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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 *
105 * ->task->proc_lock
106 * ->dcache_lock (proc_pid_lookup)
Andi Kleen6a460792009-09-16 11:50:15 +0200107 *
108 * (code doesn't rely on that order, so you could switch it around)
109 * ->tasklist_lock (memory_failure, collect_procs_ao)
110 * ->i_mmap_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 */
112
113/*
114 * Remove a page from the page cache and free it. Caller has to make
115 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700116 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 */
118void __remove_from_page_cache(struct page *page)
119{
120 struct address_space *mapping = page->mapping;
121
122 radix_tree_delete(&mapping->page_tree, page->index);
123 page->mapping = NULL;
124 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700125 __dec_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700126 if (PageSwapBacked(page))
127 __dec_zone_page_state(page, NR_SHMEM);
Nick Piggin45426812007-07-15 23:38:12 -0700128 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800129
130 /*
131 * Some filesystems seem to re-dirty the page even after
132 * the VM has canceled the dirty bit (eg ext3 journaling).
133 *
134 * Fix it up by doing a final dirty accounting check after
135 * having removed the page entirely.
136 */
137 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
138 dec_zone_page_state(page, NR_FILE_DIRTY);
139 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
140 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141}
142
143void remove_from_page_cache(struct page *page)
144{
145 struct address_space *mapping = page->mapping;
Linus Torvalds6072d132010-12-01 13:35:19 -0500146 void (*freepage)(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
Matt Mackallcd7619d2005-05-01 08:59:01 -0700148 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
Linus Torvalds6072d132010-12-01 13:35:19 -0500150 freepage = mapping->a_ops->freepage;
Nick Piggin19fd6232008-07-25 19:45:32 -0700151 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 __remove_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700153 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700154 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500155
156 if (freepage)
157 freepage(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158}
Miklos Szeredia52116a2010-05-25 15:06:06 +0200159EXPORT_SYMBOL(remove_from_page_cache);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160
161static int sync_page(void *word)
162{
163 struct address_space *mapping;
164 struct page *page;
165
Andi Kleen07808b72005-11-05 17:25:53 +0100166 page = container_of((unsigned long *)word, struct page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167
168 /*
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700169 * page_mapping() is being called without PG_locked held.
170 * Some knowledge of the state and use of the page is used to
171 * reduce the requirements down to a memory barrier.
172 * The danger here is of a stale page_mapping() return value
173 * indicating a struct address_space different from the one it's
174 * associated with when it is associated with one.
175 * After smp_mb(), it's either the correct page_mapping() for
176 * the page, or an old page_mapping() and the page's own
177 * page_mapping() has gone NULL.
178 * The ->sync_page() address_space operation must tolerate
179 * page_mapping() going NULL. By an amazing coincidence,
180 * this comes about because none of the users of the page
181 * in the ->sync_page() methods make essential use of the
182 * page_mapping(), merely passing the page down to the backing
183 * device's unplug functions when it's non-NULL, which in turn
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700184 * ignore it for all cases but swap, where only page_private(page) is
William Lee Irwin IIIdd1d5af2005-05-01 08:58:38 -0700185 * of interest. When page_mapping() does go NULL, the entire
186 * call stack gracefully ignores the page and returns.
187 * -- wli
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 */
189 smp_mb();
190 mapping = page_mapping(page);
191 if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
192 mapping->a_ops->sync_page(page);
193 io_schedule();
194 return 0;
195}
196
Matthew Wilcox2687a352007-12-06 11:18:49 -0500197static int sync_page_killable(void *word)
198{
199 sync_page(word);
200 return fatal_signal_pending(current) ? -EINTR : 0;
201}
202
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700204 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700205 * @mapping: address space structure to write
206 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800207 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700208 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700210 * Start writeback against all of a mapping's dirty pages that lie
211 * within the byte offsets <start, end> inclusive.
212 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700214 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 * these two operations is that if a dirty page/buffer is encountered, it must
216 * be waited upon, and not just skipped over.
217 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800218int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
219 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220{
221 int ret;
222 struct writeback_control wbc = {
223 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800224 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700225 .range_start = start,
226 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 };
228
229 if (!mapping_cap_writeback_dirty(mapping))
230 return 0;
231
232 ret = do_writepages(mapping, &wbc);
233 return ret;
234}
235
236static inline int __filemap_fdatawrite(struct address_space *mapping,
237 int sync_mode)
238{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700239 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240}
241
242int filemap_fdatawrite(struct address_space *mapping)
243{
244 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
245}
246EXPORT_SYMBOL(filemap_fdatawrite);
247
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400248int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800249 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250{
251 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
252}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400253EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254
Randy Dunlap485bb992006-06-23 02:03:49 -0700255/**
256 * filemap_flush - mostly a non-blocking flush
257 * @mapping: target address_space
258 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 * This is a mostly non-blocking flush. Not suitable for data-integrity
260 * purposes - I/O may not be started against all dirty pages.
261 */
262int filemap_flush(struct address_space *mapping)
263{
264 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
265}
266EXPORT_SYMBOL(filemap_flush);
267
Randy Dunlap485bb992006-06-23 02:03:49 -0700268/**
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200269 * filemap_fdatawait_range - wait for writeback to complete
270 * @mapping: address space structure to wait for
271 * @start_byte: offset in bytes where the range starts
272 * @end_byte: offset in bytes where the range ends (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -0700273 *
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200274 * Walk the list of under-writeback pages of the given address space
275 * in the given range and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 */
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200277int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
278 loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279{
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200280 pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
281 pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 struct pagevec pvec;
283 int nr_pages;
284 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200286 if (end_byte < start_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 return 0;
288
289 pagevec_init(&pvec, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 while ((index <= end) &&
291 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
292 PAGECACHE_TAG_WRITEBACK,
293 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
294 unsigned i;
295
296 for (i = 0; i < nr_pages; i++) {
297 struct page *page = pvec.pages[i];
298
299 /* until radix tree lookup accepts end_index */
300 if (page->index > end)
301 continue;
302
303 wait_on_page_writeback(page);
304 if (PageError(page))
305 ret = -EIO;
306 }
307 pagevec_release(&pvec);
308 cond_resched();
309 }
310
311 /* Check for outstanding write errors */
312 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
313 ret = -ENOSPC;
314 if (test_and_clear_bit(AS_EIO, &mapping->flags))
315 ret = -EIO;
316
317 return ret;
318}
Jan Karad3bccb6f2009-08-17 19:30:27 +0200319EXPORT_SYMBOL(filemap_fdatawait_range);
320
321/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700322 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700324 *
325 * Walk the list of under-writeback pages of the given address space
326 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 */
328int filemap_fdatawait(struct address_space *mapping)
329{
330 loff_t i_size = i_size_read(mapping->host);
331
332 if (i_size == 0)
333 return 0;
334
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200335 return filemap_fdatawait_range(mapping, 0, i_size - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336}
337EXPORT_SYMBOL(filemap_fdatawait);
338
339int filemap_write_and_wait(struct address_space *mapping)
340{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800341 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342
343 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800344 err = filemap_fdatawrite(mapping);
345 /*
346 * Even if the above returned error, the pages may be
347 * written partially (e.g. -ENOSPC), so we wait for it.
348 * But the -EIO is special case, it may indicate the worst
349 * thing (e.g. bug) happened, so we avoid waiting for it.
350 */
351 if (err != -EIO) {
352 int err2 = filemap_fdatawait(mapping);
353 if (!err)
354 err = err2;
355 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800357 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800359EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360
Randy Dunlap485bb992006-06-23 02:03:49 -0700361/**
362 * filemap_write_and_wait_range - write out & wait on a file range
363 * @mapping: the address_space for the pages
364 * @lstart: offset in bytes where the range starts
365 * @lend: offset in bytes where the range ends (inclusive)
366 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800367 * Write out and wait upon file offsets lstart->lend, inclusive.
368 *
369 * Note that `lend' is inclusive (describes the last byte to be written) so
370 * that this function can be used to write to the very end-of-file (end = -1).
371 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372int filemap_write_and_wait_range(struct address_space *mapping,
373 loff_t lstart, loff_t lend)
374{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800375 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800378 err = __filemap_fdatawrite_range(mapping, lstart, lend,
379 WB_SYNC_ALL);
380 /* See comment of filemap_write_and_wait() */
381 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200382 int err2 = filemap_fdatawait_range(mapping,
383 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800384 if (!err)
385 err = err2;
386 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800388 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389}
Chris Masonf6995582009-04-15 13:22:37 -0400390EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391
Randy Dunlap485bb992006-06-23 02:03:49 -0700392/**
Nick Piggine2867812008-07-25 19:45:30 -0700393 * add_to_page_cache_locked - add a locked page to the pagecache
Randy Dunlap485bb992006-06-23 02:03:49 -0700394 * @page: page to add
395 * @mapping: the page's address_space
396 * @offset: page index
397 * @gfp_mask: page allocation mode
398 *
Nick Piggine2867812008-07-25 19:45:30 -0700399 * This function is used to add a page to the pagecache. It must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 * This function does not add the page to the LRU. The caller must do that.
