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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 *
Dave Chinnera66979a2011-03-22 22:23:41 +110083 * inode_wb_list_lock
84 * sb_lock (fs/fs-writeback.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 * ->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)
Dave Chinnera66979a2011-03-22 22:23:41 +1100101 * inode_wb_list_lock (page_remove_rmap->set_page_dirty)
Dave Chinner250df6e2011-03-22 22:23:36 +1100102 * ->inode->i_lock (page_remove_rmap->set_page_dirty)
Dave Chinnera66979a2011-03-22 22:23:41 +1100103 * inode_wb_list_lock (zap_pte_range->set_page_dirty)
Dave Chinner250df6e2011-03-22 22:23:36 +1100104 * ->inode->i_lock (zap_pte_range->set_page_dirty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
106 *
Andi Kleen6a460792009-09-16 11:50:15 +0200107 * (code doesn't rely on that order, so you could switch it around)
108 * ->tasklist_lock (memory_failure, collect_procs_ao)
109 * ->i_mmap_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 */
111
112/*
Minchan Kime64a7822011-03-22 16:32:44 -0700113 * Delete a page from the page cache and free it. Caller has to make
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700115 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 */
Minchan Kime64a7822011-03-22 16:32:44 -0700117void __delete_from_page_cache(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118{
119 struct address_space *mapping = page->mapping;
120
121 radix_tree_delete(&mapping->page_tree, page->index);
122 page->mapping = NULL;
123 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700124 __dec_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700125 if (PageSwapBacked(page))
126 __dec_zone_page_state(page, NR_SHMEM);
Nick Piggin45426812007-07-15 23:38:12 -0700127 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800128
129 /*
130 * Some filesystems seem to re-dirty the page even after
131 * the VM has canceled the dirty bit (eg ext3 journaling).
132 *
133 * Fix it up by doing a final dirty accounting check after
134 * having removed the page entirely.
135 */
136 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
137 dec_zone_page_state(page, NR_FILE_DIRTY);
138 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
139 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140}
141
Minchan Kim702cfbf2011-03-22 16:32:43 -0700142/**
143 * delete_from_page_cache - delete page from page cache
144 * @page: the page which the kernel is trying to remove from page cache
145 *
146 * This must be called only on pages that have been verified to be in the page
147 * cache and locked. It will never put the page into the free list, the caller
148 * has a reference on the page.
149 */
150void delete_from_page_cache(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151{
152 struct address_space *mapping = page->mapping;
Linus Torvalds6072d132010-12-01 13:35:19 -0500153 void (*freepage)(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154
Matt Mackallcd7619d2005-05-01 08:59:01 -0700155 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
Linus Torvalds6072d132010-12-01 13:35:19 -0500157 freepage = mapping->a_ops->freepage;
Nick Piggin19fd6232008-07-25 19:45:32 -0700158 spin_lock_irq(&mapping->tree_lock);
Minchan Kime64a7822011-03-22 16:32:44 -0700159 __delete_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700160 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700161 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500162
163 if (freepage)
164 freepage(page);
Minchan Kim97cecb52011-03-22 16:30:53 -0700165 page_cache_release(page);
166}
167EXPORT_SYMBOL(delete_from_page_cache);
168
Jens Axboe7eaceac2011-03-10 08:52:07 +0100169static int sleep_on_page(void *word)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 io_schedule();
172 return 0;
173}
174
Jens Axboe7eaceac2011-03-10 08:52:07 +0100175static int sleep_on_page_killable(void *word)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500176{
Jens Axboe7eaceac2011-03-10 08:52:07 +0100177 sleep_on_page(word);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500178 return fatal_signal_pending(current) ? -EINTR : 0;
179}
180
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700182 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700183 * @mapping: address space structure to write
184 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800185 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700186 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700188 * Start writeback against all of a mapping's dirty pages that lie
189 * within the byte offsets <start, end> inclusive.
190 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700192 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 * these two operations is that if a dirty page/buffer is encountered, it must
194 * be waited upon, and not just skipped over.
195 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800196int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
197 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198{
199 int ret;
200 struct writeback_control wbc = {
201 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800202 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700203 .range_start = start,
204 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 };
206
207 if (!mapping_cap_writeback_dirty(mapping))
208 return 0;
209
210 ret = do_writepages(mapping, &wbc);
211 return ret;
212}
213
214static inline int __filemap_fdatawrite(struct address_space *mapping,
215 int sync_mode)
216{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700217 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218}
219
220int filemap_fdatawrite(struct address_space *mapping)
221{
222 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
223}
224EXPORT_SYMBOL(filemap_fdatawrite);
225
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400226int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800227 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228{
229 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
230}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400231EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
Randy Dunlap485bb992006-06-23 02:03:49 -0700233/**
234 * filemap_flush - mostly a non-blocking flush
235 * @mapping: target address_space
236 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 * This is a mostly non-blocking flush. Not suitable for data-integrity
238 * purposes - I/O may not be started against all dirty pages.
