blob: 88d719665a28e8f28b66a9fadffa933ae46b1875 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070013#include <linux/compiler.h>
14#include <linux/fs.h>
Hiro Yoshiokac22ce142006-06-23 02:04:16 -070015#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/aio.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080017#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/kernel_stat.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090019#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#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>
Rik van Riel4f98a2f2008-10-18 20:26:32 -070036#include <linux/mm_inline.h> /* for page_is_file_cache() */
Nick Piggin0f8053a2006-03-22 00:08:33 -080037#include "internal.h"
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070040 * FIXME: remove all knowledge of the buffer layer from the core VM
41 */
Jan Kara148f9482009-08-17 19:52:36 +020042#include <linux/buffer_head.h> /* for try_to_free_buffers */
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
Linus Torvalds1da177e2005-04-16 15:20:36 -070044#include <asm/mman.h>
45
46/*
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 *
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100061 * ->i_mmap_lock (truncate_pagecache)
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 * ->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)
Andi Kleen6a460792009-09-16 11:50:15 +0200107 *
108 * (code doesn't rely on that order, so you could switch it around)
109 * ->tasklist_lock (memory_failure, collect_procs_ao)
110 * ->i_mmap_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 */
112
113/*
114 * Remove a page from the page cache and free it. Caller has to make
115 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700116 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 */
118void __remove_from_page_cache(struct page *page)
119{
120 struct address_space *mapping = page->mapping;
121
122 radix_tree_delete(&mapping->page_tree, page->index);
123 page->mapping = NULL;
124 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700125 __dec_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700126 if (PageSwapBacked(page))
127 __dec_zone_page_state(page, NR_SHMEM);
Nick Piggin45426812007-07-15 23:38:12 -0700128 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800129
130 /*
131 * Some filesystems seem to re-dirty the page even after
132 * the VM has canceled the dirty bit (eg ext3 journaling).
133 *
134 * Fix it up by doing a final dirty accounting check after
135 * having removed the page entirely.
136 */
137 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
138 dec_zone_page_state(page, NR_FILE_DIRTY);
139 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
140 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141}
142
143void remove_from_page_cache(struct page *page)
144{
145 struct address_space *mapping = page->mapping;
146
Matt Mackallcd7619d2005-05-01 08:59:01 -0700147 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148
Nick Piggin19fd6232008-07-25 19:45:32 -0700149 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700151 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700152 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153}
154
155static int sync_page(void *word)
156{
157 struct address_space *mapping;
158 struct page *page;
159
Andi Kleen07808b72005-11-05 17:25:53 +0100160 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
162 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700163 * page_mapping() is being called without PG_locked held.
164 * Some knowledge of the state and use of the page is used to
165 * reduce the requirements down to a memory barrier.
166 * The danger here is of a stale page_mapping() return value
167 * indicating a struct address_space different from the one it's
168 * associated with when it is associated with one.
169 * After smp_mb(), it's either the correct page_mapping() for
170 * the page, or an old page_mapping() and the page's own
171 * page_mapping() has gone NULL.
172 * The ->sync_page() address_space operation must tolerate
173 * page_mapping() going NULL. By an amazing coincidence,
174 * this comes about because none of the users of the page
175 * in the ->sync_page() methods make essential use of the
176 * page_mapping(), merely passing the page down to the backing
177 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700178 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700179 * of interest. When page_mapping() does go NULL, the entire
180 * call stack gracefully ignores the page and returns.
181 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 */
183 smp_mb();
184 mapping = page_mapping(page);
185 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
186 mapping->a_ops->sync_page(page);
187 io_schedule();
188 return 0;
189}
190
Matthew Wilcox2687a352007-12-06 11:18:49 -0500191static int sync_page_killable(void *word)
192{
193 sync_page(word);
194 return fatal_signal_pending(current) ? -EINTR : 0;
195}
196
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700198 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700199 * @mapping: address space structure to write
200 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800201 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700202 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700204 * Start writeback against all of a mapping's dirty pages that lie
205 * within the byte offsets <start, end> inclusive.
206 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700208 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 * these two operations is that if a dirty page/buffer is encountered, it must
210 * be waited upon, and not just skipped over.
211 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800212int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
213 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214{
215 int ret;
216 struct writeback_control wbc = {
217 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800218 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700219 .range_start = start,
220 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 };
222
223 if (!mapping_cap_writeback_dirty(mapping))
224 return 0;
225
226 ret = do_writepages(mapping, &wbc);
227 return ret;
228}
229
230static inline int __filemap_fdatawrite(struct address_space *mapping,
231 int sync_mode)
232{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700233 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234}
235
236int filemap_fdatawrite(struct address_space *mapping)
237{
238 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
239}
240EXPORT_SYMBOL(filemap_fdatawrite);
241
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400242int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800243 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244{
245 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
246}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400247EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248
Randy Dunlap485bb992006-06-23 02:03:49 -0700249/**
250 * filemap_flush - mostly a non-blocking flush
251 * @mapping: target address_space
252 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 * This is a mostly non-blocking flush. Not suitable for data-integrity
254 * purposes - I/O may not be started against all dirty pages.
255 */
256int filemap_flush(struct address_space *mapping)
257{
258 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
259}
260EXPORT_SYMBOL(filemap_flush);
261
Randy Dunlap485bb992006-06-23 02:03:49 -0700262/**
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200263 * filemap_fdatawait_range - wait for writeback to complete
264 * @mapping: address space structure to wait for
265 * @start_byte: offset in bytes where the range starts
266 * @end_byte: offset in bytes where the range ends (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -0700267 *
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200268 * Walk the list of under-writeback pages of the given address space
269 * in the given range and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 */
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200271int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
272 loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273{
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200274 pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
275 pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 struct pagevec pvec;
277 int nr_pages;
278 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200280 if (end_byte < start_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 return 0;
282
283 pagevec_init(&pvec, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 while ((index <= end) &&
285 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
286 PAGECACHE_TAG_WRITEBACK,
287 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
288 unsigned i;
289
290 for (i = 0; i < nr_pages; i++) {
291 struct page *page = pvec.pages[i];
292
293 /* until radix tree lookup accepts end_index */
294 if (page->index > end)
295 continue;
296
297 wait_on_page_writeback(page);
298 if (PageError(page))
299 ret = -EIO;
300 }
301 pagevec_release(&pvec);
302 cond_resched();
303 }
304
305 /* Check for outstanding write errors */
306 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
307 ret = -ENOSPC;
308 if (test_and_clear_bit(AS_EIO, &mapping->flags))
309 ret = -EIO;
310
311 return ret;
312}
Jan Karad3bccb6f2009-08-17 19:30:27 +0200313EXPORT_SYMBOL(filemap_fdatawait_range);
314
315/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700316 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700318 *
319 * Walk the list of under-writeback pages of the given address space
320 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 */
322int filemap_fdatawait(struct address_space *mapping)
323{
324 loff_t i_size = i_size_read(mapping->host);
325
326 if (i_size == 0)
327 return 0;
328
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200329 return filemap_fdatawait_range(mapping, 0, i_size - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330}
331EXPORT_SYMBOL(filemap_fdatawait);
332
333int filemap_write_and_wait(struct address_space *mapping)
334{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800335 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336
337 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800338 err = filemap_fdatawrite(mapping);
339 /*
340 * Even if the above returned error, the pages may be
341 * written partially (e.g. -ENOSPC), so we wait for it.
342 * But the -EIO is special case, it may indicate the worst
343 * thing (e.g. bug) happened, so we avoid waiting for it.
344 */
345 if (err != -EIO) {
346 int err2 = filemap_fdatawait(mapping);
347 if (!err)
348 err = err2;
349 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800351 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800353EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
Randy Dunlap485bb992006-06-23 02:03:49 -0700355/**
356 * filemap_write_and_wait_range - write out & wait on a file range
357 * @mapping: the address_space for the pages
358 * @lstart: offset in bytes where the range starts
359 * @lend: offset in bytes where the range ends (inclusive)
360 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800361 * Write out and wait upon file offsets lstart->lend, inclusive.
362 *
363 * Note that `lend' is inclusive (describes the last byte to be written) so
364 * that this function can be used to write to the very end-of-file (end = -1).
365 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366int filemap_write_and_wait_range(struct address_space *mapping,
367 loff_t lstart, loff_t lend)
368{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800369 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370
371 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800372 err = __filemap_fdatawrite_range(mapping, lstart, lend,
373 WB_SYNC_ALL);
374 /* See comment of filemap_write_and_wait() */
375 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200376 int err2 = filemap_fdatawait_range(mapping,
377 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800378 if (!err)
379 err = err2;
380 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700381 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800382 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383}
Chris Masonf6995582009-04-15 13:22:37 -0400384EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
Randy Dunlap485bb992006-06-23 02:03:49 -0700386/**
Nick Piggine2867812008-07-25 19:45:30 -0700387 * add_to_page_cache_locked - add a locked page to the pagecache
Randy Dunlap485bb992006-06-23 02:03:49 -0700388 * @page: page to add
389 * @mapping: the page's address_space
390 * @offset: page index
391 * @gfp_mask: page allocation mode
392 *
Nick Piggine2867812008-07-25 19:45:30 -0700393 * This function is used to add a page to the pagecache. It must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394 * This function does not add the page to the LRU. The caller must do that.
