blob: 876bc595d0f8b3b3e4f626bf1ad7acbb657bdc66 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/filemap.c
3 *
4 * Copyright (C) 1994-1999 Linus Torvalds
5 */
6
7/*
8 * This file handles the generic file mmap semantics used by
9 * most "normal" filesystems (but you don't /have/ to use this:
10 * the NFS filesystem used to do this differently, for example)
11 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/module.h>
13#include <linux/slab.h>
14#include <linux/compiler.h>
15#include <linux/fs.h>
Hiro Yoshiokac22ce142006-06-23 02:04:16 -070016#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017#include <linux/aio.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080018#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/kernel_stat.h>
20#include <linux/mm.h>
21#include <linux/swap.h>
22#include <linux/mman.h>
23#include <linux/pagemap.h>
24#include <linux/file.h>
25#include <linux/uio.h>
26#include <linux/hash.h>
27#include <linux/writeback.h>
Linus Torvalds53253382007-10-18 14:47:32 -070028#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/pagevec.h>
30#include <linux/blkdev.h>
31#include <linux/security.h>
32#include <linux/syscalls.h>
Paul Jackson44110fe2006-03-24 03:16:04 -080033#include <linux/cpuset.h>
Nick Piggin2f718ff2007-10-16 01:24:59 -070034#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080035#include <linux/memcontrol.h>
Nick Piggin0f8053a2006-03-22 00:08:33 -080036#include "internal.h"
37
Linus Torvalds1da177e2005-04-16 15:20:36 -070038/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 * FIXME: remove all knowledge of the buffer layer from the core VM
40 */
41#include <linux/buffer_head.h> /* for generic_osync_inode */
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043#include <asm/mman.h>
44
Adrian Bunk5ce78522005-09-10 00:26:28 -070045
Linus Torvalds1da177e2005-04-16 15:20:36 -070046/*
47 * Shared mappings implemented 30.11.1994. It's not fully working yet,
48 * though.
49 *
50 * Shared mappings now work. 15.8.1995 Bruno.
51 *
52 * finished 'unifying' the page and buffer cache and SMP-threaded the
53 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
54 *
55 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
56 */
57
58/*
59 * Lock ordering:
60 *
61 * ->i_mmap_lock (vmtruncate)
62 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070063 * ->swap_lock (exclusive_swap_page, others)
64 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080066 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 * ->i_mmap_lock (truncate->unmap_mapping_range)
68 *
69 * ->mmap_sem
70 * ->i_mmap_lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070071 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
73 *
74 * ->mmap_sem
75 * ->lock_page (access_process_vm)
76 *
Nick Piggin82591e62006-10-19 23:29:10 -070077 * ->i_mutex (generic_file_buffered_write)
78 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080080 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 * ->i_alloc_sem (various)
82 *
83 * ->inode_lock
84 * ->sb_lock (fs/fs-writeback.c)
85 * ->mapping->tree_lock (__sync_single_inode)
86 *
87 * ->i_mmap_lock
88 * ->anon_vma.lock (vma_adjust)
89 *
90 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070091 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070093 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070094 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 * ->private_lock (try_to_unmap_one)
96 * ->tree_lock (try_to_unmap_one)
97 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -080098 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 * ->private_lock (page_remove_rmap->set_page_dirty)
100 * ->tree_lock (page_remove_rmap->set_page_dirty)
101 * ->inode_lock (page_remove_rmap->set_page_dirty)
102 * ->inode_lock (zap_pte_range->set_page_dirty)
103 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
104 *
105 * ->task->proc_lock
106 * ->dcache_lock (proc_pid_lookup)
107 */
108
109/*
110 * Remove a page from the page cache and free it. Caller has to make
111 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700112 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 */
114void __remove_from_page_cache(struct page *page)
115{
116 struct address_space *mapping = page->mapping;
117
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700118 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 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);
Nick Piggin45426812007-07-15 23:38:12 -0700123 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800124
125 /*
126 * Some filesystems seem to re-dirty the page even after
127 * the VM has canceled the dirty bit (eg ext3 journaling).
128 *
129 * Fix it up by doing a final dirty accounting check after
130 * having removed the page entirely.
131 */
132 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
133 dec_zone_page_state(page, NR_FILE_DIRTY);
134 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
135 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136}
137
138void remove_from_page_cache(struct page *page)
139{
140 struct address_space *mapping = page->mapping;
141
Matt Mackallcd7619d2005-05-01 08:59:01 -0700142 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Nick Piggin19fd6232008-07-25 19:45:32 -0700144 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700146 spin_unlock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147}
148
149static int sync_page(void *word)
150{
151 struct address_space *mapping;
152 struct page *page;
153
Andi Kleen07808b72005-11-05 17:25:53 +0100154 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155
156 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700157 * page_mapping() is being called without PG_locked held.
158 * Some knowledge of the state and use of the page is used to
159 * reduce the requirements down to a memory barrier.
160 * The danger here is of a stale page_mapping() return value
161 * indicating a struct address_space different from the one it's
162 * associated with when it is associated with one.
163 * After smp_mb(), it's either the correct page_mapping() for
164 * the page, or an old page_mapping() and the page's own
165 * page_mapping() has gone NULL.
166 * The ->sync_page() address_space operation must tolerate
167 * page_mapping() going NULL. By an amazing coincidence,
168 * this comes about because none of the users of the page
169 * in the ->sync_page() methods make essential use of the
170 * page_mapping(), merely passing the page down to the backing
171 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700172 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700173 * of interest. When page_mapping() does go NULL, the entire
174 * call stack gracefully ignores the page and returns.
175 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 */
177 smp_mb();
178 mapping = page_mapping(page);
179 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
180 mapping->a_ops->sync_page(page);
181 io_schedule();
182 return 0;
183}
184
Matthew Wilcox2687a352007-12-06 11:18:49 -0500185static int sync_page_killable(void *word)
186{
187 sync_page(word);
188 return fatal_signal_pending(current) ? -EINTR : 0;
189}
190
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700192 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700193 * @mapping: address space structure to write
194 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800195 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700196 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700198 * Start writeback against all of a mapping's dirty pages that lie
199 * within the byte offsets <start, end> inclusive.
200 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700202 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 * these two operations is that if a dirty page/buffer is encountered, it must
204 * be waited upon, and not just skipped over.
205 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800206int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
207 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208{
209 int ret;
210 struct writeback_control wbc = {
211 .sync_mode = sync_mode,
212 .nr_to_write = mapping->nrpages * 2,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700213 .range_start = start,
214 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 };
216
217 if (!mapping_cap_writeback_dirty(mapping))
218 return 0;
219
220 ret = do_writepages(mapping, &wbc);
221 return ret;
222}
223
224static inline int __filemap_fdatawrite(struct address_space *mapping,
225 int sync_mode)
226{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700227 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228}
229
230int filemap_fdatawrite(struct address_space *mapping)
231{
232 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
233}
234EXPORT_SYMBOL(filemap_fdatawrite);
235
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400236int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800237 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238{
239 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
240}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400241EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242
Randy Dunlap485bb992006-06-23 02:03:49 -0700243/**
244 * filemap_flush - mostly a non-blocking flush
245 * @mapping: target address_space
246 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 * This is a mostly non-blocking flush. Not suitable for data-integrity
248 * purposes - I/O may not be started against all dirty pages.
249 */
250int filemap_flush(struct address_space *mapping)
251{
252 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
253}
254EXPORT_SYMBOL(filemap_flush);
255
Randy Dunlap485bb992006-06-23 02:03:49 -0700256/**
257 * wait_on_page_writeback_range - wait for writeback to complete
258 * @mapping: target address_space
259 * @start: beginning page index
260 * @end: ending page index
261 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 * Wait for writeback to complete against pages indexed by start->end
263 * inclusive
264 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800265int wait_on_page_writeback_range(struct address_space *mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 pgoff_t start, pgoff_t end)
267{
268 struct pagevec pvec;
269 int nr_pages;
270 int ret = 0;
271 pgoff_t index;
272
273 if (end < start)
274 return 0;
275
276 pagevec_init(&pvec, 0);
277 index = start;
278 while ((index <= end) &&
279 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
280 PAGECACHE_TAG_WRITEBACK,
281 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
282 unsigned i;
283
284 for (i = 0; i < nr_pages; i++) {
285 struct page *page = pvec.pages[i];
286
287 /* until radix tree lookup accepts end_index */
288 if (page->index > end)
289 continue;
290
291 wait_on_page_writeback(page);
292 if (PageError(page))
293 ret = -EIO;
294 }
295 pagevec_release(&pvec);
296 cond_resched();
297 }
298
299 /* Check for outstanding write errors */
300 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
301 ret = -ENOSPC;
302 if (test_and_clear_bit(AS_EIO, &mapping->flags))
303 ret = -EIO;
304
305 return ret;
306}
307
Randy Dunlap485bb992006-06-23 02:03:49 -0700308/**
309 * sync_page_range - write and wait on all pages in the passed range
310 * @inode: target inode
311 * @mapping: target address_space
312 * @pos: beginning offset in pages to write
313 * @count: number of bytes to write
314 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 * Write and wait upon all the pages in the passed range. This is a "data
316 * integrity" operation. It waits upon in-flight writeout before starting and
317 * waiting upon new writeout. If there was an IO error, return it.
318 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800319 * We need to re-take i_mutex during the generic_osync_inode list walk because
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 * it is otherwise livelockable.
321 */
322int sync_page_range(struct inode *inode, struct address_space *mapping,
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800323 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324{
325 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
326 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
327 int ret;
328
329 if (!mapping_cap_writeback_dirty(mapping) || !count)
330 return 0;
331 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
332 if (ret == 0) {
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800333 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800335 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 }
337 if (ret == 0)
338 ret = wait_on_page_writeback_range(mapping, start, end);
339 return ret;
340}
341EXPORT_SYMBOL(sync_page_range);
342
Randy Dunlap485bb992006-06-23 02:03:49 -0700343/**
Randy Dunlap76824862008-03-19 17:00:40 -0700344 * sync_page_range_nolock - write & wait on all pages in the passed range without locking
Randy Dunlap485bb992006-06-23 02:03:49 -0700345 * @inode: target inode
346 * @mapping: target address_space
347 * @pos: beginning offset in pages to write
348 * @count: number of bytes to write
349 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800350 * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 * as it forces O_SYNC writers to different parts of the same file
352 * to be serialised right until io completion.
