blob: 5dfc093ceb3d680322158f508bed3b0b47a8fbb7 [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) {
673 cached_page = alloc_page(gfp_mask);
674 if (!cached_page)
675 return NULL;
676 }
677 err = add_to_page_cache_lru(cached_page, mapping,
678 index, gfp_mask);
679 if (!err) {
680 page = cached_page;
681 cached_page = NULL;
682 } else if (err == -EEXIST)
683 goto repeat;
684 }
685 if (cached_page)
686 page_cache_release(cached_page);
687 return page;
688}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689EXPORT_SYMBOL(find_or_create_page);
690
691/**
692 * find_get_pages - gang pagecache lookup
693 * @mapping: The address_space to search
694 * @start: The starting page index
695 * @nr_pages: The maximum number of pages
696 * @pages: Where the resulting pages are placed
697 *
698 * find_get_pages() will search for and return a group of up to
699 * @nr_pages pages in the mapping. The pages are placed at @pages.
700 * find_get_pages() takes a reference against the returned pages.
701 *
702 * The search returns a group of mapping-contiguous pages with ascending
703 * indexes. There may be holes in the indices due to not-present pages.
704 *
705 * find_get_pages() returns the number of pages which were found.
706 */
707unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
708 unsigned int nr_pages, struct page **pages)
709{
710 unsigned int i;
711 unsigned int ret;
712
713 read_lock_irq(&mapping->tree_lock);
714 ret = radix_tree_gang_lookup(&mapping->page_tree,
715 (void **)pages, start, nr_pages);
716 for (i = 0; i < ret; i++)
717 page_cache_get(pages[i]);
718 read_unlock_irq(&mapping->tree_lock);
719 return ret;
720}
721
Jens Axboeebf43502006-04-27 08:46:01 +0200722/**
723 * find_get_pages_contig - gang contiguous pagecache lookup
724 * @mapping: The address_space to search
725 * @index: The starting page index
726 * @nr_pages: The maximum number of pages
727 * @pages: Where the resulting pages are placed
728 *
729 * find_get_pages_contig() works exactly like find_get_pages(), except
730 * that the returned number of pages are guaranteed to be contiguous.
731 *
732 * find_get_pages_contig() returns the number of pages which were found.
733 */
734unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
735 unsigned int nr_pages, struct page **pages)
736{
737 unsigned int i;
738 unsigned int ret;
739
740 read_lock_irq(&mapping->tree_lock);
741 ret = radix_tree_gang_lookup(&mapping->page_tree,
742 (void **)pages, index, nr_pages);
743 for (i = 0; i < ret; i++) {
744 if (pages[i]->mapping == NULL || pages[i]->index != index)
745 break;
746
747 page_cache_get(pages[i]);
748 index++;
749 }
750 read_unlock_irq(&mapping->tree_lock);
751 return i;
752}
753
Randy Dunlap485bb992006-06-23 02:03:49 -0700754/**
755 * find_get_pages_tag - find and return pages that match @tag
756 * @mapping: the address_space to search
757 * @index: the starting page index
758 * @tag: the tag index
759 * @nr_pages: the maximum number of pages
760 * @pages: where the resulting pages are placed
761 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700763 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 */
765unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
766 int tag, unsigned int nr_pages, struct page **pages)
767{
768 unsigned int i;
769 unsigned int ret;
770
771 read_lock_irq(&mapping->tree_lock);
772 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
773 (void **)pages, *index, nr_pages, tag);
774 for (i = 0; i < ret; i++)
775 page_cache_get(pages[i]);
776 if (ret)
777 *index = pages[ret - 1]->index + 1;
778 read_unlock_irq(&mapping->tree_lock);
779 return ret;
780}
781
Randy Dunlap485bb992006-06-23 02:03:49 -0700782/**
783 * grab_cache_page_nowait - returns locked page at given index in given cache
784 * @mapping: target address_space
785 * @index: the page index
786 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800787 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 * This is intended for speculative data generators, where the data can
789 * be regenerated if the page couldn't be grabbed. This routine should
790 * be safe to call while holding the lock for another page.
791 *
792 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
793 * and deadlock against the caller's locked page.
794 */
795struct page *
796grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
797{
798 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799
800 if (page) {
801 if (!TestSetPageLocked(page))
802 return page;
803 page_cache_release(page);
804 return NULL;
805 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700806 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
807 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 page_cache_release(page);
809 page = NULL;
810 }
811 return page;
812}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813EXPORT_SYMBOL(grab_cache_page_nowait);
814
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700815/*
816 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
817 * a _large_ part of the i/o request. Imagine the worst scenario:
818 *
819 * ---R__________________________________________B__________
820 * ^ reading here ^ bad block(assume 4k)
821 *
822 * read(R) => miss => readahead(R...B) => media error => frustrating retries
823 * => failing the whole request => read(R) => read(R+1) =>
824 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
825 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
826 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
827 *
828 * It is going insane. Fix it by quickly scaling down the readahead size.
829 */
830static void shrink_readahead_size_eio(struct file *filp,
831 struct file_ra_state *ra)
832{
833 if (!ra->ra_pages)
834 return;
835
836 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700837}
838
Randy Dunlap485bb992006-06-23 02:03:49 -0700839/**
840 * do_generic_mapping_read - generic file read routine
841 * @mapping: address_space to be read
842 * @_ra: file's readahead state
843 * @filp: the file to read
844 * @ppos: current file position
845 * @desc: read_descriptor
846 * @actor: read method
847 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700849 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 *
851 * This is really ugly. But the goto's actually try to clarify some
852 * of the logic when it comes to error handling etc.
853 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700854 * Note the struct file* is only passed for the use of readpage.
855 * It may be NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 */
857void do_generic_mapping_read(struct address_space *mapping,
858 struct file_ra_state *_ra,
859 struct file *filp,
860 loff_t *ppos,
861 read_descriptor_t *desc,
862 read_actor_t actor)
863{
864 struct inode *inode = mapping->host;
865 unsigned long index;
866 unsigned long end_index;
867 unsigned long offset;
868 unsigned long last_index;
869 unsigned long next_index;
870 unsigned long prev_index;
871 loff_t isize;
872 struct page *cached_page;
873 int error;
874 struct file_ra_state ra = *_ra;
875
876 cached_page = NULL;
877 index = *ppos >> PAGE_CACHE_SHIFT;
878 next_index = index;
879 prev_index = ra.prev_page;
880 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
881 offset = *ppos & ~PAGE_CACHE_MASK;
882
883 isize = i_size_read(inode);
884 if (!isize)
885 goto out;
886
887 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
888 for (;;) {
889 struct page *page;
890 unsigned long nr, ret;
891
892 /* nr is the maximum number of bytes to copy from this page */
893 nr = PAGE_CACHE_SIZE;
894 if (index >= end_index) {
895 if (index > end_index)
896 goto out;
897 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
898 if (nr <= offset) {
899 goto out;
900 }
901 }
902 nr = nr - offset;
903
904 cond_resched();
905 if (index == next_index)
906 next_index = page_cache_readahead(mapping, &ra, filp,
907 index, last_index - index);
908
909find_page:
910 page = find_get_page(mapping, index);
911 if (unlikely(page == NULL)) {
912 handle_ra_miss(mapping, &ra, index);
913 goto no_cached_page;
914 }
915 if (!PageUptodate(page))
916 goto page_not_up_to_date;
917page_ok:
918
919 /* If users can be writing to this page using arbitrary
920 * virtual addresses, take care about potential aliasing
921 * before reading the page on the kernel side.
