_copy_from_user(page, offset,
1987 buf, bytes);
1988 else
1989 copied = filemap_copy_from_user_iovec(page, offset,
1990 cur_iov, iov_base, bytes);
1991 flush_dcache_page(page);
1992 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08001993 if (status == AOP_TRUNCATED_PAGE) {
1994 page_cache_release(page);
1995 continue;
1996 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997 if (likely(copied > 0)) {
1998 if (!status)
1999 status = copied;
2000
2001 if (status >= 0) {
2002 written += status;
2003 count -= status;
2004 pos += status;
2005 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002006 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 filemap_set_next_iovec(&cur_iov,
2008 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002009 if (count)
2010 buf = cur_iov->iov_base +
2011 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002012 } else {
2013 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002014 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015 }
2016 }
2017 if (unlikely(copied != bytes))
2018 if (status >= 0)
2019 status = -EFAULT;
2020 unlock_page(page);
2021 mark_page_accessed(page);
2022 page_cache_release(page);
2023 if (status < 0)
2024 break;
2025 balance_dirty_pages_ratelimited(mapping);
2026 cond_resched();
2027 } while (count);
2028 *ppos = pos;
2029
2030 if (cached_page)
2031 page_cache_release(cached_page);
2032
2033 /*
2034 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2035 */
2036 if (likely(status >= 0)) {
2037 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2038 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2039 status = generic_osync_inode(inode, mapping,
2040 OSYNC_METADATA|OSYNC_DATA);
2041 }
2042 }
2043
2044 /*
2045 * If we get here for O_DIRECT writes then we must have fallen through
2046 * to buffered writes (block instantiation inside i_size). So we sync
2047 * the file data here, to try to honour O_DIRECT expectations.
2048 */
2049 if (unlikely(file->f_flags & O_DIRECT) && written)
2050 status = filemap_write_and_wait(mapping);
2051
2052 pagevec_lru_add(&lru_pvec);
2053 return written ? written : status;
2054}
2055EXPORT_SYMBOL(generic_file_buffered_write);
2056
Adrian Bunk5ce78522005-09-10 00:26:28 -07002057static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2059 unsigned long nr_segs, loff_t *ppos)
2060{
2061 struct file *file = iocb->ki_filp;
2062 struct address_space * mapping = file->f_mapping;
2063 size_t ocount; /* original count */
2064 size_t count; /* after file limit checks */
2065 struct inode *inode = mapping->host;
2066 unsigned long seg;
2067 loff_t pos;
2068 ssize_t written;
2069 ssize_t err;
2070
2071 ocount = 0;
2072 for (seg = 0; seg < nr_segs; seg++) {
2073 const struct iovec *iv = &iov[seg];
2074
2075 /*
2076 * If any segment has a negative length, or the cumulative
2077 * length ever wraps negative then return -EINVAL.
2078 */
2079 ocount += iv->iov_len;
2080 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2081 return -EINVAL;
2082 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2083 continue;
2084 if (seg == 0)
2085 return -EFAULT;
2086 nr_segs = seg;
2087 ocount -= iv->iov_len; /* This segment is no good */
2088 break;
2089 }
2090
2091 count = ocount;
2092 pos = *ppos;
2093
2094 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2095
2096 /* We can write back this queue in page reclaim */
2097 current->backing_dev_info = mapping->backing_dev_info;
2098 written = 0;
2099
2100 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2101 if (err)
2102 goto out;
2103
2104 if (count == 0)
2105 goto out;
2106
2107 err = remove_suid(file->f_dentry);
2108 if (err)
2109 goto out;
2110
Christoph Hellwig870f4812006-01-09 20:52:01 -08002111 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002112
2113 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2114 if (unlikely(file->f_flags & O_DIRECT)) {
2115 written = generic_file_direct_write(iocb, iov,
2116 &nr_segs, pos, ppos, count, ocount);
2117 if (written < 0 || written == count)
2118 goto out;
2119 /*
2120 * direct-io write to a hole: fall through to buffered I/O
2121 * for completing the rest of the request.