353 */
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800354int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
355 loff_t pos, loff_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356{
357 pgoff_t start = pos >> PAGE_CACHE_SHIFT;
358 pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
359 int ret;
360
361 if (!mapping_cap_writeback_dirty(mapping) || !count)
362 return 0;
363 ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
364 if (ret == 0)
365 ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
366 if (ret == 0)
367 ret = wait_on_page_writeback_range(mapping, start, end);
368 return ret;
369}
OGAWA Hirofumi268fc162006-01-08 01:02:12 -0800370EXPORT_SYMBOL(sync_page_range_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371
372/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700373 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700375 *
376 * Walk the list of under-writeback pages of the given address space
377 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 */
379int filemap_fdatawait(struct address_space *mapping)
380{
381 loff_t i_size = i_size_read(mapping->host);
382
383 if (i_size == 0)
384 return 0;
385
386 return wait_on_page_writeback_range(mapping, 0,
387 (i_size - 1) >> PAGE_CACHE_SHIFT);
388}
389EXPORT_SYMBOL(filemap_fdatawait);
390
391int filemap_write_and_wait(struct address_space *mapping)
392{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800393 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394
395 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800396 err = filemap_fdatawrite(mapping);
397 /*
398 * Even if the above returned error, the pages may be
399 * written partially (e.g. -ENOSPC), so we wait for it.
400 * But the -EIO is special case, it may indicate the worst
401 * thing (e.g. bug) happened, so we avoid waiting for it.
402 */
403 if (err != -EIO) {
404 int err2 = filemap_fdatawait(mapping);
405 if (!err)
406 err = err2;
407 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800409 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800411EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412
Randy Dunlap485bb992006-06-23 02:03:49 -0700413/**
414 * filemap_write_and_wait_range - write out & wait on a file range
415 * @mapping: the address_space for the pages
416 * @lstart: offset in bytes where the range starts
417 * @lend: offset in bytes where the range ends (inclusive)
418 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800419 * Write out and wait upon file offsets lstart->lend, inclusive.
420 *
421 * Note that `lend' is inclusive (describes the last byte to be written) so
422 * that this function can be used to write to the very end-of-file (end = -1).
423 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424int filemap_write_and_wait_range(struct address_space *mapping,
425 loff_t lstart, loff_t lend)
426{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800427 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428
429 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800430 err = __filemap_fdatawrite_range(mapping, lstart, lend,
431 WB_SYNC_ALL);
432 /* See comment of filemap_write_and_wait() */
433 if (err != -EIO) {
434 int err2 = wait_on_page_writeback_range(mapping,
435 lstart >> PAGE_CACHE_SHIFT,
436 lend >> PAGE_CACHE_SHIFT);
437 if (!err)
438 err = err2;
439 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800441 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442}
443
Randy Dunlap485bb992006-06-23 02:03:49 -0700444/**
Nick Piggine2867812008-07-25 19:45:30 -0700445 * add_to_page_cache_locked - add a locked page to the pagecache
Randy Dunlap485bb992006-06-23 02:03:49 -0700446 * @page: page to add
447 * @mapping: the page's address_space
448 * @offset: page index
449 * @gfp_mask: page allocation mode
450 *
Nick Piggine2867812008-07-25 19:45:30 -0700451 * This function is used to add a page to the pagecache. It must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 * This function does not add the page to the LRU. The caller must do that.
453 */
Nick Piggine2867812008-07-25 19:45:30 -0700454int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400455 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456{
Nick Piggine2867812008-07-25 19:45:30 -0700457 int error;
458
459 VM_BUG_ON(!PageLocked(page));
460
461 error = mem_cgroup_cache_charge(page, current->mm,
Badari Pulavarty4c6bc8d2008-02-07 00:14:05 -0800462 gfp_mask & ~__GFP_HIGHMEM);
Balbir Singh35c754d2008-02-07 00:14:05 -0800463 if (error)
464 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465
Balbir Singh35c754d2008-02-07 00:14:05 -0800466 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 if (error == 0) {
Nick Piggine2867812008-07-25 19:45:30 -0700468 page_cache_get(page);
469 page->mapping = mapping;
470 page->index = offset;
471
Nick Piggin19fd6232008-07-25 19:45:32 -0700472 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 error = radix_tree_insert(&mapping->page_tree, offset, page);
Nick Piggine2867812008-07-25 19:45:30 -0700474 if (likely(!error)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700476 __inc_zone_page_state(page, NR_FILE_PAGES);
Nick Piggine2867812008-07-25 19:45:30 -0700477 } else {
478 page->mapping = NULL;
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700479 mem_cgroup_uncharge_cache_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700480 page_cache_release(page);
481 }
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800482
Nick Piggin19fd6232008-07-25 19:45:32 -0700483 spin_unlock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800485 } else
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700486 mem_cgroup_uncharge_cache_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800487out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 return error;
489}
Nick Piggine2867812008-07-25 19:45:30 -0700490EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491
492int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400493 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700494{
495 int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
496 if (ret == 0)
497 lru_cache_add(page);
498 return ret;
499}
500
Paul Jackson44110fe2006-03-24 03:16:04 -0800501#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700502struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800503{
504 if (cpuset_do_page_mem_spread()) {
505 int n = cpuset_mem_spread_node();
Nick Piggin2ae88142006-10-28 10:38:23 -0700506 return alloc_pages_node(n, gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800507 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700508 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800509}
Nick Piggin2ae88142006-10-28 10:38:23 -0700510EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800511#endif
512
Nick Piggindb376482006-09-25 23:31:24 -0700513static int __sleep_on_page_lock(void *word)
514{
515 io_schedule();
516 return 0;
517}
518
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519/*
520 * In order to wait for pages to become available there must be
521 * waitqueues associated with pages. By using a hash table of
522 * waitqueues where the bucket discipline is to maintain all
523 * waiters on the same queue and wake all when any of the pages
524 * become available, and for the woken contexts to check to be
525 * sure the appropriate page became available, this saves space
526 * at a cost of "thundering herd" phenomena during rare hash
527 * collisions.
528 */
529static wait_queue_head_t *page_waitqueue(struct page *page)
530{
531 const struct zone *zone = page_zone(page);
532
533 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
534}
535
536static inline void wake_up_page(struct page *page, int bit)
537{
538 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
539}
540
Harvey Harrison920c7a52008-02-04 22:29:26 -0800541void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542{
543 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
544
545 if (test_bit(bit_nr, &page->flags))
546 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
547 TASK_UNINTERRUPTIBLE);
548}
549EXPORT_SYMBOL(wait_on_page_bit);
550
551/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700552 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 * @page: the page
554 *
555 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
556 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
557 * mechananism between PageLocked pages and PageWriteback pages is shared.
558 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
559 *
560 * The first mb is necessary to safely close the critical section opened by the
Nick Piggin529ae9a2008-08-02 12:01:03 +0200561 * test_and_set_bit() to lock the page; the second mb is necessary to enforce
562 * ordering between the clear_bit and the read of the waitqueue (to avoid SMP
563 * races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800565void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566{
567 smp_mb__before_clear_bit();
Nick Piggin529ae9a2008-08-02 12:01:03 +0200568 if (!test_and_clear_bit(PG_locked, &page->flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 BUG();
570 smp_mb__after_clear_bit();
571 wake_up_page(page, PG_locked);
572}
573EXPORT_SYMBOL(unlock_page);
574
Randy Dunlap485bb992006-06-23 02:03:49 -0700575/**
576 * end_page_writeback - end writeback against a page
577 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 */
579void end_page_writeback(struct page *page)
580{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700581 if (TestClearPageReclaim(page))
582 rotate_reclaimable_page(page);
583
584 if (!test_clear_page_writeback(page))
585 BUG();
586
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 smp_mb__after_clear_bit();
588 wake_up_page(page, PG_writeback);
589}
590EXPORT_SYMBOL(end_page_writeback);
591
Randy Dunlap485bb992006-06-23 02:03:49 -0700592/**
593 * __lock_page - get a lock on the page, assuming we need to sleep to get it
594 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700596 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
598 * chances are that on the second loop, the block layer's plug list is empty,
599 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
600 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800601void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602{
603 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
604
605 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
606 TASK_UNINTERRUPTIBLE);
607}
608EXPORT_SYMBOL(__lock_page);
609
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800610int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500611{
612 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
613
614 return __wait_on_bit_lock(page_waitqueue(page), &wait,
615 sync_page_killable, TASK_KILLABLE);
616}
617
Randy Dunlap76824862008-03-19 17:00:40 -0700618/**
619 * __lock_page_nosync - get a lock on the page, without calling sync_page()
620 * @page: the page to lock
621 *
Nick Piggindb376482006-09-25 23:31:24 -0700622 * Variant of lock_page that does not require the caller to hold a reference
623 * on the page's mapping.
624 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800625void __lock_page_nosync(struct page *page)
Nick Piggindb376482006-09-25 23:31:24 -0700626{
627 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
628 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
629 TASK_UNINTERRUPTIBLE);
630}
631
Randy Dunlap485bb992006-06-23 02:03:49 -0700632/**
633 * find_get_page - find and get a page reference
634 * @mapping: the address_space to search
635 * @offset: the page index
636 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700637 * Is there a pagecache struct page at the given (mapping, offset) tuple?
638 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 */
Nick Piggina60637c2008-07-25 19:45:31 -0700640struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641{
Nick Piggina60637c2008-07-25 19:45:31 -0700642 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 struct page *page;
644
Nick Piggina60637c2008-07-25 19:45:31 -0700645 rcu_read_lock();
646repeat:
647 page = NULL;
648 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
649 if (pagep) {
650 page = radix_tree_deref_slot(pagep);
651 if (unlikely(!page || page == RADIX_TREE_RETRY))
652 goto repeat;
653
654 if (!page_cache_get_speculative(page))
655 goto repeat;
656
657 /*
658 * Has the page moved?
659 * This is part of the lockless pagecache protocol. See
660 * include/linux/pagemap.h for details.
661 */
662 if (unlikely(page != *pagep)) {
663 page_cache_release(page);
664 goto repeat;
665 }
666 }
667 rcu_read_unlock();
668
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 return page;
670}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671EXPORT_SYMBOL(find_get_page);
672
Randy Dunlap485bb992006-06-23 02:03:49 -0700673/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700675 * @mapping: the address_space to search
676 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677 *
678 * Locates the desired pagecache page, locks it, increments its reference
679 * count and returns its address.
680 *
681 * Returns zero if the page was not present. find_lock_page() may sleep.
682 */
Nick Piggina60637c2008-07-25 19:45:31 -0700683struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700684{
685 struct page *page;
686
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687repeat:
Nick Piggina60637c2008-07-25 19:45:31 -0700688 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 if (page) {
Nick Piggina60637c2008-07-25 19:45:31 -0700690 lock_page(page);
691 /* Has the page been truncated? */
692 if (unlikely(page->mapping != mapping)) {
693 unlock_page(page);
694 page_cache_release(page);
695 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 }
Nick Piggina60637c2008-07-25 19:45:31 -0700697 VM_BUG_ON(page->index != offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 return page;
700}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701EXPORT_SYMBOL(find_lock_page);
702
703/**
704 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700705 * @mapping: the page's address_space
706 * @index: the page's index into the mapping
707 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 *
709 * Locates a page in the pagecache. If the page is not present, a new page
710 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
711 * LRU list. The returned page is locked and has its reference count
712 * incremented.
