blob: 5209e47b7fe39dba855e84ee9ca4d89283fd3d80 [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 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/compiler.h>
15#include <linux/fs.h>
Hiro Yoshiokac22ce142006-06-23 02:04:16 -070016#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#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>
Linus Torvalds53253382007-10-18 14:47:32 -070028#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/pagevec.h>
30#include <linux/blkdev.h>
31#include <linux/security.h>
32#include <linux/syscalls.h>
Paul Jackson44110fe2006-03-24 03:16:04 -080033#include <linux/cpuset.h>
Nick Piggin2f718ff2007-10-16 01:24:59 -070034#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
Nick Piggin0f8053a2006-03-22 00:08:33 -080035#include "internal.h"
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 * FIXME: remove all knowledge of the buffer layer from the core VM
39 */
40#include <linux/buffer_head.h> /* for generic_osync_inode */
41
Linus Torvalds1da177e2005-04-16 15:20:36 -070042#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
Nick Piggin7a405072007-10-16 23:26:02 -070067 * ->zone.lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080069 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 * ->i_mmap_lock (truncate->unmap_mapping_range)
71 *
72 * ->mmap_sem
73 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070074 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
76 *
77 * ->mmap_sem
78 * ->lock_page (access_process_vm)
79 *
Nick Piggin82591e62006-10-19 23:29:10 -070080 * ->i_mutex (generic_file_buffered_write)
81 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080083 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 * ->i_alloc_sem (various)
85 *
86 * ->inode_lock
87 * ->sb_lock (fs/fs-writeback.c)
88 * ->mapping->tree_lock (__sync_single_inode)
89 *
90 * ->i_mmap_lock
91 * ->anon_vma.lock (vma_adjust)
92 *
93 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070094 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070096 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070097 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 * ->private_lock (try_to_unmap_one)
99 * ->tree_lock (try_to_unmap_one)
100 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -0800101 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 * ->private_lock (page_remove_rmap->set_page_dirty)
103 * ->tree_lock (page_remove_rmap->set_page_dirty)
104 * ->inode_lock (page_remove_rmap->set_page_dirty)
105 * ->inode_lock (zap_pte_range->set_page_dirty)
106 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
107 *
108 * ->task->proc_lock
109 * ->dcache_lock (proc_pid_lookup)
110 */
111
112/*
113 * Remove a page from the page cache and free it. Caller has to make
114 * sure the page is locked and that nobody else uses it - or that usage
115 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
116 */
117void __remove_from_page_cache(struct page *page)
118{
119 struct address_space *mapping = page->mapping;
120
121 radix_tree_delete(&mapping->page_tree, page->index);
122 page->mapping = NULL;
123 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700124 __dec_zone_page_state(page, NR_FILE_PAGES);
Nick Piggin45426812007-07-15 23:38:12 -0700125 BUG_ON(page_mapped(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126}
127
128void remove_from_page_cache(struct page *page)
129{
130 struct address_space *mapping = page->mapping;
131
Matt Mackallcd7619d2005-05-01 08:59:01 -0700132 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
134 write_lock_irq(&mapping->tree_lock);
135 __remove_from_page_cache(page);
136 write_unlock_irq(&mapping->tree_lock);
137}
138
139static int sync_page(void *word)
140{
141 struct address_space *mapping;
142 struct page *page;
143
Andi Kleen07808b72005-11-05 17:25:53 +0100144 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
146 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700147 * page_mapping() is being called without PG_locked held.
148 * Some knowledge of the state and use of the page is used to
149 * reduce the requirements down to a memory barrier.
150 * The danger here is of a stale page_mapping() return value
151 * indicating a struct address_space different from the one it's
152 * associated with when it is associated with one.
153 * After smp_mb(), it's either the correct page_mapping() for
154 * the page, or an old page_mapping() and the page's own
155 * page_mapping() has gone NULL.
156 * The ->sync_page() address_space operation must tolerate
157 * page_mapping() going NULL. By an amazing coincidence,
158 * this comes about because none of the users of the page
159 * in the ->sync_page() methods make essential use of the
160 * page_mapping(), merely passing the page down to the backing
161 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700162 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700163 * of interest. When page_mapping() does go NULL, the entire
164 * call stack gracefully ignores the page and returns.
165 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 */
167 smp_mb();
168 mapping = page_mapping(page);
169 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
170 mapping->a_ops->sync_page(page);
171 io_schedule();
172 return 0;
173}
174
175/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700176 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700177 * @mapping: address space structure to write
178 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800179 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700180 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700182 * Start writeback against all of a mapping's dirty pages that lie
183 * within the byte offsets <start, end> inclusive.
184 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700186 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 * these two operations is that if a dirty page/buffer is encountered, it must
188 * be waited upon, and not just skipped over.
189 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800190int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
191 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192{
193 int ret;
194 struct writeback_control wbc = {
195 .sync_mode = sync_mode,
196 .nr_to_write = mapping->nrpages * 2,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700197 .range_start = start,
198 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 };
200
201 if (!mapping_cap_writeback_dirty(mapping))
202 return 0;
203
204 ret = do_writepages(mapping, &wbc);
205 return ret;
206}
207
208static inline int __filemap_fdatawrite(struct address_space *mapping,
209 int sync_mode)
210{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700211 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212}
213
214int filemap_fdatawrite(struct address_space *mapping)
215{
216 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
217}
218EXPORT_SYMBOL(filemap_fdatawrite);
219
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800220static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
221 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222{
223 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
224}
225
Randy Dunlap485bb992006-06-23 02:03:49 -0700226/**
227 * filemap_flush - mostly a non-blocking flush
228 * @mapping: target address_space
229 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 * This is a mostly non-blocking flush. Not suitable for data-integrity
231 * purposes - I/O may not be started against all dirty pages.
232 */
233int filemap_flush(struct address_space *mapping)
234{
235 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
236}
237EXPORT_SYMBOL(filemap_flush);
238
Randy Dunlap485bb992006-06-23 02:03:49 -0700239/**
240 * wait_on_page_writeback_range - wait for writeback to complete
241 * @mapping: target address_space
242 * @start: beginning page index
243 * @end: ending page index
244 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 * Wait for writeback to complete against pages indexed by start->end
246 * inclusive
247 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800248int wait_on_page_writeback_range(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 pgoff_t start, pgoff_t end)
250{
251 struct pagevec pvec;
252 int nr_pages;
253 int ret = 0;
254 pgoff_t index;
255
256 if (end < start)
257 return 0;
258
259 pagevec_init(&pvec, 0);
260 index = start;
261 while ((index <= end) &&
262 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
263 PAGECACHE_TAG_WRITEBACK,
264 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
265 unsigned i;
266
267 for (i = 0; i < nr_pages; i++) {
268 struct page *page = pvec.pages[i];
269
270 /* until radix tree lookup accepts end_index */
271 if (page->index > end)
272 continue;
273
274 wait_on_page_writeback(page);
275 if (PageError(page))
276 ret = -EIO;
277 }
278 pagevec_release(&pvec);
279 cond_resched();
280 }
281
282 /* Check for outstanding write errors */
283 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
284 ret = -ENOSPC;
285 if (test_and_clear_bit(AS_EIO, &mapping->flags))
286 ret = -EIO;
287
288 return ret;
289}
290
Randy Dunlap485bb992006-06-23 02:03:49 -0700291/**
292 * sync_page_range - write and wait on all pages in the passed range
293 * @inode: target inode
294 * @mapping: target address_space
295 * @pos: beginning offset in pages to write
296 * @count: number of bytes to write
297 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 * Write and wait upon all the pages in the passed range. This is a "data
299 * integrity" operation. It waits upon in-flight writeout before starting and
300 * waiting upon new writeout. If there was an IO error, return it.
301 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800302 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 * it is otherwise livelockable.
304 */
305int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800306 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307{
308 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
309 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
310 int ret;
311
312 if (!mapping_cap_writeback_dirty(mapping) || !count)
313 return 0;
314 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
315 if (ret == 0) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800316 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800318 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 }
320 if (ret == 0)
321 ret = wait_on_page_writeback_range(mapping, start, end);
322 return ret;
323}
324EXPORT_SYMBOL(sync_page_range);
325
Randy Dunlap485bb992006-06-23 02:03:49 -0700326/**
327 * sync_page_range_nolock
328 * @inode: target inode
329 * @mapping: target address_space
330 * @pos: beginning offset in pages to write
331 * @count: number of bytes to write
332 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800333 * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 * as it forces O_SYNC writers to different parts of the same file
335 * to be serialised right until io completion.
336 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800337int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
338 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339{
340 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
341 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
342 int ret;
343
344 if (!mapping_cap_writeback_dirty(mapping) || !count)
345 return 0;
346 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
347 if (ret == 0)
348 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
349 if (ret == 0)
350 ret = wait_on_page_writeback_range(mapping, start, end);
351 return ret;
352}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800353EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
355/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700356 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700358 *
359 * Walk the list of under-writeback pages of the given address space
360 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 */
362int filemap_fdatawait(struct address_space *mapping)
363{
364 loff_t i_size = i_size_read(mapping->host);
365
366 if (i_size == 0)
367 return 0;
368
369 return wait_on_page_writeback_range(mapping, 0,
370 (i_size - 1) >> PAGE_CACHE_SHIFT);
371}
372EXPORT_SYMBOL(filemap_fdatawait);
373
374int filemap_write_and_wait(struct address_space *mapping)
375{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800376 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377
378 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800379 err = filemap_fdatawrite(mapping);
380 /*
381 * Even if the above returned error, the pages may be
382 * written partially (e.g. -ENOSPC), so we wait for it.
383 * But the -EIO is special case, it may indicate the worst
384 * thing (e.g. bug) happened, so we avoid waiting for it.