401 */
Nick Piggine2867812008-07-25 19:45:30 -0700402int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400403 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404{
Nick Piggine2867812008-07-25 19:45:30 -0700405 int error;
406
407 VM_BUG_ON(!PageLocked(page));
408
409 error = mem_cgroup_cache_charge(page, current->mm,
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -0800410 gfp_mask & GFP_RECLAIM_MASK);
Balbir Singh35c754d2008-02-07 00:14:05 -0800411 if (error)
412 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413
Balbir Singh35c754d2008-02-07 00:14:05 -0800414 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 if (error == 0) {
Nick Piggine2867812008-07-25 19:45:30 -0700416 page_cache_get(page);
417 page->mapping = mapping;
418 page->index = offset;
419
Nick Piggin19fd6232008-07-25 19:45:32 -0700420 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 error = radix_tree_insert(&mapping->page_tree, offset, page);
Nick Piggine2867812008-07-25 19:45:30 -0700422 if (likely(!error)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700424 __inc_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700425 if (PageSwapBacked(page))
426 __inc_zone_page_state(page, NR_SHMEM);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700427 spin_unlock_irq(&mapping->tree_lock);
Nick Piggine2867812008-07-25 19:45:30 -0700428 } else {
429 page->mapping = NULL;
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700430 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700431 mem_cgroup_uncharge_cache_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700432 page_cache_release(page);
433 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800435 } else
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700436 mem_cgroup_uncharge_cache_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800437out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 return error;
439}
Nick Piggine2867812008-07-25 19:45:30 -0700440EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441
442int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400443 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700445 int ret;
446
447 /*
448 * Splice_read and readahead add shmem/tmpfs pages into the page cache
449 * before shmem_readpage has a chance to mark them as SwapBacked: they
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700450 * need to go on the anon lru below, and mem_cgroup_cache_charge
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700451 * (called in add_to_page_cache) needs to know where they're going too.
452 */
453 if (mapping_cap_swap_backed(mapping))
454 SetPageSwapBacked(page);
455
456 ret = add_to_page_cache(page, mapping, offset, gfp_mask);
457 if (ret == 0) {
458 if (page_is_file_cache(page))
459 lru_cache_add_file(page);
460 else
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700461 lru_cache_add_anon(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700462 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 return ret;
464}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300465EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466
Paul Jackson44110fe2006-03-24 03:16:04 -0800467#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700468struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800469{
Miao Xiec0ff7452010-05-24 14:32:08 -0700470 int n;
471 struct page *page;
472
Paul Jackson44110fe2006-03-24 03:16:04 -0800473 if (cpuset_do_page_mem_spread()) {
Miao Xiec0ff7452010-05-24 14:32:08 -0700474 get_mems_allowed();
475 n = cpuset_mem_spread_node();
476 page = alloc_pages_exact_node(n, gfp, 0);
477 put_mems_allowed();
478 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800479 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700480 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800481}
Nick Piggin2ae88142006-10-28 10:38:23 -0700482EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800483#endif
484
Nick Piggindb376482006-09-25 23:31:24 -0700485static int __sleep_on_page_lock(void *word)
486{
487 io_schedule();
488 return 0;
489}
490
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491/*
492 * In order to wait for pages to become available there must be
493 * waitqueues associated with pages. By using a hash table of
494 * waitqueues where the bucket discipline is to maintain all
495 * waiters on the same queue and wake all when any of the pages
496 * become available, and for the woken contexts to check to be
497 * sure the appropriate page became available, this saves space
498 * at a cost of "thundering herd" phenomena during rare hash
499 * collisions.
500 */
501static wait_queue_head_t *page_waitqueue(struct page *page)
502{
503 const struct zone *zone = page_zone(page);
504
505 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
506}
507
508static inline void wake_up_page(struct page *page, int bit)
509{
510 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
511}
512
Harvey Harrison920c7a52008-02-04 22:29:26 -0800513void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514{
515 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
516
517 if (test_bit(bit_nr, &page->flags))
518 __wait_on_bit(page_waitqueue(page), &wait, sync_page,
519 TASK_UNINTERRUPTIBLE);
520}
521EXPORT_SYMBOL(wait_on_page_bit);
522
523/**
David Howells385e1ca5f2009-04-03 16:42:39 +0100524 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -0700525 * @page: Page defining the wait queue of interest
526 * @waiter: Waiter to add to the queue
David Howells385e1ca5f2009-04-03 16:42:39 +0100527 *
528 * Add an arbitrary @waiter to the wait queue for the nominated @page.
529 */
530void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
531{
532 wait_queue_head_t *q = page_waitqueue(page);
533 unsigned long flags;
534
535 spin_lock_irqsave(&q->lock, flags);
536 __add_wait_queue(q, waiter);
537 spin_unlock_irqrestore(&q->lock, flags);
538}
539EXPORT_SYMBOL_GPL(add_page_wait_queue);
540
541/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700542 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 * @page: the page
544 *
545 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
546 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
547 * mechananism between PageLocked pages and PageWriteback pages is shared.
548 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
549 *
Nick Piggin8413ac92008-10-18 20:26:59 -0700550 * The mb is necessary to enforce ordering between the clear_bit and the read
551 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800553void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554{
Nick Piggin8413ac92008-10-18 20:26:59 -0700555 VM_BUG_ON(!PageLocked(page));
556 clear_bit_unlock(PG_locked, &page->flags);
557 smp_mb__after_clear_bit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 wake_up_page(page, PG_locked);
559}
560EXPORT_SYMBOL(unlock_page);
561
Randy Dunlap485bb992006-06-23 02:03:49 -0700562/**
563 * end_page_writeback - end writeback against a page
564 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 */
566void end_page_writeback(struct page *page)
567{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700568 if (TestClearPageReclaim(page))
569 rotate_reclaimable_page(page);
570
571 if (!test_clear_page_writeback(page))
572 BUG();
573
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 smp_mb__after_clear_bit();
575 wake_up_page(page, PG_writeback);
576}
577EXPORT_SYMBOL(end_page_writeback);
578
Randy Dunlap485bb992006-06-23 02:03:49 -0700579/**
580 * __lock_page - get a lock on the page, assuming we need to sleep to get it
581 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700583 * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 * random driver's requestfn sets TASK_RUNNING, we could busywait. However
585 * chances are that on the second loop, the block layer's plug list is empty,
586 * so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
587 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800588void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589{
590 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
591
592 __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
593 TASK_UNINTERRUPTIBLE);
594}
595EXPORT_SYMBOL(__lock_page);
596
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800597int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500598{
599 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
600
601 return __wait_on_bit_lock(page_waitqueue(page), &wait,
602 sync_page_killable, TASK_KILLABLE);
603}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300604EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500605
Randy Dunlap76824862008-03-19 17:00:40 -0700606/**
607 * __lock_page_nosync - get a lock on the page, without calling sync_page()
608 * @page: the page to lock
609 *
Nick Piggindb376482006-09-25 23:31:24 -0700610 * Variant of lock_page that does not require the caller to hold a reference
611 * on the page's mapping.
612 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800613void __lock_page_nosync(struct page *page)
Nick Piggindb376482006-09-25 23:31:24 -0700614{
615 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
616 __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
617 TASK_UNINTERRUPTIBLE);
618}
619
Michel Lespinassed065bd82010-10-26 14:21:57 -0700620int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
621 unsigned int flags)
622{
623 if (!(flags & FAULT_FLAG_ALLOW_RETRY)) {
624 __lock_page(page);
625 return 1;
626 } else {
627 up_read(&mm->mmap_sem);
628 wait_on_page_locked(page);
629 return 0;
630 }
631}
632
Randy Dunlap485bb992006-06-23 02:03:49 -0700633/**
634 * find_get_page - find and get a page reference
635 * @mapping: the address_space to search
636 * @offset: the page index
637 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700638 * Is there a pagecache struct page at the given (mapping, offset) tuple?
639 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 */
Nick Piggina60637c2008-07-25 19:45:31 -0700641struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642{
Nick Piggina60637c2008-07-25 19:45:31 -0700643 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 struct page *page;
645
Nick Piggina60637c2008-07-25 19:45:31 -0700646 rcu_read_lock();
647repeat:
648 page = NULL;
649 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
650 if (pagep) {
651 page = radix_tree_deref_slot(pagep);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800652 if (unlikely(!page))
653 goto out;
654 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700655 goto repeat;
656
657 if (!page_cache_get_speculative(page))
658 goto repeat;
659
660 /*
661 * Has the page moved?
662 * This is part of the lockless pagecache protocol. See
663 * include/linux/pagemap.h for details.
664 */
665 if (unlikely(page != *pagep)) {
666 page_cache_release(page);
667 goto repeat;
668 }
669 }
Nick Piggin27d20fd2010-11-11 14:05:19 -0800670out:
Nick Piggina60637c2008-07-25 19:45:31 -0700671 rcu_read_unlock();
672
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 return page;
674}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675EXPORT_SYMBOL(find_get_page);
676
Randy Dunlap485bb992006-06-23 02:03:49 -0700677/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700679 * @mapping: the address_space to search
680 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681 *
682 * Locates the desired pagecache page, locks it, increments its reference
683 * count and returns its address.
684 *
685 * Returns zero if the page was not present. find_lock_page() may sleep.
686 */
Nick Piggina60637c2008-07-25 19:45:31 -0700687struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688{
689 struct page *page;
690
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691repeat:
Nick Piggina60637c2008-07-25 19:45:31 -0700692 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 if (page) {
Nick Piggina60637c2008-07-25 19:45:31 -0700694 lock_page(page);
695 /* Has the page been truncated? */
696 if (unlikely(page->mapping != mapping)) {
697 unlock_page(page);
698 page_cache_release(page);
699 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 }
Nick Piggina60637c2008-07-25 19:45:31 -0700701 VM_BUG_ON(page->index != offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 return page;
704}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705EXPORT_SYMBOL(find_lock_page);
706
707/**
708 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700709 * @mapping: the page's address_space
710 * @index: the page's index into the mapping
711 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 *
713 * Locates a page in the pagecache. If the page is not present, a new page
714 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
715 * LRU list. The returned page is locked and has its reference count
716 * incremented.
