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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 *
78 * ->mmap_sem
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080079 * ->i_mutex (msync)
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 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -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
470struct page *page_cache_alloc(struct address_space *x)
471{
472 if (cpuset_do_page_mem_spread()) {
473 int n = cpuset_mem_spread_node();
474 return alloc_pages_node(n, mapping_gfp_mask(x), 0);
475 }
476 return alloc_pages(mapping_gfp_mask(x), 0);
477}
478EXPORT_SYMBOL(page_cache_alloc);
479
480struct page *page_cache_alloc_cold(struct address_space *x)
481{
482 if (cpuset_do_page_mem_spread()) {
483 int n = cpuset_mem_spread_node();
484 return alloc_pages_node(n, mapping_gfp_mask(x)|__GFP_COLD, 0);
485 }
486 return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD, 0);
487}
488EXPORT_SYMBOL(page_cache_alloc_cold);
489#endif
490
Nick Piggindb376482006-09-25 23:31:24 -0700491static int __sleep_on_page_lock(void *word)
492{
493 io_schedule();
494 return 0;
495}
496
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497/*
498 * In order to wait for pages to become available there must be
499 * waitqueues associated with pages. By using a hash table of
500 * waitqueues where the bucket discipline is to maintain all
501 * waiters on the same queue and wake all when any of the pages
502 * become available, and for the woken contexts to check to be
503 * sure the appropriate page became available, this saves space
504 * at a cost of "thundering herd" phenomena during rare hash
505 * collisions.
506 */
507static wait_queue_head_t *page_waitqueue(struct page *page)
508{
509 const struct zone *zone = page_zone(page);
510
511 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
512}
513
514static inline void wake_up_page(struct page *page, int bit)
515{
516 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
517}
518
519void fastcall wait_on_page_bit(struct page *page, int bit_nr)
520{
521 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
522
523 if (test_bit(bit_nr, &page->flags))
524 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
525 TASK_UNINTERRUPTIBLE);
526}
527EXPORT_SYMBOL(wait_on_page_bit);
528
529/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700530 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 * @page: the page
532 *
533 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
534 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
535 * mechananism between PageLocked pages and PageWriteback pages is shared.
536 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
537 *
538 * The first mb is necessary to safely close the critical section opened by the
539 * TestSetPageLocked(), the second mb is necessary to enforce ordering between
540 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
541 * parallel wait_on_page_locked()).
542 */
543void fastcall unlock_page(struct page *page)
544{
545 smp_mb__before_clear_bit();
546 if (!TestClearPageLocked(page))
547 BUG();
548 smp_mb__after_clear_bit();
549 wake_up_page(page, PG_locked);
550}
551EXPORT_SYMBOL(unlock_page);
552
Randy Dunlap485bb992006-06-23 02:03:49 -0700553/**
554 * end_page_writeback - end writeback against a page
555 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 */
557void end_page_writeback(struct page *page)
558{
559 if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
560 if (!test_clear_page_writeback(page))
561 BUG();
562 }
563 smp_mb__after_clear_bit();
564 wake_up_page(page, PG_writeback);
565}
566EXPORT_SYMBOL(end_page_writeback);
567
Randy Dunlap485bb992006-06-23 02:03:49 -0700568/**
569 * __lock_page - get a lock on the page, assuming we need to sleep to get it
570 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700572 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
574 * chances are that on the second loop, the block layer's plug list is empty,
575 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
576 */
577void fastcall __lock_page(struct page *page)
578{
579 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
580
581 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
582 TASK_UNINTERRUPTIBLE);
583}
584EXPORT_SYMBOL(__lock_page);
585
Nick Piggindb376482006-09-25 23:31:24 -0700586/*
587 * Variant of lock_page that does not require the caller to hold a reference
588 * on the page's mapping.
589 */
590void fastcall __lock_page_nosync(struct page *page)
591{
592 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
593 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
594 TASK_UNINTERRUPTIBLE);
595}
596
Randy Dunlap485bb992006-06-23 02:03:49 -0700597/**
598 * find_get_page - find and get a page reference
599 * @mapping: the address_space to search
600 * @offset: the page index
601 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700602 * Is there a pagecache struct page at the given (mapping, offset) tuple?
603 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700604 */
605struct page * find_get_page(struct address_space *mapping, unsigned long offset)
606{
607 struct page *page;
608
609 read_lock_irq(&mapping->tree_lock);
610 page = radix_tree_lookup(&mapping->page_tree, offset);
611 if (page)
612 page_cache_get(page);
613 read_unlock_irq(&mapping->tree_lock);
614 return page;
615}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616EXPORT_SYMBOL(find_get_page);
617
Randy Dunlap485bb992006-06-23 02:03:49 -0700618/**
619 * find_trylock_page - find and lock a page
620 * @mapping: the address_space to search
621 * @offset: the page index
622 *
623 * Same as find_get_page(), but trylock it instead of incrementing the count.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 */
625struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
626{
627 struct page *page;
628
629 read_lock_irq(&mapping->tree_lock);
630 page = radix_tree_lookup(&mapping->page_tree, offset);
631 if (page && TestSetPageLocked(page))
632 page = NULL;
633 read_unlock_irq(&mapping->tree_lock);
634 return page;
635}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636EXPORT_SYMBOL(find_trylock_page);
637
638/**
639 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700640 * @mapping: the address_space to search
641 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 *
643 * Locates the desired pagecache page, locks it, increments its reference
644 * count and returns its address.
645 *
646 * Returns zero if the page was not present. find_lock_page() may sleep.
647 */
648struct page *find_lock_page(struct address_space *mapping,
649 unsigned long offset)
650{
651 struct page *page;
652
653 read_lock_irq(&mapping->tree_lock);
654repeat:
655 page = radix_tree_lookup(&mapping->page_tree, offset);
656 if (page) {
657 page_cache_get(page);
658 if (TestSetPageLocked(page)) {
659 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800660 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 read_lock_irq(&mapping->tree_lock);
662
663 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800664 if (unlikely(page->mapping != mapping ||
665 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 unlock_page(page);
667 page_cache_release(page);
668 goto repeat;
669 }
670 }
671 }
672 read_unlock_irq(&mapping->tree_lock);
673 return page;
674}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675EXPORT_SYMBOL(find_lock_page);
676
677/**
678 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700679 * @mapping: the page's address_space
680 * @index: the page's index into the mapping
681 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 *
683 * Locates a page in the pagecache. If the page is not present, a new page
684 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
685 * LRU list. The returned page is locked and has its reference count
686 * incremented.
687 *
688 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
689 * allocation!
690 *
691 * find_or_create_page() returns the desired page's address, or zero on
692 * memory exhaustion.
693 */
694struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400695 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696{
697 struct page *page, *cached_page = NULL;
698 int err;
699repeat:
700 page = find_lock_page(mapping, index);
701 if (!page) {
702 if (!cached_page) {
703 cached_page = alloc_page(gfp_mask);
704 if (!cached_page)
705 return NULL;
706 }
707 err = add_to_page_cache_lru(cached_page, mapping,
708 index, gfp_mask);
709 if (!err) {
710 page = cached_page;
711 cached_page = NULL;
712 } else if (err == -EEXIST)
713 goto repeat;
714 }
715 if (cached_page)
716 page_cache_release(cached_page);
717 return page;
718}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719EXPORT_SYMBOL(find_or_create_page);
720
721/**
722 * find_get_pages - gang pagecache lookup
723 * @mapping: The address_space to search
724 * @start: The starting page index
725 * @nr_pages: The maximum number of pages
726 * @pages: Where the resulting pages are placed
727 *
728 * find_get_pages() will search for and return a group of up to
729 * @nr_pages pages in the mapping. The pages are placed at @pages.
