blob: a02a0b2c986bc4c415bf1b8c9d78694036993c81 [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>
Paul Jackson44110fe2006-03-24 03:16:04 -080032#include <linux/cpuset.h>
Carsten Otteceffc072005-06-23 22:05:25 -070033#include "filemap.h"
Nick Piggin0f8053a2006-03-22 00:08:33 -080034#include "internal.h"
35
Linus Torvalds1da177e2005-04-16 15:20:36 -070036/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 * FIXME: remove all knowledge of the buffer layer from the core VM
38 */
39#include <linux/buffer_head.h> /* for generic_osync_inode */
40
41#include <asm/uaccess.h>
42#include <asm/mman.h>
43
Adrian Bunk5ce78522005-09-10 00:26:28 -070044static ssize_t
45generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
46 loff_t offset, unsigned long nr_segs);
47
Linus Torvalds1da177e2005-04-16 15:20:36 -070048/*
49 * Shared mappings implemented 30.11.1994. It's not fully working yet,
50 * though.
51 *
52 * Shared mappings now work. 15.8.1995 Bruno.
53 *
54 * finished 'unifying' the page and buffer cache and SMP-threaded the
55 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
56 *
57 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
58 */
59
60/*
61 * Lock ordering:
62 *
63 * ->i_mmap_lock (vmtruncate)
64 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070065 * ->swap_lock (exclusive_swap_page, others)
66 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080068 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 * ->i_mmap_lock (truncate->unmap_mapping_range)
70 *
71 * ->mmap_sem
72 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070073 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
75 *
76 * ->mmap_sem
77 * ->lock_page (access_process_vm)
78 *
79 * ->mmap_sem
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080080 * ->i_mutex (msync)
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080082 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 * ->i_alloc_sem (various)
84 *
85 * ->inode_lock
86 * ->sb_lock (fs/fs-writeback.c)
87 * ->mapping->tree_lock (__sync_single_inode)
88 *
89 * ->i_mmap_lock
90 * ->anon_vma.lock (vma_adjust)
91 *
92 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070093 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070095 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070096 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070097 * ->private_lock (try_to_unmap_one)
98 * ->tree_lock (try_to_unmap_one)
99 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -0800100 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 * ->private_lock (page_remove_rmap->set_page_dirty)
102 * ->tree_lock (page_remove_rmap->set_page_dirty)
103 * ->inode_lock (page_remove_rmap->set_page_dirty)
104 * ->inode_lock (zap_pte_range->set_page_dirty)
105 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
106 *
107 * ->task->proc_lock
108 * ->dcache_lock (proc_pid_lookup)
109 */
110
111/*
112 * Remove a page from the page cache and free it. Caller has to make
113 * sure the page is locked and that nobody else uses it - or that usage
114 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
115 */
116void __remove_from_page_cache(struct page *page)
117{
118 struct address_space *mapping = page->mapping;
119
120 radix_tree_delete(&mapping->page_tree, page->index);
121 page->mapping = NULL;
122 mapping->nrpages--;
123 pagecache_acct(-1);
124}
125
126void remove_from_page_cache(struct page *page)
127{
128 struct address_space *mapping = page->mapping;
129
Matt Mackallcd7619d2005-05-01 08:59:01 -0700130 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131
132 write_lock_irq(&mapping->tree_lock);
133 __remove_from_page_cache(page);
134 write_unlock_irq(&mapping->tree_lock);
135}
136
137static int sync_page(void *word)
138{
139 struct address_space *mapping;
140 struct page *page;
141
Andi Kleen07808b72005-11-05 17:25:53 +0100142 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
144 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700145 * page_mapping() is being called without PG_locked held.
146 * Some knowledge of the state and use of the page is used to
147 * reduce the requirements down to a memory barrier.
148 * The danger here is of a stale page_mapping() return value
149 * indicating a struct address_space different from the one it's
150 * associated with when it is associated with one.
151 * After smp_mb(), it's either the correct page_mapping() for
152 * the page, or an old page_mapping() and the page's own
153 * page_mapping() has gone NULL.
154 * The ->sync_page() address_space operation must tolerate
155 * page_mapping() going NULL. By an amazing coincidence,
156 * this comes about because none of the users of the page
157 * in the ->sync_page() methods make essential use of the
158 * page_mapping(), merely passing the page down to the backing
159 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700160 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700161 * of interest. When page_mapping() does go NULL, the entire
162 * call stack gracefully ignores the page and returns.
163 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 */
165 smp_mb();
166 mapping = page_mapping(page);
167 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
168 mapping->a_ops->sync_page(page);
169 io_schedule();
170 return 0;
171}
172
173/**
174 * filemap_fdatawrite_range - start writeback against all of a mapping's
175 * dirty pages that lie within the byte offsets <start, end>
Martin Waitz67be2dd2005-05-01 08:59:26 -0700176 * @mapping: address space structure to write
177 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800178 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700179 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 *
181 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
182 * opposed to a regular memory * cleansing writeback. The difference between
183 * these two operations is that if a dirty page/buffer is encountered, it must
184 * be waited upon, and not just skipped over.
185 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800186int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
187 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188{
189 int ret;
190 struct writeback_control wbc = {
191 .sync_mode = sync_mode,
192 .nr_to_write = mapping->nrpages * 2,
193 .start = start,
194 .end = end,
195 };
196
197 if (!mapping_cap_writeback_dirty(mapping))
198 return 0;
199
200 ret = do_writepages(mapping, &wbc);
201 return ret;
202}
203
204static inline int __filemap_fdatawrite(struct address_space *mapping,
205 int sync_mode)
206{
207 return __filemap_fdatawrite_range(mapping, 0, 0, sync_mode);
208}
209
210int filemap_fdatawrite(struct address_space *mapping)
211{
212 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
213}
214EXPORT_SYMBOL(filemap_fdatawrite);
215
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800216static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
217 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218{
219 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
220}
221
222/*
223 * This is a mostly non-blocking flush. Not suitable for data-integrity
224 * purposes - I/O may not be started against all dirty pages.
225 */
226int filemap_flush(struct address_space *mapping)
227{
228 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
229}
230EXPORT_SYMBOL(filemap_flush);
231
232/*
233 * Wait for writeback to complete against pages indexed by start->end
234 * inclusive
235 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800236int wait_on_page_writeback_range(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 pgoff_t start, pgoff_t end)
238{
239 struct pagevec pvec;
240 int nr_pages;
241 int ret = 0;
242 pgoff_t index;
243
244 if (end < start)
245 return 0;
246
247 pagevec_init(&pvec, 0);
248 index = start;
249 while ((index <= end) &&
250 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
251 PAGECACHE_TAG_WRITEBACK,
252 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
253 unsigned i;
254
255 for (i = 0; i < nr_pages; i++) {
256 struct page *page = pvec.pages[i];
257
258 /* until radix tree lookup accepts end_index */
259 if (page->index > end)
260 continue;
261
262 wait_on_page_writeback(page);
263 if (PageError(page))
264 ret = -EIO;
265 }
266 pagevec_release(&pvec);
267 cond_resched();
268 }
269
270 /* Check for outstanding write errors */
271 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
272 ret = -ENOSPC;
273 if (test_and_clear_bit(AS_EIO, &mapping->flags))
274 ret = -EIO;
275
276 return ret;
277}
278
279/*
280 * Write and wait upon all the pages in the passed range. This is a "data
281 * integrity" operation. It waits upon in-flight writeout before starting and
282 * waiting upon new writeout. If there was an IO error, return it.
283 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800284 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 * it is otherwise livelockable.
286 */
287int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800288 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289{
290 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
291 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
292 int ret;
293
294 if (!mapping_cap_writeback_dirty(mapping) || !count)
295 return 0;
296 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
297 if (ret == 0) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800298 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800300 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 }
302 if (ret == 0)
303 ret = wait_on_page_writeback_range(mapping, start, end);
304 return ret;
305}
306EXPORT_SYMBOL(sync_page_range);
307
308/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800309 * Note: Holding i_mutex across sync_page_range_nolock is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 * as it forces O_SYNC writers to different parts of the same file
311 * to be serialised right until io completion.
312 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800313int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
314 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315{
316 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
317 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
318 int ret;
319
320 if (!mapping_cap_writeback_dirty(mapping) || !count)
321 return 0;
322 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
323 if (ret == 0)
324 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
325 if (ret == 0)
326 ret = wait_on_page_writeback_range(mapping, start, end);
327 return ret;
328}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800329EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330
331/**
332 * filemap_fdatawait - walk the list of under-writeback pages of the given
333 * address space and wait for all of them.
