blob: 5c74b68935acde87e1b9a91152b399a408509cf7 [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>
Emil Medve3a424f22007-10-24 14:18:32 +020031#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/security.h>
33#include <linux/syscalls.h>
Paul Jackson44110fe2006-03-24 03:16:04 -080034#include <linux/cpuset.h>
Nick Piggin2f718ff2007-10-16 01:24:59 -070035#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080036#include <linux/memcontrol.h>
Nick Piggin0f8053a2006-03-22 00:08:33 -080037#include "internal.h"
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 * FIXME: remove all knowledge of the buffer layer from the core VM
41 */
42#include <linux/buffer_head.h> /* for generic_osync_inode */
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044#include <asm/mman.h>
45
Adrian Bunk5ce78522005-09-10 00:26:28 -070046static ssize_t
47generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
48 loff_t offset, unsigned long nr_segs);
49
Linus Torvalds1da177e2005-04-16 15:20:36 -070050/*
51 * Shared mappings implemented 30.11.1994. It's not fully working yet,
52 * though.
53 *
54 * Shared mappings now work. 15.8.1995 Bruno.
55 *
56 * finished 'unifying' the page and buffer cache and SMP-threaded the
57 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
58 *
59 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
60 */
61
62/*
63 * Lock ordering:
64 *
65 * ->i_mmap_lock (vmtruncate)
66 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070067 * ->swap_lock (exclusive_swap_page, others)
68 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080070 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 * ->i_mmap_lock (truncate->unmap_mapping_range)
72 *
73 * ->mmap_sem
74 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070075 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
77 *
78 * ->mmap_sem
79 * ->lock_page (access_process_vm)
80 *
Nick Piggin82591e62006-10-19 23:29:10 -070081 * ->i_mutex (generic_file_buffered_write)
82 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080084 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 * ->i_alloc_sem (various)
86 *
87 * ->inode_lock
88 * ->sb_lock (fs/fs-writeback.c)
89 * ->mapping->tree_lock (__sync_single_inode)
90 *
91 * ->i_mmap_lock
92 * ->anon_vma.lock (vma_adjust)
93 *
94 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070095 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070097 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070098 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 * ->private_lock (try_to_unmap_one)
100 * ->tree_lock (try_to_unmap_one)
101 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -0800102 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103 * ->private_lock (page_remove_rmap->set_page_dirty)
104 * ->tree_lock (page_remove_rmap->set_page_dirty)
105 * ->inode_lock (page_remove_rmap->set_page_dirty)
106 * ->inode_lock (zap_pte_range->set_page_dirty)
107 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
108 *
109 * ->task->proc_lock
110 * ->dcache_lock (proc_pid_lookup)
111 */
112
113/*
114 * Remove a page from the page cache and free it. Caller has to make
115 * sure the page is locked and that nobody else uses it - or that usage
116 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
117 */
118void __remove_from_page_cache(struct page *page)
119{
120 struct address_space *mapping = page->mapping;
121
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800122 mem_cgroup_uncharge_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 radix_tree_delete(&mapping->page_tree, page->index);
124 page->mapping = NULL;
125 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700126 __dec_zone_page_state(page, NR_FILE_PAGES);
Nick Piggin45426812007-07-15 23:38:12 -0700127 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800128
129 /*
130 * Some filesystems seem to re-dirty the page even after
131 * the VM has canceled the dirty bit (eg ext3 journaling).
132 *
133 * Fix it up by doing a final dirty accounting check after
134 * having removed the page entirely.
135 */
136 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
137 dec_zone_page_state(page, NR_FILE_DIRTY);
138 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
139 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140}
141
142void remove_from_page_cache(struct page *page)
143{
144 struct address_space *mapping = page->mapping;
145
Matt Mackallcd7619d2005-05-01 08:59:01 -0700146 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
148 write_lock_irq(&mapping->tree_lock);
149 __remove_from_page_cache(page);
150 write_unlock_irq(&mapping->tree_lock);
151}
152
153static int sync_page(void *word)
154{
155 struct address_space *mapping;
156 struct page *page;
157
Andi Kleen07808b72005-11-05 17:25:53 +0100158 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159
160 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700161 * page_mapping() is being called without PG_locked held.
162 * Some knowledge of the state and use of the page is used to
163 * reduce the requirements down to a memory barrier.
164 * The danger here is of a stale page_mapping() return value
165 * indicating a struct address_space different from the one it's
166 * associated with when it is associated with one.
167 * After smp_mb(), it's either the correct page_mapping() for
168 * the page, or an old page_mapping() and the page's own
169 * page_mapping() has gone NULL.
170 * The ->sync_page() address_space operation must tolerate
171 * page_mapping() going NULL. By an amazing coincidence,
172 * this comes about because none of the users of the page
173 * in the ->sync_page() methods make essential use of the
174 * page_mapping(), merely passing the page down to the backing
175 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700176 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700177 * of interest. When page_mapping() does go NULL, the entire
178 * call stack gracefully ignores the page and returns.
179 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 */
181 smp_mb();
182 mapping = page_mapping(page);
183 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
184 mapping->a_ops->sync_page(page);
185 io_schedule();
186 return 0;
187}
188
Matthew Wilcox2687a352007-12-06 11:18:49 -0500189static int sync_page_killable(void *word)
190{
191 sync_page(word);
192 return fatal_signal_pending(current) ? -EINTR : 0;
193}
194
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700196 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700197 * @mapping: address space structure to write
198 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800199 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700200 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700202 * Start writeback against all of a mapping's dirty pages that lie
203 * within the byte offsets <start, end> inclusive.
204 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700206 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 * these two operations is that if a dirty page/buffer is encountered, it must
208 * be waited upon, and not just skipped over.
209 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800210int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
211 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212{
213 int ret;
214 struct writeback_control wbc = {
215 .sync_mode = sync_mode,
216 .nr_to_write = mapping->nrpages * 2,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700217 .range_start = start,
218 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 };
220
221 if (!mapping_cap_writeback_dirty(mapping))
222 return 0;
223
224 ret = do_writepages(mapping, &wbc);
225 return ret;
226}
227
228static inline int __filemap_fdatawrite(struct address_space *mapping,
229 int sync_mode)
230{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700231 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232}
233
234int filemap_fdatawrite(struct address_space *mapping)
235{
236 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
237}
238EXPORT_SYMBOL(filemap_fdatawrite);
239
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800240static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
241 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242{
243 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
244}
245
Randy Dunlap485bb992006-06-23 02:03:49 -0700246/**
247 * filemap_flush - mostly a non-blocking flush
248 * @mapping: target address_space
249 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 * This is a mostly non-blocking flush. Not suitable for data-integrity
251 * purposes - I/O may not be started against all dirty pages.
252 */
253int filemap_flush(struct address_space *mapping)
254{
255 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
256}
257EXPORT_SYMBOL(filemap_flush);
258
Randy Dunlap485bb992006-06-23 02:03:49 -0700259/**
260 * wait_on_page_writeback_range - wait for writeback to complete
261 * @mapping: target address_space
262 * @start: beginning page index
263 * @end: ending page index
264 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 * Wait for writeback to complete against pages indexed by start->end
266 * inclusive
267 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800268int wait_on_page_writeback_range(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 pgoff_t start, pgoff_t end)
270{
271 struct pagevec pvec;
272 int nr_pages;
273 int ret = 0;
274 pgoff_t index;
275
276 if (end < start)
277 return 0;
278
279 pagevec_init(&pvec, 0);
280 index = start;
281 while ((index <= end) &&
282 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
283 PAGECACHE_TAG_WRITEBACK,
284 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
285 unsigned i;
286
287 for (i = 0; i < nr_pages; i++) {
288 struct page *page = pvec.pages[i];
289
290 /* until radix tree lookup accepts end_index */
291 if (page->index > end)
292 continue;
293
294 wait_on_page_writeback(page);
295 if (PageError(page))
296 ret = -EIO;
297 }
298 pagevec_release(&pvec);
299 cond_resched();
300 }
301
302 /* Check for outstanding write errors */
303 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
304 ret = -ENOSPC;
305 if (test_and_clear_bit(AS_EIO, &mapping->flags))
306 ret = -EIO;
307
308 return ret;
309}
310
Randy Dunlap485bb992006-06-23 02:03:49 -0700311/**
312 * sync_page_range - write and wait on all pages in the passed range
313 * @inode: target inode
314 * @mapping: target address_space
315 * @pos: beginning offset in pages to write
316 * @count: number of bytes to write
317 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 * Write and wait upon all the pages in the passed range. This is a "data
319 * integrity" operation. It waits upon in-flight writeout before starting and
320 * waiting upon new writeout. If there was an IO error, return it.
321 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800322 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 * it is otherwise livelockable.
324 */
325int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800326 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327{
328 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
329 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
330 int ret;
331
332 if (!mapping_cap_writeback_dirty(mapping) || !count)
333 return 0;
334 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
335 if (ret == 0) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800336 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800338 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 }
340 if (ret == 0)
341 ret = wait_on_page_writeback_range(mapping, start, end);
342 return ret;
343}
344EXPORT_SYMBOL(sync_page_range);
345
Randy Dunlap485bb992006-06-23 02:03:49 -0700346/**
347 * sync_page_range_nolock
348 * @inode: target inode
349 * @mapping: target address_space
350 * @pos: beginning offset in pages to write
351 * @count: number of bytes to write
352 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800353 * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 * as it forces O_SYNC writers to different parts of the same file
355 * to be serialised right until io completion.