385 */
386 if (err != -EIO) {
387 int err2 = filemap_fdatawait(mapping);
388 if (!err)
389 err = err2;
390 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800392 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800394EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395
Randy Dunlap485bb992006-06-23 02:03:49 -0700396/**
397 * filemap_write_and_wait_range - write out & wait on a file range
398 * @mapping: the address_space for the pages
399 * @lstart: offset in bytes where the range starts
400 * @lend: offset in bytes where the range ends (inclusive)
401 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800402 * Write out and wait upon file offsets lstart->lend, inclusive.
403 *
404 * Note that `lend' is inclusive (describes the last byte to be written) so
405 * that this function can be used to write to the very end-of-file (end = -1).
406 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407int filemap_write_and_wait_range(struct address_space *mapping,
408 loff_t lstart, loff_t lend)
409{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800410 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411
412 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800413 err = __filemap_fdatawrite_range(mapping, lstart, lend,
414 WB_SYNC_ALL);
415 /* See comment of filemap_write_and_wait() */
416 if (err != -EIO) {
417 int err2 = wait_on_page_writeback_range(mapping,
418 lstart >> PAGE_CACHE_SHIFT,
419 lend >> PAGE_CACHE_SHIFT);
420 if (!err)
421 err = err2;
422 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800424 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700425}
426
Randy Dunlap485bb992006-06-23 02:03:49 -0700427/**
428 * add_to_page_cache - add newly allocated pagecache pages
429 * @page: page to add
430 * @mapping: the page's address_space
431 * @offset: page index
432 * @gfp_mask: page allocation mode
433 *
434 * This function is used to add newly allocated pagecache pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 * the page is new, so we can just run SetPageLocked() against it.
436 * The other page state flags were set by rmqueue().
437 *
438 * This function does not add the page to the LRU. The caller must do that.
439 */
440int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400441 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442{
443 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
444
445 if (error == 0) {
446 write_lock_irq(&mapping->tree_lock);
447 error = radix_tree_insert(&mapping->page_tree, offset, page);
448 if (!error) {
449 page_cache_get(page);
450 SetPageLocked(page);
451 page->mapping = mapping;
452 page->index = offset;
453 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700454 __inc_zone_page_state(page, NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 }
456 write_unlock_irq(&mapping->tree_lock);
457 radix_tree_preload_end();
458 }
459 return error;
460}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461EXPORT_SYMBOL(add_to_page_cache);
462
463int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400464 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465{
466 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
467 if (ret == 0)
468 lru_cache_add(page);
469 return ret;
470}
471
Paul Jackson44110fe2006-03-24 03:16:04 -0800472#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700473struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800474{
475 if (cpuset_do_page_mem_spread()) {
476 int n = cpuset_mem_spread_node();
Nick Piggin2ae88142006-10-28 10:38:23 -0700477 return alloc_pages_node(n, gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800478 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700479 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800480}
Nick Piggin2ae88142006-10-28 10:38:23 -0700481EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800482#endif
483
Nick Piggindb376482006-09-25 23:31:24 -0700484static int __sleep_on_page_lock(void *word)
485{
486 io_schedule();
487 return 0;
488}
489
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490/*
491 * In order to wait for pages to become available there must be
492 * waitqueues associated with pages. By using a hash table of
493 * waitqueues where the bucket discipline is to maintain all
494 * waiters on the same queue and wake all when any of the pages
495 * become available, and for the woken contexts to check to be
496 * sure the appropriate page became available, this saves space
497 * at a cost of "thundering herd" phenomena during rare hash
498 * collisions.
499 */
500static wait_queue_head_t *page_waitqueue(struct page *page)
501{
502 const struct zone *zone = page_zone(page);
503
504 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
505}
506
507static inline void wake_up_page(struct page *page, int bit)
508{
509 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
510}
511
512void fastcall wait_on_page_bit(struct page *page, int bit_nr)
513{
514 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
515
516 if (test_bit(bit_nr, &page->flags))
517 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
518 TASK_UNINTERRUPTIBLE);
519}
520EXPORT_SYMBOL(wait_on_page_bit);
521
522/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700523 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524 * @page: the page
525 *
526 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
527 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
528 * mechananism between PageLocked pages and PageWriteback pages is shared.
529 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
530 *
531 * The first mb is necessary to safely close the critical section opened by the
532 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
533 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
534 * parallel wait_on_page_locked()).
535 */
536void fastcall unlock_page(struct page *page)
537{
538 smp_mb__before_clear_bit();
539 if (!TestClearPageLocked(page))
540 BUG();
541 smp_mb__after_clear_bit();
542 wake_up_page(page, PG_locked);
543}
544EXPORT_SYMBOL(unlock_page);
545
Randy Dunlap485bb992006-06-23 02:03:49 -0700546/**
547 * end_page_writeback - end writeback against a page
548 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 */
550void end_page_writeback(struct page *page)
551{
552 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
553 if (!test_clear_page_writeback(page))
554 BUG();
555 }
556 smp_mb__after_clear_bit();
557 wake_up_page(page, PG_writeback);
558}
559EXPORT_SYMBOL(end_page_writeback);
560
Randy Dunlap485bb992006-06-23 02:03:49 -0700561/**
562 * __lock_page - get a lock on the page, assuming we need to sleep to get it
563 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700565 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
567 * chances are that on the second loop, the block layer's plug list is empty,
568 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
569 */
570void fastcall __lock_page(struct page *page)
571{
572 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
573
574 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
575 TASK_UNINTERRUPTIBLE);
576}
577EXPORT_SYMBOL(__lock_page);
578
Nick Piggindb376482006-09-25 23:31:24 -0700579/*
580 * Variant of lock_page that does not require the caller to hold a reference
581 * on the page's mapping.
582 */
583void fastcall __lock_page_nosync(struct page *page)
584{
585 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
586 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
587 TASK_UNINTERRUPTIBLE);
588}
589
Randy Dunlap485bb992006-06-23 02:03:49 -0700590/**
591 * find_get_page - find and get a page reference
592 * @mapping: the address_space to search
593 * @offset: the page index
594 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700595 * Is there a pagecache struct page at the given (mapping, offset) tuple?
596 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 */
Fengguang Wu57f6b962007-10-16 01:24:37 -0700598struct page * find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599{
600 struct page *page;
601
602 read_lock_irq(&mapping->tree_lock);
603 page = radix_tree_lookup(&mapping->page_tree, offset);
604 if (page)
605 page_cache_get(page);
606 read_unlock_irq(&mapping->tree_lock);
607 return page;
608}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609EXPORT_SYMBOL(find_get_page);
610
Randy Dunlap485bb992006-06-23 02:03:49 -0700611/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700613 * @mapping: the address_space to search
614 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 *
616 * Locates the desired pagecache page, locks it, increments its reference
617 * count and returns its address.
618 *
619 * Returns zero if the page was not present. find_lock_page() may sleep.
620 */
621struct page *find_lock_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700622 pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623{
624 struct page *page;
625
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626repeat:
Nick Piggin45726cb2007-10-16 01:24:41 -0700627 read_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 page = radix_tree_lookup(&mapping->page_tree, offset);
629 if (page) {
630 page_cache_get(page);
631 if (TestSetPageLocked(page)) {
632 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800633 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634
635 /* Has the page been truncated while we slept? */
Nick Piggin45726cb2007-10-16 01:24:41 -0700636 if (unlikely(page->mapping != mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 unlock_page(page);
638 page_cache_release(page);
639 goto repeat;
640 }
Nick Piggin45726cb2007-10-16 01:24:41 -0700641 VM_BUG_ON(page->index != offset);
642 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 }
644 }
645 read_unlock_irq(&mapping->tree_lock);
Nick Piggin45726cb2007-10-16 01:24:41 -0700646out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 return page;
648}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700649EXPORT_SYMBOL(find_lock_page);
650
651/**
652 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700653 * @mapping: the page's address_space
654 * @index: the page's index into the mapping
655 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 *
657 * Locates a page in the pagecache. If the page is not present, a new page
658 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
659 * LRU list. The returned page is locked and has its reference count
660 * incremented.
661 *
662 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
663 * allocation!
664 *
665 * find_or_create_page() returns the desired page's address, or zero on
666 * memory exhaustion.
667 */
668struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700669 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670{
Nick Piggineb2be182007-10-16 01:24:57 -0700671 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 int err;
673repeat:
674 page = find_lock_page(mapping, index);
675 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700676 page = __page_cache_alloc(gfp_mask);
677 if (!page)
678 return NULL;
679 err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
680 if (unlikely(err)) {
681 page_cache_release(page);
682 page = NULL;
683 if (err == -EEXIST)
684 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 return page;
688}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689EXPORT_SYMBOL(find_or_create_page);
690
691/**
692 * find_get_pages - gang pagecache lookup
693 * @mapping: The address_space to search
694 * @start: The starting page index
695 * @nr_pages: The maximum number of pages
696 * @pages: Where the resulting pages are placed
697 *
698 * find_get_pages() will search for and return a group of up to
699 * @nr_pages pages in the mapping. The pages are placed at @pages.
700 * find_get_pages() takes a reference against the returned pages.
701 *
702 * The search returns a group of mapping-contiguous pages with ascending
703 * indexes. There may be holes in the indices due to not-present pages.
704 *
705 * find_get_pages() returns the number of pages which were found.
706 */
707unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
708 unsigned int nr_pages, struct page **pages)
709{
710 unsigned int i;
711 unsigned int ret;
712
713 read_lock_irq(&mapping->tree_lock);
714 ret = radix_tree_gang_lookup(&mapping->page_tree,
715 (void **)pages, start, nr_pages);
716 for (i = 0; i < ret; i++)
717 page_cache_get(pages[i]);
718 read_unlock_irq(&mapping->tree_lock);
719 return ret;
720}
721
Jens Axboeebf43502006-04-27 08:46:01 +0200722/**
723 * find_get_pages_contig - gang contiguous pagecache lookup
724 * @mapping: The address_space to search
725 * @index: The starting page index
726 * @nr_pages: The maximum number of pages
727 * @pages: Where the resulting pages are placed
728 *
729 * find_get_pages_contig() works exactly like find_get_pages(), except
730 * that the returned number of pages are guaranteed to be contiguous.