730 * find_get_pages() takes a reference against the returned pages.
731 *
732 * The search returns a group of mapping-contiguous pages with ascending
733 * indexes. There may be holes in the indices due to not-present pages.
734 *
735 * find_get_pages() returns the number of pages which were found.
736 */
737unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
738 unsigned int nr_pages, struct page **pages)
739{
740 unsigned int i;
741 unsigned int ret;
742
743 read_lock_irq(&mapping->tree_lock);
744 ret = radix_tree_gang_lookup(&mapping->page_tree,
745 (void **)pages, start, nr_pages);
746 for (i = 0; i < ret; i++)
747 page_cache_get(pages[i]);
748 read_unlock_irq(&mapping->tree_lock);
749 return ret;
750}
751
Jens Axboeebf43502006-04-27 08:46:01 +0200752/**
753 * find_get_pages_contig - gang contiguous pagecache lookup
754 * @mapping: The address_space to search
755 * @index: The starting page index
756 * @nr_pages: The maximum number of pages
757 * @pages: Where the resulting pages are placed
758 *
759 * find_get_pages_contig() works exactly like find_get_pages(), except
760 * that the returned number of pages are guaranteed to be contiguous.
761 *
762 * find_get_pages_contig() returns the number of pages which were found.
763 */
764unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
765 unsigned int nr_pages, struct page **pages)
766{
767 unsigned int i;
768 unsigned int ret;
769
770 read_lock_irq(&mapping->tree_lock);
771 ret = radix_tree_gang_lookup(&mapping->page_tree,
772 (void **)pages, index, nr_pages);
773 for (i = 0; i < ret; i++) {
774 if (pages[i]->mapping == NULL || pages[i]->index != index)
775 break;
776
777 page_cache_get(pages[i]);
778 index++;
779 }
780 read_unlock_irq(&mapping->tree_lock);
781 return i;
782}
783
Randy Dunlap485bb992006-06-23 02:03:49 -0700784/**
785 * find_get_pages_tag - find and return pages that match @tag
786 * @mapping: the address_space to search
787 * @index: the starting page index
788 * @tag: the tag index
789 * @nr_pages: the maximum number of pages
790 * @pages: where the resulting pages are placed
791 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700793 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 */
795unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
796 int tag, unsigned int nr_pages, struct page **pages)
797{
798 unsigned int i;
799 unsigned int ret;
800
801 read_lock_irq(&mapping->tree_lock);
802 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
803 (void **)pages, *index, nr_pages, tag);
804 for (i = 0; i < ret; i++)
805 page_cache_get(pages[i]);
806 if (ret)
807 *index = pages[ret - 1]->index + 1;
808 read_unlock_irq(&mapping->tree_lock);
809 return ret;
810}
811
Randy Dunlap485bb992006-06-23 02:03:49 -0700812/**
813 * grab_cache_page_nowait - returns locked page at given index in given cache
814 * @mapping: target address_space
815 * @index: the page index
816 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700817 * Same as grab_cache_page, but do not wait if the page is unavailable.
818 * This is intended for speculative data generators, where the data can
819 * be regenerated if the page couldn't be grabbed. This routine should
820 * be safe to call while holding the lock for another page.
821 *
822 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
823 * and deadlock against the caller's locked page.
824 */
825struct page *
826grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
827{
828 struct page *page = find_get_page(mapping, index);
Al Viro6daa0e22005-10-21 03:18:50 -0400829 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830
831 if (page) {
832 if (!TestSetPageLocked(page))
833 return page;
834 page_cache_release(page);
835 return NULL;
836 }
837 gfp_mask = mapping_gfp_mask(mapping) & ~__GFP_FS;
838 page = alloc_pages(gfp_mask, 0);
839 if (page && add_to_page_cache_lru(page, mapping, index, gfp_mask)) {
840 page_cache_release(page);
841 page = NULL;
842 }
843 return page;
844}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845EXPORT_SYMBOL(grab_cache_page_nowait);
846
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700847/*
848 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
849 * a _large_ part of the i/o request. Imagine the worst scenario:
850 *
851 * ---R__________________________________________B__________
852 * ^ reading here ^ bad block(assume 4k)
853 *
854 * read(R) => miss => readahead(R...B) => media error => frustrating retries
855 * => failing the whole request => read(R) => read(R+1) =>
856 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
857 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
858 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
859 *
860 * It is going insane. Fix it by quickly scaling down the readahead size.
861 */
862static void shrink_readahead_size_eio(struct file *filp,
863 struct file_ra_state *ra)
864{
865 if (!ra->ra_pages)
866 return;
867
868 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700869}
870
Randy Dunlap485bb992006-06-23 02:03:49 -0700871/**
872 * do_generic_mapping_read - generic file read routine
873 * @mapping: address_space to be read
874 * @_ra: file's readahead state
875 * @filp: the file to read
876 * @ppos: current file position
877 * @desc: read_descriptor
878 * @actor: read method
879 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700881 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 *
883 * This is really ugly. But the goto's actually try to clarify some
884 * of the logic when it comes to error handling etc.
885 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700886 * Note the struct file* is only passed for the use of readpage.
887 * It may be NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888 */
889void do_generic_mapping_read(struct address_space *mapping,
890 struct file_ra_state *_ra,
891 struct file *filp,
892 loff_t *ppos,
893 read_descriptor_t *desc,
894 read_actor_t actor)
895{
896 struct inode *inode = mapping->host;
897 unsigned long index;
898 unsigned long end_index;
899 unsigned long offset;
900 unsigned long last_index;
901 unsigned long next_index;
902 unsigned long prev_index;
903 loff_t isize;
904 struct page *cached_page;
905 int error;
906 struct file_ra_state ra = *_ra;
907
908 cached_page = NULL;
909 index = *ppos >> PAGE_CACHE_SHIFT;
910 next_index = index;
911 prev_index = ra.prev_page;
912 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
913 offset = *ppos & ~PAGE_CACHE_MASK;
914
915 isize = i_size_read(inode);
916 if (!isize)
917 goto out;
918
919 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
920 for (;;) {
921 struct page *page;
922 unsigned long nr, ret;
923
924 /* nr is the maximum number of bytes to copy from this page */
925 nr = PAGE_CACHE_SIZE;
926 if (index >= end_index) {
927 if (index > end_index)
928 goto out;
929 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
930 if (nr <= offset) {
931 goto out;
932 }
933 }
934 nr = nr - offset;
935
936 cond_resched();
937 if (index == next_index)
938 next_index = page_cache_readahead(mapping, &ra, filp,
939 index, last_index - index);
940
941find_page:
942 page = find_get_page(mapping, index);
943 if (unlikely(page == NULL)) {
944 handle_ra_miss(mapping, &ra, index);
945 goto no_cached_page;
946 }
947 if (!PageUptodate(page))
948 goto page_not_up_to_date;
949page_ok:
950
951 /* If users can be writing to this page using arbitrary
952 * virtual addresses, take care about potential aliasing
953 * before reading the page on the kernel side.
954 */
955 if (mapping_writably_mapped(mapping))
956 flush_dcache_page(page);
957
958 /*
959 * When (part of) the same page is read multiple times
960 * in succession, only mark it as accessed the first time.
961 */
962 if (prev_index != index)
963 mark_page_accessed(page);
964 prev_index = index;
965
966 /*
967 * Ok, we have the page, and it's up-to-date, so
968 * now we can copy it to user space...
