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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/mm/filemap.c
3 *
4 * Copyright (C) 1994-1999 Linus Torvalds
5 */
6
7/*
8 * This file handles the generic file mmap semantics used by
9 * most "normal" filesystems (but you don't /have/ to use this:
10 * the NFS filesystem used to do this differently, for example)
11 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/module.h>
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 *
Andi Kleen6a460792009-09-16 11:50:15 +0200105 * (code doesn't rely on that order, so you could switch it around)
106 * ->tasklist_lock (memory_failure, collect_procs_ao)
107 * ->i_mmap_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 */
109
110/*
111 * Remove a page from the page cache and free it. Caller has to make
112 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700113 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 */
115void __remove_from_page_cache(struct page *page)
116{
117 struct address_space *mapping = page->mapping;
118
119 radix_tree_delete(&mapping->page_tree, page->index);
120 page->mapping = NULL;
121 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700122 __dec_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700123 if (PageSwapBacked(page))
124 __dec_zone_page_state(page, NR_SHMEM);
Nick Piggin45426812007-07-15 23:38:12 -0700125 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800126
127 /*
128 * Some filesystems seem to re-dirty the page even after
129 * the VM has canceled the dirty bit (eg ext3 journaling).
130 *
131 * Fix it up by doing a final dirty accounting check after
132 * having removed the page entirely.
133 */
134 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
135 dec_zone_page_state(page, NR_FILE_DIRTY);
136 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
137 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138}
139
140void remove_from_page_cache(struct page *page)
141{
142 struct address_space *mapping = page->mapping;
Linus Torvalds6072d132010-12-01 13:35:19 -0500143 void (*freepage)(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Matt Mackallcd7619d2005-05-01 08:59:01 -0700145 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146
Linus Torvalds6072d132010-12-01 13:35:19 -0500147 freepage = mapping->a_ops->freepage;
Nick Piggin19fd6232008-07-25 19:45:32 -0700148 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700150 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700151 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500152
153 if (freepage)
154 freepage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700155}
Miklos Szeredia52116a2010-05-25 15:06:06 +0200156EXPORT_SYMBOL(remove_from_page_cache);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
158static int sync_page(void *word)
159{
160 struct address_space *mapping;
161 struct page *page;
162
Andi Kleen07808b72005-11-05 17:25:53 +0100163 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
165 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700166 * page_mapping() is being called without PG_locked held.
167 * Some knowledge of the state and use of the page is used to
168 * reduce the requirements down to a memory barrier.
169 * The danger here is of a stale page_mapping() return value
170 * indicating a struct address_space different from the one it's
171 * associated with when it is associated with one.
172 * After smp_mb(), it's either the correct page_mapping() for
173 * the page, or an old page_mapping() and the page's own
174 * page_mapping() has gone NULL.
175 * The ->sync_page() address_space operation must tolerate
176 * page_mapping() going NULL. By an amazing coincidence,
177 * this comes about because none of the users of the page
178 * in the ->sync_page() methods make essential use of the
179 * page_mapping(), merely passing the page down to the backing
180 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700181 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700182 * of interest. When page_mapping() does go NULL, the entire
183 * call stack gracefully ignores the page and returns.
184 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 */
186 smp_mb();
187 mapping = page_mapping(page);
188 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
189 mapping->a_ops->sync_page(page);
190 io_schedule();
191 return 0;
192}
193
Matthew Wilcox2687a352007-12-06 11:18:49 -0500194static int sync_page_killable(void *word)
195{
196 sync_page(word);
197 return fatal_signal_pending(current) ? -EINTR : 0;
198}
199
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700201 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700202 * @mapping: address space structure to write
203 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800204 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700205 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700207 * Start writeback against all of a mapping's dirty pages that lie
208 * within the byte offsets <start, end> inclusive.
209 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700211 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 * these two operations is that if a dirty page/buffer is encountered, it must
213 * be waited upon, and not just skipped over.
214 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800215int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
216 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217{
218 int ret;
219 struct writeback_control wbc = {
220 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800221 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700222 .range_start = start,
223 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 };
225
226 if (!mapping_cap_writeback_dirty(mapping))
227 return 0;
228
229 ret = do_writepages(mapping, &wbc);
230 return ret;
231}
232
233static inline int __filemap_fdatawrite(struct address_space *mapping,
234 int sync_mode)
235{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700236 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237}
238
239int filemap_fdatawrite(struct address_space *mapping)
240{
241 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
242}
243EXPORT_SYMBOL(filemap_fdatawrite);
244
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400245int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800246 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247{
248 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
249}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400250EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251
Randy Dunlap485bb992006-06-23 02:03:49 -0700252/**
253 * filemap_flush - mostly a non-blocking flush
254 * @mapping: target address_space
255 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 * This is a mostly non-blocking flush. Not suitable for data-integrity
257 * purposes - I/O may not be started against all dirty pages.
258 */
259int filemap_flush(struct address_space *mapping)
260{
261 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
262}
263EXPORT_SYMBOL(filemap_flush);
264
Randy Dunlap485bb992006-06-23 02:03:49 -0700265/**
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200266 * filemap_fdatawait_range - wait for writeback to complete
267 * @mapping: address space structure to wait for
268 * @start_byte: offset in bytes where the range starts
269 * @end_byte: offset in bytes where the range ends (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -0700270 *
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200271 * Walk the list of under-writeback pages of the given address space
272 * in the given range and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 */
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200274int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
275 loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276{
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200277 pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
278 pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 struct pagevec pvec;
280 int nr_pages;
281 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200283 if (end_byte < start_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 return 0;
285
286 pagevec_init(&pvec, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 while ((index <= end) &&
288 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
289 PAGECACHE_TAG_WRITEBACK,
290 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
291 unsigned i;
292
293 for (i = 0; i < nr_pages; i++) {
294 struct page *page = pvec.pages[i];
295
296 /* until radix tree lookup accepts end_index */
297 if (page->index > end)
298 continue;
299
300 wait_on_page_writeback(page);
Rik van Riel212260a2011-01-13 15:46:06 -0800301 if (TestClearPageError(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 ret = -EIO;
303 }
304 pagevec_release(&pvec);
305 cond_resched();
306 }
307
308 /* Check for outstanding write errors */
309 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
310 ret = -ENOSPC;
311 if (test_and_clear_bit(AS_EIO, &mapping->flags))
312 ret = -EIO;
313
314 return ret;
315}
Jan Karad3bccb62009-08-17 19:30:27 +0200316EXPORT_SYMBOL(filemap_fdatawait_range);
317
318/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700319 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700321 *
322 * Walk the list of under-writeback pages of the given address space
323 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 */
325int filemap_fdatawait(struct address_space *mapping)
326{
327 loff_t i_size = i_size_read(mapping->host);
328
329 if (i_size == 0)
330 return 0;
331
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200332 return filemap_fdatawait_range(mapping, 0, i_size - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333}
334EXPORT_SYMBOL(filemap_fdatawait);
335
336int filemap_write_and_wait(struct address_space *mapping)
337{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800338 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339
340 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800341 err = filemap_fdatawrite(mapping);
342 /*
343 * Even if the above returned error, the pages may be
344 * written partially (e.g. -ENOSPC), so we wait for it.
345 * But the -EIO is special case, it may indicate the worst
346 * thing (e.g. bug) happened, so we avoid waiting for it.
347 */
348 if (err != -EIO) {
349 int err2 = filemap_fdatawait(mapping);
350 if (!err)
351 err = err2;
352 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800354 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800356EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357
Randy Dunlap485bb992006-06-23 02:03:49 -0700358/**
359 * filemap_write_and_wait_range - write out & wait on a file range
360 * @mapping: the address_space for the pages
361 * @lstart: offset in bytes where the range starts
362 * @lend: offset in bytes where the range ends (inclusive)
363 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800364 * Write out and wait upon file offsets lstart->lend, inclusive.
365 *
366 * Note that `lend' is inclusive (describes the last byte to be written) so
367 * that this function can be used to write to the very end-of-file (end = -1).
368 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369int filemap_write_and_wait_range(struct address_space *mapping,
370 loff_t lstart, loff_t lend)
371{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800372 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373
374 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800375 err = __filemap_fdatawrite_range(mapping, lstart, lend,
376 WB_SYNC_ALL);
377 /* See comment of filemap_write_and_wait() */
378 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200379 int err2 = filemap_fdatawait_range(mapping,
380 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800381 if (!err)
382 err = err2;
383 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800385 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386}
Chris Masonf6995582009-04-15 13:22:37 -0400387EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388
Randy Dunlap485bb992006-06-23 02:03:49 -0700389/**
Nick Piggine2867812008-07-25 19:45:30 -0700390 * add_to_page_cache_locked - add a locked page to the pagecache
Randy Dunlap485bb992006-06-23 02:03:49 -0700391 * @page: page to add
392 * @mapping: the page's address_space
393 * @offset: page index
394 * @gfp_mask: page allocation mode
395 *
Nick Piggine2867812008-07-25 19:45:30 -0700396 * This function is used to add a page to the pagecache. It must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 * This function does not add the page to the LRU. The caller must do that.