731 *
732 * find_get_pages_contig() returns the number of pages which were found.
733 */
734unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
735 unsigned int nr_pages, struct page **pages)
736{
737 unsigned int i;
738 unsigned int ret;
739
740 read_lock_irq(&mapping->tree_lock);
741 ret = radix_tree_gang_lookup(&mapping->page_tree,
742 (void **)pages, index, nr_pages);
743 for (i = 0; i < ret; i++) {
744 if (pages[i]->mapping == NULL || pages[i]->index != index)
745 break;
746
747 page_cache_get(pages[i]);
748 index++;
749 }
750 read_unlock_irq(&mapping->tree_lock);
751 return i;
752}
David Howellsef71c152007-05-09 02:33:44 -0700753EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200754
Randy Dunlap485bb992006-06-23 02:03:49 -0700755/**
756 * find_get_pages_tag - find and return pages that match @tag
757 * @mapping: the address_space to search
758 * @index: the starting page index
759 * @tag: the tag index
760 * @nr_pages: the maximum number of pages
761 * @pages: where the resulting pages are placed
762 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700764 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 */
766unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
767 int tag, unsigned int nr_pages, struct page **pages)
768{
769 unsigned int i;
770 unsigned int ret;
771
772 read_lock_irq(&mapping->tree_lock);
773 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
774 (void **)pages, *index, nr_pages, tag);
775 for (i = 0; i < ret; i++)
776 page_cache_get(pages[i]);
777 if (ret)
778 *index = pages[ret - 1]->index + 1;
779 read_unlock_irq(&mapping->tree_lock);
780 return ret;
781}
David Howellsef71c152007-05-09 02:33:44 -0700782EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783
Randy Dunlap485bb992006-06-23 02:03:49 -0700784/**
785 * grab_cache_page_nowait - returns locked page at given index in given cache
786 * @mapping: target address_space
787 * @index: the page index
788 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800789 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 * This is intended for speculative data generators, where the data can
791 * be regenerated if the page couldn't be grabbed. This routine should
792 * be safe to call while holding the lock for another page.
793 *
794 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
795 * and deadlock against the caller's locked page.
796 */
797struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700798grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799{
800 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801
802 if (page) {
803 if (!TestSetPageLocked(page))
804 return page;
805 page_cache_release(page);
806 return NULL;
807 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700808 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
809 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 page_cache_release(page);
811 page = NULL;
812 }
813 return page;
814}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815EXPORT_SYMBOL(grab_cache_page_nowait);
816
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700817/*
818 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
819 * a _large_ part of the i/o request. Imagine the worst scenario:
820 *
821 * ---R__________________________________________B__________
822 * ^ reading here ^ bad block(assume 4k)
823 *
824 * read(R) => miss => readahead(R...B) => media error => frustrating retries
825 * => failing the whole request => read(R) => read(R+1) =>
826 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
827 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
828 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
829 *
830 * It is going insane. Fix it by quickly scaling down the readahead size.
831 */
832static void shrink_readahead_size_eio(struct file *filp,
833 struct file_ra_state *ra)
834{
835 if (!ra->ra_pages)
836 return;
837
838 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700839}
840
Randy Dunlap485bb992006-06-23 02:03:49 -0700841/**
842 * do_generic_mapping_read - generic file read routine
843 * @mapping: address_space to be read
Randy Dunlap8f731f72007-10-18 23:39:28 -0700844 * @ra: file's readahead state
Randy Dunlap485bb992006-06-23 02:03:49 -0700845 * @filp: the file to read
846 * @ppos: current file position
847 * @desc: read_descriptor
848 * @actor: read method
849 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700851 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852 *
853 * This is really ugly. But the goto's actually try to clarify some
854 * of the logic when it comes to error handling etc.
855 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700856 * Note the struct file* is only passed for the use of readpage.
857 * It may be NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 */
859void do_generic_mapping_read(struct address_space *mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -0700860 struct file_ra_state *ra,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 struct file *filp,
862 loff_t *ppos,
863 read_descriptor_t *desc,
864 read_actor_t actor)
865{
866 struct inode *inode = mapping->host;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700867 pgoff_t index;
868 pgoff_t last_index;
869 pgoff_t prev_index;
870 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -0700871 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -0700875 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
876 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
878 offset = *ppos & ~PAGE_CACHE_MASK;
879
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 for (;;) {
881 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700882 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -0700883 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 unsigned long nr, ret;
885
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887find_page:
888 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700889 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -0700890 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -0700891 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700892 index, last_index - index);
893 page = find_get_page(mapping, index);
894 if (unlikely(page == NULL))
895 goto no_cached_page;
896 }
897 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -0700898 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -0700899 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700900 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 }
902 if (!PageUptodate(page))
903 goto page_not_up_to_date;
904page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -0700905 /*
906 * i_size must be checked after we know the page is Uptodate.
907 *
908 * Checking i_size after the check allows us to calculate
909 * the correct value for "nr", which means the zero-filled
910 * part of the page is not copied back to userspace (unless
911 * another truncate extends the file - this is desired though).
912 */
913
914 isize = i_size_read(inode);
915 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
916 if (unlikely(!isize || index > end_index)) {
917 page_cache_release(page);
918 goto out;
919 }
920
921 /* nr is the maximum number of bytes to copy from this page */
922 nr = PAGE_CACHE_SIZE;
923 if (index == end_index) {
924 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
925 if (nr <= offset) {
926 page_cache_release(page);
927 goto out;
928 }
929 }
930 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931
932 /* If users can be writing to this page using arbitrary
933 * virtual addresses, take care about potential aliasing
934 * before reading the page on the kernel side.
935 */
936 if (mapping_writably_mapped(mapping))
937 flush_dcache_page(page);
938
939 /*
Jan Karaec0f1632007-05-06 14:49:25 -0700940 * When a sequential read accesses a page several times,
941 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700942 */
Jan Karaec0f1632007-05-06 14:49:25 -0700943 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700944 mark_page_accessed(page);
945 prev_index = index;
946
947 /*
948 * Ok, we have the page, and it's up-to-date, so
949 * now we can copy it to user space...
950 *
951 * The actor routine returns how many bytes were actually used..
952 * NOTE! This may not be the same as how much of a user buffer
953 * we filled up (we may be padding etc), so we can only update
954 * "pos" here (the actor routine has to update the user buffer
955 * pointers and the remaining count).
956 */
957 ret = actor(desc, page, offset, nr);
958 offset += ret;
959 index += offset >> PAGE_CACHE_SHIFT;
960 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -0700961 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962
963 page_cache_release(page);
964 if (ret == nr && desc->count)
965 continue;
966 goto out;
967
968page_not_up_to_date:
969 /* Get exclusive access to the page ... */
970 lock_page(page);
971
Nick Pigginda6052f2006-09-25 23:31:35 -0700972 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 if (!page->mapping) {
974 unlock_page(page);
975 page_cache_release(page);
976 continue;
977 }
978
979 /* Did somebody else fill it already? */
980 if (PageUptodate(page)) {
981 unlock_page(page);
982 goto page_ok;
983 }
984
985readpage:
986 /* Start the actual read. The read will unlock the page. */
987 error = mapping->a_ops->readpage(filp, page);
988
Zach Brown994fc28c2005-12-15 14:28:17 -0800989 if (unlikely(error)) {
990 if (error == AOP_TRUNCATED_PAGE) {
991 page_cache_release(page);
992 goto find_page;
993 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800995 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996
997 if (!PageUptodate(page)) {
998 lock_page(page);
999 if (!PageUptodate(page)) {
1000 if (page->mapping == NULL) {
1001 /*
1002 * invalidate_inode_pages got it
1003 */
1004 unlock_page(page);
1005 page_cache_release(page);
1006 goto find_page;
1007 }
1008 unlock_page(page);
1009 error = -EIO;
Fengguang Wu7ff81072007-10-16 01:24:35 -07001010 shrink_readahead_size_eio(filp, ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 goto readpage_error;
1012 }
1013 unlock_page(page);
1014 }
1015
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016 goto page_ok;
1017
1018readpage_error:
1019 /* UHHUH! A synchronous read error occurred. Report it */
1020 desc->error = error;
1021 page_cache_release(page);
1022 goto out;
1023
1024no_cached_page:
1025 /*
1026 * Ok, it wasn't cached, so we need to create a new
1027 * page..
1028 */
Nick Piggineb2be182007-10-16 01:24:57 -07001029 page = page_cache_alloc_cold(mapping);
1030 if (!page) {
1031 desc->error = -ENOMEM;
1032 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 }
Nick Piggineb2be182007-10-16 01:24:57 -07001034 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035 index, GFP_KERNEL);
1036 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001037 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 if (error == -EEXIST)
1039 goto find_page;
1040 desc->error = error;
1041 goto out;
1042 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 goto readpage;
1044 }
1045
1046out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001047 ra->prev_pos = prev_index;
1048 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1049 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001051 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 if (filp)
1053 file_accessed(filp);
1054}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055EXPORT_SYMBOL(do_generic_mapping_read);
1056
1057int file_read_actor(read_descriptor_t *desc, struct page *page,
1058 unsigned long offset, unsigned long size)
1059{
1060 char *kaddr;
1061 unsigned long left, count = desc->count;
1062
1063 if (size > count)
1064 size = count;
1065
1066 /*
1067 * Faults on the destination of a read are common, so do it before
1068 * taking the kmap.
