blob: edb1b0b5cc8dc64367eb9950378a9829a1e07241 [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>
28#include <linux/pagevec.h>
29#include <linux/blkdev.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
Paul Jackson44110fe2006-03-24 03:16:04 -080032#include <linux/cpuset.h>
Carsten Otteceffc072005-06-23 22:05:25 -070033#include "filemap.h"
Nick Piggin0f8053a2006-03-22 00:08:33 -080034#include "internal.h"
35
Linus Torvalds1da177e2005-04-16 15:20:36 -070036/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 * FIXME: remove all knowledge of the buffer layer from the core VM
38 */
39#include <linux/buffer_head.h> /* for generic_osync_inode */
40
Linus Torvalds1da177e2005-04-16 15:20:36 -070041#include <asm/mman.h>
42
Adrian Bunk5ce78522005-09-10 00:26:28 -070043static ssize_t
44generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
45 loff_t offset, unsigned long nr_segs);
46
Linus Torvalds1da177e2005-04-16 15:20:36 -070047/*
48 * Shared mappings implemented 30.11.1994. It's not fully working yet,
49 * though.
50 *
51 * Shared mappings now work. 15.8.1995 Bruno.
52 *
53 * finished 'unifying' the page and buffer cache and SMP-threaded the
54 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
55 *
56 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
57 */
58
59/*
60 * Lock ordering:
61 *
62 * ->i_mmap_lock (vmtruncate)
63 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070064 * ->swap_lock (exclusive_swap_page, others)
65 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080067 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070068 * ->i_mmap_lock (truncate->unmap_mapping_range)
69 *
70 * ->mmap_sem
71 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070072 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
74 *
75 * ->mmap_sem
76 * ->lock_page (access_process_vm)
77 *
Nick Piggin82591e62006-10-19 23:29:10 -070078 * ->i_mutex (generic_file_buffered_write)
79 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080081 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 * ->i_alloc_sem (various)
83 *
84 * ->inode_lock
85 * ->sb_lock (fs/fs-writeback.c)
86 * ->mapping->tree_lock (__sync_single_inode)
87 *
88 * ->i_mmap_lock
89 * ->anon_vma.lock (vma_adjust)
90 *
91 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070092 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070094 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070095 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 * ->private_lock (try_to_unmap_one)
97 * ->tree_lock (try_to_unmap_one)
98 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -080099 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 * ->private_lock (page_remove_rmap->set_page_dirty)
101 * ->tree_lock (page_remove_rmap->set_page_dirty)
102 * ->inode_lock (page_remove_rmap->set_page_dirty)
103 * ->inode_lock (zap_pte_range->set_page_dirty)
104 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
105 *
106 * ->task->proc_lock
107 * ->dcache_lock (proc_pid_lookup)
108 */
109
110/*
111 * Remove a page from the page cache and free it. Caller has to make
112 * sure the page is locked and that nobody else uses it - or that usage
113 * is safe. The caller must hold a write_lock on the mapping's tree_lock.
114 */
115void __remove_from_page_cache(struct page *page)
116{
117 struct address_space *mapping = page->mapping;
118
119 radix_tree_delete(&mapping->page_tree, page->index);
120 page->mapping = NULL;
121 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700122 __dec_zone_page_state(page, NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123}
124
125void remove_from_page_cache(struct page *page)
126{
127 struct address_space *mapping = page->mapping;
128
Matt Mackallcd7619d2005-05-01 08:59:01 -0700129 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130
131 write_lock_irq(&mapping->tree_lock);
132 __remove_from_page_cache(page);
133 write_unlock_irq(&mapping->tree_lock);
134}
135
136static int sync_page(void *word)
137{
138 struct address_space *mapping;
139 struct page *page;
140
Andi Kleen07808b72005-11-05 17:25:53 +0100141 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142
143 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700144 * page_mapping() is being called without PG_locked held.
145 * Some knowledge of the state and use of the page is used to
146 * reduce the requirements down to a memory barrier.
147 * The danger here is of a stale page_mapping() return value
148 * indicating a struct address_space different from the one it's
149 * associated with when it is associated with one.
150 * After smp_mb(), it's either the correct page_mapping() for
151 * the page, or an old page_mapping() and the page's own
152 * page_mapping() has gone NULL.
153 * The ->sync_page() address_space operation must tolerate
154 * page_mapping() going NULL. By an amazing coincidence,
155 * this comes about because none of the users of the page
156 * in the ->sync_page() methods make essential use of the
157 * page_mapping(), merely passing the page down to the backing
158 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700159 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700160 * of interest. When page_mapping() does go NULL, the entire
161 * call stack gracefully ignores the page and returns.
162 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 */
164 smp_mb();
165 mapping = page_mapping(page);
166 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
167 mapping->a_ops->sync_page(page);
168 io_schedule();
169 return 0;
170}
171
172/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700173 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700174 * @mapping: address space structure to write
175 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800176 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700177 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700179 * Start writeback against all of a mapping's dirty pages that lie
180 * within the byte offsets <start, end> inclusive.
181 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700183 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 * these two operations is that if a dirty page/buffer is encountered, it must
185 * be waited upon, and not just skipped over.
186 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800187int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
188 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189{
190 int ret;
191 struct writeback_control wbc = {
192 .sync_mode = sync_mode,
193 .nr_to_write = mapping->nrpages * 2,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700194 .range_start = start,
195 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 };
197
198 if (!mapping_cap_writeback_dirty(mapping))
199 return 0;
200
201 ret = do_writepages(mapping, &wbc);
202 return ret;
203}
204
205static inline int __filemap_fdatawrite(struct address_space *mapping,
206 int sync_mode)
207{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700208 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209}
210
211int filemap_fdatawrite(struct address_space *mapping)
212{
213 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
214}
215EXPORT_SYMBOL(filemap_fdatawrite);
216
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800217static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
218 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219{
220 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
221}
222
Randy Dunlap485bb992006-06-23 02:03:49 -0700223/**
224 * filemap_flush - mostly a non-blocking flush
225 * @mapping: target address_space
226 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 * This is a mostly non-blocking flush. Not suitable for data-integrity
228 * purposes - I/O may not be started against all dirty pages.
229 */
230int filemap_flush(struct address_space *mapping)
231{
232 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
233}
234EXPORT_SYMBOL(filemap_flush);
235
Randy Dunlap485bb992006-06-23 02:03:49 -0700236/**
237 * wait_on_page_writeback_range - wait for writeback to complete
238 * @mapping: target address_space
239 * @start: beginning page index
240 * @end: ending page index
241 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 * Wait for writeback to complete against pages indexed by start->end
243 * inclusive
244 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800245int wait_on_page_writeback_range(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 pgoff_t start, pgoff_t end)
247{
248 struct pagevec pvec;
249 int nr_pages;
250 int ret = 0;
251 pgoff_t index;
252
253 if (end < start)
254 return 0;
255
256 pagevec_init(&pvec, 0);
257 index = start;
258 while ((index <= end) &&
259 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
260 PAGECACHE_TAG_WRITEBACK,
261 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
262 unsigned i;
263
264 for (i = 0; i < nr_pages; i++) {
265 struct page *page = pvec.pages[i];
266
267 /* until radix tree lookup accepts end_index */
268 if (page->index > end)
269 continue;
270
271 wait_on_page_writeback(page);
272 if (PageError(page))
273 ret = -EIO;
274 }
275 pagevec_release(&pvec);
276 cond_resched();
277 }
278
279 /* Check for outstanding write errors */
280 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
281 ret = -ENOSPC;
282 if (test_and_clear_bit(AS_EIO, &mapping->flags))
283 ret = -EIO;
284
285 return ret;
286}
287
Randy Dunlap485bb992006-06-23 02:03:49 -0700288/**
289 * sync_page_range - write and wait on all pages in the passed range
290 * @inode: target inode
291 * @mapping: target address_space
292 * @pos: beginning offset in pages to write
293 * @count: number of bytes to write
294 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 * Write and wait upon all the pages in the passed range. This is a "data
296 * integrity" operation. It waits upon in-flight writeout before starting and
297 * waiting upon new writeout. If there was an IO error, return it.
298 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800299 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 * it is otherwise livelockable.
301 */
302int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800303 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304{
305 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
306 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
307 int ret;
308
309 if (!mapping_cap_writeback_dirty(mapping) || !count)
310 return 0;
311 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
312 if (ret == 0) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800313 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800315 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 }
317 if (ret == 0)
318 ret = wait_on_page_writeback_range(mapping, start, end);
319 return ret;
320}
321EXPORT_SYMBOL(sync_page_range);
322
Randy Dunlap485bb992006-06-23 02:03:49 -0700323/**
324 * sync_page_range_nolock
325 * @inode: target inode
326 * @mapping: target address_space
327 * @pos: beginning offset in pages to write
328 * @count: number of bytes to write
329 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800330 * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 * as it forces O_SYNC writers to different parts of the same file
332 * to be serialised right until io completion.
