blob: 7b84dc814347544d68ab662f11691b25ca54ac3a [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 *
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
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/**
609 * find_trylock_page - find and lock a page
610 * @mapping: the address_space to search
611 * @offset: the page index
612 *
613 * Same as find_get_page(), but trylock it instead of incrementing the count.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 */
615struct page *find_trylock_page(struct address_space *mapping, unsigned long offset)
616{
617 struct page *page;
618
619 read_lock_irq(&mapping->tree_lock);
620 page = radix_tree_lookup(&mapping->page_tree, offset);
621 if (page && TestSetPageLocked(page))
622 page = NULL;
623 read_unlock_irq(&mapping->tree_lock);
624 return page;
625}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626EXPORT_SYMBOL(find_trylock_page);
627
628/**
629 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700630 * @mapping: the address_space to search
631 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 *
633 * Locates the desired pagecache page, locks it, increments its reference
634 * count and returns its address.
635 *
636 * Returns zero if the page was not present. find_lock_page() may sleep.
637 */
638struct page *find_lock_page(struct address_space *mapping,
639 unsigned long offset)
640{
641 struct page *page;
642
643 read_lock_irq(&mapping->tree_lock);
644repeat:
645 page = radix_tree_lookup(&mapping->page_tree, offset);
646 if (page) {
647 page_cache_get(page);
648 if (TestSetPageLocked(page)) {
649 read_unlock_irq(&mapping->tree_lock);
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800650 __lock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 read_lock_irq(&mapping->tree_lock);
652
653 /* Has the page been truncated while we slept? */
Nikita Danilovbbfbb7c2006-01-06 00:11:08 -0800654 if (unlikely(page->mapping != mapping ||
655 page->index != offset)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 unlock_page(page);
657 page_cache_release(page);
658 goto repeat;
659 }
660 }
661 }
662 read_unlock_irq(&mapping->tree_lock);
663 return page;
664}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665EXPORT_SYMBOL(find_lock_page);
666
667/**
668 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700669 * @mapping: the page's address_space
670 * @index: the page's index into the mapping
671 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672 *
673 * Locates a page in the pagecache. If the page is not present, a new page
674 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
675 * LRU list. The returned page is locked and has its reference count
676 * incremented.
677 *
678 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
679 * allocation!
680 *
681 * find_or_create_page() returns the desired page's address, or zero on
682 * memory exhaustion.
683 */
684struct page *find_or_create_page(struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400685 unsigned long index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686{
687 struct page *page, *cached_page = NULL;
688 int err;
689repeat:
690 page = find_lock_page(mapping, index);
691 if (!page) {
692 if (!cached_page) {
693 cached_page = alloc_page(gfp_mask);
694 if (!cached_page)
695 return NULL;
696 }
697 err = add_to_page_cache_lru(cached_page, mapping,
698 index, gfp_mask);
699 if (!err) {
700 page = cached_page;
701 cached_page = NULL;
702 } else if (err == -EEXIST)
703 goto repeat;
704 }
705 if (cached_page)
706 page_cache_release(cached_page);
707 return page;
708}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709EXPORT_SYMBOL(find_or_create_page);
710
711/**
712 * find_get_pages - gang pagecache lookup
713 * @mapping: The address_space to search
714 * @start: The starting page index
715 * @nr_pages: The maximum number of pages
716 * @pages: Where the resulting pages are placed
717 *
718 * find_get_pages() will search for and return a group of up to
719 * @nr_pages pages in the mapping. The pages are placed at @pages.
720 * find_get_pages() takes a reference against the returned pages.
721 *
722 * The search returns a group of mapping-contiguous pages with ascending
723 * indexes. There may be holes in the indices due to not-present pages.
724 *
725 * find_get_pages() returns the number of pages which were found.
726 */
727unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
728 unsigned int nr_pages, struct page **pages)
729{
730 unsigned int i;
731 unsigned int ret;
732
733 read_lock_irq(&mapping->tree_lock);
734 ret = radix_tree_gang_lookup(&mapping->page_tree,
735 (void **)pages, start, nr_pages);
736 for (i = 0; i < ret; i++)
737 page_cache_get(pages[i]);
738 read_unlock_irq(&mapping->tree_lock);
739 return ret;
740}
741
Jens Axboeebf43502006-04-27 08:46:01 +0200742/**
743 * find_get_pages_contig - gang contiguous pagecache lookup
744 * @mapping: The address_space to search
745 * @index: The starting page index
746 * @nr_pages: The maximum number of pages
747 * @pages: Where the resulting pages are placed
748 *
749 * find_get_pages_contig() works exactly like find_get_pages(), except
750 * that the returned number of pages are guaranteed to be contiguous.
751 *
752 * find_get_pages_contig() returns the number of pages which were found.
753 */
754unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
755 unsigned int nr_pages, struct page **pages)
756{
757 unsigned int i;
758 unsigned int ret;
759
760 read_lock_irq(&mapping->tree_lock);
761 ret = radix_tree_gang_lookup(&mapping->page_tree,
762 (void **)pages, index, nr_pages);
763 for (i = 0; i < ret; i++) {
764 if (pages[i]->mapping == NULL || pages[i]->index != index)
765 break;
766
767 page_cache_get(pages[i]);
768 index++;
769 }
770 read_unlock_irq(&mapping->tree_lock);
771 return i;
772}
773
Randy Dunlap485bb992006-06-23 02:03:49 -0700774/**
775 * find_get_pages_tag - find and return pages that match @tag
776 * @mapping: the address_space to search
777 * @index: the starting page index
778 * @tag: the tag index
779 * @nr_pages: the maximum number of pages
780 * @pages: where the resulting pages are placed
781 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700783 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 */
785unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
786 int tag, unsigned int nr_pages, struct page **pages)
787{
788 unsigned int i;
789 unsigned int ret;
790
791 read_lock_irq(&mapping->tree_lock);
792 ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
793 (void **)pages, *index, nr_pages, tag);
794 for (i = 0; i < ret; i++)
795 page_cache_get(pages[i]);
796 if (ret)
797 *index = pages[ret - 1]->index + 1;
798 read_unlock_irq(&mapping->tree_lock);
799 return ret;
800}
801
Randy Dunlap485bb992006-06-23 02:03:49 -0700802/**
803 * grab_cache_page_nowait - returns locked page at given index in given cache
804 * @mapping: target address_space
805 * @index: the page index
806 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 * Same as grab_cache_page, but do not wait if the page is unavailable.
808 * This is intended for speculative data generators, where the data can
809 * be regenerated if the page couldn't be grabbed. This routine should
810 * be safe to call while holding the lock for another page.
811 *
812 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
813 * and deadlock against the caller's locked page.
814 */
815struct page *
816grab_cache_page_nowait(struct address_space *mapping, unsigned long index)
817{
818 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819
820 if (page) {
821 if (!TestSetPageLocked(page))
822 return page;
823 page_cache_release(page);
824 return NULL;
825 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700826 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
827 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 page_cache_release(page);
829 page = NULL;
830 }
831 return page;
832}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833EXPORT_SYMBOL(grab_cache_page_nowait);
834
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700835/*
836 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
837 * a _large_ part of the i/o request. Imagine the worst scenario:
838 *
839 * ---R__________________________________________B__________
840 * ^ reading here ^ bad block(assume 4k)
841 *
842 * read(R) => miss => readahead(R...B) => media error => frustrating retries
843 * => failing the whole request => read(R) => read(R+1) =>
844 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
845 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
846 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
847 *
848 * It is going insane. Fix it by quickly scaling down the readahead size.