713 *
714 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
715 * allocation!
716 *
717 * find_or_create_page() returns the desired page's address, or zero on
718 * memory exhaustion.
719 */
720struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700721 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722{
Nick Piggineb2be182007-10-16 01:24:57 -0700723 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 int err;
725repeat:
726 page = find_lock_page(mapping, index);
727 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700728 page = __page_cache_alloc(gfp_mask);
729 if (!page)
730 return NULL;
731 err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
732 if (unlikely(err)) {
733 page_cache_release(page);
734 page = NULL;
735 if (err == -EEXIST)
736 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 return page;
740}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741EXPORT_SYMBOL(find_or_create_page);
742
743/**
744 * find_get_pages - gang pagecache lookup
745 * @mapping: The address_space to search
746 * @start: The starting page index
747 * @nr_pages: The maximum number of pages
748 * @pages: Where the resulting pages are placed
749 *
750 * find_get_pages() will search for and return a group of up to
751 * @nr_pages pages in the mapping. The pages are placed at @pages.
752 * find_get_pages() takes a reference against the returned pages.
753 *
754 * The search returns a group of mapping-contiguous pages with ascending
755 * indexes. There may be holes in the indices due to not-present pages.
756 *
757 * find_get_pages() returns the number of pages which were found.
758 */
759unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
760 unsigned int nr_pages, struct page **pages)
761{
762 unsigned int i;
763 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700764 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765
Nick Piggina60637c2008-07-25 19:45:31 -0700766 rcu_read_lock();
767restart:
768 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
769 (void ***)pages, start, nr_pages);
770 ret = 0;
771 for (i = 0; i < nr_found; i++) {
772 struct page *page;
773repeat:
774 page = radix_tree_deref_slot((void **)pages[i]);
775 if (unlikely(!page))
776 continue;
777 /*
778 * this can only trigger if nr_found == 1, making livelock
779 * a non issue.
780 */
781 if (unlikely(page == RADIX_TREE_RETRY))
782 goto restart;
783
784 if (!page_cache_get_speculative(page))
785 goto repeat;
786
787 /* Has the page moved? */
788 if (unlikely(page != *((void **)pages[i]))) {
789 page_cache_release(page);
790 goto repeat;
791 }
792
793 pages[ret] = page;
794 ret++;
795 }
796 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 return ret;
798}
799
Jens Axboeebf43502006-04-27 08:46:01 +0200800/**
801 * find_get_pages_contig - gang contiguous pagecache lookup
802 * @mapping: The address_space to search
803 * @index: The starting page index
804 * @nr_pages: The maximum number of pages
805 * @pages: Where the resulting pages are placed
806 *
807 * find_get_pages_contig() works exactly like find_get_pages(), except
808 * that the returned number of pages are guaranteed to be contiguous.
809 *
810 * find_get_pages_contig() returns the number of pages which were found.
811 */
812unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
813 unsigned int nr_pages, struct page **pages)
814{
815 unsigned int i;
816 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700817 unsigned int nr_found;
Jens Axboeebf43502006-04-27 08:46:01 +0200818
Nick Piggina60637c2008-07-25 19:45:31 -0700819 rcu_read_lock();
820restart:
821 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
822 (void ***)pages, index, nr_pages);
823 ret = 0;
824 for (i = 0; i < nr_found; i++) {
825 struct page *page;
826repeat:
827 page = radix_tree_deref_slot((void **)pages[i]);
828 if (unlikely(!page))
829 continue;
830 /*
831 * this can only trigger if nr_found == 1, making livelock
832 * a non issue.
833 */
834 if (unlikely(page == RADIX_TREE_RETRY))
835 goto restart;
836
837 if (page->mapping == NULL || page->index != index)
Jens Axboeebf43502006-04-27 08:46:01 +0200838 break;
839
Nick Piggina60637c2008-07-25 19:45:31 -0700840 if (!page_cache_get_speculative(page))
841 goto repeat;
842
843 /* Has the page moved? */
844 if (unlikely(page != *((void **)pages[i]))) {
845 page_cache_release(page);
846 goto repeat;
847 }
848
849 pages[ret] = page;
850 ret++;
Jens Axboeebf43502006-04-27 08:46:01 +0200851 index++;
852 }
Nick Piggina60637c2008-07-25 19:45:31 -0700853 rcu_read_unlock();
854 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +0200855}
David Howellsef71c152007-05-09 02:33:44 -0700856EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200857
Randy Dunlap485bb992006-06-23 02:03:49 -0700858/**
859 * find_get_pages_tag - find and return pages that match @tag
860 * @mapping: the address_space to search
861 * @index: the starting page index
862 * @tag: the tag index
863 * @nr_pages: the maximum number of pages
864 * @pages: where the resulting pages are placed
865 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700867 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700868 */
869unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
870 int tag, unsigned int nr_pages, struct page **pages)
871{
872 unsigned int i;
873 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700874 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875
Nick Piggina60637c2008-07-25 19:45:31 -0700876 rcu_read_lock();
877restart:
878 nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
879 (void ***)pages, *index, nr_pages, tag);
880 ret = 0;
881 for (i = 0; i < nr_found; i++) {
882 struct page *page;
883repeat:
884 page = radix_tree_deref_slot((void **)pages[i]);
885 if (unlikely(!page))
886 continue;
887 /*
888 * this can only trigger if nr_found == 1, making livelock
889 * a non issue.
890 */
891 if (unlikely(page == RADIX_TREE_RETRY))
892 goto restart;
893
894 if (!page_cache_get_speculative(page))
895 goto repeat;
896
897 /* Has the page moved? */
898 if (unlikely(page != *((void **)pages[i]))) {
899 page_cache_release(page);
900 goto repeat;
901 }
902
903 pages[ret] = page;
904 ret++;
905 }
906 rcu_read_unlock();
907
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 if (ret)
909 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -0700910
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 return ret;
912}
David Howellsef71c152007-05-09 02:33:44 -0700913EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914
Randy Dunlap485bb992006-06-23 02:03:49 -0700915/**
916 * grab_cache_page_nowait - returns locked page at given index in given cache
917 * @mapping: target address_space
918 * @index: the page index
919 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800920 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 * This is intended for speculative data generators, where the data can
922 * be regenerated if the page couldn't be grabbed. This routine should
923 * be safe to call while holding the lock for another page.
924 *
925 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
926 * and deadlock against the caller's locked page.
927 */
928struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700929grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930{
931 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932
933 if (page) {
Nick Piggin529ae9a2008-08-02 12:01:03 +0200934 if (trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935 return page;
936 page_cache_release(page);
937 return NULL;
938 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700939 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
940 if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 page_cache_release(page);
942 page = NULL;
943 }
944 return page;
945}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700946EXPORT_SYMBOL(grab_cache_page_nowait);
947
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700948/*
949 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
950 * a _large_ part of the i/o request. Imagine the worst scenario:
951 *
952 * ---R__________________________________________B__________
953 * ^ reading here ^ bad block(assume 4k)
954 *
955 * read(R) => miss => readahead(R...B) => media error => frustrating retries
956 * => failing the whole request => read(R) => read(R+1) =>
957 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
958 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
959 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
960 *
961 * It is going insane. Fix it by quickly scaling down the readahead size.
962 */
963static void shrink_readahead_size_eio(struct file *filp,
964 struct file_ra_state *ra)
965{
966 if (!ra->ra_pages)
967 return;
968
969 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700970}
971
Randy Dunlap485bb992006-06-23 02:03:49 -0700972/**
Christoph Hellwig36e78912008-02-08 04:21:24 -0800973 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -0700974 * @filp: the file to read
975 * @ppos: current file position
976 * @desc: read_descriptor
977 * @actor: read method
978 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700980 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 *
982 * This is really ugly. But the goto's actually try to clarify some
983 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 */
Christoph Hellwig36e78912008-02-08 04:21:24 -0800985static void do_generic_file_read(struct file *filp, loff_t *ppos,
986 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987{
Christoph Hellwig36e78912008-02-08 04:21:24 -0800988 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -0800990 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700991 pgoff_t index;
992 pgoff_t last_index;
993 pgoff_t prev_index;
994 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -0700995 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -0700999 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
1000 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
1002 offset = *ppos & ~PAGE_CACHE_MASK;
1003
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 for (;;) {
1005 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001006 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -07001007 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008 unsigned long nr, ret;
1009
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011find_page:
1012 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001013 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001014 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001015 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001016 index, last_index - index);
1017 page = find_get_page(mapping, index);
1018 if (unlikely(page == NULL))
1019 goto no_cached_page;
1020 }
1021 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001022 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001023 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001024 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001026 if (!PageUptodate(page)) {
1027 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1028 !mapping->a_ops->is_partially_uptodate)
1029 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001030 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001031 goto page_not_up_to_date;
1032 if (!mapping->a_ops->is_partially_uptodate(page,
1033 desc, offset))
1034 goto page_not_up_to_date_locked;
1035 unlock_page(page);
1036 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001038 /*
1039 * i_size must be checked after we know the page is Uptodate.
1040 *
1041 * Checking i_size after the check allows us to calculate
1042 * the correct value for "nr", which means the zero-filled
1043 * part of the page is not copied back to userspace (unless
1044 * another truncate extends the file - this is desired though).
1045 */
1046
1047 isize = i_size_read(inode);
1048 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1049 if (unlikely(!isize || index > end_index)) {
1050 page_cache_release(page);
1051 goto out;
1052 }
1053
1054 /* nr is the maximum number of bytes to copy from this page */
1055 nr = PAGE_CACHE_SIZE;
1056 if (index == end_index) {
1057 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1058 if (nr <= offset) {
1059 page_cache_release(page);
1060 goto out;
1061 }
1062 }
1063 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064
1065 /* If users can be writing to this page using arbitrary
1066 * virtual addresses, take care about potential aliasing
1067 * before reading the page on the kernel side.
1068 */
1069 if (mapping_writably_mapped(mapping))
1070 flush_dcache_page(page);
1071
1072 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001073 * When a sequential read accesses a page several times,
1074 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 */
Jan Karaec0f1632007-05-06 14:49:25 -07001076 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 mark_page_accessed(page);
1078 prev_index = index;
1079
1080 /*
1081 * Ok, we have the page, and it's up-to-date, so
1082 * now we can copy it to user space...
1083 *
1084 * The actor routine returns how many bytes were actually used..