356 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800357int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
358 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359{
360 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
361 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
362 int ret;
363
364 if (!mapping_cap_writeback_dirty(mapping) || !count)
365 return 0;
366 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
367 if (ret == 0)
368 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
369 if (ret == 0)
370 ret = wait_on_page_writeback_range(mapping, start, end);
371 return ret;
372}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800373EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374
375/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700376 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700378 *
379 * Walk the list of under-writeback pages of the given address space
380 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 */
382int filemap_fdatawait(struct address_space *mapping)
383{
384 loff_t i_size = i_size_read(mapping->host);
385
386 if (i_size == 0)
387 return 0;
388
389 return wait_on_page_writeback_range(mapping, 0,
390 (i_size - 1) >> PAGE_CACHE_SHIFT);
391}
392EXPORT_SYMBOL(filemap_fdatawait);
393
394int filemap_write_and_wait(struct address_space *mapping)
395{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800396 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397
398 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800399 err = filemap_fdatawrite(mapping);
400 /*
401 * Even if the above returned error, the pages may be
402 * written partially (e.g. -ENOSPC), so we wait for it.
403 * But the -EIO is special case, it may indicate the worst
404 * thing (e.g. bug) happened, so we avoid waiting for it.
405 */
406 if (err != -EIO) {
407 int err2 = filemap_fdatawait(mapping);
408 if (!err)
409 err = err2;
410 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800412 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800414EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415
Randy Dunlap485bb992006-06-23 02:03:49 -0700416/**
417 * filemap_write_and_wait_range - write out & wait on a file range
418 * @mapping: the address_space for the pages
419 * @lstart: offset in bytes where the range starts
420 * @lend: offset in bytes where the range ends (inclusive)
421 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800422 * Write out and wait upon file offsets lstart->lend, inclusive.
423 *
424 * Note that `lend' is inclusive (describes the last byte to be written) so
425 * that this function can be used to write to the very end-of-file (end = -1).
426 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427int filemap_write_and_wait_range(struct address_space *mapping,
428 loff_t lstart, loff_t lend)
429{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800430 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
432 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800433 err = __filemap_fdatawrite_range(mapping, lstart, lend,
434 WB_SYNC_ALL);
435 /* See comment of filemap_write_and_wait() */
436 if (err != -EIO) {
437 int err2 = wait_on_page_writeback_range(mapping,
438 lstart >> PAGE_CACHE_SHIFT,
439 lend >> PAGE_CACHE_SHIFT);
440 if (!err)
441 err = err2;
442 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800444 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445}
446
Randy Dunlap485bb992006-06-23 02:03:49 -0700447/**
448 * add_to_page_cache - add newly allocated pagecache pages
449 * @page: page to add
450 * @mapping: the page's address_space
451 * @offset: page index
452 * @gfp_mask: page allocation mode
453 *
454 * This function is used to add newly allocated pagecache pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 * the page is new, so we can just run SetPageLocked() against it.
456 * The other page state flags were set by rmqueue().
457 *
458 * This function does not add the page to the LRU. The caller must do that.
459 */
460int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400461 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462{
Badari Pulavarty4c6bc8d2008-02-07 00:14:05 -0800463 int error = mem_cgroup_cache_charge(page, current->mm,
464 gfp_mask & ~__GFP_HIGHMEM);
Balbir Singh35c754d2008-02-07 00:14:05 -0800465 if (error)
466 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467
Balbir Singh35c754d2008-02-07 00:14:05 -0800468 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 if (error == 0) {
470 write_lock_irq(&mapping->tree_lock);
471 error = radix_tree_insert(&mapping->page_tree, offset, page);
472 if (!error) {
473 page_cache_get(page);
474 SetPageLocked(page);
475 page->mapping = mapping;
476 page->index = offset;
477 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700478 __inc_zone_page_state(page, NR_FILE_PAGES);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800479 } else
480 mem_cgroup_uncharge_page(page);
481
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 write_unlock_irq(&mapping->tree_lock);
483 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800484 } else
485 mem_cgroup_uncharge_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800486out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487 return error;
488}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489EXPORT_SYMBOL(add_to_page_cache);
490
491int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400492 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493{
494 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
495 if (ret == 0)
496 lru_cache_add(page);
497 return ret;
498}
499
Paul Jackson44110fe2006-03-24 03:16:04 -0800500#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700501struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800502{
503 if (cpuset_do_page_mem_spread()) {
504 int n = cpuset_mem_spread_node();
Nick Piggin2ae88142006-10-28 10:38:23 -0700505 return alloc_pages_node(n, gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800506 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700507 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800508}
Nick Piggin2ae88142006-10-28 10:38:23 -0700509EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800510#endif
511
Nick Piggindb376482006-09-25 23:31:24 -0700512static int __sleep_on_page_lock(void *word)
513{
514 io_schedule();
515 return 0;
516}
517
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518/*
519 * In order to wait for pages to become available there must be
520 * waitqueues associated with pages. By using a hash table of
521 * waitqueues where the bucket discipline is to maintain all
522 * waiters on the same queue and wake all when any of the pages
523 * become available, and for the woken contexts to check to be
524 * sure the appropriate page became available, this saves space
525 * at a cost of "thundering herd" phenomena during rare hash
526 * collisions.
527 */
528static wait_queue_head_t *page_waitqueue(struct page *page)
529{
530 const struct zone *zone = page_zone(page);
531
532 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
533}
534
535static inline void wake_up_page(struct page *page, int bit)
536{
537 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
538}
539
Harvey Harrison920c7a52008-02-04 22:29:26 -0800540void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541{
542 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
543
544 if (test_bit(bit_nr, &page->flags))
545 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
546 TASK_UNINTERRUPTIBLE);
547}
548EXPORT_SYMBOL(wait_on_page_bit);
549
550/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700551 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 * @page: the page
553 *
554 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
555 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
556 * mechananism between PageLocked pages and PageWriteback pages is shared.
557 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
558 *
559 * The first mb is necessary to safely close the critical section opened by the
560 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
561 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
562 * parallel wait_on_page_locked()).
563 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800564void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565{
566 smp_mb__before_clear_bit();
567 if (!TestClearPageLocked(page))
568 BUG();
569 smp_mb__after_clear_bit();
570 wake_up_page(page, PG_locked);
571}
572EXPORT_SYMBOL(unlock_page);
573
Randy Dunlap485bb992006-06-23 02:03:49 -0700574/**
575 * end_page_writeback - end writeback against a page
576 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 */
578void end_page_writeback(struct page *page)
579{
580 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
581 if (!test_clear_page_writeback(page))
582 BUG();
583 }
584 smp_mb__after_clear_bit();
585 wake_up_page(page, PG_writeback);
586}
587EXPORT_SYMBOL(end_page_writeback);
588
Randy Dunlap485bb992006-06-23 02:03:49 -0700589/**
590 * __lock_page - get a lock on the page, assuming we need to sleep to get it
591 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700593 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
595 * chances are that on the second loop, the block layer's plug list is empty,
596 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
597 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800598void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599{
600 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
601
602 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
603 TASK_UNINTERRUPTIBLE);
604}
605EXPORT_SYMBOL(__lock_page);
606
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800607int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500608{
609 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
610
611 return __wait_on_bit_lock(page_waitqueue(page), &wait,
612 sync_page_killable, TASK_KILLABLE);
613}
614
Nick Piggindb376482006-09-25 23:31:24 -0700615/*
616 * Variant of lock_page that does not require the caller to hold a reference
617 * on the page's mapping.
618 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800619void __lock_page_nosync(struct page *page)
Nick Piggindb376482006-09-25 23:31:24 -0700620{
621 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
622 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
623 TASK_UNINTERRUPTIBLE);
624}
625
Randy Dunlap485bb992006-06-23 02:03:49 -0700626/**
627 * find_get_page - find and get a page reference
628 * @mapping: the address_space to search
629 * @offset: the page index
630 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700631 * Is there a pagecache struct page at the given (mapping, offset) tuple?
632 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 */
Fengguang Wu57f6b962007-10-16 01:24:37 -0700634struct page * find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635{
636 struct page *page;
637
638 read_lock_irq(&mapping->tree_lock);
639 page = radix_tree_lookup(&mapping->page_tree, offset);
640 if (page)
641 page_cache_get(page);
642 read_unlock_irq(&mapping->tree_lock);
643 return page;
644}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645EXPORT_SYMBOL(find_get_page);
646
Randy Dunlap485bb992006-06-23 02:03:49 -0700647/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700649 * @mapping: the address_space to search
650 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 *
652 * Locates the desired pagecache page, locks it, increments its reference
653 * count and returns its address.
654 *
655 * Returns zero if the page was not present. find_lock_page() may sleep.
656 */
657struct page *find_lock_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700658 pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659{
660 struct page *page;
661
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662repeat:
Nick Piggin45726cb2007-10-16 01:24:41 -0700663 read_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700664 page = radix_tree_lookup(&mapping->page_tree, offset);
665 if (page) {
666 page_cache_get(page);
667 if (TestSetPageLocked(page)) {
668 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800669 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670
671 /* Has the page been truncated while we slept? */
Nick Piggin45726cb2007-10-16 01:24:41 -0700672 if (unlikely(page->mapping != mapping)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 unlock_page(page);
674 page_cache_release(page);
675 goto repeat;
676 }
Nick Piggin45726cb2007-10-16 01:24:41 -0700677 VM_BUG_ON(page->index != offset);
678 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 }
680 }
681 read_unlock_irq(&mapping->tree_lock);
Nick Piggin45726cb2007-10-16 01:24:41 -0700682out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 return page;
684}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685EXPORT_SYMBOL(find_lock_page);
686
687/**
688 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700689 * @mapping: the page's address_space
690 * @index: the page's index into the mapping
691 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 *
693 * Locates a page in the pagecache. If the page is not present, a new page
694 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
695 * LRU list. The returned page is locked and has its reference count
696 * incremented.
697 *
698 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
699 * allocation!
700 *
701 * find_or_create_page() returns the desired page's address, or zero on
702 * memory exhaustion.
703 */
704struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700705 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706{
Nick Piggineb2be182007-10-16 01:24:57 -0700707 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 int err;
709repeat:
710 page = find_lock_page(mapping, index);
711 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700712 page = __page_cache_alloc(gfp_mask);
713 if (!page)
714 return NULL;
715 err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
716 if (unlikely(err)) {
717 page_cache_release(page);
718 page = NULL;
719 if (err == -EEXIST)
720 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 return page;
724}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725EXPORT_SYMBOL(find_or_create_page);
726
727/**
728 * find_get_pages - gang pagecache lookup
729 * @mapping: The address_space to search
730 * @start: The starting page index
731 * @nr_pages: The maximum number of pages
732 * @pages: Where the resulting pages are placed
733 *
734 * find_get_pages() will search for and return a group of up to
735 * @nr_pages pages in the mapping. The pages are placed at @pages.