398 */
Nick Piggine2867812008-07-25 19:45:30 -0700399int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400400 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401{
Nick Piggine2867812008-07-25 19:45:30 -0700402 int error;
403
404 VM_BUG_ON(!PageLocked(page));
405
406 error = mem_cgroup_cache_charge(page, current->mm,
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -0800407 gfp_mask & GFP_RECLAIM_MASK);
Balbir Singh35c754d2008-02-07 00:14:05 -0800408 if (error)
409 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410
Balbir Singh35c754d2008-02-07 00:14:05 -0800411 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 if (error == 0) {
Nick Piggine2867812008-07-25 19:45:30 -0700413 page_cache_get(page);
414 page->mapping = mapping;
415 page->index = offset;
416
Nick Piggin19fd6232008-07-25 19:45:32 -0700417 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 error = radix_tree_insert(&mapping->page_tree, offset, page);
Nick Piggine2867812008-07-25 19:45:30 -0700419 if (likely(!error)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700421 __inc_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700422 if (PageSwapBacked(page))
423 __inc_zone_page_state(page, NR_SHMEM);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700424 spin_unlock_irq(&mapping->tree_lock);
Nick Piggine2867812008-07-25 19:45:30 -0700425 } else {
426 page->mapping = NULL;
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700427 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700428 mem_cgroup_uncharge_cache_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700429 page_cache_release(page);
430 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800432 } else
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700433 mem_cgroup_uncharge_cache_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800434out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 return error;
436}
Nick Piggine2867812008-07-25 19:45:30 -0700437EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438
439int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400440 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700442 int ret;
443
444 /*
445 * Splice_read and readahead add shmem/tmpfs pages into the page cache
446 * before shmem_readpage has a chance to mark them as SwapBacked: they
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700447 * need to go on the anon lru below, and mem_cgroup_cache_charge
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700448 * (called in add_to_page_cache) needs to know where they're going too.
449 */
450 if (mapping_cap_swap_backed(mapping))
451 SetPageSwapBacked(page);
452
453 ret = add_to_page_cache(page, mapping, offset, gfp_mask);
454 if (ret == 0) {
455 if (page_is_file_cache(page))
456 lru_cache_add_file(page);
457 else
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700458 lru_cache_add_anon(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700459 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 return ret;
461}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300462EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463
Paul Jackson44110fe2006-03-24 03:16:04 -0800464#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700465struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800466{
Miao Xiec0ff7452010-05-24 14:32:08 -0700467 int n;
468 struct page *page;
469
Paul Jackson44110fe2006-03-24 03:16:04 -0800470 if (cpuset_do_page_mem_spread()) {
Miao Xiec0ff7452010-05-24 14:32:08 -0700471 get_mems_allowed();
472 n = cpuset_mem_spread_node();
473 page = alloc_pages_exact_node(n, gfp, 0);
474 put_mems_allowed();
475 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800476 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700477 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800478}
Nick Piggin2ae88142006-10-28 10:38:23 -0700479EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800480#endif
481
Nick Piggindb376482006-09-25 23:31:24 -0700482static int __sleep_on_page_lock(void *word)
483{
484 io_schedule();
485 return 0;
486}
487
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488/*
489 * In order to wait for pages to become available there must be
490 * waitqueues associated with pages. By using a hash table of
491 * waitqueues where the bucket discipline is to maintain all
492 * waiters on the same queue and wake all when any of the pages
493 * become available, and for the woken contexts to check to be
494 * sure the appropriate page became available, this saves space
495 * at a cost of "thundering herd" phenomena during rare hash
496 * collisions.
497 */
498static wait_queue_head_t *page_waitqueue(struct page *page)
499{
500 const struct zone *zone = page_zone(page);
501
502 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
503}
504
505static inline void wake_up_page(struct page *page, int bit)
506{
507 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
508}
509
Harvey Harrison920c7a52008-02-04 22:29:26 -0800510void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511{
512 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
513
514 if (test_bit(bit_nr, &page->flags))
515 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
516 TASK_UNINTERRUPTIBLE);
517}
518EXPORT_SYMBOL(wait_on_page_bit);
519
520/**
David Howells385e1ca2009-04-03 16:42:39 +0100521 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -0700522 * @page: Page defining the wait queue of interest
523 * @waiter: Waiter to add to the queue
David Howells385e1ca2009-04-03 16:42:39 +0100524 *
525 * Add an arbitrary @waiter to the wait queue for the nominated @page.
526 */
527void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
528{
529 wait_queue_head_t *q = page_waitqueue(page);
530 unsigned long flags;
531
532 spin_lock_irqsave(&q->lock, flags);
533 __add_wait_queue(q, waiter);
534 spin_unlock_irqrestore(&q->lock, flags);
535}
536EXPORT_SYMBOL_GPL(add_page_wait_queue);
537
538/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700539 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 * @page: the page
541 *
542 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
543 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
544 * mechananism between PageLocked pages and PageWriteback pages is shared.
545 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
546 *
Nick Piggin8413ac92008-10-18 20:26:59 -0700547 * The mb is necessary to enforce ordering between the clear_bit and the read
548 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800550void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551{
Nick Piggin8413ac92008-10-18 20:26:59 -0700552 VM_BUG_ON(!PageLocked(page));
553 clear_bit_unlock(PG_locked, &page->flags);
554 smp_mb__after_clear_bit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 wake_up_page(page, PG_locked);
556}
557EXPORT_SYMBOL(unlock_page);
558
Randy Dunlap485bb992006-06-23 02:03:49 -0700559/**
560 * end_page_writeback - end writeback against a page
561 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 */
563void end_page_writeback(struct page *page)
564{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700565 if (TestClearPageReclaim(page))
566 rotate_reclaimable_page(page);
567
568 if (!test_clear_page_writeback(page))
569 BUG();
570
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 smp_mb__after_clear_bit();
572 wake_up_page(page, PG_writeback);
573}
574EXPORT_SYMBOL(end_page_writeback);
575
Randy Dunlap485bb992006-06-23 02:03:49 -0700576/**
577 * __lock_page - get a lock on the page, assuming we need to sleep to get it
578 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700580 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
582 * chances are that on the second loop, the block layer's plug list is empty,
583 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
584 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800585void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586{
587 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
588
589 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
590 TASK_UNINTERRUPTIBLE);
591}
592EXPORT_SYMBOL(__lock_page);
593
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800594int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500595{
596 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
597
598 return __wait_on_bit_lock(page_waitqueue(page), &wait,
599 sync_page_killable, TASK_KILLABLE);
600}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300601EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500602
Randy Dunlap76824862008-03-19 17:00:40 -0700603/**
604 * __lock_page_nosync - get a lock on the page, without calling sync_page()
605 * @page: the page to lock
606 *
Nick Piggindb376482006-09-25 23:31:24 -0700607 * Variant of lock_page that does not require the caller to hold a reference
608 * on the page's mapping.
609 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800610void __lock_page_nosync(struct page *page)
Nick Piggindb376482006-09-25 23:31:24 -0700611{
612 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
613 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
614 TASK_UNINTERRUPTIBLE);
615}
616
Michel Lespinassed065bd82010-10-26 14:21:57 -0700617int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
618 unsigned int flags)
619{
620 if (!(flags & FAULT_FLAG_ALLOW_RETRY)) {
621 __lock_page(page);
622 return 1;
623 } else {
624 up_read(&mm->mmap_sem);
625 wait_on_page_locked(page);
626 return 0;
627 }
628}
629
Randy Dunlap485bb992006-06-23 02:03:49 -0700630/**
631 * find_get_page - find and get a page reference
632 * @mapping: the address_space to search
633 * @offset: the page index
634 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700635 * Is there a pagecache struct page at the given (mapping, offset) tuple?
636 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637 */
Nick Piggina60637c2008-07-25 19:45:31 -0700638struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639{
Nick Piggina60637c2008-07-25 19:45:31 -0700640 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 struct page *page;
642
Nick Piggina60637c2008-07-25 19:45:31 -0700643 rcu_read_lock();
644repeat:
645 page = NULL;
646 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
647 if (pagep) {
648 page = radix_tree_deref_slot(pagep);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800649 if (unlikely(!page))
650 goto out;
651 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700652 goto repeat;
653
654 if (!page_cache_get_speculative(page))
655 goto repeat;
656
657 /*
658 * Has the page moved?
659 * This is part of the lockless pagecache protocol. See
660 * include/linux/pagemap.h for details.
661 */
662 if (unlikely(page != *pagep)) {
663 page_cache_release(page);
664 goto repeat;
665 }
666 }
Nick Piggin27d20fd2010-11-11 14:05:19 -0800667out:
Nick Piggina60637c2008-07-25 19:45:31 -0700668 rcu_read_unlock();
669
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 return page;
671}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672EXPORT_SYMBOL(find_get_page);
673
Randy Dunlap485bb992006-06-23 02:03:49 -0700674/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700676 * @mapping: the address_space to search
677 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 *
679 * Locates the desired pagecache page, locks it, increments its reference
680 * count and returns its address.
681 *
682 * Returns zero if the page was not present. find_lock_page() may sleep.
683 */
Nick Piggina60637c2008-07-25 19:45:31 -0700684struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685{
686 struct page *page;
687
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688repeat:
Nick Piggina60637c2008-07-25 19:45:31 -0700689 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 if (page) {
Nick Piggina60637c2008-07-25 19:45:31 -0700691 lock_page(page);
692 /* Has the page been truncated? */
693 if (unlikely(page->mapping != mapping)) {
694 unlock_page(page);
695 page_cache_release(page);
696 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 }
Nick Piggina60637c2008-07-25 19:45:31 -0700698 VM_BUG_ON(page->index != offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 return page;
701}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702EXPORT_SYMBOL(find_lock_page);
703
704/**
705 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700706 * @mapping: the page's address_space
707 * @index: the page's index into the mapping
708 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 *
710 * Locates a page in the pagecache. If the page is not present, a new page
711 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
712 * LRU list. The returned page is locked and has its reference count
713 * incremented.
714 *
715 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
716 * allocation!
717 *
718 * find_or_create_page() returns the desired page's address, or zero on
719 * memory exhaustion.