1085 * NOTE! This may not be the same as how much of a user buffer
1086 * we filled up (we may be padding etc), so we can only update
1087 * "pos" here (the actor routine has to update the user buffer
1088 * pointers and the remaining count).
1089 */
1090 ret = actor(desc, page, offset, nr);
1091 offset += ret;
1092 index += offset >> PAGE_CACHE_SHIFT;
1093 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001094 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095
1096 page_cache_release(page);
1097 if (ret == nr && desc->count)
1098 continue;
1099 goto out;
1100
1101page_not_up_to_date:
1102 /* Get exclusive access to the page ... */
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001103 if (lock_page_killable(page))
1104 goto readpage_eio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001106page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001107 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 if (!page->mapping) {
1109 unlock_page(page);
1110 page_cache_release(page);
1111 continue;
1112 }
1113
1114 /* Did somebody else fill it already? */
1115 if (PageUptodate(page)) {
1116 unlock_page(page);
1117 goto page_ok;
1118 }
1119
1120readpage:
1121 /* Start the actual read. The read will unlock the page. */
1122 error = mapping->a_ops->readpage(filp, page);
1123
Zach Brown994fc28c2005-12-15 14:28:17 -08001124 if (unlikely(error)) {
1125 if (error == AOP_TRUNCATED_PAGE) {
1126 page_cache_release(page);
1127 goto find_page;
1128 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001130 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131
1132 if (!PageUptodate(page)) {
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001133 if (lock_page_killable(page))
1134 goto readpage_eio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135 if (!PageUptodate(page)) {
1136 if (page->mapping == NULL) {
1137 /*
1138 * invalidate_inode_pages got it
1139 */
1140 unlock_page(page);
1141 page_cache_release(page);
1142 goto find_page;
1143 }
1144 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001145 shrink_readahead_size_eio(filp, ra);
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001146 goto readpage_eio;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147 }
1148 unlock_page(page);
1149 }
1150
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151 goto page_ok;
1152
Matthew Wilcox0b94e972007-12-06 11:19:57 -05001153readpage_eio:
1154 error = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155readpage_error:
1156 /* UHHUH! A synchronous read error occurred. Report it */
1157 desc->error = error;
1158 page_cache_release(page);
1159 goto out;
1160
1161no_cached_page:
1162 /*
1163 * Ok, it wasn't cached, so we need to create a new
1164 * page..
1165 */
Nick Piggineb2be182007-10-16 01:24:57 -07001166 page = page_cache_alloc_cold(mapping);
1167 if (!page) {
1168 desc->error = -ENOMEM;
1169 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 }
Nick Piggineb2be182007-10-16 01:24:57 -07001171 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172 index, GFP_KERNEL);
1173 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001174 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 if (error == -EEXIST)
1176 goto find_page;
1177 desc->error = error;
1178 goto out;
1179 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 goto readpage;
1181 }
1182
1183out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001184 ra->prev_pos = prev_index;
1185 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1186 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001188 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 if (filp)
1190 file_accessed(filp);
1191}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192
1193int file_read_actor(read_descriptor_t *desc, struct page *page,
1194 unsigned long offset, unsigned long size)
1195{
1196 char *kaddr;
1197 unsigned long left, count = desc->count;
1198
1199 if (size > count)
1200 size = count;
1201
1202 /*
1203 * Faults on the destination of a read are common, so do it before
1204 * taking the kmap.
1205 */
1206 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1207 kaddr = kmap_atomic(page, KM_USER0);
1208 left = __copy_to_user_inatomic(desc->arg.buf,
1209 kaddr + offset, size);
1210 kunmap_atomic(kaddr, KM_USER0);
1211 if (left == 0)
1212 goto success;
1213 }
1214
1215 /* Do it the slow way */
1216 kaddr = kmap(page);
1217 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1218 kunmap(page);
1219
1220 if (left) {
1221 size -= left;
1222 desc->error = -EFAULT;
1223 }
1224success:
1225 desc->count = count - size;
1226 desc->written += size;
1227 desc->arg.buf += size;
1228 return size;
1229}
1230
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001231/*
1232 * Performs necessary checks before doing a write
1233 * @iov: io vector request
1234 * @nr_segs: number of segments in the iovec
1235 * @count: number of bytes to write
1236 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1237 *
1238 * Adjust number of segments and amount of bytes to write (nr_segs should be
1239 * properly initialized first). Returns appropriate error code that caller
1240 * should return or zero in case that write should be allowed.
1241 */
1242int generic_segment_checks(const struct iovec *iov,
1243 unsigned long *nr_segs, size_t *count, int access_flags)
1244{
1245 unsigned long seg;
1246 size_t cnt = 0;
1247 for (seg = 0; seg < *nr_segs; seg++) {
1248 const struct iovec *iv = &iov[seg];
1249
1250 /*
1251 * If any segment has a negative length, or the cumulative
1252 * length ever wraps negative then return -EINVAL.
1253 */
1254 cnt += iv->iov_len;
1255 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1256 return -EINVAL;
1257 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1258 continue;
1259 if (seg == 0)
1260 return -EFAULT;
1261 *nr_segs = seg;
1262 cnt -= iv->iov_len; /* This segment is no good */
1263 break;
1264 }
1265 *count = cnt;
1266 return 0;
1267}
1268EXPORT_SYMBOL(generic_segment_checks);
1269
Randy Dunlap485bb992006-06-23 02:03:49 -07001270/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001271 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001272 * @iocb: kernel I/O control block
1273 * @iov: io vector request
1274 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001275 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001276 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001277 * This is the "read()" routine for all filesystems
1278 * that can use the page cache directly.
1279 */
1280ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001281generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1282 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283{
1284 struct file *filp = iocb->ki_filp;
1285 ssize_t retval;
1286 unsigned long seg;
1287 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001288 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
1290 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001291 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1292 if (retval)
1293 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294
1295 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1296 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001297 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298 struct address_space *mapping;
1299 struct inode *inode;
1300
1301 mapping = filp->f_mapping;
1302 inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303 if (!count)
1304 goto out; /* skip atime */
1305 size = i_size_read(inode);
1306 if (pos < size) {
Christoph Hellwiga969e902008-07-23 21:27:04 -07001307 retval = filemap_write_and_wait(mapping);
1308 if (!retval) {
1309 retval = mapping->a_ops->direct_IO(READ, iocb,
1310 iov, pos, nr_segs);
1311 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312 if (retval > 0)
1313 *ppos = pos + retval;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001314 if (retval) {
1315 file_accessed(filp);
1316 goto out;
1317 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001318 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 }
1320
Hugh Dickins11fa9772008-07-23 21:27:34 -07001321 for (seg = 0; seg < nr_segs; seg++) {
1322 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323
Hugh Dickins11fa9772008-07-23 21:27:34 -07001324 desc.written = 0;
1325 desc.arg.buf = iov[seg].iov_base;
1326 desc.count = iov[seg].iov_len;
1327 if (desc.count == 0)
1328 continue;
1329 desc.error = 0;
1330 do_generic_file_read(filp, ppos, &desc, file_read_actor);
1331 retval += desc.written;
1332 if (desc.error) {
1333 retval = retval ?: desc.error;
1334 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 }
Hugh Dickins11fa9772008-07-23 21:27:34 -07001336 if (desc.count > 0)
1337 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 }
1339out:
1340 return retval;
1341}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342EXPORT_SYMBOL(generic_file_aio_read);
1343
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344static ssize_t
1345do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001346 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347{
1348 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1349 return -EINVAL;
1350
1351 force_page_cache_readahead(mapping, filp, index,
1352 max_sane_readahead(nr));
1353 return 0;
1354}
1355
1356asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
1357{
1358 ssize_t ret;
1359 struct file *file;
1360
1361 ret = -EBADF;
1362 file = fget(fd);
1363 if (file) {
1364 if (file->f_mode & FMODE_READ) {
1365 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001366 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1367 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 unsigned long len = end - start + 1;
1369 ret = do_readahead(mapping, file, start, len);
1370 }
1371 fput(file);
1372 }
1373 return ret;
1374}
1375
1376#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001377/**
1378 * page_cache_read - adds requested page to the page cache if not already there
1379 * @file: file to read
1380 * @offset: page index
1381 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382 * This adds the requested page to the page cache if it isn't already there,
1383 * and schedules an I/O to read in its contents from disk.
1384 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001385static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386{
1387 struct address_space *mapping = file->f_mapping;
1388 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001389 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390
Zach Brown994fc28c2005-12-15 14:28:17 -08001391 do {
1392 page = page_cache_alloc_cold(mapping);
1393 if (!page)
1394 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395
Zach Brown994fc28c2005-12-15 14:28:17 -08001396 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1397 if (ret == 0)
1398 ret = mapping->a_ops->readpage(file, page);
1399 else if (ret == -EEXIST)
1400 ret = 0; /* losing race to add is OK */
1401
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
Zach Brown994fc28c2005-12-15 14:28:17 -08001404 } while (ret == AOP_TRUNCATED_PAGE);
1405
1406 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407}
1408
1409#define MMAP_LOTSAMISS (100)
1410
Randy Dunlap485bb992006-06-23 02:03:49 -07001411/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001412 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001413 * @vma: vma in which the fault was taken
1414 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001415 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001416 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 * mapped memory region to read in file data during a page fault.
1418 *
1419 * The goto's are kind of ugly, but this streamlines the normal case of having
1420 * it in the page cache, and handles the special cases reasonably without
1421 * having a lot of duplicated code.
1422 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001423int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424{
1425 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001426 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 struct address_space *mapping = file->f_mapping;
1428 struct file_ra_state *ra = &file->f_ra;
1429 struct inode *inode = mapping->host;
1430 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001431 pgoff_t size;
Nick Piggin54cb8822007-07-19 01:46:59 -07001432 int did_readaround = 0;
Nick Piggin83c54072007-07-19 01:47:05 -07001433 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001436 if (vmf->pgoff >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001437 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438
1439 /* If we don't want any read-ahead, don't bother */
Nick Piggin54cb8822007-07-19 01:46:59 -07001440 if (VM_RandomReadHint(vma))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 goto no_cached_page;
1442
1443 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444 * Do we have something in the page cache already?
1445 */
1446retry_find:
Nick Piggind0217ac2007-07-19 01:47:03 -07001447 page = find_lock_page(mapping, vmf->pgoff);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001448 /*
1449 * For sequential accesses, we use the generic readahead logic.