849 */
850static void shrink_readahead_size_eio(struct file *filp,
851 struct file_ra_state *ra)
852{
853 if (!ra->ra_pages)
854 return;
855
856 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700857}
858
Randy Dunlap485bb992006-06-23 02:03:49 -0700859/**
860 * do_generic_mapping_read - generic file read routine
861 * @mapping: address_space to be read
862 * @_ra: file's readahead state
863 * @filp: the file to read
864 * @ppos: current file position
865 * @desc: read_descriptor
866 * @actor: read method
867 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700869 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700870 *
871 * This is really ugly. But the goto's actually try to clarify some
872 * of the logic when it comes to error handling etc.
873 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700874 * Note the struct file* is only passed for the use of readpage.
875 * It may be NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 */
877void do_generic_mapping_read(struct address_space *mapping,
878 struct file_ra_state *_ra,
879 struct file *filp,
880 loff_t *ppos,
881 read_descriptor_t *desc,
882 read_actor_t actor)
883{
884 struct inode *inode = mapping->host;
885 unsigned long index;
886 unsigned long end_index;
887 unsigned long offset;
888 unsigned long last_index;
889 unsigned long next_index;
890 unsigned long prev_index;
891 loff_t isize;
892 struct page *cached_page;
893 int error;
894 struct file_ra_state ra = *_ra;
895
896 cached_page = NULL;
897 index = *ppos >> PAGE_CACHE_SHIFT;
898 next_index = index;
899 prev_index = ra.prev_page;
900 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
901 offset = *ppos & ~PAGE_CACHE_MASK;
902
903 isize = i_size_read(inode);
904 if (!isize)
905 goto out;
906
907 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
908 for (;;) {
909 struct page *page;
910 unsigned long nr, ret;
911
912 /* nr is the maximum number of bytes to copy from this page */
913 nr = PAGE_CACHE_SIZE;
914 if (index >= end_index) {
915 if (index > end_index)
916 goto out;
917 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
918 if (nr <= offset) {
919 goto out;
920 }
921 }
922 nr = nr - offset;
923
924 cond_resched();
925 if (index == next_index)
926 next_index = page_cache_readahead(mapping, &ra, filp,
927 index, last_index - index);
928
929find_page:
930 page = find_get_page(mapping, index);
931 if (unlikely(page == NULL)) {
932 handle_ra_miss(mapping, &ra, index);
933 goto no_cached_page;
934 }
935 if (!PageUptodate(page))
936 goto page_not_up_to_date;
937page_ok:
938
939 /* If users can be writing to this page using arbitrary
940 * virtual addresses, take care about potential aliasing
941 * before reading the page on the kernel side.
942 */
943 if (mapping_writably_mapped(mapping))
944 flush_dcache_page(page);
945
946 /*
947 * When (part of) the same page is read multiple times
948 * in succession, only mark it as accessed the first time.
949 */
950 if (prev_index != index)
951 mark_page_accessed(page);
952 prev_index = index;
953
954 /*
955 * Ok, we have the page, and it's up-to-date, so
956 * now we can copy it to user space...
957 *
958 * The actor routine returns how many bytes were actually used..
959 * NOTE! This may not be the same as how much of a user buffer
960 * we filled up (we may be padding etc), so we can only update
961 * "pos" here (the actor routine has to update the user buffer
962 * pointers and the remaining count).
963 */
964 ret = actor(desc, page, offset, nr);
965 offset += ret;
966 index += offset >> PAGE_CACHE_SHIFT;
967 offset &= ~PAGE_CACHE_MASK;
968
969 page_cache_release(page);
970 if (ret == nr && desc->count)
971 continue;
972 goto out;
973
974page_not_up_to_date:
975 /* Get exclusive access to the page ... */
976 lock_page(page);
977
Nick Pigginda6052f2006-09-25 23:31:35 -0700978 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 if (!page->mapping) {
980 unlock_page(page);
981 page_cache_release(page);
982 continue;
983 }
984
985 /* Did somebody else fill it already? */
986 if (PageUptodate(page)) {
987 unlock_page(page);
988 goto page_ok;
989 }
990
991readpage:
992 /* Start the actual read. The read will unlock the page. */
993 error = mapping->a_ops->readpage(filp, page);
994
Zach Brown994fc28c2005-12-15 14:28:17 -0800995 if (unlikely(error)) {
996 if (error == AOP_TRUNCATED_PAGE) {
997 page_cache_release(page);
998 goto find_page;
999 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001001 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002
1003 if (!PageUptodate(page)) {
1004 lock_page(page);
1005 if (!PageUptodate(page)) {
1006 if (page->mapping == NULL) {
1007 /*
1008 * invalidate_inode_pages got it
1009 */
1010 unlock_page(page);
1011 page_cache_release(page);
1012 goto find_page;
1013 }
1014 unlock_page(page);
1015 error = -EIO;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001016 shrink_readahead_size_eio(filp, &ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 goto readpage_error;
1018 }
1019 unlock_page(page);
1020 }
1021
1022 /*
1023 * i_size must be checked after we have done ->readpage.
1024 *
1025 * Checking i_size after the readpage allows us to calculate
1026 * the correct value for "nr", which means the zero-filled
1027 * part of the page is not copied back to userspace (unless
1028 * another truncate extends the file - this is desired though).
1029 */
1030 isize = i_size_read(inode);
1031 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1032 if (unlikely(!isize || index > end_index)) {
1033 page_cache_release(page);
1034 goto out;
1035 }
1036
1037 /* nr is the maximum number of bytes to copy from this page */
1038 nr = PAGE_CACHE_SIZE;
1039 if (index == end_index) {
1040 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1041 if (nr <= offset) {
1042 page_cache_release(page);
1043 goto out;
1044 }
1045 }
1046 nr = nr - offset;
1047 goto page_ok;
1048
1049readpage_error:
1050 /* UHHUH! A synchronous read error occurred. Report it */
1051 desc->error = error;
1052 page_cache_release(page);
1053 goto out;
1054
1055no_cached_page:
1056 /*
1057 * Ok, it wasn't cached, so we need to create a new
1058 * page..
1059 */
1060 if (!cached_page) {
1061 cached_page = page_cache_alloc_cold(mapping);
1062 if (!cached_page) {
1063 desc->error = -ENOMEM;
1064 goto out;
1065 }
1066 }
1067 error = add_to_page_cache_lru(cached_page, mapping,
1068 index, GFP_KERNEL);
1069 if (error) {
1070 if (error == -EEXIST)
1071 goto find_page;
1072 desc->error = error;
1073 goto out;
1074 }
1075 page = cached_page;
1076 cached_page = NULL;
1077 goto readpage;
1078 }
1079
1080out:
1081 *_ra = ra;
1082
1083 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1084 if (cached_page)
1085 page_cache_release(cached_page);
1086 if (filp)
1087 file_accessed(filp);
1088}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089EXPORT_SYMBOL(do_generic_mapping_read);
1090
1091int file_read_actor(read_descriptor_t *desc, struct page *page,
1092 unsigned long offset, unsigned long size)
1093{
1094 char *kaddr;
1095 unsigned long left, count = desc->count;
1096
1097 if (size > count)
1098 size = count;
1099
1100 /*
1101 * Faults on the destination of a read are common, so do it before
1102 * taking the kmap.