1069 */
1070 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1071 kaddr = kmap_atomic(page, KM_USER0);
1072 left = __copy_to_user_inatomic(desc->arg.buf,
1073 kaddr + offset, size);
1074 kunmap_atomic(kaddr, KM_USER0);
1075 if (left == 0)
1076 goto success;
1077 }
1078
1079 /* Do it the slow way */
1080 kaddr = kmap(page);
1081 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1082 kunmap(page);
1083
1084 if (left) {
1085 size -= left;
1086 desc->error = -EFAULT;
1087 }
1088success:
1089 desc->count = count - size;
1090 desc->written += size;
1091 desc->arg.buf += size;
1092 return size;
1093}
1094
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001095/*
1096 * Performs necessary checks before doing a write
1097 * @iov: io vector request
1098 * @nr_segs: number of segments in the iovec
1099 * @count: number of bytes to write
1100 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1101 *
1102 * Adjust number of segments and amount of bytes to write (nr_segs should be
1103 * properly initialized first). Returns appropriate error code that caller
1104 * should return or zero in case that write should be allowed.
1105 */
1106int generic_segment_checks(const struct iovec *iov,
1107 unsigned long *nr_segs, size_t *count, int access_flags)
1108{
1109 unsigned long seg;
1110 size_t cnt = 0;
1111 for (seg = 0; seg < *nr_segs; seg++) {
1112 const struct iovec *iv = &iov[seg];
1113
1114 /*
1115 * If any segment has a negative length, or the cumulative
1116 * length ever wraps negative then return -EINVAL.
1117 */
1118 cnt += iv->iov_len;
1119 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1120 return -EINVAL;
1121 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1122 continue;
1123 if (seg == 0)
1124 return -EFAULT;
1125 *nr_segs = seg;
1126 cnt -= iv->iov_len; /* This segment is no good */
1127 break;
1128 }
1129 *count = cnt;
1130 return 0;
1131}
1132EXPORT_SYMBOL(generic_segment_checks);
1133
Randy Dunlap485bb992006-06-23 02:03:49 -07001134/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001135 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001136 * @iocb: kernel I/O control block
1137 * @iov: io vector request
1138 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001139 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001140 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 * This is the "read()" routine for all filesystems
1142 * that can use the page cache directly.
1143 */
1144ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001145generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1146 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147{
1148 struct file *filp = iocb->ki_filp;
1149 ssize_t retval;
1150 unsigned long seg;
1151 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001152 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153
1154 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001155 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1156 if (retval)
1157 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158
1159 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1160 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001161 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 struct address_space *mapping;
1163 struct inode *inode;
1164
1165 mapping = filp->f_mapping;
1166 inode = mapping->host;
1167 retval = 0;
1168 if (!count)
1169 goto out; /* skip atime */
1170 size = i_size_read(inode);
1171 if (pos < size) {
1172 retval = generic_file_direct_IO(READ, iocb,
1173 iov, pos, nr_segs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 if (retval > 0)
1175 *ppos = pos + retval;
1176 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001177 if (likely(retval != 0)) {
Steven Whitehouse3f1a9aa2006-09-27 14:52:48 -04001178 file_accessed(filp);
Steven Whitehousea9e5f4d2006-07-25 17:24:12 -04001179 goto out;
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001180 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 }
1182
1183 retval = 0;
1184 if (count) {
1185 for (seg = 0; seg < nr_segs; seg++) {
1186 read_descriptor_t desc;
1187
1188 desc.written = 0;
1189 desc.arg.buf = iov[seg].iov_base;
1190 desc.count = iov[seg].iov_len;
1191 if (desc.count == 0)
1192 continue;
1193 desc.error = 0;
1194 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1195 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001196 if (desc.error) {
1197 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 break;
1199 }
akpm@linux-foundation.orgc44939e2007-07-15 23:38:25 -07001200 if (desc.count > 0)
1201 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202 }
1203 }
1204out:
1205 return retval;
1206}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207EXPORT_SYMBOL(generic_file_aio_read);
1208
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209static ssize_t
1210do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001211 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212{
1213 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1214 return -EINVAL;
1215
1216 force_page_cache_readahead(mapping, filp, index,
1217 max_sane_readahead(nr));
1218 return 0;
1219}
1220
1221asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1222{
1223 ssize_t ret;
1224 struct file *file;
1225
1226 ret = -EBADF;
1227 file = fget(fd);
1228 if (file) {
1229 if (file->f_mode & FMODE_READ) {
1230 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001231 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1232 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 unsigned long len = end - start + 1;
1234 ret = do_readahead(mapping, file, start, len);
1235 }
1236 fput(file);
1237 }
1238 return ret;
1239}
1240
1241#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001242/**
1243 * page_cache_read - adds requested page to the page cache if not already there
1244 * @file: file to read
1245 * @offset: page index
1246 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247 * This adds the requested page to the page cache if it isn't already there,
1248 * and schedules an I/O to read in its contents from disk.
1249 */
Fengguang Wu57f6b962007-10-16 01:24:37 -07001250static int fastcall page_cache_read(struct file * file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251{
1252 struct address_space *mapping = file->f_mapping;
1253 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001254 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001255
Zach Brown994fc28c2005-12-15 14:28:17 -08001256 do {
1257 page = page_cache_alloc_cold(mapping);
1258 if (!page)
1259 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260
Zach Brown994fc28c2005-12-15 14:28:17 -08001261 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1262 if (ret == 0)
1263 ret = mapping->a_ops->readpage(file, page);
1264 else if (ret == -EEXIST)
1265 ret = 0; /* losing race to add is OK */
1266
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268
Zach Brown994fc28c2005-12-15 14:28:17 -08001269 } while (ret == AOP_TRUNCATED_PAGE);
1270
1271 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272}
1273
1274#define MMAP_LOTSAMISS (100)
1275
Randy Dunlap485bb992006-06-23 02:03:49 -07001276/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001277 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001278 * @vma: vma in which the fault was taken
1279 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001280 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001281 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 * mapped memory region to read in file data during a page fault.
1283 *
1284 * The goto's are kind of ugly, but this streamlines the normal case of having
1285 * it in the page cache, and handles the special cases reasonably without
1286 * having a lot of duplicated code.
1287 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001288int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289{
1290 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001291 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292 struct address_space *mapping = file->f_mapping;
1293 struct file_ra_state *ra = &file->f_ra;
1294 struct inode *inode = mapping->host;
1295 struct page *page;
Nick Piggin54cb8822007-07-19 01:46:59 -07001296 unsigned long size;
1297 int did_readaround = 0;
Nick Piggin83c54072007-07-19 01:47:05 -07001298 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001301 if (vmf->pgoff >= size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302 goto outside_data_content;
1303
1304 /* If we don't want any read-ahead, don't bother */
Nick Piggin54cb8822007-07-19 01:46:59 -07001305 if (VM_RandomReadHint(vma))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306 goto no_cached_page;
1307
1308 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 * Do we have something in the page cache already?
1310 */
1311retry_find:
Nick Piggind0217ac2007-07-19 01:47:03 -07001312 page = find_lock_page(mapping, vmf->pgoff);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001313 /*
1314 * For sequential accesses, we use the generic readahead logic.
1315 */
1316 if (VM_SequentialReadHint(vma)) {
1317 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001318 page_cache_sync_readahead(mapping, ra, file,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001319 vmf->pgoff, 1);
1320 page = find_lock_page(mapping, vmf->pgoff);
1321 if (!page)
1322 goto no_cached_page;
1323 }
1324 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001325 page_cache_async_readahead(mapping, ra, file, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001326 vmf->pgoff, 1);
1327 }
1328 }
1329
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330 if (!page) {
1331 unsigned long ra_pages;
1332
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 ra->mmap_miss++;
1334
1335 /*
1336 * Do we miss much more than hit in this file? If so,
1337 * stop bothering with read-ahead. It will only hurt.
1338 */
Fengguang Wu0bb7ba62007-10-16 01:24:32 -07001339 if (ra->mmap_miss > MMAP_LOTSAMISS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 goto no_cached_page;
1341
1342 /*
1343 * To keep the pgmajfault counter straight, we need to
1344 * check did_readaround, as this is an inner loop.
1345 */
1346 if (!did_readaround) {
Nick Piggind0217ac2007-07-19 01:47:03 -07001347 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001348 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 }
1350 did_readaround = 1;
1351 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1352 if (ra_pages) {
1353 pgoff_t start = 0;
1354
Nick Piggind0217ac2007-07-19 01:47:03 -07001355 if (vmf->pgoff > ra_pages / 2)
1356 start = vmf->pgoff - ra_pages / 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357 do_page_cache_readahead(mapping, file, start, ra_pages);
1358 }
Nick Piggind0217ac2007-07-19 01:47:03 -07001359 page = find_lock_page(mapping, vmf->pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 if (!page)
1361 goto no_cached_page;
1362 }
1363
1364 if (!did_readaround)
Fengguang Wu0bb7ba62007-10-16 01:24:32 -07001365 ra->mmap_miss--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366
1367 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001368 * We have a locked page in the page cache, now we need to check
1369 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 */
Nick Piggind00806b2007-07-19 01:46:57 -07001371 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 goto page_not_uptodate;
1373
Nick Piggind00806b2007-07-19 01:46:57 -07001374 /* Must recheck i_size under page lock */
1375 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001376 if (unlikely(vmf->pgoff >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001377 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001378 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001379 goto outside_data_content;
1380 }
1381
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 /*
1383 * Found the page and have a reference on it.
1384 */
1385 mark_page_accessed(page);
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001386 ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001387 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001388 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389
1390outside_data_content:
1391 /*
1392 * An external ptracer can access pages that normally aren't
1393 * accessible..