333 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800334int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
335 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336{
337 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
338 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
339 int ret;
340
341 if (!mapping_cap_writeback_dirty(mapping) || !count)
342 return 0;
343 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
344 if (ret == 0)
345 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
346 if (ret == 0)
347 ret = wait_on_page_writeback_range(mapping, start, end);
348 return ret;
349}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800350EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351
352/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700353 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700355 *
356 * Walk the list of under-writeback pages of the given address space
357 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 */
359int filemap_fdatawait(struct address_space *mapping)
360{
361 loff_t i_size = i_size_read(mapping->host);
362
363 if (i_size == 0)
364 return 0;
365
366 return wait_on_page_writeback_range(mapping, 0,
367 (i_size - 1) >> PAGE_CACHE_SHIFT);
368}
369EXPORT_SYMBOL(filemap_fdatawait);
370
371int filemap_write_and_wait(struct address_space *mapping)
372{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800373 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374
375 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800376 err = filemap_fdatawrite(mapping);
377 /*
378 * Even if the above returned error, the pages may be
379 * written partially (e.g. -ENOSPC), so we wait for it.
380 * But the -EIO is special case, it may indicate the worst
381 * thing (e.g. bug) happened, so we avoid waiting for it.
382 */
383 if (err != -EIO) {
384 int err2 = filemap_fdatawait(mapping);
385 if (!err)
386 err = err2;
387 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800389 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800391EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392
Randy Dunlap485bb992006-06-23 02:03:49 -0700393/**
394 * filemap_write_and_wait_range - write out & wait on a file range
395 * @mapping: the address_space for the pages
396 * @lstart: offset in bytes where the range starts
397 * @lend: offset in bytes where the range ends (inclusive)
398 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800399 * Write out and wait upon file offsets lstart->lend, inclusive.
400 *
401 * Note that `lend' is inclusive (describes the last byte to be written) so
402 * that this function can be used to write to the very end-of-file (end = -1).
403 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404int filemap_write_and_wait_range(struct address_space *mapping,
405 loff_t lstart, loff_t lend)
406{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800407 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408
409 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800410 err = __filemap_fdatawrite_range(mapping, lstart, lend,
411 WB_SYNC_ALL);
412 /* See comment of filemap_write_and_wait() */
413 if (err != -EIO) {
414 int err2 = wait_on_page_writeback_range(mapping,
415 lstart >> PAGE_CACHE_SHIFT,
416 lend >> PAGE_CACHE_SHIFT);
417 if (!err)
418 err = err2;
419 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800421 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422}
423
Randy Dunlap485bb992006-06-23 02:03:49 -0700424/**
425 * add_to_page_cache - add newly allocated pagecache pages
426 * @page: page to add
427 * @mapping: the page's address_space
428 * @offset: page index
429 * @gfp_mask: page allocation mode
430 *
431 * This function is used to add newly allocated pagecache pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 * the page is new, so we can just run SetPageLocked() against it.
433 * The other page state flags were set by rmqueue().
434 *
435 * This function does not add the page to the LRU. The caller must do that.
436 */
437int add_to_page_cache(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400438 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439{
440 int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
441
442 if (error == 0) {
443 write_lock_irq(&mapping->tree_lock);
444 error = radix_tree_insert(&mapping->page_tree, offset, page);
445 if (!error) {
446 page_cache_get(page);
447 SetPageLocked(page);
448 page->mapping = mapping;
449 page->index = offset;
450 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700451 __inc_zone_page_state(page, NR_FILE_PAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 }
453 write_unlock_irq(&mapping->tree_lock);
454 radix_tree_preload_end();
455 }
456 return error;
457}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458EXPORT_SYMBOL(add_to_page_cache);
459
460int add_to_page_cache_lru(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{
463 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
464 if (ret == 0)
465 lru_cache_add(page);
466 return ret;
467}
468
Paul Jackson44110fe2006-03-24 03:16:04 -0800469#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700470struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800471{
472 if (cpuset_do_page_mem_spread()) {
473 int n = cpuset_mem_spread_node();
Nick Piggin2ae88142006-10-28 10:38:23 -0700474 return alloc_pages_node(n, gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800475 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700476 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800477}
Nick Piggin2ae88142006-10-28 10:38:23 -0700478EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800479#endif
480
Nick Piggindb376482006-09-25 23:31:24 -0700481static int __sleep_on_page_lock(void *word)
482{
483 io_schedule();
484 return 0;
485}
486
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487/*
488 * In order to wait for pages to become available there must be
489 * waitqueues associated with pages. By using a hash table of
490 * waitqueues where the bucket discipline is to maintain all
491 * waiters on the same queue and wake all when any of the pages
492 * become available, and for the woken contexts to check to be
493 * sure the appropriate page became available, this saves space
494 * at a cost of "thundering herd" phenomena during rare hash
495 * collisions.
496 */
497static wait_queue_head_t *page_waitqueue(struct page *page)
498{
499 const struct zone *zone = page_zone(page);
500
501 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
502}
503
504static inline void wake_up_page(struct page *page, int bit)
505{
506 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
507}
508
509void fastcall wait_on_page_bit(struct page *page, int bit_nr)
510{
511 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
512
513 if (test_bit(bit_nr, &page->flags))
514 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
515 TASK_UNINTERRUPTIBLE);
516}
517EXPORT_SYMBOL(wait_on_page_bit);
518
519/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700520 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700521 * @page: the page
522 *
523 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
524 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
525 * mechananism between PageLocked pages and PageWriteback pages is shared.
526 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
527 *
528 * The first mb is necessary to safely close the critical section opened by the
529 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
530 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
531 * parallel wait_on_page_locked()).
532 */
533void fastcall unlock_page(struct page *page)
534{
535 smp_mb__before_clear_bit();
536 if (!TestClearPageLocked(page))
537 BUG();
538 smp_mb__after_clear_bit();
539 wake_up_page(page, PG_locked);
540}
541EXPORT_SYMBOL(unlock_page);
542
Randy Dunlap485bb992006-06-23 02:03:49 -0700543/**
544 * end_page_writeback - end writeback against a page
545 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 */
547void end_page_writeback(struct page *page)
548{
549 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
550 if (!test_clear_page_writeback(page))
551 BUG();
552 }
553 smp_mb__after_clear_bit();
554 wake_up_page(page, PG_writeback);
555}
556EXPORT_SYMBOL(end_page_writeback);
557
Randy Dunlap485bb992006-06-23 02:03:49 -0700558/**
559 * __lock_page - get a lock on the page, assuming we need to sleep to get it
560 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700562 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
564 * chances are that on the second loop, the block layer's plug list is empty,
565 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
566 */
567void fastcall __lock_page(struct page *page)
568{
569 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
570
571 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
572 TASK_UNINTERRUPTIBLE);
573}
574EXPORT_SYMBOL(__lock_page);
575
Nick Piggindb376482006-09-25 23:31:24 -0700576/*
577 * Variant of lock_page that does not require the caller to hold a reference
578 * on the page's mapping.
579 */
580void fastcall __lock_page_nosync(struct page *page)
581{
582 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
583 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
584 TASK_UNINTERRUPTIBLE);
585}
586
Randy Dunlap485bb992006-06-23 02:03:49 -0700587/**
588 * find_get_page - find and get a page reference
589 * @mapping: the address_space to search
590 * @offset: the page index
591 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700592 * Is there a pagecache struct page at the given (mapping, offset) tuple?
593 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 */
595struct page * find_get_page(struct address_space *mapping, unsigned long offset)
596{
597 struct page *page;
598
599 read_lock_irq(&mapping->tree_lock);
600 page = radix_tree_lookup(&mapping->page_tree, offset);
601 if (page)
602 page_cache_get(page);
603 read_unlock_irq(&mapping->tree_lock);
604 return page;
605}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606EXPORT_SYMBOL(find_get_page);
607
Randy Dunlap485bb992006-06-23 02:03:49 -0700608/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700610 * @mapping: the address_space to search
611 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 *
613 * Locates the desired pagecache page, locks it, increments its reference
614 * count and returns its address.
615 *
616 * Returns zero if the page was not present. find_lock_page() may sleep.
617 */
618struct page *find_lock_page(struct address_space *mapping,
619 unsigned long offset)
620{
621 struct page *page;
622
623 read_lock_irq(&mapping->tree_lock);
624repeat:
625 page = radix_tree_lookup(&mapping->page_tree, offset);
626 if (page) {
627 page_cache_get(page);
628 if (TestSetPageLocked(page)) {
629 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800630 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 read_lock_irq(&mapping->tree_lock);
632
633 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800634 if (unlikely(page->mapping != mapping ||
635 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 unlock_page(page);
637 page_cache_release(page);
638 goto repeat;
639 }
640 }
641 }
642 read_unlock_irq(&mapping->tree_lock);
643 return page;
644}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645EXPORT_SYMBOL(find_lock_page);
646
647/**
648 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700649 * @mapping: the page's address_space
650 * @index: the page's index into the mapping
651 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 *
653 * Locates a page in the pagecache. If the page is not present, a new page
654 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
655 * LRU list. The returned page is locked and has its reference count
656 * incremented.
657 *
658 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
659 * allocation!