969 *
970 * The actor routine returns how many bytes were actually used..
971 * NOTE! This may not be the same as how much of a user buffer
972 * we filled up (we may be padding etc), so we can only update
973 * "pos" here (the actor routine has to update the user buffer
974 * pointers and the remaining count).
975 */
976 ret = actor(desc, page, offset, nr);
977 offset += ret;
978 index += offset >> PAGE_CACHE_SHIFT;
979 offset &= ~PAGE_CACHE_MASK;
980
981 page_cache_release(page);
982 if (ret == nr && desc->count)
983 continue;
984 goto out;
985
986page_not_up_to_date:
987 /* Get exclusive access to the page ... */
988 lock_page(page);
989
Nick Pigginda6052f2006-09-25 23:31:35 -0700990 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700991 if (!page->mapping) {
992 unlock_page(page);
993 page_cache_release(page);
994 continue;
995 }
996
997 /* Did somebody else fill it already? */
998 if (PageUptodate(page)) {
999 unlock_page(page);
1000 goto page_ok;
1001 }
1002
1003readpage:
1004 /* Start the actual read. The read will unlock the page. */
1005 error = mapping->a_ops->readpage(filp, page);
1006
Zach Brown994fc28c2005-12-15 14:28:17 -08001007 if (unlikely(error)) {
1008 if (error == AOP_TRUNCATED_PAGE) {
1009 page_cache_release(page);
1010 goto find_page;
1011 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001013 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014
1015 if (!PageUptodate(page)) {
1016 lock_page(page);
1017 if (!PageUptodate(page)) {
1018 if (page->mapping == NULL) {
1019 /*
1020 * invalidate_inode_pages got it
1021 */
1022 unlock_page(page);
1023 page_cache_release(page);
1024 goto find_page;
1025 }
1026 unlock_page(page);
1027 error = -EIO;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001028 shrink_readahead_size_eio(filp, &ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 goto readpage_error;
1030 }
1031 unlock_page(page);
1032 }
1033
1034 /*
1035 * i_size must be checked after we have done ->readpage.
1036 *
1037 * Checking i_size after the readpage allows us to calculate
1038 * the correct value for "nr", which means the zero-filled
1039 * part of the page is not copied back to userspace (unless
1040 * another truncate extends the file - this is desired though).
1041 */
1042 isize = i_size_read(inode);
1043 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1044 if (unlikely(!isize || index > end_index)) {
1045 page_cache_release(page);
1046 goto out;
1047 }
1048
1049 /* nr is the maximum number of bytes to copy from this page */
1050 nr = PAGE_CACHE_SIZE;
1051 if (index == end_index) {
1052 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1053 if (nr <= offset) {
1054 page_cache_release(page);
1055 goto out;
1056 }
1057 }
1058 nr = nr - offset;
1059 goto page_ok;
1060
1061readpage_error:
1062 /* UHHUH! A synchronous read error occurred. Report it */
1063 desc->error = error;
1064 page_cache_release(page);
1065 goto out;
1066
1067no_cached_page:
1068 /*
1069 * Ok, it wasn't cached, so we need to create a new
1070 * page..
1071 */
1072 if (!cached_page) {
1073 cached_page = page_cache_alloc_cold(mapping);
1074 if (!cached_page) {
1075 desc->error = -ENOMEM;
1076 goto out;
1077 }
1078 }
1079 error = add_to_page_cache_lru(cached_page, mapping,
1080 index, GFP_KERNEL);
1081 if (error) {
1082 if (error == -EEXIST)
1083 goto find_page;
1084 desc->error = error;
1085 goto out;
1086 }
1087 page = cached_page;
1088 cached_page = NULL;
1089 goto readpage;
1090 }
1091
1092out:
1093 *_ra = ra;
1094
1095 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1096 if (cached_page)
1097 page_cache_release(cached_page);
1098 if (filp)
1099 file_accessed(filp);
1100}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101EXPORT_SYMBOL(do_generic_mapping_read);
1102
1103int file_read_actor(read_descriptor_t *desc, struct page *page,
1104 unsigned long offset, unsigned long size)
1105{
1106 char *kaddr;
1107 unsigned long left, count = desc->count;
1108
1109 if (size > count)
1110 size = count;
1111
1112 /*
1113 * Faults on the destination of a read are common, so do it before
1114 * taking the kmap.
1115 */
1116 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1117 kaddr = kmap_atomic(page, KM_USER0);
1118 left = __copy_to_user_inatomic(desc->arg.buf,
1119 kaddr + offset, size);
1120 kunmap_atomic(kaddr, KM_USER0);
1121 if (left == 0)
1122 goto success;
1123 }
1124
1125 /* Do it the slow way */
1126 kaddr = kmap(page);
1127 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1128 kunmap(page);
1129
1130 if (left) {
1131 size -= left;
1132 desc->error = -EFAULT;
1133 }
1134success:
1135 desc->count = count - size;
1136 desc->written += size;
1137 desc->arg.buf += size;
1138 return size;
1139}
1140
Randy Dunlap485bb992006-06-23 02:03:49 -07001141/**
1142 * __generic_file_aio_read - generic filesystem read routine
1143 * @iocb: kernel I/O control block
1144 * @iov: io vector request
1145 * @nr_segs: number of segments in the iovec
1146 * @ppos: current file position
1147 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148 * This is the "read()" routine for all filesystems
1149 * that can use the page cache directly.
1150 */
1151ssize_t
1152__generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1153 unsigned long nr_segs, loff_t *ppos)
1154{
1155 struct file *filp = iocb->ki_filp;
1156 ssize_t retval;
1157 unsigned long seg;
1158 size_t count;
1159
1160 count = 0;
1161 for (seg = 0; seg < nr_segs; seg++) {
1162 const struct iovec *iv = &iov[seg];
1163
1164 /*
1165 * If any segment has a negative length, or the cumulative
1166 * length ever wraps negative then return -EINVAL.