736 * find_get_pages() takes a reference against the returned pages.
737 *
738 * The search returns a group of mapping-contiguous pages with ascending
739 * indexes. There may be holes in the indices due to not-present pages.
740 *
741 * find_get_pages() returns the number of pages which were found.
742 */
743unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
744 unsigned int nr_pages, struct page **pages)
745{
746 unsigned int i;
747 unsigned int ret;
748
749 read_lock_irq(&mapping->tree_lock);
750 ret = radix_tree_gang_lookup(&mapping->page_tree,
751 (void **)pages, start, nr_pages);
752 for (i = 0; i < ret; i++)
753 page_cache_get(pages[i]);
754 read_unlock_irq(&mapping->tree_lock);
755 return ret;
756}
757
Jens Axboeebf43502006-04-27 08:46:01 +0200758/**
759 * find_get_pages_contig - gang contiguous pagecache lookup
760 * @mapping: The address_space to search
761 * @index: The starting page index
762 * @nr_pages: The maximum number of pages
763 * @pages: Where the resulting pages are placed
764 *
765 * find_get_pages_contig() works exactly like find_get_pages(), except
766 * that the returned number of pages are guaranteed to be contiguous.
767 *
768 * find_get_pages_contig() returns the number of pages which were found.
769 */
770unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
771 unsigned int nr_pages, struct page **pages)
772{
773 unsigned int i;
774 unsigned int ret;
775
776 read_lock_irq(&mapping->tree_lock);
777 ret = radix_tree_gang_lookup(&mapping->page_tree,
778 (void **)pages, index, nr_pages);
779 for (i = 0; i < ret; i++) {
780 if (pages[i]->mapping == NULL || pages[i]->index != index)
781 break;
782
783 page_cache_get(pages[i]);
784 index++;
785 }
786 read_unlock_irq(&mapping->tree_lock);
787 return i;
788}
David Howellsef71c152007-05-09 02:33:44 -0700789EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200790
Randy Dunlap485bb992006-06-23 02:03:49 -0700791/**
792 * find_get_pages_tag - find and return pages that match @tag
793 * @mapping: the address_space to search
794 * @index: the starting page index
795 * @tag: the tag index
796 * @nr_pages: the maximum number of pages
797 * @pages: where the resulting pages are placed
798 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700800 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 */
802unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
803 int tag, unsigned int nr_pages, struct page **pages)
804{
805 unsigned int i;
806 unsigned int ret;
807
808 read_lock_irq(&mapping->tree_lock);
809 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
810 (void **)pages, *index, nr_pages, tag);
811 for (i = 0; i < ret; i++)
812 page_cache_get(pages[i]);
813 if (ret)
814 *index = pages[ret - 1]->index + 1;
815 read_unlock_irq(&mapping->tree_lock);
816 return ret;
817}
David Howellsef71c152007-05-09 02:33:44 -0700818EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819
Randy Dunlap485bb992006-06-23 02:03:49 -0700820/**
821 * grab_cache_page_nowait - returns locked page at given index in given cache
822 * @mapping: target address_space
823 * @index: the page index
824 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800825 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 * This is intended for speculative data generators, where the data can
827 * be regenerated if the page couldn't be grabbed. This routine should
828 * be safe to call while holding the lock for another page.
829 *
830 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
831 * and deadlock against the caller's locked page.
832 */
833struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700834grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835{
836 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837
838 if (page) {
839 if (!TestSetPageLocked(page))
840 return page;
841 page_cache_release(page);
842 return NULL;
843 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700844 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
845 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700846 page_cache_release(page);
847 page = NULL;
848 }
849 return page;
850}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851EXPORT_SYMBOL(grab_cache_page_nowait);
852
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700853/*
854 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
855 * a _large_ part of the i/o request. Imagine the worst scenario:
856 *
857 * ---R__________________________________________B__________
858 * ^ reading here ^ bad block(assume 4k)
859 *
860 * read(R) => miss => readahead(R...B) => media error => frustrating retries
861 * => failing the whole request => read(R) => read(R+1) =>
862 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
863 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
864 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
865 *
866 * It is going insane. Fix it by quickly scaling down the readahead size.
867 */
868static void shrink_readahead_size_eio(struct file *filp,
869 struct file_ra_state *ra)
870{
871 if (!ra->ra_pages)
872 return;
873
874 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700875}
876
Randy Dunlap485bb992006-06-23 02:03:49 -0700877/**
Christoph Hellwig36e78912008-02-08 04:21:24 -0800878 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -0700879 * @filp: the file to read
880 * @ppos: current file position
881 * @desc: read_descriptor
882 * @actor: read method
883 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700885 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 *
887 * This is really ugly. But the goto's actually try to clarify some
888 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 */
Christoph Hellwig36e78912008-02-08 04:21:24 -0800890static void do_generic_file_read(struct file *filp, loff_t *ppos,
891 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892{
Christoph Hellwig36e78912008-02-08 04:21:24 -0800893 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -0800895 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700896 pgoff_t index;
897 pgoff_t last_index;
898 pgoff_t prev_index;
899 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -0700900 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700902
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -0700904 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
905 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
907 offset = *ppos & ~PAGE_CACHE_MASK;
908
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 for (;;) {
910 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700911 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -0700912 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 unsigned long nr, ret;
914
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916find_page:
917 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700918 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -0700919 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -0700920 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700921 index, last_index - index);
922 page = find_get_page(mapping, index);
923 if (unlikely(page == NULL))
924 goto no_cached_page;
925 }
926 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -0700927 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -0700928 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700929 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 }
931 if (!PageUptodate(page))
932 goto page_not_up_to_date;
933page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -0700934 /*
935 * i_size must be checked after we know the page is Uptodate.
936 *
937 * Checking i_size after the check allows us to calculate
938 * the correct value for "nr", which means the zero-filled
939 * part of the page is not copied back to userspace (unless
940 * another truncate extends the file - this is desired though).
941 */
942
943 isize = i_size_read(inode);
944 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
945 if (unlikely(!isize || index > end_index)) {
946 page_cache_release(page);
947 goto out;
948 }
949
950 /* nr is the maximum number of bytes to copy from this page */
951 nr = PAGE_CACHE_SIZE;
952 if (index == end_index) {
953 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
954 if (nr <= offset) {
955 page_cache_release(page);
956 goto out;
957 }
958 }
959 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700960
961 /* If users can be writing to this page using arbitrary
962 * virtual addresses, take care about potential aliasing
963 * before reading the page on the kernel side.
964 */
965 if (mapping_writably_mapped(mapping))
966 flush_dcache_page(page);
967
968 /*
Jan Karaec0f1632007-05-06 14:49:25 -0700969 * When a sequential read accesses a page several times,
970 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 */
Jan Karaec0f1632007-05-06 14:49:25 -0700972 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 mark_page_accessed(page);
974 prev_index = index;
975
976 /*
977 * Ok, we have the page, and it's up-to-date, so
978 * now we can copy it to user space...
979 *
980 * The actor routine returns how many bytes were actually used..
981 * NOTE! This may not be the same as how much of a user buffer
982 * we filled up (we may be padding etc), so we can only update
983 * "pos" here (the actor routine has to update the user buffer
984 * pointers and the remaining count).
985 */
986 ret = actor(desc, page, offset, nr);
987 offset += ret;
988 index += offset >> PAGE_CACHE_SHIFT;
989 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -0700990 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991
992 page_cache_release(page);
993 if (ret == nr && desc->count)
994 continue;
995 goto out;
996
997page_not_up_to_date:
998 /* Get exclusive access to the page ... */
Matthew Wilcox0b94e972007-12-06 11:19:57 -0500999 if (lock_page_killable(page))
1000 goto readpage_eio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001
Nick Pigginda6052f2006-09-25 23:31:35 -07001002 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 if (!page->mapping) {
1004 unlock_page(page);
1005 page_cache_release(page);
1006 continue;
1007 }
1008
1009 /* Did somebody else fill it already? */
1010 if (PageUptodate(page)) {
1011 unlock_page(page);
1012 goto page_ok;
1013 }
1014
1015readpage:
1016 /* Start the actual read. The read will unlock the page. */
1017 error = mapping->a_ops->readpage(filp, page);
1018
Zach Brown994fc28c2005-12-15 14:28:17 -08001019 if (unlikely(error)) {
1020 if (error == AOP_TRUNCATED_PAGE) {
1021 page_cache_release(page);
1022 goto find_page;
1023 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001025 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026
1027 if (!PageUptodate(page)) {
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001028 if (lock_page_killable(page))
1029 goto readpage_eio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 if (!PageUptodate(page)) {
1031 if (page->mapping == NULL) {
1032 /*
1033 * invalidate_inode_pages got it
1034 */
1035 unlock_page(page);
1036 page_cache_release(page);
1037 goto find_page;
1038 }
1039 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001040 shrink_readahead_size_eio(filp, ra);
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001041 goto readpage_eio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 }
1043 unlock_page(page);
1044 }
1045
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046 goto page_ok;
1047
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001048readpage_eio:
1049 error = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050readpage_error:
1051 /* UHHUH! A synchronous read error occurred. Report it */
1052 desc->error = error;
1053 page_cache_release(page);
1054 goto out;
1055
1056no_cached_page:
1057 /*
1058 * Ok, it wasn't cached, so we need to create a new
1059 * page..