334 *
335 * @mapping: address space structure to wait for
336 */
337int filemap_fdatawait(struct address_space *mapping)
338{
339 loff_t i_size = i_size_read(mapping->host);
340
341 if (i_size == 0)
342 return 0;
343
344 return wait_on_page_writeback_range(mapping, 0,
345 (i_size - 1) >> PAGE_CACHE_SHIFT);
346}
347EXPORT_SYMBOL(filemap_fdatawait);
348
349int filemap_write_and_wait(struct address_space *mapping)
350{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800351 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352
353 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800354 err = filemap_fdatawrite(mapping);
355 /*
356 * Even if the above returned error, the pages may be
357 * written partially (e.g. -ENOSPC), so we wait for it.
358 * But the -EIO is special case, it may indicate the worst
359 * thing (e.g. bug) happened, so we avoid waiting for it.
360 */
361 if (err != -EIO) {
362 int err2 = filemap_fdatawait(mapping);
363 if (!err)
364 err = err2;
365 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800367 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800369EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
Andrew Morton469eb4d2006-03-24 03:17:45 -0800371/*
372 * Write out and wait upon file offsets lstart->lend, inclusive.
373 *
374 * Note that `lend' is inclusive (describes the last byte to be written) so
375 * that this function can be used to write to the very end-of-file (end = -1).
376 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377int filemap_write_and_wait_range(struct address_space *mapping,
378 loff_t lstart, loff_t lend)
379{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800380 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381
382 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800383 err = __filemap_fdatawrite_range(mapping, lstart, lend,
384 WB_SYNC_ALL);
385 /* See comment of filemap_write_and_wait() */
386 if (err != -EIO) {
387 int err2 = wait_on_page_writeback_range(mapping,
388 lstart >> PAGE_CACHE_SHIFT,
389 lend >> PAGE_CACHE_SHIFT);
390 if (!err)
391 err = err2;
392 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800394 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395}
396
397/*
398 * This function is used to add newly allocated pagecache pages:
399 * the page is new, so we can just run SetPageLocked() against it.
400 * The other page state flags were set by rmqueue().
401 *
402 * This function does not add the page to the LRU. The caller must do that.
403 */
404int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400405 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406{
407 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
408
409 if (error == 0) {
410 write_lock_irq(&mapping->tree_lock);
411 error = radix_tree_insert(&mapping->page_tree, offset, page);
412 if (!error) {
413 page_cache_get(page);
414 SetPageLocked(page);
415 page->mapping = mapping;
416 page->index = offset;
417 mapping->nrpages++;
418 pagecache_acct(1);
419 }
420 write_unlock_irq(&mapping->tree_lock);
421 radix_tree_preload_end();
422 }
423 return error;
424}
425
426EXPORT_SYMBOL(add_to_page_cache);
427
428int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400429 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430{
431 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
432 if (ret == 0)
433 lru_cache_add(page);
434 return ret;
435}
436
Paul Jackson44110fe2006-03-24 03:16:04 -0800437#ifdef CONFIG_NUMA
438struct page *page_cache_alloc(struct address_space *x)
439{
440 if (cpuset_do_page_mem_spread()) {
441 int n = cpuset_mem_spread_node();
442 return alloc_pages_node(n, mapping_gfp_mask(x), 0);
443 }
444 return alloc_pages(mapping_gfp_mask(x), 0);
445}
446EXPORT_SYMBOL(page_cache_alloc);
447
448struct page *page_cache_alloc_cold(struct address_space *x)
449{
450 if (cpuset_do_page_mem_spread()) {
451 int n = cpuset_mem_spread_node();
452 return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
453 }
454 return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
455}
456EXPORT_SYMBOL(page_cache_alloc_cold);
457#endif
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459/*
460 * In order to wait for pages to become available there must be
461 * waitqueues associated with pages. By using a hash table of
462 * waitqueues where the bucket discipline is to maintain all
463 * waiters on the same queue and wake all when any of the pages
464 * become available, and for the woken contexts to check to be
465 * sure the appropriate page became available, this saves space
466 * at a cost of "thundering herd" phenomena during rare hash
467 * collisions.
468 */
469static wait_queue_head_t *page_waitqueue(struct page *page)
470{
471 const struct zone *zone = page_zone(page);
472
473 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
474}
475
476static inline void wake_up_page(struct page *page, int bit)
477{
478 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
479}
480
481void fastcall wait_on_page_bit(struct page *page, int bit_nr)
482{
483 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
484
485 if (test_bit(bit_nr, &page->flags))
486 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
487 TASK_UNINTERRUPTIBLE);
488}
489EXPORT_SYMBOL(wait_on_page_bit);
490
491/**
492 * unlock_page() - unlock a locked page
493 *
494 * @page: the page
495 *
496 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
497 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
498 * mechananism between PageLocked pages and PageWriteback pages is shared.
499 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
500 *
501 * The first mb is necessary to safely close the critical section opened by the
502 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
503 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
504 * parallel wait_on_page_locked()).
505 */
506void fastcall unlock_page(struct page *page)
507{
508 smp_mb__before_clear_bit();
509 if (!TestClearPageLocked(page))
510 BUG();
511 smp_mb__after_clear_bit();
512 wake_up_page(page, PG_locked);
513}
514EXPORT_SYMBOL(unlock_page);
515
516/*
517 * End writeback against a page.
518 */
519void end_page_writeback(struct page *page)
520{
521 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
522 if (!test_clear_page_writeback(page))
523 BUG();
524 }
525 smp_mb__after_clear_bit();
526 wake_up_page(page, PG_writeback);
527}
528EXPORT_SYMBOL(end_page_writeback);
529
530/*
531 * Get a lock on the page, assuming we need to sleep to get it.
532 *
533 * Ugly: running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
534 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
535 * chances are that on the second loop, the block layer's plug list is empty,
536 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
537 */
538void fastcall __lock_page(struct page *page)
539{
540 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
541
542 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
543 TASK_UNINTERRUPTIBLE);
544}
545EXPORT_SYMBOL(__lock_page);
546
547/*
548 * a rather lightweight function, finding and getting a reference to a
549 * hashed page atomically.
550 */
551struct page * find_get_page(struct address_space *mapping, unsigned long offset)
552{
553 struct page *page;
554
555 read_lock_irq(&mapping->tree_lock);
556 page = radix_tree_lookup(&mapping->page_tree, offset);
557 if (page)
558 page_cache_get(page);
559 read_unlock_irq(&mapping->tree_lock);
560 return page;
561}
562
563EXPORT_SYMBOL(find_get_page);
564
565/*
566 * Same as above, but trylock it instead of incrementing the count.
567 */
568struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
569{
570 struct page *page;
571
572 read_lock_irq(&mapping->tree_lock);
573 page = radix_tree_lookup(&mapping->page_tree, offset);
574 if (page && TestSetPageLocked(page))
575 page = NULL;
576 read_unlock_irq(&mapping->tree_lock);
577 return page;
578}
579
580EXPORT_SYMBOL(find_trylock_page);
581
582/**
583 * find_lock_page - locate, pin and lock a pagecache page
584 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700585 * @mapping: the address_space to search
586 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 *
588 * Locates the desired pagecache page, locks it, increments its reference
589 * count and returns its address.
590 *
591 * Returns zero if the page was not present. find_lock_page() may sleep.
592 */
593struct page *find_lock_page(struct address_space *mapping,
594 unsigned long offset)
595{
596 struct page *page;
597
598 read_lock_irq(&mapping->tree_lock);
599repeat:
600 page = radix_tree_lookup(&mapping->page_tree, offset);
601 if (page) {
602 page_cache_get(page);
603 if (TestSetPageLocked(page)) {
604 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800605 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 read_lock_irq(&mapping->tree_lock);
607
608 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800609 if (unlikely(page->mapping != mapping ||
610 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 unlock_page(page);
612 page_cache_release(page);
613 goto repeat;
614 }
615 }
616 }
617 read_unlock_irq(&mapping->tree_lock);
618 return page;
619}
620
621EXPORT_SYMBOL(find_lock_page);
622
623/**
624 * find_or_create_page - locate or add a pagecache page
625 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700626 * @mapping: the page's address_space
627 * @index: the page's index into the mapping
628 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 *
630 * Locates a page in the pagecache. If the page is not present, a new page
631 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
632 * LRU list. The returned page is locked and has its reference count
633 * incremented.