1450 */
1451 if (VM_SequentialReadHint(vma)) {
1452 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001453 page_cache_sync_readahead(mapping, ra, file,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001454 vmf->pgoff, 1);
1455 page = find_lock_page(mapping, vmf->pgoff);
1456 if (!page)
1457 goto no_cached_page;
1458 }
1459 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001460 page_cache_async_readahead(mapping, ra, file, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001461 vmf->pgoff, 1);
1462 }
1463 }
1464
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 if (!page) {
1466 unsigned long ra_pages;
1467
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 ra->mmap_miss++;
1469
1470 /*
1471 * Do we miss much more than hit in this file? If so,
1472 * stop bothering with read-ahead. It will only hurt.
1473 */
Fengguang Wu0bb7ba62007-10-16 01:24:32 -07001474 if (ra->mmap_miss > MMAP_LOTSAMISS)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 goto no_cached_page;
1476
1477 /*
1478 * To keep the pgmajfault counter straight, we need to
1479 * check did_readaround, as this is an inner loop.
1480 */
1481 if (!did_readaround) {
Nick Piggind0217ac2007-07-19 01:47:03 -07001482 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001483 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 }
1485 did_readaround = 1;
1486 ra_pages = max_sane_readahead(file->f_ra.ra_pages);
1487 if (ra_pages) {
1488 pgoff_t start = 0;
1489
Nick Piggind0217ac2007-07-19 01:47:03 -07001490 if (vmf->pgoff > ra_pages / 2)
1491 start = vmf->pgoff - ra_pages / 2;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 do_page_cache_readahead(mapping, file, start, ra_pages);
1493 }
Nick Piggind0217ac2007-07-19 01:47:03 -07001494 page = find_lock_page(mapping, vmf->pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 if (!page)
1496 goto no_cached_page;
1497 }
1498
1499 if (!did_readaround)
Fengguang Wu0bb7ba62007-10-16 01:24:32 -07001500 ra->mmap_miss--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501
1502 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001503 * We have a locked page in the page cache, now we need to check
1504 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 */
Nick Piggind00806b2007-07-19 01:46:57 -07001506 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 goto page_not_uptodate;
1508
Nick Piggind00806b2007-07-19 01:46:57 -07001509 /* Must recheck i_size under page lock */
1510 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001511 if (unlikely(vmf->pgoff >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001512 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001513 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001514 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001515 }
1516
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517 /*
1518 * Found the page and have a reference on it.
1519 */
1520 mark_page_accessed(page);
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001521 ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001522 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001523 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525no_cached_page:
1526 /*
1527 * We're only likely to ever get here if MADV_RANDOM is in
1528 * effect.
1529 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001530 error = page_cache_read(file, vmf->pgoff);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531
1532 /*
1533 * The page we want has now been added to the page cache.
1534 * In the unlikely event that someone removed it in the
1535 * meantime, we'll just come back here and read it again.
1536 */
1537 if (error >= 0)
1538 goto retry_find;
1539
1540 /*
1541 * An error return from page_cache_read can result if the
1542 * system is low on memory, or a problem occurs while trying
1543 * to schedule I/O.
1544 */
1545 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001546 return VM_FAULT_OOM;
1547 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548
1549page_not_uptodate:
Nick Piggind00806b2007-07-19 01:46:57 -07001550 /* IO error path */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 if (!did_readaround) {
Nick Piggind0217ac2007-07-19 01:47:03 -07001552 ret = VM_FAULT_MAJOR;
Christoph Lameterf8891e52006-06-30 01:55:45 -07001553 count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555
1556 /*
1557 * Umm, take care of errors if the page isn't up-to-date.
1558 * Try to re-read it _once_. We do this synchronously,
1559 * because there really aren't any performance issues here
1560 * and we need to check for errors.
1561 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001563 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001564 if (!error) {
1565 wait_on_page_locked(page);
1566 if (!PageUptodate(page))
1567 error = -EIO;
1568 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001570
1571 if (!error || error == AOP_TRUNCATED_PAGE)
1572 goto retry_find;
1573
1574 /* Things didn't work out. Return zero to tell the mm layer so. */
1575 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001576 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001577}
1578EXPORT_SYMBOL(filemap_fault);
1579
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001581 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582};
1583
1584/* This is used for a general mmap of a disk file */
1585
1586int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1587{
1588 struct address_space *mapping = file->f_mapping;
1589
1590 if (!mapping->a_ops->readpage)
1591 return -ENOEXEC;
1592 file_accessed(file);
1593 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001594 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001595 return 0;
1596}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597
1598/*
1599 * This is for filesystems which do not implement ->writepage.
1600 */
1601int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1602{
1603 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1604 return -EINVAL;
1605 return generic_file_mmap(file, vma);
1606}
1607#else
1608int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1609{
1610 return -ENOSYS;
1611}
1612int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1613{
1614 return -ENOSYS;
1615}
1616#endif /* CONFIG_MMU */
1617
1618EXPORT_SYMBOL(generic_file_mmap);
1619EXPORT_SYMBOL(generic_file_readonly_mmap);
1620
Nick Piggin6fe69002007-05-06 14:49:04 -07001621static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001622 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 int (*filler)(void *,struct page*),
1624 void *data)
1625{
Nick Piggineb2be182007-10-16 01:24:57 -07001626 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 int err;
1628repeat:
1629 page = find_get_page(mapping, index);
1630 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -07001631 page = page_cache_alloc_cold(mapping);
1632 if (!page)
1633 return ERR_PTR(-ENOMEM);
1634 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1635 if (unlikely(err)) {
1636 page_cache_release(page);
1637 if (err == -EEXIST)
1638 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640 return ERR_PTR(err);
1641 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 err = filler(data, page);
1643 if (err < 0) {
1644 page_cache_release(page);
1645 page = ERR_PTR(err);
1646 }
1647 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 return page;
1649}
1650
Randy Dunlap76824862008-03-19 17:00:40 -07001651/**
1652 * read_cache_page_async - read into page cache, fill it if needed
1653 * @mapping: the page's address_space
1654 * @index: the page index
1655 * @filler: function to perform the read
1656 * @data: destination for read data
1657 *
Nick Piggin6fe69002007-05-06 14:49:04 -07001658 * Same as read_cache_page, but don't wait for page to become unlocked
1659 * after submitting it to the filler.
Randy Dunlap76824862008-03-19 17:00:40 -07001660 *
1661 * Read into the page cache. If a page already exists, and PageUptodate() is
1662 * not set, try to fill the page but don't wait for it to become unlocked.
1663 *
1664 * If the page does not get brought uptodate, return -EIO.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 */
Nick Piggin6fe69002007-05-06 14:49:04 -07001666struct page *read_cache_page_async(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001667 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 int (*filler)(void *,struct page*),
1669 void *data)
1670{
1671 struct page *page;
1672 int err;
1673
1674retry:
1675 page = __read_cache_page(mapping, index, filler, data);
1676 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001677 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678 if (PageUptodate(page))
1679 goto out;
1680
1681 lock_page(page);
1682 if (!page->mapping) {
1683 unlock_page(page);
1684 page_cache_release(page);
1685 goto retry;
1686 }
1687 if (PageUptodate(page)) {
1688 unlock_page(page);
1689 goto out;
1690 }
1691 err = filler(data, page);
1692 if (err < 0) {
1693 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001694 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 }
David Howellsc855ff32007-05-09 13:42:20 +01001696out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001697 mark_page_accessed(page);
1698 return page;
1699}
1700EXPORT_SYMBOL(read_cache_page_async);
1701
1702/**
1703 * read_cache_page - read into page cache, fill it if needed
1704 * @mapping: the page's address_space
1705 * @index: the page index
1706 * @filler: function to perform the read
1707 * @data: destination for read data
1708 *
1709 * Read into the page cache. If a page already exists, and PageUptodate() is
1710 * not set, try to fill the page then wait for it to become unlocked.
1711 *
1712 * If the page does not get brought uptodate, return -EIO.
1713 */
1714struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001715 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001716 int (*filler)(void *,struct page*),
1717 void *data)
1718{
1719 struct page *page;
1720
1721 page = read_cache_page_async(mapping, index, filler, data);
1722 if (IS_ERR(page))
1723 goto out;
1724 wait_on_page_locked(page);
1725 if (!PageUptodate(page)) {
1726 page_cache_release(page);
1727 page = ERR_PTR(-EIO);
1728 }
1729 out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 return page;
1731}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732EXPORT_SYMBOL(read_cache_page);
1733
1734/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735 * The logic we want is
1736 *
1737 * if suid or (sgid and xgrp)
1738 * remove privs
1739 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001740int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741{
1742 mode_t mode = dentry->d_inode->i_mode;
1743 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744
1745 /* suid always must be killed */
1746 if (unlikely(mode & S_ISUID))
1747 kill = ATTR_KILL_SUID;
1748
1749 /*
1750 * sgid without any exec bits is just a mandatory locking mark; leave
1751 * it alone. If some exec bits are set, it's a real sgid; kill it.
1752 */
1753 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1754 kill |= ATTR_KILL_SGID;
1755
Jens Axboe01de85e2006-10-17 19:50:36 +02001756 if (unlikely(kill && !capable(CAP_FSETID)))
1757 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758
Jens Axboe01de85e2006-10-17 19:50:36 +02001759 return 0;
1760}
Mark Fashehd23a1472006-10-17 17:05:18 -07001761EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001762
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +02001763static int __remove_suid(struct dentry *dentry, int kill)
Jens Axboe01de85e2006-10-17 19:50:36 +02001764{
1765 struct iattr newattrs;
1766
1767 newattrs.ia_valid = ATTR_FORCE | kill;
1768 return notify_change(dentry, &newattrs);
1769}
1770
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001771int file_remove_suid(struct file *file)
Jens Axboe01de85e2006-10-17 19:50:36 +02001772{
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001773 struct dentry *dentry = file->f_path.dentry;
Serge E. Hallynb5376772007-10-16 23:31:36 -07001774 int killsuid = should_remove_suid(dentry);
1775 int killpriv = security_inode_need_killpriv(dentry);
1776 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001777
Serge E. Hallynb5376772007-10-16 23:31:36 -07001778 if (killpriv < 0)
1779 return killpriv;
1780 if (killpriv)
1781 error = security_inode_killpriv(dentry);
1782 if (!error && killsuid)
1783 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001784
Serge E. Hallynb5376772007-10-16 23:31:36 -07001785 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786}
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001787EXPORT_SYMBOL(file_remove_suid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788
Nick Piggin2f718ff2007-10-16 01:24:59 -07001789static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 const struct iovec *iov, size_t base, size_t bytes)
1791{
1792 size_t copied = 0, left = 0;
1793
1794 while (bytes) {
1795 char __user *buf = iov->iov_base + base;
1796 int copy = min(bytes, iov->iov_len - base);
1797
1798 base = 0;
Hiro Yoshiokac22ce142006-06-23 02:04:16 -07001799 left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 copied += copy;
1801 bytes -= copy;
1802 vaddr += copy;
1803 iov++;
1804
NeilBrown01408c42006-06-25 05:47:58 -07001805 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001806 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807 }
1808 return copied - left;
1809}
1810
1811/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001812 * Copy as much as we can into the page and return the number of bytes which
1813 * were sucessfully copied. If a fault is encountered then return the number of
1814 * bytes which were copied.