1394 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001395 if (vma->vm_mm == current->mm)
1396 return VM_FAULT_SIGBUS;
1397
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 /* Fall through to the non-read-ahead case */
1399no_cached_page:
1400 /*
1401 * We're only likely to ever get here if MADV_RANDOM is in
1402 * effect.
1403 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001404 error = page_cache_read(file, vmf->pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405
1406 /*
1407 * The page we want has now been added to the page cache.
1408 * In the unlikely event that someone removed it in the
1409 * meantime, we'll just come back here and read it again.
1410 */
1411 if (error >= 0)
1412 goto retry_find;
1413
1414 /*
1415 * An error return from page_cache_read can result if the
1416 * system is low on memory, or a problem occurs while trying
1417 * to schedule I/O.
1418 */
1419 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001420 return VM_FAULT_OOM;
1421 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422
1423page_not_uptodate:
Nick Piggind00806b2007-07-19 01:46:57 -07001424 /* IO error path */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 if (!did_readaround) {
Nick Piggind0217ac2007-07-19 01:47:03 -07001426 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001427 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429
1430 /*
1431 * Umm, take care of errors if the page isn't up-to-date.
1432 * Try to re-read it _once_. We do this synchronously,
1433 * because there really aren't any performance issues here
1434 * and we need to check for errors.
1435 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001437 error = mapping->a_ops->readpage(file, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001439
1440 if (!error || error == AOP_TRUNCATED_PAGE)
1441 goto retry_find;
1442
1443 /* Things didn't work out. Return zero to tell the mm layer so. */
1444 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001445 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001446}
1447EXPORT_SYMBOL(filemap_fault);
1448
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001450 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451};
1452
1453/* This is used for a general mmap of a disk file */
1454
1455int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1456{
1457 struct address_space *mapping = file->f_mapping;
1458
1459 if (!mapping->a_ops->readpage)
1460 return -ENOEXEC;
1461 file_accessed(file);
1462 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001463 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 return 0;
1465}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466
1467/*
1468 * This is for filesystems which do not implement ->writepage.
1469 */
1470int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1471{
1472 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1473 return -EINVAL;
1474 return generic_file_mmap(file, vma);
1475}
1476#else
1477int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1478{
1479 return -ENOSYS;
1480}
1481int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1482{
1483 return -ENOSYS;
1484}
1485#endif /* CONFIG_MMU */
1486
1487EXPORT_SYMBOL(generic_file_mmap);
1488EXPORT_SYMBOL(generic_file_readonly_mmap);
1489
Nick Piggin6fe69002007-05-06 14:49:04 -07001490static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001491 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 int (*filler)(void *,struct page*),
1493 void *data)
1494{
Nick Piggineb2be182007-10-16 01:24:57 -07001495 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 int err;
1497repeat:
1498 page = find_get_page(mapping, index);
1499 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -07001500 page = page_cache_alloc_cold(mapping);
1501 if (!page)
1502 return ERR_PTR(-ENOMEM);
1503 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1504 if (unlikely(err)) {
1505 page_cache_release(page);
1506 if (err == -EEXIST)
1507 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 return ERR_PTR(err);
1510 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511 err = filler(data, page);
1512 if (err < 0) {
1513 page_cache_release(page);
1514 page = ERR_PTR(err);
1515 }
1516 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 return page;
1518}
1519
Nick Piggin6fe69002007-05-06 14:49:04 -07001520/*
1521 * Same as read_cache_page, but don't wait for page to become unlocked
1522 * after submitting it to the filler.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 */
Nick Piggin6fe69002007-05-06 14:49:04 -07001524struct page *read_cache_page_async(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001525 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 int (*filler)(void *,struct page*),
1527 void *data)
1528{
1529 struct page *page;
1530 int err;
1531
1532retry:
1533 page = __read_cache_page(mapping, index, filler, data);
1534 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001535 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 if (PageUptodate(page))
1537 goto out;
1538
1539 lock_page(page);
1540 if (!page->mapping) {
1541 unlock_page(page);
1542 page_cache_release(page);
1543 goto retry;
1544 }
1545 if (PageUptodate(page)) {
1546 unlock_page(page);
1547 goto out;
1548 }
1549 err = filler(data, page);
1550 if (err < 0) {
1551 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001552 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 }
David Howellsc855ff32007-05-09 13:42:20 +01001554out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001555 mark_page_accessed(page);
1556 return page;
1557}
1558EXPORT_SYMBOL(read_cache_page_async);
1559
1560/**
1561 * read_cache_page - read into page cache, fill it if needed
1562 * @mapping: the page's address_space
1563 * @index: the page index
1564 * @filler: function to perform the read
1565 * @data: destination for read data
1566 *
1567 * Read into the page cache. If a page already exists, and PageUptodate() is
1568 * not set, try to fill the page then wait for it to become unlocked.
1569 *
1570 * If the page does not get brought uptodate, return -EIO.
1571 */
1572struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001573 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001574 int (*filler)(void *,struct page*),
1575 void *data)
1576{
1577 struct page *page;
1578
1579 page = read_cache_page_async(mapping, index, filler, data);
1580 if (IS_ERR(page))
1581 goto out;
1582 wait_on_page_locked(page);
1583 if (!PageUptodate(page)) {
1584 page_cache_release(page);
1585 page = ERR_PTR(-EIO);
1586 }
1587 out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588 return page;
1589}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590EXPORT_SYMBOL(read_cache_page);
1591
1592/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 * The logic we want is
1594 *
1595 * if suid or (sgid and xgrp)
1596 * remove privs
1597 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001598int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599{
1600 mode_t mode = dentry->d_inode->i_mode;
1601 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602
1603 /* suid always must be killed */
1604 if (unlikely(mode & S_ISUID))
1605 kill = ATTR_KILL_SUID;
1606
1607 /*
1608 * sgid without any exec bits is just a mandatory locking mark; leave
1609 * it alone. If some exec bits are set, it's a real sgid; kill it.
1610 */
1611 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1612 kill |= ATTR_KILL_SGID;
1613
Jens Axboe01de85e2006-10-17 19:50:36 +02001614 if (unlikely(kill && !capable(CAP_FSETID)))
1615 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616
Jens Axboe01de85e2006-10-17 19:50:36 +02001617 return 0;
1618}
Mark Fashehd23a1472006-10-17 17:05:18 -07001619EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001620
1621int __remove_suid(struct dentry *dentry, int kill)
1622{
1623 struct iattr newattrs;
1624
1625 newattrs.ia_valid = ATTR_FORCE | kill;
1626 return notify_change(dentry, &newattrs);
1627}
1628
1629int remove_suid(struct dentry *dentry)
1630{
Serge E. Hallynb5376772007-10-16 23:31:36 -07001631 int killsuid = should_remove_suid(dentry);
1632 int killpriv = security_inode_need_killpriv(dentry);
1633 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001634
Serge E. Hallynb5376772007-10-16 23:31:36 -07001635 if (killpriv < 0)
1636 return killpriv;
1637 if (killpriv)
1638 error = security_inode_killpriv(dentry);
1639 if (!error && killsuid)
1640 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001641
Serge E. Hallynb5376772007-10-16 23:31:36 -07001642 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643}
1644EXPORT_SYMBOL(remove_suid);
1645
Nick Piggin2f718ff2007-10-16 01:24:59 -07001646static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 const struct iovec *iov, size_t base, size_t bytes)
1648{
1649 size_t copied = 0, left = 0;
1650
1651 while (bytes) {
1652 char __user *buf = iov->iov_base + base;
1653 int copy = min(bytes, iov->iov_len - base);
1654
1655 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001656 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001657 copied += copy;
1658 bytes -= copy;
1659 vaddr += copy;
1660 iov++;
1661
NeilBrown01408c42006-06-25 05:47:58 -07001662 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 }
1665 return copied - left;
1666}
1667
1668/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001669 * Copy as much as we can into the page and return the number of bytes which
1670 * were sucessfully copied. If a fault is encountered then return the number of
1671 * bytes which were copied.
1672 */
1673size_t iov_iter_copy_from_user_atomic(struct page *page,
1674 struct iov_iter *i, unsigned long offset, size_t bytes)
1675{
1676 char *kaddr;
1677 size_t copied;
1678
1679 BUG_ON(!in_atomic());
1680 kaddr = kmap_atomic(page, KM_USER0);
1681 if (likely(i->nr_segs == 1)) {
1682 int left;
1683 char __user *buf = i->iov->iov_base + i->iov_offset;
1684 left = __copy_from_user_inatomic_nocache(kaddr + offset,
1685 buf, bytes);
1686 copied = bytes - left;
1687 } else {
1688 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1689 i->iov, i->iov_offset, bytes);
1690 }
1691 kunmap_atomic(kaddr, KM_USER0);
1692
1693 return copied;
1694}
Nick Piggin89e10782007-10-16 01:25:07 -07001695EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001696
1697/*
1698 * This has the same sideeffects and return value as
1699 * iov_iter_copy_from_user_atomic().
1700 * The difference is that it attempts to resolve faults.
1701 * Page must not be locked.