660 *
661 * find_or_create_page() returns the desired page's address, or zero on
662 * memory exhaustion.
663 */
664struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400665 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666{
667 struct page *page, *cached_page = NULL;
668 int err;
669repeat:
670 page = find_lock_page(mapping, index);
671 if (!page) {
672 if (!cached_page) {
Christoph Lameter43c0f3d2007-05-15 23:57:09 -0700673 cached_page =
674 __page_cache_alloc(gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 if (!cached_page)
676 return NULL;
677 }
678 err = add_to_page_cache_lru(cached_page, mapping,
679 index, gfp_mask);
680 if (!err) {
681 page = cached_page;
682 cached_page = NULL;
683 } else if (err == -EEXIST)
684 goto repeat;
685 }
686 if (cached_page)
687 page_cache_release(cached_page);
688 return page;
689}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690EXPORT_SYMBOL(find_or_create_page);
691
692/**
693 * find_get_pages - gang pagecache lookup
694 * @mapping: The address_space to search
695 * @start: The starting page index
696 * @nr_pages: The maximum number of pages
697 * @pages: Where the resulting pages are placed
698 *
699 * find_get_pages() will search for and return a group of up to
700 * @nr_pages pages in the mapping. The pages are placed at @pages.
701 * find_get_pages() takes a reference against the returned pages.
702 *
703 * The search returns a group of mapping-contiguous pages with ascending
704 * indexes. There may be holes in the indices due to not-present pages.
705 *
706 * find_get_pages() returns the number of pages which were found.
707 */
708unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
709 unsigned int nr_pages, struct page **pages)
710{
711 unsigned int i;
712 unsigned int ret;
713
714 read_lock_irq(&mapping->tree_lock);
715 ret = radix_tree_gang_lookup(&mapping->page_tree,
716 (void **)pages, start, nr_pages);
717 for (i = 0; i < ret; i++)
718 page_cache_get(pages[i]);
719 read_unlock_irq(&mapping->tree_lock);
720 return ret;
721}
722
Jens Axboeebf43502006-04-27 08:46:01 +0200723/**
724 * find_get_pages_contig - gang contiguous pagecache lookup
725 * @mapping: The address_space to search
726 * @index: The starting page index
727 * @nr_pages: The maximum number of pages
728 * @pages: Where the resulting pages are placed
729 *
730 * find_get_pages_contig() works exactly like find_get_pages(), except
731 * that the returned number of pages are guaranteed to be contiguous.
732 *
733 * find_get_pages_contig() returns the number of pages which were found.
734 */
735unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
736 unsigned int nr_pages, struct page **pages)
737{
738 unsigned int i;
739 unsigned int ret;
740
741 read_lock_irq(&mapping->tree_lock);
742 ret = radix_tree_gang_lookup(&mapping->page_tree,
743 (void **)pages, index, nr_pages);
744 for (i = 0; i < ret; i++) {
745 if (pages[i]->mapping == NULL || pages[i]->index != index)
746 break;
747
748 page_cache_get(pages[i]);
749 index++;
750 }
751 read_unlock_irq(&mapping->tree_lock);
752 return i;
753}
David Howellsef71c152007-05-09 02:33:44 -0700754EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200755
Randy Dunlap485bb992006-06-23 02:03:49 -0700756/**
757 * find_get_pages_tag - find and return pages that match @tag
758 * @mapping: the address_space to search
759 * @index: the starting page index
760 * @tag: the tag index
761 * @nr_pages: the maximum number of pages
762 * @pages: where the resulting pages are placed
763 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700765 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 */
767unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
768 int tag, unsigned int nr_pages, struct page **pages)
769{
770 unsigned int i;
771 unsigned int ret;
772
773 read_lock_irq(&mapping->tree_lock);
774 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
775 (void **)pages, *index, nr_pages, tag);
776 for (i = 0; i < ret; i++)
777 page_cache_get(pages[i]);
778 if (ret)
779 *index = pages[ret - 1]->index + 1;
780 read_unlock_irq(&mapping->tree_lock);
781 return ret;
782}
David Howellsef71c152007-05-09 02:33:44 -0700783EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784
Randy Dunlap485bb992006-06-23 02:03:49 -0700785/**
786 * grab_cache_page_nowait - returns locked page at given index in given cache
787 * @mapping: target address_space
788 * @index: the page index
789 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800790 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 * This is intended for speculative data generators, where the data can
792 * be regenerated if the page couldn't be grabbed. This routine should
793 * be safe to call while holding the lock for another page.
794 *
795 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
796 * and deadlock against the caller's locked page.
797 */
798struct page *
799grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
800{
801 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700802
803 if (page) {
804 if (!TestSetPageLocked(page))
805 return page;
806 page_cache_release(page);
807 return NULL;
808 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700809 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
810 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 page_cache_release(page);
812 page = NULL;
813 }
814 return page;
815}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816EXPORT_SYMBOL(grab_cache_page_nowait);
817
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700818/*
819 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
820 * a _large_ part of the i/o request. Imagine the worst scenario:
821 *
822 * ---R__________________________________________B__________
823 * ^ reading here ^ bad block(assume 4k)
824 *
825 * read(R) => miss => readahead(R...B) => media error => frustrating retries
826 * => failing the whole request => read(R) => read(R+1) =>
827 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
828 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
829 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
830 *
831 * It is going insane. Fix it by quickly scaling down the readahead size.
832 */
833static void shrink_readahead_size_eio(struct file *filp,
834 struct file_ra_state *ra)
835{
836 if (!ra->ra_pages)
837 return;
838
839 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700840}
841
Randy Dunlap485bb992006-06-23 02:03:49 -0700842/**
843 * do_generic_mapping_read - generic file read routine
844 * @mapping: address_space to be read
845 * @_ra: file's readahead state
846 * @filp: the file to read
847 * @ppos: current file position
848 * @desc: read_descriptor
849 * @actor: read method
850 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700852 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853 *
854 * This is really ugly. But the goto's actually try to clarify some
855 * of the logic when it comes to error handling etc.
856 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700857 * Note the struct file* is only passed for the use of readpage.
858 * It may be NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700859 */
860void do_generic_mapping_read(struct address_space *mapping,
861 struct file_ra_state *_ra,
862 struct file *filp,
863 loff_t *ppos,
864 read_descriptor_t *desc,
865 read_actor_t actor)
866{
867 struct inode *inode = mapping->host;
868 unsigned long index;
869 unsigned long end_index;
870 unsigned long offset;
871 unsigned long last_index;
872 unsigned long next_index;
873 unsigned long prev_index;
Jan Karaec0f1632007-05-06 14:49:25 -0700874 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 loff_t isize;
876 struct page *cached_page;
877 int error;
878 struct file_ra_state ra = *_ra;
879
880 cached_page = NULL;
881 index = *ppos >> PAGE_CACHE_SHIFT;
882 next_index = index;
Jan Kara6ce745e2007-05-06 14:49:26 -0700883 prev_index = ra.prev_index;
884 prev_offset = ra.prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
886 offset = *ppos & ~PAGE_CACHE_MASK;
887
888 isize = i_size_read(inode);
889 if (!isize)
890 goto out;
891
892 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
893 for (;;) {
894 struct page *page;
895 unsigned long nr, ret;
896
897 /* nr is the maximum number of bytes to copy from this page */
898 nr = PAGE_CACHE_SIZE;
899 if (index >= end_index) {
900 if (index > end_index)
901 goto out;
902 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
903 if (nr <= offset) {
904 goto out;
905 }
906 }
907 nr = nr - offset;
908
909 cond_resched();
910 if (index == next_index)
911 next_index = page_cache_readahead(mapping, &ra, filp,
912 index, last_index - index);
913
914find_page:
915 page = find_get_page(mapping, index);
916 if (unlikely(page == NULL)) {
917 handle_ra_miss(mapping, &ra, index);
918 goto no_cached_page;
919 }
920 if (!PageUptodate(page))
921 goto page_not_up_to_date;
922page_ok:
923
924 /* If users can be writing to this page using arbitrary
925 * virtual addresses, take care about potential aliasing
926 * before reading the page on the kernel side.
927 */
928 if (mapping_writably_mapped(mapping))
929 flush_dcache_page(page);
930
931 /*
Jan Karaec0f1632007-05-06 14:49:25 -0700932 * When a sequential read accesses a page several times,
933 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934 */
Jan Karaec0f1632007-05-06 14:49:25 -0700935 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 mark_page_accessed(page);
937 prev_index = index;
938
939 /*
940 * Ok, we have the page, and it's up-to-date, so
941 * now we can copy it to user space...
942 *
943 * The actor routine returns how many bytes were actually used..
944 * NOTE! This may not be the same as how much of a user buffer
945 * we filled up (we may be padding etc), so we can only update
946 * "pos" here (the actor routine has to update the user buffer
947 * pointers and the remaining count).