922 */
923 if (mapping_writably_mapped(mapping))
924 flush_dcache_page(page);
925
926 /*
927 * When (part of) the same page is read multiple times
928 * in succession, only mark it as accessed the first time.
929 */
930 if (prev_index != index)
931 mark_page_accessed(page);
932 prev_index = index;
933
934 /*
935 * Ok, we have the page, and it's up-to-date, so
936 * now we can copy it to user space...
937 *
938 * The actor routine returns how many bytes were actually used..
939 * NOTE! This may not be the same as how much of a user buffer
940 * we filled up (we may be padding etc), so we can only update
941 * "pos" here (the actor routine has to update the user buffer
942 * pointers and the remaining count).
943 */
944 ret = actor(desc, page, offset, nr);
945 offset += ret;
946 index += offset >> PAGE_CACHE_SHIFT;
947 offset &= ~PAGE_CACHE_MASK;
948
949 page_cache_release(page);
950 if (ret == nr && desc->count)
951 continue;
952 goto out;
953
954page_not_up_to_date:
955 /* Get exclusive access to the page ... */
956 lock_page(page);
957
Nick Pigginda6052f2006-09-25 23:31:35 -0700958 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 if (!page->mapping) {
960 unlock_page(page);
961 page_cache_release(page);
962 continue;
963 }
964
965 /* Did somebody else fill it already? */
966 if (PageUptodate(page)) {
967 unlock_page(page);
968 goto page_ok;
969 }
970
971readpage:
972 /* Start the actual read. The read will unlock the page. */
973 error = mapping->a_ops->readpage(filp, page);
974
Zach Brown994fc28c2005-12-15 14:28:17 -0800975 if (unlikely(error)) {
976 if (error == AOP_TRUNCATED_PAGE) {
977 page_cache_release(page);
978 goto find_page;
979 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -0800981 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982
983 if (!PageUptodate(page)) {
984 lock_page(page);
985 if (!PageUptodate(page)) {
986 if (page->mapping == NULL) {
987 /*
988 * invalidate_inode_pages got it
989 */
990 unlock_page(page);
991 page_cache_release(page);
992 goto find_page;
993 }
994 unlock_page(page);
995 error = -EIO;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700996 shrink_readahead_size_eio(filp, &ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 goto readpage_error;
998 }
999 unlock_page(page);
1000 }
1001
1002 /*
1003 * i_size must be checked after we have done ->readpage.
1004 *
1005 * Checking i_size after the readpage allows us to calculate
1006 * the correct value for "nr", which means the zero-filled
1007 * part of the page is not copied back to userspace (unless
1008 * another truncate extends the file - this is desired though).
1009 */
1010 isize = i_size_read(inode);
1011 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1012 if (unlikely(!isize || index > end_index)) {
1013 page_cache_release(page);
1014 goto out;
1015 }
1016
1017 /* nr is the maximum number of bytes to copy from this page */
1018 nr = PAGE_CACHE_SIZE;
1019 if (index == end_index) {
1020 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1021 if (nr <= offset) {
1022 page_cache_release(page);
1023 goto out;
1024 }
1025 }
1026 nr = nr - offset;
1027 goto page_ok;
1028
1029readpage_error:
1030 /* UHHUH! A synchronous read error occurred. Report it */
1031 desc->error = error;
1032 page_cache_release(page);
1033 goto out;
1034
1035no_cached_page:
1036 /*
1037 * Ok, it wasn't cached, so we need to create a new
1038 * page..
1039 */
1040 if (!cached_page) {
1041 cached_page = page_cache_alloc_cold(mapping);
1042 if (!cached_page) {
1043 desc->error = -ENOMEM;
1044 goto out;
1045 }
1046 }
1047 error = add_to_page_cache_lru(cached_page, mapping,
1048 index, GFP_KERNEL);
1049 if (error) {
1050 if (error == -EEXIST)
1051 goto find_page;
1052 desc->error = error;
1053 goto out;
1054 }
1055 page = cached_page;
1056 cached_page = NULL;
1057 goto readpage;
1058 }
1059
1060out:
1061 *_ra = ra;
1062
1063 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1064 if (cached_page)
1065 page_cache_release(cached_page);
1066 if (filp)
1067 file_accessed(filp);
1068}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069EXPORT_SYMBOL(do_generic_mapping_read);
1070
1071int file_read_actor(read_descriptor_t *desc, struct page *page,
1072 unsigned long offset, unsigned long size)
1073{
1074 char *kaddr;
1075 unsigned long left, count = desc->count;
1076
1077 if (size > count)
1078 size = count;
1079
1080 /*
1081 * Faults on the destination of a read are common, so do it before
1082 * taking the kmap.
1083 */
1084 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1085 kaddr = kmap_atomic(page, KM_USER0);
1086 left = __copy_to_user_inatomic(desc->arg.buf,
1087 kaddr + offset, size);
1088 kunmap_atomic(kaddr, KM_USER0);
1089 if (left == 0)
1090 goto success;
1091 }
1092
1093 /* Do it the slow way */
1094 kaddr = kmap(page);
1095 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1096 kunmap(page);
1097
1098 if (left) {
1099 size -= left;
1100 desc->error = -EFAULT;
1101 }
1102success:
1103 desc->count = count - size;
1104 desc->written += size;
1105 desc->arg.buf += size;
1106 return size;
1107}
1108
Randy Dunlap485bb992006-06-23 02:03:49 -07001109/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001110 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001111 * @iocb: kernel I/O control block
1112 * @iov: io vector request
1113 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001114 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001115 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 * This is the "read()" routine for all filesystems
1117 * that can use the page cache directly.