1060 */
Nick Piggineb2be182007-10-16 01:24:57 -07001061 page = page_cache_alloc_cold(mapping);
1062 if (!page) {
1063 desc->error = -ENOMEM;
1064 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 }
Nick Piggineb2be182007-10-16 01:24:57 -07001066 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 index, GFP_KERNEL);
1068 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001069 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 if (error == -EEXIST)
1071 goto find_page;
1072 desc->error = error;
1073 goto out;
1074 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 goto readpage;
1076 }
1077
1078out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001079 ra->prev_pos = prev_index;
1080 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1081 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001083 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 if (filp)
1085 file_accessed(filp);
1086}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087
1088int file_read_actor(read_descriptor_t *desc, struct page *page,
1089 unsigned long offset, unsigned long size)
1090{
1091 char *kaddr;
1092 unsigned long left, count = desc->count;
1093
1094 if (size > count)
1095 size = count;
1096
1097 /*
1098 * Faults on the destination of a read are common, so do it before
1099 * taking the kmap.
1100 */
1101 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1102 kaddr = kmap_atomic(page, KM_USER0);
1103 left = __copy_to_user_inatomic(desc->arg.buf,
1104 kaddr + offset, size);
1105 kunmap_atomic(kaddr, KM_USER0);
1106 if (left == 0)
1107 goto success;
1108 }
1109
1110 /* Do it the slow way */
1111 kaddr = kmap(page);
1112 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1113 kunmap(page);
1114
1115 if (left) {
1116 size -= left;
1117 desc->error = -EFAULT;
1118 }
1119success:
1120 desc->count = count - size;
1121 desc->written += size;
1122 desc->arg.buf += size;
1123 return size;
1124}
1125
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001126/*
1127 * Performs necessary checks before doing a write
1128 * @iov: io vector request
1129 * @nr_segs: number of segments in the iovec
1130 * @count: number of bytes to write
1131 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1132 *
1133 * Adjust number of segments and amount of bytes to write (nr_segs should be
1134 * properly initialized first). Returns appropriate error code that caller
1135 * should return or zero in case that write should be allowed.
1136 */
1137int generic_segment_checks(const struct iovec *iov,
1138 unsigned long *nr_segs, size_t *count, int access_flags)
1139{
1140 unsigned long seg;
1141 size_t cnt = 0;
1142 for (seg = 0; seg < *nr_segs; seg++) {
1143 const struct iovec *iv = &iov[seg];
1144
1145 /*
1146 * If any segment has a negative length, or the cumulative
1147 * length ever wraps negative then return -EINVAL.
1148 */
1149 cnt += iv->iov_len;
1150 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1151 return -EINVAL;
1152 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1153 continue;
1154 if (seg == 0)
1155 return -EFAULT;
1156 *nr_segs = seg;
1157 cnt -= iv->iov_len; /* This segment is no good */
1158 break;
1159 }
1160 *count = cnt;
1161 return 0;
1162}
1163EXPORT_SYMBOL(generic_segment_checks);
1164
Randy Dunlap485bb992006-06-23 02:03:49 -07001165/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001166 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001167 * @iocb: kernel I/O control block
1168 * @iov: io vector request
1169 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001170 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001171 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 * This is the "read()" routine for all filesystems
1173 * that can use the page cache directly.
1174 */
1175ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001176generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1177 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178{
1179 struct file *filp = iocb->ki_filp;
1180 ssize_t retval;
1181 unsigned long seg;
1182 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001183 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184
1185 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001186 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1187 if (retval)
1188 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189
1190 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1191 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001192 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 struct address_space *mapping;
1194 struct inode *inode;
1195
1196 mapping = filp->f_mapping;
1197 inode = mapping->host;
1198 retval = 0;
1199 if (!count)
1200 goto out; /* skip atime */
1201 size = i_size_read(inode);
1202 if (pos < size) {
1203 retval = generic_file_direct_IO(READ, iocb,
1204 iov, pos, nr_segs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 if (retval > 0)
1206 *ppos = pos + retval;
1207 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001208 if (likely(retval != 0)) {
Steven Whitehouse3f1a9aa2006-09-27 14:52:48 -04001209 file_accessed(filp);
Steven Whitehousea9e5f4d2006-07-25 17:24:12 -04001210 goto out;
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001211 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 }
1213
1214 retval = 0;
1215 if (count) {
1216 for (seg = 0; seg < nr_segs; seg++) {
1217 read_descriptor_t desc;
1218
1219 desc.written = 0;
1220 desc.arg.buf = iov[seg].iov_base;
1221 desc.count = iov[seg].iov_len;
1222 if (desc.count == 0)
1223 continue;
1224 desc.error = 0;
1225 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1226 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001227 if (desc.error) {
1228 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 break;
1230 }
akpm@linux-foundation.orgc44939e2007-07-15 23:38:25 -07001231 if (desc.count > 0)
1232 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233 }
1234 }
1235out:
1236 return retval;
1237}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238EXPORT_SYMBOL(generic_file_aio_read);
1239
Linus Torvalds1da177e2005-04-16 15:20:36 -07001240static ssize_t
1241do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001242 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243{
1244 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1245 return -EINVAL;
1246
1247 force_page_cache_readahead(mapping, filp, index,
1248 max_sane_readahead(nr));
1249 return 0;
1250}
1251
1252asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1253{
1254 ssize_t ret;
1255 struct file *file;
1256
1257 ret = -EBADF;
1258 file = fget(fd);
1259 if (file) {
1260 if (file->f_mode & FMODE_READ) {
1261 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001262 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1263 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 unsigned long len = end - start + 1;
1265 ret = do_readahead(mapping, file, start, len);
1266 }
1267 fput(file);
1268 }
1269 return ret;
1270}
1271
1272#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001273/**
1274 * page_cache_read - adds requested page to the page cache if not already there
1275 * @file: file to read
1276 * @offset: page index
1277 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 * This adds the requested page to the page cache if it isn't already there,
1279 * and schedules an I/O to read in its contents from disk.
1280 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001281static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282{
1283 struct address_space *mapping = file->f_mapping;
1284 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001285 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286
Zach Brown994fc28c2005-12-15 14:28:17 -08001287 do {
1288 page = page_cache_alloc_cold(mapping);
1289 if (!page)
1290 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291
Zach Brown994fc28c2005-12-15 14:28:17 -08001292 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1293 if (ret == 0)
1294 ret = mapping->a_ops->readpage(file, page);
1295 else if (ret == -EEXIST)
1296 ret = 0; /* losing race to add is OK */
1297
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299
Zach Brown994fc28c2005-12-15 14:28:17 -08001300 } while (ret == AOP_TRUNCATED_PAGE);
1301
1302 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303}
1304
1305#define MMAP_LOTSAMISS (100)
1306
Randy Dunlap485bb992006-06-23 02:03:49 -07001307/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001308 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001309 * @vma: vma in which the fault was taken
1310 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001311 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001312 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313 * mapped memory region to read in file data during a page fault.
1314 *
1315 * The goto's are kind of ugly, but this streamlines the normal case of having
1316 * it in the page cache, and handles the special cases reasonably without
1317 * having a lot of duplicated code.
1318 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001319int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320{
1321 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001322 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323 struct address_space *mapping = file->f_mapping;
1324 struct file_ra_state *ra = &file->f_ra;
1325 struct inode *inode = mapping->host;
1326 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001327 pgoff_t size;
Nick Piggin54cb8822007-07-19 01:46:59 -07001328 int did_readaround = 0;
Nick Piggin83c54072007-07-19 01:47:05 -07001329 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001332 if (vmf->pgoff >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001333 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334
1335 /* If we don't want any read-ahead, don't bother */
Nick Piggin54cb8822007-07-19 01:46:59 -07001336 if (VM_RandomReadHint(vma))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001337 goto no_cached_page;
1338
1339 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 * Do we have something in the page cache already?
1341 */
1342retry_find:
Nick Piggind0217ac2007-07-19 01:47:03 -07001343 page = find_lock_page(mapping, vmf->pgoff);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001344 /*
1345 * For sequential accesses, we use the generic readahead logic.
1346 */
1347 if (VM_SequentialReadHint(vma)) {
1348 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001349 page_cache_sync_readahead(mapping, ra, file,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001350 vmf->pgoff, 1);
1351 page = find_lock_page(mapping, vmf->pgoff);
1352 if (!page)
1353 goto no_cached_page;
1354 }
1355 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001356 page_cache_async_readahead(mapping, ra, file, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001357 vmf->pgoff, 1);
1358 }
1359 }
1360
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 if (!page) {
1362 unsigned long ra_pages;
1363
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 ra->mmap_miss++;
1365
1366 /*
1367 * Do we miss much more than hit in this file? If so,
1368 * stop bothering with read-ahead. It will only hurt.
1369 */
Fengguang Wu0bb7ba62007-10-16 01:24:32 -07001370 if (ra->mmap_miss > MMAP_LOTSAMISS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 goto no_cached_page;
1372
1373 /*
1374 * To keep the pgmajfault counter straight, we need to
1375 * check did_readaround, as this is an inner loop.
1376 */
1377 if (!did_readaround) {
Nick Piggind0217ac2007-07-19 01:47:03 -07001378 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001379 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 }
1381 did_readaround = 1;
1382 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1383 if (ra_pages) {
1384 pgoff_t start = 0;
1385
Nick Piggind0217ac2007-07-19 01:47:03 -07001386 if (vmf->pgoff > ra_pages / 2)
1387 start = vmf->pgoff - ra_pages / 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388 do_page_cache_readahead(mapping, file, start, ra_pages);
1389 }
Nick Piggind0217ac2007-07-19 01:47:03 -07001390 page = find_lock_page(mapping, vmf->pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 if (!page)
1392 goto no_cached_page;
1393 }
1394
1395 if (!did_readaround)
Fengguang Wu0bb7ba62007-10-16 01:24:32 -07001396 ra->mmap_miss--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397
1398 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001399 * We have a locked page in the page cache, now we need to check
1400 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 */
Nick Piggind00806b2007-07-19 01:46:57 -07001402 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 goto page_not_uptodate;
1404
Nick Piggind00806b2007-07-19 01:46:57 -07001405 /* Must recheck i_size under page lock */
1406 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001407 if (unlikely(vmf->pgoff >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001408 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001409 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001410 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001411 }
1412
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 /*
1414 * Found the page and have a reference on it.