395 */
Nick Piggine2867812008-07-25 19:45:30 -0700396int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400397 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398{
Nick Piggine2867812008-07-25 19:45:30 -0700399 int error;
400
401 VM_BUG_ON(!PageLocked(page));
402
403 error = mem_cgroup_cache_charge(page, current->mm,
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -0800404 gfp_mask & GFP_RECLAIM_MASK);
Balbir Singh35c754d2008-02-07 00:14:05 -0800405 if (error)
406 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407
Balbir Singh35c754d2008-02-07 00:14:05 -0800408 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 if (error == 0) {
Nick Piggine2867812008-07-25 19:45:30 -0700410 page_cache_get(page);
411 page->mapping = mapping;
412 page->index = offset;
413
Nick Piggin19fd6232008-07-25 19:45:32 -0700414 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 error = radix_tree_insert(&mapping->page_tree, offset, page);
Nick Piggine2867812008-07-25 19:45:30 -0700416 if (likely(!error)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700418 __inc_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700419 if (PageSwapBacked(page))
420 __inc_zone_page_state(page, NR_SHMEM);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700421 spin_unlock_irq(&mapping->tree_lock);
Nick Piggine2867812008-07-25 19:45:30 -0700422 } else {
423 page->mapping = NULL;
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700424 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700425 mem_cgroup_uncharge_cache_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700426 page_cache_release(page);
427 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800429 } else
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700430 mem_cgroup_uncharge_cache_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800431out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 return error;
433}
Nick Piggine2867812008-07-25 19:45:30 -0700434EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435
436int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400437 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700439 int ret;
440
441 /*
442 * Splice_read and readahead add shmem/tmpfs pages into the page cache
443 * before shmem_readpage has a chance to mark them as SwapBacked: they
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700444 * need to go on the anon lru below, and mem_cgroup_cache_charge
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700445 * (called in add_to_page_cache) needs to know where they're going too.
446 */
447 if (mapping_cap_swap_backed(mapping))
448 SetPageSwapBacked(page);
449
450 ret = add_to_page_cache(page, mapping, offset, gfp_mask);
451 if (ret == 0) {
452 if (page_is_file_cache(page))
453 lru_cache_add_file(page);
454 else
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700455 lru_cache_add_anon(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700456 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 return ret;
458}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300459EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460
Paul Jackson44110fe2006-03-24 03:16:04 -0800461#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700462struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800463{
Miao Xiec0ff7452010-05-24 14:32:08 -0700464 int n;
465 struct page *page;
466
Paul Jackson44110fe2006-03-24 03:16:04 -0800467 if (cpuset_do_page_mem_spread()) {
Miao Xiec0ff7452010-05-24 14:32:08 -0700468 get_mems_allowed();
469 n = cpuset_mem_spread_node();
470 page = alloc_pages_exact_node(n, gfp, 0);
471 put_mems_allowed();
472 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800473 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700474 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800475}
Nick Piggin2ae88142006-10-28 10:38:23 -0700476EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800477#endif
478
Nick Piggindb376482006-09-25 23:31:24 -0700479static int __sleep_on_page_lock(void *word)
480{
481 io_schedule();
482 return 0;
483}
484
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485/*
486 * In order to wait for pages to become available there must be
487 * waitqueues associated with pages. By using a hash table of
488 * waitqueues where the bucket discipline is to maintain all
489 * waiters on the same queue and wake all when any of the pages
490 * become available, and for the woken contexts to check to be
491 * sure the appropriate page became available, this saves space
492 * at a cost of "thundering herd" phenomena during rare hash
493 * collisions.
494 */
495static wait_queue_head_t *page_waitqueue(struct page *page)
496{
497 const struct zone *zone = page_zone(page);
498
499 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
500}
501
502static inline void wake_up_page(struct page *page, int bit)
503{
504 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
505}
506
Harvey Harrison920c7a52008-02-04 22:29:26 -0800507void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508{
509 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
510
511 if (test_bit(bit_nr, &page->flags))
512 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
513 TASK_UNINTERRUPTIBLE);
514}
515EXPORT_SYMBOL(wait_on_page_bit);
516
517/**
David Howells385e1ca5f2009-04-03 16:42:39 +0100518 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -0700519 * @page: Page defining the wait queue of interest
520 * @waiter: Waiter to add to the queue
David Howells385e1ca5f2009-04-03 16:42:39 +0100521 *
522 * Add an arbitrary @waiter to the wait queue for the nominated @page.
523 */
524void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
525{
526 wait_queue_head_t *q = page_waitqueue(page);
527 unsigned long flags;
528
529 spin_lock_irqsave(&q->lock, flags);
530 __add_wait_queue(q, waiter);
531 spin_unlock_irqrestore(&q->lock, flags);
532}
533EXPORT_SYMBOL_GPL(add_page_wait_queue);
534
535/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700536 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537 * @page: the page
538 *
539 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
540 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
541 * mechananism between PageLocked pages and PageWriteback pages is shared.
542 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
543 *
Nick Piggin8413ac92008-10-18 20:26:59 -0700544 * The mb is necessary to enforce ordering between the clear_bit and the read
545 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800547void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548{
Nick Piggin8413ac92008-10-18 20:26:59 -0700549 VM_BUG_ON(!PageLocked(page));
550 clear_bit_unlock(PG_locked, &page->flags);
551 smp_mb__after_clear_bit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 wake_up_page(page, PG_locked);
553}
554EXPORT_SYMBOL(unlock_page);
555
Randy Dunlap485bb992006-06-23 02:03:49 -0700556/**
557 * end_page_writeback - end writeback against a page
558 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 */
560void end_page_writeback(struct page *page)
561{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700562 if (TestClearPageReclaim(page))
563 rotate_reclaimable_page(page);
564
565 if (!test_clear_page_writeback(page))
566 BUG();
567
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 smp_mb__after_clear_bit();
569 wake_up_page(page, PG_writeback);
570}
571EXPORT_SYMBOL(end_page_writeback);
572
Randy Dunlap485bb992006-06-23 02:03:49 -0700573/**
574 * __lock_page - get a lock on the page, assuming we need to sleep to get it
575 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700577 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700578 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
579 * chances are that on the second loop, the block layer's plug list is empty,
580 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
581 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800582void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583{
584 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
585
586 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
587 TASK_UNINTERRUPTIBLE);
588}
589EXPORT_SYMBOL(__lock_page);
590
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800591int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500592{
593 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
594
595 return __wait_on_bit_lock(page_waitqueue(page), &wait,
596 sync_page_killable, TASK_KILLABLE);
597}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300598EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500599
Randy Dunlap76824862008-03-19 17:00:40 -0700600/**
601 * __lock_page_nosync - get a lock on the page, without calling sync_page()
602 * @page: the page to lock
603 *
Nick Piggindb376482006-09-25 23:31:24 -0700604 * Variant of lock_page that does not require the caller to hold a reference
605 * on the page's mapping.
606 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800607void __lock_page_nosync(struct page *page)
Nick Piggindb376482006-09-25 23:31:24 -0700608{
609 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
610 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
611 TASK_UNINTERRUPTIBLE);
612}
613
Randy Dunlap485bb992006-06-23 02:03:49 -0700614/**
615 * find_get_page - find and get a page reference
616 * @mapping: the address_space to search
617 * @offset: the page index
618 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700619 * Is there a pagecache struct page at the given (mapping, offset) tuple?
620 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 */
Nick Piggina60637c2008-07-25 19:45:31 -0700622struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623{
Nick Piggina60637c2008-07-25 19:45:31 -0700624 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 struct page *page;
626
Nick Piggina60637c2008-07-25 19:45:31 -0700627 rcu_read_lock();
628repeat:
629 page = NULL;
630 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
631 if (pagep) {
632 page = radix_tree_deref_slot(pagep);
633 if (unlikely(!page || page == RADIX_TREE_RETRY))
634 goto repeat;
635
636 if (!page_cache_get_speculative(page))
637 goto repeat;
638
639 /*
640 * Has the page moved?
641 * This is part of the lockless pagecache protocol. See
642 * include/linux/pagemap.h for details.
643 */
644 if (unlikely(page != *pagep)) {
645 page_cache_release(page);
646 goto repeat;
647 }
648 }
649 rcu_read_unlock();
650
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 return page;
652}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653EXPORT_SYMBOL(find_get_page);
654
Randy Dunlap485bb992006-06-23 02:03:49 -0700655/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700657 * @mapping: the address_space to search
658 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 *
660 * Locates the desired pagecache page, locks it, increments its reference
661 * count and returns its address.
662 *
663 * Returns zero if the page was not present. find_lock_page() may sleep.
664 */
Nick Piggina60637c2008-07-25 19:45:31 -0700665struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666{
667 struct page *page;
668
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669repeat:
Nick Piggina60637c2008-07-25 19:45:31 -0700670 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 if (page) {
Nick Piggina60637c2008-07-25 19:45:31 -0700672 lock_page(page);
673 /* Has the page been truncated? */
674 if (unlikely(page->mapping != mapping)) {
675 unlock_page(page);
676 page_cache_release(page);
677 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 }
Nick Piggina60637c2008-07-25 19:45:31 -0700679 VM_BUG_ON(page->index != offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 return page;
682}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683EXPORT_SYMBOL(find_lock_page);
684
685/**
686 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700687 * @mapping: the page's address_space
688 * @index: the page's index into the mapping
689 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 *
691 * Locates a page in the pagecache. If the page is not present, a new page
692 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
693 * LRU list. The returned page is locked and has its reference count
694 * incremented.