1815 */
1816size_t iov_iter_copy_from_user_atomic(struct page *page,
1817 struct iov_iter *i, unsigned long offset, size_t bytes)
1818{
1819 char *kaddr;
1820 size_t copied;
1821
1822 BUG_ON(!in_atomic());
1823 kaddr = kmap_atomic(page, KM_USER0);
1824 if (likely(i->nr_segs == 1)) {
1825 int left;
1826 char __user *buf = i->iov->iov_base + i->iov_offset;
1827 left = __copy_from_user_inatomic_nocache(kaddr + offset,
1828 buf, bytes);
1829 copied = bytes - left;
1830 } else {
1831 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1832 i->iov, i->iov_offset, bytes);
1833 }
1834 kunmap_atomic(kaddr, KM_USER0);
1835
1836 return copied;
1837}
Nick Piggin89e10782007-10-16 01:25:07 -07001838EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001839
1840/*
1841 * This has the same sideeffects and return value as
1842 * iov_iter_copy_from_user_atomic().
1843 * The difference is that it attempts to resolve faults.
1844 * Page must not be locked.
1845 */
1846size_t iov_iter_copy_from_user(struct page *page,
1847 struct iov_iter *i, unsigned long offset, size_t bytes)
1848{
1849 char *kaddr;
1850 size_t copied;
1851
1852 kaddr = kmap(page);
1853 if (likely(i->nr_segs == 1)) {
1854 int left;
1855 char __user *buf = i->iov->iov_base + i->iov_offset;
1856 left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
1857 copied = bytes - left;
1858 } else {
1859 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1860 i->iov, i->iov_offset, bytes);
1861 }
1862 kunmap(page);
1863 return copied;
1864}
Nick Piggin89e10782007-10-16 01:25:07 -07001865EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001866
Nick Pigginf7009262008-03-10 11:43:59 -07001867void iov_iter_advance(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001868{
Nick Pigginf7009262008-03-10 11:43:59 -07001869 BUG_ON(i->count < bytes);
1870
Nick Piggin2f718ff2007-10-16 01:24:59 -07001871 if (likely(i->nr_segs == 1)) {
1872 i->iov_offset += bytes;
Nick Pigginf7009262008-03-10 11:43:59 -07001873 i->count -= bytes;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001874 } else {
1875 const struct iovec *iov = i->iov;
1876 size_t base = i->iov_offset;
1877
Nick Piggin124d3b72008-02-02 15:01:17 +01001878 /*
1879 * The !iov->iov_len check ensures we skip over unlikely
Nick Pigginf7009262008-03-10 11:43:59 -07001880 * zero-length segments (without overruning the iovec).
Nick Piggin124d3b72008-02-02 15:01:17 +01001881 */
Linus Torvalds94ad3742008-07-30 14:45:12 -07001882 while (bytes || unlikely(i->count && !iov->iov_len)) {
Nick Pigginf7009262008-03-10 11:43:59 -07001883 int copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001884
Nick Pigginf7009262008-03-10 11:43:59 -07001885 copy = min(bytes, iov->iov_len - base);
1886 BUG_ON(!i->count || i->count < copy);
1887 i->count -= copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001888 bytes -= copy;
1889 base += copy;
1890 if (iov->iov_len == base) {
1891 iov++;
1892 base = 0;
1893 }
1894 }
1895 i->iov = iov;
1896 i->iov_offset = base;
1897 }
1898}
Nick Piggin89e10782007-10-16 01:25:07 -07001899EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001900
Nick Pigginafddba42007-10-16 01:25:01 -07001901/*
1902 * Fault in the first iovec of the given iov_iter, to a maximum length
1903 * of bytes. Returns 0 on success, or non-zero if the memory could not be
1904 * accessed (ie. because it is an invalid address).
1905 *
1906 * writev-intensive code may want this to prefault several iovecs -- that
1907 * would be possible (callers must not rely on the fact that _only_ the
1908 * first iovec will be faulted with the current implementation).
1909 */
1910int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001911{
Nick Piggin2f718ff2007-10-16 01:24:59 -07001912 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07001913 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
1914 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001915}
Nick Piggin89e10782007-10-16 01:25:07 -07001916EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001917
1918/*
1919 * Return the count of just the current iov_iter segment.
1920 */
1921size_t iov_iter_single_seg_count(struct iov_iter *i)
1922{
1923 const struct iovec *iov = i->iov;
1924 if (i->nr_segs == 1)
1925 return i->count;
1926 else
1927 return min(i->count, iov->iov_len - i->iov_offset);
1928}
Nick Piggin89e10782007-10-16 01:25:07 -07001929EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001930
1931/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932 * Performs necessary checks before doing a write
1933 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001934 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 * Returns appropriate error code that caller should return or
1936 * zero in case that write should be allowed.
1937 */
1938inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1939{
1940 struct inode *inode = file->f_mapping->host;
1941 unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
1942
1943 if (unlikely(*pos < 0))
1944 return -EINVAL;
1945
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 if (!isblk) {
1947 /* FIXME: this is for backwards compatibility with 2.4 */
1948 if (file->f_flags & O_APPEND)
1949 *pos = i_size_read(inode);
1950
1951 if (limit != RLIM_INFINITY) {
1952 if (*pos >= limit) {
1953 send_sig(SIGXFSZ, current, 0);
1954 return -EFBIG;
1955 }
1956 if (*count > limit - (typeof(limit))*pos) {
1957 *count = limit - (typeof(limit))*pos;
1958 }
1959 }
1960 }
1961
1962 /*
1963 * LFS rule
1964 */
1965 if (unlikely(*pos + *count > MAX_NON_LFS &&
1966 !(file->f_flags & O_LARGEFILE))) {
1967 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001968 return -EFBIG;
1969 }
1970 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
1971 *count = MAX_NON_LFS - (unsigned long)*pos;
1972 }
1973 }
1974
1975 /*
1976 * Are we about to exceed the fs block limit ?
1977 *
1978 * If we have written data it becomes a short write. If we have
1979 * exceeded without writing data we send a signal and return EFBIG.
1980 * Linus frestrict idea will clean these up nicely..
1981 */
1982 if (likely(!isblk)) {
1983 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
1984 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985 return -EFBIG;
1986 }
1987 /* zero-length writes at ->s_maxbytes are OK */
1988 }
1989
1990 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
1991 *count = inode->i_sb->s_maxbytes - *pos;
1992 } else {
David Howells93614012006-09-30 20:45:40 +02001993#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07001994 loff_t isize;
1995 if (bdev_read_only(I_BDEV(inode)))
1996 return -EPERM;
1997 isize = i_size_read(inode);
1998 if (*pos >= isize) {
1999 if (*count || *pos > isize)
2000 return -ENOSPC;
2001 }
2002
2003 if (*pos + *count > isize)
2004 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002005#else
2006 return -EPERM;
2007#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 }
2009 return 0;
2010}
2011EXPORT_SYMBOL(generic_write_checks);
2012
Nick Pigginafddba42007-10-16 01:25:01 -07002013int pagecache_write_begin(struct file *file, struct address_space *mapping,
2014 loff_t pos, unsigned len, unsigned flags,
2015 struct page **pagep, void **fsdata)
2016{
2017 const struct address_space_operations *aops = mapping->a_ops;
2018
2019 if (aops->write_begin) {
2020 return aops->write_begin(file, mapping, pos, len, flags,
2021 pagep, fsdata);
2022 } else {
2023 int ret;
2024 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
2025 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
2026 struct inode *inode = mapping->host;
2027 struct page *page;
2028again:
2029 page = __grab_cache_page(mapping, index);
2030 *pagep = page;
2031 if (!page)
2032 return -ENOMEM;
2033
2034 if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
2035 /*
2036 * There is no way to resolve a short write situation
2037 * for a !Uptodate page (except by double copying in
2038 * the caller done by generic_perform_write_2copy).
2039 *
2040 * Instead, we have to bring it uptodate here.
2041 */
2042 ret = aops->readpage(file, page);
2043 page_cache_release(page);
2044 if (ret) {
2045 if (ret == AOP_TRUNCATED_PAGE)
2046 goto again;
2047 return ret;
2048 }
2049 goto again;
2050 }
2051
2052 ret = aops->prepare_write(file, page, offset, offset+len);
2053 if (ret) {
Nick Piggin55144762007-10-16 01:25:26 -07002054 unlock_page(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002055 page_cache_release(page);
2056 if (pos + len > inode->i_size)
2057 vmtruncate(inode, inode->i_size);
Nick Pigginafddba42007-10-16 01:25:01 -07002058 }
2059 return ret;
2060 }
2061}
2062EXPORT_SYMBOL(pagecache_write_begin);
2063
2064int pagecache_write_end(struct file *file, struct address_space *mapping,
2065 loff_t pos, unsigned len, unsigned copied,
2066 struct page *page, void *fsdata)
2067{
2068 const struct address_space_operations *aops = mapping->a_ops;
2069 int ret;
2070
2071 if (aops->write_end) {
2072 mark_page_accessed(page);
2073 ret = aops->write_end(file, mapping, pos, len, copied,
2074 page, fsdata);
2075 } else {
2076 unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
2077 struct inode *inode = mapping->host;
2078
2079 flush_dcache_page(page);
2080 ret = aops->commit_write(file, page, offset, offset+len);
2081 unlock_page(page);
2082 mark_page_accessed(page);
2083 page_cache_release(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002084
2085 if (ret < 0) {
2086 if (pos + len > inode->i_size)
2087 vmtruncate(inode, inode->i_size);
2088 } else if (ret > 0)
2089 ret = min_t(size_t, copied, ret);
2090 else
2091 ret = copied;
2092 }
2093
2094 return ret;
2095}
2096EXPORT_SYMBOL(pagecache_write_end);
2097
Linus Torvalds1da177e2005-04-16 15:20:36 -07002098ssize_t
2099generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2100 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2101 size_t count, size_t ocount)
2102{
2103 struct file *file = iocb->ki_filp;
2104 struct address_space *mapping = file->f_mapping;
2105 struct inode *inode = mapping->host;
2106 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002107 size_t write_len;
2108 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109
2110 if (count != ocount)
2111 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2112
Christoph Hellwiga969e902008-07-23 21:27:04 -07002113 /*
2114 * Unmap all mmappings of the file up-front.
2115 *
2116 * This will cause any pte dirty bits to be propagated into the
2117 * pageframes for the subsequent filemap_write_and_wait().