717 *
718 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
719 * allocation!
720 *
721 * find_or_create_page() returns the desired page's address, or zero on
722 * memory exhaustion.
723 */
724struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700725 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726{
Nick Piggineb2be182007-10-16 01:24:57 -0700727 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 int err;
729repeat:
730 page = find_lock_page(mapping, index);
731 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700732 page = __page_cache_alloc(gfp_mask);
733 if (!page)
734 return NULL;
Nick Piggin67d58ac2009-01-06 14:40:28 -0800735 /*
736 * We want a regular kernel memory (not highmem or DMA etc)
737 * allocation for the radix tree nodes, but we need to honour
738 * the context-specific requirements the caller has asked for.
739 * GFP_RECLAIM_MASK collects those requirements.
740 */
741 err = add_to_page_cache_lru(page, mapping, index,
742 (gfp_mask & GFP_RECLAIM_MASK));
Nick Piggineb2be182007-10-16 01:24:57 -0700743 if (unlikely(err)) {
744 page_cache_release(page);
745 page = NULL;
746 if (err == -EEXIST)
747 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 return page;
751}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752EXPORT_SYMBOL(find_or_create_page);
753
754/**
755 * find_get_pages - gang pagecache lookup
756 * @mapping: The address_space to search
757 * @start: The starting page index
758 * @nr_pages: The maximum number of pages
759 * @pages: Where the resulting pages are placed
760 *
761 * find_get_pages() will search for and return a group of up to
762 * @nr_pages pages in the mapping. The pages are placed at @pages.
763 * find_get_pages() takes a reference against the returned pages.
764 *
765 * The search returns a group of mapping-contiguous pages with ascending
766 * indexes. There may be holes in the indices due to not-present pages.
767 *
768 * find_get_pages() returns the number of pages which were found.
769 */
770unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
771 unsigned int nr_pages, struct page **pages)
772{
773 unsigned int i;
774 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700775 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776
Nick Piggina60637c2008-07-25 19:45:31 -0700777 rcu_read_lock();
778restart:
779 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
780 (void ***)pages, start, nr_pages);
781 ret = 0;
782 for (i = 0; i < nr_found; i++) {
783 struct page *page;
784repeat:
785 page = radix_tree_deref_slot((void **)pages[i]);
786 if (unlikely(!page))
787 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800788 if (radix_tree_deref_retry(page)) {
789 if (ret)
790 start = pages[ret-1]->index;
Nick Piggina60637c2008-07-25 19:45:31 -0700791 goto restart;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800792 }
Nick Piggina60637c2008-07-25 19:45:31 -0700793
794 if (!page_cache_get_speculative(page))
795 goto repeat;
796
797 /* Has the page moved? */
798 if (unlikely(page != *((void **)pages[i]))) {
799 page_cache_release(page);
800 goto repeat;
801 }
802
803 pages[ret] = page;
804 ret++;
805 }
806 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 return ret;
808}
809
Jens Axboeebf43502006-04-27 08:46:01 +0200810/**
811 * find_get_pages_contig - gang contiguous pagecache lookup
812 * @mapping: The address_space to search
813 * @index: The starting page index
814 * @nr_pages: The maximum number of pages
815 * @pages: Where the resulting pages are placed
816 *
817 * find_get_pages_contig() works exactly like find_get_pages(), except
818 * that the returned number of pages are guaranteed to be contiguous.
819 *
820 * find_get_pages_contig() returns the number of pages which were found.
821 */
822unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
823 unsigned int nr_pages, struct page **pages)
824{
825 unsigned int i;
826 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700827 unsigned int nr_found;
Jens Axboeebf43502006-04-27 08:46:01 +0200828
Nick Piggina60637c2008-07-25 19:45:31 -0700829 rcu_read_lock();
830restart:
831 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
832 (void ***)pages, index, nr_pages);
833 ret = 0;
834 for (i = 0; i < nr_found; i++) {
835 struct page *page;
836repeat:
837 page = radix_tree_deref_slot((void **)pages[i]);
838 if (unlikely(!page))
839 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800840 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700841 goto restart;
842
843 if (page->mapping == NULL || page->index != index)
Jens Axboeebf43502006-04-27 08:46:01 +0200844 break;
845
Nick Piggina60637c2008-07-25 19:45:31 -0700846 if (!page_cache_get_speculative(page))
847 goto repeat;
848
849 /* Has the page moved? */
850 if (unlikely(page != *((void **)pages[i]))) {
851 page_cache_release(page);
852 goto repeat;
853 }
854
855 pages[ret] = page;
856 ret++;
Jens Axboeebf43502006-04-27 08:46:01 +0200857 index++;
858 }
Nick Piggina60637c2008-07-25 19:45:31 -0700859 rcu_read_unlock();
860 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +0200861}
David Howellsef71c152007-05-09 02:33:44 -0700862EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200863
Randy Dunlap485bb992006-06-23 02:03:49 -0700864/**
865 * find_get_pages_tag - find and return pages that match @tag
866 * @mapping: the address_space to search
867 * @index: the starting page index
868 * @tag: the tag index
869 * @nr_pages: the maximum number of pages
870 * @pages: where the resulting pages are placed
871 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700873 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 */
875unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
876 int tag, unsigned int nr_pages, struct page **pages)
877{
878 unsigned int i;
879 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700880 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881
Nick Piggina60637c2008-07-25 19:45:31 -0700882 rcu_read_lock();
883restart:
884 nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
885 (void ***)pages, *index, nr_pages, tag);
886 ret = 0;
887 for (i = 0; i < nr_found; i++) {
888 struct page *page;
889repeat:
890 page = radix_tree_deref_slot((void **)pages[i]);
891 if (unlikely(!page))
892 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800893 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700894 goto restart;
895
896 if (!page_cache_get_speculative(page))
897 goto repeat;
898
899 /* Has the page moved? */
900 if (unlikely(page != *((void **)pages[i]))) {
901 page_cache_release(page);
902 goto repeat;
903 }
904
905 pages[ret] = page;
906 ret++;
907 }
908 rcu_read_unlock();
909
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 if (ret)
911 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -0700912
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 return ret;
914}
David Howellsef71c152007-05-09 02:33:44 -0700915EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700916
Randy Dunlap485bb992006-06-23 02:03:49 -0700917/**
918 * grab_cache_page_nowait - returns locked page at given index in given cache
919 * @mapping: target address_space
920 * @index: the page index
921 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800922 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 * This is intended for speculative data generators, where the data can
924 * be regenerated if the page couldn't be grabbed. This routine should
925 * be safe to call while holding the lock for another page.
926 *
927 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
928 * and deadlock against the caller's locked page.
929 */
930struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700931grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932{
933 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700934
935 if (page) {
Nick Piggin529ae9a2008-08-02 12:01:03 +0200936 if (trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937 return page;
938 page_cache_release(page);
939 return NULL;
940 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700941 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
Nick Piggin67d58ac2009-01-06 14:40:28 -0800942 if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943 page_cache_release(page);
944 page = NULL;
945 }
946 return page;
947}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948EXPORT_SYMBOL(grab_cache_page_nowait);
949
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700950/*
951 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
952 * a _large_ part of the i/o request. Imagine the worst scenario:
953 *
954 * ---R__________________________________________B__________
955 * ^ reading here ^ bad block(assume 4k)
956 *
957 * read(R) => miss => readahead(R...B) => media error => frustrating retries
958 * => failing the whole request => read(R) => read(R+1) =>
959 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
960 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
961 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
962 *
963 * It is going insane. Fix it by quickly scaling down the readahead size.
964 */
965static void shrink_readahead_size_eio(struct file *filp,
966 struct file_ra_state *ra)
967{
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700968 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -0700969}
970
Randy Dunlap485bb992006-06-23 02:03:49 -0700971/**
Christoph Hellwig36e78912008-02-08 04:21:24 -0800972 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -0700973 * @filp: the file to read
974 * @ppos: current file position
975 * @desc: read_descriptor
976 * @actor: read method
977 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -0700979 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980 *
981 * This is really ugly. But the goto's actually try to clarify some
982 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 */
Christoph Hellwig36e78912008-02-08 04:21:24 -0800984static void do_generic_file_read(struct file *filp, loff_t *ppos,
985 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986{
Christoph Hellwig36e78912008-02-08 04:21:24 -0800987 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -0800989 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -0700990 pgoff_t index;
991 pgoff_t last_index;
992 pgoff_t prev_index;
993 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -0700994 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -0700998 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
999 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
1001 offset = *ppos & ~PAGE_CACHE_MASK;
1002
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 for (;;) {
1004 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001005 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -07001006 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007 unsigned long nr, ret;
1008
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010find_page:
1011 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001012 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001013 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001014 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001015 index, last_index - index);
1016 page = find_get_page(mapping, index);
1017 if (unlikely(page == NULL))
1018 goto no_cached_page;
1019 }
1020 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001021 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001022 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001023 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001025 if (!PageUptodate(page)) {
1026 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1027 !mapping->a_ops->is_partially_uptodate)
1028 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001029 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001030 goto page_not_up_to_date;
Dave Hansen8d056cb2010-11-11 14:05:15 -08001031 /* Did it get truncated before we got the lock? */
1032 if (!page->mapping)
1033 goto page_not_up_to_date_locked;
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001034 if (!mapping->a_ops->is_partially_uptodate(page,
1035 desc, offset))
1036 goto page_not_up_to_date_locked;
1037 unlock_page(page);
1038 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001040 /*
1041 * i_size must be checked after we know the page is Uptodate.
1042 *
1043 * Checking i_size after the check allows us to calculate
1044 * the correct value for "nr", which means the zero-filled
1045 * part of the page is not copied back to userspace (unless
1046 * another truncate extends the file - this is desired though).