695 *
696 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
697 * allocation!
698 *
699 * find_or_create_page() returns the desired page's address, or zero on
700 * memory exhaustion.
701 */
702struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700703 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704{
Nick Piggineb2be182007-10-16 01:24:57 -0700705 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706 int err;
707repeat:
708 page = find_lock_page(mapping, index);
709 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700710 page = __page_cache_alloc(gfp_mask);
711 if (!page)
712 return NULL;
Nick Piggin67d58ac2009-01-06 14:40:28 -0800713 /*
714 * We want a regular kernel memory (not highmem or DMA etc)
715 * allocation for the radix tree nodes, but we need to honour
716 * the context-specific requirements the caller has asked for.
717 * GFP_RECLAIM_MASK collects those requirements.
718 */
719 err = add_to_page_cache_lru(page, mapping, index,
720 (gfp_mask & GFP_RECLAIM_MASK));
Nick Piggineb2be182007-10-16 01:24:57 -0700721 if (unlikely(err)) {
722 page_cache_release(page);
723 page = NULL;
724 if (err == -EEXIST)
725 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 return page;
729}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730EXPORT_SYMBOL(find_or_create_page);
731
732/**
733 * find_get_pages - gang pagecache lookup
734 * @mapping: The address_space to search
735 * @start: The starting page index
736 * @nr_pages: The maximum number of pages
737 * @pages: Where the resulting pages are placed
738 *
739 * find_get_pages() will search for and return a group of up to
740 * @nr_pages pages in the mapping. The pages are placed at @pages.
741 * find_get_pages() takes a reference against the returned pages.
742 *
743 * The search returns a group of mapping-contiguous pages with ascending
744 * indexes. There may be holes in the indices due to not-present pages.
745 *
746 * find_get_pages() returns the number of pages which were found.
747 */
748unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
749 unsigned int nr_pages, struct page **pages)
750{
751 unsigned int i;
752 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700753 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754
Nick Piggina60637c2008-07-25 19:45:31 -0700755 rcu_read_lock();
756restart:
757 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
758 (void ***)pages, start, nr_pages);
759 ret = 0;
760 for (i = 0; i < nr_found; i++) {
761 struct page *page;
762repeat:
763 page = radix_tree_deref_slot((void **)pages[i]);
764 if (unlikely(!page))
765 continue;
766 /*
767 * this can only trigger if nr_found == 1, making livelock
768 * a non issue.
769 */
770 if (unlikely(page == RADIX_TREE_RETRY))
771 goto restart;
772
773 if (!page_cache_get_speculative(page))
774 goto repeat;
775
776 /* Has the page moved? */
777 if (unlikely(page != *((void **)pages[i]))) {
778 page_cache_release(page);
779 goto repeat;
780 }
781
782 pages[ret] = page;
783 ret++;
784 }
785 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 return ret;
787}
788
Jens Axboeebf43502006-04-27 08:46:01 +0200789/**
790 * find_get_pages_contig - gang contiguous pagecache lookup
791 * @mapping: The address_space to search
792 * @index: The starting page index
793 * @nr_pages: The maximum number of pages
794 * @pages: Where the resulting pages are placed
795 *
796 * find_get_pages_contig() works exactly like find_get_pages(), except
797 * that the returned number of pages are guaranteed to be contiguous.
798 *
799 * find_get_pages_contig() returns the number of pages which were found.
800 */
801unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
802 unsigned int nr_pages, struct page **pages)
803{
804 unsigned int i;
805 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700806 unsigned int nr_found;
Jens Axboeebf43502006-04-27 08:46:01 +0200807
Nick Piggina60637c2008-07-25 19:45:31 -0700808 rcu_read_lock();
809restart:
810 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
811 (void ***)pages, index, nr_pages);
812 ret = 0;
813 for (i = 0; i < nr_found; i++) {
814 struct page *page;
815repeat:
816 page = radix_tree_deref_slot((void **)pages[i]);
817 if (unlikely(!page))
818 continue;
819 /*
820 * this can only trigger if nr_found == 1, making livelock
821 * a non issue.
822 */
823 if (unlikely(page == RADIX_TREE_RETRY))
824 goto restart;
825
826 if (page->mapping == NULL || page->index != index)
Jens Axboeebf43502006-04-27 08:46:01 +0200827 break;
828
Nick Piggina60637c2008-07-25 19:45:31 -0700829 if (!page_cache_get_speculative(page))
830 goto repeat;
831
832 /* Has the page moved? */
833 if (unlikely(page != *((void **)pages[i]))) {
834 page_cache_release(page);
835 goto repeat;
836 }
837
838 pages[ret] = page;
839 ret++;
Jens Axboeebf43502006-04-27 08:46:01 +0200840 index++;
841 }
Nick Piggina60637c2008-07-25 19:45:31 -0700842 rcu_read_unlock();
843 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +0200844}
David Howellsef71c152007-05-09 02:33:44 -0700845EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200846
Randy Dunlap485bb992006-06-23 02:03:49 -0700847/**
848 * find_get_pages_tag - find and return pages that match @tag
849 * @mapping: the address_space to search
850 * @index: the starting page index
851 * @tag: the tag index
852 * @nr_pages: the maximum number of pages
853 * @pages: where the resulting pages are placed
854 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700856 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 */
858unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
859 int tag, unsigned int nr_pages, struct page **pages)
860{
861 unsigned int i;
862 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700863 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864
Nick Piggina60637c2008-07-25 19:45:31 -0700865 rcu_read_lock();
866restart:
867 nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
868 (void ***)pages, *index, nr_pages, tag);
869 ret = 0;
870 for (i = 0; i < nr_found; i++) {
871 struct page *page;
872repeat:
873 page = radix_tree_deref_slot((void **)pages[i]);
874 if (unlikely(!page))
875 continue;
876 /*
877 * this can only trigger if nr_found == 1, making livelock
878 * a non issue.
879 */
880 if (unlikely(page == RADIX_TREE_RETRY))
881 goto restart;
882
883 if (!page_cache_get_speculative(page))
884 goto repeat;
885
886 /* Has the page moved? */
887 if (unlikely(page != *((void **)pages[i]))) {
888 page_cache_release(page);
889 goto repeat;
890 }
891
892 pages[ret] = page;
893 ret++;
894 }
895 rcu_read_unlock();
896
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 if (ret)
898 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -0700899
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 return ret;
901}
David Howellsef71c152007-05-09 02:33:44 -0700902EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
Randy Dunlap485bb992006-06-23 02:03:49 -0700904/**
905 * grab_cache_page_nowait - returns locked page at given index in given cache
906 * @mapping: target address_space
907 * @index: the page index
908 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800909 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 * This is intended for speculative data generators, where the data can
911 * be regenerated if the page couldn't be grabbed. This routine should
912 * be safe to call while holding the lock for another page.
913 *
914 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
915 * and deadlock against the caller's locked page.
916 */
917struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700918grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700919{
920 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
922 if (page) {
Nick Piggin529ae9a2008-08-02 12:01:03 +0200923 if (trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924 return page;
925 page_cache_release(page);
926 return NULL;
927 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700928 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
Nick Piggin67d58ac2009-01-06 14:40:28 -0800929 if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 page_cache_release(page);
931 page = NULL;
932 }
933 return page;
934}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935EXPORT_SYMBOL(grab_cache_page_nowait);
936
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700937/*
938 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
939 * a _large_ part of the i/o request. Imagine the worst scenario:
940 *
941 * ---R__________________________________________B__________
942 * ^ reading here ^ bad block(assume 4k)
943 *
944 * read(R) => miss => readahead(R...B) => media error => frustrating retries
945 * => failing the whole request => read(R) => read(R+1) =>
946 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
947 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
948 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
949 *
950 * It is going insane. Fix it by quickly scaling down the readahead size.
951 */
952static void shrink_readahead_size_eio(struct file *filp,
953 struct file_ra_state *ra)
954{
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700955 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700956}
957
Randy Dunlap485bb992006-06-23 02:03:49 -0700958/**
Christoph Hellwig36e78912008-02-08 04:21:24 -0800959 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -0700960 * @filp: the file to read
961 * @ppos: current file position
962 * @desc: read_descriptor
963 * @actor: read method
964 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700966 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 *
968 * This is really ugly. But the goto's actually try to clarify some
969 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 */
Christoph Hellwig36e78912008-02-08 04:21:24 -0800971static void do_generic_file_read(struct file *filp, loff_t *ppos,
972 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973{
Christoph Hellwig36e78912008-02-08 04:21:24 -0800974 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -0800976 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700977 pgoff_t index;
978 pgoff_t last_index;
979 pgoff_t prev_index;
980 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -0700981 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -0700985 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
986 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
988 offset = *ppos & ~PAGE_CACHE_MASK;
989
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 for (;;) {
991 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700992 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -0700993 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994 unsigned long nr, ret;
995
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997find_page:
998 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -0700999 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001000 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001001 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001002 index, last_index - index);
1003 page = find_get_page(mapping, index);
1004 if (unlikely(page == NULL))
1005 goto no_cached_page;
1006 }
1007 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001008 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001009 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001010 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001012 if (!PageUptodate(page)) {
1013 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1014 !mapping->a_ops->is_partially_uptodate)
1015 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001016 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001017 goto page_not_up_to_date;
1018 if (!mapping->a_ops->is_partially_uptodate(page,
1019 desc, offset))
1020 goto page_not_up_to_date_locked;
1021 unlock_page(page);
1022 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001024 /*
1025 * i_size must be checked after we know the page is Uptodate.