1118 */
1119ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001120generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1121 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001122{
1123 struct file *filp = iocb->ki_filp;
1124 ssize_t retval;
1125 unsigned long seg;
1126 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001127 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001128
1129 count = 0;
1130 for (seg = 0; seg < nr_segs; seg++) {
1131 const struct iovec *iv = &iov[seg];
1132
1133 /*
1134 * If any segment has a negative length, or the cumulative
1135 * length ever wraps negative then return -EINVAL.
1136 */
1137 count += iv->iov_len;
1138 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1139 return -EINVAL;
1140 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1141 continue;
1142 if (seg == 0)
1143 return -EFAULT;
1144 nr_segs = seg;
1145 count -= iv->iov_len; /* This segment is no good */
1146 break;
1147 }
1148
1149 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1150 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001151 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152 struct address_space *mapping;
1153 struct inode *inode;
1154
1155 mapping = filp->f_mapping;
1156 inode = mapping->host;
1157 retval = 0;
1158 if (!count)
1159 goto out; /* skip atime */
1160 size = i_size_read(inode);
1161 if (pos < size) {
1162 retval = generic_file_direct_IO(READ, iocb,
1163 iov, pos, nr_segs);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 if (retval > 0)
1165 *ppos = pos + retval;
1166 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001167 if (likely(retval != 0)) {
Steven Whitehouse3f1a9aa2006-09-27 14:52:48 -04001168 file_accessed(filp);
Steven Whitehousea9e5f4d2006-07-25 17:24:12 -04001169 goto out;
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001170 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 }
1172
1173 retval = 0;
1174 if (count) {
1175 for (seg = 0; seg < nr_segs; seg++) {
1176 read_descriptor_t desc;
1177
1178 desc.written = 0;
1179 desc.arg.buf = iov[seg].iov_base;
1180 desc.count = iov[seg].iov_len;
1181 if (desc.count == 0)
1182 continue;
1183 desc.error = 0;
1184 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1185 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001186 if (desc.error) {
1187 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 break;
1189 }
1190 }
1191 }
1192out:
1193 return retval;
1194}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195EXPORT_SYMBOL(generic_file_aio_read);
1196
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1198{
1199 ssize_t written;
1200 unsigned long count = desc->count;
1201 struct file *file = desc->arg.data;
1202
1203 if (size > count)
1204 size = count;
1205
1206 written = file->f_op->sendpage(file, page, offset,
1207 size, &file->f_pos, size<count);
1208 if (written < 0) {
1209 desc->error = written;
1210 written = 0;
1211 }
1212 desc->count = count - written;
1213 desc->written += written;
1214 return written;
1215}
1216
1217ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1218 size_t count, read_actor_t actor, void *target)
1219{
1220 read_descriptor_t desc;
1221
1222 if (!count)
1223 return 0;
1224
1225 desc.written = 0;
1226 desc.count = count;
1227 desc.arg.data = target;
1228 desc.error = 0;
1229
1230 do_generic_file_read(in_file, ppos, &desc, actor);
1231 if (desc.written)
1232 return desc.written;
1233 return desc.error;
1234}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235EXPORT_SYMBOL(generic_file_sendfile);
1236
1237static ssize_t
1238do_readahead(struct address_space *mapping, struct file *filp,
1239 unsigned long index, unsigned long nr)
1240{
1241 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1242 return -EINVAL;
1243
1244 force_page_cache_readahead(mapping, filp, index,
1245 max_sane_readahead(nr));
1246 return 0;
1247}
1248
1249asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1250{
1251 ssize_t ret;
1252 struct file *file;
1253
1254 ret = -EBADF;
1255 file = fget(fd);
1256 if (file) {
1257 if (file->f_mode & FMODE_READ) {
1258 struct address_space *mapping = file->f_mapping;
1259 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1260 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1261 unsigned long len = end - start + 1;
1262 ret = do_readahead(mapping, file, start, len);
1263 }
1264 fput(file);
1265 }
1266 return ret;
1267}
1268
1269#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001270static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1271/**
1272 * page_cache_read - adds requested page to the page cache if not already there
1273 * @file: file to read
1274 * @offset: page index
1275 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 * This adds the requested page to the page cache if it isn't already there,
1277 * and schedules an I/O to read in its contents from disk.
1278 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279static int fastcall page_cache_read(struct file * file, unsigned long offset)
1280{
1281 struct address_space *mapping = file->f_mapping;
1282 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001283 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
Zach Brown994fc28c2005-12-15 14:28:17 -08001285 do {
1286 page = page_cache_alloc_cold(mapping);
1287 if (!page)
1288 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
Zach Brown994fc28c2005-12-15 14:28:17 -08001290 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1291 if (ret == 0)
1292 ret = mapping->a_ops->readpage(file, page);
1293 else if (ret == -EEXIST)
1294 ret = 0; /* losing race to add is OK */
1295
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297
Zach Brown994fc28c2005-12-15 14:28:17 -08001298 } while (ret == AOP_TRUNCATED_PAGE);
1299
1300 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301}
1302
1303#define MMAP_LOTSAMISS (100)
1304
Randy Dunlap485bb992006-06-23 02:03:49 -07001305/**
1306 * filemap_nopage - read in file data for page fault handling
1307 * @area: the applicable vm_area
1308 * @address: target address to read in
1309 * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1310 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 * filemap_nopage() is invoked via the vma operations vector for a
1312 * mapped memory region to read in file data during a page fault.
1313 *
1314 * The goto's are kind of ugly, but this streamlines the normal case of having
1315 * it in the page cache, and handles the special cases reasonably without
1316 * having a lot of duplicated code.
1317 */
1318struct page *filemap_nopage(struct vm_area_struct *area,
1319 unsigned long address, int *type)
1320{
1321 int error;
1322 struct file *file = area->vm_file;
1323 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;
1327 unsigned long size, pgoff;
1328 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1329
1330 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1331
1332retry_all:
1333 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1334 if (pgoff >= size)
1335 goto outside_data_content;
1336
1337 /* If we don't want any read-ahead, don't bother */
1338 if (VM_RandomReadHint(area))
1339 goto no_cached_page;
1340
1341 /*
1342 * The readahead code wants to be told about each and every page
1343 * so it can build and shrink its windows appropriately
1344 *
1345 * For sequential accesses, we use the generic readahead logic.
1346 */
1347 if (VM_SequentialReadHint(area))
1348 page_cache_readahead(mapping, ra, file, pgoff, 1);
1349
1350 /*
1351 * Do we have something in the page cache already?
1352 */
1353retry_find:
1354 page = find_get_page(mapping, pgoff);
1355 if (!page) {
1356 unsigned long ra_pages;
1357
1358 if (VM_SequentialReadHint(area)) {
1359 handle_ra_miss(mapping, ra, pgoff);
1360 goto no_cached_page;
1361 }
1362 ra->mmap_miss++;
1363
1364 /*
1365 * Do we miss much more than hit in this file? If so,
1366 * stop bothering with read-ahead. It will only hurt.