720 */
721struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700722 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723{
Nick Piggineb2be182007-10-16 01:24:57 -0700724 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 int err;
726repeat:
727 page = find_lock_page(mapping, index);
728 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700729 page = __page_cache_alloc(gfp_mask);
730 if (!page)
731 return NULL;
Nick Piggin67d58ac2009-01-06 14:40:28 -0800732 /*
733 * We want a regular kernel memory (not highmem or DMA etc)
734 * allocation for the radix tree nodes, but we need to honour
735 * the context-specific requirements the caller has asked for.
736 * GFP_RECLAIM_MASK collects those requirements.
737 */
738 err = add_to_page_cache_lru(page, mapping, index,
739 (gfp_mask & GFP_RECLAIM_MASK));
Nick Piggineb2be182007-10-16 01:24:57 -0700740 if (unlikely(err)) {
741 page_cache_release(page);
742 page = NULL;
743 if (err == -EEXIST)
744 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 return page;
748}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749EXPORT_SYMBOL(find_or_create_page);
750
751/**
752 * find_get_pages - gang pagecache lookup
753 * @mapping: The address_space to search
754 * @start: The starting page index
755 * @nr_pages: The maximum number of pages
756 * @pages: Where the resulting pages are placed
757 *
758 * find_get_pages() will search for and return a group of up to
759 * @nr_pages pages in the mapping. The pages are placed at @pages.
760 * find_get_pages() takes a reference against the returned pages.
761 *
762 * The search returns a group of mapping-contiguous pages with ascending
763 * indexes. There may be holes in the indices due to not-present pages.
764 *
765 * find_get_pages() returns the number of pages which were found.
766 */
767unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
768 unsigned int nr_pages, struct page **pages)
769{
770 unsigned int i;
771 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700772 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773
Nick Piggina60637c2008-07-25 19:45:31 -0700774 rcu_read_lock();
775restart:
776 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
777 (void ***)pages, start, nr_pages);
778 ret = 0;
779 for (i = 0; i < nr_found; i++) {
780 struct page *page;
781repeat:
782 page = radix_tree_deref_slot((void **)pages[i]);
783 if (unlikely(!page))
784 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800785 if (radix_tree_deref_retry(page)) {
786 if (ret)
787 start = pages[ret-1]->index;
Nick Piggina60637c2008-07-25 19:45:31 -0700788 goto restart;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800789 }
Nick Piggina60637c2008-07-25 19:45:31 -0700790
791 if (!page_cache_get_speculative(page))
792 goto repeat;
793
794 /* Has the page moved? */
795 if (unlikely(page != *((void **)pages[i]))) {
796 page_cache_release(page);
797 goto repeat;
798 }
799
800 pages[ret] = page;
801 ret++;
802 }
803 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 return ret;
805}
806
Jens Axboeebf43502006-04-27 08:46:01 +0200807/**
808 * find_get_pages_contig - gang contiguous pagecache lookup
809 * @mapping: The address_space to search
810 * @index: The starting page index
811 * @nr_pages: The maximum number of pages
812 * @pages: Where the resulting pages are placed
813 *
814 * find_get_pages_contig() works exactly like find_get_pages(), except
815 * that the returned number of pages are guaranteed to be contiguous.
816 *
817 * find_get_pages_contig() returns the number of pages which were found.
818 */
819unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
820 unsigned int nr_pages, struct page **pages)
821{
822 unsigned int i;
823 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700824 unsigned int nr_found;
Jens Axboeebf43502006-04-27 08:46:01 +0200825
Nick Piggina60637c2008-07-25 19:45:31 -0700826 rcu_read_lock();
827restart:
828 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
829 (void ***)pages, index, nr_pages);
830 ret = 0;
831 for (i = 0; i < nr_found; i++) {
832 struct page *page;
833repeat:
834 page = radix_tree_deref_slot((void **)pages[i]);
835 if (unlikely(!page))
836 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800837 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700838 goto restart;
839
Nick Piggina60637c2008-07-25 19:45:31 -0700840 if (!page_cache_get_speculative(page))
841 goto repeat;
842
843 /* Has the page moved? */
844 if (unlikely(page != *((void **)pages[i]))) {
845 page_cache_release(page);
846 goto repeat;
847 }
848
Nick Piggin9cbb4cb2011-01-13 15:45:51 -0800849 /*
850 * must check mapping and index after taking the ref.
851 * otherwise we can get both false positives and false
852 * negatives, which is just confusing to the caller.
853 */
854 if (page->mapping == NULL || page->index != index) {
855 page_cache_release(page);
856 break;
857 }
858
Nick Piggina60637c2008-07-25 19:45:31 -0700859 pages[ret] = page;
860 ret++;
Jens Axboeebf43502006-04-27 08:46:01 +0200861 index++;
862 }
Nick Piggina60637c2008-07-25 19:45:31 -0700863 rcu_read_unlock();
864 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +0200865}
David Howellsef71c152007-05-09 02:33:44 -0700866EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200867
Randy Dunlap485bb992006-06-23 02:03:49 -0700868/**
869 * find_get_pages_tag - find and return pages that match @tag
870 * @mapping: the address_space to search
871 * @index: the starting page index
872 * @tag: the tag index
873 * @nr_pages: the maximum number of pages
874 * @pages: where the resulting pages are placed
875 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700877 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 */
879unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
880 int tag, unsigned int nr_pages, struct page **pages)
881{
882 unsigned int i;
883 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700884 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885
Nick Piggina60637c2008-07-25 19:45:31 -0700886 rcu_read_lock();
887restart:
888 nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
889 (void ***)pages, *index, nr_pages, tag);
890 ret = 0;
891 for (i = 0; i < nr_found; i++) {
892 struct page *page;
893repeat:
894 page = radix_tree_deref_slot((void **)pages[i]);
895 if (unlikely(!page))
896 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800897 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700898 goto restart;
899
900 if (!page_cache_get_speculative(page))
901 goto repeat;
902
903 /* Has the page moved? */
904 if (unlikely(page != *((void **)pages[i]))) {
905 page_cache_release(page);
906 goto repeat;
907 }
908
909 pages[ret] = page;
910 ret++;
911 }
912 rcu_read_unlock();
913
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 if (ret)
915 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -0700916
Linus Torvalds1da177e2005-04-16 15:20:36 -0700917 return ret;
918}
David Howellsef71c152007-05-09 02:33:44 -0700919EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920
Randy Dunlap485bb992006-06-23 02:03:49 -0700921/**
922 * grab_cache_page_nowait - returns locked page at given index in given cache
923 * @mapping: target address_space
924 * @index: the page index
925 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800926 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 * This is intended for speculative data generators, where the data can
928 * be regenerated if the page couldn't be grabbed. This routine should
929 * be safe to call while holding the lock for another page.
930 *
931 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
932 * and deadlock against the caller's locked page.
933 */
934struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700935grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936{
937 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938
939 if (page) {
Nick Piggin529ae9a2008-08-02 12:01:03 +0200940 if (trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941 return page;
942 page_cache_release(page);
943 return NULL;
944 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700945 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
Nick Piggin67d58ac2009-01-06 14:40:28 -0800946 if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947 page_cache_release(page);
948 page = NULL;
949 }
950 return page;
951}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952EXPORT_SYMBOL(grab_cache_page_nowait);
953
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700954/*
955 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
956 * a _large_ part of the i/o request. Imagine the worst scenario:
957 *
958 * ---R__________________________________________B__________
959 * ^ reading here ^ bad block(assume 4k)
960 *
961 * read(R) => miss => readahead(R...B) => media error => frustrating retries
962 * => failing the whole request => read(R) => read(R+1) =>
963 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
964 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
965 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
966 *
967 * It is going insane. Fix it by quickly scaling down the readahead size.
968 */
969static void shrink_readahead_size_eio(struct file *filp,
970 struct file_ra_state *ra)
971{
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700972 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700973}
974
Randy Dunlap485bb992006-06-23 02:03:49 -0700975/**
Christoph Hellwig36e78912008-02-08 04:21:24 -0800976 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -0700977 * @filp: the file to read
978 * @ppos: current file position
979 * @desc: read_descriptor
980 * @actor: read method
981 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700982 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700983 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 *
985 * This is really ugly. But the goto's actually try to clarify some
986 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 */
Christoph Hellwig36e78912008-02-08 04:21:24 -0800988static void do_generic_file_read(struct file *filp, loff_t *ppos,
989 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990{
Christoph Hellwig36e78912008-02-08 04:21:24 -0800991 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -0800993 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700994 pgoff_t index;
995 pgoff_t last_index;
996 pgoff_t prev_index;
997 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -0700998 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001001 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -07001002 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
1003 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
1005 offset = *ppos & ~PAGE_CACHE_MASK;
1006
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007 for (;;) {
1008 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001009 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -07001010 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 unsigned long nr, ret;
1012
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014find_page:
1015 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001016 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001017 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001018 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001019 index, last_index - index);
1020 page = find_get_page(mapping, index);
1021 if (unlikely(page == NULL))
1022 goto no_cached_page;
1023 }
1024 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001025 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001026 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001027 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001029 if (!PageUptodate(page)) {
1030 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1031 !mapping->a_ops->is_partially_uptodate)
1032 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001033 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001034 goto page_not_up_to_date;
Dave Hansen8d056cb2010-11-11 14:05:15 -08001035 /* Did it get truncated before we got the lock? */
1036 if (!page->mapping)
1037 goto page_not_up_to_date_locked;
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001038 if (!mapping->a_ops->is_partially_uptodate(page,
1039 desc, offset))
1040 goto page_not_up_to_date_locked;
1041 unlock_page(page);
1042 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001044 /*
1045 * i_size must be checked after we know the page is Uptodate.