634 *
635 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
636 * allocation!
637 *
638 * find_or_create_page() returns the desired page's address, or zero on
639 * memory exhaustion.
640 */
641struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400642 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643{
644 struct page *page, *cached_page = NULL;
645 int err;
646repeat:
647 page = find_lock_page(mapping, index);
648 if (!page) {
649 if (!cached_page) {
650 cached_page = alloc_page(gfp_mask);
651 if (!cached_page)
652 return NULL;
653 }
654 err = add_to_page_cache_lru(cached_page, mapping,
655 index, gfp_mask);
656 if (!err) {
657 page = cached_page;
658 cached_page = NULL;
659 } else if (err == -EEXIST)
660 goto repeat;
661 }
662 if (cached_page)
663 page_cache_release(cached_page);
664 return page;
665}
666
667EXPORT_SYMBOL(find_or_create_page);
668
669/**
670 * find_get_pages - gang pagecache lookup
671 * @mapping: The address_space to search
672 * @start: The starting page index
673 * @nr_pages: The maximum number of pages
674 * @pages: Where the resulting pages are placed
675 *
676 * find_get_pages() will search for and return a group of up to
677 * @nr_pages pages in the mapping. The pages are placed at @pages.
678 * find_get_pages() takes a reference against the returned pages.
679 *
680 * The search returns a group of mapping-contiguous pages with ascending
681 * indexes. There may be holes in the indices due to not-present pages.
682 *
683 * find_get_pages() returns the number of pages which were found.
684 */
685unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
686 unsigned int nr_pages, struct page **pages)
687{
688 unsigned int i;
689 unsigned int ret;
690
691 read_lock_irq(&mapping->tree_lock);
692 ret = radix_tree_gang_lookup(&mapping->page_tree,
693 (void **)pages, start, nr_pages);
694 for (i = 0; i < ret; i++)
695 page_cache_get(pages[i]);
696 read_unlock_irq(&mapping->tree_lock);
697 return ret;
698}
699
Jens Axboeebf43502006-04-27 08:46:01 +0200700/**
701 * find_get_pages_contig - gang contiguous pagecache lookup
702 * @mapping: The address_space to search
703 * @index: The starting page index
704 * @nr_pages: The maximum number of pages
705 * @pages: Where the resulting pages are placed
706 *
707 * find_get_pages_contig() works exactly like find_get_pages(), except
708 * that the returned number of pages are guaranteed to be contiguous.
709 *
710 * find_get_pages_contig() returns the number of pages which were found.
711 */
712unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
713 unsigned int nr_pages, struct page **pages)
714{
715 unsigned int i;
716 unsigned int ret;
717
718 read_lock_irq(&mapping->tree_lock);
719 ret = radix_tree_gang_lookup(&mapping->page_tree,
720 (void **)pages, index, nr_pages);
721 for (i = 0; i < ret; i++) {
722 if (pages[i]->mapping == NULL || pages[i]->index != index)
723 break;
724
725 page_cache_get(pages[i]);
726 index++;
727 }
728 read_unlock_irq(&mapping->tree_lock);
729 return i;
730}
731
Linus Torvalds1da177e2005-04-16 15:20:36 -0700732/*
733 * Like find_get_pages, except we only return pages which are tagged with
734 * `tag'. We update *index to index the next page for the traversal.
735 */
736unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
737 int tag, unsigned int nr_pages, struct page **pages)
738{
739 unsigned int i;
740 unsigned int ret;
741
742 read_lock_irq(&mapping->tree_lock);
743 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
744 (void **)pages, *index, nr_pages, tag);
745 for (i = 0; i < ret; i++)
746 page_cache_get(pages[i]);
747 if (ret)
748 *index = pages[ret - 1]->index + 1;
749 read_unlock_irq(&mapping->tree_lock);
750 return ret;
751}
752
753/*
754 * Same as grab_cache_page, but do not wait if the page is unavailable.
755 * This is intended for speculative data generators, where the data can
756 * be regenerated if the page couldn't be grabbed. This routine should
757 * be safe to call while holding the lock for another page.
758 *
759 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
760 * and deadlock against the caller's locked page.
761 */
762struct page *
763grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
764{
765 struct page *page = find_get_page(mapping, index);
Al Viro6daa0e22005-10-21 03:18:50 -0400766 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767
768 if (page) {
769 if (!TestSetPageLocked(page))
770 return page;
771 page_cache_release(page);
772 return NULL;
773 }
774 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
775 page = alloc_pages(gfp_mask, 0);
776 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
777 page_cache_release(page);
778 page = NULL;
779 }
780 return page;
781}
782
783EXPORT_SYMBOL(grab_cache_page_nowait);
784
785/*
786 * This is a generic file read routine, and uses the
787 * mapping->a_ops->readpage() function for the actual low-level
788 * stuff.
789 *
790 * This is really ugly. But the goto's actually try to clarify some
791 * of the logic when it comes to error handling etc.
792 *
793 * Note the struct file* is only passed for the use of readpage. It may be
794 * NULL.
795 */
796void do_generic_mapping_read(struct address_space *mapping,
797 struct file_ra_state *_ra,
798 struct file *filp,
799 loff_t *ppos,
800 read_descriptor_t *desc,
801 read_actor_t actor)
802{
803 struct inode *inode = mapping->host;
804 unsigned long index;
805 unsigned long end_index;
806 unsigned long offset;
807 unsigned long last_index;
808 unsigned long next_index;
809 unsigned long prev_index;
810 loff_t isize;
811 struct page *cached_page;
812 int error;
813 struct file_ra_state ra = *_ra;
814
815 cached_page = NULL;
816 index = *ppos >> PAGE_CACHE_SHIFT;
817 next_index = index;
818 prev_index = ra.prev_page;
819 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
820 offset = *ppos & ~PAGE_CACHE_MASK;
821
822 isize = i_size_read(inode);
823 if (!isize)
824 goto out;
825
826 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
827 for (;;) {
828 struct page *page;
829 unsigned long nr, ret;
830
831 /* nr is the maximum number of bytes to copy from this page */
832 nr = PAGE_CACHE_SIZE;
833 if (index >= end_index) {
834 if (index > end_index)
835 goto out;
836 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
837 if (nr <= offset) {
838 goto out;
839 }
840 }
841 nr = nr - offset;
842
843 cond_resched();
844 if (index == next_index)
845 next_index = page_cache_readahead(mapping, &ra, filp,
846 index, last_index - index);
847
848find_page:
849 page = find_get_page(mapping, index);
850 if (unlikely(page == NULL)) {
851 handle_ra_miss(mapping, &ra, index);
852 goto no_cached_page;
853 }
854 if (!PageUptodate(page))
855 goto page_not_up_to_date;
856page_ok:
857
858 /* If users can be writing to this page using arbitrary
859 * virtual addresses, take care about potential aliasing
860 * before reading the page on the kernel side.
861 */
862 if (mapping_writably_mapped(mapping))
863 flush_dcache_page(page);
864
865 /*
866 * When (part of) the same page is read multiple times
867 * in succession, only mark it as accessed the first time.
868 */
869 if (prev_index != index)
870 mark_page_accessed(page);
871 prev_index = index;
872
873 /*
874 * Ok, we have the page, and it's up-to-date, so
875 * now we can copy it to user space...
876 *
877 * The actor routine returns how many bytes were actually used..
878 * NOTE! This may not be the same as how much of a user buffer
879 * we filled up (we may be padding etc), so we can only update
880 * "pos" here (the actor routine has to update the user buffer
881 * pointers and the remaining count).