948 */
949 ret = actor(desc, page, offset, nr);
950 offset += ret;
951 index += offset >> PAGE_CACHE_SHIFT;
952 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -0700953 prev_offset = offset;
954 ra.prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955
956 page_cache_release(page);
957 if (ret == nr && desc->count)
958 continue;
959 goto out;
960
961page_not_up_to_date:
962 /* Get exclusive access to the page ... */
963 lock_page(page);
964
Nick Pigginda6052f2006-09-25 23:31:35 -0700965 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966 if (!page->mapping) {
967 unlock_page(page);
968 page_cache_release(page);
969 continue;
970 }
971
972 /* Did somebody else fill it already? */
973 if (PageUptodate(page)) {
974 unlock_page(page);
975 goto page_ok;
976 }
977
978readpage:
979 /* Start the actual read. The read will unlock the page. */
980 error = mapping->a_ops->readpage(filp, page);
981
Zach Brown994fc28c2005-12-15 14:28:17 -0800982 if (unlikely(error)) {
983 if (error == AOP_TRUNCATED_PAGE) {
984 page_cache_release(page);
985 goto find_page;
986 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800988 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989
990 if (!PageUptodate(page)) {
991 lock_page(page);
992 if (!PageUptodate(page)) {
993 if (page->mapping == NULL) {
994 /*
995 * invalidate_inode_pages got it
996 */
997 unlock_page(page);
998 page_cache_release(page);
999 goto find_page;
1000 }
1001 unlock_page(page);
1002 error = -EIO;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001003 shrink_readahead_size_eio(filp, &ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 goto readpage_error;
1005 }
1006 unlock_page(page);
1007 }
1008
1009 /*
1010 * i_size must be checked after we have done ->readpage.
1011 *
1012 * Checking i_size after the readpage allows us to calculate
1013 * the correct value for "nr", which means the zero-filled
1014 * part of the page is not copied back to userspace (unless
1015 * another truncate extends the file - this is desired though).
1016 */
1017 isize = i_size_read(inode);
1018 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1019 if (unlikely(!isize || index > end_index)) {
1020 page_cache_release(page);
1021 goto out;
1022 }
1023
1024 /* nr is the maximum number of bytes to copy from this page */
1025 nr = PAGE_CACHE_SIZE;
1026 if (index == end_index) {
1027 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1028 if (nr <= offset) {
1029 page_cache_release(page);
1030 goto out;
1031 }
1032 }
1033 nr = nr - offset;
1034 goto page_ok;
1035
1036readpage_error:
1037 /* UHHUH! A synchronous read error occurred. Report it */
1038 desc->error = error;
1039 page_cache_release(page);
1040 goto out;
1041
1042no_cached_page:
1043 /*
1044 * Ok, it wasn't cached, so we need to create a new
1045 * page..
1046 */
1047 if (!cached_page) {
1048 cached_page = page_cache_alloc_cold(mapping);
1049 if (!cached_page) {
1050 desc->error = -ENOMEM;
1051 goto out;
1052 }
1053 }
1054 error = add_to_page_cache_lru(cached_page, mapping,
1055 index, GFP_KERNEL);
1056 if (error) {
1057 if (error == -EEXIST)
1058 goto find_page;
1059 desc->error = error;
1060 goto out;
1061 }
1062 page = cached_page;
1063 cached_page = NULL;
1064 goto readpage;
1065 }
1066
1067out:
1068 *_ra = ra;
1069
1070 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1071 if (cached_page)
1072 page_cache_release(cached_page);
1073 if (filp)
1074 file_accessed(filp);
1075}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076EXPORT_SYMBOL(do_generic_mapping_read);
1077
1078int file_read_actor(read_descriptor_t *desc, struct page *page,
1079 unsigned long offset, unsigned long size)
1080{
1081 char *kaddr;
1082 unsigned long left, count = desc->count;
1083
1084 if (size > count)
1085 size = count;
1086
1087 /*
1088 * Faults on the destination of a read are common, so do it before
1089 * taking the kmap.
1090 */
1091 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1092 kaddr = kmap_atomic(page, KM_USER0);
1093 left = __copy_to_user_inatomic(desc->arg.buf,
1094 kaddr + offset, size);
1095 kunmap_atomic(kaddr, KM_USER0);
1096 if (left == 0)
1097 goto success;
1098 }
1099
1100 /* Do it the slow way */
1101 kaddr = kmap(page);
1102 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1103 kunmap(page);
1104
1105 if (left) {
1106 size -= left;
1107 desc->error = -EFAULT;
1108 }
1109success:
1110 desc->count = count - size;
1111 desc->written += size;
1112 desc->arg.buf += size;
1113 return size;
1114}
1115
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001116/*
1117 * Performs necessary checks before doing a write
1118 * @iov: io vector request
1119 * @nr_segs: number of segments in the iovec
1120 * @count: number of bytes to write
1121 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1122 *
1123 * Adjust number of segments and amount of bytes to write (nr_segs should be
1124 * properly initialized first). Returns appropriate error code that caller
1125 * should return or zero in case that write should be allowed.
1126 */
1127int generic_segment_checks(const struct iovec *iov,
1128 unsigned long *nr_segs, size_t *count, int access_flags)
1129{
1130 unsigned long seg;
1131 size_t cnt = 0;
1132 for (seg = 0; seg < *nr_segs; seg++) {
1133 const struct iovec *iv = &iov[seg];
1134
1135 /*
1136 * If any segment has a negative length, or the cumulative
1137 * length ever wraps negative then return -EINVAL.
1138 */
1139 cnt += iv->iov_len;
1140 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1141 return -EINVAL;
1142 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1143 continue;
1144 if (seg == 0)
1145 return -EFAULT;
1146 *nr_segs = seg;
1147 cnt -= iv->iov_len; /* This segment is no good */
1148 break;
1149 }
1150 *count = cnt;
1151 return 0;
1152}
1153EXPORT_SYMBOL(generic_segment_checks);
1154
Randy Dunlap485bb992006-06-23 02:03:49 -07001155/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001156 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001157 * @iocb: kernel I/O control block
1158 * @iov: io vector request
1159 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001160 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001161 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 * This is the "read()" routine for all filesystems
1163 * that can use the page cache directly.
1164 */
1165ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001166generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1167 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168{
1169 struct file *filp = iocb->ki_filp;
1170 ssize_t retval;
1171 unsigned long seg;
1172 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001173 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174
1175 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001176 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1177 if (retval)
1178 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179
1180 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1181 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001182 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 struct address_space *mapping;
1184 struct inode *inode;
1185
1186 mapping = filp->f_mapping;
1187 inode = mapping->host;
1188 retval = 0;
1189 if (!count)
1190 goto out; /* skip atime */
1191 size = i_size_read(inode);
1192 if (pos < size) {
1193 retval = generic_file_direct_IO(READ, iocb,
1194 iov, pos, nr_segs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 if (retval > 0)
1196 *ppos = pos + retval;
1197 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001198 if (likely(retval != 0)) {
Steven Whitehouse3f1a9aa2006-09-27 14:52:48 -04001199 file_accessed(filp);
Steven Whitehousea9e5f4d2006-07-25 17:24:12 -04001200 goto out;
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001201 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001202 }
1203
1204 retval = 0;
1205 if (count) {
1206 for (seg = 0; seg < nr_segs; seg++) {
1207 read_descriptor_t desc;
1208
1209 desc.written = 0;
1210 desc.arg.buf = iov[seg].iov_base;
1211 desc.count = iov[seg].iov_len;
1212 if (desc.count == 0)
1213 continue;
1214 desc.error = 0;
1215 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1216 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001217 if (desc.error) {
1218 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 break;
1220 }
1221 }
1222 }
1223out:
1224 return retval;
1225}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226EXPORT_SYMBOL(generic_file_aio_read);
1227
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1229{
1230 ssize_t written;
1231 unsigned long count = desc->count;
1232 struct file *file = desc->arg.data;
1233
1234 if (size > count)
1235 size = count;
1236
1237 written = file->f_op->sendpage(file, page, offset,
1238 size, &file->f_pos, size<count);
1239 if (written < 0) {
1240 desc->error = written;
1241 written = 0;
1242 }
1243 desc->count = count - written;
1244 desc->written += written;
1245 return written;
1246}
1247
1248ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1249 size_t count, read_actor_t actor, void *target)
1250{
1251 read_descriptor_t desc;
1252
1253 if (!count)
1254 return 0;
1255
1256 desc.written = 0;
1257 desc.count = count;
1258 desc.arg.data = target;
1259 desc.error = 0;
1260
1261 do_generic_file_read(in_file, ppos, &desc, actor);
1262 if (desc.written)
1263 return desc.written;
1264 return desc.error;
1265}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001266EXPORT_SYMBOL(generic_file_sendfile);
1267
1268static ssize_t
1269do_readahead(struct address_space *mapping, struct file *filp,
1270 unsigned long index, unsigned long nr)
1271{
1272 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1273 return -EINVAL;
1274
1275 force_page_cache_readahead(mapping, filp, index,
1276 max_sane_readahead(nr));
1277 return 0;
1278}
1279
1280asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1281{
1282 ssize_t ret;
1283 struct file *file;
1284
1285 ret = -EBADF;
1286 file = fget(fd);
1287 if (file) {
1288 if (file->f_mode & FMODE_READ) {
1289 struct address_space *mapping = file->f_mapping;
1290 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1291 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1292 unsigned long len = end - start + 1;
1293 ret = do_readahead(mapping, file, start, len);
1294 }
1295 fput(file);
1296 }
1297 return ret;
1298}
1299
1300#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001301static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1302/**
1303 * page_cache_read - adds requested page to the page cache if not already there
1304 * @file: file to read
1305 * @offset: page index
1306 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307 * This adds the requested page to the page cache if it isn't already there,
1308 * and schedules an I/O to read in its contents from disk.