1367 */
1368 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1369 goto no_cached_page;
1370
1371 /*
1372 * To keep the pgmajfault counter straight, we need to
1373 * check did_readaround, as this is an inner loop.
1374 */
1375 if (!did_readaround) {
1376 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001377 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 }
1379 did_readaround = 1;
1380 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1381 if (ra_pages) {
1382 pgoff_t start = 0;
1383
1384 if (pgoff > ra_pages / 2)
1385 start = pgoff - ra_pages / 2;
1386 do_page_cache_readahead(mapping, file, start, ra_pages);
1387 }
1388 page = find_get_page(mapping, pgoff);
1389 if (!page)
1390 goto no_cached_page;
1391 }
1392
1393 if (!did_readaround)
1394 ra->mmap_hit++;
1395
1396 /*
1397 * Ok, found a page in the page cache, now we need to check
1398 * that it's up-to-date.
1399 */
1400 if (!PageUptodate(page))
1401 goto page_not_uptodate;
1402
1403success:
1404 /*
1405 * Found the page and have a reference on it.
1406 */
1407 mark_page_accessed(page);
1408 if (type)
1409 *type = majmin;
1410 return page;
1411
1412outside_data_content:
1413 /*
1414 * An external ptracer can access pages that normally aren't
1415 * accessible..
1416 */
1417 if (area->vm_mm == current->mm)
Adam Litke79f5acf2006-09-29 01:58:43 -07001418 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 /* Fall through to the non-read-ahead case */
1420no_cached_page:
1421 /*
1422 * We're only likely to ever get here if MADV_RANDOM is in
1423 * effect.
1424 */
1425 error = page_cache_read(file, pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426
1427 /*
1428 * The page we want has now been added to the page cache.
1429 * In the unlikely event that someone removed it in the
1430 * meantime, we'll just come back here and read it again.
1431 */
1432 if (error >= 0)
1433 goto retry_find;
1434
1435 /*
1436 * An error return from page_cache_read can result if the
1437 * system is low on memory, or a problem occurs while trying
1438 * to schedule I/O.
1439 */
1440 if (error == -ENOMEM)
1441 return NOPAGE_OOM;
Adam Litke79f5acf2006-09-29 01:58:43 -07001442 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443
1444page_not_uptodate:
1445 if (!did_readaround) {
1446 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001447 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448 }
1449 lock_page(page);
1450
1451 /* Did it get unhashed while we waited for it? */
1452 if (!page->mapping) {
1453 unlock_page(page);
1454 page_cache_release(page);
1455 goto retry_all;
1456 }
1457
1458 /* Did somebody else get it up-to-date? */
1459 if (PageUptodate(page)) {
1460 unlock_page(page);
1461 goto success;
1462 }
1463
Zach Brown994fc28c2005-12-15 14:28:17 -08001464 error = mapping->a_ops->readpage(file, page);
1465 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 wait_on_page_locked(page);
1467 if (PageUptodate(page))
1468 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001469 } else if (error == AOP_TRUNCATED_PAGE) {
1470 page_cache_release(page);
1471 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 }
1473
1474 /*
1475 * Umm, take care of errors if the page isn't up-to-date.
1476 * Try to re-read it _once_. We do this synchronously,
1477 * because there really aren't any performance issues here
1478 * and we need to check for errors.
1479 */
1480 lock_page(page);
1481
1482 /* Somebody truncated the page on us? */
1483 if (!page->mapping) {
1484 unlock_page(page);
1485 page_cache_release(page);
1486 goto retry_all;
1487 }
1488
1489 /* Somebody else successfully read it in? */
1490 if (PageUptodate(page)) {
1491 unlock_page(page);
1492 goto success;
1493 }
1494 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001495 error = mapping->a_ops->readpage(file, page);
1496 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 wait_on_page_locked(page);
1498 if (PageUptodate(page))
1499 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001500 } else if (error == AOP_TRUNCATED_PAGE) {
1501 page_cache_release(page);
1502 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503 }
1504
1505 /*
1506 * Things didn't work out. Return zero to tell the
1507 * mm layer so, possibly freeing the page cache page first.
1508 */
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001509 shrink_readahead_size_eio(file, ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 page_cache_release(page);
Adam Litke79f5acf2006-09-29 01:58:43 -07001511 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513EXPORT_SYMBOL(filemap_nopage);
1514
1515static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1516 int nonblock)
1517{
1518 struct address_space *mapping = file->f_mapping;
1519 struct page *page;
1520 int error;
1521
1522 /*
1523 * Do we have something in the page cache already?
1524 */
1525retry_find:
1526 page = find_get_page(mapping, pgoff);
1527 if (!page) {
1528 if (nonblock)
1529 return NULL;
1530 goto no_cached_page;
1531 }
1532
1533 /*
1534 * Ok, found a page in the page cache, now we need to check
1535 * that it's up-to-date.
1536 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001537 if (!PageUptodate(page)) {
1538 if (nonblock) {
1539 page_cache_release(page);
1540 return NULL;
1541 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001543 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544
1545success:
1546 /*
1547 * Found the page and have a reference on it.
1548 */
1549 mark_page_accessed(page);
1550 return page;
1551
1552no_cached_page:
1553 error = page_cache_read(file, pgoff);
1554
1555 /*
1556 * The page we want has now been added to the page cache.
1557 * In the unlikely event that someone removed it in the
1558 * meantime, we'll just come back here and read it again.
1559 */
1560 if (error >= 0)
1561 goto retry_find;
1562
1563 /*
1564 * An error return from page_cache_read can result if the
1565 * system is low on memory, or a problem occurs while trying
1566 * to schedule I/O.
1567 */
1568 return NULL;
1569
1570page_not_uptodate:
1571 lock_page(page);
1572
Nick Pigginda6052f2006-09-25 23:31:35 -07001573 /* Did it get truncated while we waited for it? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 if (!page->mapping) {
1575 unlock_page(page);
1576 goto err;
1577 }
1578
1579 /* Did somebody else get it up-to-date? */
1580 if (PageUptodate(page)) {
1581 unlock_page(page);
1582 goto success;
1583 }
1584
Zach Brown994fc28c2005-12-15 14:28:17 -08001585 error = mapping->a_ops->readpage(file, page);
1586 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 wait_on_page_locked(page);
1588 if (PageUptodate(page))
1589 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001590 } else if (error == AOP_TRUNCATED_PAGE) {
1591 page_cache_release(page);
1592 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 }
1594
1595 /*
1596 * Umm, take care of errors if the page isn't up-to-date.