882 */
883 ret = actor(desc, page, offset, nr);
884 offset += ret;
885 index += offset >> PAGE_CACHE_SHIFT;
886 offset &= ~PAGE_CACHE_MASK;
887
888 page_cache_release(page);
889 if (ret == nr && desc->count)
890 continue;
891 goto out;
892
893page_not_up_to_date:
894 /* Get exclusive access to the page ... */
895 lock_page(page);
896
897 /* Did it get unhashed before we got the lock? */
898 if (!page->mapping) {
899 unlock_page(page);
900 page_cache_release(page);
901 continue;
902 }
903
904 /* Did somebody else fill it already? */
905 if (PageUptodate(page)) {
906 unlock_page(page);
907 goto page_ok;
908 }
909
910readpage:
911 /* Start the actual read. The read will unlock the page. */
912 error = mapping->a_ops->readpage(filp, page);
913
Zach Brown994fc28c2005-12-15 14:28:17 -0800914 if (unlikely(error)) {
915 if (error == AOP_TRUNCATED_PAGE) {
916 page_cache_release(page);
917 goto find_page;
918 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800920 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
922 if (!PageUptodate(page)) {
923 lock_page(page);
924 if (!PageUptodate(page)) {
925 if (page->mapping == NULL) {
926 /*
927 * invalidate_inode_pages got it
928 */
929 unlock_page(page);
930 page_cache_release(page);
931 goto find_page;
932 }
933 unlock_page(page);
934 error = -EIO;
935 goto readpage_error;
936 }
937 unlock_page(page);
938 }
939
940 /*
941 * i_size must be checked after we have done ->readpage.
942 *
943 * Checking i_size after the readpage allows us to calculate
944 * the correct value for "nr", which means the zero-filled
945 * part of the page is not copied back to userspace (unless
946 * another truncate extends the file - this is desired though).
947 */
948 isize = i_size_read(inode);
949 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
950 if (unlikely(!isize || index > end_index)) {
951 page_cache_release(page);
952 goto out;
953 }
954
955 /* nr is the maximum number of bytes to copy from this page */
956 nr = PAGE_CACHE_SIZE;
957 if (index == end_index) {
958 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
959 if (nr <= offset) {
960 page_cache_release(page);
961 goto out;
962 }
963 }
964 nr = nr - offset;
965 goto page_ok;
966
967readpage_error:
968 /* UHHUH! A synchronous read error occurred. Report it */
969 desc->error = error;
970 page_cache_release(page);
971 goto out;
972
973no_cached_page:
974 /*
975 * Ok, it wasn't cached, so we need to create a new
976 * page..
977 */
978 if (!cached_page) {
979 cached_page = page_cache_alloc_cold(mapping);
980 if (!cached_page) {
981 desc->error = -ENOMEM;
982 goto out;
983 }
984 }
985 error = add_to_page_cache_lru(cached_page, mapping,
986 index, GFP_KERNEL);
987 if (error) {
988 if (error == -EEXIST)
989 goto find_page;
990 desc->error = error;
991 goto out;
992 }
993 page = cached_page;
994 cached_page = NULL;
995 goto readpage;
996 }
997
998out:
999 *_ra = ra;
1000
1001 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1002 if (cached_page)
1003 page_cache_release(cached_page);
1004 if (filp)
1005 file_accessed(filp);
1006}
1007
1008EXPORT_SYMBOL(do_generic_mapping_read);
1009
1010int file_read_actor(read_descriptor_t *desc, struct page *page,
1011 unsigned long offset, unsigned long size)
1012{
1013 char *kaddr;
1014 unsigned long left, count = desc->count;
1015
1016 if (size > count)
1017 size = count;
1018
1019 /*
1020 * Faults on the destination of a read are common, so do it before
1021 * taking the kmap.
1022 */
1023 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1024 kaddr = kmap_atomic(page, KM_USER0);
1025 left = __copy_to_user_inatomic(desc->arg.buf,
1026 kaddr + offset, size);
1027 kunmap_atomic(kaddr, KM_USER0);
1028 if (left == 0)
1029 goto success;
1030 }
1031
1032 /* Do it the slow way */
1033 kaddr = kmap(page);
1034 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1035 kunmap(page);
1036
1037 if (left) {
1038 size -= left;
1039 desc->error = -EFAULT;
1040 }
1041success:
1042 desc->count = count - size;
1043 desc->written += size;
1044 desc->arg.buf += size;
1045 return size;
1046}
Steven Whitehousebf9f4242006-06-21 11:54:43 -04001047EXPORT_SYMBOL_GPL(file_read_actor);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
1049/*
1050 * This is the "read()" routine for all filesystems
1051 * that can use the page cache directly.
1052 */
1053ssize_t
1054__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1055 unsigned long nr_segs, loff_t *ppos)
1056{
1057 struct file *filp = iocb->ki_filp;
1058 ssize_t retval;
1059 unsigned long seg;
1060 size_t count;
1061
1062 count = 0;
1063 for (seg = 0; seg < nr_segs; seg++) {
1064 const struct iovec *iv = &iov[seg];
1065
1066 /*
1067 * If any segment has a negative length, or the cumulative
1068 * length ever wraps negative then return -EINVAL.
1069 */
1070 count += iv->iov_len;
1071 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1072 return -EINVAL;
1073 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1074 continue;
1075 if (seg == 0)
1076 return -EFAULT;
1077 nr_segs = seg;
1078 count -= iv->iov_len; /* This segment is no good */
1079 break;
1080 }
1081
1082 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1083 if (filp->f_flags & O_DIRECT) {
1084 loff_t pos = *ppos, size;
1085 struct address_space *mapping;
1086 struct inode *inode;
1087
1088 mapping = filp->f_mapping;
1089 inode = mapping->host;
1090 retval = 0;
1091 if (!count)
1092 goto out; /* skip atime */
1093 size = i_size_read(inode);
1094 if (pos < size) {
1095 retval = generic_file_direct_IO(READ, iocb,
1096 iov, pos, nr_segs);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001097 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098 retval = -EIOCBQUEUED;
1099 if (retval > 0)
1100 *ppos = pos + retval;
1101 }
1102 file_accessed(filp);
1103 goto out;
1104 }
1105
1106 retval = 0;
1107 if (count) {
1108 for (seg = 0; seg < nr_segs; seg++) {
1109 read_descriptor_t desc;
1110
1111 desc.written = 0;
1112 desc.arg.buf = iov[seg].iov_base;
1113 desc.count = iov[seg].iov_len;
1114 if (desc.count == 0)
1115 continue;
1116 desc.error = 0;
1117 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1118 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001119 if (desc.error) {
1120 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 break;
1122 }
1123 }
1124 }
1125out:
1126 return retval;
1127}
1128
1129EXPORT_SYMBOL(__generic_file_aio_read);
1130
1131ssize_t
1132generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1133{
1134 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1135
1136 BUG_ON(iocb->ki_pos != pos);
1137 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1138}
1139
1140EXPORT_SYMBOL(generic_file_aio_read);
1141
1142ssize_t
1143generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1144{
1145 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1146 struct kiocb kiocb;
1147 ssize_t ret;
1148
1149 init_sync_kiocb(&kiocb, filp);
1150 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1151 if (-EIOCBQUEUED == ret)
1152 ret = wait_on_sync_kiocb(&kiocb);
1153 return ret;
1154}
1155
1156EXPORT_SYMBOL(generic_file_read);
1157
1158int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1159{
1160 ssize_t written;
1161 unsigned long count = desc->count;
1162 struct file *file = desc->arg.data;
1163
1164 if (size > count)
1165 size = count;
1166
1167 written = file->f_op->sendpage(file, page, offset,
1168 size, &file->f_pos, size<count);
1169 if (written < 0) {
1170 desc->error = written;
1171 written = 0;
1172 }
1173 desc->count = count - written;
1174 desc->written += written;
1175 return written;
1176}
1177
1178ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1179 size_t count, read_actor_t actor, void *target)
1180{
1181 read_descriptor_t desc;
1182
1183 if (!count)
1184 return 0;
1185
1186 desc.written = 0;
1187 desc.count = count;
1188 desc.arg.data = target;
1189 desc.error = 0;
1190
1191 do_generic_file_read(in_file, ppos, &desc, actor);
1192 if (desc.written)
1193 return desc.written;
1194 return desc.error;
1195}
1196
1197EXPORT_SYMBOL(generic_file_sendfile);
1198
1199static ssize_t
1200do_readahead(struct address_space *mapping, struct file *filp,
1201 unsigned long index, unsigned long nr)
1202{
1203 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1204 return -EINVAL;
1205
1206 force_page_cache_readahead(mapping, filp, index,
1207 max_sane_readahead(nr));
1208 return 0;
1209}
1210
1211asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1212{
1213 ssize_t ret;
1214 struct file *file;
1215
1216 ret = -EBADF;
1217 file = fget(fd);
1218 if (file) {
1219 if (file->f_mode & FMODE_READ) {
1220 struct address_space *mapping = file->f_mapping;
1221 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1222 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1223 unsigned long len = end - start + 1;
1224 ret = do_readahead(mapping, file, start, len);
1225 }
1226 fput(file);
1227 }
1228 return ret;
1229}
1230
1231#ifdef CONFIG_MMU
1232/*
1233 * This adds the requested page to the page cache if it isn't already there,
1234 * and schedules an I/O to read in its contents from disk.