1415 */
1416 mark_page_accessed(page);
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001417 ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001418 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001419 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421no_cached_page:
1422 /*
1423 * We're only likely to ever get here if MADV_RANDOM is in
1424 * effect.
1425 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001426 error = page_cache_read(file, vmf->pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427
1428 /*
1429 * The page we want has now been added to the page cache.
1430 * In the unlikely event that someone removed it in the
1431 * meantime, we'll just come back here and read it again.
1432 */
1433 if (error >= 0)
1434 goto retry_find;
1435
1436 /*
1437 * An error return from page_cache_read can result if the
1438 * system is low on memory, or a problem occurs while trying
1439 * to schedule I/O.
1440 */
1441 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001442 return VM_FAULT_OOM;
1443 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444
1445page_not_uptodate:
Nick Piggind00806b2007-07-19 01:46:57 -07001446 /* IO error path */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 if (!did_readaround) {
Nick Piggind0217ac2007-07-19 01:47:03 -07001448 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001449 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451
1452 /*
1453 * Umm, take care of errors if the page isn't up-to-date.
1454 * Try to re-read it _once_. We do this synchronously,
1455 * because there really aren't any performance issues here
1456 * and we need to check for errors.
1457 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001459 error = mapping->a_ops->readpage(file, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001461
1462 if (!error || error == AOP_TRUNCATED_PAGE)
1463 goto retry_find;
1464
1465 /* Things didn't work out. Return zero to tell the mm layer so. */
1466 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001467 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001468}
1469EXPORT_SYMBOL(filemap_fault);
1470
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001472 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473};
1474
1475/* This is used for a general mmap of a disk file */
1476
1477int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1478{
1479 struct address_space *mapping = file->f_mapping;
1480
1481 if (!mapping->a_ops->readpage)
1482 return -ENOEXEC;
1483 file_accessed(file);
1484 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001485 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 return 0;
1487}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488
1489/*
1490 * This is for filesystems which do not implement ->writepage.
1491 */
1492int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1493{
1494 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1495 return -EINVAL;
1496 return generic_file_mmap(file, vma);
1497}
1498#else
1499int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1500{
1501 return -ENOSYS;
1502}
1503int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1504{
1505 return -ENOSYS;
1506}
1507#endif /* CONFIG_MMU */
1508
1509EXPORT_SYMBOL(generic_file_mmap);
1510EXPORT_SYMBOL(generic_file_readonly_mmap);
1511
Nick Piggin6fe69002007-05-06 14:49:04 -07001512static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001513 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514 int (*filler)(void *,struct page*),
1515 void *data)
1516{
Nick Piggineb2be182007-10-16 01:24:57 -07001517 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001518 int err;
1519repeat:
1520 page = find_get_page(mapping, index);
1521 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -07001522 page = page_cache_alloc_cold(mapping);
1523 if (!page)
1524 return ERR_PTR(-ENOMEM);
1525 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1526 if (unlikely(err)) {
1527 page_cache_release(page);
1528 if (err == -EEXIST)
1529 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 return ERR_PTR(err);
1532 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 err = filler(data, page);
1534 if (err < 0) {
1535 page_cache_release(page);
1536 page = ERR_PTR(err);
1537 }
1538 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 return page;
1540}
1541
Nick Piggin6fe69002007-05-06 14:49:04 -07001542/*
1543 * Same as read_cache_page, but don't wait for page to become unlocked
1544 * after submitting it to the filler.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 */
Nick Piggin6fe69002007-05-06 14:49:04 -07001546struct page *read_cache_page_async(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001547 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 int (*filler)(void *,struct page*),
1549 void *data)
1550{
1551 struct page *page;
1552 int err;
1553
1554retry:
1555 page = __read_cache_page(mapping, index, filler, data);
1556 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001557 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558 if (PageUptodate(page))
1559 goto out;
1560
1561 lock_page(page);
1562 if (!page->mapping) {
1563 unlock_page(page);
1564 page_cache_release(page);
1565 goto retry;
1566 }
1567 if (PageUptodate(page)) {
1568 unlock_page(page);
1569 goto out;
1570 }
1571 err = filler(data, page);
1572 if (err < 0) {
1573 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001574 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575 }
David Howellsc855ff32007-05-09 13:42:20 +01001576out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001577 mark_page_accessed(page);
1578 return page;
1579}
1580EXPORT_SYMBOL(read_cache_page_async);
1581
1582/**
1583 * read_cache_page - read into page cache, fill it if needed
1584 * @mapping: the page's address_space
1585 * @index: the page index
1586 * @filler: function to perform the read
1587 * @data: destination for read data
1588 *
1589 * Read into the page cache. If a page already exists, and PageUptodate() is
1590 * not set, try to fill the page then wait for it to become unlocked.
1591 *
1592 * If the page does not get brought uptodate, return -EIO.
1593 */
1594struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001595 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001596 int (*filler)(void *,struct page*),
1597 void *data)
1598{
1599 struct page *page;
1600
1601 page = read_cache_page_async(mapping, index, filler, data);
1602 if (IS_ERR(page))
1603 goto out;
1604 wait_on_page_locked(page);
1605 if (!PageUptodate(page)) {
1606 page_cache_release(page);
1607 page = ERR_PTR(-EIO);
1608 }
1609 out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610 return page;
1611}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612EXPORT_SYMBOL(read_cache_page);
1613
1614/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615 * The logic we want is
1616 *
1617 * if suid or (sgid and xgrp)
1618 * remove privs
1619 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001620int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001621{
1622 mode_t mode = dentry->d_inode->i_mode;
1623 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624
1625 /* suid always must be killed */
1626 if (unlikely(mode & S_ISUID))
1627 kill = ATTR_KILL_SUID;
1628
1629 /*
1630 * sgid without any exec bits is just a mandatory locking mark; leave
1631 * it alone. If some exec bits are set, it's a real sgid; kill it.
1632 */
1633 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1634 kill |= ATTR_KILL_SGID;
1635
Jens Axboe01de85e2006-10-17 19:50:36 +02001636 if (unlikely(kill && !capable(CAP_FSETID)))
1637 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638
Jens Axboe01de85e2006-10-17 19:50:36 +02001639 return 0;
1640}
Mark Fashehd23a1472006-10-17 17:05:18 -07001641EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001642
1643int __remove_suid(struct dentry *dentry, int kill)
1644{
1645 struct iattr newattrs;
1646
1647 newattrs.ia_valid = ATTR_FORCE | kill;
1648 return notify_change(dentry, &newattrs);
1649}
1650
1651int remove_suid(struct dentry *dentry)
1652{
Serge E. Hallynb5376772007-10-16 23:31:36 -07001653 int killsuid = should_remove_suid(dentry);
1654 int killpriv = security_inode_need_killpriv(dentry);
1655 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001656
Serge E. Hallynb5376772007-10-16 23:31:36 -07001657 if (killpriv < 0)
1658 return killpriv;
1659 if (killpriv)
1660 error = security_inode_killpriv(dentry);
1661 if (!error && killsuid)
1662 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001663
Serge E. Hallynb5376772007-10-16 23:31:36 -07001664 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665}
1666EXPORT_SYMBOL(remove_suid);
1667
Nick Piggin2f718ff2007-10-16 01:24:59 -07001668static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669 const struct iovec *iov, size_t base, size_t bytes)
1670{
1671 size_t copied = 0, left = 0;
1672
1673 while (bytes) {
1674 char __user *buf = iov->iov_base + base;
1675 int copy = min(bytes, iov->iov_len - base);
1676
1677 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001678 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001679 copied += copy;
1680 bytes -= copy;
1681 vaddr += copy;
1682 iov++;
1683
NeilBrown01408c42006-06-25 05:47:58 -07001684 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 }
1687 return copied - left;
1688}
1689
1690/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001691 * Copy as much as we can into the page and return the number of bytes which
1692 * were sucessfully copied. If a fault is encountered then return the number of
1693 * bytes which were copied.
1694 */
1695size_t iov_iter_copy_from_user_atomic(struct page *page,
1696 struct iov_iter *i, unsigned long offset, size_t bytes)
1697{
1698 char *kaddr;
1699 size_t copied;
1700
1701 BUG_ON(!in_atomic());
1702 kaddr = kmap_atomic(page, KM_USER0);
1703 if (likely(i->nr_segs == 1)) {
1704 int left;
1705 char __user *buf = i->iov->iov_base + i->iov_offset;
1706 left = __copy_from_user_inatomic_nocache(kaddr + offset,
1707 buf, bytes);
1708 copied = bytes - left;
1709 } else {
1710 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1711 i->iov, i->iov_offset, bytes);
1712 }
1713 kunmap_atomic(kaddr, KM_USER0);
1714
1715 return copied;
1716}
Nick Piggin89e10782007-10-16 01:25:07 -07001717EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001718
1719/*
1720 * This has the same sideeffects and return value as
1721 * iov_iter_copy_from_user_atomic().
1722 * The difference is that it attempts to resolve faults.
1723 * Page must not be locked.
1724 */
1725size_t iov_iter_copy_from_user(struct page *page,
1726 struct iov_iter *i, unsigned long offset, size_t bytes)
1727{
1728 char *kaddr;
1729 size_t copied;
1730
1731 kaddr = kmap(page);
1732 if (likely(i->nr_segs == 1)) {
1733 int left;
1734 char __user *buf = i->iov->iov_base + i->iov_offset;
1735 left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
1736 copied = bytes - left;
1737 } else {
1738 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1739 i->iov, i->iov_offset, bytes);
1740 }
1741 kunmap(page);
1742 return copied;
1743}
Nick Piggin89e10782007-10-16 01:25:07 -07001744EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001745
1746static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
1747{
1748 if (likely(i->nr_segs == 1)) {
1749 i->iov_offset += bytes;
1750 } else {
1751 const struct iovec *iov = i->iov;
1752 size_t base = i->iov_offset;
1753
Nick Piggin124d3b72008-02-02 15:01:17 +01001754 /*
1755 * The !iov->iov_len check ensures we skip over unlikely
1756 * zero-length segments.