239 */
240int filemap_flush(struct address_space *mapping)
241{
242 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
243}
244EXPORT_SYMBOL(filemap_flush);
245
Randy Dunlap485bb992006-06-23 02:03:49 -0700246/**
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200247 * filemap_fdatawait_range - wait for writeback to complete
248 * @mapping: address space structure to wait for
249 * @start_byte: offset in bytes where the range starts
250 * @end_byte: offset in bytes where the range ends (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -0700251 *
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200252 * Walk the list of under-writeback pages of the given address space
253 * in the given range and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 */
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200255int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
256 loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257{
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200258 pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
259 pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 struct pagevec pvec;
261 int nr_pages;
262 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200264 if (end_byte < start_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 return 0;
266
267 pagevec_init(&pvec, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 while ((index <= end) &&
269 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
270 PAGECACHE_TAG_WRITEBACK,
271 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
272 unsigned i;
273
274 for (i = 0; i < nr_pages; i++) {
275 struct page *page = pvec.pages[i];
276
277 /* until radix tree lookup accepts end_index */
278 if (page->index > end)
279 continue;
280
281 wait_on_page_writeback(page);
Rik van Riel212260a2011-01-13 15:46:06 -0800282 if (TestClearPageError(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 ret = -EIO;
284 }
285 pagevec_release(&pvec);
286 cond_resched();
287 }
288
289 /* Check for outstanding write errors */
290 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
291 ret = -ENOSPC;
292 if (test_and_clear_bit(AS_EIO, &mapping->flags))
293 ret = -EIO;
294
295 return ret;
296}
Jan Karad3bccb6f2009-08-17 19:30:27 +0200297EXPORT_SYMBOL(filemap_fdatawait_range);
298
299/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700300 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700302 *
303 * Walk the list of under-writeback pages of the given address space
304 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 */
306int filemap_fdatawait(struct address_space *mapping)
307{
308 loff_t i_size = i_size_read(mapping->host);
309
310 if (i_size == 0)
311 return 0;
312
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200313 return filemap_fdatawait_range(mapping, 0, i_size - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314}
315EXPORT_SYMBOL(filemap_fdatawait);
316
317int filemap_write_and_wait(struct address_space *mapping)
318{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800319 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
321 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800322 err = filemap_fdatawrite(mapping);
323 /*
324 * Even if the above returned error, the pages may be
325 * written partially (e.g. -ENOSPC), so we wait for it.
326 * But the -EIO is special case, it may indicate the worst
327 * thing (e.g. bug) happened, so we avoid waiting for it.
328 */
329 if (err != -EIO) {
330 int err2 = filemap_fdatawait(mapping);
331 if (!err)
332 err = err2;
333 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800335 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800337EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338
Randy Dunlap485bb992006-06-23 02:03:49 -0700339/**
340 * filemap_write_and_wait_range - write out & wait on a file range
341 * @mapping: the address_space for the pages
342 * @lstart: offset in bytes where the range starts
343 * @lend: offset in bytes where the range ends (inclusive)
344 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800345 * Write out and wait upon file offsets lstart->lend, inclusive.
346 *
347 * Note that `lend' is inclusive (describes the last byte to be written) so
348 * that this function can be used to write to the very end-of-file (end = -1).
349 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350int filemap_write_and_wait_range(struct address_space *mapping,
351 loff_t lstart, loff_t lend)
352{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800353 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
355 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800356 err = __filemap_fdatawrite_range(mapping, lstart, lend,
357 WB_SYNC_ALL);
358 /* See comment of filemap_write_and_wait() */
359 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200360 int err2 = filemap_fdatawait_range(mapping,
361 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800362 if (!err)
363 err = err2;
364 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800366 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367}
Chris Masonf6995582009-04-15 13:22:37 -0400368EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369
Randy Dunlap485bb992006-06-23 02:03:49 -0700370/**
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700371 * replace_page_cache_page - replace a pagecache page with a new one
372 * @old: page to be replaced
373 * @new: page to replace with
374 * @gfp_mask: allocation mode
375 *
376 * This function replaces a page in the pagecache with a new one. On
377 * success it acquires the pagecache reference for the new page and
378 * drops it for the old page. Both the old and new pages must be
379 * locked. This function does not add the new page to the LRU, the
380 * caller must do that.
381 *
382 * The remove + add is atomic. The only way this function can fail is
383 * memory allocation failure.
384 */
385int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
386{
387 int error;
388 struct mem_cgroup *memcg = NULL;
389
390 VM_BUG_ON(!PageLocked(old));
391 VM_BUG_ON(!PageLocked(new));
392 VM_BUG_ON(new->mapping);
393
394 /*
395 * This is not page migration, but prepare_migration and
396 * end_migration does enough work for charge replacement.
397 *
398 * In the longer term we probably want a specialized function
399 * for moving the charge from old to new in a more efficient
400 * manner.
401 */
402 error = mem_cgroup_prepare_migration(old, new, &memcg, gfp_mask);
403 if (error)
404 return error;
405
406 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
407 if (!error) {
408 struct address_space *mapping = old->mapping;
409 void (*freepage)(struct page *);
410
411 pgoff_t offset = old->index;
412 freepage = mapping->a_ops->freepage;
413
414 page_cache_get(new);
415 new->mapping = mapping;
416 new->index = offset;
417
418 spin_lock_irq(&mapping->tree_lock);
Minchan Kime64a7822011-03-22 16:32:44 -0700419 __delete_from_page_cache(old);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700420 error = radix_tree_insert(&mapping->page_tree, offset, new);
421 BUG_ON(error);
422 mapping->nrpages++;
423 __inc_zone_page_state(new, NR_FILE_PAGES);
424 if (PageSwapBacked(new))
425 __inc_zone_page_state(new, NR_SHMEM);
426 spin_unlock_irq(&mapping->tree_lock);
427 radix_tree_preload_end();
428 if (freepage)
429 freepage(old);
430 page_cache_release(old);
431 mem_cgroup_end_migration(memcg, old, new, true);
432 } else {
433 mem_cgroup_end_migration(memcg, old, new, false);
434 }
435
436 return error;
437}
438EXPORT_SYMBOL_GPL(replace_page_cache_page);
439
440/**
Nick Piggine2867812008-07-25 19:45:30 -0700441 * add_to_page_cache_locked - add a locked page to the pagecache
Randy Dunlap485bb992006-06-23 02:03:49 -0700442 * @page: page to add
443 * @mapping: the page's address_space
444 * @offset: page index
445 * @gfp_mask: page allocation mode
446 *
Nick Piggine2867812008-07-25 19:45:30 -0700447 * This function is used to add a page to the pagecache. It must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 * This function does not add the page to the LRU. The caller must do that.