1103 */
1104 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1105 kaddr = kmap_atomic(page, KM_USER0);
1106 left = __copy_to_user_inatomic(desc->arg.buf,
1107 kaddr + offset, size);
1108 kunmap_atomic(kaddr, KM_USER0);
1109 if (left == 0)
1110 goto success;
1111 }
1112
1113 /* Do it the slow way */
1114 kaddr = kmap(page);
1115 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1116 kunmap(page);
1117
1118 if (left) {
1119 size -= left;
1120 desc->error = -EFAULT;
1121 }
1122success:
1123 desc->count = count - size;
1124 desc->written += size;
1125 desc->arg.buf += size;
1126 return size;
1127}
1128
Randy Dunlap485bb992006-06-23 02:03:49 -07001129/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001130 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001131 * @iocb: kernel I/O control block
1132 * @iov: io vector request
1133 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001134 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001135 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136 * This is the "read()" routine for all filesystems
1137 * that can use the page cache directly.
1138 */
1139ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001140generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1141 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142{
1143 struct file *filp = iocb->ki_filp;
1144 ssize_t retval;
1145 unsigned long seg;
1146 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001147 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148
1149 count = 0;
1150 for (seg = 0; seg < nr_segs; seg++) {
1151 const struct iovec *iv = &iov[seg];
1152
1153 /*
1154 * If any segment has a negative length, or the cumulative
1155 * length ever wraps negative then return -EINVAL.
1156 */
1157 count += iv->iov_len;
1158 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
1159 return -EINVAL;
1160 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
1161 continue;
1162 if (seg == 0)
1163 return -EFAULT;
1164 nr_segs = seg;
1165 count -= iv->iov_len; /* This segment is no good */
1166 break;
1167 }
1168
1169 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1170 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001171 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 struct address_space *mapping;
1173 struct inode *inode;
1174
1175 mapping = filp->f_mapping;
1176 inode = mapping->host;
1177 retval = 0;
1178 if (!count)
1179 goto out; /* skip atime */
1180 size = i_size_read(inode);
1181 if (pos < size) {
1182 retval = generic_file_direct_IO(READ, iocb,
1183 iov, pos, nr_segs);
Suparna Bhattacharyab5c44c22005-05-21 16:33:36 -07001184 if (retval > 0 && !is_sync_kiocb(iocb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185 retval = -EIOCBQUEUED;
1186 if (retval > 0)
1187 *ppos = pos + retval;
1188 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001189 if (likely(retval != 0)) {
Steven Whitehouse3f1a9aa2006-09-27 14:52:48 -04001190 file_accessed(filp);
Steven Whitehousea9e5f4d2006-07-25 17:24:12 -04001191 goto out;
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001192 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 }
1194
1195 retval = 0;
1196 if (count) {
1197 for (seg = 0; seg < nr_segs; seg++) {
1198 read_descriptor_t desc;
1199
1200 desc.written = 0;
1201 desc.arg.buf = iov[seg].iov_base;
1202 desc.count = iov[seg].iov_len;
1203 if (desc.count == 0)
1204 continue;
1205 desc.error = 0;
1206 do_generic_file_read(filp,ppos,&desc,file_read_actor);
1207 retval += desc.written;
Tejun Heo39e88ca2005-10-30 15:02:40 -08001208 if (desc.error) {
1209 retval = retval ?: desc.error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 break;
1211 }
1212 }
1213 }
1214out:
1215 return retval;
1216}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217EXPORT_SYMBOL(generic_file_aio_read);
1218
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219int file_send_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size)
1220{
1221 ssize_t written;
1222 unsigned long count = desc->count;
1223 struct file *file = desc->arg.data;
1224
1225 if (size > count)
1226 size = count;
1227
1228 written = file->f_op->sendpage(file, page, offset,
1229 size, &file->f_pos, size<count);
1230 if (written < 0) {
1231 desc->error = written;
1232 written = 0;
1233 }
1234 desc->count = count - written;
1235 desc->written += written;
1236 return written;
1237}
1238
1239ssize_t generic_file_sendfile(struct file *in_file, loff_t *ppos,
1240 size_t count, read_actor_t actor, void *target)
1241{
1242 read_descriptor_t desc;
1243
1244 if (!count)
1245 return 0;
1246
1247 desc.written = 0;
1248 desc.count = count;
1249 desc.arg.data = target;
1250 desc.error = 0;
1251
1252 do_generic_file_read(in_file, ppos, &desc, actor);
1253 if (desc.written)
1254 return desc.written;
1255 return desc.error;
1256}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257EXPORT_SYMBOL(generic_file_sendfile);
1258
1259static ssize_t
1260do_readahead(struct address_space *mapping, struct file *filp,
1261 unsigned long index, unsigned long nr)
1262{
1263 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1264 return -EINVAL;
1265
1266 force_page_cache_readahead(mapping, filp, index,
1267 max_sane_readahead(nr));
1268 return 0;
1269}
1270
1271asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1272{
1273 ssize_t ret;
1274 struct file *file;
1275
1276 ret = -EBADF;
1277 file = fget(fd);
1278 if (file) {
1279 if (file->f_mode & FMODE_READ) {
1280 struct address_space *mapping = file->f_mapping;
1281 unsigned long start = offset >> PAGE_CACHE_SHIFT;
1282 unsigned long end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
1283 unsigned long len = end - start + 1;
1284 ret = do_readahead(mapping, file, start, len);
1285 }
1286 fput(file);
1287 }
1288 return ret;
1289}
1290
1291#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001292static int FASTCALL(page_cache_read(struct file * file, unsigned long offset));
1293/**
1294 * page_cache_read - adds requested page to the page cache if not already there
1295 * @file: file to read
1296 * @offset: page index
1297 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 * This adds the requested page to the page cache if it isn't already there,
1299 * and schedules an I/O to read in its contents from disk.
1300 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301static int fastcall page_cache_read(struct file * file, unsigned long offset)
1302{
1303 struct address_space *mapping = file->f_mapping;
1304 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001305 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
Zach Brown994fc28c2005-12-15 14:28:17 -08001307 do {
1308 page = page_cache_alloc_cold(mapping);
1309 if (!page)
1310 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311
Zach Brown994fc28c2005-12-15 14:28:17 -08001312 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1313 if (ret == 0)
1314 ret = mapping->a_ops->readpage(file, page);
1315 else if (ret == -EEXIST)
1316 ret = 0; /* losing race to add is OK */
1317
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319
Zach Brown994fc28c2005-12-15 14:28:17 -08001320 } while (ret == AOP_TRUNCATED_PAGE);
1321
1322 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323}
1324
1325#define MMAP_LOTSAMISS (100)
1326
Randy Dunlap485bb992006-06-23 02:03:49 -07001327/**
1328 * filemap_nopage - read in file data for page fault handling
1329 * @area: the applicable vm_area
1330 * @address: target address to read in
1331 * @type: returned with VM_FAULT_{MINOR,MAJOR} if not %NULL
1332 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 * filemap_nopage() is invoked via the vma operations vector for a
1334 * mapped memory region to read in file data during a page fault.