1757 */
1758 while (bytes || !iov->iov_len) {
Nick Piggin2f718ff2007-10-16 01:24:59 -07001759 int copy = min(bytes, iov->iov_len - base);
1760
1761 bytes -= copy;
1762 base += copy;
1763 if (iov->iov_len == base) {
1764 iov++;
1765 base = 0;
1766 }
1767 }
1768 i->iov = iov;
1769 i->iov_offset = base;
1770 }
1771}
1772
1773void iov_iter_advance(struct iov_iter *i, size_t bytes)
1774{
1775 BUG_ON(i->count < bytes);
1776
1777 __iov_iter_advance_iov(i, bytes);
1778 i->count -= bytes;
1779}
Nick Piggin89e10782007-10-16 01:25:07 -07001780EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001781
Nick Pigginafddba42007-10-16 01:25:01 -07001782/*
1783 * Fault in the first iovec of the given iov_iter, to a maximum length
1784 * of bytes. Returns 0 on success, or non-zero if the memory could not be
1785 * accessed (ie. because it is an invalid address).
1786 *
1787 * writev-intensive code may want this to prefault several iovecs -- that
1788 * would be possible (callers must not rely on the fact that _only_ the
1789 * first iovec will be faulted with the current implementation).
1790 */
1791int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001792{
Nick Piggin2f718ff2007-10-16 01:24:59 -07001793 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07001794 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
1795 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001796}
Nick Piggin89e10782007-10-16 01:25:07 -07001797EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001798
1799/*
1800 * Return the count of just the current iov_iter segment.
1801 */
1802size_t iov_iter_single_seg_count(struct iov_iter *i)
1803{
1804 const struct iovec *iov = i->iov;
1805 if (i->nr_segs == 1)
1806 return i->count;
1807 else
1808 return min(i->count, iov->iov_len - i->iov_offset);
1809}
Nick Piggin89e10782007-10-16 01:25:07 -07001810EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001811
1812/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813 * Performs necessary checks before doing a write
1814 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001815 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 * Returns appropriate error code that caller should return or
1817 * zero in case that write should be allowed.
1818 */
1819inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1820{
1821 struct inode *inode = file->f_mapping->host;
1822 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1823
1824 if (unlikely(*pos < 0))
1825 return -EINVAL;
1826
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 if (!isblk) {
1828 /* FIXME: this is for backwards compatibility with 2.4 */
1829 if (file->f_flags & O_APPEND)
1830 *pos = i_size_read(inode);
1831
1832 if (limit != RLIM_INFINITY) {
1833 if (*pos >= limit) {
1834 send_sig(SIGXFSZ, current, 0);
1835 return -EFBIG;
1836 }
1837 if (*count > limit - (typeof(limit))*pos) {
1838 *count = limit - (typeof(limit))*pos;
1839 }
1840 }
1841 }
1842
1843 /*
1844 * LFS rule
1845 */
1846 if (unlikely(*pos + *count > MAX_NON_LFS &&
1847 !(file->f_flags & O_LARGEFILE))) {
1848 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 return -EFBIG;
1850 }
1851 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1852 *count = MAX_NON_LFS - (unsigned long)*pos;
1853 }
1854 }
1855
1856 /*
1857 * Are we about to exceed the fs block limit ?
1858 *
1859 * If we have written data it becomes a short write. If we have
1860 * exceeded without writing data we send a signal and return EFBIG.
1861 * Linus frestrict idea will clean these up nicely..
1862 */
1863 if (likely(!isblk)) {
1864 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1865 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 return -EFBIG;
1867 }
1868 /* zero-length writes at ->s_maxbytes are OK */
1869 }
1870
1871 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1872 *count = inode->i_sb->s_maxbytes - *pos;
1873 } else {
David Howells93614012006-09-30 20:45:40 +02001874#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 loff_t isize;
1876 if (bdev_read_only(I_BDEV(inode)))
1877 return -EPERM;
1878 isize = i_size_read(inode);
1879 if (*pos >= isize) {
1880 if (*count || *pos > isize)
1881 return -ENOSPC;
1882 }
1883
1884 if (*pos + *count > isize)
1885 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02001886#else
1887 return -EPERM;
1888#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889 }
1890 return 0;
1891}
1892EXPORT_SYMBOL(generic_write_checks);
1893
Nick Pigginafddba42007-10-16 01:25:01 -07001894int pagecache_write_begin(struct file *file, struct address_space *mapping,
1895 loff_t pos, unsigned len, unsigned flags,
1896 struct page **pagep, void **fsdata)
1897{
1898 const struct address_space_operations *aops = mapping->a_ops;
1899
1900 if (aops->write_begin) {
1901 return aops->write_begin(file, mapping, pos, len, flags,
1902 pagep, fsdata);
1903 } else {
1904 int ret;
1905 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1906 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1907 struct inode *inode = mapping->host;
1908 struct page *page;
1909again:
1910 page = __grab_cache_page(mapping, index);
1911 *pagep = page;
1912 if (!page)
1913 return -ENOMEM;
1914
1915 if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
1916 /*
1917 * There is no way to resolve a short write situation
1918 * for a !Uptodate page (except by double copying in
1919 * the caller done by generic_perform_write_2copy).
1920 *
1921 * Instead, we have to bring it uptodate here.
1922 */
1923 ret = aops->readpage(file, page);
1924 page_cache_release(page);
1925 if (ret) {
1926 if (ret == AOP_TRUNCATED_PAGE)
1927 goto again;
1928 return ret;
1929 }
1930 goto again;
1931 }
1932
1933 ret = aops->prepare_write(file, page, offset, offset+len);
1934 if (ret) {
Nick Piggin55144762007-10-16 01:25:26 -07001935 unlock_page(page);
Nick Pigginafddba42007-10-16 01:25:01 -07001936 page_cache_release(page);
1937 if (pos + len > inode->i_size)
1938 vmtruncate(inode, inode->i_size);
Nick Pigginafddba42007-10-16 01:25:01 -07001939 }
1940 return ret;
1941 }
1942}
1943EXPORT_SYMBOL(pagecache_write_begin);
1944
1945int pagecache_write_end(struct file *file, struct address_space *mapping,
1946 loff_t pos, unsigned len, unsigned copied,
1947 struct page *page, void *fsdata)
1948{
1949 const struct address_space_operations *aops = mapping->a_ops;
1950 int ret;
1951
1952 if (aops->write_end) {
1953 mark_page_accessed(page);
1954 ret = aops->write_end(file, mapping, pos, len, copied,
1955 page, fsdata);
1956 } else {
1957 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
1958 struct inode *inode = mapping->host;
1959
1960 flush_dcache_page(page);
1961 ret = aops->commit_write(file, page, offset, offset+len);
1962 unlock_page(page);
1963 mark_page_accessed(page);
1964 page_cache_release(page);
Nick Pigginafddba42007-10-16 01:25:01 -07001965
1966 if (ret < 0) {
1967 if (pos + len > inode->i_size)
1968 vmtruncate(inode, inode->i_size);
1969 } else if (ret > 0)
1970 ret = min_t(size_t, copied, ret);
1971 else
1972 ret = copied;
1973 }
1974
1975 return ret;
1976}
1977EXPORT_SYMBOL(pagecache_write_end);
1978
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979ssize_t
1980generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
1981 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
1982 size_t count, size_t ocount)
1983{
1984 struct file *file = iocb->ki_filp;
1985 struct address_space *mapping = file->f_mapping;
1986 struct inode *inode = mapping->host;
1987 ssize_t written;
1988
1989 if (count != ocount)
1990 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
1991
1992 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
1993 if (written > 0) {
1994 loff_t end = pos + written;
1995 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
1996 i_size_write(inode, end);
1997 mark_inode_dirty(inode);
1998 }
1999 *ppos = end;
2000 }
2001
2002 /*
2003 * Sync the fs metadata but not the minor inode changes and
2004 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002005 * i_mutex is held, which protects generic_osync_inode() from
Zach Brown8459d862006-12-10 02:21:05 -08002006 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 */
Zach Brown8459d862006-12-10 02:21:05 -08002008 if ((written >= 0 || written == -EIOCBQUEUED) &&
2009 ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07002010 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2011 if (err < 0)
2012 written = err;
2013 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014 return written;
2015}
2016EXPORT_SYMBOL(generic_file_direct_write);
2017
Nick Piggineb2be182007-10-16 01:24:57 -07002018/*
2019 * Find or create a page at the given pagecache position. Return the locked
2020 * page. This function is specifically for buffered writes.
2021 */
Nick Pigginafddba42007-10-16 01:25:01 -07002022struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index)
Nick Piggineb2be182007-10-16 01:24:57 -07002023{
2024 int status;
2025 struct page *page;
2026repeat:
2027 page = find_lock_page(mapping, index);
2028 if (likely(page))
2029 return page;
2030
2031 page = page_cache_alloc(mapping);
2032 if (!page)
2033 return NULL;
2034 status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
2035 if (unlikely(status)) {
2036 page_cache_release(page);
2037 if (status == -EEXIST)
2038 goto repeat;
2039 return NULL;
2040 }
2041 return page;
2042}
Nick Pigginafddba42007-10-16 01:25:01 -07002043EXPORT_SYMBOL(__grab_cache_page);
Nick Piggineb2be182007-10-16 01:24:57 -07002044
Nick Pigginafddba42007-10-16 01:25:01 -07002045static ssize_t generic_perform_write_2copy(struct file *file,
2046 struct iov_iter *i, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047{
Andrew Mortonae374612007-10-16 01:24:55 -07002048 struct address_space *mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002049 const struct address_space_operations *a_ops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002050 struct inode *inode = mapping->host;
2051 long status = 0;
2052 ssize_t written = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053
2054 do {
Nick Piggin08291422007-10-16 01:24:59 -07002055 struct page *src_page;
Nick Piggineb2be182007-10-16 01:24:57 -07002056 struct page *page;
Andrew Mortonae374612007-10-16 01:24:55 -07002057 pgoff_t index; /* Pagecache index for current page */
2058 unsigned long offset; /* Offset into pagecache page */
Nick Piggin08291422007-10-16 01:24:59 -07002059 unsigned long bytes; /* Bytes to write to page */
Andrew Mortonae374612007-10-16 01:24:55 -07002060 size_t copied; /* Bytes copied from user */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061
Andrew Mortonae374612007-10-16 01:24:55 -07002062 offset = (pos & (PAGE_CACHE_SIZE - 1));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 index = pos >> PAGE_CACHE_SHIFT;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002064 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
Nick Pigginafddba42007-10-16 01:25:01 -07002065 iov_iter_count(i));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066
Nick Piggin08291422007-10-16 01:24:59 -07002067 /*
2068 * a non-NULL src_page indicates that we're doing the
2069 * copy via get_user_pages and kmap.