1167 */
1168 count += iv->iov_len;
1169 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1170 return -EINVAL;
1171 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1172 continue;
1173 if (seg == 0)
1174 return -EFAULT;
1175 nr_segs = seg;
1176 count -= iv->iov_len; /* This segment is no good */
1177 break;
1178 }
1179
1180 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1181 if (filp->f_flags & O_DIRECT) {
1182 loff_t pos = *ppos, size;
1183 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);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001195 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196 retval = -EIOCBQUEUED;
1197 if (retval > 0)
1198 *ppos = pos + retval;
1199 }
1200 file_accessed(filp);
1201 goto out;
1202 }
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
1228ssize_t
1229generic_file_aio_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos)
1230{
1231 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1232
1233 BUG_ON(iocb->ki_pos != pos);
1234 return __generic_file_aio_read(iocb, &local_iov, 1, &iocb->ki_pos);
1235}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001236EXPORT_SYMBOL(generic_file_aio_read);
1237
1238ssize_t
1239generic_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1240{
1241 struct iovec local_iov = { .iov_base = buf, .iov_len = count };
1242 struct kiocb kiocb;
1243 ssize_t ret;
1244
1245 init_sync_kiocb(&kiocb, filp);
1246 ret = __generic_file_aio_read(&kiocb, &local_iov, 1, ppos);
1247 if (-EIOCBQUEUED == ret)
1248 ret = wait_on_sync_kiocb(&kiocb);
1249 return ret;
1250}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251EXPORT_SYMBOL(generic_file_read);
1252
1253int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1254{
1255 ssize_t written;
1256 unsigned long count = desc->count;
1257 struct file *file = desc->arg.data;
1258
1259 if (size > count)
1260 size = count;
1261
1262 written = file->f_op->sendpage(file, page, offset,
1263 size, &file->f_pos, size<count);
1264 if (written < 0) {
1265 desc->error = written;
1266 written = 0;
1267 }
1268 desc->count = count - written;
1269 desc->written += written;
1270 return written;
1271}
1272
1273ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1274 size_t count, read_actor_t actor, void *target)
1275{
1276 read_descriptor_t desc;
1277
1278 if (!count)
1279 return 0;
1280
1281 desc.written = 0;
1282 desc.count = count;
1283 desc.arg.data = target;
1284 desc.error = 0;
1285
1286 do_generic_file_read(in_file, ppos, &desc, actor);
1287 if (desc.written)
1288 return desc.written;
1289 return desc.error;
1290}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291EXPORT_SYMBOL(generic_file_sendfile);
1292
1293static ssize_t
1294do_readahead(struct address_space *mapping, struct file *filp,
1295 unsigned long index, unsigned long nr)
1296{
1297 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1298 return -EINVAL;
1299
1300 force_page_cache_readahead(mapping, filp, index,
1301 max_sane_readahead(nr));
1302 return 0;
1303}
1304
1305asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1306{
1307 ssize_t ret;
1308 struct file *file;
1309
1310 ret = -EBADF;
1311 file = fget(fd);
1312 if (file) {
1313 if (file->f_mode & FMODE_READ) {
1314 struct address_space *mapping = file->f_mapping;
1315 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1316 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1317 unsigned long len = end - start + 1;
1318 ret = do_readahead(mapping, file, start, len);
1319 }
1320 fput(file);
1321 }
1322 return ret;
1323}
1324
1325#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001326static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1327/**
1328 * page_cache_read - adds requested page to the page cache if not already there
1329 * @file: file to read
1330 * @offset: page index
1331 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 * This adds the requested page to the page cache if it isn't already there,
1333 * and schedules an I/O to read in its contents from disk.
1334 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335static int fastcall page_cache_read(struct file * file, unsigned long offset)
1336{
1337 struct address_space *mapping = file->f_mapping;
1338 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001339 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340
Zach Brown994fc28c2005-12-15 14:28:17 -08001341 do {
1342 page = page_cache_alloc_cold(mapping);
1343 if (!page)
1344 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345
Zach Brown994fc28c2005-12-15 14:28:17 -08001346 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1347 if (ret == 0)
1348 ret = mapping->a_ops->readpage(file, page);
1349 else if (ret == -EEXIST)
1350 ret = 0; /* losing race to add is OK */
1351
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
Zach Brown994fc28c2005-12-15 14:28:17 -08001354 } while (ret == AOP_TRUNCATED_PAGE);
1355
1356 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001357}
1358
1359#define MMAP_LOTSAMISS (100)
1360
Randy Dunlap485bb992006-06-23 02:03:49 -07001361/**
1362 * filemap_nopage - read in file data for page fault handling
1363 * @area: the applicable vm_area
1364 * @address: target address to read in
1365 * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1366 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001367 * filemap_nopage() is invoked via the vma operations vector for a
1368 * mapped memory region to read in file data during a page fault.
1369 *
1370 * The goto's are kind of ugly, but this streamlines the normal case of having
1371 * it in the page cache, and handles the special cases reasonably without
1372 * having a lot of duplicated code.
1373 */
1374struct page *filemap_nopage(struct vm_area_struct *area,
1375 unsigned long address, int *type)
1376{
1377 int error;
1378 struct file *file = area->vm_file;
1379 struct address_space *mapping = file->f_mapping;
1380 struct file_ra_state *ra = &file->f_ra;
1381 struct inode *inode = mapping->host;
1382 struct page *page;
1383 unsigned long size, pgoff;
1384 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1385
1386 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1387
1388retry_all:
1389 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1390 if (pgoff >= size)
1391 goto outside_data_content;
1392
1393 /* If we don't want any read-ahead, don't bother */
1394 if (VM_RandomReadHint(area))
1395 goto no_cached_page;
1396
1397 /*
1398 * The readahead code wants to be told about each and every page
1399 * so it can build and shrink its windows appropriately
1400 *
1401 * For sequential accesses, we use the generic readahead logic.
1402 */
1403 if (VM_SequentialReadHint(area))
1404 page_cache_readahead(mapping, ra, file, pgoff, 1);
1405
1406 /*
1407 * Do we have something in the page cache already?
1408 */
1409retry_find:
1410 page = find_get_page(mapping, pgoff);
1411 if (!page) {
1412 unsigned long ra_pages;
1413
1414 if (VM_SequentialReadHint(area)) {
1415 handle_ra_miss(mapping, ra, pgoff);
1416 goto no_cached_page;
1417 }
1418 ra->mmap_miss++;
1419
1420 /*
1421 * Do we miss much more than hit in this file? If so,
1422 * stop bothering with read-ahead. It will only hurt.
1423 */
1424 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1425 goto no_cached_page;
1426
1427 /*
1428 * To keep the pgmajfault counter straight, we need to
1429 * check did_readaround, as this is an inner loop.
1430 */
1431 if (!did_readaround) {
1432 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001433 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 }
1435 did_readaround = 1;
1436 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1437 if (ra_pages) {
1438 pgoff_t start = 0;
1439
1440 if (pgoff > ra_pages / 2)
1441 start = pgoff - ra_pages / 2;
1442 do_page_cache_readahead(mapping, file, start, ra_pages);
1443 }
1444 page = find_get_page(mapping, pgoff);
1445 if (!page)
1446 goto no_cached_page;
1447 }
1448
1449 if (!did_readaround)
1450 ra->mmap_hit++;
1451
1452 /*
1453 * Ok, found a page in the page cache, now we need to check
1454 * that it's up-to-date.
1455 */
1456 if (!PageUptodate(page))
1457 goto page_not_uptodate;
1458
1459success:
1460 /*
1461 * Found the page and have a reference on it.
1462 */
1463 mark_page_accessed(page);
1464 if (type)
1465 *type = majmin;
1466 return page;
1467
1468outside_data_content:
1469 /*
1470 * An external ptracer can access pages that normally aren't
1471 * accessible..
1472 */
1473 if (area->vm_mm == current->mm)
Adam Litke79f5acf2006-09-29 01:58:43 -07001474 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 /* Fall through to the non-read-ahead case */
1476no_cached_page:
1477 /*
1478 * We're only likely to ever get here if MADV_RANDOM is in
1479 * effect.
1480 */
1481 error = page_cache_read(file, pgoff);
1482 grab_swap_token();
1483
1484 /*
1485 * The page we want has now been added to the page cache.
1486 * In the unlikely event that someone removed it in the
1487 * meantime, we'll just come back here and read it again.
1488 */
1489 if (error >= 0)
1490 goto retry_find;
1491
1492 /*
1493 * An error return from page_cache_read can result if the
1494 * system is low on memory, or a problem occurs while trying
1495 * to schedule I/O.
1496 */
1497 if (error == -ENOMEM)
1498 return NOPAGE_OOM;
Adam Litke79f5acf2006-09-29 01:58:43 -07001499 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500
1501page_not_uptodate:
1502 if (!did_readaround) {
1503 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001504 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 }
1506 lock_page(page);
1507
1508 /* Did it get unhashed while we waited for it? */
1509 if (!page->mapping) {
1510 unlock_page(page);
1511 page_cache_release(page);
1512 goto retry_all;
1513 }
1514
1515 /* Did somebody else get it up-to-date? */
1516 if (PageUptodate(page)) {
1517 unlock_page(page);
1518 goto success;
1519 }
1520
Zach Brown994fc28c2005-12-15 14:28:17 -08001521 error = mapping->a_ops->readpage(file, page);
1522 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523 wait_on_page_locked(page);
1524 if (PageUptodate(page))
1525 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001526 } else if (error == AOP_TRUNCATED_PAGE) {
1527 page_cache_release(page);
1528 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 }
1530
1531 /*
1532 * Umm, take care of errors if the page isn't up-to-date.