1335 *
1336 * The goto's are kind of ugly, but this streamlines the normal case of having
1337 * it in the page cache, and handles the special cases reasonably without
1338 * having a lot of duplicated code.
1339 */
1340struct page *filemap_nopage(struct vm_area_struct *area,
1341 unsigned long address, int *type)
1342{
1343 int error;
1344 struct file *file = area->vm_file;
1345 struct address_space *mapping = file->f_mapping;
1346 struct file_ra_state *ra = &file->f_ra;
1347 struct inode *inode = mapping->host;
1348 struct page *page;
1349 unsigned long size, pgoff;
1350 int did_readaround = 0, majmin = VM_FAULT_MINOR;
1351
1352 pgoff = ((address-area->vm_start) >> PAGE_CACHE_SHIFT) + area->vm_pgoff;
1353
1354retry_all:
1355 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1356 if (pgoff >= size)
1357 goto outside_data_content;
1358
1359 /* If we don't want any read-ahead, don't bother */
1360 if (VM_RandomReadHint(area))
1361 goto no_cached_page;
1362
1363 /*
1364 * The readahead code wants to be told about each and every page
1365 * so it can build and shrink its windows appropriately
1366 *
1367 * For sequential accesses, we use the generic readahead logic.
1368 */
1369 if (VM_SequentialReadHint(area))
1370 page_cache_readahead(mapping, ra, file, pgoff, 1);
1371
1372 /*
1373 * Do we have something in the page cache already?
1374 */
1375retry_find:
1376 page = find_get_page(mapping, pgoff);
1377 if (!page) {
1378 unsigned long ra_pages;
1379
1380 if (VM_SequentialReadHint(area)) {
1381 handle_ra_miss(mapping, ra, pgoff);
1382 goto no_cached_page;
1383 }
1384 ra->mmap_miss++;
1385
1386 /*
1387 * Do we miss much more than hit in this file? If so,
1388 * stop bothering with read-ahead. It will only hurt.
1389 */
1390 if (ra->mmap_miss > ra->mmap_hit + MMAP_LOTSAMISS)
1391 goto no_cached_page;
1392
1393 /*
1394 * To keep the pgmajfault counter straight, we need to
1395 * check did_readaround, as this is an inner loop.
1396 */
1397 if (!did_readaround) {
1398 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001399 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 }
1401 did_readaround = 1;
1402 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1403 if (ra_pages) {
1404 pgoff_t start = 0;
1405
1406 if (pgoff > ra_pages / 2)
1407 start = pgoff - ra_pages / 2;
1408 do_page_cache_readahead(mapping, file, start, ra_pages);
1409 }
1410 page = find_get_page(mapping, pgoff);
1411 if (!page)
1412 goto no_cached_page;
1413 }
1414
1415 if (!did_readaround)
1416 ra->mmap_hit++;
1417
1418 /*
1419 * Ok, found a page in the page cache, now we need to check
1420 * that it's up-to-date.
1421 */
1422 if (!PageUptodate(page))
1423 goto page_not_uptodate;
1424
1425success:
1426 /*
1427 * Found the page and have a reference on it.
1428 */
1429 mark_page_accessed(page);
1430 if (type)
1431 *type = majmin;
1432 return page;
1433
1434outside_data_content:
1435 /*
1436 * An external ptracer can access pages that normally aren't
1437 * accessible..
1438 */
1439 if (area->vm_mm == current->mm)
Adam Litke79f5acf2006-09-29 01:58:43 -07001440 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 /* Fall through to the non-read-ahead case */
1442no_cached_page:
1443 /*
1444 * We're only likely to ever get here if MADV_RANDOM is in
1445 * effect.
1446 */
1447 error = page_cache_read(file, pgoff);
1448 grab_swap_token();
1449
1450 /*
1451 * The page we want has now been added to the page cache.
1452 * In the unlikely event that someone removed it in the
1453 * meantime, we'll just come back here and read it again.
1454 */
1455 if (error >= 0)
1456 goto retry_find;
1457
1458 /*
1459 * An error return from page_cache_read can result if the
1460 * system is low on memory, or a problem occurs while trying
1461 * to schedule I/O.
1462 */
1463 if (error == -ENOMEM)
1464 return NOPAGE_OOM;
Adam Litke79f5acf2006-09-29 01:58:43 -07001465 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466
1467page_not_uptodate:
1468 if (!did_readaround) {
1469 majmin = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001470 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 }
1472 lock_page(page);
1473
1474 /* Did it get unhashed while we waited for it? */
1475 if (!page->mapping) {
1476 unlock_page(page);
1477 page_cache_release(page);
1478 goto retry_all;
1479 }
1480
1481 /* Did somebody else get it up-to-date? */
1482 if (PageUptodate(page)) {
1483 unlock_page(page);
1484 goto success;
1485 }
1486
Zach Brown994fc28c2005-12-15 14:28:17 -08001487 error = mapping->a_ops->readpage(file, page);
1488 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489 wait_on_page_locked(page);
1490 if (PageUptodate(page))
1491 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001492 } else if (error == AOP_TRUNCATED_PAGE) {
1493 page_cache_release(page);
1494 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 }
1496
1497 /*
1498 * Umm, take care of errors if the page isn't up-to-date.
1499 * Try to re-read it _once_. We do this synchronously,
1500 * because there really aren't any performance issues here
1501 * and we need to check for errors.
1502 */
1503 lock_page(page);
1504
1505 /* Somebody truncated the page on us? */
1506 if (!page->mapping) {
1507 unlock_page(page);
1508 page_cache_release(page);
1509 goto retry_all;
1510 }
1511
1512 /* Somebody else successfully read it in? */
1513 if (PageUptodate(page)) {
1514 unlock_page(page);
1515 goto success;
1516 }
1517 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001518 error = mapping->a_ops->readpage(file, page);
1519 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001520 wait_on_page_locked(page);
1521 if (PageUptodate(page))
1522 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001523 } else if (error == AOP_TRUNCATED_PAGE) {
1524 page_cache_release(page);
1525 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 }
1527
1528 /*
1529 * Things didn't work out. Return zero to tell the
1530 * mm layer so, possibly freeing the page cache page first.
1531 */
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001532 shrink_readahead_size_eio(file, ra);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 page_cache_release(page);
Adam Litke79f5acf2006-09-29 01:58:43 -07001534 return NOPAGE_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536EXPORT_SYMBOL(filemap_nopage);
1537
1538static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
1539 int nonblock)
1540{
1541 struct address_space *mapping = file->f_mapping;
1542 struct page *page;
1543 int error;
1544
1545 /*
1546 * Do we have something in the page cache already?
1547 */
1548retry_find:
1549 page = find_get_page(mapping, pgoff);
1550 if (!page) {
1551 if (nonblock)
1552 return NULL;
1553 goto no_cached_page;
1554 }
1555
1556 /*
1557 * Ok, found a page in the page cache, now we need to check
1558 * that it's up-to-date.