1026 *
1027 * Checking i_size after the check allows us to calculate
1028 * the correct value for "nr", which means the zero-filled
1029 * part of the page is not copied back to userspace (unless
1030 * another truncate extends the file - this is desired though).
1031 */
1032
1033 isize = i_size_read(inode);
1034 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1035 if (unlikely(!isize || index > end_index)) {
1036 page_cache_release(page);
1037 goto out;
1038 }
1039
1040 /* nr is the maximum number of bytes to copy from this page */
1041 nr = PAGE_CACHE_SIZE;
1042 if (index == end_index) {
1043 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1044 if (nr <= offset) {
1045 page_cache_release(page);
1046 goto out;
1047 }
1048 }
1049 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050
1051 /* If users can be writing to this page using arbitrary
1052 * virtual addresses, take care about potential aliasing
1053 * before reading the page on the kernel side.
1054 */
1055 if (mapping_writably_mapped(mapping))
1056 flush_dcache_page(page);
1057
1058 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001059 * When a sequential read accesses a page several times,
1060 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 */
Jan Karaec0f1632007-05-06 14:49:25 -07001062 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 mark_page_accessed(page);
1064 prev_index = index;
1065
1066 /*
1067 * Ok, we have the page, and it's up-to-date, so
1068 * now we can copy it to user space...
1069 *
1070 * The actor routine returns how many bytes were actually used..
1071 * NOTE! This may not be the same as how much of a user buffer
1072 * we filled up (we may be padding etc), so we can only update
1073 * "pos" here (the actor routine has to update the user buffer
1074 * pointers and the remaining count).
1075 */
1076 ret = actor(desc, page, offset, nr);
1077 offset += ret;
1078 index += offset >> PAGE_CACHE_SHIFT;
1079 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001080 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081
1082 page_cache_release(page);
1083 if (ret == nr && desc->count)
1084 continue;
1085 goto out;
1086
1087page_not_up_to_date:
1088 /* Get exclusive access to the page ... */
Oleg Nesterov85462322008-06-08 21:20:43 +04001089 error = lock_page_killable(page);
1090 if (unlikely(error))
1091 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001093page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001094 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 if (!page->mapping) {
1096 unlock_page(page);
1097 page_cache_release(page);
1098 continue;
1099 }
1100
1101 /* Did somebody else fill it already? */
1102 if (PageUptodate(page)) {
1103 unlock_page(page);
1104 goto page_ok;
1105 }
1106
1107readpage:
1108 /* Start the actual read. The read will unlock the page. */
1109 error = mapping->a_ops->readpage(filp, page);
1110
Zach Brown994fc28c2005-12-15 14:28:17 -08001111 if (unlikely(error)) {
1112 if (error == AOP_TRUNCATED_PAGE) {
1113 page_cache_release(page);
1114 goto find_page;
1115 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001117 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001118
1119 if (!PageUptodate(page)) {
Oleg Nesterov85462322008-06-08 21:20:43 +04001120 error = lock_page_killable(page);
1121 if (unlikely(error))
1122 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 if (!PageUptodate(page)) {
1124 if (page->mapping == NULL) {
1125 /*
Christoph Hellwig2ecdc822010-01-26 17:27:20 +01001126 * invalidate_mapping_pages got it
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 */
1128 unlock_page(page);
1129 page_cache_release(page);
1130 goto find_page;
1131 }
1132 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001133 shrink_readahead_size_eio(filp, ra);
Oleg Nesterov85462322008-06-08 21:20:43 +04001134 error = -EIO;
1135 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001136 }
1137 unlock_page(page);
1138 }
1139
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 goto page_ok;
1141
1142readpage_error:
1143 /* UHHUH! A synchronous read error occurred. Report it */
1144 desc->error = error;
1145 page_cache_release(page);
1146 goto out;
1147
1148no_cached_page:
1149 /*
1150 * Ok, it wasn't cached, so we need to create a new
1151 * page..
1152 */
Nick Piggineb2be182007-10-16 01:24:57 -07001153 page = page_cache_alloc_cold(mapping);
1154 if (!page) {
1155 desc->error = -ENOMEM;
1156 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157 }
Nick Piggineb2be182007-10-16 01:24:57 -07001158 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 index, GFP_KERNEL);
1160 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001161 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 if (error == -EEXIST)
1163 goto find_page;
1164 desc->error = error;
1165 goto out;
1166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167 goto readpage;
1168 }
1169
1170out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001171 ra->prev_pos = prev_index;
1172 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1173 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001175 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Krishna Kumar0c6aa262008-10-15 22:01:13 -07001176 file_accessed(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178
1179int file_read_actor(read_descriptor_t *desc, struct page *page,
1180 unsigned long offset, unsigned long size)
1181{
1182 char *kaddr;
1183 unsigned long left, count = desc->count;
1184
1185 if (size > count)
1186 size = count;
1187
1188 /*
1189 * Faults on the destination of a read are common, so do it before
1190 * taking the kmap.
1191 */
1192 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1193 kaddr = kmap_atomic(page, KM_USER0);
1194 left = __copy_to_user_inatomic(desc->arg.buf,
1195 kaddr + offset, size);
1196 kunmap_atomic(kaddr, KM_USER0);
1197 if (left == 0)
1198 goto success;
1199 }
1200
1201 /* Do it the slow way */
1202 kaddr = kmap(page);
1203 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1204 kunmap(page);
1205
1206 if (left) {
1207 size -= left;
1208 desc->error = -EFAULT;
1209 }
1210success:
1211 desc->count = count - size;
1212 desc->written += size;
1213 desc->arg.buf += size;
1214 return size;
1215}
1216
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001217/*
1218 * Performs necessary checks before doing a write
1219 * @iov: io vector request
1220 * @nr_segs: number of segments in the iovec
1221 * @count: number of bytes to write
1222 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1223 *
1224 * Adjust number of segments and amount of bytes to write (nr_segs should be
1225 * properly initialized first). Returns appropriate error code that caller
1226 * should return or zero in case that write should be allowed.
1227 */
1228int generic_segment_checks(const struct iovec *iov,
1229 unsigned long *nr_segs, size_t *count, int access_flags)
1230{
1231 unsigned long seg;
1232 size_t cnt = 0;
1233 for (seg = 0; seg < *nr_segs; seg++) {
1234 const struct iovec *iv = &iov[seg];
1235
1236 /*
1237 * If any segment has a negative length, or the cumulative
1238 * length ever wraps negative then return -EINVAL.
1239 */
1240 cnt += iv->iov_len;
1241 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1242 return -EINVAL;
1243 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1244 continue;
1245 if (seg == 0)
1246 return -EFAULT;
1247 *nr_segs = seg;
1248 cnt -= iv->iov_len; /* This segment is no good */
1249 break;
1250 }
1251 *count = cnt;
1252 return 0;
1253}
1254EXPORT_SYMBOL(generic_segment_checks);
1255
Randy Dunlap485bb992006-06-23 02:03:49 -07001256/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001257 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001258 * @iocb: kernel I/O control block
1259 * @iov: io vector request
1260 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001261 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001262 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 * This is the "read()" routine for all filesystems
1264 * that can use the page cache directly.
1265 */
1266ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001267generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1268 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269{
1270 struct file *filp = iocb->ki_filp;
1271 ssize_t retval;
1272 unsigned long seg;
1273 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001274 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275
1276 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001277 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1278 if (retval)
1279 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
1281 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1282 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001283 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284 struct address_space *mapping;
1285 struct inode *inode;
1286
1287 mapping = filp->f_mapping;
1288 inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 if (!count)
1290 goto out; /* skip atime */
1291 size = i_size_read(inode);
1292 if (pos < size) {
Nick Piggin48b47c52009-01-06 14:40:22 -08001293 retval = filemap_write_and_wait_range(mapping, pos,
1294 pos + iov_length(iov, nr_segs) - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07001295 if (!retval) {
1296 retval = mapping->a_ops->direct_IO(READ, iocb,
1297 iov, pos, nr_segs);
1298 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 if (retval > 0)
1300 *ppos = pos + retval;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001301 if (retval) {
1302 file_accessed(filp);
1303 goto out;
1304 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001305 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306 }
1307
Hugh Dickins11fa9772008-07-23 21:27:34 -07001308 for (seg = 0; seg < nr_segs; seg++) {
1309 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310
Hugh Dickins11fa9772008-07-23 21:27:34 -07001311 desc.written = 0;
1312 desc.arg.buf = iov[seg].iov_base;
1313 desc.count = iov[seg].iov_len;
1314 if (desc.count == 0)
1315 continue;
1316 desc.error = 0;
1317 do_generic_file_read(filp, ppos, &desc, file_read_actor);
1318 retval += desc.written;
1319 if (desc.error) {
1320 retval = retval ?: desc.error;
1321 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 }
Hugh Dickins11fa9772008-07-23 21:27:34 -07001323 if (desc.count > 0)
1324 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 }
1326out:
1327 return retval;
1328}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329EXPORT_SYMBOL(generic_file_aio_read);
1330
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331static ssize_t
1332do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001333 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334{
1335 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1336 return -EINVAL;
1337
Wu Fengguangf7e839d2009-06-16 15:31:20 -07001338 force_page_cache_readahead(mapping, filp, index, nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 return 0;
1340}
1341
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001342SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343{
1344 ssize_t ret;
1345 struct file *file;
1346
1347 ret = -EBADF;
1348 file = fget(fd);
1349 if (file) {
1350 if (file->f_mode & FMODE_READ) {
1351 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001352 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1353 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 unsigned long len = end - start + 1;
1355 ret = do_readahead(mapping, file, start, len);
1356 }
1357 fput(file);
1358 }
1359 return ret;
1360}
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001361#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1362asmlinkage long SyS_readahead(long fd, loff_t offset, long count)
1363{
1364 return SYSC_readahead((int) fd, offset, (size_t) count);
1365}
1366SYSCALL_ALIAS(sys_readahead, SyS_readahead);
1367#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368
1369#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001370/**
1371 * page_cache_read - adds requested page to the page cache if not already there
1372 * @file: file to read
1373 * @offset: page index
1374 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375 * This adds the requested page to the page cache if it isn't already there,
1376 * and schedules an I/O to read in its contents from disk.