1533 * Try to re-read it _once_. We do this synchronously,
1534 * because there really aren't any performance issues here
1535 * and we need to check for errors.
1536 */
1537 lock_page(page);
1538
1539 /* Somebody truncated the page on us? */
1540 if (!page->mapping) {
1541 unlock_page(page);
1542 page_cache_release(page);
1543 goto retry_all;
1544 }
1545
1546 /* Somebody else successfully read it in? */
1547 if (PageUptodate(page)) {
1548 unlock_page(page);
1549 goto success;
1550 }
1551 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001552 error = mapping->a_ops->readpage(file, page);
1553 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 wait_on_page_locked(page);
1555 if (PageUptodate(page))
1556 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001557 } else if (error == AOP_TRUNCATED_PAGE) {
1558 page_cache_release(page);
1559 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 }
1561
1562 /*
1563 * Things didn't work out. Return zero to tell the
1564 * mm layer so, possibly freeing the page cache page first.
1565 */
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001566 shrink_readahead_size_eio(file, ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567 page_cache_release(page);
Adam Litke79f5acf2006-09-29 01:58:43 -07001568 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570EXPORT_SYMBOL(filemap_nopage);
1571
1572static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1573 int nonblock)
1574{
1575 struct address_space *mapping = file->f_mapping;
1576 struct page *page;
1577 int error;
1578
1579 /*
1580 * Do we have something in the page cache already?
1581 */
1582retry_find:
1583 page = find_get_page(mapping, pgoff);
1584 if (!page) {
1585 if (nonblock)
1586 return NULL;
1587 goto no_cached_page;
1588 }
1589
1590 /*
1591 * Ok, found a page in the page cache, now we need to check
1592 * that it's up-to-date.
1593 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001594 if (!PageUptodate(page)) {
1595 if (nonblock) {
1596 page_cache_release(page);
1597 return NULL;
1598 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001600 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601
1602success:
1603 /*
1604 * Found the page and have a reference on it.
1605 */
1606 mark_page_accessed(page);
1607 return page;
1608
1609no_cached_page:
1610 error = page_cache_read(file, pgoff);
1611
1612 /*
1613 * The page we want has now been added to the page cache.
1614 * In the unlikely event that someone removed it in the
1615 * meantime, we'll just come back here and read it again.
1616 */
1617 if (error >= 0)
1618 goto retry_find;
1619
1620 /*
1621 * An error return from page_cache_read can result if the
1622 * system is low on memory, or a problem occurs while trying
1623 * to schedule I/O.
1624 */
1625 return NULL;
1626
1627page_not_uptodate:
1628 lock_page(page);
1629
Nick Pigginda6052f2006-09-25 23:31:35 -07001630 /* Did it get truncated while we waited for it? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 if (!page->mapping) {
1632 unlock_page(page);
1633 goto err;
1634 }
1635
1636 /* Did somebody else get it up-to-date? */
1637 if (PageUptodate(page)) {
1638 unlock_page(page);
1639 goto success;
1640 }
1641
Zach Brown994fc28c2005-12-15 14:28:17 -08001642 error = mapping->a_ops->readpage(file, page);
1643 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 wait_on_page_locked(page);
1645 if (PageUptodate(page))
1646 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001647 } else if (error == AOP_TRUNCATED_PAGE) {
1648 page_cache_release(page);
1649 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 }
1651
1652 /*
1653 * Umm, take care of errors if the page isn't up-to-date.
1654 * Try to re-read it _once_. We do this synchronously,
1655 * because there really aren't any performance issues here
1656 * and we need to check for errors.
1657 */
1658 lock_page(page);
1659
1660 /* Somebody truncated the page on us? */
1661 if (!page->mapping) {
1662 unlock_page(page);
1663 goto err;
1664 }
1665 /* Somebody else successfully read it in? */
1666 if (PageUptodate(page)) {
1667 unlock_page(page);
1668 goto success;
1669 }
1670
1671 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001672 error = mapping->a_ops->readpage(file, page);
1673 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001674 wait_on_page_locked(page);
1675 if (PageUptodate(page))
1676 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001677 } else if (error == AOP_TRUNCATED_PAGE) {
1678 page_cache_release(page);
1679 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 }
1681
1682 /*
1683 * Things didn't work out. Return zero to tell the
1684 * mm layer so, possibly freeing the page cache page first.
1685 */
1686err:
1687 page_cache_release(page);
1688
1689 return NULL;
1690}
1691
1692int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1693 unsigned long len, pgprot_t prot, unsigned long pgoff,
1694 int nonblock)
1695{
1696 struct file *file = vma->vm_file;
1697 struct address_space *mapping = file->f_mapping;
1698 struct inode *inode = mapping->host;
1699 unsigned long size;
1700 struct mm_struct *mm = vma->vm_mm;
1701 struct page *page;
1702 int err;
1703
1704 if (!nonblock)
1705 force_page_cache_readahead(mapping, vma->vm_file,
1706 pgoff, len >> PAGE_CACHE_SHIFT);
1707
1708repeat:
1709 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1710 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1711 return -EINVAL;
1712
1713 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001714
1715 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1716 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 if (!page && !nonblock)
1718 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001719
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 if (page) {
1721 err = install_page(mm, vma, addr, page, prot);
1722 if (err) {
1723 page_cache_release(page);
1724 return err;
1725 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001726 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001727 /* No page was found just because we can't read it in now (being
1728 * here implies nonblock != 0), but the page may exist, so set
1729 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 err = install_file_pte(mm, vma, addr, pgoff, prot);
1731 if (err)
1732 return err;
1733 }
1734
1735 len -= PAGE_SIZE;
1736 addr += PAGE_SIZE;
1737 pgoff++;
1738 if (len)
1739 goto repeat;
1740
1741 return 0;
1742}
Nikita Danilovb1459462005-10-29 18:17:02 -07001743EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744
1745struct vm_operations_struct generic_file_vm_ops = {
1746 .nopage = filemap_nopage,
1747 .populate = filemap_populate,
1748};
1749
1750/* This is used for a general mmap of a disk file */
1751
1752int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1753{
1754 struct address_space *mapping = file->f_mapping;
1755
1756 if (!mapping->a_ops->readpage)
1757 return -ENOEXEC;
1758 file_accessed(file);
1759 vma->vm_ops = &generic_file_vm_ops;
1760 return 0;
1761}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762
1763/*
1764 * This is for filesystems which do not implement ->writepage.