2070 */
2071 src_page = NULL;
Andrew Mortonae374612007-10-16 01:24:55 -07002072
Nick Piggin41cb8ac2007-10-16 01:24:53 -07002073 /*
2074 * Bring in the user page that we will copy from _first_.
2075 * Otherwise there's a nasty deadlock on copying from the
2076 * same page as we're writing to, without it being marked
2077 * up-to-date.
Nick Piggin08291422007-10-16 01:24:59 -07002078 *
2079 * Not only is this an optimisation, but it is also required
2080 * to check that the address is actually valid, when atomic
2081 * usercopies are used, below.
Nick Piggin41cb8ac2007-10-16 01:24:53 -07002082 */
Nick Pigginafddba42007-10-16 01:25:01 -07002083 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
Nick Piggin08291422007-10-16 01:24:59 -07002084 status = -EFAULT;
2085 break;
2086 }
Nick Piggineb2be182007-10-16 01:24:57 -07002087
2088 page = __grab_cache_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 if (!page) {
2090 status = -ENOMEM;
2091 break;
2092 }
2093
Nick Piggin08291422007-10-16 01:24:59 -07002094 /*
2095 * non-uptodate pages cannot cope with short copies, and we
2096 * cannot take a pagefault with the destination page locked.
2097 * So pin the source page to copy it.
2098 */
Nick Piggin674b8922007-10-16 01:25:03 -07002099 if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
Nick Piggin08291422007-10-16 01:24:59 -07002100 unlock_page(page);
2101
2102 src_page = alloc_page(GFP_KERNEL);
2103 if (!src_page) {
2104 page_cache_release(page);
2105 status = -ENOMEM;
2106 break;
2107 }
2108
2109 /*
2110 * Cannot get_user_pages with a page locked for the
2111 * same reason as we can't take a page fault with a
2112 * page locked (as explained below).
2113 */
Nick Pigginafddba42007-10-16 01:25:01 -07002114 copied = iov_iter_copy_from_user(src_page, i,
Nick Piggin2f718ff2007-10-16 01:24:59 -07002115 offset, bytes);
Nick Piggin08291422007-10-16 01:24:59 -07002116 if (unlikely(copied == 0)) {
2117 status = -EFAULT;
2118 page_cache_release(page);
2119 page_cache_release(src_page);
2120 break;
2121 }
2122 bytes = copied;
2123
2124 lock_page(page);
2125 /*
2126 * Can't handle the page going uptodate here, because
2127 * that means we would use non-atomic usercopies, which
2128 * zero out the tail of the page, which can cause
2129 * zeroes to become transiently visible. We could just
2130 * use a non-zeroing copy, but the APIs aren't too
2131 * consistent.
2132 */
2133 if (unlikely(!page->mapping || PageUptodate(page))) {
2134 unlock_page(page);
2135 page_cache_release(page);
2136 page_cache_release(src_page);
2137 continue;
2138 }
Nick Piggin08291422007-10-16 01:24:59 -07002139 }
2140
Linus Torvalds1da177e2005-04-16 15:20:36 -07002141 status = a_ops->prepare_write(file, page, offset, offset+bytes);
Nick Piggin64649a52007-10-16 01:24:56 -07002142 if (unlikely(status))
2143 goto fs_write_aop_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08002144
Nick Piggin08291422007-10-16 01:24:59 -07002145 if (!src_page) {
2146 /*
2147 * Must not enter the pagefault handler here, because
2148 * we hold the page lock, so we might recursively
2149 * deadlock on the same lock, or get an ABBA deadlock
2150 * against a different lock, or against the mmap_sem
2151 * (which nests outside the page lock). So increment
2152 * preempt count, and use _atomic usercopies.
2153 *
2154 * The page is uptodate so we are OK to encounter a
2155 * short copy: if unmodified parts of the page are
2156 * marked dirty and written out to disk, it doesn't
2157 * really matter.
2158 */
2159 pagefault_disable();
Nick Pigginafddba42007-10-16 01:25:01 -07002160 copied = iov_iter_copy_from_user_atomic(page, i,
Nick Piggin2f718ff2007-10-16 01:24:59 -07002161 offset, bytes);
Nick Piggin08291422007-10-16 01:24:59 -07002162 pagefault_enable();
2163 } else {
2164 void *src, *dst;
2165 src = kmap_atomic(src_page, KM_USER0);
2166 dst = kmap_atomic(page, KM_USER1);
2167 memcpy(dst + offset, src + offset, bytes);
2168 kunmap_atomic(dst, KM_USER1);
2169 kunmap_atomic(src, KM_USER0);
2170 copied = bytes;
2171 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 flush_dcache_page(page);
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002173
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 status = a_ops->commit_write(file, page, offset, offset+bytes);
Nick Piggin55144762007-10-16 01:25:26 -07002175 if (unlikely(status < 0))
Nick Piggin64649a52007-10-16 01:24:56 -07002176 goto fs_write_aop_error;
Nick Piggin64649a52007-10-16 01:24:56 -07002177 if (unlikely(status > 0)) /* filesystem did partial write */
Nick Piggin08291422007-10-16 01:24:59 -07002178 copied = min_t(size_t, copied, status);
2179
2180 unlock_page(page);
2181 mark_page_accessed(page);
2182 page_cache_release(page);
2183 if (src_page)
2184 page_cache_release(src_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185
Nick Pigginafddba42007-10-16 01:25:01 -07002186 iov_iter_advance(i, copied);
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002187 pos += copied;
Nick Pigginafddba42007-10-16 01:25:01 -07002188 written += copied;
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002189
Linus Torvalds1da177e2005-04-16 15:20:36 -07002190 balance_dirty_pages_ratelimited(mapping);
2191 cond_resched();
Nick Piggin64649a52007-10-16 01:24:56 -07002192 continue;
2193
2194fs_write_aop_error:
Nick Piggin55144762007-10-16 01:25:26 -07002195 unlock_page(page);
Nick Piggin64649a52007-10-16 01:24:56 -07002196 page_cache_release(page);
Nick Piggin08291422007-10-16 01:24:59 -07002197 if (src_page)
2198 page_cache_release(src_page);
Nick Piggin64649a52007-10-16 01:24:56 -07002199
2200 /*
2201 * prepare_write() may have instantiated a few blocks
2202 * outside i_size. Trim these off again. Don't need
2203 * i_size_read because we hold i_mutex.
2204 */
2205 if (pos + bytes > inode->i_size)
2206 vmtruncate(inode, inode->i_size);
Nick Piggin55144762007-10-16 01:25:26 -07002207 break;
Nick Pigginafddba42007-10-16 01:25:01 -07002208 } while (iov_iter_count(i));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209
Nick Pigginafddba42007-10-16 01:25:01 -07002210 return written ? written : status;
2211}
2212
2213static ssize_t generic_perform_write(struct file *file,
2214 struct iov_iter *i, loff_t pos)
2215{
2216 struct address_space *mapping = file->f_mapping;
2217 const struct address_space_operations *a_ops = mapping->a_ops;
2218 long status = 0;
2219 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002220 unsigned int flags = 0;
2221
2222 /*
2223 * Copies from kernel address space cannot fail (NFSD is a big user).
2224 */
2225 if (segment_eq(get_fs(), KERNEL_DS))
2226 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002227
2228 do {
2229 struct page *page;
2230 pgoff_t index; /* Pagecache index for current page */
2231 unsigned long offset; /* Offset into pagecache page */
2232 unsigned long bytes; /* Bytes to write to page */
2233 size_t copied; /* Bytes copied from user */
2234 void *fsdata;
2235
2236 offset = (pos & (PAGE_CACHE_SIZE - 1));
2237 index = pos >> PAGE_CACHE_SHIFT;
2238 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2239 iov_iter_count(i));
2240
2241again:
2242
2243 /*
2244 * Bring in the user page that we will copy from _first_.
2245 * Otherwise there's a nasty deadlock on copying from the
2246 * same page as we're writing to, without it being marked
2247 * up-to-date.
2248 *
2249 * Not only is this an optimisation, but it is also required
2250 * to check that the address is actually valid, when atomic
2251 * usercopies are used, below.
2252 */
2253 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2254 status = -EFAULT;
2255 break;
2256 }
2257
Nick Piggin674b8922007-10-16 01:25:03 -07002258 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002259 &page, &fsdata);
2260 if (unlikely(status))
2261 break;
2262
2263 pagefault_disable();
2264 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2265 pagefault_enable();
2266 flush_dcache_page(page);
2267
2268 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2269 page, fsdata);
2270 if (unlikely(status < 0))
2271 break;
2272 copied = status;
2273
2274 cond_resched();
2275
Nick Piggin124d3b72008-02-02 15:01:17 +01002276 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002277 if (unlikely(copied == 0)) {
2278 /*
2279 * If we were unable to copy any data at all, we must
2280 * fall back to a single segment length write.
2281 *
2282 * If we didn't fallback here, we could livelock
2283 * because not all segments in the iov can be copied at
2284 * once without a pagefault.