1235 */
1236static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1237static int fastcall page_cache_read(struct file * file, unsigned long offset)
1238{
1239 struct address_space *mapping = file->f_mapping;
1240 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001241 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242
Zach Brown994fc28c2005-12-15 14:28:17 -08001243 do {
1244 page = page_cache_alloc_cold(mapping);
1245 if (!page)
1246 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247
Zach Brown994fc28c2005-12-15 14:28:17 -08001248 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1249 if (ret == 0)
1250 ret = mapping->a_ops->readpage(file, page);
1251 else if (ret == -EEXIST)
1252 ret = 0; /* losing race to add is OK */
1253
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255
Zach Brown994fc28c2005-12-15 14:28:17 -08001256 } while (ret == AOP_TRUNCATED_PAGE);
1257
1258 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259}
1260
1261#define MMAP_LOTSAMISS (100)
1262
1263/*
1264 * filemap_nopage() is invoked via the vma operations vector for a
1265 * mapped memory region to read in file data during a page fault.
1266 *
1267 * The goto's are kind of ugly, but this streamlines the normal case of having
1268 * it in the page cache, and handles the special cases reasonably without
1269 * having a lot of duplicated code.
1270 */
1271struct page *filemap_nopage(struct vm_area_struct *area,
1272 unsigned long address, int *type)
1273{
1274 int error;
1275 struct file *file = area->vm_file;
1276 struct address_space *mapping = file->f_mapping;
1277 struct file_ra_state *ra = &file->f_ra;
1278 struct inode *inode = mapping->host;
1279 struct page *page;
1280 unsigned long size, pgoff;
1281 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1282
1283 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1284
1285retry_all:
1286 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1287 if (pgoff >= size)
1288 goto outside_data_content;
1289
1290 /* If we don't want any read-ahead, don't bother */
1291 if (VM_RandomReadHint(area))
1292 goto no_cached_page;
1293
1294 /*
1295 * The readahead code wants to be told about each and every page
1296 * so it can build and shrink its windows appropriately
1297 *
1298 * For sequential accesses, we use the generic readahead logic.
1299 */
1300 if (VM_SequentialReadHint(area))
1301 page_cache_readahead(mapping, ra, file, pgoff, 1);
1302
1303 /*
1304 * Do we have something in the page cache already?
1305 */
1306retry_find:
1307 page = find_get_page(mapping, pgoff);
1308 if (!page) {
1309 unsigned long ra_pages;
1310
1311 if (VM_SequentialReadHint(area)) {
1312 handle_ra_miss(mapping, ra, pgoff);
1313 goto no_cached_page;
1314 }
1315 ra->mmap_miss++;
1316
1317 /*
1318 * Do we miss much more than hit in this file? If so,
1319 * stop bothering with read-ahead. It will only hurt.
1320 */
1321 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1322 goto no_cached_page;
1323
1324 /*
1325 * To keep the pgmajfault counter straight, we need to
1326 * check did_readaround, as this is an inner loop.
1327 */
1328 if (!did_readaround) {
1329 majmin = VM_FAULT_MAJOR;
1330 inc_page_state(pgmajfault);
1331 }
1332 did_readaround = 1;
1333 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1334 if (ra_pages) {
1335 pgoff_t start = 0;
1336
1337 if (pgoff > ra_pages / 2)
1338 start = pgoff - ra_pages / 2;
1339 do_page_cache_readahead(mapping, file, start, ra_pages);
1340 }
1341 page = find_get_page(mapping, pgoff);
1342 if (!page)
1343 goto no_cached_page;
1344 }
1345
1346 if (!did_readaround)
1347 ra->mmap_hit++;
1348
1349 /*
1350 * Ok, found a page in the page cache, now we need to check
1351 * that it's up-to-date.
1352 */
1353 if (!PageUptodate(page))
1354 goto page_not_uptodate;
1355
1356success:
1357 /*
1358 * Found the page and have a reference on it.
1359 */
1360 mark_page_accessed(page);
1361 if (type)
1362 *type = majmin;
1363 return page;
1364
1365outside_data_content:
1366 /*
1367 * An external ptracer can access pages that normally aren't
1368 * accessible..
1369 */
1370 if (area->vm_mm == current->mm)
1371 return NULL;
1372 /* Fall through to the non-read-ahead case */
1373no_cached_page:
1374 /*
1375 * We're only likely to ever get here if MADV_RANDOM is in
1376 * effect.
1377 */
1378 error = page_cache_read(file, pgoff);
1379 grab_swap_token();
1380
1381 /*
1382 * The page we want has now been added to the page cache.
1383 * In the unlikely event that someone removed it in the
1384 * meantime, we'll just come back here and read it again.
1385 */
1386 if (error >= 0)
1387 goto retry_find;
1388
1389 /*
1390 * An error return from page_cache_read can result if the
1391 * system is low on memory, or a problem occurs while trying
1392 * to schedule I/O.
1393 */
1394 if (error == -ENOMEM)
1395 return NOPAGE_OOM;
1396 return NULL;
1397
1398page_not_uptodate:
1399 if (!did_readaround) {
1400 majmin = VM_FAULT_MAJOR;
1401 inc_page_state(pgmajfault);
1402 }
1403 lock_page(page);
1404
1405 /* Did it get unhashed while we waited for it? */
1406 if (!page->mapping) {
1407 unlock_page(page);
1408 page_cache_release(page);
1409 goto retry_all;
1410 }
1411
1412 /* Did somebody else get it up-to-date? */
1413 if (PageUptodate(page)) {
1414 unlock_page(page);
1415 goto success;
1416 }
1417
Zach Brown994fc28c2005-12-15 14:28:17 -08001418 error = mapping->a_ops->readpage(file, page);
1419 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420 wait_on_page_locked(page);
1421 if (PageUptodate(page))
1422 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001423 } else if (error == AOP_TRUNCATED_PAGE) {
1424 page_cache_release(page);
1425 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426 }
1427
1428 /*
1429 * Umm, take care of errors if the page isn't up-to-date.
1430 * Try to re-read it _once_. We do this synchronously,
1431 * because there really aren't any performance issues here
1432 * and we need to check for errors.
1433 */
1434 lock_page(page);
1435
1436 /* Somebody truncated the page on us? */
1437 if (!page->mapping) {
1438 unlock_page(page);
1439 page_cache_release(page);
1440 goto retry_all;
1441 }
1442
1443 /* Somebody else successfully read it in? */
1444 if (PageUptodate(page)) {
1445 unlock_page(page);
1446 goto success;
1447 }
1448 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001449 error = mapping->a_ops->readpage(file, page);
1450 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 wait_on_page_locked(page);
1452 if (PageUptodate(page))
1453 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001454 } else if (error == AOP_TRUNCATED_PAGE) {
1455 page_cache_release(page);
1456 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457 }
1458
1459 /*
1460 * Things didn't work out. Return zero to tell the
1461 * mm layer so, possibly freeing the page cache page first.
1462 */
1463 page_cache_release(page);
1464 return NULL;
1465}
1466
1467EXPORT_SYMBOL(filemap_nopage);
1468
1469static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1470 int nonblock)
1471{
1472 struct address_space *mapping = file->f_mapping;
1473 struct page *page;
1474 int error;
1475
1476 /*
1477 * Do we have something in the page cache already?
1478 */
1479retry_find:
1480 page = find_get_page(mapping, pgoff);
1481 if (!page) {
1482 if (nonblock)
1483 return NULL;
1484 goto no_cached_page;
1485 }
1486
1487 /*
1488 * Ok, found a page in the page cache, now we need to check
1489 * that it's up-to-date.
1490 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001491 if (!PageUptodate(page)) {
1492 if (nonblock) {
1493 page_cache_release(page);
1494 return NULL;
1495 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001497 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498
1499success:
1500 /*
1501 * Found the page and have a reference on it.
1502 */
1503 mark_page_accessed(page);
1504 return page;
1505
1506no_cached_page:
1507 error = page_cache_read(file, pgoff);
1508
1509 /*
1510 * The page we want has now been added to the page cache.