1309 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310static int fastcall page_cache_read(struct file * file, unsigned long offset)
1311{
1312 struct address_space *mapping = file->f_mapping;
1313 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001314 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315
Zach Brown994fc28c2005-12-15 14:28:17 -08001316 do {
1317 page = page_cache_alloc_cold(mapping);
1318 if (!page)
1319 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320
Zach Brown994fc28c2005-12-15 14:28:17 -08001321 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1322 if (ret == 0)
1323 ret = mapping->a_ops->readpage(file, page);
1324 else if (ret == -EEXIST)
1325 ret = 0; /* losing race to add is OK */
1326
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328
Zach Brown994fc28c2005-12-15 14:28:17 -08001329 } while (ret == AOP_TRUNCATED_PAGE);
1330
1331 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332}
1333
1334#define MMAP_LOTSAMISS (100)
1335
Randy Dunlap485bb992006-06-23 02:03:49 -07001336/**
1337 * filemap_nopage - read in file data for page fault handling
1338 * @area: the applicable vm_area
1339 * @address: target address to read in
1340 * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1341 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 * filemap_nopage() is invoked via the vma operations vector for a
1343 * mapped memory region to read in file data during a page fault.
1344 *
1345 * The goto's are kind of ugly, but this streamlines the normal case of having
1346 * it in the page cache, and handles the special cases reasonably without
1347 * having a lot of duplicated code.
1348 */
1349struct page *filemap_nopage(struct vm_area_struct *area,
1350 unsigned long address, int *type)
1351{
1352 int error;
1353 struct file *file = area->vm_file;
1354 struct address_space *mapping = file->f_mapping;
1355 struct file_ra_state *ra = &file->f_ra;
1356 struct inode *inode = mapping->host;
1357 struct page *page;
1358 unsigned long size, pgoff;
1359 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1360
1361 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1362
1363retry_all:
1364 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1365 if (pgoff >= size)
1366 goto outside_data_content;
1367
1368 /* If we don't want any read-ahead, don't bother */
1369 if (VM_RandomReadHint(area))
1370 goto no_cached_page;
1371
1372 /*
1373 * The readahead code wants to be told about each and every page
1374 * so it can build and shrink its windows appropriately
1375 *
1376 * For sequential accesses, we use the generic readahead logic.
1377 */
1378 if (VM_SequentialReadHint(area))
1379 page_cache_readahead(mapping, ra, file, pgoff, 1);
1380
1381 /*
1382 * Do we have something in the page cache already?
1383 */
1384retry_find:
1385 page = find_get_page(mapping, pgoff);
1386 if (!page) {
1387 unsigned long ra_pages;
1388
1389 if (VM_SequentialReadHint(area)) {
1390 handle_ra_miss(mapping, ra, pgoff);
1391 goto no_cached_page;
1392 }
1393 ra->mmap_miss++;
1394
1395 /*
1396 * Do we miss much more than hit in this file? If so,
1397 * stop bothering with read-ahead. It will only hurt.
1398 */
1399 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1400 goto no_cached_page;
1401
1402 /*
1403 * To keep the pgmajfault counter straight, we need to
1404 * check did_readaround, as this is an inner loop.
1405 */
1406 if (!did_readaround) {
1407 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001408 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409 }
1410 did_readaround = 1;
1411 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1412 if (ra_pages) {
1413 pgoff_t start = 0;
1414
1415 if (pgoff > ra_pages / 2)
1416 start = pgoff - ra_pages / 2;
1417 do_page_cache_readahead(mapping, file, start, ra_pages);
1418 }
1419 page = find_get_page(mapping, pgoff);
1420 if (!page)
1421 goto no_cached_page;
1422 }
1423
1424 if (!did_readaround)
1425 ra->mmap_hit++;
1426
1427 /*
1428 * Ok, found a page in the page cache, now we need to check
1429 * that it's up-to-date.
1430 */
1431 if (!PageUptodate(page))
1432 goto page_not_uptodate;
1433
1434success:
1435 /*
1436 * Found the page and have a reference on it.
1437 */
1438 mark_page_accessed(page);
1439 if (type)
1440 *type = majmin;
1441 return page;
1442
1443outside_data_content:
1444 /*
1445 * An external ptracer can access pages that normally aren't
1446 * accessible..
1447 */
1448 if (area->vm_mm == current->mm)
Adam Litke79f5acf2006-09-29 01:58:43 -07001449 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450 /* Fall through to the non-read-ahead case */
1451no_cached_page:
1452 /*
1453 * We're only likely to ever get here if MADV_RANDOM is in
1454 * effect.
1455 */
1456 error = page_cache_read(file, pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457
1458 /*
1459 * The page we want has now been added to the page cache.
1460 * In the unlikely event that someone removed it in the
1461 * meantime, we'll just come back here and read it again.
1462 */
1463 if (error >= 0)
1464 goto retry_find;
1465
1466 /*
1467 * An error return from page_cache_read can result if the
1468 * system is low on memory, or a problem occurs while trying
1469 * to schedule I/O.
1470 */
1471 if (error == -ENOMEM)
1472 return NOPAGE_OOM;
Adam Litke79f5acf2006-09-29 01:58:43 -07001473 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474
1475page_not_uptodate:
1476 if (!did_readaround) {
1477 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001478 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480
1481 /*
1482 * Umm, take care of errors if the page isn't up-to-date.
1483 * Try to re-read it _once_. We do this synchronously,
1484 * because there really aren't any performance issues here
1485 * and we need to check for errors.
1486 */
1487 lock_page(page);
1488
1489 /* Somebody truncated the page on us? */
1490 if (!page->mapping) {
1491 unlock_page(page);
1492 page_cache_release(page);
1493 goto retry_all;
1494 }
1495
1496 /* Somebody else successfully read it in? */
1497 if (PageUptodate(page)) {
1498 unlock_page(page);
1499 goto success;
1500 }
1501 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001502 error = mapping->a_ops->readpage(file, page);
1503 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 wait_on_page_locked(page);
1505 if (PageUptodate(page))
1506 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001507 } else if (error == AOP_TRUNCATED_PAGE) {
1508 page_cache_release(page);
1509 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 }
1511
1512 /*
1513 * Things didn't work out. Return zero to tell the
1514 * mm layer so, possibly freeing the page cache page first.
1515 */
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001516 shrink_readahead_size_eio(file, ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 page_cache_release(page);
Adam Litke79f5acf2006-09-29 01:58:43 -07001518 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001520EXPORT_SYMBOL(filemap_nopage);
1521
1522static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1523 int nonblock)
1524{
1525 struct address_space *mapping = file->f_mapping;
1526 struct page *page;
1527 int error;
1528
1529 /*
1530 * Do we have something in the page cache already?
1531 */
1532retry_find:
1533 page = find_get_page(mapping, pgoff);
1534 if (!page) {
1535 if (nonblock)
1536 return NULL;
1537 goto no_cached_page;
1538 }
1539
1540 /*
1541 * Ok, found a page in the page cache, now we need to check
1542 * that it's up-to-date.
1543 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001544 if (!PageUptodate(page)) {
1545 if (nonblock) {
1546 page_cache_release(page);
1547 return NULL;
1548 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001550 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551
1552success:
1553 /*
1554 * Found the page and have a reference on it.
1555 */
1556 mark_page_accessed(page);
1557 return page;
1558
1559no_cached_page:
1560 error = page_cache_read(file, pgoff);
1561
1562 /*
1563 * The page we want has now been added to the page cache.
1564 * In the unlikely event that someone removed it in the
1565 * meantime, we'll just come back here and read it again.
1566 */
1567 if (error >= 0)
1568 goto retry_find;
1569
1570 /*
1571 * An error return from page_cache_read can result if the
1572 * system is low on memory, or a problem occurs while trying
1573 * to schedule I/O.
1574 */
1575 return NULL;
1576
1577page_not_uptodate:
1578 lock_page(page);
1579
Nick Pigginda6052f2006-09-25 23:31:35 -07001580 /* Did it get truncated while we waited for it? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 if (!page->mapping) {
1582 unlock_page(page);
1583 goto err;
1584 }
1585
1586 /* Did somebody else get it up-to-date? */
1587 if (PageUptodate(page)) {
1588 unlock_page(page);
1589 goto success;
1590 }
1591
Zach Brown994fc28c2005-12-15 14:28:17 -08001592 error = mapping->a_ops->readpage(file, page);
1593 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 wait_on_page_locked(page);
1595 if (PageUptodate(page))
1596 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001597 } else if (error == AOP_TRUNCATED_PAGE) {
1598 page_cache_release(page);
1599 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600 }
1601
1602 /*
1603 * Umm, take care of errors if the page isn't up-to-date.