2118 */
2119 write_len = iov_length(iov, *nr_segs);
2120 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
2121 if (mapping_mapped(mapping))
2122 unmap_mapping_range(mapping, pos, write_len, 0);
2123
2124 written = filemap_write_and_wait(mapping);
2125 if (written)
2126 goto out;
2127
2128 /*
2129 * After a write we want buffered reads to be sure to go to disk to get
2130 * the new data. We invalidate clean cached page from the region we're
2131 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002132 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002133 */
2134 if (mapping->nrpages) {
2135 written = invalidate_inode_pages2_range(mapping,
2136 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002137 /*
2138 * If a page can not be invalidated, return 0 to fall back
2139 * to buffered write.
2140 */
2141 if (written) {
2142 if (written == -EBUSY)
2143 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002144 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002145 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002146 }
2147
2148 written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2149
2150 /*
2151 * Finally, try again to invalidate clean pages which might have been
2152 * cached by non-direct readahead, or faulted in by get_user_pages()
2153 * if the source of the write was an mmap'ed region of the file
2154 * we're writing. Either one is a pretty crazy thing to do,
2155 * so we don't support it 100%. If this invalidation
2156 * fails, tough, the write still worked...
2157 */
2158 if (mapping->nrpages) {
2159 invalidate_inode_pages2_range(mapping,
2160 pos >> PAGE_CACHE_SHIFT, end);
2161 }
2162
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 if (written > 0) {
2164 loff_t end = pos + written;
2165 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2166 i_size_write(inode, end);
2167 mark_inode_dirty(inode);
2168 }
2169 *ppos = end;
2170 }
2171
2172 /*
2173 * Sync the fs metadata but not the minor inode changes and
2174 * of course not the data as we did direct DMA for the IO.
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002175 * i_mutex is held, which protects generic_osync_inode() from
Zach Brown8459d862006-12-10 02:21:05 -08002176 * livelocking. AIO O_DIRECT ops attempt to sync metadata here.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177 */
Christoph Hellwiga969e902008-07-23 21:27:04 -07002178out:
Zach Brown8459d862006-12-10 02:21:05 -08002179 if ((written >= 0 || written == -EIOCBQUEUED) &&
2180 ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Hifumi Hisashi1e8a81c2005-06-25 14:54:32 -07002181 int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
2182 if (err < 0)
2183 written = err;
2184 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 return written;
2186}
2187EXPORT_SYMBOL(generic_file_direct_write);
2188
Nick Piggineb2be182007-10-16 01:24:57 -07002189/*
2190 * Find or create a page at the given pagecache position. Return the locked
2191 * page. This function is specifically for buffered writes.
2192 */
Nick Pigginafddba42007-10-16 01:25:01 -07002193struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index)
Nick Piggineb2be182007-10-16 01:24:57 -07002194{
2195 int status;
2196 struct page *page;
2197repeat:
2198 page = find_lock_page(mapping, index);
2199 if (likely(page))
2200 return page;
2201
2202 page = page_cache_alloc(mapping);
2203 if (!page)
2204 return NULL;
2205 status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
2206 if (unlikely(status)) {
2207 page_cache_release(page);
2208 if (status == -EEXIST)
2209 goto repeat;
2210 return NULL;
2211 }
2212 return page;
2213}
Nick Pigginafddba42007-10-16 01:25:01 -07002214EXPORT_SYMBOL(__grab_cache_page);
Nick Piggineb2be182007-10-16 01:24:57 -07002215
Nick Pigginafddba42007-10-16 01:25:01 -07002216static ssize_t generic_perform_write_2copy(struct file *file,
2217 struct iov_iter *i, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218{
Andrew Mortonae374612007-10-16 01:24:55 -07002219 struct address_space *mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002220 const struct address_space_operations *a_ops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002221 struct inode *inode = mapping->host;
2222 long status = 0;
2223 ssize_t written = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224
2225 do {
Nick Piggin08291422007-10-16 01:24:59 -07002226 struct page *src_page;
Nick Piggineb2be182007-10-16 01:24:57 -07002227 struct page *page;
Andrew Mortonae374612007-10-16 01:24:55 -07002228 pgoff_t index; /* Pagecache index for current page */
2229 unsigned long offset; /* Offset into pagecache page */
Nick Piggin08291422007-10-16 01:24:59 -07002230 unsigned long bytes; /* Bytes to write to page */
Andrew Mortonae374612007-10-16 01:24:55 -07002231 size_t copied; /* Bytes copied from user */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232
Andrew Mortonae374612007-10-16 01:24:55 -07002233 offset = (pos & (PAGE_CACHE_SIZE - 1));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002234 index = pos >> PAGE_CACHE_SHIFT;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002235 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
Nick Pigginafddba42007-10-16 01:25:01 -07002236 iov_iter_count(i));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237
Nick Piggin08291422007-10-16 01:24:59 -07002238 /*
2239 * a non-NULL src_page indicates that we're doing the
2240 * copy via get_user_pages and kmap.
2241 */
2242 src_page = NULL;
Andrew Mortonae374612007-10-16 01:24:55 -07002243
Nick Piggin41cb8ac2007-10-16 01:24:53 -07002244 /*
2245 * Bring in the user page that we will copy from _first_.
2246 * Otherwise there's a nasty deadlock on copying from the
2247 * same page as we're writing to, without it being marked
2248 * up-to-date.
Nick Piggin08291422007-10-16 01:24:59 -07002249 *
2250 * Not only is this an optimisation, but it is also required
2251 * to check that the address is actually valid, when atomic
2252 * usercopies are used, below.
Nick Piggin41cb8ac2007-10-16 01:24:53 -07002253 */
Nick Pigginafddba42007-10-16 01:25:01 -07002254 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
Nick Piggin08291422007-10-16 01:24:59 -07002255 status = -EFAULT;
2256 break;
2257 }
Nick Piggineb2be182007-10-16 01:24:57 -07002258
2259 page = __grab_cache_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260 if (!page) {
2261 status = -ENOMEM;
2262 break;
2263 }
2264
Nick Piggin08291422007-10-16 01:24:59 -07002265 /*
2266 * non-uptodate pages cannot cope with short copies, and we
2267 * cannot take a pagefault with the destination page locked.
2268 * So pin the source page to copy it.
2269 */
Nick Piggin674b8922007-10-16 01:25:03 -07002270 if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
Nick Piggin08291422007-10-16 01:24:59 -07002271 unlock_page(page);
2272
2273 src_page = alloc_page(GFP_KERNEL);
2274 if (!src_page) {
2275 page_cache_release(page);
2276 status = -ENOMEM;
2277 break;
2278 }
2279
2280 /*
2281 * Cannot get_user_pages with a page locked for the
2282 * same reason as we can't take a page fault with a
2283 * page locked (as explained below).
2284 */
Nick Pigginafddba42007-10-16 01:25:01 -07002285 copied = iov_iter_copy_from_user(src_page, i,
Nick Piggin2f718ff2007-10-16 01:24:59 -07002286 offset, bytes);
Nick Piggin08291422007-10-16 01:24:59 -07002287 if (unlikely(copied == 0)) {
2288 status = -EFAULT;
2289 page_cache_release(page);
2290 page_cache_release(src_page);
2291 break;
2292 }
2293 bytes = copied;
2294
2295 lock_page(page);
2296 /*
2297 * Can't handle the page going uptodate here, because
2298 * that means we would use non-atomic usercopies, which
2299 * zero out the tail of the page, which can cause
2300 * zeroes to become transiently visible. We could just
2301 * use a non-zeroing copy, but the APIs aren't too
2302 * consistent.
2303 */
2304 if (unlikely(!page->mapping || PageUptodate(page))) {
2305 unlock_page(page);
2306 page_cache_release(page);
2307 page_cache_release(src_page);
2308 continue;
2309 }
Nick Piggin08291422007-10-16 01:24:59 -07002310 }
2311
Linus Torvalds1da177e2005-04-16 15:20:36 -07002312 status = a_ops->prepare_write(file, page, offset, offset+bytes);
Nick Piggin64649a52007-10-16 01:24:56 -07002313 if (unlikely(status))
2314 goto fs_write_aop_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08002315
Nick Piggin08291422007-10-16 01:24:59 -07002316 if (!src_page) {
2317 /*
2318 * Must not enter the pagefault handler here, because
2319 * we hold the page lock, so we might recursively
2320 * deadlock on the same lock, or get an ABBA deadlock
2321 * against a different lock, or against the mmap_sem
2322 * (which nests outside the page lock). So increment
2323 * preempt count, and use _atomic usercopies.
2324 *
2325 * The page is uptodate so we are OK to encounter a
2326 * short copy: if unmodified parts of the page are
2327 * marked dirty and written out to disk, it doesn't
2328 * really matter.
2329 */
2330 pagefault_disable();
Nick Pigginafddba42007-10-16 01:25:01 -07002331 copied = iov_iter_copy_from_user_atomic(page, i,
Nick Piggin2f718ff2007-10-16 01:24:59 -07002332 offset, bytes);
Nick Piggin08291422007-10-16 01:24:59 -07002333 pagefault_enable();
2334 } else {
2335 void *src, *dst;
2336 src = kmap_atomic(src_page, KM_USER0);
2337 dst = kmap_atomic(page, KM_USER1);
2338 memcpy(dst + offset, src + offset, bytes);
2339 kunmap_atomic(dst, KM_USER1);
2340 kunmap_atomic(src, KM_USER0);
2341 copied = bytes;
2342 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002343 flush_dcache_page(page);
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002344
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 status = a_ops->commit_write(file, page, offset, offset+bytes);
Nick Piggin55144762007-10-16 01:25:26 -07002346 if (unlikely(status < 0))
Nick Piggin64649a52007-10-16 01:24:56 -07002347 goto fs_write_aop_error;
Nick Piggin64649a52007-10-16 01:24:56 -07002348 if (unlikely(status > 0)) /* filesystem did partial write */
Nick Piggin08291422007-10-16 01:24:59 -07002349 copied = min_t(size_t, copied, status);
2350
2351 unlock_page(page);
2352 mark_page_accessed(page);
2353 page_cache_release(page);
2354 if (src_page)
2355 page_cache_release(src_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356
Nick Pigginafddba42007-10-16 01:25:01 -07002357 iov_iter_advance(i, copied);
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002358 pos += copied;
Nick Pigginafddba42007-10-16 01:25:01 -07002359 written += copied;
Nick Piggin4a9e5ef2007-10-16 01:24:58 -07002360
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 balance_dirty_pages_ratelimited(mapping);
2362 cond_resched();
Nick Piggin64649a52007-10-16 01:24:56 -07002363 continue;
2364
2365fs_write_aop_error:
Nick Piggin55144762007-10-16 01:25:26 -07002366 unlock_page(page);
Nick Piggin64649a52007-10-16 01:24:56 -07002367 page_cache_release(page);
Nick Piggin08291422007-10-16 01:24:59 -07002368 if (src_page)
2369 page_cache_release(src_page);
Nick Piggin64649a52007-10-16 01:24:56 -07002370
2371 /*
2372 * prepare_write() may have instantiated a few blocks
2373 * outside i_size. Trim these off again. Don't need
2374 * i_size_read because we hold i_mutex.