1047 */
1048
1049 isize = i_size_read(inode);
1050 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1051 if (unlikely(!isize || index > end_index)) {
1052 page_cache_release(page);
1053 goto out;
1054 }
1055
1056 /* nr is the maximum number of bytes to copy from this page */
1057 nr = PAGE_CACHE_SIZE;
1058 if (index == end_index) {
1059 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1060 if (nr <= offset) {
1061 page_cache_release(page);
1062 goto out;
1063 }
1064 }
1065 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066
1067 /* If users can be writing to this page using arbitrary
1068 * virtual addresses, take care about potential aliasing
1069 * before reading the page on the kernel side.
1070 */
1071 if (mapping_writably_mapped(mapping))
1072 flush_dcache_page(page);
1073
1074 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001075 * When a sequential read accesses a page several times,
1076 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 */
Jan Karaec0f1632007-05-06 14:49:25 -07001078 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 mark_page_accessed(page);
1080 prev_index = index;
1081
1082 /*
1083 * Ok, we have the page, and it's up-to-date, so
1084 * now we can copy it to user space...
1085 *
1086 * The actor routine returns how many bytes were actually used..
1087 * NOTE! This may not be the same as how much of a user buffer
1088 * we filled up (we may be padding etc), so we can only update
1089 * "pos" here (the actor routine has to update the user buffer
1090 * pointers and the remaining count).
1091 */
1092 ret = actor(desc, page, offset, nr);
1093 offset += ret;
1094 index += offset >> PAGE_CACHE_SHIFT;
1095 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001096 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097
1098 page_cache_release(page);
1099 if (ret == nr && desc->count)
1100 continue;
1101 goto out;
1102
1103page_not_up_to_date:
1104 /* Get exclusive access to the page ... */
Oleg Nesterov85462322008-06-08 21:20:43 +04001105 error = lock_page_killable(page);
1106 if (unlikely(error))
1107 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001109page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001110 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 if (!page->mapping) {
1112 unlock_page(page);
1113 page_cache_release(page);
1114 continue;
1115 }
1116
1117 /* Did somebody else fill it already? */
1118 if (PageUptodate(page)) {
1119 unlock_page(page);
1120 goto page_ok;
1121 }
1122
1123readpage:
Jeff Moyer91803b42010-05-26 11:49:40 -04001124 /*
1125 * A previous I/O error may have been due to temporary
1126 * failures, eg. multipath errors.
1127 * PG_error will be set again if readpage fails.
1128 */
1129 ClearPageError(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001130 /* Start the actual read. The read will unlock the page. */
1131 error = mapping->a_ops->readpage(filp, page);
1132
Zach Brown994fc28c2005-12-15 14:28:17 -08001133 if (unlikely(error)) {
1134 if (error == AOP_TRUNCATED_PAGE) {
1135 page_cache_release(page);
1136 goto find_page;
1137 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001139 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140
1141 if (!PageUptodate(page)) {
Oleg Nesterov85462322008-06-08 21:20:43 +04001142 error = lock_page_killable(page);
1143 if (unlikely(error))
1144 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 if (!PageUptodate(page)) {
1146 if (page->mapping == NULL) {
1147 /*
Christoph Hellwig2ecdc822010-01-26 17:27:20 +01001148 * invalidate_mapping_pages got it
Linus Torvalds1da177e2005-04-16 15:20:36 -07001149 */
1150 unlock_page(page);
1151 page_cache_release(page);
1152 goto find_page;
1153 }
1154 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001155 shrink_readahead_size_eio(filp, ra);
Oleg Nesterov85462322008-06-08 21:20:43 +04001156 error = -EIO;
1157 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 }
1159 unlock_page(page);
1160 }
1161
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162 goto page_ok;
1163
1164readpage_error:
1165 /* UHHUH! A synchronous read error occurred. Report it */
1166 desc->error = error;
1167 page_cache_release(page);
1168 goto out;
1169
1170no_cached_page:
1171 /*
1172 * Ok, it wasn't cached, so we need to create a new
1173 * page..
1174 */
Nick Piggineb2be182007-10-16 01:24:57 -07001175 page = page_cache_alloc_cold(mapping);
1176 if (!page) {
1177 desc->error = -ENOMEM;
1178 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 }
Nick Piggineb2be182007-10-16 01:24:57 -07001180 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 index, GFP_KERNEL);
1182 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001183 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 if (error == -EEXIST)
1185 goto find_page;
1186 desc->error = error;
1187 goto out;
1188 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 goto readpage;
1190 }
1191
1192out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001193 ra->prev_pos = prev_index;
1194 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1195 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001197 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Krishna Kumar0c6aa262008-10-15 22:01:13 -07001198 file_accessed(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200
1201int file_read_actor(read_descriptor_t *desc, struct page *page,
1202 unsigned long offset, unsigned long size)
1203{
1204 char *kaddr;
1205 unsigned long left, count = desc->count;
1206
1207 if (size > count)
1208 size = count;
1209
1210 /*
1211 * Faults on the destination of a read are common, so do it before
1212 * taking the kmap.
1213 */
1214 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1215 kaddr = kmap_atomic(page, KM_USER0);
1216 left = __copy_to_user_inatomic(desc->arg.buf,
1217 kaddr + offset, size);
1218 kunmap_atomic(kaddr, KM_USER0);
1219 if (left == 0)
1220 goto success;
1221 }
1222
1223 /* Do it the slow way */
1224 kaddr = kmap(page);
1225 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1226 kunmap(page);
1227
1228 if (left) {
1229 size -= left;
1230 desc->error = -EFAULT;
1231 }
1232success:
1233 desc->count = count - size;
1234 desc->written += size;
1235 desc->arg.buf += size;
1236 return size;
1237}
1238
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001239/*
1240 * Performs necessary checks before doing a write
1241 * @iov: io vector request
1242 * @nr_segs: number of segments in the iovec
1243 * @count: number of bytes to write
1244 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1245 *
1246 * Adjust number of segments and amount of bytes to write (nr_segs should be
1247 * properly initialized first). Returns appropriate error code that caller
1248 * should return or zero in case that write should be allowed.
1249 */
1250int generic_segment_checks(const struct iovec *iov,
1251 unsigned long *nr_segs, size_t *count, int access_flags)
1252{
1253 unsigned long seg;
1254 size_t cnt = 0;
1255 for (seg = 0; seg < *nr_segs; seg++) {
1256 const struct iovec *iv = &iov[seg];
1257
1258 /*
1259 * If any segment has a negative length, or the cumulative
1260 * length ever wraps negative then return -EINVAL.
1261 */
1262 cnt += iv->iov_len;
1263 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1264 return -EINVAL;
1265 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1266 continue;
1267 if (seg == 0)
1268 return -EFAULT;
1269 *nr_segs = seg;
1270 cnt -= iv->iov_len; /* This segment is no good */
1271 break;
1272 }
1273 *count = cnt;
1274 return 0;
1275}
1276EXPORT_SYMBOL(generic_segment_checks);
1277
Randy Dunlap485bb992006-06-23 02:03:49 -07001278/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001279 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001280 * @iocb: kernel I/O control block
1281 * @iov: io vector request
1282 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001283 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001284 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285 * This is the "read()" routine for all filesystems
1286 * that can use the page cache directly.
1287 */
1288ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001289generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1290 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001291{
1292 struct file *filp = iocb->ki_filp;
1293 ssize_t retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001294 unsigned long seg = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001296 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297
1298 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001299 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1300 if (retval)
1301 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302
1303 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1304 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001305 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001306 struct address_space *mapping;
1307 struct inode *inode;
1308
1309 mapping = filp->f_mapping;
1310 inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311 if (!count)
1312 goto out; /* skip atime */
1313 size = i_size_read(inode);
1314 if (pos < size) {
Nick Piggin48b47c52009-01-06 14:40:22 -08001315 retval = filemap_write_and_wait_range(mapping, pos,
1316 pos + iov_length(iov, nr_segs) - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07001317 if (!retval) {
1318 retval = mapping->a_ops->direct_IO(READ, iocb,
1319 iov, pos, nr_segs);
1320 }
Josef Bacik66f998f2010-05-23 11:00:54 -04001321 if (retval > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 *ppos = pos + retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001323 count -= retval;
1324 }
1325
1326 /*
1327 * Btrfs can have a short DIO read if we encounter
1328 * compressed extents, so if there was an error, or if
1329 * we've already read everything we wanted to, or if
1330 * there was a short read because we hit EOF, go ahead
1331 * and return. Otherwise fallthrough to buffered io for
1332 * the rest of the read.
1333 */
1334 if (retval < 0 || !count || *ppos >= size) {
Hugh Dickins11fa9772008-07-23 21:27:34 -07001335 file_accessed(filp);
1336 goto out;
1337 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001338 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 }
1340
Josef Bacik66f998f2010-05-23 11:00:54 -04001341 count = retval;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001342 for (seg = 0; seg < nr_segs; seg++) {
1343 read_descriptor_t desc;
Josef Bacik66f998f2010-05-23 11:00:54 -04001344 loff_t offset = 0;
1345
1346 /*
1347 * If we did a short DIO read we need to skip the section of the
1348 * iov that we've already read data into.