449 */
Nick Piggine2867812008-07-25 19:45:30 -0700450int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400451 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452{
Nick Piggine2867812008-07-25 19:45:30 -0700453 int error;
454
455 VM_BUG_ON(!PageLocked(page));
456
457 error = mem_cgroup_cache_charge(page, current->mm,
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -0800458 gfp_mask & GFP_RECLAIM_MASK);
Balbir Singh35c754d2008-02-07 00:14:05 -0800459 if (error)
460 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461
Balbir Singh35c754d2008-02-07 00:14:05 -0800462 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 if (error == 0) {
Nick Piggine2867812008-07-25 19:45:30 -0700464 page_cache_get(page);
465 page->mapping = mapping;
466 page->index = offset;
467
Nick Piggin19fd6232008-07-25 19:45:32 -0700468 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 error = radix_tree_insert(&mapping->page_tree, offset, page);
Nick Piggine2867812008-07-25 19:45:30 -0700470 if (likely(!error)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700472 __inc_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700473 if (PageSwapBacked(page))
474 __inc_zone_page_state(page, NR_SHMEM);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700475 spin_unlock_irq(&mapping->tree_lock);
Nick Piggine2867812008-07-25 19:45:30 -0700476 } else {
477 page->mapping = NULL;
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700478 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700479 mem_cgroup_uncharge_cache_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700480 page_cache_release(page);
481 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800483 } else
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700484 mem_cgroup_uncharge_cache_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800485out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 return error;
487}
Nick Piggine2867812008-07-25 19:45:30 -0700488EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489
490int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400491 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700493 int ret;
494
495 /*
496 * Splice_read and readahead add shmem/tmpfs pages into the page cache
497 * before shmem_readpage has a chance to mark them as SwapBacked: they
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700498 * need to go on the anon lru below, and mem_cgroup_cache_charge
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700499 * (called in add_to_page_cache) needs to know where they're going too.
500 */
501 if (mapping_cap_swap_backed(mapping))
502 SetPageSwapBacked(page);
503
504 ret = add_to_page_cache(page, mapping, offset, gfp_mask);
505 if (ret == 0) {
506 if (page_is_file_cache(page))
507 lru_cache_add_file(page);
508 else
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700509 lru_cache_add_anon(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700510 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 return ret;
512}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300513EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514
Paul Jackson44110fe2006-03-24 03:16:04 -0800515#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700516struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800517{
Miao Xiec0ff7452010-05-24 14:32:08 -0700518 int n;
519 struct page *page;
520
Paul Jackson44110fe2006-03-24 03:16:04 -0800521 if (cpuset_do_page_mem_spread()) {
Miao Xiec0ff7452010-05-24 14:32:08 -0700522 get_mems_allowed();
523 n = cpuset_mem_spread_node();
524 page = alloc_pages_exact_node(n, gfp, 0);
525 put_mems_allowed();
526 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800527 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700528 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800529}
Nick Piggin2ae88142006-10-28 10:38:23 -0700530EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800531#endif
532
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533/*
534 * In order to wait for pages to become available there must be
535 * waitqueues associated with pages. By using a hash table of
536 * waitqueues where the bucket discipline is to maintain all
537 * waiters on the same queue and wake all when any of the pages
538 * become available, and for the woken contexts to check to be
539 * sure the appropriate page became available, this saves space
540 * at a cost of "thundering herd" phenomena during rare hash
541 * collisions.
542 */
543static wait_queue_head_t *page_waitqueue(struct page *page)
544{
545 const struct zone *zone = page_zone(page);
546
547 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
548}
549
550static inline void wake_up_page(struct page *page, int bit)
551{
552 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
553}
554
Harvey Harrison920c7a52008-02-04 22:29:26 -0800555void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556{
557 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
558
559 if (test_bit(bit_nr, &page->flags))
Jens Axboe7eaceac2011-03-10 08:52:07 +0100560 __wait_on_bit(page_waitqueue(page), &wait, sleep_on_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 TASK_UNINTERRUPTIBLE);
562}
563EXPORT_SYMBOL(wait_on_page_bit);
564
565/**
David Howells385e1ca5f2009-04-03 16:42:39 +0100566 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -0700567 * @page: Page defining the wait queue of interest
568 * @waiter: Waiter to add to the queue
David Howells385e1ca5f2009-04-03 16:42:39 +0100569 *
570 * Add an arbitrary @waiter to the wait queue for the nominated @page.
571 */
572void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
573{
574 wait_queue_head_t *q = page_waitqueue(page);
575 unsigned long flags;
576
577 spin_lock_irqsave(&q->lock, flags);
578 __add_wait_queue(q, waiter);
579 spin_unlock_irqrestore(&q->lock, flags);
580}
581EXPORT_SYMBOL_GPL(add_page_wait_queue);
582
583/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700584 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 * @page: the page
586 *
587 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
588 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
589 * mechananism between PageLocked pages and PageWriteback pages is shared.
590 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
591 *
Nick Piggin8413ac92008-10-18 20:26:59 -0700592 * The mb is necessary to enforce ordering between the clear_bit and the read
593 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800595void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596{
Nick Piggin8413ac92008-10-18 20:26:59 -0700597 VM_BUG_ON(!PageLocked(page));
598 clear_bit_unlock(PG_locked, &page->flags);
599 smp_mb__after_clear_bit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 wake_up_page(page, PG_locked);
601}
602EXPORT_SYMBOL(unlock_page);
603
Randy Dunlap485bb992006-06-23 02:03:49 -0700604/**
605 * end_page_writeback - end writeback against a page
606 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 */
608void end_page_writeback(struct page *page)
609{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700610 if (TestClearPageReclaim(page))
611 rotate_reclaimable_page(page);
612
613 if (!test_clear_page_writeback(page))
614 BUG();
615
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 smp_mb__after_clear_bit();
617 wake_up_page(page, PG_writeback);
618}
619EXPORT_SYMBOL(end_page_writeback);
620
Randy Dunlap485bb992006-06-23 02:03:49 -0700621/**
622 * __lock_page - get a lock on the page, assuming we need to sleep to get it
623 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700624 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800625void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626{
627 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
628
Jens Axboe7eaceac2011-03-10 08:52:07 +0100629 __wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 TASK_UNINTERRUPTIBLE);
631}
632EXPORT_SYMBOL(__lock_page);
633
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800634int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500635{
636 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
637
638 return __wait_on_bit_lock(page_waitqueue(page), &wait,
Jens Axboe7eaceac2011-03-10 08:52:07 +0100639 sleep_on_page_killable, TASK_KILLABLE);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500640}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300641EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500642
Michel Lespinassed065bd82010-10-26 14:21:57 -0700643int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
644 unsigned int flags)
645{
646 if (!(flags & FAULT_FLAG_ALLOW_RETRY)) {
647 __lock_page(page);
648 return 1;
649 } else {
Gleb Natapov318b2752011-03-22 16:30:51 -0700650 if (!(flags & FAULT_FLAG_RETRY_NOWAIT)) {
651 up_read(&mm->mmap_sem);
652 wait_on_page_locked(page);
653 }
Michel Lespinassed065bd82010-10-26 14:21:57 -0700654 return 0;
655 }
656}
657
Randy Dunlap485bb992006-06-23 02:03:49 -0700658/**
659 * find_get_page - find and get a page reference
660 * @mapping: the address_space to search
661 * @offset: the page index
662 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700663 * Is there a pagecache struct page at the given (mapping, offset) tuple?