1559 */
Jeff Moyerd3457342005-04-16 15:24:05 -07001560 if (!PageUptodate(page)) {
1561 if (nonblock) {
1562 page_cache_release(page);
1563 return NULL;
1564 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 goto page_not_uptodate;
Jeff Moyerd3457342005-04-16 15:24:05 -07001566 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567
1568success:
1569 /*
1570 * Found the page and have a reference on it.
1571 */
1572 mark_page_accessed(page);
1573 return page;
1574
1575no_cached_page:
1576 error = page_cache_read(file, pgoff);
1577
1578 /*
1579 * The page we want has now been added to the page cache.
1580 * In the unlikely event that someone removed it in the
1581 * meantime, we'll just come back here and read it again.
1582 */
1583 if (error >= 0)
1584 goto retry_find;
1585
1586 /*
1587 * An error return from page_cache_read can result if the
1588 * system is low on memory, or a problem occurs while trying
1589 * to schedule I/O.
1590 */
1591 return NULL;
1592
1593page_not_uptodate:
1594 lock_page(page);
1595
Nick Pigginda6052f2006-09-25 23:31:35 -07001596 /* Did it get truncated while we waited for it? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597 if (!page->mapping) {
1598 unlock_page(page);
1599 goto err;
1600 }
1601
1602 /* Did somebody else get it up-to-date? */
1603 if (PageUptodate(page)) {
1604 unlock_page(page);
1605 goto success;
1606 }
1607
Zach Brown994fc28c2005-12-15 14:28:17 -08001608 error = mapping->a_ops->readpage(file, page);
1609 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610 wait_on_page_locked(page);
1611 if (PageUptodate(page))
1612 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001613 } else if (error == AOP_TRUNCATED_PAGE) {
1614 page_cache_release(page);
1615 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 }
1617
1618 /*
1619 * Umm, take care of errors if the page isn't up-to-date.
1620 * Try to re-read it _once_. We do this synchronously,
1621 * because there really aren't any performance issues here
1622 * and we need to check for errors.
1623 */
1624 lock_page(page);
1625
1626 /* Somebody truncated the page on us? */
1627 if (!page->mapping) {
1628 unlock_page(page);
1629 goto err;
1630 }
1631 /* Somebody else successfully read it in? */
1632 if (PageUptodate(page)) {
1633 unlock_page(page);
1634 goto success;
1635 }
1636
1637 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001638 error = mapping->a_ops->readpage(file, page);
1639 if (!error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640 wait_on_page_locked(page);
1641 if (PageUptodate(page))
1642 goto success;
Zach Brown994fc28c2005-12-15 14:28:17 -08001643 } else if (error == AOP_TRUNCATED_PAGE) {
1644 page_cache_release(page);
1645 goto retry_find;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 }
1647
1648 /*
1649 * Things didn't work out. Return zero to tell the
1650 * mm layer so, possibly freeing the page cache page first.
1651 */
1652err:
1653 page_cache_release(page);
1654
1655 return NULL;
1656}
1657
1658int filemap_populate(struct vm_area_struct *vma, unsigned long addr,
1659 unsigned long len, pgprot_t prot, unsigned long pgoff,
1660 int nonblock)
1661{
1662 struct file *file = vma->vm_file;
1663 struct address_space *mapping = file->f_mapping;
1664 struct inode *inode = mapping->host;
1665 unsigned long size;
1666 struct mm_struct *mm = vma->vm_mm;
1667 struct page *page;
1668 int err;
1669
1670 if (!nonblock)
1671 force_page_cache_readahead(mapping, vma->vm_file,
1672 pgoff, len >> PAGE_CACHE_SHIFT);
1673
1674repeat:
1675 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1676 if (pgoff + (len >> PAGE_CACHE_SHIFT) > size)
1677 return -EINVAL;
1678
1679 page = filemap_getpage(file, pgoff, nonblock);
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001680
1681 /* XXX: This is wrong, a filesystem I/O error may have happened. Fix that as
1682 * done in shmem_populate calling shmem_getpage */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 if (!page && !nonblock)
1684 return -ENOMEM;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001685
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 if (page) {
1687 err = install_page(mm, vma, addr, page, prot);
1688 if (err) {
1689 page_cache_release(page);
1690 return err;
1691 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001692 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001693 /* No page was found just because we can't read it in now (being
1694 * here implies nonblock != 0), but the page may exist, so set
1695 * the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 err = install_file_pte(mm, vma, addr, pgoff, prot);
1697 if (err)
1698 return err;
1699 }
1700
1701 len -= PAGE_SIZE;
1702 addr += PAGE_SIZE;
1703 pgoff++;
1704 if (len)
1705 goto repeat;
1706
1707 return 0;
1708}
Nikita Danilovb1459462005-10-29 18:17:02 -07001709EXPORT_SYMBOL(filemap_populate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710
1711struct vm_operations_struct generic_file_vm_ops = {
1712 .nopage = filemap_nopage,
1713 .populate = filemap_populate,
1714};
1715
1716/* This is used for a general mmap of a disk file */
1717
1718int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1719{
1720 struct address_space *mapping = file->f_mapping;
1721
1722 if (!mapping->a_ops->readpage)
1723 return -ENOEXEC;
1724 file_accessed(file);
1725 vma->vm_ops = &generic_file_vm_ops;
1726 return 0;
1727}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728
1729/*
1730 * This is for filesystems which do not implement ->writepage.
1731 */
1732int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1733{
1734 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1735 return -EINVAL;
1736 return generic_file_mmap(file, vma);
1737}
1738#else
1739int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1740{
1741 return -ENOSYS;
1742}
1743int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1744{
1745 return -ENOSYS;
1746}
1747#endif /* CONFIG_MMU */
1748
1749EXPORT_SYMBOL(generic_file_mmap);
1750EXPORT_SYMBOL(generic_file_readonly_mmap);
1751
1752static inline struct page *__read_cache_page(struct address_space *mapping,
1753 unsigned long index,
1754 int (*filler)(void *,struct page*),
1755 void *data)
1756{
1757 struct page *page, *cached_page = NULL;
1758 int err;
1759repeat:
1760 page = find_get_page(mapping, index);
1761 if (!page) {
1762 if (!cached_page) {
1763 cached_page = page_cache_alloc_cold(mapping);
1764 if (!cached_page)
1765 return ERR_PTR(-ENOMEM);
1766 }
1767 err = add_to_page_cache_lru(cached_page, mapping,
1768 index, GFP_KERNEL);
1769 if (err == -EEXIST)
1770 goto repeat;
1771 if (err < 0) {
1772 /* Presumably ENOMEM for radix tree node */
1773 page_cache_release(cached_page);
1774 return ERR_PTR(err);
1775 }
1776 page = cached_page;
1777 cached_page = NULL;
1778 err = filler(data, page);
1779 if (err < 0) {
1780 page_cache_release(page);
1781 page = ERR_PTR(err);
1782 }
1783 }
1784 if (cached_page)
1785 page_cache_release(cached_page);
1786 return page;
1787}
1788
Randy Dunlap485bb992006-06-23 02:03:49 -07001789/**
1790 * read_cache_page - read into page cache, fill it if needed
1791 * @mapping: the page's address_space
1792 * @index: the page index
1793 * @filler: function to perform the read
1794 * @data: destination for read data
1795 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 * Read into the page cache. If a page already exists,
1797 * and PageUptodate() is not set, try to fill the page.