1349 */
1350 if (count) {
1351 if (count > iov[seg].iov_len) {
1352 count -= iov[seg].iov_len;
1353 continue;
1354 }
1355 offset = count;
1356 count = 0;
1357 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358
Hugh Dickins11fa9772008-07-23 21:27:34 -07001359 desc.written = 0;
Josef Bacik66f998f2010-05-23 11:00:54 -04001360 desc.arg.buf = iov[seg].iov_base + offset;
1361 desc.count = iov[seg].iov_len - offset;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001362 if (desc.count == 0)
1363 continue;
1364 desc.error = 0;
1365 do_generic_file_read(filp, ppos, &desc, file_read_actor);
1366 retval += desc.written;
1367 if (desc.error) {
1368 retval = retval ?: desc.error;
1369 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 }
Hugh Dickins11fa9772008-07-23 21:27:34 -07001371 if (desc.count > 0)
1372 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 }
1374out:
1375 return retval;
1376}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377EXPORT_SYMBOL(generic_file_aio_read);
1378
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379static ssize_t
1380do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001381 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382{
1383 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1384 return -EINVAL;
1385
Wu Fengguangf7e839d2009-06-16 15:31:20 -07001386 force_page_cache_readahead(mapping, filp, index, nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387 return 0;
1388}
1389
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001390SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391{
1392 ssize_t ret;
1393 struct file *file;
1394
1395 ret = -EBADF;
1396 file = fget(fd);
1397 if (file) {
1398 if (file->f_mode & FMODE_READ) {
1399 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001400 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1401 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 unsigned long len = end - start + 1;
1403 ret = do_readahead(mapping, file, start, len);
1404 }
1405 fput(file);
1406 }
1407 return ret;
1408}
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001409#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1410asmlinkage long SyS_readahead(long fd, loff_t offset, long count)
1411{
1412 return SYSC_readahead((int) fd, offset, (size_t) count);
1413}
1414SYSCALL_ALIAS(sys_readahead, SyS_readahead);
1415#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416
1417#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001418/**
1419 * page_cache_read - adds requested page to the page cache if not already there
1420 * @file: file to read
1421 * @offset: page index
1422 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 * This adds the requested page to the page cache if it isn't already there,
1424 * and schedules an I/O to read in its contents from disk.
1425 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001426static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427{
1428 struct address_space *mapping = file->f_mapping;
1429 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001430 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431
Zach Brown994fc28c2005-12-15 14:28:17 -08001432 do {
1433 page = page_cache_alloc_cold(mapping);
1434 if (!page)
1435 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436
Zach Brown994fc28c2005-12-15 14:28:17 -08001437 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1438 if (ret == 0)
1439 ret = mapping->a_ops->readpage(file, page);
1440 else if (ret == -EEXIST)
1441 ret = 0; /* losing race to add is OK */
1442
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001444
Zach Brown994fc28c2005-12-15 14:28:17 -08001445 } while (ret == AOP_TRUNCATED_PAGE);
1446
1447 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448}
1449
1450#define MMAP_LOTSAMISS (100)
1451
Linus Torvaldsef00e082009-06-16 15:31:25 -07001452/*
1453 * Synchronous readahead happens when we don't even find
1454 * a page in the page cache at all.
1455 */
1456static void do_sync_mmap_readahead(struct vm_area_struct *vma,
1457 struct file_ra_state *ra,
1458 struct file *file,
1459 pgoff_t offset)
1460{
1461 unsigned long ra_pages;
1462 struct address_space *mapping = file->f_mapping;
1463
1464 /* If we don't want any read-ahead, don't bother */
1465 if (VM_RandomReadHint(vma))
1466 return;
1467
Wu Fengguang70ac23c2009-06-16 15:31:28 -07001468 if (VM_SequentialReadHint(vma) ||
1469 offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) {
Wu Fengguang7ffc59b2009-06-16 15:31:38 -07001470 page_cache_sync_readahead(mapping, ra, file, offset,
1471 ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001472 return;
1473 }
1474
1475 if (ra->mmap_miss < INT_MAX)
1476 ra->mmap_miss++;
1477
1478 /*
1479 * Do we miss much more than hit in this file? If so,
1480 * stop bothering with read-ahead. It will only hurt.
1481 */
1482 if (ra->mmap_miss > MMAP_LOTSAMISS)
1483 return;
1484
Wu Fengguangd30a1102009-06-16 15:31:30 -07001485 /*
1486 * mmap read-around
1487 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001488 ra_pages = max_sane_readahead(ra->ra_pages);
1489 if (ra_pages) {
Wu Fengguangd30a1102009-06-16 15:31:30 -07001490 ra->start = max_t(long, 0, offset - ra_pages/2);
1491 ra->size = ra_pages;
1492 ra->async_size = 0;
1493 ra_submit(ra, mapping, file);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001494 }
1495}
1496
1497/*
1498 * Asynchronous readahead happens when we find the page and PG_readahead,
1499 * so we want to possibly extend the readahead further..
1500 */
1501static void do_async_mmap_readahead(struct vm_area_struct *vma,
1502 struct file_ra_state *ra,
1503 struct file *file,
1504 struct page *page,
1505 pgoff_t offset)
1506{
1507 struct address_space *mapping = file->f_mapping;
1508
1509 /* If we don't want any read-ahead, don't bother */
1510 if (VM_RandomReadHint(vma))
1511 return;
1512 if (ra->mmap_miss > 0)
1513 ra->mmap_miss--;
1514 if (PageReadahead(page))
Wu Fengguang2fad6f52009-06-16 15:31:29 -07001515 page_cache_async_readahead(mapping, ra, file,
1516 page, offset, ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001517}
1518
Randy Dunlap485bb992006-06-23 02:03:49 -07001519/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001520 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001521 * @vma: vma in which the fault was taken
1522 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001523 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001524 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 * mapped memory region to read in file data during a page fault.
1526 *
1527 * The goto's are kind of ugly, but this streamlines the normal case of having
1528 * it in the page cache, and handles the special cases reasonably without
1529 * having a lot of duplicated code.
1530 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001531int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532{
1533 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001534 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535 struct address_space *mapping = file->f_mapping;
1536 struct file_ra_state *ra = &file->f_ra;
1537 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001538 pgoff_t offset = vmf->pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001540 pgoff_t size;
Nick Piggin83c54072007-07-19 01:47:05 -07001541 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001542
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001544 if (offset >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001545 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 * Do we have something in the page cache already?
1549 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001550 page = find_get_page(mapping, offset);
1551 if (likely(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07001553 * We found the page, so try async readahead before
1554 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001556 do_async_mmap_readahead(vma, ra, file, page, offset);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001557 } else {
1558 /* No page in the page cache at all */
1559 do_sync_mmap_readahead(vma, ra, file, offset);
1560 count_vm_event(PGMAJFAULT);
1561 ret = VM_FAULT_MAJOR;
1562retry_find:
Michel Lespinasseb522c942010-10-26 14:21:56 -07001563 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 if (!page)
1565 goto no_cached_page;
1566 }
1567
Michel Lespinassed88c0922010-11-02 13:05:18 -07001568 if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
1569 page_cache_release(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -07001570 return ret | VM_FAULT_RETRY;
Michel Lespinassed88c0922010-11-02 13:05:18 -07001571 }
Michel Lespinasseb522c942010-10-26 14:21:56 -07001572
1573 /* Did it get truncated? */
1574 if (unlikely(page->mapping != mapping)) {
1575 unlock_page(page);
1576 put_page(page);
1577 goto retry_find;
1578 }
1579 VM_BUG_ON(page->index != offset);
1580
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001582 * We have a locked page in the page cache, now we need to check
1583 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 */
Nick Piggind00806b2007-07-19 01:46:57 -07001585 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586 goto page_not_uptodate;
1587
Linus Torvaldsef00e082009-06-16 15:31:25 -07001588 /*
1589 * Found the page and have a reference on it.
1590 * We must recheck i_size under page lock.
1591 */
Nick Piggind00806b2007-07-19 01:46:57 -07001592 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001593 if (unlikely(offset >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001594 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001595 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001596 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001597 }
1598
Linus Torvaldsef00e082009-06-16 15:31:25 -07001599 ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001600 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001601 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603no_cached_page:
1604 /*
1605 * We're only likely to ever get here if MADV_RANDOM is in
1606 * effect.
1607 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001608 error = page_cache_read(file, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609
1610 /*
1611 * The page we want has now been added to the page cache.
1612 * In the unlikely event that someone removed it in the
1613 * meantime, we'll just come back here and read it again.
1614 */
1615 if (error >= 0)
1616 goto retry_find;
1617
1618 /*
1619 * An error return from page_cache_read can result if the
1620 * system is low on memory, or a problem occurs while trying
1621 * to schedule I/O.
1622 */
1623 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001624 return VM_FAULT_OOM;
1625 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626
1627page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 /*
1629 * Umm, take care of errors if the page isn't up-to-date.
1630 * Try to re-read it _once_. We do this synchronously,
1631 * because there really aren't any performance issues here
1632 * and we need to check for errors.
1633 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001635 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001636 if (!error) {
1637 wait_on_page_locked(page);
1638 if (!PageUptodate(page))
1639 error = -EIO;
1640 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001642
1643 if (!error || error == AOP_TRUNCATED_PAGE)
1644 goto retry_find;
1645
1646 /* Things didn't work out. Return zero to tell the mm layer so. */
1647 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001648 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001649}
1650EXPORT_SYMBOL(filemap_fault);
1651
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04001652const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001653 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654};
1655
1656/* This is used for a general mmap of a disk file */
1657
1658int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1659{
1660 struct address_space *mapping = file->f_mapping;
1661
1662 if (!mapping->a_ops->readpage)
1663 return -ENOEXEC;
1664 file_accessed(file);
1665 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001666 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 return 0;
1668}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669
1670/*
1671 * This is for filesystems which do not implement ->writepage.