1046 *
1047 * Checking i_size after the check allows us to calculate
1048 * the correct value for "nr", which means the zero-filled
1049 * part of the page is not copied back to userspace (unless
1050 * another truncate extends the file - this is desired though).
1051 */
1052
1053 isize = i_size_read(inode);
1054 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1055 if (unlikely(!isize || index > end_index)) {
1056 page_cache_release(page);
1057 goto out;
1058 }
1059
1060 /* nr is the maximum number of bytes to copy from this page */
1061 nr = PAGE_CACHE_SIZE;
1062 if (index == end_index) {
1063 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1064 if (nr <= offset) {
1065 page_cache_release(page);
1066 goto out;
1067 }
1068 }
1069 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070
1071 /* If users can be writing to this page using arbitrary
1072 * virtual addresses, take care about potential aliasing
1073 * before reading the page on the kernel side.
1074 */
1075 if (mapping_writably_mapped(mapping))
1076 flush_dcache_page(page);
1077
1078 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001079 * When a sequential read accesses a page several times,
1080 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081 */
Jan Karaec0f1632007-05-06 14:49:25 -07001082 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 mark_page_accessed(page);
1084 prev_index = index;
1085
1086 /*
1087 * Ok, we have the page, and it's up-to-date, so
1088 * now we can copy it to user space...
1089 *
1090 * The actor routine returns how many bytes were actually used..
1091 * NOTE! This may not be the same as how much of a user buffer
1092 * we filled up (we may be padding etc), so we can only update
1093 * "pos" here (the actor routine has to update the user buffer
1094 * pointers and the remaining count).
1095 */
1096 ret = actor(desc, page, offset, nr);
1097 offset += ret;
1098 index += offset >> PAGE_CACHE_SHIFT;
1099 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001100 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101
1102 page_cache_release(page);
1103 if (ret == nr && desc->count)
1104 continue;
1105 goto out;
1106
1107page_not_up_to_date:
1108 /* Get exclusive access to the page ... */
Oleg Nesterov85462322008-06-08 21:20:43 +04001109 error = lock_page_killable(page);
1110 if (unlikely(error))
1111 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001113page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001114 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 if (!page->mapping) {
1116 unlock_page(page);
1117 page_cache_release(page);
1118 continue;
1119 }
1120
1121 /* Did somebody else fill it already? */
1122 if (PageUptodate(page)) {
1123 unlock_page(page);
1124 goto page_ok;
1125 }
1126
1127readpage:
Jeff Moyer91803b42010-05-26 11:49:40 -04001128 /*
1129 * A previous I/O error may have been due to temporary
1130 * failures, eg. multipath errors.
1131 * PG_error will be set again if readpage fails.
1132 */
1133 ClearPageError(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 /* Start the actual read. The read will unlock the page. */
1135 error = mapping->a_ops->readpage(filp, page);
1136
Zach Brown994fc28c2005-12-15 14:28:17 -08001137 if (unlikely(error)) {
1138 if (error == AOP_TRUNCATED_PAGE) {
1139 page_cache_release(page);
1140 goto find_page;
1141 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001143 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144
1145 if (!PageUptodate(page)) {
Oleg Nesterov85462322008-06-08 21:20:43 +04001146 error = lock_page_killable(page);
1147 if (unlikely(error))
1148 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 if (!PageUptodate(page)) {
1150 if (page->mapping == NULL) {
1151 /*
Christoph Hellwig2ecdc822010-01-26 17:27:20 +01001152 * invalidate_mapping_pages got it
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 */
1154 unlock_page(page);
1155 page_cache_release(page);
1156 goto find_page;
1157 }
1158 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001159 shrink_readahead_size_eio(filp, ra);
Oleg Nesterov85462322008-06-08 21:20:43 +04001160 error = -EIO;
1161 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 }
1163 unlock_page(page);
1164 }
1165
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 goto page_ok;
1167
1168readpage_error:
1169 /* UHHUH! A synchronous read error occurred. Report it */
1170 desc->error = error;
1171 page_cache_release(page);
1172 goto out;
1173
1174no_cached_page:
1175 /*
1176 * Ok, it wasn't cached, so we need to create a new
1177 * page..
1178 */
Nick Piggineb2be182007-10-16 01:24:57 -07001179 page = page_cache_alloc_cold(mapping);
1180 if (!page) {
1181 desc->error = -ENOMEM;
1182 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 }
Nick Piggineb2be182007-10-16 01:24:57 -07001184 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185 index, GFP_KERNEL);
1186 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001187 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188 if (error == -EEXIST)
1189 goto find_page;
1190 desc->error = error;
1191 goto out;
1192 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 goto readpage;
1194 }
1195
1196out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001197 ra->prev_pos = prev_index;
1198 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1199 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001201 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Krishna Kumar0c6aa262008-10-15 22:01:13 -07001202 file_accessed(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204
1205int file_read_actor(read_descriptor_t *desc, struct page *page,
1206 unsigned long offset, unsigned long size)
1207{
1208 char *kaddr;
1209 unsigned long left, count = desc->count;
1210
1211 if (size > count)
1212 size = count;
1213
1214 /*
1215 * Faults on the destination of a read are common, so do it before
1216 * taking the kmap.
1217 */
1218 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1219 kaddr = kmap_atomic(page, KM_USER0);
1220 left = __copy_to_user_inatomic(desc->arg.buf,
1221 kaddr + offset, size);
1222 kunmap_atomic(kaddr, KM_USER0);
1223 if (left == 0)
1224 goto success;
1225 }
1226
1227 /* Do it the slow way */
1228 kaddr = kmap(page);
1229 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1230 kunmap(page);
1231
1232 if (left) {
1233 size -= left;
1234 desc->error = -EFAULT;
1235 }
1236success:
1237 desc->count = count - size;
1238 desc->written += size;
1239 desc->arg.buf += size;
1240 return size;
1241}
1242
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001243/*
1244 * Performs necessary checks before doing a write
1245 * @iov: io vector request
1246 * @nr_segs: number of segments in the iovec
1247 * @count: number of bytes to write
1248 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1249 *
1250 * Adjust number of segments and amount of bytes to write (nr_segs should be
1251 * properly initialized first). Returns appropriate error code that caller
1252 * should return or zero in case that write should be allowed.
1253 */
1254int generic_segment_checks(const struct iovec *iov,
1255 unsigned long *nr_segs, size_t *count, int access_flags)
1256{
1257 unsigned long seg;
1258 size_t cnt = 0;
1259 for (seg = 0; seg < *nr_segs; seg++) {
1260 const struct iovec *iv = &iov[seg];
1261
1262 /*
1263 * If any segment has a negative length, or the cumulative
1264 * length ever wraps negative then return -EINVAL.
1265 */
1266 cnt += iv->iov_len;
1267 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1268 return -EINVAL;
1269 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1270 continue;
1271 if (seg == 0)
1272 return -EFAULT;
1273 *nr_segs = seg;
1274 cnt -= iv->iov_len; /* This segment is no good */
1275 break;
1276 }
1277 *count = cnt;
1278 return 0;
1279}
1280EXPORT_SYMBOL(generic_segment_checks);
1281
Randy Dunlap485bb992006-06-23 02:03:49 -07001282/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001283 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001284 * @iocb: kernel I/O control block
1285 * @iov: io vector request
1286 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001287 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001288 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 * This is the "read()" routine for all filesystems
1290 * that can use the page cache directly.
1291 */
1292ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001293generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1294 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295{
1296 struct file *filp = iocb->ki_filp;
1297 ssize_t retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001298 unsigned long seg = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001300 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301
1302 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001303 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1304 if (retval)
1305 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306
1307 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1308 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001309 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310 struct address_space *mapping;
1311 struct inode *inode;
1312
1313 mapping = filp->f_mapping;
1314 inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 if (!count)
1316 goto out; /* skip atime */
1317 size = i_size_read(inode);
1318 if (pos < size) {
Nick Piggin48b47c52009-01-06 14:40:22 -08001319 retval = filemap_write_and_wait_range(mapping, pos,
1320 pos + iov_length(iov, nr_segs) - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07001321 if (!retval) {
1322 retval = mapping->a_ops->direct_IO(READ, iocb,
1323 iov, pos, nr_segs);
1324 }
Josef Bacik66f998f2010-05-23 11:00:54 -04001325 if (retval > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326 *ppos = pos + retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001327 count -= retval;
1328 }
1329
1330 /*
1331 * Btrfs can have a short DIO read if we encounter
1332 * compressed extents, so if there was an error, or if
1333 * we've already read everything we wanted to, or if
1334 * there was a short read because we hit EOF, go ahead
1335 * and return. Otherwise fallthrough to buffered io for
1336 * the rest of the read.
1337 */
1338 if (retval < 0 || !count || *ppos >= size) {
Hugh Dickins11fa9772008-07-23 21:27:34 -07001339 file_accessed(filp);
1340 goto out;
1341 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001342 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343 }
1344
Josef Bacik66f998f2010-05-23 11:00:54 -04001345 count = retval;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001346 for (seg = 0; seg < nr_segs; seg++) {
1347 read_descriptor_t desc;
Josef Bacik66f998f2010-05-23 11:00:54 -04001348 loff_t offset = 0;
1349
1350 /*
1351 * If we did a short DIO read we need to skip the section of the
1352 * iov that we've already read data into.