1798 */
1799struct page *read_cache_page(struct address_space *mapping,
1800 unsigned long index,
1801 int (*filler)(void *,struct page*),
1802 void *data)
1803{
1804 struct page *page;
1805 int err;
1806
1807retry:
1808 page = __read_cache_page(mapping, index, filler, data);
1809 if (IS_ERR(page))
1810 goto out;
1811 mark_page_accessed(page);
1812 if (PageUptodate(page))
1813 goto out;
1814
1815 lock_page(page);
1816 if (!page->mapping) {
1817 unlock_page(page);
1818 page_cache_release(page);
1819 goto retry;
1820 }
1821 if (PageUptodate(page)) {
1822 unlock_page(page);
1823 goto out;
1824 }
1825 err = filler(data, page);
1826 if (err < 0) {
1827 page_cache_release(page);
1828 page = ERR_PTR(err);
1829 }
1830 out:
1831 return page;
1832}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833EXPORT_SYMBOL(read_cache_page);
1834
1835/*
1836 * If the page was newly created, increment its refcount and add it to the
1837 * caller's lru-buffering pagevec. This function is specifically for
1838 * generic_file_write().
1839 */
1840static inline struct page *
1841__grab_cache_page(struct address_space *mapping, unsigned long index,
1842 struct page **cached_page, struct pagevec *lru_pvec)
1843{
1844 int err;
1845 struct page *page;
1846repeat:
1847 page = find_lock_page(mapping, index);
1848 if (!page) {
1849 if (!*cached_page) {
1850 *cached_page = page_cache_alloc(mapping);
1851 if (!*cached_page)
1852 return NULL;
1853 }
1854 err = add_to_page_cache(*cached_page, mapping,
1855 index, GFP_KERNEL);
1856 if (err == -EEXIST)
1857 goto repeat;
1858 if (err == 0) {
1859 page = *cached_page;
1860 page_cache_get(page);
1861 if (!pagevec_add(lru_pvec, page))
1862 __pagevec_lru_add(lru_pvec);
1863 *cached_page = NULL;
1864 }
1865 }
1866 return page;
1867}
1868
1869/*
1870 * The logic we want is
1871 *
1872 * if suid or (sgid and xgrp)
1873 * remove privs
1874 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001875int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876{
1877 mode_t mode = dentry->d_inode->i_mode;
1878 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001879
1880 /* suid always must be killed */
1881 if (unlikely(mode & S_ISUID))
1882 kill = ATTR_KILL_SUID;
1883
1884 /*
1885 * sgid without any exec bits is just a mandatory locking mark; leave
1886 * it alone. If some exec bits are set, it's a real sgid; kill it.
1887 */
1888 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1889 kill |= ATTR_KILL_SGID;
1890
Jens Axboe01de85e2006-10-17 19:50:36 +02001891 if (unlikely(kill && !capable(CAP_FSETID)))
1892 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
Jens Axboe01de85e2006-10-17 19:50:36 +02001894 return 0;
1895}
1896
1897int __remove_suid(struct dentry *dentry, int kill)
1898{
1899 struct iattr newattrs;
1900
1901 newattrs.ia_valid = ATTR_FORCE | kill;
1902 return notify_change(dentry, &newattrs);
1903}
1904
1905int remove_suid(struct dentry *dentry)
1906{
1907 int kill = should_remove_suid(dentry);
1908
1909 if (unlikely(kill))
1910 return __remove_suid(dentry, kill);
1911
1912 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913}
1914EXPORT_SYMBOL(remove_suid);
1915
Carsten Otteceffc072005-06-23 22:05:25 -07001916size_t
NeilBrown01408c42006-06-25 05:47:58 -07001917__filemap_copy_from_user_iovec_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 const struct iovec *iov, size_t base, size_t bytes)
1919{
1920 size_t copied = 0, left = 0;
1921
1922 while (bytes) {
1923 char __user *buf = iov->iov_base + base;
1924 int copy = min(bytes, iov->iov_len - base);
1925
1926 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001927 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 copied += copy;
1929 bytes -= copy;
1930 vaddr += copy;
1931 iov++;
1932
NeilBrown01408c42006-06-25 05:47:58 -07001933 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 }
1936 return copied - left;
1937}
1938
1939/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940 * Performs necessary checks before doing a write
1941 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001942 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 * Returns appropriate error code that caller should return or
1944 * zero in case that write should be allowed.
1945 */
1946inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1947{
1948 struct inode *inode = file->f_mapping->host;
1949 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1950
1951 if (unlikely(*pos < 0))
1952 return -EINVAL;
1953
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954 if (!isblk) {
1955 /* FIXME: this is for backwards compatibility with 2.4 */
1956 if (file->f_flags & O_APPEND)
1957 *pos = i_size_read(inode);
1958
1959 if (limit != RLIM_INFINITY) {
1960 if (*pos >= limit) {
1961 send_sig(SIGXFSZ, current, 0);
1962 return -EFBIG;
1963 }
1964 if (*count > limit - (typeof(limit))*pos) {
1965 *count = limit - (typeof(limit))*pos;
1966 }
1967 }
1968 }
1969
1970 /*
1971 * LFS rule
1972 */
1973 if (unlikely(*pos + *count > MAX_NON_LFS &&
1974 !(file->f_flags & O_LARGEFILE))) {
1975 if (*pos >= MAX_NON_LFS) {
1976 send_sig(SIGXFSZ, current, 0);
1977 return -EFBIG;
1978 }
1979 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1980 *count = MAX_NON_LFS - (unsigned long)*pos;
1981 }
1982 }
1983
1984 /*
1985 * Are we about to exceed the fs block limit ?
1986 *
1987 * If we have written data it becomes a short write. If we have
1988 * exceeded without writing data we send a signal and return EFBIG.
1989 * Linus frestrict idea will clean these up nicely..
1990 */
1991 if (likely(!isblk)) {
1992 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1993 if (*count || *pos > inode->i_sb->s_maxbytes) {
1994 send_sig(SIGXFSZ, current, 0);
1995 return -EFBIG;
1996 }
1997 /* zero-length writes at ->s_maxbytes are OK */
1998 }
1999
2000 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2001 *count = inode->i_sb->s_maxbytes - *pos;
2002 } else {
David Howells93614012006-09-30 20:45:40 +02002003#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004 loff_t isize;
2005 if (bdev_read_only(I_BDEV(inode)))
2006 return -EPERM;
2007 isize = i_size_read(inode);
2008 if (*pos >= isize) {
2009 if (*count || *pos > isize)
2010 return -ENOSPC;
2011 }
2012
2013 if (*pos + *count > isize)
2014 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002015#else
2016 return -EPERM;
2017#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002018 }
2019 return 0;
2020}
2021EXPORT_SYMBOL(generic_write_checks);
2022
2023ssize_t
2024generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2025 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2026 size_t count, size_t ocount)
2027{
2028 struct file *file = iocb->ki_filp;
2029 struct address_space *mapping = file->f_mapping;
2030 struct inode *inode = mapping->host;
2031 ssize_t written;
2032
2033 if (count != ocount)
2034 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2035
2036 written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2037 if (written > 0) {
2038 loff_t end = pos + written;
2039 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2040 i_size_write(inode, end);
2041 mark_inode_dirty(inode);
2042 }
2043 *ppos = end;
2044 }
2045
2046 /*
2047 * Sync the fs metadata but not the minor inode changes and
2048 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002049 * i_mutex is held, which protects generic_osync_inode() from
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050 * livelocking.