1377 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001378static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379{
1380 struct address_space *mapping = file->f_mapping;
1381 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001382 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383
Zach Brown994fc28c2005-12-15 14:28:17 -08001384 do {
1385 page = page_cache_alloc_cold(mapping);
1386 if (!page)
1387 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388
Zach Brown994fc28c2005-12-15 14:28:17 -08001389 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1390 if (ret == 0)
1391 ret = mapping->a_ops->readpage(file, page);
1392 else if (ret == -EEXIST)
1393 ret = 0; /* losing race to add is OK */
1394
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396
Zach Brown994fc28c2005-12-15 14:28:17 -08001397 } while (ret == AOP_TRUNCATED_PAGE);
1398
1399 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400}
1401
1402#define MMAP_LOTSAMISS (100)
1403
Linus Torvaldsef00e082009-06-16 15:31:25 -07001404/*
1405 * Synchronous readahead happens when we don't even find
1406 * a page in the page cache at all.
1407 */
1408static void do_sync_mmap_readahead(struct vm_area_struct *vma,
1409 struct file_ra_state *ra,
1410 struct file *file,
1411 pgoff_t offset)
1412{
1413 unsigned long ra_pages;
1414 struct address_space *mapping = file->f_mapping;
1415
1416 /* If we don't want any read-ahead, don't bother */
1417 if (VM_RandomReadHint(vma))
1418 return;
1419
Wu Fengguang70ac23c2009-06-16 15:31:28 -07001420 if (VM_SequentialReadHint(vma) ||
1421 offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) {
Wu Fengguang7ffc59b2009-06-16 15:31:38 -07001422 page_cache_sync_readahead(mapping, ra, file, offset,
1423 ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001424 return;
1425 }
1426
1427 if (ra->mmap_miss < INT_MAX)
1428 ra->mmap_miss++;
1429
1430 /*
1431 * Do we miss much more than hit in this file? If so,
1432 * stop bothering with read-ahead. It will only hurt.
1433 */
1434 if (ra->mmap_miss > MMAP_LOTSAMISS)
1435 return;
1436
Wu Fengguangd30a1102009-06-16 15:31:30 -07001437 /*
1438 * mmap read-around
1439 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001440 ra_pages = max_sane_readahead(ra->ra_pages);
1441 if (ra_pages) {
Wu Fengguangd30a1102009-06-16 15:31:30 -07001442 ra->start = max_t(long, 0, offset - ra_pages/2);
1443 ra->size = ra_pages;
1444 ra->async_size = 0;
1445 ra_submit(ra, mapping, file);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001446 }
1447}
1448
1449/*
1450 * Asynchronous readahead happens when we find the page and PG_readahead,
1451 * so we want to possibly extend the readahead further..
1452 */
1453static void do_async_mmap_readahead(struct vm_area_struct *vma,
1454 struct file_ra_state *ra,
1455 struct file *file,
1456 struct page *page,
1457 pgoff_t offset)
1458{
1459 struct address_space *mapping = file->f_mapping;
1460
1461 /* If we don't want any read-ahead, don't bother */
1462 if (VM_RandomReadHint(vma))
1463 return;
1464 if (ra->mmap_miss > 0)
1465 ra->mmap_miss--;
1466 if (PageReadahead(page))
Wu Fengguang2fad6f52009-06-16 15:31:29 -07001467 page_cache_async_readahead(mapping, ra, file,
1468 page, offset, ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001469}
1470
Randy Dunlap485bb992006-06-23 02:03:49 -07001471/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001472 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001473 * @vma: vma in which the fault was taken
1474 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001475 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001476 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 * mapped memory region to read in file data during a page fault.
1478 *
1479 * The goto's are kind of ugly, but this streamlines the normal case of having
1480 * it in the page cache, and handles the special cases reasonably without
1481 * having a lot of duplicated code.
1482 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001483int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484{
1485 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001486 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 struct address_space *mapping = file->f_mapping;
1488 struct file_ra_state *ra = &file->f_ra;
1489 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001490 pgoff_t offset = vmf->pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001492 pgoff_t size;
Nick Piggin83c54072007-07-19 01:47:05 -07001493 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001496 if (offset >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001497 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 * Do we have something in the page cache already?
1501 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001502 page = find_get_page(mapping, offset);
1503 if (likely(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07001505 * We found the page, so try async readahead before
1506 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001508 do_async_mmap_readahead(vma, ra, file, page, offset);
1509 lock_page(page);
1510
1511 /* Did it get truncated? */
1512 if (unlikely(page->mapping != mapping)) {
1513 unlock_page(page);
1514 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 goto no_cached_page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516 }
Linus Torvaldsef00e082009-06-16 15:31:25 -07001517 } else {
1518 /* No page in the page cache at all */
1519 do_sync_mmap_readahead(vma, ra, file, offset);
1520 count_vm_event(PGMAJFAULT);
1521 ret = VM_FAULT_MAJOR;
1522retry_find:
1523 page = find_lock_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 if (!page)
1525 goto no_cached_page;
1526 }
1527
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001529 * We have a locked page in the page cache, now we need to check
1530 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 */
Nick Piggind00806b2007-07-19 01:46:57 -07001532 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 goto page_not_uptodate;
1534
Linus Torvaldsef00e082009-06-16 15:31:25 -07001535 /*
1536 * Found the page and have a reference on it.
1537 * We must recheck i_size under page lock.
1538 */
Nick Piggind00806b2007-07-19 01:46:57 -07001539 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001540 if (unlikely(offset >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001541 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001542 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001543 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001544 }
1545
Linus Torvaldsef00e082009-06-16 15:31:25 -07001546 ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001547 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001548 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550no_cached_page:
1551 /*
1552 * We're only likely to ever get here if MADV_RANDOM is in
1553 * effect.
1554 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001555 error = page_cache_read(file, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556
1557 /*
1558 * The page we want has now been added to the page cache.
1559 * In the unlikely event that someone removed it in the
1560 * meantime, we'll just come back here and read it again.
1561 */
1562 if (error >= 0)
1563 goto retry_find;
1564
1565 /*
1566 * An error return from page_cache_read can result if the
1567 * system is low on memory, or a problem occurs while trying
1568 * to schedule I/O.
1569 */
1570 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001571 return VM_FAULT_OOM;
1572 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573
1574page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575 /*
1576 * Umm, take care of errors if the page isn't up-to-date.
1577 * Try to re-read it _once_. We do this synchronously,
1578 * because there really aren't any performance issues here
1579 * and we need to check for errors.
1580 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001582 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001583 if (!error) {
1584 wait_on_page_locked(page);
1585 if (!PageUptodate(page))
1586 error = -EIO;
1587 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001589
1590 if (!error || error == AOP_TRUNCATED_PAGE)
1591 goto retry_find;
1592
1593 /* Things didn't work out. Return zero to tell the mm layer so. */
1594 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001595 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001596}
1597EXPORT_SYMBOL(filemap_fault);
1598
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04001599const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001600 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601};
1602
1603/* This is used for a general mmap of a disk file */
1604
1605int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1606{
1607 struct address_space *mapping = file->f_mapping;
1608
1609 if (!mapping->a_ops->readpage)
1610 return -ENOEXEC;
1611 file_accessed(file);
1612 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001613 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 return 0;
1615}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616
1617/*
1618 * This is for filesystems which do not implement ->writepage.