2375 */
2376 if (pos + bytes > inode->i_size)
2377 vmtruncate(inode, inode->i_size);
Nick Piggin55144762007-10-16 01:25:26 -07002378 break;
Nick Pigginafddba42007-10-16 01:25:01 -07002379 } while (iov_iter_count(i));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002380
Nick Pigginafddba42007-10-16 01:25:01 -07002381 return written ? written : status;
2382}
2383
2384static ssize_t generic_perform_write(struct file *file,
2385 struct iov_iter *i, loff_t pos)
2386{
2387 struct address_space *mapping = file->f_mapping;
2388 const struct address_space_operations *a_ops = mapping->a_ops;
2389 long status = 0;
2390 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002391 unsigned int flags = 0;
2392
2393 /*
2394 * Copies from kernel address space cannot fail (NFSD is a big user).
2395 */
2396 if (segment_eq(get_fs(), KERNEL_DS))
2397 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002398
2399 do {
2400 struct page *page;
2401 pgoff_t index; /* Pagecache index for current page */
2402 unsigned long offset; /* Offset into pagecache page */
2403 unsigned long bytes; /* Bytes to write to page */
2404 size_t copied; /* Bytes copied from user */
2405 void *fsdata;
2406
2407 offset = (pos & (PAGE_CACHE_SIZE - 1));
2408 index = pos >> PAGE_CACHE_SHIFT;
2409 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2410 iov_iter_count(i));
2411
2412again:
2413
2414 /*
2415 * Bring in the user page that we will copy from _first_.
2416 * Otherwise there's a nasty deadlock on copying from the
2417 * same page as we're writing to, without it being marked
2418 * up-to-date.
2419 *
2420 * Not only is this an optimisation, but it is also required
2421 * to check that the address is actually valid, when atomic
2422 * usercopies are used, below.
2423 */
2424 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2425 status = -EFAULT;
2426 break;
2427 }
2428
Nick Piggin674b8922007-10-16 01:25:03 -07002429 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002430 &page, &fsdata);
2431 if (unlikely(status))
2432 break;
2433
2434 pagefault_disable();
2435 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2436 pagefault_enable();
2437 flush_dcache_page(page);
2438
2439 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2440 page, fsdata);
2441 if (unlikely(status < 0))
2442 break;
2443 copied = status;
2444
2445 cond_resched();
2446
Nick Piggin124d3b72008-02-02 15:01:17 +01002447 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002448 if (unlikely(copied == 0)) {
2449 /*
2450 * If we were unable to copy any data at all, we must
2451 * fall back to a single segment length write.
2452 *
2453 * If we didn't fallback here, we could livelock
2454 * because not all segments in the iov can be copied at
2455 * once without a pagefault.
2456 */
2457 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2458 iov_iter_single_seg_count(i));
2459 goto again;
2460 }
Nick Pigginafddba42007-10-16 01:25:01 -07002461 pos += copied;
2462 written += copied;
2463
2464 balance_dirty_pages_ratelimited(mapping);
2465
2466 } while (iov_iter_count(i));
2467
2468 return written ? written : status;
2469}
2470
2471ssize_t
2472generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2473 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2474 size_t count, ssize_t written)
2475{
2476 struct file *file = iocb->ki_filp;
2477 struct address_space *mapping = file->f_mapping;
2478 const struct address_space_operations *a_ops = mapping->a_ops;
2479 struct inode *inode = mapping->host;
2480 ssize_t status;
2481 struct iov_iter i;
2482
2483 iov_iter_init(&i, iov, nr_segs, count, written);
2484 if (a_ops->write_begin)
2485 status = generic_perform_write(file, &i, pos);
2486 else
2487 status = generic_perform_write_2copy(file, &i, pos);
2488
Linus Torvalds1da177e2005-04-16 15:20:36 -07002489 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002490 written += status;
2491 *ppos = pos + status;
2492
2493 /*
2494 * For now, when the user asks for O_SYNC, we'll actually give
2495 * O_DSYNC
2496 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497 if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2498 if (!a_ops->writepage || !is_sync_kiocb(iocb))
2499 status = generic_osync_inode(inode, mapping,
2500 OSYNC_METADATA|OSYNC_DATA);
2501 }
2502 }
2503
2504 /*
2505 * If we get here for O_DIRECT writes then we must have fallen through
2506 * to buffered writes (block instantiation inside i_size). So we sync
2507 * the file data here, to try to honour O_DIRECT expectations.
2508 */
2509 if (unlikely(file->f_flags & O_DIRECT) && written)
2510 status = filemap_write_and_wait(mapping);
2511
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512 return written ? written : status;
2513}
2514EXPORT_SYMBOL(generic_file_buffered_write);
2515
Adrian Bunk5ce78522005-09-10 00:26:28 -07002516static ssize_t
Linus Torvalds1da177e2005-04-16 15:20:36 -07002517__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
2518 unsigned long nr_segs, loff_t *ppos)
2519{
2520 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002521 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522 size_t ocount; /* original count */
2523 size_t count; /* after file limit checks */
2524 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002525 loff_t pos;
2526 ssize_t written;
2527 ssize_t err;
2528
2529 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002530 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2531 if (err)
2532 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533
2534 count = ocount;
2535 pos = *ppos;
2536
2537 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2538
2539 /* We can write back this queue in page reclaim */
2540 current->backing_dev_info = mapping->backing_dev_info;
2541 written = 0;
2542
2543 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2544 if (err)
2545 goto out;
2546
2547 if (count == 0)
2548 goto out;
2549
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002550 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002551 if (err)
2552 goto out;
2553
Christoph Hellwig870f4812006-01-09 20:52:01 -08002554 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555
2556 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2557 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002558 loff_t endbyte;
2559 ssize_t written_buffered;
2560
2561 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2562 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002563 if (written < 0 || written == count)
2564 goto out;
2565 /*
2566 * direct-io write to a hole: fall through to buffered I/O
2567 * for completing the rest of the request.
2568 */
2569 pos += written;
2570 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002571 written_buffered = generic_file_buffered_write(iocb, iov,
2572 nr_segs, pos, ppos, count,
2573 written);
2574 /*
2575 * If generic_file_buffered_write() retuned a synchronous error
2576 * then we want to return the number of bytes which were
2577 * direct-written, or the error code if that was zero. Note
2578 * that this differs from normal direct-io semantics, which
2579 * will return -EFOO even if some bytes were written.
2580 */
2581 if (written_buffered < 0) {
2582 err = written_buffered;
2583 goto out;
2584 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002585
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002586 /*
2587 * We need to ensure that the page cache pages are written to
2588 * disk and invalidated to preserve the expected O_DIRECT
2589 * semantics.
2590 */
2591 endbyte = pos + written_buffered - written - 1;
Mark Fashehef51c972007-05-08 00:27:10 -07002592 err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
2593 SYNC_FILE_RANGE_WAIT_BEFORE|
2594 SYNC_FILE_RANGE_WRITE|
2595 SYNC_FILE_RANGE_WAIT_AFTER);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002596 if (err == 0) {
2597 written = written_buffered;
2598 invalidate_mapping_pages(mapping,
2599 pos >> PAGE_CACHE_SHIFT,
2600 endbyte >> PAGE_CACHE_SHIFT);
2601 } else {
2602 /*
2603 * We don't know how much we wrote, so just return
2604 * the number of bytes which were direct-written
2605 */
2606 }
2607 } else {
2608 written = generic_file_buffered_write(iocb, iov, nr_segs,
2609 pos, ppos, count, written);
2610 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002611out:
2612 current->backing_dev_info = NULL;
2613 return written ? written : err;
2614}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002615
Badari Pulavarty027445c2006-09-30 23:28:46 -07002616ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
2617 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002618{
2619 struct file *file = iocb->ki_filp;
2620 struct address_space *mapping = file->f_mapping;
2621 struct inode *inode = mapping->host;
2622 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623
Badari Pulavarty027445c2006-09-30 23:28:46 -07002624 BUG_ON(iocb->ki_pos != pos);
2625
2626 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2627 &iocb->ki_pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002628
2629 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
Badari Pulavarty027445c2006-09-30 23:28:46 -07002630 ssize_t err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631
2632 err = sync_page_range_nolock(inode, mapping, pos, ret);
2633 if (err < 0)
2634 ret = err;
2635 }
2636 return ret;
2637}
Badari Pulavarty027445c2006-09-30 23:28:46 -07002638EXPORT_SYMBOL(generic_file_aio_write_nolock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639
Badari Pulavarty027445c2006-09-30 23:28:46 -07002640ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2641 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642{
2643 struct file *file = iocb->ki_filp;
2644 struct address_space *mapping = file->f_mapping;
2645 struct inode *inode = mapping->host;
2646 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647
2648 BUG_ON(iocb->ki_pos != pos);
2649
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002650 mutex_lock(&inode->i_mutex);
Badari Pulavarty027445c2006-09-30 23:28:46 -07002651 ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
2652 &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002653 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654
2655 if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
2656 ssize_t err;
2657
2658 err = sync_page_range(inode, mapping, pos, ret);
2659 if (err < 0)
2660 ret = err;
2661 }
2662 return ret;
2663}
2664EXPORT_SYMBOL(generic_file_aio_write);
2665
David Howellscf9a2ae2006-08-29 19:05:54 +01002666/**
2667 * try_to_release_page() - release old fs-specific metadata on a page
2668 *
2669 * @page: the page which the kernel is trying to free
2670 * @gfp_mask: memory allocation flags (and I/O mode)
2671 *
2672 * The address_space is to try to release any data against the page
2673 * (presumably at page->private). If the release was successful, return `1'.
2674 * Otherwise return zero.
2675 *
2676 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fdd2008-07-25 01:46:22 -07002677 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002678 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002679 */
2680int try_to_release_page(struct page *page, gfp_t gfp_mask)
2681{
2682 struct address_space * const mapping = page->mapping;
2683
2684 BUG_ON(!PageLocked(page));
2685 if (PageWriteback(page))
2686 return 0;
2687
2688 if (mapping && mapping->a_ops->releasepage)
2689 return mapping->a_ops->releasepage(page, gfp_mask);
2690 return try_to_free_buffers(page);
2691}
2692
2693EXPORT_SYMBOL(try_to_release_page);