2122 */
2123 pos += written;
2124 count -= written;
2125 }
2126
2127 written = generic_file_buffered_write(iocb, iov, nr_segs,
2128 pos, ppos, count, written);
2129out:
2130 current->backing_dev_info = NULL;
2131 return written ? written : err;
2132}
2133EXPORT_SYMBOL(generic_file_aio_write_nolock);
2134
2135ssize_t
2136generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2137 unsigned long nr_segs, loff_t *ppos)
2138{
2139 struct file *file = iocb->ki_filp;
2140 struct address_space *mapping = file->f_mapping;
2141 struct inode *inode = mapping->host;
2142 ssize_t ret;
2143 loff_t pos = *ppos;
2144
2145 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2146
2147 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2148 int err;
2149
2150 err = sync_page_range_nolock(inode, mapping, pos, ret);
2151 if (err < 0)
2152 ret = err;
2153 }
2154 return ret;
2155}
2156
Adrian Bunk5ce78522005-09-10 00:26:28 -07002157static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2159 unsigned long nr_segs, loff_t *ppos)
2160{
2161 struct kiocb kiocb;
2162 ssize_t ret;
2163
2164 init_sync_kiocb(&kiocb, file);
2165 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2166 if (ret == -EIOCBQUEUED)
2167 ret = wait_on_sync_kiocb(&kiocb);
2168 return ret;
2169}
2170
2171ssize_t
2172generic_file_write_nolock(struct file *file, const struct iovec *iov,
2173 unsigned long nr_segs, loff_t *ppos)
2174{
2175 struct kiocb kiocb;
2176 ssize_t ret;
2177
2178 init_sync_kiocb(&kiocb, file);
2179 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2180 if (-EIOCBQUEUED == ret)
2181 ret = wait_on_sync_kiocb(&kiocb);
2182 return ret;
2183}
2184EXPORT_SYMBOL(generic_file_write_nolock);
2185
2186ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2187 size_t count, loff_t pos)
2188{
2189 struct file *file = iocb->ki_filp;
2190 struct address_space *mapping = file->f_mapping;
2191 struct inode *inode = mapping->host;
2192 ssize_t ret;
2193 struct iovec local_iov = { .iov_base = (void __user *)buf,
2194 .iov_len = count };
2195
2196 BUG_ON(iocb->ki_pos != pos);
2197
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002198 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2200 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002201 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002202
2203 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2204 ssize_t err;
2205
2206 err = sync_page_range(inode, mapping, pos, ret);
2207 if (err < 0)
2208 ret = err;
2209 }
2210 return ret;
2211}
2212EXPORT_SYMBOL(generic_file_aio_write);
2213
2214ssize_t generic_file_write(struct file *file, const char __user *buf,
2215 size_t count, loff_t *ppos)
2216{
2217 struct address_space *mapping = file->f_mapping;
2218 struct inode *inode = mapping->host;
2219 ssize_t ret;
2220 struct iovec local_iov = { .iov_base = (void __user *)buf,
2221 .iov_len = count };
2222
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002223 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002225 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002226
2227 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2228 ssize_t err;
2229
2230 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2231 if (err < 0)
2232 ret = err;
2233 }
2234 return ret;
2235}
2236EXPORT_SYMBOL(generic_file_write);
2237
2238ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2239 unsigned long nr_segs, loff_t *ppos)
2240{
2241 struct kiocb kiocb;
2242 ssize_t ret;
2243
2244 init_sync_kiocb(&kiocb, filp);
2245 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2246 if (-EIOCBQUEUED == ret)
2247 ret = wait_on_sync_kiocb(&kiocb);
2248 return ret;
2249}
2250EXPORT_SYMBOL(generic_file_readv);
2251
2252ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2253 unsigned long nr_segs, loff_t *ppos)
2254{
2255 struct address_space *mapping = file->f_mapping;
2256 struct inode *inode = mapping->host;
2257 ssize_t ret;
2258
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002259 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002261 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262
2263 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2264 int err;
2265
2266 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2267 if (err < 0)
2268 ret = err;
2269 }
2270 return ret;
2271}
2272EXPORT_SYMBOL(generic_file_writev);
2273
2274/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002275 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276 * went wrong during pagecache shootdown.
2277 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002278static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002279generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2280 loff_t offset, unsigned long nr_segs)
2281{
2282 struct file *file = iocb->ki_filp;
2283 struct address_space *mapping = file->f_mapping;
2284 ssize_t retval;
2285 size_t write_len = 0;
2286
2287 /*
2288 * If it's a write, unmap all mmappings of the file up-front. This
2289 * will cause any pte dirty bits to be propagated into the pageframes
2290 * for the subsequent filemap_write_and_wait().
2291 */
2292 if (rw == WRITE) {
2293 write_len = iov_length(iov, nr_segs);
2294 if (mapping_mapped(mapping))
2295 unmap_mapping_range(mapping, offset, write_len, 0);
2296 }
2297
2298 retval = filemap_write_and_wait(mapping);
2299 if (retval == 0) {
2300 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2301 offset, nr_segs);
2302 if (rw == WRITE && mapping->nrpages) {
2303 pgoff_t end = (offset + write_len - 1)
2304 >> PAGE_CACHE_SHIFT;
2305 int err = invalidate_inode_pages2_range(mapping,
2306 offset >> PAGE_CACHE_SHIFT, end);
2307 if (err)
2308 retval = err;
2309 }
2310 }
2311 return retval;
2312}