1672 */
1673int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1674{
1675 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1676 return -EINVAL;
1677 return generic_file_mmap(file, vma);
1678}
1679#else
1680int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1681{
1682 return -ENOSYS;
1683}
1684int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1685{
1686 return -ENOSYS;
1687}
1688#endif /* CONFIG_MMU */
1689
1690EXPORT_SYMBOL(generic_file_mmap);
1691EXPORT_SYMBOL(generic_file_readonly_mmap);
1692
Nick Piggin6fe69002007-05-06 14:49:04 -07001693static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001694 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001696 void *data,
1697 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698{
Nick Piggineb2be182007-10-16 01:24:57 -07001699 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700 int err;
1701repeat:
1702 page = find_get_page(mapping, index);
1703 if (!page) {
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001704 page = __page_cache_alloc(gfp | __GFP_COLD);
Nick Piggineb2be182007-10-16 01:24:57 -07001705 if (!page)
1706 return ERR_PTR(-ENOMEM);
1707 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1708 if (unlikely(err)) {
1709 page_cache_release(page);
1710 if (err == -EEXIST)
1711 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713 return ERR_PTR(err);
1714 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 err = filler(data, page);
1716 if (err < 0) {
1717 page_cache_release(page);
1718 page = ERR_PTR(err);
1719 }
1720 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721 return page;
1722}
1723
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001724static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001725 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001727 void *data,
1728 gfp_t gfp)
1729
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730{
1731 struct page *page;
1732 int err;
1733
1734retry:
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001735 page = __read_cache_page(mapping, index, filler, data, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001737 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001738 if (PageUptodate(page))
1739 goto out;
1740
1741 lock_page(page);
1742 if (!page->mapping) {
1743 unlock_page(page);
1744 page_cache_release(page);
1745 goto retry;
1746 }
1747 if (PageUptodate(page)) {
1748 unlock_page(page);
1749 goto out;
1750 }
1751 err = filler(data, page);
1752 if (err < 0) {
1753 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001754 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 }
David Howellsc855ff32007-05-09 13:42:20 +01001756out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001757 mark_page_accessed(page);
1758 return page;
1759}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001760
1761/**
1762 * read_cache_page_async - read into page cache, fill it if needed
1763 * @mapping: the page's address_space
1764 * @index: the page index
1765 * @filler: function to perform the read
1766 * @data: destination for read data
1767 *
1768 * Same as read_cache_page, but don't wait for page to become unlocked
1769 * after submitting it to the filler.
1770 *
1771 * Read into the page cache. If a page already exists, and PageUptodate() is
1772 * not set, try to fill the page but don't wait for it to become unlocked.
1773 *
1774 * If the page does not get brought uptodate, return -EIO.
1775 */
1776struct page *read_cache_page_async(struct address_space *mapping,
1777 pgoff_t index,
1778 int (*filler)(void *,struct page*),
1779 void *data)
1780{
1781 return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
1782}
Nick Piggin6fe69002007-05-06 14:49:04 -07001783EXPORT_SYMBOL(read_cache_page_async);
1784
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001785static struct page *wait_on_page_read(struct page *page)
1786{
1787 if (!IS_ERR(page)) {
1788 wait_on_page_locked(page);
1789 if (!PageUptodate(page)) {
1790 page_cache_release(page);
1791 page = ERR_PTR(-EIO);
1792 }
1793 }
1794 return page;
1795}
1796
1797/**
1798 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
1799 * @mapping: the page's address_space
1800 * @index: the page index
1801 * @gfp: the page allocator flags to use if allocating
1802 *
1803 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
1804 * any new page allocations done using the specified allocation flags. Note
1805 * that the Radix tree operations will still use GFP_KERNEL, so you can't
1806 * expect to do this atomically or anything like that - but you can pass in
1807 * other page requirements.
1808 *
1809 * If the page does not get brought uptodate, return -EIO.
1810 */
1811struct page *read_cache_page_gfp(struct address_space *mapping,
1812 pgoff_t index,
1813 gfp_t gfp)
1814{
1815 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
1816
1817 return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp));
1818}
1819EXPORT_SYMBOL(read_cache_page_gfp);
1820
Nick Piggin6fe69002007-05-06 14:49:04 -07001821/**
1822 * read_cache_page - read into page cache, fill it if needed
1823 * @mapping: the page's address_space
1824 * @index: the page index
1825 * @filler: function to perform the read
1826 * @data: destination for read data
1827 *
1828 * Read into the page cache. If a page already exists, and PageUptodate() is
1829 * not set, try to fill the page then wait for it to become unlocked.
1830 *
1831 * If the page does not get brought uptodate, return -EIO.
1832 */
1833struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001834 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001835 int (*filler)(void *,struct page*),
1836 void *data)
1837{
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001838 return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840EXPORT_SYMBOL(read_cache_page);
1841
1842/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 * The logic we want is
1844 *
1845 * if suid or (sgid and xgrp)
1846 * remove privs
1847 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001848int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849{
1850 mode_t mode = dentry->d_inode->i_mode;
1851 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852
1853 /* suid always must be killed */
1854 if (unlikely(mode & S_ISUID))
1855 kill = ATTR_KILL_SUID;
1856
1857 /*
1858 * sgid without any exec bits is just a mandatory locking mark; leave
1859 * it alone. If some exec bits are set, it's a real sgid; kill it.
1860 */
1861 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1862 kill |= ATTR_KILL_SGID;
1863
Dmitri Monakhov7f5ff762008-12-01 14:34:56 -08001864 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
Jens Axboe01de85e2006-10-17 19:50:36 +02001865 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866
Jens Axboe01de85e2006-10-17 19:50:36 +02001867 return 0;
1868}
Mark Fashehd23a1472006-10-17 17:05:18 -07001869EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001870
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +02001871static int __remove_suid(struct dentry *dentry, int kill)
Jens Axboe01de85e2006-10-17 19:50:36 +02001872{
1873 struct iattr newattrs;
1874
1875 newattrs.ia_valid = ATTR_FORCE | kill;
1876 return notify_change(dentry, &newattrs);
1877}
1878
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001879int file_remove_suid(struct file *file)
Jens Axboe01de85e2006-10-17 19:50:36 +02001880{
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001881 struct dentry *dentry = file->f_path.dentry;
Serge E. Hallynb5376772007-10-16 23:31:36 -07001882 int killsuid = should_remove_suid(dentry);
1883 int killpriv = security_inode_need_killpriv(dentry);
1884 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001885
Serge E. Hallynb5376772007-10-16 23:31:36 -07001886 if (killpriv < 0)
1887 return killpriv;
1888 if (killpriv)
1889 error = security_inode_killpriv(dentry);
1890 if (!error && killsuid)
1891 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001892
Serge E. Hallynb5376772007-10-16 23:31:36 -07001893 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894}
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001895EXPORT_SYMBOL(file_remove_suid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896
Nick Piggin2f718ff2007-10-16 01:24:59 -07001897static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898 const struct iovec *iov, size_t base, size_t bytes)
1899{
Ingo Molnarf1800532009-03-02 11:00:57 +01001900 size_t copied = 0, left = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901
1902 while (bytes) {
1903 char __user *buf = iov->iov_base + base;
1904 int copy = min(bytes, iov->iov_len - base);
1905
1906 base = 0;
Ingo Molnarf1800532009-03-02 11:00:57 +01001907 left = __copy_from_user_inatomic(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001908 copied += copy;
1909 bytes -= copy;
1910 vaddr += copy;
1911 iov++;
1912
NeilBrown01408c42006-06-25 05:47:58 -07001913 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001915 }
1916 return copied - left;
1917}
1918
1919/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001920 * Copy as much as we can into the page and return the number of bytes which
André Goddard Rosaaf901ca2009-11-14 13:09:05 -02001921 * were successfully copied. If a fault is encountered then return the number of
Nick Piggin2f718ff2007-10-16 01:24:59 -07001922 * bytes which were copied.
1923 */
1924size_t iov_iter_copy_from_user_atomic(struct page *page,
1925 struct iov_iter *i, unsigned long offset, size_t bytes)
1926{
1927 char *kaddr;
1928 size_t copied;
1929
1930 BUG_ON(!in_atomic());
1931 kaddr = kmap_atomic(page, KM_USER0);
1932 if (likely(i->nr_segs == 1)) {
1933 int left;
1934 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001935 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001936 copied = bytes - left;
1937 } else {
1938 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1939 i->iov, i->iov_offset, bytes);
1940 }
1941 kunmap_atomic(kaddr, KM_USER0);
1942
1943 return copied;
1944}
Nick Piggin89e10782007-10-16 01:25:07 -07001945EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001946
1947/*
1948 * This has the same sideeffects and return value as
1949 * iov_iter_copy_from_user_atomic().
1950 * The difference is that it attempts to resolve faults.
1951 * Page must not be locked.
1952 */
1953size_t iov_iter_copy_from_user(struct page *page,
1954 struct iov_iter *i, unsigned long offset, size_t bytes)
1955{
1956 char *kaddr;
1957 size_t copied;
1958
1959 kaddr = kmap(page);
1960 if (likely(i->nr_segs == 1)) {
1961 int left;
1962 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001963 left = __copy_from_user(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001964 copied = bytes - left;
1965 } else {
1966 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
1967 i->iov, i->iov_offset, bytes);
1968 }
1969 kunmap(page);
1970 return copied;
1971}
Nick Piggin89e10782007-10-16 01:25:07 -07001972EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07001973
Nick Pigginf7009262008-03-10 11:43:59 -07001974void iov_iter_advance(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07001975{
Nick Pigginf7009262008-03-10 11:43:59 -07001976 BUG_ON(i->count < bytes);
1977
Nick Piggin2f718ff2007-10-16 01:24:59 -07001978 if (likely(i->nr_segs == 1)) {
1979 i->iov_offset += bytes;
Nick Pigginf7009262008-03-10 11:43:59 -07001980 i->count -= bytes;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001981 } else {
1982 const struct iovec *iov = i->iov;
1983 size_t base = i->iov_offset;
1984
Nick Piggin124d3b72008-02-02 15:01:17 +01001985 /*
1986 * The !iov->iov_len check ensures we skip over unlikely
Nick Pigginf7009262008-03-10 11:43:59 -07001987 * zero-length segments (without overruning the iovec).