1604 * Try to re-read it _once_. We do this synchronously,
1605 * because there really aren't any performance issues here
1606 * and we need to check for errors.
1607 */
1608 lock_page(page);
1609
1610 /* Somebody truncated the page on us? */
1611 if (!page->mapping) {
1612 unlock_page(page);
1613 goto err;
1614 }
1615 /* Somebody else successfully read it in? */
1616 if (PageUptodate(page)) {
1617 unlock_page(page);
1618 goto success;
1619 }
1620
1621 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001622 error = mapping->a_ops->readpage(file, page);
1623 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 wait_on_page_locked(page);
1625 if (PageUptodate(page))
1626 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001627 } else if (error == AOP_TRUNCATED_PAGE) {
1628 page_cache_release(page);
1629 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 }
1631
1632 /*
1633 * Things didn't work out. Return zero to tell the
1634 * mm layer so, possibly freeing the page cache page first.
1635 */
1636err:
1637 page_cache_release(page);
1638
1639 return NULL;
1640}
1641
1642int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1643 unsigned long len, pgprot_t prot, unsigned long pgoff,
1644 int nonblock)
1645{
1646 struct file *file = vma->vm_file;
1647 struct address_space *mapping = file->f_mapping;
1648 struct inode *inode = mapping->host;
1649 unsigned long size;
1650 struct mm_struct *mm = vma->vm_mm;
1651 struct page *page;
1652 int err;
1653
1654 if (!nonblock)
1655 force_page_cache_readahead(mapping, vma->vm_file,
1656 pgoff, len >> PAGE_CACHE_SHIFT);
1657
1658repeat:
1659 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1660 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1661 return -EINVAL;
1662
1663 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001664
1665 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1666 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 if (!page && !nonblock)
1668 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001669
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670 if (page) {
1671 err = install_page(mm, vma, addr, page, prot);
1672 if (err) {
1673 page_cache_release(page);
1674 return err;
1675 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001676 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001677 /* No page was found just because we can't read it in now (being
1678 * here implies nonblock != 0), but the page may exist, so set
1679 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 err = install_file_pte(mm, vma, addr, pgoff, prot);
1681 if (err)
1682 return err;
1683 }
1684
1685 len -= PAGE_SIZE;
1686 addr += PAGE_SIZE;
1687 pgoff++;
1688 if (len)
1689 goto repeat;
1690
1691 return 0;
1692}
Nikita Danilovb1459462005-10-29 18:17:02 -07001693EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694
1695struct vm_operations_struct generic_file_vm_ops = {
1696 .nopage = filemap_nopage,
1697 .populate = filemap_populate,
1698};
1699
1700/* This is used for a general mmap of a disk file */
1701
1702int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1703{
1704 struct address_space *mapping = file->f_mapping;
1705
1706 if (!mapping->a_ops->readpage)
1707 return -ENOEXEC;
1708 file_accessed(file);
1709 vma->vm_ops = &generic_file_vm_ops;
1710 return 0;
1711}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
1713/*
1714 * This is for filesystems which do not implement ->writepage.
1715 */
1716int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1717{
1718 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1719 return -EINVAL;
1720 return generic_file_mmap(file, vma);
1721}
1722#else
1723int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1724{
1725 return -ENOSYS;
1726}
1727int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1728{
1729 return -ENOSYS;
1730}
1731#endif /* CONFIG_MMU */
1732
1733EXPORT_SYMBOL(generic_file_mmap);
1734EXPORT_SYMBOL(generic_file_readonly_mmap);
1735
Nick Piggin6fe69002007-05-06 14:49:04 -07001736static struct page *__read_cache_page(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 unsigned long index,
1738 int (*filler)(void *,struct page*),
1739 void *data)
1740{
1741 struct page *page, *cached_page = NULL;
1742 int err;
1743repeat:
1744 page = find_get_page(mapping, index);
1745 if (!page) {
1746 if (!cached_page) {
1747 cached_page = page_cache_alloc_cold(mapping);
1748 if (!cached_page)
1749 return ERR_PTR(-ENOMEM);
1750 }
1751 err = add_to_page_cache_lru(cached_page, mapping,
1752 index, GFP_KERNEL);
1753 if (err == -EEXIST)
1754 goto repeat;
1755 if (err < 0) {
1756 /* Presumably ENOMEM for radix tree node */
1757 page_cache_release(cached_page);
1758 return ERR_PTR(err);
1759 }
1760 page = cached_page;
1761 cached_page = NULL;
1762 err = filler(data, page);
1763 if (err < 0) {
1764 page_cache_release(page);
1765 page = ERR_PTR(err);
1766 }
1767 }
1768 if (cached_page)
1769 page_cache_release(cached_page);
1770 return page;
1771}
1772
Nick Piggin6fe69002007-05-06 14:49:04 -07001773/*
1774 * Same as read_cache_page, but don't wait for page to become unlocked
1775 * after submitting it to the filler.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 */
Nick Piggin6fe69002007-05-06 14:49:04 -07001777struct page *read_cache_page_async(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 unsigned long index,
1779 int (*filler)(void *,struct page*),
1780 void *data)
1781{
1782 struct page *page;
1783 int err;
1784
1785retry:
1786 page = __read_cache_page(mapping, index, filler, data);
1787 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001788 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 mark_page_accessed(page);
1790 if (PageUptodate(page))
1791 goto out;
1792
1793 lock_page(page);
1794 if (!page->mapping) {
1795 unlock_page(page);
1796 page_cache_release(page);
1797 goto retry;
1798 }
1799 if (PageUptodate(page)) {
1800 unlock_page(page);
1801 goto out;
1802 }
1803 err = filler(data, page);
1804 if (err < 0) {
1805 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001806 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807 }
David Howellsc855ff32007-05-09 13:42:20 +01001808out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001809 mark_page_accessed(page);
1810 return page;
1811}
1812EXPORT_SYMBOL(read_cache_page_async);
1813
1814/**
1815 * read_cache_page - read into page cache, fill it if needed
1816 * @mapping: the page's address_space
1817 * @index: the page index
1818 * @filler: function to perform the read
1819 * @data: destination for read data
1820 *
1821 * Read into the page cache. If a page already exists, and PageUptodate() is
1822 * not set, try to fill the page then wait for it to become unlocked.
1823 *
1824 * If the page does not get brought uptodate, return -EIO.
1825 */
1826struct page *read_cache_page(struct address_space *mapping,
1827 unsigned long index,
1828 int (*filler)(void *,struct page*),
1829 void *data)
1830{
1831 struct page *page;
1832
1833 page = read_cache_page_async(mapping, index, filler, data);
1834 if (IS_ERR(page))
1835 goto out;
1836 wait_on_page_locked(page);
1837 if (!PageUptodate(page)) {
1838 page_cache_release(page);
1839 page = ERR_PTR(-EIO);
1840 }
1841 out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001842 return page;
1843}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844EXPORT_SYMBOL(read_cache_page);
1845
1846/*
1847 * If the page was newly created, increment its refcount and add it to the
1848 * caller's lru-buffering pagevec. This function is specifically for
1849 * generic_file_write().
1850 */
1851static inline struct page *
1852__grab_cache_page(struct address_space *mapping, unsigned long index,
1853 struct page **cached_page, struct pagevec *lru_pvec)
1854{
1855 int err;
1856 struct page *page;
1857repeat:
1858 page = find_lock_page(mapping, index);
1859 if (!page) {
1860 if (!*cached_page) {
1861 *cached_page = page_cache_alloc(mapping);
1862 if (!*cached_page)
1863 return NULL;
1864 }
1865 err = add_to_page_cache(*cached_page, mapping,
1866 index, GFP_KERNEL);
1867 if (err == -EEXIST)
1868 goto repeat;
1869 if (err == 0) {
1870 page = *cached_page;
1871 page_cache_get(page);
1872 if (!pagevec_add(lru_pvec, page))
1873 __pagevec_lru_add(lru_pvec);
1874 *cached_page = NULL;
1875 }
1876 }
1877 return page;
1878}
1879
1880/*
1881 * The logic we want is
1882 *
1883 * if suid or (sgid and xgrp)
1884 * remove privs
1885 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001886int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001887{
1888 mode_t mode = dentry->d_inode->i_mode;
1889 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890
1891 /* suid always must be killed */
1892 if (unlikely(mode & S_ISUID))
1893 kill = ATTR_KILL_SUID;
1894
1895 /*
1896 * sgid without any exec bits is just a mandatory locking mark; leave
1897 * it alone. If some exec bits are set, it's a real sgid; kill it.