1597 * Try to re-read it _once_. We do this synchronously,
1598 * because there really aren't any performance issues here
1599 * and we need to check for errors.
1600 */
1601 lock_page(page);
1602
1603 /* Somebody truncated the page on us? */
1604 if (!page->mapping) {
1605 unlock_page(page);
1606 goto err;
1607 }
1608 /* Somebody else successfully read it in? */
1609 if (PageUptodate(page)) {
1610 unlock_page(page);
1611 goto success;
1612 }
1613
1614 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001615 error = mapping->a_ops->readpage(file, page);
1616 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 wait_on_page_locked(page);
1618 if (PageUptodate(page))
1619 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001620 } else if (error == AOP_TRUNCATED_PAGE) {
1621 page_cache_release(page);
1622 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 }
1624
1625 /*
1626 * Things didn't work out. Return zero to tell the
1627 * mm layer so, possibly freeing the page cache page first.
1628 */
1629err:
1630 page_cache_release(page);
1631
1632 return NULL;
1633}
1634
1635int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1636 unsigned long len, pgprot_t prot, unsigned long pgoff,
1637 int nonblock)
1638{
1639 struct file *file = vma->vm_file;
1640 struct address_space *mapping = file->f_mapping;
1641 struct inode *inode = mapping->host;
1642 unsigned long size;
1643 struct mm_struct *mm = vma->vm_mm;
1644 struct page *page;
1645 int err;
1646
1647 if (!nonblock)
1648 force_page_cache_readahead(mapping, vma->vm_file,
1649 pgoff, len >> PAGE_CACHE_SHIFT);
1650
1651repeat:
1652 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1653 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1654 return -EINVAL;
1655
1656 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001657
1658 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1659 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 if (!page && !nonblock)
1661 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001662
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 if (page) {
1664 err = install_page(mm, vma, addr, page, prot);
1665 if (err) {
1666 page_cache_release(page);
1667 return err;
1668 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001669 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001670 /* No page was found just because we can't read it in now (being
1671 * here implies nonblock != 0), but the page may exist, so set
1672 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 err = install_file_pte(mm, vma, addr, pgoff, prot);
1674 if (err)
1675 return err;
1676 }
1677
1678 len -= PAGE_SIZE;
1679 addr += PAGE_SIZE;
1680 pgoff++;
1681 if (len)
1682 goto repeat;
1683
1684 return 0;
1685}
Nikita Danilovb1459462005-10-29 18:17:02 -07001686EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687
1688struct vm_operations_struct generic_file_vm_ops = {
1689 .nopage = filemap_nopage,
1690 .populate = filemap_populate,
1691};
1692
1693/* This is used for a general mmap of a disk file */
1694
1695int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1696{
1697 struct address_space *mapping = file->f_mapping;
1698
1699 if (!mapping->a_ops->readpage)
1700 return -ENOEXEC;
1701 file_accessed(file);
1702 vma->vm_ops = &generic_file_vm_ops;
1703 return 0;
1704}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705
1706/*
1707 * This is for filesystems which do not implement ->writepage.
1708 */
1709int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1710{
1711 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1712 return -EINVAL;
1713 return generic_file_mmap(file, vma);
1714}
1715#else
1716int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1717{
1718 return -ENOSYS;
1719}
1720int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1721{
1722 return -ENOSYS;
1723}
1724#endif /* CONFIG_MMU */
1725
1726EXPORT_SYMBOL(generic_file_mmap);
1727EXPORT_SYMBOL(generic_file_readonly_mmap);
1728
1729static inline struct page *__read_cache_page(struct address_space *mapping,
1730 unsigned long index,
1731 int (*filler)(void *,struct page*),
1732 void *data)
1733{
1734 struct page *page, *cached_page = NULL;
1735 int err;
1736repeat:
1737 page = find_get_page(mapping, index);
1738 if (!page) {
1739 if (!cached_page) {
1740 cached_page = page_cache_alloc_cold(mapping);
1741 if (!cached_page)
1742 return ERR_PTR(-ENOMEM);
1743 }
1744 err = add_to_page_cache_lru(cached_page, mapping,
1745 index, GFP_KERNEL);
1746 if (err == -EEXIST)
1747 goto repeat;
1748 if (err < 0) {
1749 /* Presumably ENOMEM for radix tree node */
1750 page_cache_release(cached_page);
1751 return ERR_PTR(err);
1752 }
1753 page = cached_page;
1754 cached_page = NULL;
1755 err = filler(data, page);
1756 if (err < 0) {
1757 page_cache_release(page);
1758 page = ERR_PTR(err);
1759 }
1760 }
1761 if (cached_page)
1762 page_cache_release(cached_page);
1763 return page;
1764}
1765
Randy Dunlap485bb992006-06-23 02:03:49 -07001766/**
1767 * read_cache_page - read into page cache, fill it if needed
1768 * @mapping: the page's address_space
1769 * @index: the page index
1770 * @filler: function to perform the read
1771 * @data: destination for read data
1772 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773 * Read into the page cache. If a page already exists,
1774 * and PageUptodate() is not set, try to fill the page.
1775 */
1776struct page *read_cache_page(struct address_space *mapping,
1777 unsigned long index,
1778 int (*filler)(void *,struct page*),
1779 void *data)
1780{
1781 struct page *page;
1782 int err;
1783
1784retry:
1785 page = __read_cache_page(mapping, index, filler, data);
1786 if (IS_ERR(page))
1787 goto out;
1788 mark_page_accessed(page);
1789 if (PageUptodate(page))
1790 goto out;
1791
1792 lock_page(page);
1793 if (!page->mapping) {
1794 unlock_page(page);
1795 page_cache_release(page);
1796 goto retry;
1797 }
1798 if (PageUptodate(page)) {
1799 unlock_page(page);
1800 goto out;
1801 }
1802 err = filler(data, page);
1803 if (err < 0) {
1804 page_cache_release(page);
1805 page = ERR_PTR(err);
1806 }
1807 out:
1808 return page;
1809}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810EXPORT_SYMBOL(read_cache_page);
1811
1812/*
1813 * If the page was newly created, increment its refcount and add it to the
1814 * caller's lru-buffering pagevec. This function is specifically for
1815 * generic_file_write().