664 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 */
Nick Piggina60637c2008-07-25 19:45:31 -0700666struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667{
Nick Piggina60637c2008-07-25 19:45:31 -0700668 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 struct page *page;
670
Nick Piggina60637c2008-07-25 19:45:31 -0700671 rcu_read_lock();
672repeat:
673 page = NULL;
674 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
675 if (pagep) {
676 page = radix_tree_deref_slot(pagep);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800677 if (unlikely(!page))
678 goto out;
679 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700680 goto repeat;
681
682 if (!page_cache_get_speculative(page))
683 goto repeat;
684
685 /*
686 * Has the page moved?
687 * This is part of the lockless pagecache protocol. See
688 * include/linux/pagemap.h for details.
689 */
690 if (unlikely(page != *pagep)) {
691 page_cache_release(page);
692 goto repeat;
693 }
694 }
Nick Piggin27d20fd2010-11-11 14:05:19 -0800695out:
Nick Piggina60637c2008-07-25 19:45:31 -0700696 rcu_read_unlock();
697
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 return page;
699}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700EXPORT_SYMBOL(find_get_page);
701
Randy Dunlap485bb992006-06-23 02:03:49 -0700702/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700704 * @mapping: the address_space to search
705 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706 *
707 * Locates the desired pagecache page, locks it, increments its reference
708 * count and returns its address.
709 *
710 * Returns zero if the page was not present. find_lock_page() may sleep.
711 */
Nick Piggina60637c2008-07-25 19:45:31 -0700712struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713{
714 struct page *page;
715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716repeat:
Nick Piggina60637c2008-07-25 19:45:31 -0700717 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 if (page) {
Nick Piggina60637c2008-07-25 19:45:31 -0700719 lock_page(page);
720 /* Has the page been truncated? */
721 if (unlikely(page->mapping != mapping)) {
722 unlock_page(page);
723 page_cache_release(page);
724 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 }
Nick Piggina60637c2008-07-25 19:45:31 -0700726 VM_BUG_ON(page->index != offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 return page;
729}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730EXPORT_SYMBOL(find_lock_page);
731
732/**
733 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700734 * @mapping: the page's address_space
735 * @index: the page's index into the mapping
736 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 *
738 * Locates a page in the pagecache. If the page is not present, a new page
739 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
740 * LRU list. The returned page is locked and has its reference count
741 * incremented.
742 *
743 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
744 * allocation!
745 *
746 * find_or_create_page() returns the desired page's address, or zero on
747 * memory exhaustion.
748 */
749struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700750 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751{
Nick Piggineb2be182007-10-16 01:24:57 -0700752 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 int err;
754repeat:
755 page = find_lock_page(mapping, index);
756 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700757 page = __page_cache_alloc(gfp_mask);
758 if (!page)
759 return NULL;
Nick Piggin67d58ac2009-01-06 14:40:28 -0800760 /*
761 * We want a regular kernel memory (not highmem or DMA etc)
762 * allocation for the radix tree nodes, but we need to honour
763 * the context-specific requirements the caller has asked for.
764 * GFP_RECLAIM_MASK collects those requirements.
765 */
766 err = add_to_page_cache_lru(page, mapping, index,
767 (gfp_mask & GFP_RECLAIM_MASK));
Nick Piggineb2be182007-10-16 01:24:57 -0700768 if (unlikely(err)) {
769 page_cache_release(page);
770 page = NULL;
771 if (err == -EEXIST)
772 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 return page;
776}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777EXPORT_SYMBOL(find_or_create_page);
778
779/**
780 * find_get_pages - gang pagecache lookup
781 * @mapping: The address_space to search
782 * @start: The starting page index
783 * @nr_pages: The maximum number of pages
784 * @pages: Where the resulting pages are placed
785 *
786 * find_get_pages() will search for and return a group of up to
787 * @nr_pages pages in the mapping. The pages are placed at @pages.
788 * find_get_pages() takes a reference against the returned pages.
789 *
790 * The search returns a group of mapping-contiguous pages with ascending
791 * indexes. There may be holes in the indices due to not-present pages.
792 *
793 * find_get_pages() returns the number of pages which were found.
794 */
795unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
796 unsigned int nr_pages, struct page **pages)
797{
798 unsigned int i;
799 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700800 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801
Nick Piggina60637c2008-07-25 19:45:31 -0700802 rcu_read_lock();
803restart:
804 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
805 (void ***)pages, start, nr_pages);
806 ret = 0;
807 for (i = 0; i < nr_found; i++) {
808 struct page *page;
809repeat:
810 page = radix_tree_deref_slot((void **)pages[i]);
811 if (unlikely(!page))
812 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700813
814 /*
815 * This can only trigger when the entry at index 0 moves out
816 * of or back to the root: none yet gotten, safe to restart.