1353 */
1354 if (count) {
1355 if (count > iov[seg].iov_len) {
1356 count -= iov[seg].iov_len;
1357 continue;
1358 }
1359 offset = count;
1360 count = 0;
1361 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362
Hugh Dickins11fa9772008-07-23 21:27:34 -07001363 desc.written = 0;
Josef Bacik66f998f2010-05-23 11:00:54 -04001364 desc.arg.buf = iov[seg].iov_base + offset;
1365 desc.count = iov[seg].iov_len - offset;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001366 if (desc.count == 0)
1367 continue;
1368 desc.error = 0;
1369 do_generic_file_read(filp, ppos, &desc, file_read_actor);
1370 retval += desc.written;
1371 if (desc.error) {
1372 retval = retval ?: desc.error;
1373 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 }
Hugh Dickins11fa9772008-07-23 21:27:34 -07001375 if (desc.count > 0)
1376 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 }
1378out:
1379 return retval;
1380}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381EXPORT_SYMBOL(generic_file_aio_read);
1382
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383static ssize_t
1384do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001385 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001386{
1387 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1388 return -EINVAL;
1389
Wu Fengguangf7e839d2009-06-16 15:31:20 -07001390 force_page_cache_readahead(mapping, filp, index, nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 return 0;
1392}
1393
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001394SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001395{
1396 ssize_t ret;
1397 struct file *file;
1398
1399 ret = -EBADF;
1400 file = fget(fd);
1401 if (file) {
1402 if (file->f_mode & FMODE_READ) {
1403 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001404 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1405 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406 unsigned long len = end - start + 1;
1407 ret = do_readahead(mapping, file, start, len);
1408 }
1409 fput(file);
1410 }
1411 return ret;
1412}
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001413#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1414asmlinkage long SyS_readahead(long fd, loff_t offset, long count)
1415{
1416 return SYSC_readahead((int) fd, offset, (size_t) count);
1417}
1418SYSCALL_ALIAS(sys_readahead, SyS_readahead);
1419#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001420
1421#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001422/**
1423 * page_cache_read - adds requested page to the page cache if not already there
1424 * @file: file to read
1425 * @offset: page index
1426 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 * This adds the requested page to the page cache if it isn't already there,
1428 * and schedules an I/O to read in its contents from disk.
1429 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001430static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431{
1432 struct address_space *mapping = file->f_mapping;
1433 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001434 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435
Zach Brown994fc28c2005-12-15 14:28:17 -08001436 do {
1437 page = page_cache_alloc_cold(mapping);
1438 if (!page)
1439 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440
Zach Brown994fc28c2005-12-15 14:28:17 -08001441 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1442 if (ret == 0)
1443 ret = mapping->a_ops->readpage(file, page);
1444 else if (ret == -EEXIST)
1445 ret = 0; /* losing race to add is OK */
1446
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448
Zach Brown994fc28c2005-12-15 14:28:17 -08001449 } while (ret == AOP_TRUNCATED_PAGE);
1450
1451 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452}
1453
1454#define MMAP_LOTSAMISS (100)
1455
Linus Torvaldsef00e082009-06-16 15:31:25 -07001456/*
1457 * Synchronous readahead happens when we don't even find
1458 * a page in the page cache at all.
1459 */
1460static void do_sync_mmap_readahead(struct vm_area_struct *vma,
1461 struct file_ra_state *ra,
1462 struct file *file,
1463 pgoff_t offset)
1464{
1465 unsigned long ra_pages;
1466 struct address_space *mapping = file->f_mapping;
1467
1468 /* If we don't want any read-ahead, don't bother */
1469 if (VM_RandomReadHint(vma))
1470 return;
1471
Wu Fengguang70ac23c2009-06-16 15:31:28 -07001472 if (VM_SequentialReadHint(vma) ||
1473 offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) {
Wu Fengguang7ffc59b2009-06-16 15:31:38 -07001474 page_cache_sync_readahead(mapping, ra, file, offset,
1475 ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001476 return;
1477 }
1478
1479 if (ra->mmap_miss < INT_MAX)
1480 ra->mmap_miss++;
1481
1482 /*
1483 * Do we miss much more than hit in this file? If so,
1484 * stop bothering with read-ahead. It will only hurt.
1485 */
1486 if (ra->mmap_miss > MMAP_LOTSAMISS)
1487 return;
1488
Wu Fengguangd30a1102009-06-16 15:31:30 -07001489 /*
1490 * mmap read-around
1491 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001492 ra_pages = max_sane_readahead(ra->ra_pages);
1493 if (ra_pages) {
Wu Fengguangd30a1102009-06-16 15:31:30 -07001494 ra->start = max_t(long, 0, offset - ra_pages/2);
1495 ra->size = ra_pages;
1496 ra->async_size = 0;
1497 ra_submit(ra, mapping, file);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001498 }
1499}
1500
1501/*
1502 * Asynchronous readahead happens when we find the page and PG_readahead,
1503 * so we want to possibly extend the readahead further..
1504 */
1505static void do_async_mmap_readahead(struct vm_area_struct *vma,
1506 struct file_ra_state *ra,
1507 struct file *file,
1508 struct page *page,
1509 pgoff_t offset)
1510{
1511 struct address_space *mapping = file->f_mapping;
1512
1513 /* If we don't want any read-ahead, don't bother */
1514 if (VM_RandomReadHint(vma))
1515 return;
1516 if (ra->mmap_miss > 0)
1517 ra->mmap_miss--;
1518 if (PageReadahead(page))
Wu Fengguang2fad6f52009-06-16 15:31:29 -07001519 page_cache_async_readahead(mapping, ra, file,
1520 page, offset, ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001521}
1522
Randy Dunlap485bb992006-06-23 02:03:49 -07001523/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001524 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001525 * @vma: vma in which the fault was taken
1526 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001527 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001528 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 * mapped memory region to read in file data during a page fault.
1530 *
1531 * The goto's are kind of ugly, but this streamlines the normal case of having
1532 * it in the page cache, and handles the special cases reasonably without
1533 * having a lot of duplicated code.
1534 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001535int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536{
1537 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001538 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 struct address_space *mapping = file->f_mapping;
1540 struct file_ra_state *ra = &file->f_ra;
1541 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001542 pgoff_t offset = vmf->pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001544 pgoff_t size;
Nick Piggin83c54072007-07-19 01:47:05 -07001545 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001548 if (offset >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001549 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 * Do we have something in the page cache already?
1553 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001554 page = find_get_page(mapping, offset);
1555 if (likely(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07001557 * We found the page, so try async readahead before
1558 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001560 do_async_mmap_readahead(vma, ra, file, page, offset);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001561 } else {
1562 /* No page in the page cache at all */
1563 do_sync_mmap_readahead(vma, ra, file, offset);
1564 count_vm_event(PGMAJFAULT);
1565 ret = VM_FAULT_MAJOR;
1566retry_find:
Michel Lespinasseb522c942010-10-26 14:21:56 -07001567 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 if (!page)
1569 goto no_cached_page;
1570 }
1571
Michel Lespinassed88c0922010-11-02 13:05:18 -07001572 if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
1573 page_cache_release(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -07001574 return ret | VM_FAULT_RETRY;
Michel Lespinassed88c0922010-11-02 13:05:18 -07001575 }
Michel Lespinasseb522c942010-10-26 14:21:56 -07001576
1577 /* Did it get truncated? */
1578 if (unlikely(page->mapping != mapping)) {
1579 unlock_page(page);
1580 put_page(page);
1581 goto retry_find;
1582 }
1583 VM_BUG_ON(page->index != offset);
1584
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001586 * We have a locked page in the page cache, now we need to check
1587 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588 */
Nick Piggind00806b2007-07-19 01:46:57 -07001589 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 goto page_not_uptodate;
1591
Linus Torvaldsef00e082009-06-16 15:31:25 -07001592 /*
1593 * Found the page and have a reference on it.
1594 * We must recheck i_size under page lock.
1595 */
Nick Piggind00806b2007-07-19 01:46:57 -07001596 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001597 if (unlikely(offset >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001598 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001599 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001600 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001601 }
1602
Linus Torvaldsef00e082009-06-16 15:31:25 -07001603 ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001604 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001605 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607no_cached_page:
1608 /*
1609 * We're only likely to ever get here if MADV_RANDOM is in
1610 * effect.
1611 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001612 error = page_cache_read(file, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613
1614 /*
1615 * The page we want has now been added to the page cache.
1616 * In the unlikely event that someone removed it in the
1617 * meantime, we'll just come back here and read it again.
1618 */
1619 if (error >= 0)
1620 goto retry_find;
1621
1622 /*
1623 * An error return from page_cache_read can result if the
1624 * system is low on memory, or a problem occurs while trying
1625 * to schedule I/O.
1626 */
1627 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001628 return VM_FAULT_OOM;
1629 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630
1631page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 /*
1633 * Umm, take care of errors if the page isn't up-to-date.
1634 * Try to re-read it _once_. We do this synchronously,
1635 * because there really aren't any performance issues here
1636 * and we need to check for errors.
1637 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001639 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001640 if (!error) {
1641 wait_on_page_locked(page);
1642 if (!PageUptodate(page))
1643 error = -EIO;
1644 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001646
1647 if (!error || error == AOP_TRUNCATED_PAGE)
1648 goto retry_find;
1649
1650 /* Things didn't work out. Return zero to tell the mm layer so. */
1651 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001652 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001653}
1654EXPORT_SYMBOL(filemap_fault);
1655
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04001656const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001657 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658};
1659
1660/* This is used for a general mmap of a disk file */
1661
1662int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1663{
1664 struct address_space *mapping = file->f_mapping;
1665
1666 if (!mapping->a_ops->readpage)
1667 return -ENOEXEC;
1668 file_accessed(file);
1669 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001670 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001671 return 0;
1672}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673
1674/*
1675 * This is for filesystems which do not implement ->writepage.