2285 */
2286 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2287 iov_iter_single_seg_count(i));
2288 goto again;
2289 }
Nick Pigginafddba42007-10-16 01:25:01 -07002290 pos += copied;
2291 written += copied;
2292
2293 balance_dirty_pages_ratelimited(mapping);
2294
2295 } while (iov_iter_count(i));
2296
2297 return written ? written : status;
2298}
2299
2300ssize_t
2301generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2302 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2303 size_t count, ssize_t written)
2304{
2305 struct file *file = iocb->ki_filp;
2306 struct address_space *mapping = file->f_mapping;
2307 const struct address_space_operations *a_ops = mapping->a_ops;
2308 struct inode *inode = mapping->host;
2309 ssize_t status;
2310 struct iov_iter i;
2311
2312 iov_iter_init(&i, iov, nr_segs, count, written);
2313 if (a_ops->write_begin)
2314 status = generic_perform_write(file, &i, pos);
2315 else
2316 status = generic_perform_write_2copy(file, &i, pos);
2317
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002319 written += status;
2320 *ppos = pos + status;
2321
2322 /*
2323 * For now, when the user asks for O_SYNC, we'll actually give
2324 * O_DSYNC
2325 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2327 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2328 status = generic_osync_inode(inode, mapping,
2329 OSYNC_METADATA|OSYNC_DATA);
2330 }
2331 }
2332
2333 /*
2334 * If we get here for O_DIRECT writes then we must have fallen through
2335 * to buffered writes (block instantiation inside i_size). So we sync
2336 * the file data here, to try to honour O_DIRECT expectations.
2337 */
2338 if (unlikely(file->f_flags & O_DIRECT) && written)
2339 status = filemap_write_and_wait(mapping);
2340
Linus Torvalds1da177e2005-04-16 15:20:36 -07002341 return written ? written : status;
2342}
2343EXPORT_SYMBOL(generic_file_buffered_write);
2344
Adrian Bunk5ce78522005-09-10 00:26:28 -07002345static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2347 unsigned long nr_segs, loff_t *ppos)
2348{
2349 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002350 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351 size_t ocount; /* original count */
2352 size_t count; /* after file limit checks */
2353 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354 loff_t pos;
2355 ssize_t written;
2356 ssize_t err;
2357
2358 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002359 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2360 if (err)
2361 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002362
2363 count = ocount;
2364 pos = *ppos;
2365
2366 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2367
2368 /* We can write back this queue in page reclaim */
2369 current->backing_dev_info = mapping->backing_dev_info;
2370 written = 0;
2371
2372 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2373 if (err)
2374 goto out;
2375
2376 if (count == 0)
2377 goto out;
2378
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002379 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002380 if (err)
2381 goto out;
2382
Christoph Hellwig870f4812006-01-09 20:52:01 -08002383 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384
2385 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2386 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002387 loff_t endbyte;
2388 ssize_t written_buffered;
2389
2390 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2391 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002392 if (written < 0 || written == count)
2393 goto out;
2394 /*
2395 * direct-io write to a hole: fall through to buffered I/O
2396 * for completing the rest of the request.
2397 */
2398 pos += written;
2399 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002400 written_buffered = generic_file_buffered_write(iocb, iov,
2401 nr_segs, pos, ppos, count,
2402 written);
2403 /*
2404 * If generic_file_buffered_write() retuned a synchronous error
2405 * then we want to return the number of bytes which were
2406 * direct-written, or the error code if that was zero. Note
2407 * that this differs from normal direct-io semantics, which
2408 * will return -EFOO even if some bytes were written.
2409 */
2410 if (written_buffered < 0) {
2411 err = written_buffered;
2412 goto out;
2413 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002415 /*
2416 * We need to ensure that the page cache pages are written to
2417 * disk and invalidated to preserve the expected O_DIRECT
2418 * semantics.
2419 */
2420 endbyte = pos + written_buffered - written - 1;
Mark Fashehef51c972007-05-08 00:27:10 -07002421 err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
2422 SYNC_FILE_RANGE_WAIT_BEFORE|
2423 SYNC_FILE_RANGE_WRITE|
2424 SYNC_FILE_RANGE_WAIT_AFTER);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002425 if (err == 0) {
2426 written = written_buffered;
2427 invalidate_mapping_pages(mapping,
2428 pos >> PAGE_CACHE_SHIFT,
2429 endbyte >> PAGE_CACHE_SHIFT);
2430 } else {
2431 /*
2432 * We don't know how much we wrote, so just return
2433 * the number of bytes which were direct-written
2434 */
2435 }
2436 } else {
2437 written = generic_file_buffered_write(iocb, iov, nr_segs,
2438 pos, ppos, count, written);
2439 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440out:
2441 current->backing_dev_info = NULL;
2442 return written ? written : err;
2443}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002444
Badari Pulavarty027445c2006-09-30 23:28:46 -07002445ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2446 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002447{
2448 struct file *file = iocb->ki_filp;
2449 struct address_space *mapping = file->f_mapping;
2450 struct inode *inode = mapping->host;
2451 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002452
Badari Pulavarty027445c2006-09-30 23:28:46 -07002453 BUG_ON(iocb->ki_pos != pos);
2454
2455 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2456 &iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457
2458 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Badari Pulavarty027445c2006-09-30 23:28:46 -07002459 ssize_t err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002460
2461 err = sync_page_range_nolock(inode, mapping, pos, ret);
2462 if (err < 0)
2463 ret = err;
2464 }
2465 return ret;
2466}
Badari Pulavarty027445c2006-09-30 23:28:46 -07002467EXPORT_SYMBOL(generic_file_aio_write_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002468
Badari Pulavarty027445c2006-09-30 23:28:46 -07002469ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2470 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471{
2472 struct file *file = iocb->ki_filp;
2473 struct address_space *mapping = file->f_mapping;
2474 struct inode *inode = mapping->host;
2475 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002476
2477 BUG_ON(iocb->ki_pos != pos);
2478
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002479 mutex_lock(&inode->i_mutex);
Badari Pulavarty027445c2006-09-30 23:28:46 -07002480 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2481 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002482 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483
2484 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2485 ssize_t err;
2486
2487 err = sync_page_range(inode, mapping, pos, ret);
2488 if (err < 0)
2489 ret = err;
2490 }
2491 return ret;
2492}
2493EXPORT_SYMBOL(generic_file_aio_write);
2494
Linus Torvalds1da177e2005-04-16 15:20:36 -07002495/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002496 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497 * went wrong during pagecache shootdown.
2498 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002499static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2501 loff_t offset, unsigned long nr_segs)
2502{
2503 struct file *file = iocb->ki_filp;
2504 struct address_space *mapping = file->f_mapping;
2505 ssize_t retval;
Zach Brown65b82912007-03-16 13:38:11 -08002506 size_t write_len;
2507 pgoff_t end = 0; /* silence gcc */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002508
2509 /*
2510 * If it's a write, unmap all mmappings of the file up-front. This
2511 * will cause any pte dirty bits to be propagated into the pageframes
2512 * for the subsequent filemap_write_and_wait().
2513 */
2514 if (rw == WRITE) {
2515 write_len = iov_length(iov, nr_segs);
Zach Brown65b82912007-03-16 13:38:11 -08002516 end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002517 if (mapping_mapped(mapping))
2518 unmap_mapping_range(mapping, offset, write_len, 0);
2519 }
2520
2521 retval = filemap_write_and_wait(mapping);
Zach Brown65b82912007-03-16 13:38:11 -08002522 if (retval)
2523 goto out;
2524
2525 /*
2526 * After a write we want buffered reads to be sure to go to disk to get
2527 * the new data. We invalidate clean cached page from the region we're
2528 * about to write. We do this *before* the write so that we can return
2529 * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
2530 */
2531 if (rw == WRITE && mapping->nrpages) {
2532 retval = invalidate_inode_pages2_range(mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533 offset >> PAGE_CACHE_SHIFT, end);
Zach Brown65b82912007-03-16 13:38:11 -08002534 if (retval)
2535 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002536 }
Zach Brown65b82912007-03-16 13:38:11 -08002537
2538 retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
Zach Brown65b82912007-03-16 13:38:11 -08002539
2540 /*
2541 * Finally, try again to invalidate clean pages which might have been
Zach Brownbdb76ef2007-10-30 11:45:46 -07002542 * cached by non-direct readahead, or faulted in by get_user_pages()
2543 * if the source of the write was an mmap'ed region of the file
2544 * we're writing. Either one is a pretty crazy thing to do,
2545 * so we don't support it 100%. If this invalidation
2546 * fails, tough, the write still worked...
Zach Brown65b82912007-03-16 13:38:11 -08002547 */
2548 if (rw == WRITE && mapping->nrpages) {
Zach Brownbdb76ef2007-10-30 11:45:46 -07002549 invalidate_inode_pages2_range(mapping, offset >> PAGE_CACHE_SHIFT, end);
Zach Brown65b82912007-03-16 13:38:11 -08002550 }
2551out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552 return retval;
2553}
David Howellscf9a2ae2006-08-29 19:05:54 +01002554
2555/**
2556 * try_to_release_page() - release old fs-specific metadata on a page
2557 *
2558 * @page: the page which the kernel is trying to free
2559 * @gfp_mask: memory allocation flags (and I/O mode)
2560 *
2561 * The address_space is to try to release any data against the page
2562 * (presumably at page->private). If the release was successful, return `1'.
2563 * Otherwise return zero.
2564 *
2565 * The @gfp_mask argument specifies whether I/O may be performed to release
2566 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2567 *
2568 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2569 */
2570int try_to_release_page(struct page *page, gfp_t gfp_mask)
2571{
2572 struct address_space * const mapping = page->mapping;
2573
2574 BUG_ON(!PageLocked(page));
2575 if (PageWriteback(page))
2576 return 0;
2577
2578 if (mapping && mapping->a_ops->releasepage)
2579 return mapping->a_ops->releasepage(page, gfp_mask);
2580 return try_to_free_buffers(page);
2581}
2582
2583EXPORT_SYMBOL(try_to_release_page);