1765 */
1766int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1767{
1768 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1769 return -EINVAL;
1770 return generic_file_mmap(file, vma);
1771}
1772#else
1773int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1774{
1775 return -ENOSYS;
1776}
1777int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1778{
1779 return -ENOSYS;
1780}
1781#endif /* CONFIG_MMU */
1782
1783EXPORT_SYMBOL(generic_file_mmap);
1784EXPORT_SYMBOL(generic_file_readonly_mmap);
1785
1786static inline struct page *__read_cache_page(struct address_space *mapping,
1787 unsigned long index,
1788 int (*filler)(void *,struct page*),
1789 void *data)
1790{
1791 struct page *page, *cached_page = NULL;
1792 int err;
1793repeat:
1794 page = find_get_page(mapping, index);
1795 if (!page) {
1796 if (!cached_page) {
1797 cached_page = page_cache_alloc_cold(mapping);
1798 if (!cached_page)
1799 return ERR_PTR(-ENOMEM);
1800 }
1801 err = add_to_page_cache_lru(cached_page, mapping,
1802 index, GFP_KERNEL);
1803 if (err == -EEXIST)
1804 goto repeat;
1805 if (err < 0) {
1806 /* Presumably ENOMEM for radix tree node */
1807 page_cache_release(cached_page);
1808 return ERR_PTR(err);
1809 }
1810 page = cached_page;
1811 cached_page = NULL;
1812 err = filler(data, page);
1813 if (err < 0) {
1814 page_cache_release(page);
1815 page = ERR_PTR(err);
1816 }
1817 }
1818 if (cached_page)
1819 page_cache_release(cached_page);
1820 return page;
1821}
1822
Randy Dunlap485bb992006-06-23 02:03:49 -07001823/**
1824 * read_cache_page - read into page cache, fill it if needed
1825 * @mapping: the page's address_space
1826 * @index: the page index
1827 * @filler: function to perform the read
1828 * @data: destination for read data
1829 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 * Read into the page cache. If a page already exists,
1831 * and PageUptodate() is not set, try to fill the page.
1832 */
1833struct page *read_cache_page(struct address_space *mapping,
1834 unsigned long index,
1835 int (*filler)(void *,struct page*),
1836 void *data)
1837{
1838 struct page *page;
1839 int err;
1840
1841retry:
1842 page = __read_cache_page(mapping, index, filler, data);
1843 if (IS_ERR(page))
1844 goto out;
1845 mark_page_accessed(page);
1846 if (PageUptodate(page))
1847 goto out;
1848
1849 lock_page(page);
1850 if (!page->mapping) {
1851 unlock_page(page);
1852 page_cache_release(page);
1853 goto retry;
1854 }
1855 if (PageUptodate(page)) {
1856 unlock_page(page);
1857 goto out;
1858 }
1859 err = filler(data, page);
1860 if (err < 0) {
1861 page_cache_release(page);
1862 page = ERR_PTR(err);
1863 }
1864 out:
1865 return page;
1866}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867EXPORT_SYMBOL(read_cache_page);
1868
1869/*
1870 * If the page was newly created, increment its refcount and add it to the
1871 * caller's lru-buffering pagevec. This function is specifically for
1872 * generic_file_write().
1873 */
1874static inline struct page *
1875__grab_cache_page(struct address_space *mapping, unsigned long index,
1876 struct page **cached_page, struct pagevec *lru_pvec)
1877{
1878 int err;
1879 struct page *page;
1880repeat:
1881 page = find_lock_page(mapping, index);
1882 if (!page) {
1883 if (!*cached_page) {
1884 *cached_page = page_cache_alloc(mapping);
1885 if (!*cached_page)
1886 return NULL;
1887 }
1888 err = add_to_page_cache(*cached_page, mapping,
1889 index, GFP_KERNEL);
1890 if (err == -EEXIST)
1891 goto repeat;
1892 if (err == 0) {
1893 page = *cached_page;
1894 page_cache_get(page);
1895 if (!pagevec_add(lru_pvec, page))
1896 __pagevec_lru_add(lru_pvec);
1897 *cached_page = NULL;
1898 }
1899 }
1900 return page;
1901}
1902
1903/*
1904 * The logic we want is
1905 *
1906 * if suid or (sgid and xgrp)
1907 * remove privs
1908 */
1909int remove_suid(struct dentry *dentry)
1910{
1911 mode_t mode = dentry->d_inode->i_mode;
1912 int kill = 0;
1913 int result = 0;
1914
1915 /* suid always must be killed */
1916 if (unlikely(mode & S_ISUID))
1917 kill = ATTR_KILL_SUID;
1918
1919 /*
1920 * sgid without any exec bits is just a mandatory locking mark; leave
1921 * it alone. If some exec bits are set, it's a real sgid; kill it.
1922 */
1923 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1924 kill |= ATTR_KILL_SGID;
1925
1926 if (unlikely(kill && !capable(CAP_FSETID))) {
1927 struct iattr newattrs;
1928
1929 newattrs.ia_valid = ATTR_FORCE | kill;
1930 result = notify_change(dentry, &newattrs);
1931 }
1932 return result;
1933}
1934EXPORT_SYMBOL(remove_suid);
1935
Carsten Otteceffc072005-06-23 22:05:25 -07001936size_t
NeilBrown01408c42006-06-25 05:47:58 -07001937__filemap_copy_from_user_iovec_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 const struct iovec *iov, size_t base, size_t bytes)
1939{
1940 size_t copied = 0, left = 0;
1941
1942 while (bytes) {
1943 char __user *buf = iov->iov_base + base;
1944 int copy = min(bytes, iov->iov_len - base);
1945
1946 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001947 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948 copied += copy;
1949 bytes -= copy;
1950 vaddr += copy;
1951 iov++;
1952
NeilBrown01408c42006-06-25 05:47:58 -07001953 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 }
1956 return copied - left;
1957}
1958
1959/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960 * Performs necessary checks before doing a write
1961 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001962 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 * Returns appropriate error code that caller should return or
1964 * zero in case that write should be allowed.
1965 */
1966inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1967{
1968 struct inode *inode = file->f_mapping->host;
1969 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1970
1971 if (unlikely(*pos < 0))
1972 return -EINVAL;
1973
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974 if (!isblk) {
1975 /* FIXME: this is for backwards compatibility with 2.4 */
1976 if (file->f_flags & O_APPEND)
1977 *pos = i_size_read(inode);
1978
1979 if (limit != RLIM_INFINITY) {
1980 if (*pos >= limit) {
1981 send_sig(SIGXFSZ, current, 0);
1982 return -EFBIG;
1983 }
1984 if (*count > limit - (typeof(limit))*pos) {
1985 *count = limit - (typeof(limit))*pos;
1986 }
1987 }
1988 }
1989
1990 /*
1991 * LFS rule
1992 */
1993 if (unlikely(*pos + *count > MAX_NON_LFS &&
1994 !(file->f_flags & O_LARGEFILE))) {
1995 if (*pos >= MAX_NON_LFS) {
1996 send_sig(SIGXFSZ, current, 0);
1997 return -EFBIG;
1998 }
1999 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2000 *count = MAX_NON_LFS - (unsigned long)*pos;
2001 }
2002 }
2003
2004 /*
2005 * Are we about to exceed the fs block limit ?
2006 *
2007 * If we have written data it becomes a short write. If we have
2008 * exceeded without writing data we send a signal and return EFBIG.
2009 * Linus frestrict idea will clean these up nicely..