1511 * In the unlikely event that someone removed it in the
1512 * meantime, we'll just come back here and read it again.
1513 */
1514 if (error >= 0)
1515 goto retry_find;
1516
1517 /*
1518 * An error return from page_cache_read can result if the
1519 * system is low on memory, or a problem occurs while trying
1520 * to schedule I/O.
1521 */
1522 return NULL;
1523
1524page_not_uptodate:
1525 lock_page(page);
1526
1527 /* Did it get unhashed while we waited for it? */
1528 if (!page->mapping) {
1529 unlock_page(page);
1530 goto err;
1531 }
1532
1533 /* Did somebody else get it up-to-date? */
1534 if (PageUptodate(page)) {
1535 unlock_page(page);
1536 goto success;
1537 }
1538
Zach Brown994fc28c2005-12-15 14:28:17 -08001539 error = mapping->a_ops->readpage(file, page);
1540 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 wait_on_page_locked(page);
1542 if (PageUptodate(page))
1543 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001544 } else if (error == AOP_TRUNCATED_PAGE) {
1545 page_cache_release(page);
1546 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 }
1548
1549 /*
1550 * Umm, take care of errors if the page isn't up-to-date.
1551 * Try to re-read it _once_. We do this synchronously,
1552 * because there really aren't any performance issues here
1553 * and we need to check for errors.
1554 */
1555 lock_page(page);
1556
1557 /* Somebody truncated the page on us? */
1558 if (!page->mapping) {
1559 unlock_page(page);
1560 goto err;
1561 }
1562 /* Somebody else successfully read it in? */
1563 if (PageUptodate(page)) {
1564 unlock_page(page);
1565 goto success;
1566 }
1567
1568 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001569 error = mapping->a_ops->readpage(file, page);
1570 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 wait_on_page_locked(page);
1572 if (PageUptodate(page))
1573 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001574 } else if (error == AOP_TRUNCATED_PAGE) {
1575 page_cache_release(page);
1576 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001577 }
1578
1579 /*
1580 * Things didn't work out. Return zero to tell the
1581 * mm layer so, possibly freeing the page cache page first.
1582 */
1583err:
1584 page_cache_release(page);
1585
1586 return NULL;
1587}
1588
1589int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1590 unsigned long len, pgprot_t prot, unsigned long pgoff,
1591 int nonblock)
1592{
1593 struct file *file = vma->vm_file;
1594 struct address_space *mapping = file->f_mapping;
1595 struct inode *inode = mapping->host;
1596 unsigned long size;
1597 struct mm_struct *mm = vma->vm_mm;
1598 struct page *page;
1599 int err;
1600
1601 if (!nonblock)
1602 force_page_cache_readahead(mapping, vma->vm_file,
1603 pgoff, len >> PAGE_CACHE_SHIFT);
1604
1605repeat:
1606 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1607 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1608 return -EINVAL;
1609
1610 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001611
1612 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1613 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 if (!page && !nonblock)
1615 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001616
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 if (page) {
1618 err = install_page(mm, vma, addr, page, prot);
1619 if (err) {
1620 page_cache_release(page);
1621 return err;
1622 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001623 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001624 /* No page was found just because we can't read it in now (being
1625 * here implies nonblock != 0), but the page may exist, so set
1626 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 err = install_file_pte(mm, vma, addr, pgoff, prot);
1628 if (err)
1629 return err;
1630 }
1631
1632 len -= PAGE_SIZE;
1633 addr += PAGE_SIZE;
1634 pgoff++;
1635 if (len)
1636 goto repeat;
1637
1638 return 0;
1639}
Nikita Danilovb1459462005-10-29 18:17:02 -07001640EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641
1642struct vm_operations_struct generic_file_vm_ops = {
1643 .nopage = filemap_nopage,
1644 .populate = filemap_populate,
1645};
1646
1647/* This is used for a general mmap of a disk file */
1648
1649int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1650{
1651 struct address_space *mapping = file->f_mapping;
1652
1653 if (!mapping->a_ops->readpage)
1654 return -ENOEXEC;
1655 file_accessed(file);
1656 vma->vm_ops = &generic_file_vm_ops;
1657 return 0;
1658}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659
1660/*
1661 * This is for filesystems which do not implement ->writepage.
1662 */
1663int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1664{
1665 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1666 return -EINVAL;
1667 return generic_file_mmap(file, vma);
1668}
1669#else
1670int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1671{
1672 return -ENOSYS;
1673}
1674int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1675{
1676 return -ENOSYS;
1677}
1678#endif /* CONFIG_MMU */
1679
1680EXPORT_SYMBOL(generic_file_mmap);
1681EXPORT_SYMBOL(generic_file_readonly_mmap);
1682
1683static inline struct page *__read_cache_page(struct address_space *mapping,
1684 unsigned long index,
1685 int (*filler)(void *,struct page*),
1686 void *data)
1687{
1688 struct page *page, *cached_page = NULL;
1689 int err;
1690repeat:
1691 page = find_get_page(mapping, index);
1692 if (!page) {
1693 if (!cached_page) {
1694 cached_page = page_cache_alloc_cold(mapping);
1695 if (!cached_page)
1696 return ERR_PTR(-ENOMEM);
1697 }
1698 err = add_to_page_cache_lru(cached_page, mapping,
1699 index, GFP_KERNEL);
1700 if (err == -EEXIST)
1701 goto repeat;
1702 if (err < 0) {
1703 /* Presumably ENOMEM for radix tree node */
1704 page_cache_release(cached_page);
1705 return ERR_PTR(err);
1706 }
1707 page = cached_page;
1708 cached_page = NULL;
1709 err = filler(data, page);
1710 if (err < 0) {
1711 page_cache_release(page);
1712 page = ERR_PTR(err);
1713 }
1714 }
1715 if (cached_page)
1716 page_cache_release(cached_page);
1717 return page;
1718}
1719
1720/*
1721 * Read into the page cache. If a page already exists,
1722 * and PageUptodate() is not set, try to fill the page.
1723 */
1724struct page *read_cache_page(struct address_space *mapping,
1725 unsigned long index,
1726 int (*filler)(void *,struct page*),
1727 void *data)
1728{
1729 struct page *page;
1730 int err;
1731
1732retry:
1733 page = __read_cache_page(mapping, index, filler, data);
1734 if (IS_ERR(page))
1735 goto out;
1736 mark_page_accessed(page);
1737 if (PageUptodate(page))
1738 goto out;
1739
1740 lock_page(page);
1741 if (!page->mapping) {
1742 unlock_page(page);
1743 page_cache_release(page);
1744 goto retry;
1745 }
1746 if (PageUptodate(page)) {
1747 unlock_page(page);
1748 goto out;
1749 }
1750 err = filler(data, page);
1751 if (err < 0) {
1752 page_cache_release(page);
1753 page = ERR_PTR(err);
1754 }
1755 out:
1756 return page;
1757}
1758
1759EXPORT_SYMBOL(read_cache_page);
1760
1761/*
1762 * If the page was newly created, increment its refcount and add it to the
1763 * caller's lru-buffering pagevec. This function is specifically for
1764 * generic_file_write().
1765 */
1766static inline struct page *
1767__grab_cache_page(struct address_space *mapping, unsigned long index,
1768 struct page **cached_page, struct pagevec *lru_pvec)
1769{
1770 int err;
1771 struct page *page;
1772repeat:
1773 page = find_lock_page(mapping, index);
1774 if (!page) {
1775 if (!*cached_page) {
1776 *cached_page = page_cache_alloc(mapping);
1777 if (!*cached_page)
1778 return NULL;
1779 }
1780 err = add_to_page_cache(*cached_page, mapping,
1781 index, GFP_KERNEL);
1782 if (err == -EEXIST)
1783 goto repeat;
1784 if (err == 0) {
1785 page = *cached_page;
1786 page_cache_get(page);
1787 if (!pagevec_add(lru_pvec, page))
1788 __pagevec_lru_add(lru_pvec);
1789 *cached_page = NULL;
1790 }
1791 }
1792 return page;
1793}
1794
1795/*
1796 * The logic we want is
1797 *
1798 * if suid or (sgid and xgrp)
1799 * remove privs
1800 */
1801int remove_suid(struct dentry *dentry)
1802{
1803 mode_t mode = dentry->d_inode->i_mode;
1804 int kill = 0;
1805 int result = 0;
1806
1807 /* suid always must be killed */
1808 if (unlikely(mode & S_ISUID))
1809 kill = ATTR_KILL_SUID;
1810
1811 /*
1812 * sgid without any exec bits is just a mandatory locking mark; leave
1813 * it alone. If some exec bits are set, it's a real sgid; kill it.