1702 */
1703size_t iov_iter_copy_from_user(struct page *page,
1704 struct iov_iter *i, unsigned long offset, size_t bytes)
1705{
1706 char *kaddr;
1707 size_t copied;
1708
1709 kaddr = kmap(page);
1710 if (likely(i->nr_segs == 1)) {
1711 int left;
1712 char __user *buf = i->iov->iov_base + i->iov_offset;
1713 left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
1714 copied = bytes - left;
1715 } else {
1716 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1717 i->iov, i->iov_offset, bytes);
1718 }
1719 kunmap(page);
1720 return copied;
1721}
Nick Piggin89e10782007-10-16 01:25:07 -07001722EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001723
1724static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
1725{
1726 if (likely(i->nr_segs == 1)) {
1727 i->iov_offset += bytes;
1728 } else {
1729 const struct iovec *iov = i->iov;
1730 size_t base = i->iov_offset;
1731
1732 while (bytes) {
1733 int copy = min(bytes, iov->iov_len - base);
1734
1735 bytes -= copy;
1736 base += copy;
1737 if (iov->iov_len == base) {
1738 iov++;
1739 base = 0;
1740 }
1741 }
1742 i->iov = iov;
1743 i->iov_offset = base;
1744 }
1745}
1746
1747void iov_iter_advance(struct iov_iter *i, size_t bytes)
1748{
1749 BUG_ON(i->count < bytes);
1750
1751 __iov_iter_advance_iov(i, bytes);
1752 i->count -= bytes;
1753}
Nick Piggin89e10782007-10-16 01:25:07 -07001754EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001755
Nick Pigginafddba42007-10-16 01:25:01 -07001756/*
1757 * Fault in the first iovec of the given iov_iter, to a maximum length
1758 * of bytes. Returns 0 on success, or non-zero if the memory could not be
1759 * accessed (ie. because it is an invalid address).
1760 *
1761 * writev-intensive code may want this to prefault several iovecs -- that
1762 * would be possible (callers must not rely on the fact that _only_ the
1763 * first iovec will be faulted with the current implementation).
1764 */
1765int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001766{
Nick Piggin2f718ff2007-10-16 01:24:59 -07001767 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07001768 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
1769 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001770}
Nick Piggin89e10782007-10-16 01:25:07 -07001771EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001772
1773/*
1774 * Return the count of just the current iov_iter segment.
1775 */
1776size_t iov_iter_single_seg_count(struct iov_iter *i)
1777{
1778 const struct iovec *iov = i->iov;
1779 if (i->nr_segs == 1)
1780 return i->count;
1781 else
1782 return min(i->count, iov->iov_len - i->iov_offset);
1783}
Nick Piggin89e10782007-10-16 01:25:07 -07001784EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001785
1786/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 * Performs necessary checks before doing a write
1788 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001789 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 * Returns appropriate error code that caller should return or
1791 * zero in case that write should be allowed.
1792 */
1793inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1794{
1795 struct inode *inode = file->f_mapping->host;
1796 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1797
1798 if (unlikely(*pos < 0))
1799 return -EINVAL;
1800
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801 if (!isblk) {
1802 /* FIXME: this is for backwards compatibility with 2.4 */
1803 if (file->f_flags & O_APPEND)
1804 *pos = i_size_read(inode);
1805
1806 if (limit != RLIM_INFINITY) {
1807 if (*pos >= limit) {
1808 send_sig(SIGXFSZ, current, 0);
1809 return -EFBIG;
1810 }
1811 if (*count > limit - (typeof(limit))*pos) {
1812 *count = limit - (typeof(limit))*pos;
1813 }
1814 }
1815 }
1816
1817 /*
1818 * LFS rule
1819 */
1820 if (unlikely(*pos + *count > MAX_NON_LFS &&
1821 !(file->f_flags & O_LARGEFILE))) {
1822 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823 return -EFBIG;
1824 }
1825 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1826 *count = MAX_NON_LFS - (unsigned long)*pos;
1827 }
1828 }
1829
1830 /*
1831 * Are we about to exceed the fs block limit ?
1832 *
1833 * If we have written data it becomes a short write. If we have
1834 * exceeded without writing data we send a signal and return EFBIG.
1835 * Linus frestrict idea will clean these up nicely..
1836 */
1837 if (likely(!isblk)) {
1838 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1839 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840 return -EFBIG;
1841 }
1842 /* zero-length writes at ->s_maxbytes are OK */
1843 }
1844
1845 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1846 *count = inode->i_sb->s_maxbytes - *pos;
1847 } else {
David Howells93614012006-09-30 20:45:40 +02001848#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 loff_t isize;
1850 if (bdev_read_only(I_BDEV(inode)))
1851 return -EPERM;
1852 isize = i_size_read(inode);
1853 if (*pos >= isize) {
1854 if (*count || *pos > isize)
1855 return -ENOSPC;
1856 }
1857
1858 if (*pos + *count > isize)
1859 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02001860#else
1861 return -EPERM;
1862#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 }
1864 return 0;
1865}
1866EXPORT_SYMBOL(generic_write_checks);
1867
Nick Pigginafddba42007-10-16 01:25:01 -07001868int pagecache_write_begin(struct file *file, struct address_space *mapping,
1869 loff_t pos, unsigned len, unsigned flags,
1870 struct page **pagep, void **fsdata)
1871{
1872 const struct address_space_operations *aops = mapping->a_ops;
1873
1874 if (aops->write_begin) {
1875 return aops->write_begin(file, mapping, pos, len, flags,
1876 pagep, fsdata);
1877 } else {
1878 int ret;
1879 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1880 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1881 struct inode *inode = mapping->host;
1882 struct page *page;
1883again:
1884 page = __grab_cache_page(mapping, index);
1885 *pagep = page;
1886 if (!page)
1887 return -ENOMEM;
1888
1889 if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
1890 /*
1891 * There is no way to resolve a short write situation
1892 * for a !Uptodate page (except by double copying in
1893 * the caller done by generic_perform_write_2copy).
1894 *
1895 * Instead, we have to bring it uptodate here.
1896 */
1897 ret = aops->readpage(file, page);
1898 page_cache_release(page);
1899 if (ret) {
1900 if (ret == AOP_TRUNCATED_PAGE)
1901 goto again;
1902 return ret;
1903 }
1904 goto again;
1905 }
1906
1907 ret = aops->prepare_write(file, page, offset, offset+len);
1908 if (ret) {
Nick Piggin55144762007-10-16 01:25:26 -07001909 unlock_page(page);
Nick Pigginafddba42007-10-16 01:25:01 -07001910 page_cache_release(page);
1911 if (pos + len > inode->i_size)
1912 vmtruncate(inode, inode->i_size);
Nick Pigginafddba42007-10-16 01:25:01 -07001913 }
1914 return ret;
1915 }
1916}
1917EXPORT_SYMBOL(pagecache_write_begin);
1918
1919int pagecache_write_end(struct file *file, struct address_space *mapping,
1920 loff_t pos, unsigned len, unsigned copied,
1921 struct page *page, void *fsdata)
1922{
1923 const struct address_space_operations *aops = mapping->a_ops;
1924 int ret;
1925
1926 if (aops->write_end) {
1927 mark_page_accessed(page);
1928 ret = aops->write_end(file, mapping, pos, len, copied,
1929 page, fsdata);
1930 } else {
1931 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1932 struct inode *inode = mapping->host;
1933
1934 flush_dcache_page(page);
1935 ret = aops->commit_write(file, page, offset, offset+len);
1936 unlock_page(page);
1937 mark_page_accessed(page);
1938 page_cache_release(page);
Nick Pigginafddba42007-10-16 01:25:01 -07001939
1940 if (ret < 0) {
1941 if (pos + len > inode->i_size)
1942 vmtruncate(inode, inode->i_size);
1943 } else if (ret > 0)
1944 ret = min_t(size_t, copied, ret);
1945 else
1946 ret = copied;
1947 }
1948
1949 return ret;
1950}
1951EXPORT_SYMBOL(pagecache_write_end);
1952
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953ssize_t
1954generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1955 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1956 size_t count, size_t ocount)
1957{
1958 struct file *file = iocb->ki_filp;
1959 struct address_space *mapping = file->f_mapping;
1960 struct inode *inode = mapping->host;
1961 ssize_t written;
1962
1963 if (count != ocount)
1964 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1965
1966 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1967 if (written > 0) {
1968 loff_t end = pos + written;
1969 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1970 i_size_write(inode, end);
1971 mark_inode_dirty(inode);
1972 }
1973 *ppos = end;
1974 }
1975
1976 /*
1977 * Sync the fs metadata but not the minor inode changes and
1978 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001979 * i_mutex is held, which protects generic_osync_inode() from
Zach Brown8459d862006-12-10 02:21:05 -08001980 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001981 */
Zach Brown8459d862006-12-10 02:21:05 -08001982 if ((written >= 0 || written == -EIOCBQUEUED) &&
1983 ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07001984 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
1985 if (err < 0)
1986 written = err;
1987 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988 return written;
1989}
1990EXPORT_SYMBOL(generic_file_direct_write);
1991
Nick Piggineb2be182007-10-16 01:24:57 -07001992/*
1993 * Find or create a page at the given pagecache position. Return the locked
1994 * page. This function is specifically for buffered writes.
1995 */
Nick Pigginafddba42007-10-16 01:25:01 -07001996struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index)
Nick Piggineb2be182007-10-16 01:24:57 -07001997{
1998 int status;
1999 struct page *page;
2000repeat:
2001 page = find_lock_page(mapping, index);
2002 if (likely(page))
2003 return page;
2004
2005 page = page_cache_alloc(mapping);
2006 if (!page)
2007 return NULL;
2008 status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
2009 if (unlikely(status)) {
2010 page_cache_release(page);
2011 if (status == -EEXIST)
2012 goto repeat;
2013 return NULL;
2014 }
2015 return page;
2016}
Nick Pigginafddba42007-10-16 01:25:01 -07002017EXPORT_SYMBOL(__grab_cache_page);
Nick Piggineb2be182007-10-16 01:24:57 -07002018
Nick Pigginafddba42007-10-16 01:25:01 -07002019static ssize_t generic_perform_write_2copy(struct file *file,
2020 struct iov_iter *i, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002021{
Andrew Mortonae374612007-10-16 01:24:55 -07002022 struct address_space *mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002023 const struct address_space_operations *a_ops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002024 struct inode *inode = mapping->host;
2025 long status = 0;
2026 ssize_t written = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027
2028 do {
Nick Piggin08291422007-10-16 01:24:59 -07002029 struct page *src_page;
Nick Piggineb2be182007-10-16 01:24:57 -07002030 struct page *page;
Andrew Mortonae374612007-10-16 01:24:55 -07002031 pgoff_t index; /* Pagecache index for current page */
2032 unsigned long offset; /* Offset into pagecache page */
Nick Piggin08291422007-10-16 01:24:59 -07002033 unsigned long bytes; /* Bytes to write to page */
Andrew Mortonae374612007-10-16 01:24:55 -07002034 size_t copied; /* Bytes copied from user */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035
Andrew Mortonae374612007-10-16 01:24:55 -07002036 offset = (pos & (PAGE_CACHE_SIZE - 1));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037 index = pos >> PAGE_CACHE_SHIFT;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002038 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
Nick Pigginafddba42007-10-16 01:25:01 -07002039 iov_iter_count(i));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040
Nick Piggin08291422007-10-16 01:24:59 -07002041 /*
2042 * a non-NULL src_page indicates that we're doing the
2043 * copy via get_user_pages and kmap.