2010 */
2011 if (likely(!isblk)) {
2012 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2013 if (*count || *pos > inode->i_sb->s_maxbytes) {
2014 send_sig(SIGXFSZ, current, 0);
2015 return -EFBIG;
2016 }
2017 /* zero-length writes at ->s_maxbytes are OK */
2018 }
2019
2020 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2021 *count = inode->i_sb->s_maxbytes - *pos;
2022 } else {
David Howells93614012006-09-30 20:45:40 +02002023#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024 loff_t isize;
2025 if (bdev_read_only(I_BDEV(inode)))
2026 return -EPERM;
2027 isize = i_size_read(inode);
2028 if (*pos >= isize) {
2029 if (*count || *pos > isize)
2030 return -ENOSPC;
2031 }
2032
2033 if (*pos + *count > isize)
2034 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002035#else
2036 return -EPERM;
2037#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002038 }
2039 return 0;
2040}
2041EXPORT_SYMBOL(generic_write_checks);
2042
2043ssize_t
2044generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2045 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2046 size_t count, size_t ocount)
2047{
2048 struct file *file = iocb->ki_filp;
2049 struct address_space *mapping = file->f_mapping;
2050 struct inode *inode = mapping->host;
2051 ssize_t written;
2052
2053 if (count != ocount)
2054 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2055
2056 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2057 if (written > 0) {
2058 loff_t end = pos + written;
2059 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2060 i_size_write(inode, end);
2061 mark_inode_dirty(inode);
2062 }
2063 *ppos = end;
2064 }
2065
2066 /*
2067 * Sync the fs metadata but not the minor inode changes and
2068 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002069 * i_mutex is held, which protects generic_osync_inode() from
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 * livelocking.
2071 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07002072 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2073 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2074 if (err < 0)
2075 written = err;
2076 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077 if (written == count && !is_sync_kiocb(iocb))
2078 written = -EIOCBQUEUED;
2079 return written;
2080}
2081EXPORT_SYMBOL(generic_file_direct_write);
2082
2083ssize_t
2084generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2085 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2086 size_t count, ssize_t written)
2087{
2088 struct file *file = iocb->ki_filp;
2089 struct address_space * mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002090 const struct address_space_operations *a_ops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091 struct inode *inode = mapping->host;
2092 long status = 0;
2093 struct page *page;
2094 struct page *cached_page = NULL;
2095 size_t bytes;
2096 struct pagevec lru_pvec;
2097 const struct iovec *cur_iov = iov; /* current iovec */
2098 size_t iov_base = 0; /* offset in the current iovec */
2099 char __user *buf;
2100
2101 pagevec_init(&lru_pvec, 0);
2102
2103 /*
2104 * handle partial DIO write. Adjust cur_iov if needed.
2105 */
2106 if (likely(nr_segs == 1))
2107 buf = iov->iov_base + written;
2108 else {
2109 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002110 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111 }
2112
2113 do {
2114 unsigned long index;
2115 unsigned long offset;
2116 size_t copied;
2117
2118 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2119 index = pos >> PAGE_CACHE_SHIFT;
2120 bytes = PAGE_CACHE_SIZE - offset;
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002121
2122 /* Limit the size of the copy to the caller's write size */
2123 bytes = min(bytes, count);
2124
2125 /*
2126 * Limit the size of the copy to that of the current segment,
2127 * because fault_in_pages_readable() doesn't know how to walk
2128 * segments.
2129 */
2130 bytes = min(bytes, cur_iov->iov_len - iov_base);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131
2132 /*
2133 * Bring in the user page that we will copy from _first_.
2134 * Otherwise there's a nasty deadlock on copying from the
2135 * same page as we're writing to, without it being marked
2136 * up-to-date.
2137 */
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002138 fault_in_pages_readable(buf, bytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139
2140 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2141 if (!page) {
2142 status = -ENOMEM;
2143 break;
2144 }
2145
Andrew Morton81b0c872006-06-29 02:24:26 -07002146 if (unlikely(bytes == 0)) {
2147 status = 0;
2148 copied = 0;
2149 goto zero_length_segment;
2150 }
2151
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2153 if (unlikely(status)) {
2154 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08002155
2156 if (status != AOP_TRUNCATED_PAGE)
2157 unlock_page(page);
2158 page_cache_release(page);
2159 if (status == AOP_TRUNCATED_PAGE)
2160 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 /*
2162 * prepare_write() may have instantiated a few blocks
2163 * outside i_size. Trim these off again.
2164 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 if (pos + bytes > isize)
2166 vmtruncate(inode, isize);
2167 break;
2168 }
2169 if (likely(nr_segs == 1))
2170 copied = filemap_copy_from_user(page, offset,
2171 buf, bytes);
2172 else
2173 copied = filemap_copy_from_user_iovec(page, offset,
2174 cur_iov, iov_base, bytes);
2175 flush_dcache_page(page);
2176 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08002177 if (status == AOP_TRUNCATED_PAGE) {
2178 page_cache_release(page);
2179 continue;
2180 }
Andrew Morton81b0c872006-06-29 02:24:26 -07002181zero_length_segment:
2182 if (likely(copied >= 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 if (!status)
2184 status = copied;
2185
2186 if (status >= 0) {
2187 written += status;
2188 count -= status;
2189 pos += status;
2190 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002191 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 filemap_set_next_iovec(&cur_iov,
2193 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002194 if (count)
2195 buf = cur_iov->iov_base +
2196 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002197 } else {
2198 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002199 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200 }
2201 }
2202 if (unlikely(copied != bytes))
2203 if (status >= 0)
2204 status = -EFAULT;
2205 unlock_page(page);
2206 mark_page_accessed(page);
2207 page_cache_release(page);
2208 if (status < 0)
2209 break;
2210 balance_dirty_pages_ratelimited(mapping);
2211 cond_resched();
2212 } while (count);
2213 *ppos = pos;
2214
2215 if (cached_page)
2216 page_cache_release(cached_page);
2217
2218 /*
2219 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2220 */
2221 if (likely(status >= 0)) {
2222 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2223 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2224 status = generic_osync_inode(inode, mapping,
2225 OSYNC_METADATA|OSYNC_DATA);
2226 }
2227 }
2228
2229 /*
2230 * If we get here for O_DIRECT writes then we must have fallen through
2231 * to buffered writes (block instantiation inside i_size). So we sync
2232 * the file data here, to try to honour O_DIRECT expectations.
2233 */
2234 if (unlikely(file->f_flags & O_DIRECT) && written)
2235 status = filemap_write_and_wait(mapping);
2236
2237 pagevec_lru_add(&lru_pvec);
2238 return written ? written : status;
2239}
2240EXPORT_SYMBOL(generic_file_buffered_write);
2241
Adrian Bunk5ce78522005-09-10 00:26:28 -07002242static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2244 unsigned long nr_segs, loff_t *ppos)
2245{
2246 struct file *file = iocb->ki_filp;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002247 const struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002248 size_t ocount; /* original count */
2249 size_t count; /* after file limit checks */
2250 struct inode *inode = mapping->host;
2251 unsigned long seg;
2252 loff_t pos;
2253 ssize_t written;
2254 ssize_t err;
2255
2256 ocount = 0;
2257 for (seg = 0; seg < nr_segs; seg++) {
2258 const struct iovec *iv = &iov[seg];
2259
2260 /*
2261 * If any segment has a negative length, or the cumulative
2262 * length ever wraps negative then return -EINVAL.
2263 */
2264 ocount += iv->iov_len;
2265 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2266 return -EINVAL;
2267 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2268 continue;
2269 if (seg == 0)
2270 return -EFAULT;
2271 nr_segs = seg;
2272 ocount -= iv->iov_len; /* This segment is no good */
2273 break;
2274 }
2275
2276 count = ocount;
2277 pos = *ppos;
2278
2279 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2280
2281 /* We can write back this queue in page reclaim */
2282 current->backing_dev_info = mapping->backing_dev_info;
2283 written = 0;
2284
2285 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2286 if (err)
2287 goto out;
2288
2289 if (count == 0)
2290 goto out;
2291
2292 err = remove_suid(file->f_dentry);
2293 if (err)
2294 goto out;
2295
Christoph Hellwig870f4812006-01-09 20:52:01 -08002296 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002297
2298 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2299 if (unlikely(file->f_flags & O_DIRECT)) {
2300 written = generic_file_direct_write(iocb, iov,
2301 &nr_segs, pos, ppos, count, ocount);
2302 if (written < 0 || written == count)
2303 goto out;
2304 /*
2305 * direct-io write to a hole: fall through to buffered I/O
2306 * for completing the rest of the request.