Nick Piggin124d3b72008-02-02 15:01:17 +01001988 */
Linus Torvalds94ad3742008-07-30 14:45:12 -07001989 while (bytes || unlikely(i->count && !iov->iov_len)) {
Nick Pigginf7009262008-03-10 11:43:59 -07001990 int copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001991
Nick Pigginf7009262008-03-10 11:43:59 -07001992 copy = min(bytes, iov->iov_len - base);
1993 BUG_ON(!i->count || i->count < copy);
1994 i->count -= copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07001995 bytes -= copy;
1996 base += copy;
1997 if (iov->iov_len == base) {
1998 iov++;
1999 base = 0;
2000 }
2001 }
2002 i->iov = iov;
2003 i->iov_offset = base;
2004 }
2005}
Nick Piggin89e10782007-10-16 01:25:07 -07002006EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002007
Nick Pigginafddba42007-10-16 01:25:01 -07002008/*
2009 * Fault in the first iovec of the given iov_iter, to a maximum length
2010 * of bytes. Returns 0 on success, or non-zero if the memory could not be
2011 * accessed (ie. because it is an invalid address).
2012 *
2013 * writev-intensive code may want this to prefault several iovecs -- that
2014 * would be possible (callers must not rely on the fact that _only_ the
2015 * first iovec will be faulted with the current implementation).
2016 */
2017int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07002018{
Nick Piggin2f718ff2007-10-16 01:24:59 -07002019 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07002020 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
2021 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002022}
Nick Piggin89e10782007-10-16 01:25:07 -07002023EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002024
2025/*
2026 * Return the count of just the current iov_iter segment.
2027 */
2028size_t iov_iter_single_seg_count(struct iov_iter *i)
2029{
2030 const struct iovec *iov = i->iov;
2031 if (i->nr_segs == 1)
2032 return i->count;
2033 else
2034 return min(i->count, iov->iov_len - i->iov_offset);
2035}
Nick Piggin89e10782007-10-16 01:25:07 -07002036EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002037
2038/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002039 * Performs necessary checks before doing a write
2040 *
Randy Dunlap485bb992006-06-23 02:03:49 -07002041 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002042 * Returns appropriate error code that caller should return or
2043 * zero in case that write should be allowed.
2044 */
2045inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
2046{
2047 struct inode *inode = file->f_mapping->host;
Jiri Slaby59e99e52010-03-05 13:41:44 -08002048 unsigned long limit = rlimit(RLIMIT_FSIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049
2050 if (unlikely(*pos < 0))
2051 return -EINVAL;
2052
Linus Torvalds1da177e2005-04-16 15:20:36 -07002053 if (!isblk) {
2054 /* FIXME: this is for backwards compatibility with 2.4 */
2055 if (file->f_flags & O_APPEND)
2056 *pos = i_size_read(inode);
2057
2058 if (limit != RLIM_INFINITY) {
2059 if (*pos >= limit) {
2060 send_sig(SIGXFSZ, current, 0);
2061 return -EFBIG;
2062 }
2063 if (*count > limit - (typeof(limit))*pos) {
2064 *count = limit - (typeof(limit))*pos;
2065 }
2066 }
2067 }
2068
2069 /*
2070 * LFS rule
2071 */
2072 if (unlikely(*pos + *count > MAX_NON_LFS &&
2073 !(file->f_flags & O_LARGEFILE))) {
2074 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075 return -EFBIG;
2076 }
2077 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2078 *count = MAX_NON_LFS - (unsigned long)*pos;
2079 }
2080 }
2081
2082 /*
2083 * Are we about to exceed the fs block limit ?
2084 *
2085 * If we have written data it becomes a short write. If we have
2086 * exceeded without writing data we send a signal and return EFBIG.
2087 * Linus frestrict idea will clean these up nicely..
2088 */
2089 if (likely(!isblk)) {
2090 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2091 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 return -EFBIG;
2093 }
2094 /* zero-length writes at ->s_maxbytes are OK */
2095 }
2096
2097 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2098 *count = inode->i_sb->s_maxbytes - *pos;
2099 } else {
David Howells93614012006-09-30 20:45:40 +02002100#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002101 loff_t isize;
2102 if (bdev_read_only(I_BDEV(inode)))
2103 return -EPERM;
2104 isize = i_size_read(inode);
2105 if (*pos >= isize) {
2106 if (*count || *pos > isize)
2107 return -ENOSPC;
2108 }
2109
2110 if (*pos + *count > isize)
2111 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002112#else
2113 return -EPERM;
2114#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115 }
2116 return 0;
2117}
2118EXPORT_SYMBOL(generic_write_checks);
2119
Nick Pigginafddba42007-10-16 01:25:01 -07002120int pagecache_write_begin(struct file *file, struct address_space *mapping,
2121 loff_t pos, unsigned len, unsigned flags,
2122 struct page **pagep, void **fsdata)
2123{
2124 const struct address_space_operations *aops = mapping->a_ops;
2125
Nick Piggin4e02ed42008-10-29 14:00:55 -07002126 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002127 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002128}
2129EXPORT_SYMBOL(pagecache_write_begin);
2130
2131int pagecache_write_end(struct file *file, struct address_space *mapping,
2132 loff_t pos, unsigned len, unsigned copied,
2133 struct page *page, void *fsdata)
2134{
2135 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002136
Nick Piggin4e02ed42008-10-29 14:00:55 -07002137 mark_page_accessed(page);
2138 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002139}
2140EXPORT_SYMBOL(pagecache_write_end);
2141
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142ssize_t
2143generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2144 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2145 size_t count, size_t ocount)
2146{
2147 struct file *file = iocb->ki_filp;
2148 struct address_space *mapping = file->f_mapping;
2149 struct inode *inode = mapping->host;
2150 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002151 size_t write_len;
2152 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153
2154 if (count != ocount)
2155 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2156
Christoph Hellwiga969e902008-07-23 21:27:04 -07002157 write_len = iov_length(iov, *nr_segs);
2158 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002159
Nick Piggin48b47c52009-01-06 14:40:22 -08002160 written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002161 if (written)
2162 goto out;
2163
2164 /*
2165 * After a write we want buffered reads to be sure to go to disk to get
2166 * the new data. We invalidate clean cached page from the region we're
2167 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002168 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002169 */
2170 if (mapping->nrpages) {
2171 written = invalidate_inode_pages2_range(mapping,
2172 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002173 /*
2174 * If a page can not be invalidated, return 0 to fall back
2175 * to buffered write.
2176 */
2177 if (written) {
2178 if (written == -EBUSY)
2179 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002180 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002181 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002182 }
2183
2184 written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2185
2186 /*
2187 * Finally, try again to invalidate clean pages which might have been
2188 * cached by non-direct readahead, or faulted in by get_user_pages()
2189 * if the source of the write was an mmap'ed region of the file
2190 * we're writing. Either one is a pretty crazy thing to do,
2191 * so we don't support it 100%. If this invalidation
2192 * fails, tough, the write still worked...
2193 */
2194 if (mapping->nrpages) {
2195 invalidate_inode_pages2_range(mapping,
2196 pos >> PAGE_CACHE_SHIFT, end);
2197 }
2198
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 if (written > 0) {
Namhyung Kim01166512010-10-26 14:21:58 -07002200 pos += written;
2201 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2202 i_size_write(inode, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002203 mark_inode_dirty(inode);
2204 }
Namhyung Kim01166512010-10-26 14:21:58 -07002205 *ppos = pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002207out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002208 return written;
2209}
2210EXPORT_SYMBOL(generic_file_direct_write);
2211
Nick Piggineb2be182007-10-16 01:24:57 -07002212/*
2213 * Find or create a page at the given pagecache position. Return the locked
2214 * page. This function is specifically for buffered writes.
2215 */
Nick Piggin54566b22009-01-04 12:00:53 -08002216struct page *grab_cache_page_write_begin(struct address_space *mapping,
2217 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07002218{
2219 int status;
2220 struct page *page;
Nick Piggin54566b22009-01-04 12:00:53 -08002221 gfp_t gfp_notmask = 0;
2222 if (flags & AOP_FLAG_NOFS)
2223 gfp_notmask = __GFP_FS;
Nick Piggineb2be182007-10-16 01:24:57 -07002224repeat:
2225 page = find_lock_page(mapping, index);
2226 if (likely(page))
2227 return page;
2228
Nick Piggin54566b22009-01-04 12:00:53 -08002229 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002230 if (!page)
2231 return NULL;
Nick Piggin54566b22009-01-04 12:00:53 -08002232 status = add_to_page_cache_lru(page, mapping, index,
2233 GFP_KERNEL & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002234 if (unlikely(status)) {
2235 page_cache_release(page);
2236 if (status == -EEXIST)
2237 goto repeat;
2238 return NULL;
2239 }
2240 return page;
2241}
Nick Piggin54566b22009-01-04 12:00:53 -08002242EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07002243
Nick Pigginafddba42007-10-16 01:25:01 -07002244static ssize_t generic_perform_write(struct file *file,
2245 struct iov_iter *i, loff_t pos)
2246{
2247 struct address_space *mapping = file->f_mapping;
2248 const struct address_space_operations *a_ops = mapping->a_ops;
2249 long status = 0;
2250 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002251 unsigned int flags = 0;
2252
2253 /*
2254 * Copies from kernel address space cannot fail (NFSD is a big user).