2051 */
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07002052 if (written >= 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2053 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2054 if (err < 0)
2055 written = err;
2056 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 if (written == count && !is_sync_kiocb(iocb))
2058 written = -EIOCBQUEUED;
2059 return written;
2060}
2061EXPORT_SYMBOL(generic_file_direct_write);
2062
2063ssize_t
2064generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2065 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2066 size_t count, ssize_t written)
2067{
2068 struct file *file = iocb->ki_filp;
2069 struct address_space * mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002070 const struct address_space_operations *a_ops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002071 struct inode *inode = mapping->host;
2072 long status = 0;
2073 struct page *page;
2074 struct page *cached_page = NULL;
2075 size_t bytes;
2076 struct pagevec lru_pvec;
2077 const struct iovec *cur_iov = iov; /* current iovec */
2078 size_t iov_base = 0; /* offset in the current iovec */
2079 char __user *buf;
2080
2081 pagevec_init(&lru_pvec, 0);
2082
2083 /*
2084 * handle partial DIO write. Adjust cur_iov if needed.
2085 */
2086 if (likely(nr_segs == 1))
2087 buf = iov->iov_base + written;
2088 else {
2089 filemap_set_next_iovec(&cur_iov, &iov_base, written);
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002090 buf = cur_iov->iov_base + iov_base;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091 }
2092
2093 do {
2094 unsigned long index;
2095 unsigned long offset;
2096 size_t copied;
2097
2098 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
2099 index = pos >> PAGE_CACHE_SHIFT;
2100 bytes = PAGE_CACHE_SIZE - offset;
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002101
2102 /* Limit the size of the copy to the caller's write size */
2103 bytes = min(bytes, count);
2104
2105 /*
2106 * Limit the size of the copy to that of the current segment,
2107 * because fault_in_pages_readable() doesn't know how to walk
2108 * segments.
2109 */
2110 bytes = min(bytes, cur_iov->iov_len - iov_base);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002111
2112 /*
2113 * Bring in the user page that we will copy from _first_.
2114 * Otherwise there's a nasty deadlock on copying from the
2115 * same page as we're writing to, without it being marked
2116 * up-to-date.
2117 */
Vladimir V. Saveliev6527c2b2006-06-27 02:53:57 -07002118 fault_in_pages_readable(buf, bytes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119
2120 page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
2121 if (!page) {
2122 status = -ENOMEM;
2123 break;
2124 }
2125
Andrew Morton81b0c872006-06-29 02:24:26 -07002126 if (unlikely(bytes == 0)) {
2127 status = 0;
2128 copied = 0;
2129 goto zero_length_segment;
2130 }
2131
Linus Torvalds1da177e2005-04-16 15:20:36 -07002132 status = a_ops->prepare_write(file, page, offset, offset+bytes);
2133 if (unlikely(status)) {
2134 loff_t isize = i_size_read(inode);
Zach Brown994fc28c2005-12-15 14:28:17 -08002135
2136 if (status != AOP_TRUNCATED_PAGE)
2137 unlock_page(page);
2138 page_cache_release(page);
2139 if (status == AOP_TRUNCATED_PAGE)
2140 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002141 /*
2142 * prepare_write() may have instantiated a few blocks
2143 * outside i_size. Trim these off again.
2144 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 if (pos + bytes > isize)
2146 vmtruncate(inode, isize);
2147 break;
2148 }
2149 if (likely(nr_segs == 1))
2150 copied = filemap_copy_from_user(page, offset,
2151 buf, bytes);
2152 else
2153 copied = filemap_copy_from_user_iovec(page, offset,
2154 cur_iov, iov_base, bytes);
2155 flush_dcache_page(page);
2156 status = a_ops->commit_write(file, page, offset, offset+bytes);
Zach Brown994fc28c2005-12-15 14:28:17 -08002157 if (status == AOP_TRUNCATED_PAGE) {
2158 page_cache_release(page);
2159 continue;
2160 }
Andrew Morton81b0c872006-06-29 02:24:26 -07002161zero_length_segment:
2162 if (likely(copied >= 0)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 if (!status)
2164 status = copied;
2165
2166 if (status >= 0) {
2167 written += status;
2168 count -= status;
2169 pos += status;
2170 buf += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002171 if (unlikely(nr_segs > 1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002172 filemap_set_next_iovec(&cur_iov,
2173 &iov_base, status);
Badari Pulavartyb0cfbd92005-06-25 14:55:42 -07002174 if (count)
2175 buf = cur_iov->iov_base +
2176 iov_base;
Martin Schwidefskya5117182005-06-06 13:35:54 -07002177 } else {
2178 iov_base += status;
akpm@osdl.orgf021e922005-05-01 08:58:35 -07002179 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180 }
2181 }
2182 if (unlikely(copied != bytes))
2183 if (status >= 0)
2184 status = -EFAULT;
2185 unlock_page(page);
2186 mark_page_accessed(page);
2187 page_cache_release(page);
2188 if (status < 0)
2189 break;
2190 balance_dirty_pages_ratelimited(mapping);
2191 cond_resched();
2192 } while (count);
2193 *ppos = pos;
2194
2195 if (cached_page)
2196 page_cache_release(cached_page);
2197
2198 /*
2199 * For now, when the user asks for O_SYNC, we'll actually give O_DSYNC
2200 */
2201 if (likely(status >= 0)) {
2202 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2203 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2204 status = generic_osync_inode(inode, mapping,
2205 OSYNC_METADATA|OSYNC_DATA);
2206 }
2207 }
2208
2209 /*
2210 * If we get here for O_DIRECT writes then we must have fallen through
2211 * to buffered writes (block instantiation inside i_size). So we sync
2212 * the file data here, to try to honour O_DIRECT expectations.
2213 */
2214 if (unlikely(file->f_flags & O_DIRECT) && written)
2215 status = filemap_write_and_wait(mapping);
2216
2217 pagevec_lru_add(&lru_pvec);
2218 return written ? written : status;
2219}
2220EXPORT_SYMBOL(generic_file_buffered_write);
2221
Adrian Bunk5ce78522005-09-10 00:26:28 -07002222static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2224 unsigned long nr_segs, loff_t *ppos)
2225{
2226 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002227 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002228 size_t ocount; /* original count */
2229 size_t count; /* after file limit checks */
2230 struct inode *inode = mapping->host;
2231 unsigned long seg;
2232 loff_t pos;
2233 ssize_t written;
2234 ssize_t err;
2235
2236 ocount = 0;
2237 for (seg = 0; seg < nr_segs; seg++) {
2238 const struct iovec *iv = &iov[seg];
2239
2240 /*
2241 * If any segment has a negative length, or the cumulative
2242 * length ever wraps negative then return -EINVAL.