817 */
Nick Piggin27d20fd2010-11-11 14:05:19 -0800818 if (radix_tree_deref_retry(page)) {
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700819 WARN_ON(start | i);
Nick Piggina60637c2008-07-25 19:45:31 -0700820 goto restart;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800821 }
Nick Piggina60637c2008-07-25 19:45:31 -0700822
823 if (!page_cache_get_speculative(page))
824 goto repeat;
825
826 /* Has the page moved? */
827 if (unlikely(page != *((void **)pages[i]))) {
828 page_cache_release(page);
829 goto repeat;
830 }
831
832 pages[ret] = page;
833 ret++;
834 }
Hugh Dickins5b280c02011-03-22 16:33:07 -0700835
836 /*
837 * If all entries were removed before we could secure them,
838 * try again, because callers stop trying once 0 is returned.
839 */
840 if (unlikely(!ret && nr_found))
841 goto restart;
Nick Piggina60637c2008-07-25 19:45:31 -0700842 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 return ret;
844}
845
Jens Axboeebf43502006-04-27 08:46:01 +0200846/**
847 * find_get_pages_contig - gang contiguous pagecache lookup
848 * @mapping: The address_space to search
849 * @index: The starting page index
850 * @nr_pages: The maximum number of pages
851 * @pages: Where the resulting pages are placed
852 *
853 * find_get_pages_contig() works exactly like find_get_pages(), except
854 * that the returned number of pages are guaranteed to be contiguous.
855 *
856 * find_get_pages_contig() returns the number of pages which were found.
857 */
858unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
859 unsigned int nr_pages, struct page **pages)
860{
861 unsigned int i;
862 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700863 unsigned int nr_found;
Jens Axboeebf43502006-04-27 08:46:01 +0200864
Nick Piggina60637c2008-07-25 19:45:31 -0700865 rcu_read_lock();
866restart:
867 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
868 (void ***)pages, index, nr_pages);
869 ret = 0;
870 for (i = 0; i < nr_found; i++) {
871 struct page *page;
872repeat:
873 page = radix_tree_deref_slot((void **)pages[i]);
874 if (unlikely(!page))
875 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700876
877 /*
878 * This can only trigger when the entry at index 0 moves out
879 * of or back to the root: none yet gotten, safe to restart.
880 */
Nick Piggin27d20fd2010-11-11 14:05:19 -0800881 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700882 goto restart;
883
Nick Piggina60637c2008-07-25 19:45:31 -0700884 if (!page_cache_get_speculative(page))
885 goto repeat;
886
887 /* Has the page moved? */
888 if (unlikely(page != *((void **)pages[i]))) {
889 page_cache_release(page);
890 goto repeat;
891 }
892
Nick Piggin9cbb4cb2011-01-13 15:45:51 -0800893 /*
894 * must check mapping and index after taking the ref.
895 * otherwise we can get both false positives and false
896 * negatives, which is just confusing to the caller.
897 */
898 if (page->mapping == NULL || page->index != index) {
899 page_cache_release(page);
900 break;
901 }
902
Nick Piggina60637c2008-07-25 19:45:31 -0700903 pages[ret] = page;
904 ret++;
Jens Axboeebf43502006-04-27 08:46:01 +0200905 index++;
906 }
Nick Piggina60637c2008-07-25 19:45:31 -0700907 rcu_read_unlock();
908 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +0200909}
David Howellsef71c152007-05-09 02:33:44 -0700910EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200911
Randy Dunlap485bb992006-06-23 02:03:49 -0700912/**
913 * find_get_pages_tag - find and return pages that match @tag
914 * @mapping: the address_space to search
915 * @index: the starting page index
916 * @tag: the tag index
917 * @nr_pages: the maximum number of pages
918 * @pages: where the resulting pages are placed
919 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700921 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 */
923unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
924 int tag, unsigned int nr_pages, struct page **pages)
925{
926 unsigned int i;
927 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700928 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700929
Nick Piggina60637c2008-07-25 19:45:31 -0700930 rcu_read_lock();
931restart:
932 nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
933 (void ***)pages, *index, nr_pages, tag);
934 ret = 0;
935 for (i = 0; i < nr_found; i++) {
936 struct page *page;
937repeat:
938 page = radix_tree_deref_slot((void **)pages[i]);
939 if (unlikely(!page))
940 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700941
942 /*
943 * This can only trigger when the entry at index 0 moves out
944 * of or back to the root: none yet gotten, safe to restart.
945 */
Nick Piggin27d20fd2010-11-11 14:05:19 -0800946 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700947 goto restart;
948
949 if (!page_cache_get_speculative(page))
950 goto repeat;
951
952 /* Has the page moved? */
953 if (unlikely(page != *((void **)pages[i]))) {
954 page_cache_release(page);
955 goto repeat;
956 }
957
958 pages[ret] = page;
959 ret++;
960 }
Hugh Dickins5b280c02011-03-22 16:33:07 -0700961
962 /*
963 * If all entries were removed before we could secure them,
964 * try again, because callers stop trying once 0 is returned.
965 */
966 if (unlikely(!ret && nr_found))
967 goto restart;
Nick Piggina60637c2008-07-25 19:45:31 -0700968 rcu_read_unlock();
969
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970 if (ret)
971 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -0700972
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 return ret;
974}
David Howellsef71c152007-05-09 02:33:44 -0700975EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976
Randy Dunlap485bb992006-06-23 02:03:49 -0700977/**
978 * grab_cache_page_nowait - returns locked page at given index in given cache
979 * @mapping: target address_space
980 * @index: the page index
981 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800982 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 * This is intended for speculative data generators, where the data can
984 * be regenerated if the page couldn't be grabbed. This routine should
985 * be safe to call while holding the lock for another page.
986 *
987 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
988 * and deadlock against the caller's locked page.