2255 */
2256 if (segment_eq(get_fs(), KERNEL_DS))
2257 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002258
2259 do {
2260 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07002261 unsigned long offset; /* Offset into pagecache page */
2262 unsigned long bytes; /* Bytes to write to page */
2263 size_t copied; /* Bytes copied from user */
2264 void *fsdata;
2265
2266 offset = (pos & (PAGE_CACHE_SIZE - 1));
Nick Pigginafddba42007-10-16 01:25:01 -07002267 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2268 iov_iter_count(i));
2269
2270again:
2271
2272 /*
2273 * Bring in the user page that we will copy from _first_.
2274 * Otherwise there's a nasty deadlock on copying from the
2275 * same page as we're writing to, without it being marked
2276 * up-to-date.
2277 *
2278 * Not only is this an optimisation, but it is also required
2279 * to check that the address is actually valid, when atomic
2280 * usercopies are used, below.
2281 */
2282 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2283 status = -EFAULT;
2284 break;
2285 }
2286
Nick Piggin674b8922007-10-16 01:25:03 -07002287 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002288 &page, &fsdata);
2289 if (unlikely(status))
2290 break;
2291
anfei zhou931e80e2010-02-02 13:44:02 -08002292 if (mapping_writably_mapped(mapping))
2293 flush_dcache_page(page);
2294
Nick Pigginafddba42007-10-16 01:25:01 -07002295 pagefault_disable();
2296 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2297 pagefault_enable();
2298 flush_dcache_page(page);
2299
Josef Bacikc8236db2009-07-05 12:08:18 -07002300 mark_page_accessed(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002301 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2302 page, fsdata);
2303 if (unlikely(status < 0))
2304 break;
2305 copied = status;
2306
2307 cond_resched();
2308
Nick Piggin124d3b72008-02-02 15:01:17 +01002309 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002310 if (unlikely(copied == 0)) {
2311 /*
2312 * If we were unable to copy any data at all, we must
2313 * fall back to a single segment length write.
2314 *
2315 * If we didn't fallback here, we could livelock
2316 * because not all segments in the iov can be copied at
2317 * once without a pagefault.
2318 */
2319 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2320 iov_iter_single_seg_count(i));
2321 goto again;
2322 }
Nick Pigginafddba42007-10-16 01:25:01 -07002323 pos += copied;
2324 written += copied;
2325
2326 balance_dirty_pages_ratelimited(mapping);
2327
2328 } while (iov_iter_count(i));
2329
2330 return written ? written : status;
2331}
2332
2333ssize_t
2334generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2335 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2336 size_t count, ssize_t written)
2337{
2338 struct file *file = iocb->ki_filp;
Nick Pigginafddba42007-10-16 01:25:01 -07002339 ssize_t status;
2340 struct iov_iter i;
2341
2342 iov_iter_init(&i, iov, nr_segs, count, written);
Nick Piggin4e02ed42008-10-29 14:00:55 -07002343 status = generic_perform_write(file, &i, pos);
Nick Pigginafddba42007-10-16 01:25:01 -07002344
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002346 written += status;
2347 *ppos = pos + status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 }
2349
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350 return written ? written : status;
2351}
2352EXPORT_SYMBOL(generic_file_buffered_write);
2353
Jan Karae4dd9de2009-08-17 18:10:06 +02002354/**
2355 * __generic_file_aio_write - write data to a file
2356 * @iocb: IO state structure (file, offset, etc.)
2357 * @iov: vector with data to write
2358 * @nr_segs: number of segments in the vector
2359 * @ppos: position where to write
2360 *
2361 * This function does all the work needed for actually writing data to a
2362 * file. It does all basic checks, removes SUID from the file, updates
2363 * modification times and calls proper subroutines depending on whether we
2364 * do direct IO or a standard buffered write.
2365 *
2366 * It expects i_mutex to be grabbed unless we work on a block device or similar
2367 * object which does not need locking at all.
2368 *
2369 * This function does *not* take care of syncing data in case of O_SYNC write.
2370 * A caller has to handle it. This is mainly due to the fact that we want to
2371 * avoid syncing under i_mutex.
2372 */
2373ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2374 unsigned long nr_segs, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002375{
2376 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002377 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002378 size_t ocount; /* original count */
2379 size_t count; /* after file limit checks */
2380 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002381 loff_t pos;
2382 ssize_t written;
2383 ssize_t err;
2384
2385 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002386 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2387 if (err)
2388 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002389
2390 count = ocount;
2391 pos = *ppos;
2392
2393 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2394
2395 /* We can write back this queue in page reclaim */
2396 current->backing_dev_info = mapping->backing_dev_info;
2397 written = 0;
2398
2399 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2400 if (err)
2401 goto out;
2402
2403 if (count == 0)
2404 goto out;
2405
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002406 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002407 if (err)
2408 goto out;
2409
Christoph Hellwig870f4812006-01-09 20:52:01 -08002410 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411
2412 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2413 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002414 loff_t endbyte;
2415 ssize_t written_buffered;
2416
2417 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2418 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002419 if (written < 0 || written == count)
2420 goto out;
2421 /*
2422 * direct-io write to a hole: fall through to buffered I/O
2423 * for completing the rest of the request.
2424 */
2425 pos += written;
2426 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002427 written_buffered = generic_file_buffered_write(iocb, iov,
2428 nr_segs, pos, ppos, count,
2429 written);
2430 /*
2431 * If generic_file_buffered_write() retuned a synchronous error
2432 * then we want to return the number of bytes which were
2433 * direct-written, or the error code if that was zero. Note
2434 * that this differs from normal direct-io semantics, which
2435 * will return -EFOO even if some bytes were written.
2436 */
2437 if (written_buffered < 0) {
2438 err = written_buffered;
2439 goto out;
2440 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002441
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002442 /*
2443 * We need to ensure that the page cache pages are written to
2444 * disk and invalidated to preserve the expected O_DIRECT
2445 * semantics.
2446 */
2447 endbyte = pos + written_buffered - written - 1;
Christoph Hellwigc05c4ed2009-09-23 15:07:30 +02002448 err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002449 if (err == 0) {
2450 written = written_buffered;
2451 invalidate_mapping_pages(mapping,
2452 pos >> PAGE_CACHE_SHIFT,
2453 endbyte >> PAGE_CACHE_SHIFT);
2454 } else {
2455 /*
2456 * We don't know how much we wrote, so just return
2457 * the number of bytes which were direct-written
2458 */
2459 }
2460 } else {
2461 written = generic_file_buffered_write(iocb, iov, nr_segs,
2462 pos, ppos, count, written);
2463 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002464out:
2465 current->backing_dev_info = NULL;
2466 return written ? written : err;
2467}
Jan Karae4dd9de2009-08-17 18:10:06 +02002468EXPORT_SYMBOL(__generic_file_aio_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469
Jan Karae4dd9de2009-08-17 18:10:06 +02002470/**
2471 * generic_file_aio_write - write data to a file
2472 * @iocb: IO state structure
2473 * @iov: vector with data to write
2474 * @nr_segs: number of segments in the vector
2475 * @pos: position in file where to write
2476 *
2477 * This is a wrapper around __generic_file_aio_write() to be used by most
2478 * filesystems. It takes care of syncing the file in case of O_SYNC file
2479 * and acquires i_mutex as needed.
2480 */
Badari Pulavarty027445c2006-09-30 23:28:46 -07002481ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2482 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483{
2484 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02002485 struct inode *inode = file->f_mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002486 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487
2488 BUG_ON(iocb->ki_pos != pos);
2489
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002490 mutex_lock(&inode->i_mutex);
Jan Karae4dd9de2009-08-17 18:10:06 +02002491 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002492 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002493
Jan Kara148f9482009-08-17 19:52:36 +02002494 if (ret > 0 || ret == -EIOCBQUEUED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002495 ssize_t err;
2496
Jan Kara148f9482009-08-17 19:52:36 +02002497 err = generic_write_sync(file, pos, ret);
Jan Karac7b50db2009-08-18 16:18:20 +02002498 if (err < 0 && ret > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002499 ret = err;
2500 }
2501 return ret;
2502}
2503EXPORT_SYMBOL(generic_file_aio_write);
2504
David Howellscf9a2ae2006-08-29 19:05:54 +01002505/**
2506 * try_to_release_page() - release old fs-specific metadata on a page
2507 *
2508 * @page: the page which the kernel is trying to free
2509 * @gfp_mask: memory allocation flags (and I/O mode)
2510 *
2511 * The address_space is to try to release any data against the page
2512 * (presumably at page->private). If the release was successful, return `1'.
2513 * Otherwise return zero.
2514 *
David Howells266cf652009-04-03 16:42:36 +01002515 * This may also be called if PG_fscache is set on a page, indicating that the
2516 * page is known to the local caching routines.
2517 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002518 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fdd2008-07-25 01:46:22 -07002519 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002520 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002521 */
2522int try_to_release_page(struct page *page, gfp_t gfp_mask)
2523{
2524 struct address_space * const mapping = page->mapping;
2525
2526 BUG_ON(!PageLocked(page));
2527 if (PageWriteback(page))
2528 return 0;
2529
2530 if (mapping && mapping->a_ops->releasepage)
2531 return mapping->a_ops->releasepage(page, gfp_mask);
2532 return try_to_free_buffers(page);
2533}
2534
2535EXPORT_SYMBOL(try_to_release_page);