1898 */
1899 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1900 kill |= ATTR_KILL_SGID;
1901
Jens Axboe01de85e2006-10-17 19:50:36 +02001902 if (unlikely(kill && !capable(CAP_FSETID)))
1903 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904
Jens Axboe01de85e2006-10-17 19:50:36 +02001905 return 0;
1906}
Mark Fashehd23a1472006-10-17 17:05:18 -07001907EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001908
1909int __remove_suid(struct dentry *dentry, int kill)
1910{
1911 struct iattr newattrs;
1912
1913 newattrs.ia_valid = ATTR_FORCE | kill;
1914 return notify_change(dentry, &newattrs);
1915}
1916
1917int remove_suid(struct dentry *dentry)
1918{
1919 int kill = should_remove_suid(dentry);
1920
1921 if (unlikely(kill))
1922 return __remove_suid(dentry, kill);
1923
1924 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925}
1926EXPORT_SYMBOL(remove_suid);
1927
Carsten Otteceffc072005-06-23 22:05:25 -07001928size_t
NeilBrown01408c42006-06-25 05:47:58 -07001929__filemap_copy_from_user_iovec_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 const struct iovec *iov, size_t base, size_t bytes)
1931{
1932 size_t copied = 0, left = 0;
1933
1934 while (bytes) {
1935 char __user *buf = iov->iov_base + base;
1936 int copy = min(bytes, iov->iov_len - base);
1937
1938 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001939 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940 copied += copy;
1941 bytes -= copy;
1942 vaddr += copy;
1943 iov++;
1944
NeilBrown01408c42006-06-25 05:47:58 -07001945 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947 }
1948 return copied - left;
1949}
1950
1951/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952 * Performs necessary checks before doing a write
1953 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001954 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 * Returns appropriate error code that caller should return or
1956 * zero in case that write should be allowed.
1957 */
1958inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1959{
1960 struct inode *inode = file->f_mapping->host;
1961 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1962
1963 if (unlikely(*pos < 0))
1964 return -EINVAL;
1965
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966 if (!isblk) {
1967 /* FIXME: this is for backwards compatibility with 2.4 */
1968 if (file->f_flags & O_APPEND)
1969 *pos = i_size_read(inode);
1970
1971 if (limit != RLIM_INFINITY) {
1972 if (*pos >= limit) {
1973 send_sig(SIGXFSZ, current, 0);
1974 return -EFBIG;
1975 }
1976 if (*count > limit - (typeof(limit))*pos) {
1977 *count = limit - (typeof(limit))*pos;
1978 }
1979 }
1980 }
1981
1982 /*
1983 * LFS rule
1984 */
1985 if (unlikely(*pos + *count > MAX_NON_LFS &&
1986 !(file->f_flags & O_LARGEFILE))) {
1987 if (*pos >= MAX_NON_LFS) {
1988 send_sig(SIGXFSZ, current, 0);
1989 return -EFBIG;
1990 }
1991 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1992 *count = MAX_NON_LFS - (unsigned long)*pos;
1993 }
1994 }
1995
1996 /*
1997 * Are we about to exceed the fs block limit ?
1998 *
1999 * If we have written data it becomes a short write. If we have
2000 * exceeded without writing data we send a signal and return EFBIG.
2001 * Linus frestrict idea will clean these up nicely..
2002 */
2003 if (likely(!isblk)) {
2004 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2005 if (*count || *pos > inode->i_sb->s_maxbytes) {
2006 send_sig(SIGXFSZ, current, 0);
2007 return -EFBIG;
2008 }
2009 /* zero-length writes at ->s_maxbytes are OK */
2010 }
2011
2012 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2013 *count = inode->i_sb->s_maxbytes - *pos;
2014 } else {
David Howells93614012006-09-30 20:45:40 +02002015#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 loff_t isize;
2017 if (bdev_read_only(I_BDEV(inode)))
2018 return -EPERM;
2019 isize = i_size_read(inode);
2020 if (*pos >= isize) {
2021 if (*count || *pos > isize)
2022 return -ENOSPC;
2023 }
2024
2025 if (*pos + *count > isize)
2026 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002027#else
2028 return -EPERM;
2029#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 }
2031 return 0;
2032}
2033EXPORT_SYMBOL(generic_write_checks);
2034
2035ssize_t
2036generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2037 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2038 size_t count, size_t ocount)
2039{
2040 struct file *file = iocb->ki_filp;
2041 struct address_space *mapping = file->f_mapping;
2042 struct inode *inode = mapping->host;
2043 ssize_t written;
2044
2045 if (count != ocount)
2046 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2047
2048 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2049 if (written > 0) {
2050 loff_t end = pos + written;
2051 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2052 i_size_write(inode, end);
2053 mark_inode_dirty(inode);
2054 }
2055 *ppos = end;
2056 }
2057
2058 /*
2059 * Sync the fs metadata but not the minor inode changes and
2060 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002061 * i_mutex is held, which protects generic_osync_inode() from
Zach Brown8459d862006-12-10 02:21:05 -08002062 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 */
Zach Brown8459d862006-12-10 02:21:05 -08002064 if ((written >= 0 || written == -EIOCBQUEUED) &&
2065 ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07002066 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2067 if (err < 0)
2068 written = err;
2069 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 return written;
2071}
2072EXPORT_SYMBOL(generic_file_direct_write);
2073
2074ssize_t
2075generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2076 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2077 size_t count, ssize_t written)
2078{
2079 struct file *file = iocb->ki_filp;
2080 struct address_space * mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002081 const struct address_space_operations *a_ops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002082 struct inode *inode = mapping->host;
2083 long status = 0;
2084 struct page *page;
2085 struct page *cached_page = NULL;
2086 size_t bytes;
2087 struct pagevec lru_pvec;
2088 const struct iovec *cur_iov = iov; /* current iovec */
2089 size_t iov_base = 0; /* offset in the current iovec */
2090 char __user *buf;
2091
2092 pagevec_init(&lru_pvec, 0);
2093
2094 /*
2095 * handle partial DIO write. Adjust cur_iov if needed.
2096 */
2097 if (likely(nr_segs == 1))
2098 buf = iov->iov_base + written;
2099 else {
2100 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002101 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002102 }
2103
2104 do {
2105 unsigned long index;
2106 unsigned long offset;
2107 size_t copied;
2108
2109 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2110 index = pos >> PAGE_CACHE_SHIFT;
2111 bytes = PAGE_CACHE_SIZE - offset;
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002112
2113 /* Limit the size of the copy to the caller's write size */
2114 bytes = min(bytes, count);
2115
NeilBrown29dbb3f2007-02-16 01:28:38 -08002116 /* We only need to worry about prefaulting when writes are from
2117 * user-space. NFSd uses vfs_writev with several non-aligned
2118 * segments in the vector, and limiting to one segment a time is
2119 * a noticeable performance for re-write
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002120 */
NeilBrown29dbb3f2007-02-16 01:28:38 -08002121 if (!segment_eq(get_fs(), KERNEL_DS)) {
2122 /*
2123 * Limit the size of the copy to that of the current
2124 * segment, because fault_in_pages_readable() doesn't
2125 * know how to walk segments.
2126 */
2127 bytes = min(bytes, cur_iov->iov_len - iov_base);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128
NeilBrown29dbb3f2007-02-16 01:28:38 -08002129 /*
2130 * Bring in the user page that we will copy from
2131 * _first_. Otherwise there's a nasty deadlock on
2132 * copying from the same page as we're writing to,
2133 * without it being marked up-to-date.
2134 */
2135 fault_in_pages_readable(buf, bytes);
2136 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002137 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2138 if (!page) {
2139 status = -ENOMEM;
2140 break;
2141 }
2142
Andrew Morton81b0c872006-06-29 02:24:26 -07002143 if (unlikely(bytes == 0)) {
2144 status = 0;
2145 copied = 0;
2146 goto zero_length_segment;
2147 }
2148
Linus Torvalds1da177e2005-04-16 15:20:36 -07002149 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2150 if (unlikely(status)) {
2151 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08002152
2153 if (status != AOP_TRUNCATED_PAGE)
2154 unlock_page(page);
2155 page_cache_release(page);
2156 if (status == AOP_TRUNCATED_PAGE)
2157 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002158 /*
2159 * prepare_write() may have instantiated a few blocks
2160 * outside i_size. Trim these off again.
2161 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002162 if (pos + bytes > isize)
2163 vmtruncate(inode, isize);
2164 break;
2165 }
2166 if (likely(nr_segs == 1))
2167 copied = filemap_copy_from_user(page, offset,
2168 buf, bytes);
2169 else
2170 copied = filemap_copy_from_user_iovec(page, offset,
2171 cur_iov, iov_base, bytes);
2172 flush_dcache_page(page);
2173 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08002174 if (status == AOP_TRUNCATED_PAGE) {
2175 page_cache_release(page);
2176 continue;
2177 }
Andrew Morton81b0c872006-06-29 02:24:26 -07002178zero_length_segment:
2179 if (likely(copied >= 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180 if (!status)
2181 status = copied;
2182
2183 if (status >= 0) {
2184 written += status;
2185 count -= status;
2186 pos += status;
2187 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002188 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 filemap_set_next_iovec(&cur_iov,
2190 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002191 if (count)
2192 buf = cur_iov->iov_base +
2193 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002194 } else {
2195 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002196 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197 }
2198 }
2199 if (unlikely(copied != bytes))
2200 if (status >= 0)
2201 status = -EFAULT;
2202 unlock_page(page);
2203 mark_page_accessed(page);
2204 page_cache_release(page);
2205 if (status < 0)
2206 break;
2207 balance_dirty_pages_ratelimited(mapping);
2208 cond_resched();
2209 } while (count);
2210 *ppos = pos;
2211
2212 if (cached_page)
2213 page_cache_release(cached_page);
2214
2215 /*
2216 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2217 */
2218 if (likely(status >= 0)) {
2219 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2220 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2221 status = generic_osync_inode(inode, mapping,
2222 OSYNC_METADATA|OSYNC_DATA);
2223 }
2224 }
2225
2226 /*
2227 * If we get here for O_DIRECT writes then we must have fallen through
2228 * to buffered writes (block instantiation inside i_size). So we sync
2229 * the file data here, to try to honour O_DIRECT expectations.