989 */
990struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -0700991grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992{
993 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994
995 if (page) {
Nick Piggin529ae9a2008-08-02 12:01:03 +0200996 if (trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 return page;
998 page_cache_release(page);
999 return NULL;
1000 }
Nick Piggin2ae88142006-10-28 10:38:23 -07001001 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
Nick Piggin67d58ac2009-01-06 14:40:28 -08001002 if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 page_cache_release(page);
1004 page = NULL;
1005 }
1006 return page;
1007}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008EXPORT_SYMBOL(grab_cache_page_nowait);
1009
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001010/*
1011 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
1012 * a _large_ part of the i/o request. Imagine the worst scenario:
1013 *
1014 * ---R__________________________________________B__________
1015 * ^ reading here ^ bad block(assume 4k)
1016 *
1017 * read(R) => miss => readahead(R...B) => media error => frustrating retries
1018 * => failing the whole request => read(R) => read(R+1) =>
1019 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
1020 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
1021 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
1022 *
1023 * It is going insane. Fix it by quickly scaling down the readahead size.
1024 */
1025static void shrink_readahead_size_eio(struct file *filp,
1026 struct file_ra_state *ra)
1027{
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001028 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001029}
1030
Randy Dunlap485bb992006-06-23 02:03:49 -07001031/**
Christoph Hellwig36e78912008-02-08 04:21:24 -08001032 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001033 * @filp: the file to read
1034 * @ppos: current file position
1035 * @desc: read_descriptor
1036 * @actor: read method
1037 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -07001039 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 *
1041 * This is really ugly. But the goto's actually try to clarify some
1042 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 */
Christoph Hellwig36e78912008-02-08 04:21:24 -08001044static void do_generic_file_read(struct file *filp, loff_t *ppos,
1045 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046{
Christoph Hellwig36e78912008-02-08 04:21:24 -08001047 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -08001049 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001050 pgoff_t index;
1051 pgoff_t last_index;
1052 pgoff_t prev_index;
1053 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -07001054 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -07001058 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
1059 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
1061 offset = *ppos & ~PAGE_CACHE_MASK;
1062
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 for (;;) {
1064 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001065 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -07001066 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 unsigned long nr, ret;
1068
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070find_page:
1071 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001072 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001073 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001074 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001075 index, last_index - index);
1076 page = find_get_page(mapping, index);
1077 if (unlikely(page == NULL))
1078 goto no_cached_page;
1079 }
1080 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001081 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001082 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001083 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001085 if (!PageUptodate(page)) {
1086 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1087 !mapping->a_ops->is_partially_uptodate)
1088 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001089 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001090 goto page_not_up_to_date;
Dave Hansen8d056cb2010-11-11 14:05:15 -08001091 /* Did it get truncated before we got the lock? */
1092 if (!page->mapping)
1093 goto page_not_up_to_date_locked;
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001094 if (!mapping->a_ops->is_partially_uptodate(page,
1095 desc, offset))
1096 goto page_not_up_to_date_locked;
1097 unlock_page(page);
1098 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001100 /*
1101 * i_size must be checked after we know the page is Uptodate.
1102 *
1103 * Checking i_size after the check allows us to calculate
1104 * the correct value for "nr", which means the zero-filled
1105 * part of the page is not copied back to userspace (unless
1106 * another truncate extends the file - this is desired though).
1107 */
1108
1109 isize = i_size_read(inode);
1110 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1111 if (unlikely(!isize || index > end_index)) {
1112 page_cache_release(page);
1113 goto out;
1114 }
1115
1116 /* nr is the maximum number of bytes to copy from this page */
1117 nr = PAGE_CACHE_SIZE;
1118 if (index == end_index) {
1119 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1120 if (nr <= offset) {
1121 page_cache_release(page);
1122 goto out;
1123 }
1124 }
1125 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126
1127 /* If users can be writing to this page using arbitrary
1128 * virtual addresses, take care about potential aliasing
1129 * before reading the page on the kernel side.
1130 */
1131 if (mapping_writably_mapped(mapping))
1132 flush_dcache_page(page);
1133
1134 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001135 * When a sequential read accesses a page several times,
1136 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 */
Jan Karaec0f1632007-05-06 14:49:25 -07001138 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 mark_page_accessed(page);
1140 prev_index = index;
1141
1142 /*
1143 * Ok, we have the page, and it's up-to-date, so
1144 * now we can copy it to user space...
1145 *
1146 * The actor routine returns how many bytes were actually used..
1147 * NOTE! This may not be the same as how much of a user buffer
1148 * we filled up (we may be padding etc), so we can only update
1149 * "pos" here (the actor routine has to update the user buffer
1150 * pointers and the remaining count).
1151 */
1152 ret = actor(desc, page, offset, nr);
1153 offset += ret;
1154 index += offset >> PAGE_CACHE_SHIFT;
1155 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001156 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157
1158 page_cache_release(page);
1159 if (ret == nr && desc->count)
1160 continue;
1161 goto out;
1162
1163page_not_up_to_date:
1164 /* Get exclusive access to the page ... */
Oleg Nesterov85462322008-06-08 21:20:43 +04001165 error = lock_page_killable(page);
1166 if (unlikely(error))
1167 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001168
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001169page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001170 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 if (!page->mapping) {
1172 unlock_page(page);
1173 page_cache_release(page);
1174 continue;
1175 }
1176
1177 /* Did somebody else fill it already? */
1178 if (PageUptodate(page)) {
1179 unlock_page(page);
1180 goto page_ok;
1181 }
1182
1183readpage:
Jeff Moyer91803b42010-05-26 11:49:40 -04001184 /*
1185 * A previous I/O error may have been due to temporary
1186 * failures, eg. multipath errors.
1187 * PG_error will be set again if readpage fails.