1816 */
1817static inline struct page *
1818__grab_cache_page(struct address_space *mapping, unsigned long index,
1819 struct page **cached_page, struct pagevec *lru_pvec)
1820{
1821 int err;
1822 struct page *page;
1823repeat:
1824 page = find_lock_page(mapping, index);
1825 if (!page) {
1826 if (!*cached_page) {
1827 *cached_page = page_cache_alloc(mapping);
1828 if (!*cached_page)
1829 return NULL;
1830 }
1831 err = add_to_page_cache(*cached_page, mapping,
1832 index, GFP_KERNEL);
1833 if (err == -EEXIST)
1834 goto repeat;
1835 if (err == 0) {
1836 page = *cached_page;
1837 page_cache_get(page);
1838 if (!pagevec_add(lru_pvec, page))
1839 __pagevec_lru_add(lru_pvec);
1840 *cached_page = NULL;
1841 }
1842 }
1843 return page;
1844}
1845
1846/*
1847 * The logic we want is
1848 *
1849 * if suid or (sgid and xgrp)
1850 * remove privs
1851 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001852int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853{
1854 mode_t mode = dentry->d_inode->i_mode;
1855 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856
1857 /* suid always must be killed */
1858 if (unlikely(mode & S_ISUID))
1859 kill = ATTR_KILL_SUID;
1860
1861 /*
1862 * sgid without any exec bits is just a mandatory locking mark; leave
1863 * it alone. If some exec bits are set, it's a real sgid; kill it.
1864 */
1865 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1866 kill |= ATTR_KILL_SGID;
1867
Jens Axboe01de85e2006-10-17 19:50:36 +02001868 if (unlikely(kill && !capable(CAP_FSETID)))
1869 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870
Jens Axboe01de85e2006-10-17 19:50:36 +02001871 return 0;
1872}
Mark Fashehd23a1472006-10-17 17:05:18 -07001873EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001874
1875int __remove_suid(struct dentry *dentry, int kill)
1876{
1877 struct iattr newattrs;
1878
1879 newattrs.ia_valid = ATTR_FORCE | kill;
1880 return notify_change(dentry, &newattrs);
1881}
1882
1883int remove_suid(struct dentry *dentry)
1884{
1885 int kill = should_remove_suid(dentry);
1886
1887 if (unlikely(kill))
1888 return __remove_suid(dentry, kill);
1889
1890 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891}
1892EXPORT_SYMBOL(remove_suid);
1893
Carsten Otteceffc072005-06-23 22:05:25 -07001894size_t
NeilBrown01408c42006-06-25 05:47:58 -07001895__filemap_copy_from_user_iovec_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896 const struct iovec *iov, size_t base, size_t bytes)
1897{
1898 size_t copied = 0, left = 0;
1899
1900 while (bytes) {
1901 char __user *buf = iov->iov_base + base;
1902 int copy = min(bytes, iov->iov_len - base);
1903
1904 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001905 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906 copied += copy;
1907 bytes -= copy;
1908 vaddr += copy;
1909 iov++;
1910
NeilBrown01408c42006-06-25 05:47:58 -07001911 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 }
1914 return copied - left;
1915}
1916
1917/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 * Performs necessary checks before doing a write
1919 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001920 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001921 * Returns appropriate error code that caller should return or
1922 * zero in case that write should be allowed.
1923 */
1924inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1925{
1926 struct inode *inode = file->f_mapping->host;
1927 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1928
1929 if (unlikely(*pos < 0))
1930 return -EINVAL;
1931
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 if (!isblk) {
1933 /* FIXME: this is for backwards compatibility with 2.4 */
1934 if (file->f_flags & O_APPEND)
1935 *pos = i_size_read(inode);
1936
1937 if (limit != RLIM_INFINITY) {
1938 if (*pos >= limit) {
1939 send_sig(SIGXFSZ, current, 0);
1940 return -EFBIG;
1941 }
1942 if (*count > limit - (typeof(limit))*pos) {
1943 *count = limit - (typeof(limit))*pos;
1944 }
1945 }
1946 }
1947
1948 /*
1949 * LFS rule
1950 */
1951 if (unlikely(*pos + *count > MAX_NON_LFS &&
1952 !(file->f_flags & O_LARGEFILE))) {
1953 if (*pos >= MAX_NON_LFS) {
1954 send_sig(SIGXFSZ, current, 0);
1955 return -EFBIG;
1956 }
1957 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1958 *count = MAX_NON_LFS - (unsigned long)*pos;
1959 }
1960 }
1961
1962 /*
1963 * Are we about to exceed the fs block limit ?
1964 *
1965 * If we have written data it becomes a short write. If we have
1966 * exceeded without writing data we send a signal and return EFBIG.
1967 * Linus frestrict idea will clean these up nicely..
1968 */
1969 if (likely(!isblk)) {
1970 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1971 if (*count || *pos > inode->i_sb->s_maxbytes) {
1972 send_sig(SIGXFSZ, current, 0);
1973 return -EFBIG;
1974 }
1975 /* zero-length writes at ->s_maxbytes are OK */
1976 }
1977
1978 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1979 *count = inode->i_sb->s_maxbytes - *pos;
1980 } else {
David Howells93614012006-09-30 20:45:40 +02001981#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 loff_t isize;
1983 if (bdev_read_only(I_BDEV(inode)))
1984 return -EPERM;
1985 isize = i_size_read(inode);
1986 if (*pos >= isize) {
1987 if (*count || *pos > isize)
1988 return -ENOSPC;
1989 }
1990
1991 if (*pos + *count > isize)
1992 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02001993#else
1994 return -EPERM;
1995#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996 }
1997 return 0;
1998}
1999EXPORT_SYMBOL(generic_write_checks);
2000
2001ssize_t
2002generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2003 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2004 size_t count, size_t ocount)
2005{
2006 struct file *file = iocb->ki_filp;
2007 struct address_space *mapping = file->f_mapping;
2008 struct inode *inode = mapping->host;
2009 ssize_t written;
2010
2011 if (count != ocount)
2012 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2013
2014 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2015 if (written > 0) {
2016 loff_t end = pos + written;
2017 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2018 i_size_write(inode, end);
2019 mark_inode_dirty(inode);
2020 }
2021 *ppos = end;
2022 }
2023
2024 /*
2025 * Sync the fs metadata but not the minor inode changes and
2026 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002027 * i_mutex is held, which protects generic_osync_inode() from
Zach Brown8459d862006-12-10 02:21:05 -08002028 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002029 */
Zach Brown8459d862006-12-10 02:21:05 -08002030 if ((written >= 0 || written == -EIOCBQUEUED) &&
2031 ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07002032 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2033 if (err < 0)
2034 written = err;
2035 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036 return written;
2037}
2038EXPORT_SYMBOL(generic_file_direct_write);
2039
2040ssize_t
2041generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2042 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2043 size_t count, ssize_t written)
2044{
2045 struct file *file = iocb->ki_filp;
2046 struct address_space * mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002047 const struct address_space_operations *a_ops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048 struct inode *inode = mapping->host;
2049 long status = 0;
2050 struct page *page;
2051 struct page *cached_page = NULL;
2052 size_t bytes;
2053 struct pagevec lru_pvec;
2054 const struct iovec *cur_iov = iov; /* current iovec */
2055 size_t iov_base = 0; /* offset in the current iovec */
2056 char __user *buf;
2057
2058 pagevec_init(&lru_pvec, 0);
2059
2060 /*
2061 * handle partial DIO write. Adjust cur_iov if needed.