1676 */
1677int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1678{
1679 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1680 return -EINVAL;
1681 return generic_file_mmap(file, vma);
1682}
1683#else
1684int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1685{
1686 return -ENOSYS;
1687}
1688int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1689{
1690 return -ENOSYS;
1691}
1692#endif /* CONFIG_MMU */
1693
1694EXPORT_SYMBOL(generic_file_mmap);
1695EXPORT_SYMBOL(generic_file_readonly_mmap);
1696
Nick Piggin6fe69002007-05-06 14:49:04 -07001697static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001698 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001700 void *data,
1701 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702{
Nick Piggineb2be182007-10-16 01:24:57 -07001703 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 int err;
1705repeat:
1706 page = find_get_page(mapping, index);
1707 if (!page) {
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001708 page = __page_cache_alloc(gfp | __GFP_COLD);
Nick Piggineb2be182007-10-16 01:24:57 -07001709 if (!page)
1710 return ERR_PTR(-ENOMEM);
1711 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1712 if (unlikely(err)) {
1713 page_cache_release(page);
1714 if (err == -EEXIST)
1715 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 return ERR_PTR(err);
1718 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001719 err = filler(data, page);
1720 if (err < 0) {
1721 page_cache_release(page);
1722 page = ERR_PTR(err);
1723 }
1724 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 return page;
1726}
1727
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001728static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001729 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001731 void *data,
1732 gfp_t gfp)
1733
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734{
1735 struct page *page;
1736 int err;
1737
1738retry:
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001739 page = __read_cache_page(mapping, index, filler, data, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001740 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001741 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 if (PageUptodate(page))
1743 goto out;
1744
1745 lock_page(page);
1746 if (!page->mapping) {
1747 unlock_page(page);
1748 page_cache_release(page);
1749 goto retry;
1750 }
1751 if (PageUptodate(page)) {
1752 unlock_page(page);
1753 goto out;
1754 }
1755 err = filler(data, page);
1756 if (err < 0) {
1757 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001758 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 }
David Howellsc855ff32007-05-09 13:42:20 +01001760out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001761 mark_page_accessed(page);
1762 return page;
1763}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001764
1765/**
1766 * read_cache_page_async - read into page cache, fill it if needed
1767 * @mapping: the page's address_space
1768 * @index: the page index
1769 * @filler: function to perform the read
1770 * @data: destination for read data
1771 *
1772 * Same as read_cache_page, but don't wait for page to become unlocked
1773 * after submitting it to the filler.
1774 *
1775 * Read into the page cache. If a page already exists, and PageUptodate() is
1776 * not set, try to fill the page but don't wait for it to become unlocked.
1777 *
1778 * If the page does not get brought uptodate, return -EIO.
1779 */
1780struct page *read_cache_page_async(struct address_space *mapping,
1781 pgoff_t index,
1782 int (*filler)(void *,struct page*),
1783 void *data)
1784{
1785 return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
1786}
Nick Piggin6fe69002007-05-06 14:49:04 -07001787EXPORT_SYMBOL(read_cache_page_async);
1788
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001789static struct page *wait_on_page_read(struct page *page)
1790{
1791 if (!IS_ERR(page)) {
1792 wait_on_page_locked(page);
1793 if (!PageUptodate(page)) {
1794 page_cache_release(page);
1795 page = ERR_PTR(-EIO);
1796 }
1797 }
1798 return page;
1799}
1800
1801/**
1802 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
1803 * @mapping: the page's address_space
1804 * @index: the page index
1805 * @gfp: the page allocator flags to use if allocating
1806 *
1807 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
1808 * any new page allocations done using the specified allocation flags. Note
1809 * that the Radix tree operations will still use GFP_KERNEL, so you can't
1810 * expect to do this atomically or anything like that - but you can pass in
1811 * other page requirements.
1812 *
1813 * If the page does not get brought uptodate, return -EIO.
1814 */
1815struct page *read_cache_page_gfp(struct address_space *mapping,
1816 pgoff_t index,
1817 gfp_t gfp)
1818{
1819 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
1820
1821 return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp));
1822}
1823EXPORT_SYMBOL(read_cache_page_gfp);
1824
Nick Piggin6fe69002007-05-06 14:49:04 -07001825/**
1826 * read_cache_page - read into page cache, fill it if needed
1827 * @mapping: the page's address_space
1828 * @index: the page index
1829 * @filler: function to perform the read
1830 * @data: destination for read data
1831 *
1832 * Read into the page cache. If a page already exists, and PageUptodate() is
1833 * not set, try to fill the page then wait for it to become unlocked.
1834 *
1835 * If the page does not get brought uptodate, return -EIO.
1836 */
1837struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001838 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001839 int (*filler)(void *,struct page*),
1840 void *data)
1841{
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001842 return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844EXPORT_SYMBOL(read_cache_page);
1845
1846/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847 * The logic we want is
1848 *
1849 * if suid or (sgid and xgrp)
1850 * remove privs
1851 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001852int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853{
1854 mode_t mode = dentry->d_inode->i_mode;
1855 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856
1857 /* suid always must be killed */
1858 if (unlikely(mode & S_ISUID))
1859 kill = ATTR_KILL_SUID;
1860
1861 /*
1862 * sgid without any exec bits is just a mandatory locking mark; leave
1863 * it alone. If some exec bits are set, it's a real sgid; kill it.
1864 */
1865 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1866 kill |= ATTR_KILL_SGID;
1867
Dmitri Monakhov7f5ff762008-12-01 14:34:56 -08001868 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
Jens Axboe01de85e2006-10-17 19:50:36 +02001869 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870
Jens Axboe01de85e2006-10-17 19:50:36 +02001871 return 0;
1872}
Mark Fashehd23a1472006-10-17 17:05:18 -07001873EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001874
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +02001875static int __remove_suid(struct dentry *dentry, int kill)
Jens Axboe01de85e2006-10-17 19:50:36 +02001876{
1877 struct iattr newattrs;
1878
1879 newattrs.ia_valid = ATTR_FORCE | kill;
1880 return notify_change(dentry, &newattrs);
1881}
1882
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001883int file_remove_suid(struct file *file)
Jens Axboe01de85e2006-10-17 19:50:36 +02001884{
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001885 struct dentry *dentry = file->f_path.dentry;
Serge E. Hallynb5376772007-10-16 23:31:36 -07001886 int killsuid = should_remove_suid(dentry);
1887 int killpriv = security_inode_need_killpriv(dentry);
1888 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001889
Serge E. Hallynb5376772007-10-16 23:31:36 -07001890 if (killpriv < 0)
1891 return killpriv;
1892 if (killpriv)
1893 error = security_inode_killpriv(dentry);
1894 if (!error && killsuid)
1895 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001896
Serge E. Hallynb5376772007-10-16 23:31:36 -07001897 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898}
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001899EXPORT_SYMBOL(file_remove_suid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001900
Nick Piggin2f718ff2007-10-16 01:24:59 -07001901static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001902 const struct iovec *iov, size_t base, size_t bytes)
1903{
Ingo Molnarf1800532009-03-02 11:00:57 +01001904 size_t copied = 0, left = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905
1906 while (bytes) {
1907 char __user *buf = iov->iov_base + base;
1908 int copy = min(bytes, iov->iov_len - base);
1909
1910 base = 0;
Ingo Molnarf1800532009-03-02 11:00:57 +01001911 left = __copy_from_user_inatomic(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 copied += copy;
1913 bytes -= copy;
1914 vaddr += copy;
1915 iov++;
1916
NeilBrown01408c42006-06-25 05:47:58 -07001917 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001918 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 }
1920 return copied - left;
1921}
1922
1923/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001924 * Copy as much as we can into the page and return the number of bytes which
André Goddard Rosaaf901ca2009-11-14 13:09:05 -02001925 * were successfully copied. If a fault is encountered then return the number of
Nick Piggin2f718ff2007-10-16 01:24:59 -07001926 * bytes which were copied.
1927 */
1928size_t iov_iter_copy_from_user_atomic(struct page *page,
1929 struct iov_iter *i, unsigned long offset, size_t bytes)
1930{
1931 char *kaddr;
1932 size_t copied;
1933
1934 BUG_ON(!in_atomic());
1935 kaddr = kmap_atomic(page, KM_USER0);
1936 if (likely(i->nr_segs == 1)) {
1937 int left;
1938 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001939 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001940 copied = bytes - left;
1941 } else {
1942 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1943 i->iov, i->iov_offset, bytes);
1944 }
1945 kunmap_atomic(kaddr, KM_USER0);
1946
1947 return copied;
1948}
Nick Piggin89e10782007-10-16 01:25:07 -07001949EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001950
1951/*
1952 * This has the same sideeffects and return value as
1953 * iov_iter_copy_from_user_atomic().
1954 * The difference is that it attempts to resolve faults.
1955 * Page must not be locked.
1956 */
1957size_t iov_iter_copy_from_user(struct page *page,
1958 struct iov_iter *i, unsigned long offset, size_t bytes)
1959{
1960 char *kaddr;
1961 size_t copied;
1962
1963 kaddr = kmap(page);
1964 if (likely(i->nr_segs == 1)) {
1965 int left;
1966 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001967 left = __copy_from_user(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001968 copied = bytes - left;
1969 } else {
1970 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1971 i->iov, i->iov_offset, bytes);
1972 }
1973 kunmap(page);
1974 return copied;
1975}
Nick Piggin89e10782007-10-16 01:25:07 -07001976EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001977
Nick Pigginf7009262008-03-10 11:43:59 -07001978void iov_iter_advance(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001979{
Nick Pigginf7009262008-03-10 11:43:59 -07001980 BUG_ON(i->count < bytes);
1981
Nick Piggin2f718ff2007-10-16 01:24:59 -07001982 if (likely(i->nr_segs == 1)) {
1983 i->iov_offset += bytes;
Nick Pigginf7009262008-03-10 11:43:59 -07001984 i->count -= bytes;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001985 } else {
1986 const struct iovec *iov = i->iov;
1987 size_t base = i->iov_offset;
1988
Nick Piggin124d3b72008-02-02 15:01:17 +01001989 /*
1990 * The !iov->iov_len check ensures we skip over unlikely
Nick Pigginf7009262008-03-10 11:43:59 -07001991 * zero-length segments (without overruning the iovec).