2230 */
2231 if (unlikely(file->f_flags & O_DIRECT) && written)
2232 status = filemap_write_and_wait(mapping);
2233
2234 pagevec_lru_add(&lru_pvec);
2235 return written ? written : status;
2236}
2237EXPORT_SYMBOL(generic_file_buffered_write);
2238
Adrian Bunk5ce78522005-09-10 00:26:28 -07002239static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002240__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2241 unsigned long nr_segs, loff_t *ppos)
2242{
2243 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002244 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 size_t ocount; /* original count */
2246 size_t count; /* after file limit checks */
2247 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 loff_t pos;
2249 ssize_t written;
2250 ssize_t err;
2251
2252 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002253 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2254 if (err)
2255 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256
2257 count = ocount;
2258 pos = *ppos;
2259
2260 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2261
2262 /* We can write back this queue in page reclaim */
2263 current->backing_dev_info = mapping->backing_dev_info;
2264 written = 0;
2265
2266 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2267 if (err)
2268 goto out;
2269
2270 if (count == 0)
2271 goto out;
2272
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002273 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274 if (err)
2275 goto out;
2276
Christoph Hellwig870f4812006-01-09 20:52:01 -08002277 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002278
2279 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2280 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002281 loff_t endbyte;
2282 ssize_t written_buffered;
2283
2284 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2285 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002286 if (written < 0 || written == count)
2287 goto out;
2288 /*
2289 * direct-io write to a hole: fall through to buffered I/O
2290 * for completing the rest of the request.
2291 */
2292 pos += written;
2293 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002294 written_buffered = generic_file_buffered_write(iocb, iov,
2295 nr_segs, pos, ppos, count,
2296 written);
2297 /*
2298 * If generic_file_buffered_write() retuned a synchronous error
2299 * then we want to return the number of bytes which were
2300 * direct-written, or the error code if that was zero. Note
2301 * that this differs from normal direct-io semantics, which
2302 * will return -EFOO even if some bytes were written.
2303 */
2304 if (written_buffered < 0) {
2305 err = written_buffered;
2306 goto out;
2307 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002309 /*
2310 * We need to ensure that the page cache pages are written to
2311 * disk and invalidated to preserve the expected O_DIRECT
2312 * semantics.
2313 */
2314 endbyte = pos + written_buffered - written - 1;
Mark Fashehef51c972007-05-08 00:27:10 -07002315 err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
2316 SYNC_FILE_RANGE_WAIT_BEFORE|
2317 SYNC_FILE_RANGE_WRITE|
2318 SYNC_FILE_RANGE_WAIT_AFTER);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002319 if (err == 0) {
2320 written = written_buffered;
2321 invalidate_mapping_pages(mapping,
2322 pos >> PAGE_CACHE_SHIFT,
2323 endbyte >> PAGE_CACHE_SHIFT);
2324 } else {
2325 /*
2326 * We don't know how much we wrote, so just return
2327 * the number of bytes which were direct-written
2328 */
2329 }
2330 } else {
2331 written = generic_file_buffered_write(iocb, iov, nr_segs,
2332 pos, ppos, count, written);
2333 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334out:
2335 current->backing_dev_info = NULL;
2336 return written ? written : err;
2337}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338
Badari Pulavarty027445c2006-09-30 23:28:46 -07002339ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2340 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002341{
2342 struct file *file = iocb->ki_filp;
2343 struct address_space *mapping = file->f_mapping;
2344 struct inode *inode = mapping->host;
2345 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346
Badari Pulavarty027445c2006-09-30 23:28:46 -07002347 BUG_ON(iocb->ki_pos != pos);
2348
2349 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2350 &iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351
2352 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Badari Pulavarty027445c2006-09-30 23:28:46 -07002353 ssize_t err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354
2355 err = sync_page_range_nolock(inode, mapping, pos, ret);
2356 if (err < 0)
2357 ret = err;
2358 }
2359 return ret;
2360}
Badari Pulavarty027445c2006-09-30 23:28:46 -07002361EXPORT_SYMBOL(generic_file_aio_write_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002362
Badari Pulavarty027445c2006-09-30 23:28:46 -07002363ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2364 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365{
2366 struct file *file = iocb->ki_filp;
2367 struct address_space *mapping = file->f_mapping;
2368 struct inode *inode = mapping->host;
2369 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370
2371 BUG_ON(iocb->ki_pos != pos);
2372
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002373 mutex_lock(&inode->i_mutex);
Badari Pulavarty027445c2006-09-30 23:28:46 -07002374 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2375 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002376 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002377
2378 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2379 ssize_t err;
2380
2381 err = sync_page_range(inode, mapping, pos, ret);
2382 if (err < 0)
2383 ret = err;
2384 }
2385 return ret;
2386}
2387EXPORT_SYMBOL(generic_file_aio_write);
2388
Linus Torvalds1da177e2005-04-16 15:20:36 -07002389/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002390 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002391 * went wrong during pagecache shootdown.
2392 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002393static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002394generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2395 loff_t offset, unsigned long nr_segs)
2396{
2397 struct file *file = iocb->ki_filp;
2398 struct address_space *mapping = file->f_mapping;
2399 ssize_t retval;
Zach Brown65b82912007-03-16 13:38:11 -08002400 size_t write_len;
2401 pgoff_t end = 0; /* silence gcc */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002402
2403 /*
2404 * If it's a write, unmap all mmappings of the file up-front. This
2405 * will cause any pte dirty bits to be propagated into the pageframes
2406 * for the subsequent filemap_write_and_wait().
2407 */
2408 if (rw == WRITE) {
2409 write_len = iov_length(iov, nr_segs);
Zach Brown65b82912007-03-16 13:38:11 -08002410 end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411 if (mapping_mapped(mapping))
2412 unmap_mapping_range(mapping, offset, write_len, 0);
2413 }
2414
2415 retval = filemap_write_and_wait(mapping);
Zach Brown65b82912007-03-16 13:38:11 -08002416 if (retval)
2417 goto out;
2418
2419 /*
2420 * After a write we want buffered reads to be sure to go to disk to get
2421 * the new data. We invalidate clean cached page from the region we're
2422 * about to write. We do this *before* the write so that we can return
2423 * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
2424 */
2425 if (rw == WRITE && mapping->nrpages) {
2426 retval = invalidate_inode_pages2_range(mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 offset >> PAGE_CACHE_SHIFT, end);
Zach Brown65b82912007-03-16 13:38:11 -08002428 if (retval)
2429 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002430 }
Zach Brown65b82912007-03-16 13:38:11 -08002431
2432 retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
2433 if (retval)
2434 goto out;
2435
2436 /*
2437 * Finally, try again to invalidate clean pages which might have been
2438 * faulted in by get_user_pages() if the source of the write was an
2439 * mmap()ed region of the file we're writing. That's a pretty crazy
2440 * thing to do, so we don't support it 100%. If this invalidation
2441 * fails and we have -EIOCBQUEUED we ignore the failure.
2442 */
2443 if (rw == WRITE && mapping->nrpages) {
2444 int err = invalidate_inode_pages2_range(mapping,
2445 offset >> PAGE_CACHE_SHIFT, end);
2446 if (err && retval >= 0)
2447 retval = err;
2448 }
2449out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002450 return retval;
2451}
David Howellscf9a2ae2006-08-29 19:05:54 +01002452
2453/**
2454 * try_to_release_page() - release old fs-specific metadata on a page
2455 *
2456 * @page: the page which the kernel is trying to free
2457 * @gfp_mask: memory allocation flags (and I/O mode)
2458 *
2459 * The address_space is to try to release any data against the page
2460 * (presumably at page->private). If the release was successful, return `1'.
2461 * Otherwise return zero.
2462 *
2463 * The @gfp_mask argument specifies whether I/O may be performed to release
2464 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2465 *
2466 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2467 */
2468int try_to_release_page(struct page *page, gfp_t gfp_mask)
2469{
2470 struct address_space * const mapping = page->mapping;
2471
2472 BUG_ON(!PageLocked(page));
2473 if (PageWriteback(page))
2474 return 0;
2475
2476 if (mapping && mapping->a_ops->releasepage)
2477 return mapping->a_ops->releasepage(page, gfp_mask);
2478 return try_to_free_buffers(page);
2479}
2480
2481EXPORT_SYMBOL(try_to_release_page);