1619 */
1620int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1621{
1622 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1623 return -EINVAL;
1624 return generic_file_mmap(file, vma);
1625}
1626#else
1627int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1628{
1629 return -ENOSYS;
1630}
1631int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1632{
1633 return -ENOSYS;
1634}
1635#endif /* CONFIG_MMU */
1636
1637EXPORT_SYMBOL(generic_file_mmap);
1638EXPORT_SYMBOL(generic_file_readonly_mmap);
1639
Nick Piggin6fe69002007-05-06 14:49:04 -07001640static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001641 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001643 void *data,
1644 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645{
Nick Piggineb2be182007-10-16 01:24:57 -07001646 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 int err;
1648repeat:
1649 page = find_get_page(mapping, index);
1650 if (!page) {
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001651 page = __page_cache_alloc(gfp | __GFP_COLD);
Nick Piggineb2be182007-10-16 01:24:57 -07001652 if (!page)
1653 return ERR_PTR(-ENOMEM);
1654 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1655 if (unlikely(err)) {
1656 page_cache_release(page);
1657 if (err == -EEXIST)
1658 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 return ERR_PTR(err);
1661 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 err = filler(data, page);
1663 if (err < 0) {
1664 page_cache_release(page);
1665 page = ERR_PTR(err);
1666 }
1667 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 return page;
1669}
1670
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001671static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001672 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001674 void *data,
1675 gfp_t gfp)
1676
Linus Torvalds1da177e2005-04-16 15:20:36 -07001677{
1678 struct page *page;
1679 int err;
1680
1681retry:
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001682 page = __read_cache_page(mapping, index, filler, data, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001684 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 if (PageUptodate(page))
1686 goto out;
1687
1688 lock_page(page);
1689 if (!page->mapping) {
1690 unlock_page(page);
1691 page_cache_release(page);
1692 goto retry;
1693 }
1694 if (PageUptodate(page)) {
1695 unlock_page(page);
1696 goto out;
1697 }
1698 err = filler(data, page);
1699 if (err < 0) {
1700 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001701 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 }
David Howellsc855ff32007-05-09 13:42:20 +01001703out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001704 mark_page_accessed(page);
1705 return page;
1706}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001707
1708/**
1709 * read_cache_page_async - read into page cache, fill it if needed
1710 * @mapping: the page's address_space
1711 * @index: the page index
1712 * @filler: function to perform the read
1713 * @data: destination for read data
1714 *
1715 * Same as read_cache_page, but don't wait for page to become unlocked
1716 * after submitting it to the filler.
1717 *
1718 * Read into the page cache. If a page already exists, and PageUptodate() is
1719 * not set, try to fill the page but don't wait for it to become unlocked.
1720 *
1721 * If the page does not get brought uptodate, return -EIO.
1722 */
1723struct page *read_cache_page_async(struct address_space *mapping,
1724 pgoff_t index,
1725 int (*filler)(void *,struct page*),
1726 void *data)
1727{
1728 return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
1729}
Nick Piggin6fe69002007-05-06 14:49:04 -07001730EXPORT_SYMBOL(read_cache_page_async);
1731
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001732static struct page *wait_on_page_read(struct page *page)
1733{
1734 if (!IS_ERR(page)) {
1735 wait_on_page_locked(page);
1736 if (!PageUptodate(page)) {
1737 page_cache_release(page);
1738 page = ERR_PTR(-EIO);
1739 }
1740 }
1741 return page;
1742}
1743
1744/**
1745 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
1746 * @mapping: the page's address_space
1747 * @index: the page index
1748 * @gfp: the page allocator flags to use if allocating
1749 *
1750 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
1751 * any new page allocations done using the specified allocation flags. Note
1752 * that the Radix tree operations will still use GFP_KERNEL, so you can't
1753 * expect to do this atomically or anything like that - but you can pass in
1754 * other page requirements.
1755 *
1756 * If the page does not get brought uptodate, return -EIO.
1757 */
1758struct page *read_cache_page_gfp(struct address_space *mapping,
1759 pgoff_t index,
1760 gfp_t gfp)
1761{
1762 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
1763
1764 return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp));
1765}
1766EXPORT_SYMBOL(read_cache_page_gfp);
1767
Nick Piggin6fe69002007-05-06 14:49:04 -07001768/**
1769 * read_cache_page - read into page cache, fill it if needed
1770 * @mapping: the page's address_space
1771 * @index: the page index
1772 * @filler: function to perform the read
1773 * @data: destination for read data
1774 *
1775 * Read into the page cache. If a page already exists, and PageUptodate() is
1776 * not set, try to fill the page then wait for it to become unlocked.
1777 *
1778 * If the page does not get brought uptodate, return -EIO.
1779 */
1780struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001781 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001782 int (*filler)(void *,struct page*),
1783 void *data)
1784{
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001785 return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787EXPORT_SYMBOL(read_cache_page);
1788
1789/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 * The logic we want is
1791 *
1792 * if suid or (sgid and xgrp)
1793 * remove privs
1794 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001795int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796{
1797 mode_t mode = dentry->d_inode->i_mode;
1798 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001799
1800 /* suid always must be killed */
1801 if (unlikely(mode & S_ISUID))
1802 kill = ATTR_KILL_SUID;
1803
1804 /*
1805 * sgid without any exec bits is just a mandatory locking mark; leave
1806 * it alone. If some exec bits are set, it's a real sgid; kill it.
1807 */
1808 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1809 kill |= ATTR_KILL_SGID;
1810
Dmitri Monakhov7f5ff762008-12-01 14:34:56 -08001811 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
Jens Axboe01de85e2006-10-17 19:50:36 +02001812 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813
Jens Axboe01de85e2006-10-17 19:50:36 +02001814 return 0;
1815}
Mark Fashehd23a1472006-10-17 17:05:18 -07001816EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001817
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +02001818static int __remove_suid(struct dentry *dentry, int kill)
Jens Axboe01de85e2006-10-17 19:50:36 +02001819{
1820 struct iattr newattrs;
1821
1822 newattrs.ia_valid = ATTR_FORCE | kill;
1823 return notify_change(dentry, &newattrs);
1824}
1825
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001826int file_remove_suid(struct file *file)
Jens Axboe01de85e2006-10-17 19:50:36 +02001827{
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001828 struct dentry *dentry = file->f_path.dentry;
Serge E. Hallynb5376772007-10-16 23:31:36 -07001829 int killsuid = should_remove_suid(dentry);
1830 int killpriv = security_inode_need_killpriv(dentry);
1831 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001832
Serge E. Hallynb5376772007-10-16 23:31:36 -07001833 if (killpriv < 0)
1834 return killpriv;
1835 if (killpriv)
1836 error = security_inode_killpriv(dentry);
1837 if (!error && killsuid)
1838 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001839
Serge E. Hallynb5376772007-10-16 23:31:36 -07001840 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841}
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001842EXPORT_SYMBOL(file_remove_suid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843
Nick Piggin2f718ff2007-10-16 01:24:59 -07001844static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001845 const struct iovec *iov, size_t base, size_t bytes)
1846{
Ingo Molnarf1800532009-03-02 11:00:57 +01001847 size_t copied = 0, left = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848
1849 while (bytes) {
1850 char __user *buf = iov->iov_base + base;
1851 int copy = min(bytes, iov->iov_len - base);
1852
1853 base = 0;
Ingo Molnarf1800532009-03-02 11:00:57 +01001854 left = __copy_from_user_inatomic(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855 copied += copy;
1856 bytes -= copy;
1857 vaddr += copy;
1858 iov++;
1859
NeilBrown01408c42006-06-25 05:47:58 -07001860 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862 }
1863 return copied - left;
1864}
1865
1866/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001867 * Copy as much as we can into the page and return the number of bytes which
André Goddard Rosaaf901ca2009-11-14 13:09:05 -02001868 * were successfully copied. If a fault is encountered then return the number of
Nick Piggin2f718ff2007-10-16 01:24:59 -07001869 * bytes which were copied.
1870 */
1871size_t iov_iter_copy_from_user_atomic(struct page *page,
1872 struct iov_iter *i, unsigned long offset, size_t bytes)
1873{
1874 char *kaddr;
1875 size_t copied;
1876
1877 BUG_ON(!in_atomic());
1878 kaddr = kmap_atomic(page, KM_USER0);
1879 if (likely(i->nr_segs == 1)) {
1880 int left;
1881 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001882 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001883 copied = bytes - left;
1884 } else {
1885 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1886 i->iov, i->iov_offset, bytes);
1887 }
1888 kunmap_atomic(kaddr, KM_USER0);
1889
1890 return copied;
1891}
Nick Piggin89e10782007-10-16 01:25:07 -07001892EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001893
1894/*
1895 * This has the same sideeffects and return value as
1896 * iov_iter_copy_from_user_atomic().
1897 * The difference is that it attempts to resolve faults.
1898 * Page must not be locked.
1899 */
1900size_t iov_iter_copy_from_user(struct page *page,
1901 struct iov_iter *i, unsigned long offset, size_t bytes)
1902{
1903 char *kaddr;
1904 size_t copied;
1905
1906 kaddr = kmap(page);
1907 if (likely(i->nr_segs == 1)) {
1908 int left;
1909 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001910 left = __copy_from_user(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001911 copied = bytes - left;
1912 } else {
1913 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1914 i->iov, i->iov_offset, bytes);
1915 }
1916 kunmap(page);
1917 return copied;
1918}
Nick Piggin89e10782007-10-16 01:25:07 -07001919EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001920
Nick Pigginf7009262008-03-10 11:43:59 -07001921void iov_iter_advance(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001922{
Nick Pigginf7009262008-03-10 11:43:59 -07001923 BUG_ON(i->count < bytes);
1924
Nick Piggin2f718ff2007-10-16 01:24:59 -07001925 if (likely(i->nr_segs == 1)) {
1926 i->iov_offset += bytes;
Nick Pigginf7009262008-03-10 11:43:59 -07001927 i->count -= bytes;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001928 } else {
1929 const struct iovec *iov = i->iov;
1930 size_t base = i->iov_offset;
1931
Nick Piggin124d3b72008-02-02 15:01:17 +01001932 /*
1933 * The !iov->iov_len check ensures we skip over unlikely
Nick Pigginf7009262008-03-10 11:43:59 -07001934 * zero-length segments (without overruning the iovec).