1814 */
1815 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1816 kill |= ATTR_KILL_SGID;
1817
1818 if (unlikely(kill && !capable(CAP_FSETID))) {
1819 struct iattr newattrs;
1820
1821 newattrs.ia_valid = ATTR_FORCE | kill;
1822 result = notify_change(dentry, &newattrs);
1823 }
1824 return result;
1825}
1826EXPORT_SYMBOL(remove_suid);
1827
Carsten Otteceffc072005-06-23 22:05:25 -07001828size_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829__filemap_copy_from_user_iovec(char *vaddr,
1830 const struct iovec *iov, size_t base, size_t bytes)
1831{
1832 size_t copied = 0, left = 0;
1833
1834 while (bytes) {
1835 char __user *buf = iov->iov_base + base;
1836 int copy = min(bytes, iov->iov_len - base);
1837
1838 base = 0;
1839 left = __copy_from_user_inatomic(vaddr, buf, copy);
1840 copied += copy;
1841 bytes -= copy;
1842 vaddr += copy;
1843 iov++;
1844
1845 if (unlikely(left)) {
1846 /* zero the rest of the target like __copy_from_user */
1847 if (bytes)
1848 memset(vaddr, 0, bytes);
1849 break;
1850 }
1851 }
1852 return copied - left;
1853}
1854
1855/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 * Performs necessary checks before doing a write
1857 *
1858 * Can adjust writing position aor amount of bytes to write.
1859 * Returns appropriate error code that caller should return or
1860 * zero in case that write should be allowed.
1861 */
1862inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1863{
1864 struct inode *inode = file->f_mapping->host;
1865 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1866
1867 if (unlikely(*pos < 0))
1868 return -EINVAL;
1869
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870 if (!isblk) {
1871 /* FIXME: this is for backwards compatibility with 2.4 */
1872 if (file->f_flags & O_APPEND)
1873 *pos = i_size_read(inode);
1874
1875 if (limit != RLIM_INFINITY) {
1876 if (*pos >= limit) {
1877 send_sig(SIGXFSZ, current, 0);
1878 return -EFBIG;
1879 }
1880 if (*count > limit - (typeof(limit))*pos) {
1881 *count = limit - (typeof(limit))*pos;
1882 }
1883 }
1884 }
1885
1886 /*
1887 * LFS rule
1888 */
1889 if (unlikely(*pos + *count > MAX_NON_LFS &&
1890 !(file->f_flags & O_LARGEFILE))) {
1891 if (*pos >= MAX_NON_LFS) {
1892 send_sig(SIGXFSZ, current, 0);
1893 return -EFBIG;
1894 }
1895 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1896 *count = MAX_NON_LFS - (unsigned long)*pos;
1897 }
1898 }
1899
1900 /*
1901 * Are we about to exceed the fs block limit ?
1902 *
1903 * If we have written data it becomes a short write. If we have
1904 * exceeded without writing data we send a signal and return EFBIG.
1905 * Linus frestrict idea will clean these up nicely..
1906 */
1907 if (likely(!isblk)) {
1908 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1909 if (*count || *pos > inode->i_sb->s_maxbytes) {
1910 send_sig(SIGXFSZ, current, 0);
1911 return -EFBIG;
1912 }
1913 /* zero-length writes at ->s_maxbytes are OK */
1914 }
1915
1916 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1917 *count = inode->i_sb->s_maxbytes - *pos;
1918 } else {
1919 loff_t isize;
1920 if (bdev_read_only(I_BDEV(inode)))
1921 return -EPERM;
1922 isize = i_size_read(inode);
1923 if (*pos >= isize) {
1924 if (*count || *pos > isize)
1925 return -ENOSPC;
1926 }
1927
1928 if (*pos + *count > isize)
1929 *count = isize - *pos;
1930 }
1931 return 0;
1932}
1933EXPORT_SYMBOL(generic_write_checks);
1934
1935ssize_t
1936generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1937 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1938 size_t count, size_t ocount)
1939{
1940 struct file *file = iocb->ki_filp;
1941 struct address_space *mapping = file->f_mapping;
1942 struct inode *inode = mapping->host;
1943 ssize_t written;
1944
1945 if (count != ocount)
1946 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1947
1948 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1949 if (written > 0) {
1950 loff_t end = pos + written;
1951 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1952 i_size_write(inode, end);
1953 mark_inode_dirty(inode);
1954 }
1955 *ppos = end;
1956 }
1957
1958 /*
1959 * Sync the fs metadata but not the minor inode changes and
1960 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001961 * i_mutex is held, which protects generic_osync_inode() from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001962 * livelocking.
1963 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07001964 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
1965 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1966 if (err < 0)
1967 written = err;
1968 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969 if (written == count && !is_sync_kiocb(iocb))
1970 written = -EIOCBQUEUED;
1971 return written;
1972}
1973EXPORT_SYMBOL(generic_file_direct_write);
1974
1975ssize_t
1976generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
1977 unsigned long nr_segs, loff_t pos, loff_t *ppos,
1978 size_t count, ssize_t written)
1979{
1980 struct file *file = iocb->ki_filp;
1981 struct address_space * mapping = file->f_mapping;
1982 struct address_space_operations *a_ops = mapping->a_ops;
1983 struct inode *inode = mapping->host;
1984 long status = 0;
1985 struct page *page;
1986 struct page *cached_page = NULL;
1987 size_t bytes;
1988 struct pagevec lru_pvec;
1989 const struct iovec *cur_iov = iov; /* current iovec */
1990 size_t iov_base = 0; /* offset in the current iovec */
1991 char __user *buf;
1992
1993 pagevec_init(&lru_pvec, 0);
1994
1995 /*
1996 * handle partial DIO write. Adjust cur_iov if needed.
1997 */
1998 if (likely(nr_segs == 1))
1999 buf = iov->iov_base + written;
2000 else {
2001 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002002 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002003 }
2004
2005 do {
2006 unsigned long index;
2007 unsigned long offset;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002008 unsigned long maxlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002009 size_t copied;
2010
2011 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2012 index = pos >> PAGE_CACHE_SHIFT;
2013 bytes = PAGE_CACHE_SIZE - offset;
2014 if (bytes > count)
2015 bytes = count;
2016
2017 /*
2018 * Bring in the user page that we will copy from _first_.
2019 * Otherwise there's a nasty deadlock on copying from the
2020 * same page as we're writing to, without it being marked
2021 * up-to-date.
2022 */
Martin Schwidefskya5117182005-06-06 13:35:54 -07002023 maxlen = cur_iov->iov_len - iov_base;
2024 if (maxlen > bytes)
2025 maxlen = bytes;
2026 fault_in_pages_readable(buf, maxlen);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027
2028 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2029 if (!page) {
2030 status = -ENOMEM;
2031 break;
2032 }
2033
2034 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2035 if (unlikely(status)) {
2036 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08002037
2038 if (status != AOP_TRUNCATED_PAGE)
2039 unlock_page(page);
2040 page_cache_release(page);
2041 if (status == AOP_TRUNCATED_PAGE)
2042 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 /*
2044 * prepare_write() may have instantiated a few blocks
2045 * outside i_size. Trim these off again.
2046 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047 if (pos + bytes > isize)
2048 vmtruncate(inode, isize);
2049 break;
2050 }
2051 if (likely(nr_segs == 1))
2052 copied = filemap_copy_from_user(page, offset,
2053 buf, bytes);
2054 else
2055 copied = filemap_copy_from_user_iovec(page, offset,
2056 cur_iov, iov_base, bytes);
2057 flush_dcache_page(page);
2058 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08002059 if (status == AOP_TRUNCATED_PAGE) {
2060 page_cache_release(page);
2061 continue;
2062 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 if (likely(copied > 0)) {
2064 if (!status)
2065 status = copied;
2066
2067 if (status >= 0) {
2068 written += status;
2069 count -= status;
2070 pos += status;
2071 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002072 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002073 filemap_set_next_iovec(&cur_iov,
2074 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002075 if (count)
2076 buf = cur_iov->iov_base +
2077 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002078 } else {
2079 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002080 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 }
2082 }
2083 if (unlikely(copied != bytes))
2084 if (status >= 0)
2085 status = -EFAULT;
2086 unlock_page(page);
2087 mark_page_accessed(page);
2088 page_cache_release(page);
2089 if (status < 0)
2090 break;
2091 balance_dirty_pages_ratelimited(mapping);
2092 cond_resched();
2093 } while (count);
2094 *ppos = pos;
2095
2096 if (cached_page)
2097 page_cache_release(cached_page);
2098
2099 /*
2100 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2101 */
2102 if (likely(status >= 0)) {
2103 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2104 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2105 status = generic_osync_inode(inode, mapping,
2106 OSYNC_METADATA|OSYNC_DATA);
2107 }
2108 }
2109
2110 /*
2111 * If we get here for O_DIRECT writes then we must have fallen through
2112 * to buffered writes (block instantiation inside i_size). So we sync
2113 * the file data here, to try to honour O_DIRECT expectations.