Nick Piggin124d3b72008-02-02 15:01:17 +01001992 */
Linus Torvalds94ad3742008-07-30 14:45:12 -07001993 while (bytes || unlikely(i->count && !iov->iov_len)) {
Nick Pigginf7009262008-03-10 11:43:59 -07001994 int copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001995
Nick Pigginf7009262008-03-10 11:43:59 -07001996 copy = min(bytes, iov->iov_len - base);
1997 BUG_ON(!i->count || i->count < copy);
1998 i->count -= copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001999 bytes -= copy;
2000 base += copy;
2001 if (iov->iov_len == base) {
2002 iov++;
2003 base = 0;
2004 }
2005 }
2006 i->iov = iov;
2007 i->iov_offset = base;
2008 }
2009}
Nick Piggin89e10782007-10-16 01:25:07 -07002010EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002011
Nick Pigginafddba42007-10-16 01:25:01 -07002012/*
2013 * Fault in the first iovec of the given iov_iter, to a maximum length
2014 * of bytes. Returns 0 on success, or non-zero if the memory could not be
2015 * accessed (ie. because it is an invalid address).
2016 *
2017 * writev-intensive code may want this to prefault several iovecs -- that
2018 * would be possible (callers must not rely on the fact that _only_ the
2019 * first iovec will be faulted with the current implementation).
2020 */
2021int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07002022{
Nick Piggin2f718ff2007-10-16 01:24:59 -07002023 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07002024 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
2025 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002026}
Nick Piggin89e10782007-10-16 01:25:07 -07002027EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002028
2029/*
2030 * Return the count of just the current iov_iter segment.
2031 */
2032size_t iov_iter_single_seg_count(struct iov_iter *i)
2033{
2034 const struct iovec *iov = i->iov;
2035 if (i->nr_segs == 1)
2036 return i->count;
2037 else
2038 return min(i->count, iov->iov_len - i->iov_offset);
2039}
Nick Piggin89e10782007-10-16 01:25:07 -07002040EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002041
2042/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 * Performs necessary checks before doing a write
2044 *
Randy Dunlap485bb992006-06-23 02:03:49 -07002045 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002046 * Returns appropriate error code that caller should return or
2047 * zero in case that write should be allowed.
2048 */
2049inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
2050{
2051 struct inode *inode = file->f_mapping->host;
Jiri Slaby59e99e52010-03-05 13:41:44 -08002052 unsigned long limit = rlimit(RLIMIT_FSIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053
2054 if (unlikely(*pos < 0))
2055 return -EINVAL;
2056
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057 if (!isblk) {
2058 /* FIXME: this is for backwards compatibility with 2.4 */
2059 if (file->f_flags & O_APPEND)
2060 *pos = i_size_read(inode);
2061
2062 if (limit != RLIM_INFINITY) {
2063 if (*pos >= limit) {
2064 send_sig(SIGXFSZ, current, 0);
2065 return -EFBIG;
2066 }
2067 if (*count > limit - (typeof(limit))*pos) {
2068 *count = limit - (typeof(limit))*pos;
2069 }
2070 }
2071 }
2072
2073 /*
2074 * LFS rule
2075 */
2076 if (unlikely(*pos + *count > MAX_NON_LFS &&
2077 !(file->f_flags & O_LARGEFILE))) {
2078 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002079 return -EFBIG;
2080 }
2081 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2082 *count = MAX_NON_LFS - (unsigned long)*pos;
2083 }
2084 }
2085
2086 /*
2087 * Are we about to exceed the fs block limit ?
2088 *
2089 * If we have written data it becomes a short write. If we have
2090 * exceeded without writing data we send a signal and return EFBIG.
2091 * Linus frestrict idea will clean these up nicely..
2092 */
2093 if (likely(!isblk)) {
2094 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2095 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096 return -EFBIG;
2097 }
2098 /* zero-length writes at ->s_maxbytes are OK */
2099 }
2100
2101 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2102 *count = inode->i_sb->s_maxbytes - *pos;
2103 } else {
David Howells93614012006-09-30 20:45:40 +02002104#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105 loff_t isize;
2106 if (bdev_read_only(I_BDEV(inode)))
2107 return -EPERM;
2108 isize = i_size_read(inode);
2109 if (*pos >= isize) {
2110 if (*count || *pos > isize)
2111 return -ENOSPC;
2112 }
2113
2114 if (*pos + *count > isize)
2115 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002116#else
2117 return -EPERM;
2118#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002119 }
2120 return 0;
2121}
2122EXPORT_SYMBOL(generic_write_checks);
2123
Nick Pigginafddba42007-10-16 01:25:01 -07002124int pagecache_write_begin(struct file *file, struct address_space *mapping,
2125 loff_t pos, unsigned len, unsigned flags,
2126 struct page **pagep, void **fsdata)
2127{
2128 const struct address_space_operations *aops = mapping->a_ops;
2129
Nick Piggin4e02ed42008-10-29 14:00:55 -07002130 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002131 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002132}
2133EXPORT_SYMBOL(pagecache_write_begin);
2134
2135int pagecache_write_end(struct file *file, struct address_space *mapping,
2136 loff_t pos, unsigned len, unsigned copied,
2137 struct page *page, void *fsdata)
2138{
2139 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002140
Nick Piggin4e02ed42008-10-29 14:00:55 -07002141 mark_page_accessed(page);
2142 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002143}
2144EXPORT_SYMBOL(pagecache_write_end);
2145
Linus Torvalds1da177e2005-04-16 15:20:36 -07002146ssize_t
2147generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2148 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2149 size_t count, size_t ocount)
2150{
2151 struct file *file = iocb->ki_filp;
2152 struct address_space *mapping = file->f_mapping;
2153 struct inode *inode = mapping->host;
2154 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002155 size_t write_len;
2156 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002157
2158 if (count != ocount)
2159 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2160
Christoph Hellwiga969e902008-07-23 21:27:04 -07002161 write_len = iov_length(iov, *nr_segs);
2162 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002163
Nick Piggin48b47c52009-01-06 14:40:22 -08002164 written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002165 if (written)
2166 goto out;
2167
2168 /*
2169 * After a write we want buffered reads to be sure to go to disk to get
2170 * the new data. We invalidate clean cached page from the region we're
2171 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002172 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002173 */
2174 if (mapping->nrpages) {
2175 written = invalidate_inode_pages2_range(mapping,
2176 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002177 /*
2178 * If a page can not be invalidated, return 0 to fall back
2179 * to buffered write.
2180 */
2181 if (written) {
2182 if (written == -EBUSY)
2183 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002184 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002185 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002186 }
2187
2188 written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2189
2190 /*
2191 * Finally, try again to invalidate clean pages which might have been
2192 * cached by non-direct readahead, or faulted in by get_user_pages()
2193 * if the source of the write was an mmap'ed region of the file
2194 * we're writing. Either one is a pretty crazy thing to do,
2195 * so we don't support it 100%. If this invalidation
2196 * fails, tough, the write still worked...
2197 */
2198 if (mapping->nrpages) {
2199 invalidate_inode_pages2_range(mapping,
2200 pos >> PAGE_CACHE_SHIFT, end);
2201 }
2202
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 if (written > 0) {
Namhyung Kim01166512010-10-26 14:21:58 -07002204 pos += written;
2205 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2206 i_size_write(inode, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 mark_inode_dirty(inode);
2208 }
Namhyung Kim01166512010-10-26 14:21:58 -07002209 *ppos = pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002211out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212 return written;
2213}
2214EXPORT_SYMBOL(generic_file_direct_write);
2215
Nick Piggineb2be182007-10-16 01:24:57 -07002216/*
2217 * Find or create a page at the given pagecache position. Return the locked
2218 * page. This function is specifically for buffered writes.
2219 */
Nick Piggin54566b22009-01-04 12:00:53 -08002220struct page *grab_cache_page_write_begin(struct address_space *mapping,
2221 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07002222{
2223 int status;
2224 struct page *page;
Nick Piggin54566b22009-01-04 12:00:53 -08002225 gfp_t gfp_notmask = 0;
2226 if (flags & AOP_FLAG_NOFS)
2227 gfp_notmask = __GFP_FS;
Nick Piggineb2be182007-10-16 01:24:57 -07002228repeat:
2229 page = find_lock_page(mapping, index);
Steven Rostedtc585a262011-01-13 15:46:18 -08002230 if (page)
Nick Piggineb2be182007-10-16 01:24:57 -07002231 return page;
2232
Nick Piggin54566b22009-01-04 12:00:53 -08002233 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002234 if (!page)
2235 return NULL;
Nick Piggin54566b22009-01-04 12:00:53 -08002236 status = add_to_page_cache_lru(page, mapping, index,
2237 GFP_KERNEL & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002238 if (unlikely(status)) {
2239 page_cache_release(page);
2240 if (status == -EEXIST)
2241 goto repeat;
2242 return NULL;
2243 }
2244 return page;
2245}
Nick Piggin54566b22009-01-04 12:00:53 -08002246EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07002247
Nick Pigginafddba42007-10-16 01:25:01 -07002248static ssize_t generic_perform_write(struct file *file,
2249 struct iov_iter *i, loff_t pos)
2250{
2251 struct address_space *mapping = file->f_mapping;
2252 const struct address_space_operations *a_ops = mapping->a_ops;
2253 long status = 0;
2254 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002255 unsigned int flags = 0;
2256
2257 /*
2258 * Copies from kernel address space cannot fail (NFSD is a big user).