Nick Piggin124d3b72008-02-02 15:01:17 +01001935 */
Linus Torvalds94ad3742008-07-30 14:45:12 -07001936 while (bytes || unlikely(i->count && !iov->iov_len)) {
Nick Pigginf7009262008-03-10 11:43:59 -07001937 int copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001938
Nick Pigginf7009262008-03-10 11:43:59 -07001939 copy = min(bytes, iov->iov_len - base);
1940 BUG_ON(!i->count || i->count < copy);
1941 i->count -= copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001942 bytes -= copy;
1943 base += copy;
1944 if (iov->iov_len == base) {
1945 iov++;
1946 base = 0;
1947 }
1948 }
1949 i->iov = iov;
1950 i->iov_offset = base;
1951 }
1952}
Nick Piggin89e10782007-10-16 01:25:07 -07001953EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001954
Nick Pigginafddba42007-10-16 01:25:01 -07001955/*
1956 * Fault in the first iovec of the given iov_iter, to a maximum length
1957 * of bytes. Returns 0 on success, or non-zero if the memory could not be
1958 * accessed (ie. because it is an invalid address).
1959 *
1960 * writev-intensive code may want this to prefault several iovecs -- that
1961 * would be possible (callers must not rely on the fact that _only_ the
1962 * first iovec will be faulted with the current implementation).
1963 */
1964int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001965{
Nick Piggin2f718ff2007-10-16 01:24:59 -07001966 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07001967 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
1968 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001969}
Nick Piggin89e10782007-10-16 01:25:07 -07001970EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001971
1972/*
1973 * Return the count of just the current iov_iter segment.
1974 */
1975size_t iov_iter_single_seg_count(struct iov_iter *i)
1976{
1977 const struct iovec *iov = i->iov;
1978 if (i->nr_segs == 1)
1979 return i->count;
1980 else
1981 return min(i->count, iov->iov_len - i->iov_offset);
1982}
Nick Piggin89e10782007-10-16 01:25:07 -07001983EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001984
1985/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 * Performs necessary checks before doing a write
1987 *
Randy Dunlap485bb992006-06-23 02:03:49 -07001988 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001989 * Returns appropriate error code that caller should return or
1990 * zero in case that write should be allowed.
1991 */
1992inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
1993{
1994 struct inode *inode = file->f_mapping->host;
Jiri Slaby59e99e52010-03-05 13:41:44 -08001995 unsigned long limit = rlimit(RLIMIT_FSIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996
1997 if (unlikely(*pos < 0))
1998 return -EINVAL;
1999
Linus Torvalds1da177e2005-04-16 15:20:36 -07002000 if (!isblk) {
2001 /* FIXME: this is for backwards compatibility with 2.4 */
2002 if (file->f_flags & O_APPEND)
2003 *pos = i_size_read(inode);
2004
2005 if (limit != RLIM_INFINITY) {
2006 if (*pos >= limit) {
2007 send_sig(SIGXFSZ, current, 0);
2008 return -EFBIG;
2009 }
2010 if (*count > limit - (typeof(limit))*pos) {
2011 *count = limit - (typeof(limit))*pos;
2012 }
2013 }
2014 }
2015
2016 /*
2017 * LFS rule
2018 */
2019 if (unlikely(*pos + *count > MAX_NON_LFS &&
2020 !(file->f_flags & O_LARGEFILE))) {
2021 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022 return -EFBIG;
2023 }
2024 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2025 *count = MAX_NON_LFS - (unsigned long)*pos;
2026 }
2027 }
2028
2029 /*
2030 * Are we about to exceed the fs block limit ?
2031 *
2032 * If we have written data it becomes a short write. If we have
2033 * exceeded without writing data we send a signal and return EFBIG.
2034 * Linus frestrict idea will clean these up nicely..
2035 */
2036 if (likely(!isblk)) {
2037 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2038 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 return -EFBIG;
2040 }
2041 /* zero-length writes at ->s_maxbytes are OK */
2042 }
2043
2044 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2045 *count = inode->i_sb->s_maxbytes - *pos;
2046 } else {
David Howells93614012006-09-30 20:45:40 +02002047#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002048 loff_t isize;
2049 if (bdev_read_only(I_BDEV(inode)))
2050 return -EPERM;
2051 isize = i_size_read(inode);
2052 if (*pos >= isize) {
2053 if (*count || *pos > isize)
2054 return -ENOSPC;
2055 }
2056
2057 if (*pos + *count > isize)
2058 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002059#else
2060 return -EPERM;
2061#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062 }
2063 return 0;
2064}
2065EXPORT_SYMBOL(generic_write_checks);
2066
Nick Pigginafddba42007-10-16 01:25:01 -07002067int pagecache_write_begin(struct file *file, struct address_space *mapping,
2068 loff_t pos, unsigned len, unsigned flags,
2069 struct page **pagep, void **fsdata)
2070{
2071 const struct address_space_operations *aops = mapping->a_ops;
2072
Nick Piggin4e02ed42008-10-29 14:00:55 -07002073 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002074 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002075}
2076EXPORT_SYMBOL(pagecache_write_begin);
2077
2078int pagecache_write_end(struct file *file, struct address_space *mapping,
2079 loff_t pos, unsigned len, unsigned copied,
2080 struct page *page, void *fsdata)
2081{
2082 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002083
Nick Piggin4e02ed42008-10-29 14:00:55 -07002084 mark_page_accessed(page);
2085 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002086}
2087EXPORT_SYMBOL(pagecache_write_end);
2088
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089ssize_t
2090generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2091 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2092 size_t count, size_t ocount)
2093{
2094 struct file *file = iocb->ki_filp;
2095 struct address_space *mapping = file->f_mapping;
2096 struct inode *inode = mapping->host;
2097 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002098 size_t write_len;
2099 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002100
2101 if (count != ocount)
2102 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2103
Christoph Hellwiga969e902008-07-23 21:27:04 -07002104 write_len = iov_length(iov, *nr_segs);
2105 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002106
Nick Piggin48b47c52009-01-06 14:40:22 -08002107 written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002108 if (written)
2109 goto out;
2110
2111 /*
2112 * After a write we want buffered reads to be sure to go to disk to get
2113 * the new data. We invalidate clean cached page from the region we're
2114 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002115 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002116 */
2117 if (mapping->nrpages) {
2118 written = invalidate_inode_pages2_range(mapping,
2119 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002120 /*
2121 * If a page can not be invalidated, return 0 to fall back
2122 * to buffered write.
2123 */
2124 if (written) {
2125 if (written == -EBUSY)
2126 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002127 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002128 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002129 }
2130
2131 written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2132
2133 /*
2134 * Finally, try again to invalidate clean pages which might have been
2135 * cached by non-direct readahead, or faulted in by get_user_pages()
2136 * if the source of the write was an mmap'ed region of the file
2137 * we're writing. Either one is a pretty crazy thing to do,
2138 * so we don't support it 100%. If this invalidation
2139 * fails, tough, the write still worked...
2140 */
2141 if (mapping->nrpages) {
2142 invalidate_inode_pages2_range(mapping,
2143 pos >> PAGE_CACHE_SHIFT, end);
2144 }
2145
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146 if (written > 0) {
2147 loff_t end = pos + written;
2148 if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2149 i_size_write(inode, end);
2150 mark_inode_dirty(inode);
2151 }
2152 *ppos = end;
2153 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002154out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155 return written;
2156}
2157EXPORT_SYMBOL(generic_file_direct_write);
2158
Nick Piggineb2be182007-10-16 01:24:57 -07002159/*
2160 * Find or create a page at the given pagecache position. Return the locked
2161 * page. This function is specifically for buffered writes.
2162 */
Nick Piggin54566b22009-01-04 12:00:53 -08002163struct page *grab_cache_page_write_begin(struct address_space *mapping,
2164 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07002165{
2166 int status;
2167 struct page *page;
Nick Piggin54566b22009-01-04 12:00:53 -08002168 gfp_t gfp_notmask = 0;
2169 if (flags & AOP_FLAG_NOFS)
2170 gfp_notmask = __GFP_FS;
Nick Piggineb2be182007-10-16 01:24:57 -07002171repeat:
2172 page = find_lock_page(mapping, index);
2173 if (likely(page))
2174 return page;
2175
Nick Piggin54566b22009-01-04 12:00:53 -08002176 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002177 if (!page)
2178 return NULL;
Nick Piggin54566b22009-01-04 12:00:53 -08002179 status = add_to_page_cache_lru(page, mapping, index,
2180 GFP_KERNEL & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002181 if (unlikely(status)) {
2182 page_cache_release(page);
2183 if (status == -EEXIST)
2184 goto repeat;
2185 return NULL;
2186 }
2187 return page;
2188}
Nick Piggin54566b22009-01-04 12:00:53 -08002189EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07002190
Nick Pigginafddba42007-10-16 01:25:01 -07002191static ssize_t generic_perform_write(struct file *file,
2192 struct iov_iter *i, loff_t pos)
2193{
2194 struct address_space *mapping = file->f_mapping;
2195 const struct address_space_operations *a_ops = mapping->a_ops;
2196 long status = 0;
2197 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002198 unsigned int flags = 0;
2199
2200 /*
2201 * Copies from kernel address space cannot fail (NFSD is a big user).