2114 */
2115 if (unlikely(file->f_flags & O_DIRECT) && written)
2116 status = filemap_write_and_wait(mapping);
2117
2118 pagevec_lru_add(&lru_pvec);
2119 return written ? written : status;
2120}
2121EXPORT_SYMBOL(generic_file_buffered_write);
2122
Adrian Bunk5ce78522005-09-10 00:26:28 -07002123static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2125 unsigned long nr_segs, loff_t *ppos)
2126{
2127 struct file *file = iocb->ki_filp;
2128 struct address_space * mapping = file->f_mapping;
2129 size_t ocount; /* original count */
2130 size_t count; /* after file limit checks */
2131 struct inode *inode = mapping->host;
2132 unsigned long seg;
2133 loff_t pos;
2134 ssize_t written;
2135 ssize_t err;
2136
2137 ocount = 0;
2138 for (seg = 0; seg < nr_segs; seg++) {
2139 const struct iovec *iv = &iov[seg];
2140
2141 /*
2142 * If any segment has a negative length, or the cumulative
2143 * length ever wraps negative then return -EINVAL.
2144 */
2145 ocount += iv->iov_len;
2146 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2147 return -EINVAL;
2148 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2149 continue;
2150 if (seg == 0)
2151 return -EFAULT;
2152 nr_segs = seg;
2153 ocount -= iv->iov_len; /* This segment is no good */
2154 break;
2155 }
2156
2157 count = ocount;
2158 pos = *ppos;
2159
2160 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2161
2162 /* We can write back this queue in page reclaim */
2163 current->backing_dev_info = mapping->backing_dev_info;
2164 written = 0;
2165
2166 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2167 if (err)
2168 goto out;
2169
2170 if (count == 0)
2171 goto out;
2172
2173 err = remove_suid(file->f_dentry);
2174 if (err)
2175 goto out;
2176
Christoph Hellwig870f4812006-01-09 20:52:01 -08002177 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178
2179 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2180 if (unlikely(file->f_flags & O_DIRECT)) {
2181 written = generic_file_direct_write(iocb, iov,
2182 &nr_segs, pos, ppos, count, ocount);
2183 if (written < 0 || written == count)
2184 goto out;
2185 /*
2186 * direct-io write to a hole: fall through to buffered I/O
2187 * for completing the rest of the request.
2188 */
2189 pos += written;
2190 count -= written;
2191 }
2192
2193 written = generic_file_buffered_write(iocb, iov, nr_segs,
2194 pos, ppos, count, written);
2195out:
2196 current->backing_dev_info = NULL;
2197 return written ? written : err;
2198}
2199EXPORT_SYMBOL(generic_file_aio_write_nolock);
2200
2201ssize_t
2202generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2203 unsigned long nr_segs, loff_t *ppos)
2204{
2205 struct file *file = iocb->ki_filp;
2206 struct address_space *mapping = file->f_mapping;
2207 struct inode *inode = mapping->host;
2208 ssize_t ret;
2209 loff_t pos = *ppos;
2210
2211 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2212
2213 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2214 int err;
2215
2216 err = sync_page_range_nolock(inode, mapping, pos, ret);
2217 if (err < 0)
2218 ret = err;
2219 }
2220 return ret;
2221}
2222
Adrian Bunk5ce78522005-09-10 00:26:28 -07002223static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2225 unsigned long nr_segs, loff_t *ppos)
2226{
2227 struct kiocb kiocb;
2228 ssize_t ret;
2229
2230 init_sync_kiocb(&kiocb, file);
2231 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2232 if (ret == -EIOCBQUEUED)
2233 ret = wait_on_sync_kiocb(&kiocb);
2234 return ret;
2235}
2236
2237ssize_t
2238generic_file_write_nolock(struct file *file, 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, file);
2245 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2246 if (-EIOCBQUEUED == ret)
2247 ret = wait_on_sync_kiocb(&kiocb);
2248 return ret;
2249}
2250EXPORT_SYMBOL(generic_file_write_nolock);
2251
2252ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2253 size_t count, loff_t pos)
2254{
2255 struct file *file = iocb->ki_filp;
2256 struct address_space *mapping = file->f_mapping;
2257 struct inode *inode = mapping->host;
2258 ssize_t ret;
2259 struct iovec local_iov = { .iov_base = (void __user *)buf,
2260 .iov_len = count };
2261
2262 BUG_ON(iocb->ki_pos != pos);
2263
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002264 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002265 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2266 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002267 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268
2269 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2270 ssize_t err;
2271
2272 err = sync_page_range(inode, mapping, pos, ret);
2273 if (err < 0)
2274 ret = err;
2275 }
2276 return ret;
2277}
2278EXPORT_SYMBOL(generic_file_aio_write);
2279
2280ssize_t generic_file_write(struct file *file, const char __user *buf,
2281 size_t count, loff_t *ppos)
2282{
2283 struct address_space *mapping = file->f_mapping;
2284 struct inode *inode = mapping->host;
2285 ssize_t ret;
2286 struct iovec local_iov = { .iov_base = (void __user *)buf,
2287 .iov_len = count };
2288
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002289 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002290 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002291 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292
2293 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2294 ssize_t err;
2295
2296 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2297 if (err < 0)
2298 ret = err;
2299 }
2300 return ret;
2301}
2302EXPORT_SYMBOL(generic_file_write);
2303
2304ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2305 unsigned long nr_segs, loff_t *ppos)
2306{
2307 struct kiocb kiocb;
2308 ssize_t ret;
2309
2310 init_sync_kiocb(&kiocb, filp);
2311 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2312 if (-EIOCBQUEUED == ret)
2313 ret = wait_on_sync_kiocb(&kiocb);
2314 return ret;
2315}
2316EXPORT_SYMBOL(generic_file_readv);
2317
2318ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2319 unsigned long nr_segs, loff_t *ppos)
2320{
2321 struct address_space *mapping = file->f_mapping;
2322 struct inode *inode = mapping->host;
2323 ssize_t ret;
2324
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002325 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002327 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328
2329 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2330 int err;
2331
2332 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2333 if (err < 0)
2334 ret = err;
2335 }
2336 return ret;
2337}
2338EXPORT_SYMBOL(generic_file_writev);
2339
2340/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002341 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342 * went wrong during pagecache shootdown.
2343 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002344static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2346 loff_t offset, unsigned long nr_segs)
2347{
2348 struct file *file = iocb->ki_filp;
2349 struct address_space *mapping = file->f_mapping;
2350 ssize_t retval;
2351 size_t write_len = 0;
2352
2353 /*
2354 * If it's a write, unmap all mmappings of the file up-front. This
2355 * will cause any pte dirty bits to be propagated into the pageframes
2356 * for the subsequent filemap_write_and_wait().
2357 */
2358 if (rw == WRITE) {
2359 write_len = iov_length(iov, nr_segs);
2360 if (mapping_mapped(mapping))
2361 unmap_mapping_range(mapping, offset, write_len, 0);
2362 }
2363
2364 retval = filemap_write_and_wait(mapping);
2365 if (retval == 0) {
2366 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2367 offset, nr_segs);
2368 if (rw == WRITE && mapping->nrpages) {
2369 pgoff_t end = (offset + write_len - 1)
2370 >> PAGE_CACHE_SHIFT;
2371 int err = invalidate_inode_pages2_range(mapping,
2372 offset >> PAGE_CACHE_SHIFT, end);
2373 if (err)
2374 retval = err;
2375 }
2376 }
2377 return retval;
2378}