2307 */
2308 pos += written;
2309 count -= written;
2310 }
2311
2312 written = generic_file_buffered_write(iocb, iov, nr_segs,
2313 pos, ppos, count, written);
2314out:
2315 current->backing_dev_info = NULL;
2316 return written ? written : err;
2317}
2318EXPORT_SYMBOL(generic_file_aio_write_nolock);
2319
2320ssize_t
2321generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2322 unsigned long nr_segs, loff_t *ppos)
2323{
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;
2328 loff_t pos = *ppos;
2329
2330 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs, ppos);
2331
2332 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2333 int err;
2334
2335 err = sync_page_range_nolock(inode, mapping, pos, ret);
2336 if (err < 0)
2337 ret = err;
2338 }
2339 return ret;
2340}
2341
Adrian Bunk5ce78522005-09-10 00:26:28 -07002342static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002343__generic_file_write_nolock(struct file *file, const struct iovec *iov,
2344 unsigned long nr_segs, loff_t *ppos)
2345{
2346 struct kiocb kiocb;
2347 ssize_t ret;
2348
2349 init_sync_kiocb(&kiocb, file);
2350 ret = __generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2351 if (ret == -EIOCBQUEUED)
2352 ret = wait_on_sync_kiocb(&kiocb);
2353 return ret;
2354}
2355
2356ssize_t
2357generic_file_write_nolock(struct file *file, const struct iovec *iov,
2358 unsigned long nr_segs, loff_t *ppos)
2359{
2360 struct kiocb kiocb;
2361 ssize_t ret;
2362
2363 init_sync_kiocb(&kiocb, file);
2364 ret = generic_file_aio_write_nolock(&kiocb, iov, nr_segs, ppos);
2365 if (-EIOCBQUEUED == ret)
2366 ret = wait_on_sync_kiocb(&kiocb);
2367 return ret;
2368}
2369EXPORT_SYMBOL(generic_file_write_nolock);
2370
2371ssize_t generic_file_aio_write(struct kiocb *iocb, const char __user *buf,
2372 size_t count, loff_t pos)
2373{
2374 struct file *file = iocb->ki_filp;
2375 struct address_space *mapping = file->f_mapping;
2376 struct inode *inode = mapping->host;
2377 ssize_t ret;
2378 struct iovec local_iov = { .iov_base = (void __user *)buf,
2379 .iov_len = count };
2380
2381 BUG_ON(iocb->ki_pos != pos);
2382
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002383 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384 ret = __generic_file_aio_write_nolock(iocb, &local_iov, 1,
2385 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002386 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002387
2388 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2389 ssize_t err;
2390
2391 err = sync_page_range(inode, mapping, pos, ret);
2392 if (err < 0)
2393 ret = err;
2394 }
2395 return ret;
2396}
2397EXPORT_SYMBOL(generic_file_aio_write);
2398
2399ssize_t generic_file_write(struct file *file, const char __user *buf,
2400 size_t count, loff_t *ppos)
2401{
2402 struct address_space *mapping = file->f_mapping;
2403 struct inode *inode = mapping->host;
2404 ssize_t ret;
2405 struct iovec local_iov = { .iov_base = (void __user *)buf,
2406 .iov_len = count };
2407
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002408 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409 ret = __generic_file_write_nolock(file, &local_iov, 1, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002410 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411
2412 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2413 ssize_t err;
2414
2415 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2416 if (err < 0)
2417 ret = err;
2418 }
2419 return ret;
2420}
2421EXPORT_SYMBOL(generic_file_write);
2422
2423ssize_t generic_file_readv(struct file *filp, const struct iovec *iov,
2424 unsigned long nr_segs, loff_t *ppos)
2425{
2426 struct kiocb kiocb;
2427 ssize_t ret;
2428
2429 init_sync_kiocb(&kiocb, filp);
2430 ret = __generic_file_aio_read(&kiocb, iov, nr_segs, ppos);
2431 if (-EIOCBQUEUED == ret)
2432 ret = wait_on_sync_kiocb(&kiocb);
2433 return ret;
2434}
2435EXPORT_SYMBOL(generic_file_readv);
2436
2437ssize_t generic_file_writev(struct file *file, const struct iovec *iov,
2438 unsigned long nr_segs, loff_t *ppos)
2439{
2440 struct address_space *mapping = file->f_mapping;
2441 struct inode *inode = mapping->host;
2442 ssize_t ret;
2443
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002444 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 ret = __generic_file_write_nolock(file, iov, nr_segs, ppos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002446 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002447
2448 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2449 int err;
2450
2451 err = sync_page_range(inode, mapping, *ppos - ret, ret);
2452 if (err < 0)
2453 ret = err;
2454 }
2455 return ret;
2456}
2457EXPORT_SYMBOL(generic_file_writev);
2458
2459/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002460 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461 * went wrong during pagecache shootdown.
2462 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002463static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002464generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2465 loff_t offset, unsigned long nr_segs)
2466{
2467 struct file *file = iocb->ki_filp;
2468 struct address_space *mapping = file->f_mapping;
2469 ssize_t retval;
2470 size_t write_len = 0;
2471
2472 /*
2473 * If it's a write, unmap all mmappings of the file up-front. This
2474 * will cause any pte dirty bits to be propagated into the pageframes
2475 * for the subsequent filemap_write_and_wait().
2476 */
2477 if (rw == WRITE) {
2478 write_len = iov_length(iov, nr_segs);
2479 if (mapping_mapped(mapping))
2480 unmap_mapping_range(mapping, offset, write_len, 0);
2481 }
2482
2483 retval = filemap_write_and_wait(mapping);
2484 if (retval == 0) {
2485 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2486 offset, nr_segs);
2487 if (rw == WRITE && mapping->nrpages) {
2488 pgoff_t end = (offset + write_len - 1)
2489 >> PAGE_CACHE_SHIFT;
2490 int err = invalidate_inode_pages2_range(mapping,
2491 offset >> PAGE_CACHE_SHIFT, end);
2492 if (err)
2493 retval = err;
2494 }
2495 }
2496 return retval;
2497}
David Howellscf9a2ae2006-08-29 19:05:54 +01002498
2499/**
2500 * try_to_release_page() - release old fs-specific metadata on a page
2501 *
2502 * @page: the page which the kernel is trying to free
2503 * @gfp_mask: memory allocation flags (and I/O mode)
2504 *
2505 * The address_space is to try to release any data against the page
2506 * (presumably at page->private). If the release was successful, return `1'.
2507 * Otherwise return zero.
2508 *
2509 * The @gfp_mask argument specifies whether I/O may be performed to release
2510 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2511 *
2512 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2513 */
2514int try_to_release_page(struct page *page, gfp_t gfp_mask)
2515{
2516 struct address_space * const mapping = page->mapping;
2517
2518 BUG_ON(!PageLocked(page));
2519 if (PageWriteback(page))
2520 return 0;
2521
2522 if (mapping && mapping->a_ops->releasepage)
2523 return mapping->a_ops->releasepage(page, gfp_mask);
2524 return try_to_free_buffers(page);
2525}
2526
2527EXPORT_SYMBOL(try_to_release_page);