2243 */
2244 ocount += iv->iov_len;
2245 if (unlikely((ssize_t)(ocount|iv->iov_len) < 0))
2246 return -EINVAL;
2247 if (access_ok(VERIFY_READ, iv->iov_base, iv->iov_len))
2248 continue;
2249 if (seg == 0)
2250 return -EFAULT;
2251 nr_segs = seg;
2252 ocount -= iv->iov_len; /* This segment is no good */
2253 break;
2254 }
2255
2256 count = ocount;
2257 pos = *ppos;
2258
2259 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2260
2261 /* We can write back this queue in page reclaim */
2262 current->backing_dev_info = mapping->backing_dev_info;
2263 written = 0;
2264
2265 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2266 if (err)
2267 goto out;
2268
2269 if (count == 0)
2270 goto out;
2271
2272 err = remove_suid(file->f_dentry);
2273 if (err)
2274 goto out;
2275
Christoph Hellwig870f4812006-01-09 20:52:01 -08002276 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002277
2278 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2279 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002280 loff_t endbyte;
2281 ssize_t written_buffered;
2282
2283 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2284 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002285 if (written < 0 || written == count)
2286 goto out;
2287 /*
2288 * direct-io write to a hole: fall through to buffered I/O
2289 * for completing the rest of the request.
2290 */
2291 pos += written;
2292 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002293 written_buffered = generic_file_buffered_write(iocb, iov,
2294 nr_segs, pos, ppos, count,
2295 written);
2296 /*
2297 * If generic_file_buffered_write() retuned a synchronous error
2298 * then we want to return the number of bytes which were
2299 * direct-written, or the error code if that was zero. Note
2300 * that this differs from normal direct-io semantics, which
2301 * will return -EFOO even if some bytes were written.
2302 */
2303 if (written_buffered < 0) {
2304 err = written_buffered;
2305 goto out;
2306 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002307
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002308 /*
2309 * We need to ensure that the page cache pages are written to
2310 * disk and invalidated to preserve the expected O_DIRECT
2311 * semantics.
2312 */
2313 endbyte = pos + written_buffered - written - 1;
2314 err = do_sync_file_range(file, pos, endbyte,
2315 SYNC_FILE_RANGE_WAIT_BEFORE|
2316 SYNC_FILE_RANGE_WRITE|
2317 SYNC_FILE_RANGE_WAIT_AFTER);
2318 if (err == 0) {
2319 written = written_buffered;
2320 invalidate_mapping_pages(mapping,
2321 pos >> PAGE_CACHE_SHIFT,
2322 endbyte >> PAGE_CACHE_SHIFT);
2323 } else {
2324 /*
2325 * We don't know how much we wrote, so just return
2326 * the number of bytes which were direct-written
2327 */
2328 }
2329 } else {
2330 written = generic_file_buffered_write(iocb, iov, nr_segs,
2331 pos, ppos, count, written);
2332 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333out:
2334 current->backing_dev_info = NULL;
2335 return written ? written : err;
2336}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002337
Badari Pulavarty027445c2006-09-30 23:28:46 -07002338ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2339 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340{
2341 struct file *file = iocb->ki_filp;
2342 struct address_space *mapping = file->f_mapping;
2343 struct inode *inode = mapping->host;
2344 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345
Badari Pulavarty027445c2006-09-30 23:28:46 -07002346 BUG_ON(iocb->ki_pos != pos);
2347
2348 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2349 &iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350
2351 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Badari Pulavarty027445c2006-09-30 23:28:46 -07002352 ssize_t err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002353
2354 err = sync_page_range_nolock(inode, mapping, pos, ret);
2355 if (err < 0)
2356 ret = err;
2357 }
2358 return ret;
2359}
Badari Pulavarty027445c2006-09-30 23:28:46 -07002360EXPORT_SYMBOL(generic_file_aio_write_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361
Badari Pulavarty027445c2006-09-30 23:28:46 -07002362ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2363 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002364{
2365 struct file *file = iocb->ki_filp;
2366 struct address_space *mapping = file->f_mapping;
2367 struct inode *inode = mapping->host;
2368 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002369
2370 BUG_ON(iocb->ki_pos != pos);
2371
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002372 mutex_lock(&inode->i_mutex);
Badari Pulavarty027445c2006-09-30 23:28:46 -07002373 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2374 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002375 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376
2377 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2378 ssize_t err;
2379
2380 err = sync_page_range(inode, mapping, pos, ret);
2381 if (err < 0)
2382 ret = err;
2383 }
2384 return ret;
2385}
2386EXPORT_SYMBOL(generic_file_aio_write);
2387
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388/*
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002389 * Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390 * went wrong during pagecache shootdown.
2391 */
Adrian Bunk5ce78522005-09-10 00:26:28 -07002392static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
2394 loff_t offset, unsigned long nr_segs)
2395{
2396 struct file *file = iocb->ki_filp;
2397 struct address_space *mapping = file->f_mapping;
2398 ssize_t retval;
2399 size_t write_len = 0;
2400
2401 /*
2402 * If it's a write, unmap all mmappings of the file up-front. This
2403 * will cause any pte dirty bits to be propagated into the pageframes
2404 * for the subsequent filemap_write_and_wait().
2405 */
2406 if (rw == WRITE) {
2407 write_len = iov_length(iov, nr_segs);
2408 if (mapping_mapped(mapping))
2409 unmap_mapping_range(mapping, offset, write_len, 0);
2410 }
2411
2412 retval = filemap_write_and_wait(mapping);
2413 if (retval == 0) {
2414 retval = mapping->a_ops->direct_IO(rw, iocb, iov,
2415 offset, nr_segs);
2416 if (rw == WRITE && mapping->nrpages) {
2417 pgoff_t end = (offset + write_len - 1)
2418 >> PAGE_CACHE_SHIFT;
2419 int err = invalidate_inode_pages2_range(mapping,
2420 offset >> PAGE_CACHE_SHIFT, end);
2421 if (err)
2422 retval = err;
2423 }
2424 }
2425 return retval;
2426}
David Howellscf9a2ae2006-08-29 19:05:54 +01002427
2428/**
2429 * try_to_release_page() - release old fs-specific metadata on a page
2430 *
2431 * @page: the page which the kernel is trying to free
2432 * @gfp_mask: memory allocation flags (and I/O mode)
2433 *
2434 * The address_space is to try to release any data against the page
2435 * (presumably at page->private). If the release was successful, return `1'.
2436 * Otherwise return zero.
2437 *
2438 * The @gfp_mask argument specifies whether I/O may be performed to release
2439 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
2440 *
2441 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
2442 */
2443int try_to_release_page(struct page *page, gfp_t gfp_mask)
2444{
2445 struct address_space * const mapping = page->mapping;
2446
2447 BUG_ON(!PageLocked(page));
2448 if (PageWriteback(page))
2449 return 0;
2450
2451 if (mapping && mapping->a_ops->releasepage)
2452 return mapping->a_ops->releasepage(page, gfp_mask);
2453 return try_to_free_buffers(page);
2454}
2455
2456EXPORT_SYMBOL(try_to_release_page);