2259 */
2260 if (segment_eq(get_fs(), KERNEL_DS))
2261 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002262
2263 do {
2264 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07002265 unsigned long offset; /* Offset into pagecache page */
2266 unsigned long bytes; /* Bytes to write to page */
2267 size_t copied; /* Bytes copied from user */
2268 void *fsdata;
2269
2270 offset = (pos & (PAGE_CACHE_SIZE - 1));
Nick Pigginafddba42007-10-16 01:25:01 -07002271 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2272 iov_iter_count(i));
2273
2274again:
2275
2276 /*
2277 * Bring in the user page that we will copy from _first_.
2278 * Otherwise there's a nasty deadlock on copying from the
2279 * same page as we're writing to, without it being marked
2280 * up-to-date.
2281 *
2282 * Not only is this an optimisation, but it is also required
2283 * to check that the address is actually valid, when atomic
2284 * usercopies are used, below.
2285 */
2286 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2287 status = -EFAULT;
2288 break;
2289 }
2290
Nick Piggin674b8922007-10-16 01:25:03 -07002291 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002292 &page, &fsdata);
2293 if (unlikely(status))
2294 break;
2295
anfei zhou931e80e2010-02-02 13:44:02 -08002296 if (mapping_writably_mapped(mapping))
2297 flush_dcache_page(page);
2298
Nick Pigginafddba42007-10-16 01:25:01 -07002299 pagefault_disable();
2300 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2301 pagefault_enable();
2302 flush_dcache_page(page);
2303
Josef Bacikc8236db2009-07-05 12:08:18 -07002304 mark_page_accessed(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002305 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2306 page, fsdata);
2307 if (unlikely(status < 0))
2308 break;
2309 copied = status;
2310
2311 cond_resched();
2312
Nick Piggin124d3b72008-02-02 15:01:17 +01002313 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002314 if (unlikely(copied == 0)) {
2315 /*
2316 * If we were unable to copy any data at all, we must
2317 * fall back to a single segment length write.
2318 *
2319 * If we didn't fallback here, we could livelock
2320 * because not all segments in the iov can be copied at
2321 * once without a pagefault.
2322 */
2323 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2324 iov_iter_single_seg_count(i));
2325 goto again;
2326 }
Nick Pigginafddba42007-10-16 01:25:01 -07002327 pos += copied;
2328 written += copied;
2329
2330 balance_dirty_pages_ratelimited(mapping);
2331
2332 } while (iov_iter_count(i));
2333
2334 return written ? written : status;
2335}
2336
2337ssize_t
2338generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2339 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2340 size_t count, ssize_t written)
2341{
2342 struct file *file = iocb->ki_filp;
Nick Pigginafddba42007-10-16 01:25:01 -07002343 ssize_t status;
2344 struct iov_iter i;
2345
2346 iov_iter_init(&i, iov, nr_segs, count, written);
Nick Piggin4e02ed42008-10-29 14:00:55 -07002347 status = generic_perform_write(file, &i, pos);
Nick Pigginafddba42007-10-16 01:25:01 -07002348
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002350 written += status;
2351 *ppos = pos + status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352 }
2353
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354 return written ? written : status;
2355}
2356EXPORT_SYMBOL(generic_file_buffered_write);
2357
Jan Karae4dd9de2009-08-17 18:10:06 +02002358/**
2359 * __generic_file_aio_write - write data to a file
2360 * @iocb: IO state structure (file, offset, etc.)
2361 * @iov: vector with data to write
2362 * @nr_segs: number of segments in the vector
2363 * @ppos: position where to write
2364 *
2365 * This function does all the work needed for actually writing data to a
2366 * file. It does all basic checks, removes SUID from the file, updates
2367 * modification times and calls proper subroutines depending on whether we
2368 * do direct IO or a standard buffered write.
2369 *
2370 * It expects i_mutex to be grabbed unless we work on a block device or similar
2371 * object which does not need locking at all.
2372 *
2373 * This function does *not* take care of syncing data in case of O_SYNC write.
2374 * A caller has to handle it. This is mainly due to the fact that we want to
2375 * avoid syncing under i_mutex.
2376 */
2377ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2378 unsigned long nr_segs, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002379{
2380 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002381 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002382 size_t ocount; /* original count */
2383 size_t count; /* after file limit checks */
2384 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385 loff_t pos;
2386 ssize_t written;
2387 ssize_t err;
2388
2389 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002390 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2391 if (err)
2392 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393
2394 count = ocount;
2395 pos = *ppos;
2396
2397 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2398
2399 /* We can write back this queue in page reclaim */
2400 current->backing_dev_info = mapping->backing_dev_info;
2401 written = 0;
2402
2403 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2404 if (err)
2405 goto out;
2406
2407 if (count == 0)
2408 goto out;
2409
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002410 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411 if (err)
2412 goto out;
2413
Christoph Hellwig870f4812006-01-09 20:52:01 -08002414 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415
2416 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2417 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002418 loff_t endbyte;
2419 ssize_t written_buffered;
2420
2421 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2422 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423 if (written < 0 || written == count)
2424 goto out;
2425 /*
2426 * direct-io write to a hole: fall through to buffered I/O
2427 * for completing the rest of the request.
2428 */
2429 pos += written;
2430 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002431 written_buffered = generic_file_buffered_write(iocb, iov,
2432 nr_segs, pos, ppos, count,
2433 written);
2434 /*
2435 * If generic_file_buffered_write() retuned a synchronous error
2436 * then we want to return the number of bytes which were
2437 * direct-written, or the error code if that was zero. Note
2438 * that this differs from normal direct-io semantics, which
2439 * will return -EFOO even if some bytes were written.
2440 */
2441 if (written_buffered < 0) {
2442 err = written_buffered;
2443 goto out;
2444 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002446 /*
2447 * We need to ensure that the page cache pages are written to
2448 * disk and invalidated to preserve the expected O_DIRECT
2449 * semantics.
2450 */
2451 endbyte = pos + written_buffered - written - 1;
Christoph Hellwigc05c4ed2009-09-23 15:07:30 +02002452 err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002453 if (err == 0) {
2454 written = written_buffered;
2455 invalidate_mapping_pages(mapping,
2456 pos >> PAGE_CACHE_SHIFT,
2457 endbyte >> PAGE_CACHE_SHIFT);
2458 } else {
2459 /*
2460 * We don't know how much we wrote, so just return
2461 * the number of bytes which were direct-written
2462 */
2463 }
2464 } else {
2465 written = generic_file_buffered_write(iocb, iov, nr_segs,
2466 pos, ppos, count, written);
2467 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002468out:
2469 current->backing_dev_info = NULL;
2470 return written ? written : err;
2471}
Jan Karae4dd9de2009-08-17 18:10:06 +02002472EXPORT_SYMBOL(__generic_file_aio_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473
Jan Karae4dd9de2009-08-17 18:10:06 +02002474/**
2475 * generic_file_aio_write - write data to a file
2476 * @iocb: IO state structure
2477 * @iov: vector with data to write
2478 * @nr_segs: number of segments in the vector
2479 * @pos: position in file where to write
2480 *
2481 * This is a wrapper around __generic_file_aio_write() to be used by most
2482 * filesystems. It takes care of syncing the file in case of O_SYNC file
2483 * and acquires i_mutex as needed.
2484 */
Badari Pulavarty027445c2006-09-30 23:28:46 -07002485ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2486 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487{
2488 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02002489 struct inode *inode = file->f_mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002490 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002491
2492 BUG_ON(iocb->ki_pos != pos);
2493
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002494 mutex_lock(&inode->i_mutex);
Jan Karae4dd9de2009-08-17 18:10:06 +02002495 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002496 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497
Jan Kara148f9482009-08-17 19:52:36 +02002498 if (ret > 0 || ret == -EIOCBQUEUED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002499 ssize_t err;
2500
Jan Kara148f9482009-08-17 19:52:36 +02002501 err = generic_write_sync(file, pos, ret);
Jan Karac7b50db2009-08-18 16:18:20 +02002502 if (err < 0 && ret > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002503 ret = err;
2504 }
2505 return ret;
2506}
2507EXPORT_SYMBOL(generic_file_aio_write);
2508
David Howellscf9a2ae2006-08-29 19:05:54 +01002509/**
2510 * try_to_release_page() - release old fs-specific metadata on a page
2511 *
2512 * @page: the page which the kernel is trying to free
2513 * @gfp_mask: memory allocation flags (and I/O mode)
2514 *
2515 * The address_space is to try to release any data against the page
2516 * (presumably at page->private). If the release was successful, return `1'.
2517 * Otherwise return zero.
2518 *
David Howells266cf652009-04-03 16:42:36 +01002519 * This may also be called if PG_fscache is set on a page, indicating that the
2520 * page is known to the local caching routines.
2521 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002522 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fdd2008-07-25 01:46:22 -07002523 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002524 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002525 */
2526int try_to_release_page(struct page *page, gfp_t gfp_mask)
2527{
2528 struct address_space * const mapping = page->mapping;
2529
2530 BUG_ON(!PageLocked(page));
2531 if (PageWriteback(page))
2532 return 0;
2533
2534 if (mapping && mapping->a_ops->releasepage)
2535 return mapping->a_ops->releasepage(page, gfp_mask);
2536 return try_to_free_buffers(page);
2537}
2538
2539EXPORT_SYMBOL(try_to_release_page);