1188 */
1189 ClearPageError(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190 /* Start the actual read. The read will unlock the page. */
1191 error = mapping->a_ops->readpage(filp, page);
1192
Zach Brown994fc28c2005-12-15 14:28:17 -08001193 if (unlikely(error)) {
1194 if (error == AOP_TRUNCATED_PAGE) {
1195 page_cache_release(page);
1196 goto find_page;
1197 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001199 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200
1201 if (!PageUptodate(page)) {
Oleg Nesterov85462322008-06-08 21:20:43 +04001202 error = lock_page_killable(page);
1203 if (unlikely(error))
1204 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 if (!PageUptodate(page)) {
1206 if (page->mapping == NULL) {
1207 /*
Christoph Hellwig2ecdc822010-01-26 17:27:20 +01001208 * invalidate_mapping_pages got it
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 */
1210 unlock_page(page);
1211 page_cache_release(page);
1212 goto find_page;
1213 }
1214 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001215 shrink_readahead_size_eio(filp, ra);
Oleg Nesterov85462322008-06-08 21:20:43 +04001216 error = -EIO;
1217 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 }
1219 unlock_page(page);
1220 }
1221
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222 goto page_ok;
1223
1224readpage_error:
1225 /* UHHUH! A synchronous read error occurred. Report it */
1226 desc->error = error;
1227 page_cache_release(page);
1228 goto out;
1229
1230no_cached_page:
1231 /*
1232 * Ok, it wasn't cached, so we need to create a new
1233 * page..
1234 */
Nick Piggineb2be182007-10-16 01:24:57 -07001235 page = page_cache_alloc_cold(mapping);
1236 if (!page) {
1237 desc->error = -ENOMEM;
1238 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 }
Nick Piggineb2be182007-10-16 01:24:57 -07001240 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001241 index, GFP_KERNEL);
1242 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001243 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 if (error == -EEXIST)
1245 goto find_page;
1246 desc->error = error;
1247 goto out;
1248 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001249 goto readpage;
1250 }
1251
1252out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001253 ra->prev_pos = prev_index;
1254 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1255 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001257 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Krishna Kumar0c6aa262008-10-15 22:01:13 -07001258 file_accessed(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001259}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260
1261int file_read_actor(read_descriptor_t *desc, struct page *page,
1262 unsigned long offset, unsigned long size)
1263{
1264 char *kaddr;
1265 unsigned long left, count = desc->count;
1266
1267 if (size > count)
1268 size = count;
1269
1270 /*
1271 * Faults on the destination of a read are common, so do it before
1272 * taking the kmap.
1273 */
1274 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1275 kaddr = kmap_atomic(page, KM_USER0);
1276 left = __copy_to_user_inatomic(desc->arg.buf,
1277 kaddr + offset, size);
1278 kunmap_atomic(kaddr, KM_USER0);
1279 if (left == 0)
1280 goto success;
1281 }
1282
1283 /* Do it the slow way */
1284 kaddr = kmap(page);
1285 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1286 kunmap(page);
1287
1288 if (left) {
1289 size -= left;
1290 desc->error = -EFAULT;
1291 }
1292success:
1293 desc->count = count - size;
1294 desc->written += size;
1295 desc->arg.buf += size;
1296 return size;
1297}
1298
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001299/*
1300 * Performs necessary checks before doing a write
1301 * @iov: io vector request
1302 * @nr_segs: number of segments in the iovec
1303 * @count: number of bytes to write
1304 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1305 *
1306 * Adjust number of segments and amount of bytes to write (nr_segs should be
1307 * properly initialized first). Returns appropriate error code that caller
1308 * should return or zero in case that write should be allowed.
1309 */
1310int generic_segment_checks(const struct iovec *iov,
1311 unsigned long *nr_segs, size_t *count, int access_flags)
1312{
1313 unsigned long seg;
1314 size_t cnt = 0;
1315 for (seg = 0; seg < *nr_segs; seg++) {
1316 const struct iovec *iv = &iov[seg];
1317
1318 /*
1319 * If any segment has a negative length, or the cumulative
1320 * length ever wraps negative then return -EINVAL.
1321 */
1322 cnt += iv->iov_len;
1323 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1324 return -EINVAL;
1325 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1326 continue;
1327 if (seg == 0)
1328 return -EFAULT;
1329 *nr_segs = seg;
1330 cnt -= iv->iov_len; /* This segment is no good */
1331 break;
1332 }
1333 *count = cnt;
1334 return 0;
1335}
1336EXPORT_SYMBOL(generic_segment_checks);
1337
Randy Dunlap485bb992006-06-23 02:03:49 -07001338/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001339 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001340 * @iocb: kernel I/O control block
1341 * @iov: io vector request
1342 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001343 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001344 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 * This is the "read()" routine for all filesystems
1346 * that can use the page cache directly.
1347 */
1348ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001349generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1350 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351{
1352 struct file *filp = iocb->ki_filp;
1353 ssize_t retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001354 unsigned long seg = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001356 loff_t *ppos = &iocb->ki_pos;
Jens Axboe55602dd2010-06-24 15:05:37 +02001357 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358
1359 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001360 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1361 if (retval)
1362 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363
Jens Axboe55602dd2010-06-24 15:05:37 +02001364 blk_start_plug(&plug);
1365
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1367 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001368 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 struct address_space *mapping;
1370 struct inode *inode;
1371
1372 mapping = filp->f_mapping;
1373 inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 if (!count)
1375 goto out; /* skip atime */
1376 size = i_size_read(inode);
1377 if (pos < size) {
Nick Piggin48b47c52009-01-06 14:40:22 -08001378 retval = filemap_write_and_wait_range(mapping, pos,
1379 pos + iov_length(iov, nr_segs) - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07001380 if (!retval) {
1381 retval = mapping->a_ops->direct_IO(READ, iocb,
1382 iov, pos, nr_segs);
1383 }
Josef Bacik66f998f2010-05-23 11:00:54 -04001384 if (retval > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 *ppos = pos + retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001386 count -= retval;
1387 }
1388
1389 /*
1390 * Btrfs can have a short DIO read if we encounter
1391 * compressed extents, so if there was an error, or if
1392 * we've already read everything we wanted to, or if
1393 * there was a short read because we hit EOF, go ahead
1394 * and return. Otherwise fallthrough to buffered io for
1395 * the rest of the read.