2044 */
2045 src_page = NULL;
Andrew Mortonae374612007-10-16 01:24:55 -07002046
Nick Piggin41cb8ac2007-10-16 01:24:53 -07002047 /*
2048 * Bring in the user page that we will copy from _first_.
2049 * Otherwise there's a nasty deadlock on copying from the
2050 * same page as we're writing to, without it being marked
2051 * up-to-date.
Nick Piggin08291422007-10-16 01:24:59 -07002052 *
2053 * Not only is this an optimisation, but it is also required
2054 * to check that the address is actually valid, when atomic
2055 * usercopies are used, below.
Nick Piggin41cb8ac2007-10-16 01:24:53 -07002056 */
Nick Pigginafddba42007-10-16 01:25:01 -07002057 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
Nick Piggin08291422007-10-16 01:24:59 -07002058 status = -EFAULT;
2059 break;
2060 }
Nick Piggineb2be182007-10-16 01:24:57 -07002061
2062 page = __grab_cache_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 if (!page) {
2064 status = -ENOMEM;
2065 break;
2066 }
2067
Nick Piggin08291422007-10-16 01:24:59 -07002068 /*
2069 * non-uptodate pages cannot cope with short copies, and we
2070 * cannot take a pagefault with the destination page locked.
2071 * So pin the source page to copy it.
2072 */
Nick Piggin674b8922007-10-16 01:25:03 -07002073 if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
Nick Piggin08291422007-10-16 01:24:59 -07002074 unlock_page(page);
2075
2076 src_page = alloc_page(GFP_KERNEL);
2077 if (!src_page) {
2078 page_cache_release(page);
2079 status = -ENOMEM;
2080 break;
2081 }
2082
2083 /*
2084 * Cannot get_user_pages with a page locked for the
2085 * same reason as we can't take a page fault with a
2086 * page locked (as explained below).
2087 */
Nick Pigginafddba42007-10-16 01:25:01 -07002088 copied = iov_iter_copy_from_user(src_page, i,
Nick Piggin2f718ff2007-10-16 01:24:59 -07002089 offset, bytes);
Nick Piggin08291422007-10-16 01:24:59 -07002090 if (unlikely(copied == 0)) {
2091 status = -EFAULT;
2092 page_cache_release(page);
2093 page_cache_release(src_page);
2094 break;
2095 }
2096 bytes = copied;
2097
2098 lock_page(page);
2099 /*
2100 * Can't handle the page going uptodate here, because
2101 * that means we would use non-atomic usercopies, which
2102 * zero out the tail of the page, which can cause
2103 * zeroes to become transiently visible. We could just
2104 * use a non-zeroing copy, but the APIs aren't too
2105 * consistent.
2106 */
2107 if (unlikely(!page->mapping || PageUptodate(page))) {
2108 unlock_page(page);
2109 page_cache_release(page);
2110 page_cache_release(src_page);
2111 continue;
2112 }
Nick Piggin08291422007-10-16 01:24:59 -07002113 }
2114
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 status = a_ops->prepare_write(file, page, offset, offset+bytes);
Nick Piggin64649a52007-10-16 01:24:56 -07002116 if (unlikely(status))
2117 goto fs_write_aop_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08002118
Nick Piggin08291422007-10-16 01:24:59 -07002119 if (!src_page) {
2120 /*
2121 * Must not enter the pagefault handler here, because
2122 * we hold the page lock, so we might recursively
2123 * deadlock on the same lock, or get an ABBA deadlock
2124 * against a different lock, or against the mmap_sem
2125 * (which nests outside the page lock). So increment
2126 * preempt count, and use _atomic usercopies.
2127 *
2128 * The page is uptodate so we are OK to encounter a
2129 * short copy: if unmodified parts of the page are
2130 * marked dirty and written out to disk, it doesn't
2131 * really matter.
2132 */
2133 pagefault_disable();
Nick Pigginafddba42007-10-16 01:25:01 -07002134 copied = iov_iter_copy_from_user_atomic(page, i,
Nick Piggin2f718ff2007-10-16 01:24:59 -07002135 offset, bytes);
Nick Piggin08291422007-10-16 01:24:59 -07002136 pagefault_enable();
2137 } else {
2138 void *src, *dst;
2139 src = kmap_atomic(src_page, KM_USER0);
2140 dst = kmap_atomic(page, KM_USER1);
2141 memcpy(dst + offset, src + offset, bytes);
2142 kunmap_atomic(dst, KM_USER1);
2143 kunmap_atomic(src, KM_USER0);
2144 copied = bytes;
2145 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 flush_dcache_page(page);
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002147
Linus Torvalds1da177e2005-04-16 15:20:36 -07002148 status = a_ops->commit_write(file, page, offset, offset+bytes);
Nick Piggin55144762007-10-16 01:25:26 -07002149 if (unlikely(status < 0))
Nick Piggin64649a52007-10-16 01:24:56 -07002150 goto fs_write_aop_error;
Nick Piggin64649a52007-10-16 01:24:56 -07002151 if (unlikely(status > 0)) /* filesystem did partial write */
Nick Piggin08291422007-10-16 01:24:59 -07002152 copied = min_t(size_t, copied, status);
2153
2154 unlock_page(page);
2155 mark_page_accessed(page);
2156 page_cache_release(page);
2157 if (src_page)
2158 page_cache_release(src_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159
Nick Pigginafddba42007-10-16 01:25:01 -07002160 iov_iter_advance(i, copied);
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002161 pos += copied;
Nick Pigginafddba42007-10-16 01:25:01 -07002162 written += copied;
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002163
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 balance_dirty_pages_ratelimited(mapping);
2165 cond_resched();
Nick Piggin64649a52007-10-16 01:24:56 -07002166 continue;
2167
2168fs_write_aop_error:
Nick Piggin55144762007-10-16 01:25:26 -07002169 unlock_page(page);
Nick Piggin64649a52007-10-16 01:24:56 -07002170 page_cache_release(page);
Nick Piggin08291422007-10-16 01:24:59 -07002171 if (src_page)
2172 page_cache_release(src_page);
Nick Piggin64649a52007-10-16 01:24:56 -07002173
2174 /*
2175 * prepare_write() may have instantiated a few blocks
2176 * outside i_size. Trim these off again. Don't need
2177 * i_size_read because we hold i_mutex.
2178 */
2179 if (pos + bytes > inode->i_size)
2180 vmtruncate(inode, inode->i_size);
Nick Piggin55144762007-10-16 01:25:26 -07002181 break;
Nick Pigginafddba42007-10-16 01:25:01 -07002182 } while (iov_iter_count(i));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183
Nick Pigginafddba42007-10-16 01:25:01 -07002184 return written ? written : status;
2185}
2186
2187static ssize_t generic_perform_write(struct file *file,
2188 struct iov_iter *i, loff_t pos)
2189{
2190 struct address_space *mapping = file->f_mapping;
2191 const struct address_space_operations *a_ops = mapping->a_ops;
2192 long status = 0;
2193 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002194 unsigned int flags = 0;
2195
2196 /*
2197 * Copies from kernel address space cannot fail (NFSD is a big user).
2198 */
2199 if (segment_eq(get_fs(), KERNEL_DS))
2200 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002201
2202 do {
2203 struct page *page;
2204 pgoff_t index; /* Pagecache index for current page */
2205 unsigned long offset; /* Offset into pagecache page */
2206 unsigned long bytes; /* Bytes to write to page */
2207 size_t copied; /* Bytes copied from user */
2208 void *fsdata;
2209
2210 offset = (pos & (PAGE_CACHE_SIZE - 1));
2211 index = pos >> PAGE_CACHE_SHIFT;
2212 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2213 iov_iter_count(i));
2214
2215again:
2216
2217 /*
2218 * Bring in the user page that we will copy from _first_.
2219 * Otherwise there's a nasty deadlock on copying from the
2220 * same page as we're writing to, without it being marked
2221 * up-to-date.
2222 *
2223 * Not only is this an optimisation, but it is also required
2224 * to check that the address is actually valid, when atomic
2225 * usercopies are used, below.
2226 */
2227 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2228 status = -EFAULT;
2229 break;
2230 }
2231
Nick Piggin674b8922007-10-16 01:25:03 -07002232 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002233 &page, &fsdata);
2234 if (unlikely(status))
2235 break;
2236
2237 pagefault_disable();
2238 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2239 pagefault_enable();
2240 flush_dcache_page(page);
2241
2242 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2243 page, fsdata);
2244 if (unlikely(status < 0))
2245 break;
2246 copied = status;
2247
2248 cond_resched();
2249
2250 if (unlikely(copied == 0)) {
2251 /*
2252 * If we were unable to copy any data at all, we must
2253 * fall back to a single segment length write.