2202 */
2203 if (segment_eq(get_fs(), KERNEL_DS))
2204 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002205
2206 do {
2207 struct page *page;
2208 pgoff_t index; /* Pagecache index for current page */
2209 unsigned long offset; /* Offset into pagecache page */
2210 unsigned long bytes; /* Bytes to write to page */
2211 size_t copied; /* Bytes copied from user */
2212 void *fsdata;
2213
2214 offset = (pos & (PAGE_CACHE_SIZE - 1));
2215 index = pos >> PAGE_CACHE_SHIFT;
2216 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2217 iov_iter_count(i));
2218
2219again:
2220
2221 /*
2222 * Bring in the user page that we will copy from _first_.
2223 * Otherwise there's a nasty deadlock on copying from the
2224 * same page as we're writing to, without it being marked
2225 * up-to-date.
2226 *
2227 * Not only is this an optimisation, but it is also required
2228 * to check that the address is actually valid, when atomic
2229 * usercopies are used, below.
2230 */
2231 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2232 status = -EFAULT;
2233 break;
2234 }
2235
Nick Piggin674b8922007-10-16 01:25:03 -07002236 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002237 &page, &fsdata);
2238 if (unlikely(status))
2239 break;
2240
anfei zhou931e80e2010-02-02 13:44:02 -08002241 if (mapping_writably_mapped(mapping))
2242 flush_dcache_page(page);
2243
Nick Pigginafddba42007-10-16 01:25:01 -07002244 pagefault_disable();
2245 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2246 pagefault_enable();
2247 flush_dcache_page(page);
2248
Josef Bacikc8236db2009-07-05 12:08:18 -07002249 mark_page_accessed(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002250 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2251 page, fsdata);
2252 if (unlikely(status < 0))
2253 break;
2254 copied = status;
2255
2256 cond_resched();
2257
Nick Piggin124d3b72008-02-02 15:01:17 +01002258 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002259 if (unlikely(copied == 0)) {
2260 /*
2261 * If we were unable to copy any data at all, we must
2262 * fall back to a single segment length write.
2263 *
2264 * If we didn't fallback here, we could livelock
2265 * because not all segments in the iov can be copied at
2266 * once without a pagefault.
2267 */
2268 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2269 iov_iter_single_seg_count(i));
2270 goto again;
2271 }
Nick Pigginafddba42007-10-16 01:25:01 -07002272 pos += copied;
2273 written += copied;
2274
2275 balance_dirty_pages_ratelimited(mapping);
2276
2277 } while (iov_iter_count(i));
2278
2279 return written ? written : status;
2280}
2281
2282ssize_t
2283generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2284 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2285 size_t count, ssize_t written)
2286{
2287 struct file *file = iocb->ki_filp;
Nick Pigginafddba42007-10-16 01:25:01 -07002288 ssize_t status;
2289 struct iov_iter i;
2290
2291 iov_iter_init(&i, iov, nr_segs, count, written);
Nick Piggin4e02ed42008-10-29 14:00:55 -07002292 status = generic_perform_write(file, &i, pos);
Nick Pigginafddba42007-10-16 01:25:01 -07002293
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002295 written += status;
2296 *ppos = pos + status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002297 }
2298
Linus Torvalds1da177e2005-04-16 15:20:36 -07002299 return written ? written : status;
2300}
2301EXPORT_SYMBOL(generic_file_buffered_write);
2302
Jan Karae4dd9de2009-08-17 18:10:06 +02002303/**
2304 * __generic_file_aio_write - write data to a file
2305 * @iocb: IO state structure (file, offset, etc.)
2306 * @iov: vector with data to write
2307 * @nr_segs: number of segments in the vector
2308 * @ppos: position where to write
2309 *
2310 * This function does all the work needed for actually writing data to a
2311 * file. It does all basic checks, removes SUID from the file, updates
2312 * modification times and calls proper subroutines depending on whether we
2313 * do direct IO or a standard buffered write.
2314 *
2315 * It expects i_mutex to be grabbed unless we work on a block device or similar
2316 * object which does not need locking at all.
2317 *
2318 * This function does *not* take care of syncing data in case of O_SYNC write.
2319 * A caller has to handle it. This is mainly due to the fact that we want to
2320 * avoid syncing under i_mutex.
2321 */
2322ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2323 unsigned long nr_segs, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324{
2325 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002326 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002327 size_t ocount; /* original count */
2328 size_t count; /* after file limit checks */
2329 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002330 loff_t pos;
2331 ssize_t written;
2332 ssize_t err;
2333
2334 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002335 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2336 if (err)
2337 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338
2339 count = ocount;
2340 pos = *ppos;
2341
2342 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2343
2344 /* We can write back this queue in page reclaim */
2345 current->backing_dev_info = mapping->backing_dev_info;
2346 written = 0;
2347
2348 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2349 if (err)
2350 goto out;
2351
2352 if (count == 0)
2353 goto out;
2354
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002355 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356 if (err)
2357 goto out;
2358
Christoph Hellwig870f4812006-01-09 20:52:01 -08002359 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360
2361 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2362 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002363 loff_t endbyte;
2364 ssize_t written_buffered;
2365
2366 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2367 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368 if (written < 0 || written == count)
2369 goto out;
2370 /*
2371 * direct-io write to a hole: fall through to buffered I/O
2372 * for completing the rest of the request.
2373 */
2374 pos += written;
2375 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002376 written_buffered = generic_file_buffered_write(iocb, iov,
2377 nr_segs, pos, ppos, count,
2378 written);
2379 /*
2380 * If generic_file_buffered_write() retuned a synchronous error
2381 * then we want to return the number of bytes which were
2382 * direct-written, or the error code if that was zero. Note
2383 * that this differs from normal direct-io semantics, which
2384 * will return -EFOO even if some bytes were written.
2385 */
2386 if (written_buffered < 0) {
2387 err = written_buffered;
2388 goto out;
2389 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002391 /*
2392 * We need to ensure that the page cache pages are written to
2393 * disk and invalidated to preserve the expected O_DIRECT
2394 * semantics.
2395 */
2396 endbyte = pos + written_buffered - written - 1;
Christoph Hellwigc05c4ed2009-09-23 15:07:30 +02002397 err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002398 if (err == 0) {
2399 written = written_buffered;
2400 invalidate_mapping_pages(mapping,
2401 pos >> PAGE_CACHE_SHIFT,
2402 endbyte >> PAGE_CACHE_SHIFT);
2403 } else {
2404 /*
2405 * We don't know how much we wrote, so just return
2406 * the number of bytes which were direct-written
2407 */
2408 }
2409 } else {
2410 written = generic_file_buffered_write(iocb, iov, nr_segs,
2411 pos, ppos, count, written);
2412 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002413out:
2414 current->backing_dev_info = NULL;
2415 return written ? written : err;
2416}
Jan Karae4dd9de2009-08-17 18:10:06 +02002417EXPORT_SYMBOL(__generic_file_aio_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418
Jan Karae4dd9de2009-08-17 18:10:06 +02002419/**
2420 * generic_file_aio_write - write data to a file
2421 * @iocb: IO state structure
2422 * @iov: vector with data to write
2423 * @nr_segs: number of segments in the vector
2424 * @pos: position in file where to write
2425 *
2426 * This is a wrapper around __generic_file_aio_write() to be used by most
2427 * filesystems. It takes care of syncing the file in case of O_SYNC file
2428 * and acquires i_mutex as needed.
2429 */
Badari Pulavarty027445c2006-09-30 23:28:46 -07002430ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2431 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002432{
2433 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02002434 struct inode *inode = file->f_mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002435 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002436
2437 BUG_ON(iocb->ki_pos != pos);
2438
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002439 mutex_lock(&inode->i_mutex);
Jan Karae4dd9de2009-08-17 18:10:06 +02002440 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002441 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002442
Jan Kara148f9482009-08-17 19:52:36 +02002443 if (ret > 0 || ret == -EIOCBQUEUED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002444 ssize_t err;
2445
Jan Kara148f9482009-08-17 19:52:36 +02002446 err = generic_write_sync(file, pos, ret);
Jan Karac7b50db2009-08-18 16:18:20 +02002447 if (err < 0 && ret > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002448 ret = err;
2449 }
2450 return ret;
2451}
2452EXPORT_SYMBOL(generic_file_aio_write);
2453
David Howellscf9a2ae2006-08-29 19:05:54 +01002454/**
2455 * try_to_release_page() - release old fs-specific metadata on a page
2456 *
2457 * @page: the page which the kernel is trying to free
2458 * @gfp_mask: memory allocation flags (and I/O mode)
2459 *
2460 * The address_space is to try to release any data against the page
2461 * (presumably at page->private). If the release was successful, return `1'.
2462 * Otherwise return zero.
2463 *
David Howells266cf652009-04-03 16:42:36 +01002464 * This may also be called if PG_fscache is set on a page, indicating that the
2465 * page is known to the local caching routines.
2466 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002467 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fdd2008-07-25 01:46:22 -07002468 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002469 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002470 */
2471int try_to_release_page(struct page *page, gfp_t gfp_mask)
2472{
2473 struct address_space * const mapping = page->mapping;
2474
2475 BUG_ON(!PageLocked(page));
2476 if (PageWriteback(page))
2477 return 0;
2478
2479 if (mapping && mapping->a_ops->releasepage)
2480 return mapping->a_ops->releasepage(page, gfp_mask);
2481 return try_to_free_buffers(page);
2482}
2483
2484EXPORT_SYMBOL(try_to_release_page);