2062 */
2063 if (likely(nr_segs == 1))
2064 buf = iov->iov_base + written;
2065 else {
2066 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002067 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068 }
2069
2070 do {
2071 unsigned long index;
2072 unsigned long offset;
2073 size_t copied;
2074
2075 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2076 index = pos >> PAGE_CACHE_SHIFT;
2077 bytes = PAGE_CACHE_SIZE - offset;
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002078
2079 /* Limit the size of the copy to the caller's write size */
2080 bytes = min(bytes, count);
2081
NeilBrown29dbb3f2007-02-16 01:28:38 -08002082 /* We only need to worry about prefaulting when writes are from
2083 * user-space. NFSd uses vfs_writev with several non-aligned
2084 * segments in the vector, and limiting to one segment a time is
2085 * a noticeable performance for re-write
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002086 */
NeilBrown29dbb3f2007-02-16 01:28:38 -08002087 if (!segment_eq(get_fs(), KERNEL_DS)) {
2088 /*
2089 * Limit the size of the copy to that of the current
2090 * segment, because fault_in_pages_readable() doesn't
2091 * know how to walk segments.
2092 */
2093 bytes = min(bytes, cur_iov->iov_len - iov_base);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094
NeilBrown29dbb3f2007-02-16 01:28:38 -08002095 /*
2096 * Bring in the user page that we will copy from
2097 * _first_. Otherwise there's a nasty deadlock on
2098 * copying from the same page as we're writing to,
2099 * without it being marked up-to-date.
2100 */
2101 fault_in_pages_readable(buf, bytes);
2102 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2104 if (!page) {
2105 status = -ENOMEM;
2106 break;
2107 }
2108
Andrew Morton81b0c872006-06-29 02:24:26 -07002109 if (unlikely(bytes == 0)) {
2110 status = 0;
2111 copied = 0;
2112 goto zero_length_segment;
2113 }
2114
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2116 if (unlikely(status)) {
2117 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08002118
2119 if (status != AOP_TRUNCATED_PAGE)
2120 unlock_page(page);
2121 page_cache_release(page);
2122 if (status == AOP_TRUNCATED_PAGE)
2123 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124 /*
2125 * prepare_write() may have instantiated a few blocks
2126 * outside i_size. Trim these off again.
2127 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128 if (pos + bytes > isize)
2129 vmtruncate(inode, isize);
2130 break;
2131 }
2132 if (likely(nr_segs == 1))
2133 copied = filemap_copy_from_user(page, offset,
2134 buf, bytes);
2135 else
2136 copied = filemap_copy_from_user_iovec(page, offset,
2137 cur_iov, iov_base, bytes);
2138 flush_dcache_page(page);
2139 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08002140 if (status == AOP_TRUNCATED_PAGE) {
2141 page_cache_release(page);
2142 continue;
2143 }
Andrew Morton81b0c872006-06-29 02:24:26 -07002144zero_length_segment:
2145 if (likely(copied >= 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 if (!status)
2147 status = copied;
2148
2149 if (status >= 0) {
2150 written += status;
2151 count -= status;
2152 pos += status;
2153 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002154 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 filemap_set_next_iovec(&cur_iov,
2156 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002157 if (count)
2158 buf = cur_iov->iov_base +
2159 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002160 } else {
2161 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002162 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 }
2164 }
2165 if (unlikely(copied != bytes))
2166 if (status >= 0)
2167 status = -EFAULT;
2168 unlock_page(page);
2169 mark_page_accessed(page);
2170 page_cache_release(page);
2171 if (status < 0)
2172 break;
2173 balance_dirty_pages_ratelimited(mapping);
2174 cond_resched();
2175 } while (count);
2176 *ppos = pos;
2177
2178 if (cached_page)
2179 page_cache_release(cached_page);
2180
2181 /*
2182 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2183 */
2184 if (likely(status >= 0)) {
2185 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2186 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2187 status = generic_osync_inode(inode, mapping,
2188 OSYNC_METADATA|OSYNC_DATA);
2189 }
2190 }
2191
2192 /*
2193 * If we get here for O_DIRECT writes then we must have fallen through
2194 * to buffered writes (block instantiation inside i_size). So we sync
2195 * the file data here, to try to honour O_DIRECT expectations.
2196 */
2197 if (unlikely(file->f_flags & O_DIRECT) && written)
2198 status = filemap_write_and_wait(mapping);
2199
2200 pagevec_lru_add(&lru_pvec);
2201 return written ? written : status;
2202}
2203EXPORT_SYMBOL(generic_file_buffered_write);
2204
Adrian Bunk5ce78522005-09-10 00:26:28 -07002205static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2207 unsigned long nr_segs, loff_t *ppos)
2208{
2209 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002210 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002211 size_t ocount; /* original count */
2212 size_t count; /* after file limit checks */
2213 struct inode *inode = mapping->host;
2214 unsigned long seg;
2215 loff_t pos;
2216 ssize_t written;
2217 ssize_t err;
2218
2219 ocount = 0;
2220 for (seg = 0; seg < nr_segs; seg++) {
2221 const struct iovec *iv = &iov[seg];
2222
2223 /*
2224 * If any segment has a negative length, or the cumulative
2225 * length ever wraps negative then return -EINVAL.
2226 */
2227 ocount += iv->iov_len;
2228 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2229 return -EINVAL;
2230 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2231 continue;
2232 if (seg == 0)
2233 return -EFAULT;
2234 nr_segs = seg;
2235 ocount -= iv->iov_len; /* This segment is no good */
2236 break;
2237 }
2238
2239 count = ocount;
2240 pos = *ppos;
2241
2242 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2243
2244 /* We can write back this queue in page reclaim */
2245 current->backing_dev_info = mapping->backing_dev_info;
2246 written = 0;
2247
2248 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2249 if (err)
2250 goto out;
2251
2252 if (count == 0)
2253 goto out;
2254
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002255 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256 if (err)
2257 goto out;
2258
Christoph Hellwig870f4812006-01-09 20:52:01 -08002259 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260
2261 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2262 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002263 loff_t endbyte;
2264 ssize_t written_buffered;
2265
2266 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2267 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268 if (written < 0 || written == count)
2269 goto out;
2270 /*
2271 * direct-io write to a hole: fall through to buffered I/O
2272 * for completing the rest of the request.