2254 *
2255 * If we didn't fallback here, we could livelock
2256 * because not all segments in the iov can be copied at
2257 * once without a pagefault.
2258 */
2259 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2260 iov_iter_single_seg_count(i));
2261 goto again;
2262 }
2263 iov_iter_advance(i, copied);
2264 pos += copied;
2265 written += copied;
2266
2267 balance_dirty_pages_ratelimited(mapping);
2268
2269 } while (iov_iter_count(i));
2270
2271 return written ? written : status;
2272}
2273
2274ssize_t
2275generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2276 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2277 size_t count, ssize_t written)
2278{
2279 struct file *file = iocb->ki_filp;
2280 struct address_space *mapping = file->f_mapping;
2281 const struct address_space_operations *a_ops = mapping->a_ops;
2282 struct inode *inode = mapping->host;
2283 ssize_t status;
2284 struct iov_iter i;
2285
2286 iov_iter_init(&i, iov, nr_segs, count, written);
2287 if (a_ops->write_begin)
2288 status = generic_perform_write(file, &i, pos);
2289 else
2290 status = generic_perform_write_2copy(file, &i, pos);
2291
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002293 written += status;
2294 *ppos = pos + status;
2295
2296 /*
2297 * For now, when the user asks for O_SYNC, we'll actually give
2298 * O_DSYNC
2299 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002300 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2301 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2302 status = generic_osync_inode(inode, mapping,
2303 OSYNC_METADATA|OSYNC_DATA);
2304 }
2305 }
2306
2307 /*
2308 * If we get here for O_DIRECT writes then we must have fallen through
2309 * to buffered writes (block instantiation inside i_size). So we sync
2310 * the file data here, to try to honour O_DIRECT expectations.
2311 */
2312 if (unlikely(file->f_flags & O_DIRECT) && written)
2313 status = filemap_write_and_wait(mapping);
2314
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315 return written ? written : status;
2316}
2317EXPORT_SYMBOL(generic_file_buffered_write);
2318
Adrian Bunk5ce78522005-09-10 00:26:28 -07002319static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002320__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2321 unsigned long nr_segs, loff_t *ppos)
2322{
2323 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002324 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 size_t ocount; /* original count */
2326 size_t count; /* after file limit checks */
2327 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328 loff_t pos;
2329 ssize_t written;
2330 ssize_t err;
2331
2332 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002333 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2334 if (err)
2335 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336
2337 count = ocount;
2338 pos = *ppos;
2339
2340 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2341
2342 /* We can write back this queue in page reclaim */
2343 current->backing_dev_info = mapping->backing_dev_info;
2344 written = 0;
2345
2346 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2347 if (err)
2348 goto out;
2349
2350 if (count == 0)
2351 goto out;
2352
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002353 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354 if (err)
2355 goto out;
2356
Christoph Hellwig870f4812006-01-09 20:52:01 -08002357 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002358
2359 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2360 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002361 loff_t endbyte;
2362 ssize_t written_buffered;
2363
2364 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2365 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002366 if (written < 0 || written == count)
2367 goto out;
2368 /*
2369 * direct-io write to a hole: fall through to buffered I/O
2370 * for completing the rest of the request.
2371 */
2372 pos += written;
2373 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002374 written_buffered = generic_file_buffered_write(iocb, iov,
2375 nr_segs, pos, ppos, count,
2376 written);
2377 /*
2378 * If generic_file_buffered_write() retuned a synchronous error
2379 * then we want to return the number of bytes which were
2380 * direct-written, or the error code if that was zero. Note
2381 * that this differs from normal direct-io semantics, which
2382 * will return -EFOO even if some bytes were written.
2383 */
2384 if (written_buffered < 0) {
2385 err = written_buffered;
2386 goto out;
2387 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002389 /*
2390 * We need to ensure that the page cache pages are written to
2391 * disk and invalidated to preserve the expected O_DIRECT
2392 * semantics.
2393 */
2394 endbyte = pos + written_buffered - written - 1;
Mark Fashehef51c972007-05-08 00:27:10 -07002395 err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
2396 SYNC_FILE_RANGE_WAIT_BEFORE|
2397 SYNC_FILE_RANGE_WRITE|
2398 SYNC_FILE_RANGE_WAIT_AFTER);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002399 if (err == 0) {
2400 written = written_buffered;
2401 invalidate_mapping_pages(mapping,
2402 pos >> PAGE_CACHE_SHIFT,
2403 endbyte >> PAGE_CACHE_SHIFT);
2404 } else {
2405 /*
2406 * We don't know how much we wrote, so just return
2407 * the number of bytes which were direct-written
2408 */
2409 }
2410 } else {
2411 written = generic_file_buffered_write(iocb, iov, nr_segs,
2412 pos, ppos, count, written);
2413 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414out:
2415 current->backing_dev_info = NULL;
2416 return written ? written : err;
2417}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418
Badari Pulavarty027445c2006-09-30 23:28:46 -07002419ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2420 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002421{
2422 struct file *file = iocb->ki_filp;
2423 struct address_space *mapping = file->f_mapping;
2424 struct inode *inode = mapping->host;
2425 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426
Badari Pulavarty027445c2006-09-30 23:28:46 -07002427 BUG_ON(iocb->ki_pos != pos);
2428
2429 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2430 &iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002431
2432 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Badari Pulavarty027445c2006-09-30 23:28:46 -07002433 ssize_t err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434
2435 err = sync_page_range_nolock(inode, mapping, pos, ret);
2436 if (err < 0)
2437 ret = err;
2438 }
2439 return ret;
2440}
Badari Pulavarty027445c2006-09-30 23:28:46 -07002441EXPORT_SYMBOL(generic_file_aio_write_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002442
Badari Pulavarty027445c2006-09-30 23:28:46 -07002443ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2444 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445{
2446 struct file *file = iocb->ki_filp;
2447 struct address_space *mapping = file->f_mapping;
2448 struct inode *inode = mapping->host;
2449 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002450
2451 BUG_ON(iocb->ki_pos != pos);
2452
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002453 mutex_lock(&inode->i_mutex);
Badari Pulavarty027445c2006-09-30 23:28:46 -07002454 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2455 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002456 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457
2458 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2459 ssize_t err;
2460
2461 err = sync_page_range(inode, mapping, pos, ret);
2462 if (err < 0)
2463 ret = err;
2464 }
2465 return ret;
2466}
2467EXPORT_SYMBOL(generic_file_aio_write);
2468
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002470 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471 * went wrong during pagecache shootdown.
2472 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002473static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2475 loff_t offset, unsigned long nr_segs)
2476{
2477 struct file *file = iocb->ki_filp;
2478 struct address_space *mapping = file->f_mapping;
2479 ssize_t retval;
Zach Brown65b82912007-03-16 13:38:11 -08002480 size_t write_len;
2481 pgoff_t end = 0; /* silence gcc */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002482
2483 /*
2484 * If it's a write, unmap all mmappings of the file up-front. This
2485 * will cause any pte dirty bits to be propagated into the pageframes
2486 * for the subsequent filemap_write_and_wait().
2487 */
2488 if (rw == WRITE) {
2489 write_len = iov_length(iov, nr_segs);
Zach Brown65b82912007-03-16 13:38:11 -08002490 end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002491 if (mapping_mapped(mapping))
2492 unmap_mapping_range(mapping, offset, write_len, 0);
2493 }
2494
2495 retval = filemap_write_and_wait(mapping);
Zach Brown65b82912007-03-16 13:38:11 -08002496 if (retval)
2497 goto out;
2498
2499 /*
2500 * After a write we want buffered reads to be sure to go to disk to get
2501 * the new data. We invalidate clean cached page from the region we're
2502 * about to write. We do this *before* the write so that we can return
2503 * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
2504 */
2505 if (rw == WRITE && mapping->nrpages) {
2506 retval = invalidate_inode_pages2_range(mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002507 offset >> PAGE_CACHE_SHIFT, end);
Zach Brown65b82912007-03-16 13:38:11 -08002508 if (retval)
2509 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510 }
Zach Brown65b82912007-03-16 13:38:11 -08002511
2512 retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
2513 if (retval)
2514 goto out;
2515
2516 /*
2517 * Finally, try again to invalidate clean pages which might have been
2518 * faulted in by get_user_pages() if the source of the write was an
2519 * mmap()ed region of the file we're writing. That's a pretty crazy
2520 * thing to do, so we don't support it 100%. If this invalidation
2521 * fails and we have -EIOCBQUEUED we ignore the failure.
2522 */
2523 if (rw == WRITE && mapping->nrpages) {
2524 int err = invalidate_inode_pages2_range(mapping,
2525 offset >> PAGE_CACHE_SHIFT, end);
2526 if (err && retval >= 0)
2527 retval = err;
2528 }
2529out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530 return retval;
2531}
David Howellscf9a2ae2006-08-29 19:05:54 +01002532
2533/**
2534 * try_to_release_page() - release old fs-specific metadata on a page
2535 *
2536 * @page: the page which the kernel is trying to free
2537 * @gfp_mask: memory allocation flags (and I/O mode)
2538 *
2539 * The address_space is to try to release any data against the page
2540 * (presumably at page->private). If the release was successful, return `1'.
2541 * Otherwise return zero.
2542 *
2543 * The @gfp_mask argument specifies whether I/O may be performed to release
2544 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2545 *
2546 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2547 */
2548int try_to_release_page(struct page *page, gfp_t gfp_mask)
2549{
2550 struct address_space * const mapping = page->mapping;
2551
2552 BUG_ON(!PageLocked(page));
2553 if (PageWriteback(page))
2554 return 0;
2555
2556 if (mapping && mapping->a_ops->releasepage)
2557 return mapping->a_ops->releasepage(page, gfp_mask);
2558 return try_to_free_buffers(page);
2559}
2560
2561EXPORT_SYMBOL(try_to_release_page);