2273 */
2274 pos += written;
2275 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002276 written_buffered = generic_file_buffered_write(iocb, iov,
2277 nr_segs, pos, ppos, count,
2278 written);
2279 /*
2280 * If generic_file_buffered_write() retuned a synchronous error
2281 * then we want to return the number of bytes which were
2282 * direct-written, or the error code if that was zero. Note
2283 * that this differs from normal direct-io semantics, which
2284 * will return -EFOO even if some bytes were written.
2285 */
2286 if (written_buffered < 0) {
2287 err = written_buffered;
2288 goto out;
2289 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002290
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002291 /*
2292 * We need to ensure that the page cache pages are written to
2293 * disk and invalidated to preserve the expected O_DIRECT
2294 * semantics.
2295 */
2296 endbyte = pos + written_buffered - written - 1;
2297 err = do_sync_file_range(file, pos, endbyte,
2298 SYNC_FILE_RANGE_WAIT_BEFORE|
2299 SYNC_FILE_RANGE_WRITE|
2300 SYNC_FILE_RANGE_WAIT_AFTER);
2301 if (err == 0) {
2302 written = written_buffered;
2303 invalidate_mapping_pages(mapping,
2304 pos >> PAGE_CACHE_SHIFT,
2305 endbyte >> PAGE_CACHE_SHIFT);
2306 } else {
2307 /*
2308 * We don't know how much we wrote, so just return
2309 * the number of bytes which were direct-written
2310 */
2311 }
2312 } else {
2313 written = generic_file_buffered_write(iocb, iov, nr_segs,
2314 pos, ppos, count, written);
2315 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316out:
2317 current->backing_dev_info = NULL;
2318 return written ? written : err;
2319}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002320
Badari Pulavarty027445c2006-09-30 23:28:46 -07002321ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2322 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323{
2324 struct file *file = iocb->ki_filp;
2325 struct address_space *mapping = file->f_mapping;
2326 struct inode *inode = mapping->host;
2327 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328
Badari Pulavarty027445c2006-09-30 23:28:46 -07002329 BUG_ON(iocb->ki_pos != pos);
2330
2331 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2332 &iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333
2334 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Badari Pulavarty027445c2006-09-30 23:28:46 -07002335 ssize_t err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336
2337 err = sync_page_range_nolock(inode, mapping, pos, ret);
2338 if (err < 0)
2339 ret = err;
2340 }
2341 return ret;
2342}
Badari Pulavarty027445c2006-09-30 23:28:46 -07002343EXPORT_SYMBOL(generic_file_aio_write_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002344
Badari Pulavarty027445c2006-09-30 23:28:46 -07002345ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2346 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347{
2348 struct file *file = iocb->ki_filp;
2349 struct address_space *mapping = file->f_mapping;
2350 struct inode *inode = mapping->host;
2351 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352
2353 BUG_ON(iocb->ki_pos != pos);
2354
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002355 mutex_lock(&inode->i_mutex);
Badari Pulavarty027445c2006-09-30 23:28:46 -07002356 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2357 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002358 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359
2360 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2361 ssize_t err;
2362
2363 err = sync_page_range(inode, mapping, pos, ret);
2364 if (err < 0)
2365 ret = err;
2366 }
2367 return ret;
2368}
2369EXPORT_SYMBOL(generic_file_aio_write);
2370
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002372 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373 * went wrong during pagecache shootdown.
2374 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002375static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2377 loff_t offset, unsigned long nr_segs)
2378{
2379 struct file *file = iocb->ki_filp;
2380 struct address_space *mapping = file->f_mapping;
2381 ssize_t retval;
Zach Brown65b82912007-03-16 13:38:11 -08002382 size_t write_len;
2383 pgoff_t end = 0; /* silence gcc */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384
2385 /*
2386 * If it's a write, unmap all mmappings of the file up-front. This
2387 * will cause any pte dirty bits to be propagated into the pageframes
2388 * for the subsequent filemap_write_and_wait().
2389 */
2390 if (rw == WRITE) {
2391 write_len = iov_length(iov, nr_segs);
Zach Brown65b82912007-03-16 13:38:11 -08002392 end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393 if (mapping_mapped(mapping))
2394 unmap_mapping_range(mapping, offset, write_len, 0);
2395 }
2396
2397 retval = filemap_write_and_wait(mapping);
Zach Brown65b82912007-03-16 13:38:11 -08002398 if (retval)
2399 goto out;
2400
2401 /*
2402 * After a write we want buffered reads to be sure to go to disk to get
2403 * the new data. We invalidate clean cached page from the region we're
2404 * about to write. We do this *before* the write so that we can return
2405 * -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
2406 */
2407 if (rw == WRITE && mapping->nrpages) {
2408 retval = invalidate_inode_pages2_range(mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409 offset >> PAGE_CACHE_SHIFT, end);
Zach Brown65b82912007-03-16 13:38:11 -08002410 if (retval)
2411 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002412 }
Zach Brown65b82912007-03-16 13:38:11 -08002413
2414 retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
2415 if (retval)
2416 goto out;
2417
2418 /*
2419 * Finally, try again to invalidate clean pages which might have been
2420 * faulted in by get_user_pages() if the source of the write was an
2421 * mmap()ed region of the file we're writing. That's a pretty crazy
2422 * thing to do, so we don't support it 100%. If this invalidation
2423 * fails and we have -EIOCBQUEUED we ignore the failure.
2424 */
2425 if (rw == WRITE && mapping->nrpages) {
2426 int err = invalidate_inode_pages2_range(mapping,
2427 offset >> PAGE_CACHE_SHIFT, end);
2428 if (err && retval >= 0)
2429 retval = err;
2430 }
2431out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002432 return retval;
2433}
David Howellscf9a2ae2006-08-29 19:05:54 +01002434
2435/**
2436 * try_to_release_page() - release old fs-specific metadata on a page
2437 *
2438 * @page: the page which the kernel is trying to free
2439 * @gfp_mask: memory allocation flags (and I/O mode)
2440 *
2441 * The address_space is to try to release any data against the page
2442 * (presumably at page->private). If the release was successful, return `1'.
2443 * Otherwise return zero.
2444 *
2445 * The @gfp_mask argument specifies whether I/O may be performed to release
2446 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2447 *
2448 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2449 */
2450int try_to_release_page(struct page *page, gfp_t gfp_mask)
2451{
2452 struct address_space * const mapping = page->mapping;
2453
2454 BUG_ON(!PageLocked(page));
2455 if (PageWriteback(page))
2456 return 0;
2457
2458 if (mapping && mapping->a_ops->releasepage)
2459 return mapping->a_ops->releasepage(page, gfp_mask);
2460 return try_to_free_buffers(page);
2461}
2462
2463EXPORT_SYMBOL(try_to_release_page);