1396 */
1397 if (retval < 0 || !count || *ppos >= size) {
Hugh Dickins11fa977e2008-07-23 21:27:34 -07001398 file_accessed(filp);
1399 goto out;
1400 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001401 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 }
1403
Josef Bacik66f998f2010-05-23 11:00:54 -04001404 count = retval;
Hugh Dickins11fa977e2008-07-23 21:27:34 -07001405 for (seg = 0; seg < nr_segs; seg++) {
1406 read_descriptor_t desc;
Josef Bacik66f998f2010-05-23 11:00:54 -04001407 loff_t offset = 0;
1408
1409 /*
1410 * If we did a short DIO read we need to skip the section of the
1411 * iov that we've already read data into.
1412 */
1413 if (count) {
1414 if (count > iov[seg].iov_len) {
1415 count -= iov[seg].iov_len;
1416 continue;
1417 }
1418 offset = count;
1419 count = 0;
1420 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421
Hugh Dickins11fa977e2008-07-23 21:27:34 -07001422 desc.written = 0;
Josef Bacik66f998f2010-05-23 11:00:54 -04001423 desc.arg.buf = iov[seg].iov_base + offset;
1424 desc.count = iov[seg].iov_len - offset;
Hugh Dickins11fa977e2008-07-23 21:27:34 -07001425 if (desc.count == 0)
1426 continue;
1427 desc.error = 0;
1428 do_generic_file_read(filp, ppos, &desc, file_read_actor);
1429 retval += desc.written;
1430 if (desc.error) {
1431 retval = retval ?: desc.error;
1432 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 }
Hugh Dickins11fa977e2008-07-23 21:27:34 -07001434 if (desc.count > 0)
1435 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 }
1437out:
Jens Axboe55602dd2010-06-24 15:05:37 +02001438 blk_finish_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 return retval;
1440}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441EXPORT_SYMBOL(generic_file_aio_read);
1442
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443static ssize_t
1444do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001445 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446{
1447 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1448 return -EINVAL;
1449
Wu Fengguangf7e839d2009-06-16 15:31:20 -07001450 force_page_cache_readahead(mapping, filp, index, nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 return 0;
1452}
1453
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001454SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455{
1456 ssize_t ret;
1457 struct file *file;
1458
1459 ret = -EBADF;
1460 file = fget(fd);
1461 if (file) {
1462 if (file->f_mode & FMODE_READ) {
1463 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001464 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1465 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 unsigned long len = end - start + 1;
1467 ret = do_readahead(mapping, file, start, len);
1468 }
1469 fput(file);
1470 }
1471 return ret;
1472}
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001473#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1474asmlinkage long SyS_readahead(long fd, loff_t offset, long count)
1475{
1476 return SYSC_readahead((int) fd, offset, (size_t) count);
1477}
1478SYSCALL_ALIAS(sys_readahead, SyS_readahead);
1479#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480
1481#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001482/**
1483 * page_cache_read - adds requested page to the page cache if not already there
1484 * @file: file to read
1485 * @offset: page index
1486 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 * This adds the requested page to the page cache if it isn't already there,
1488 * and schedules an I/O to read in its contents from disk.
1489 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001490static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491{
1492 struct address_space *mapping = file->f_mapping;
1493 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001494 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495
Zach Brown994fc28c2005-12-15 14:28:17 -08001496 do {
1497 page = page_cache_alloc_cold(mapping);
1498 if (!page)
1499 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500
Zach Brown994fc28c2005-12-15 14:28:17 -08001501 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1502 if (ret == 0)
1503 ret = mapping->a_ops->readpage(file, page);
1504 else if (ret == -EEXIST)
1505 ret = 0; /* losing race to add is OK */
1506
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508
Zach Brown994fc28c2005-12-15 14:28:17 -08001509 } while (ret == AOP_TRUNCATED_PAGE);
1510
1511 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512}
1513
1514#define MMAP_LOTSAMISS (100)
1515
Linus Torvaldsef00e082009-06-16 15:31:25 -07001516/*
1517 * Synchronous readahead happens when we don't even find
1518 * a page in the page cache at all.
1519 */
1520static void do_sync_mmap_readahead(struct vm_area_struct *vma,
1521 struct file_ra_state *ra,
1522 struct file *file,
1523 pgoff_t offset)
1524{
1525 unsigned long ra_pages;
1526 struct address_space *mapping = file->f_mapping;
1527
1528 /* If we don't want any read-ahead, don't bother */
1529 if (VM_RandomReadHint(vma))
1530 return;
1531
Wu Fengguang70ac23c2009-06-16 15:31:28 -07001532 if (VM_SequentialReadHint(vma) ||
1533 offset - 1 == (ra->prev_pos >> PAGE_CACHE_SHIFT)) {
Wu Fengguang7ffc59b2009-06-16 15:31:38 -07001534 page_cache_sync_readahead(mapping, ra, file, offset,
1535 ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001536 return;
1537 }
1538
1539 if (ra->mmap_miss < INT_MAX)
1540 ra->mmap_miss++;
1541
1542 /*
1543 * Do we miss much more than hit in this file? If so,
1544 * stop bothering with read-ahead. It will only hurt.
1545 */
1546 if (ra->mmap_miss > MMAP_LOTSAMISS)
1547 return;
1548
Wu Fengguangd30a1102009-06-16 15:31:30 -07001549 /*
1550 * mmap read-around
1551 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001552 ra_pages = max_sane_readahead(ra->ra_pages);
1553 if (ra_pages) {
Wu Fengguangd30a1102009-06-16 15:31:30 -07001554 ra->start = max_t(long, 0, offset - ra_pages/2);
1555 ra->size = ra_pages;
1556 ra->async_size = 0;
1557 ra_submit(ra, mapping, file);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001558 }
1559}
1560
1561/*
1562 * Asynchronous readahead happens when we find the page and PG_readahead,
1563 * so we want to possibly extend the readahead further..
1564 */
1565static void do_async_mmap_readahead(struct vm_area_struct *vma,
1566 struct file_ra_state *ra,
1567 struct file *file,
1568 struct page *page,
1569 pgoff_t offset)
1570{
1571 struct address_space *mapping = file->f_mapping;
1572
1573 /* If we don't want any read-ahead, don't bother */
1574 if (VM_RandomReadHint(vma))
1575 return;
1576 if (ra->mmap_miss > 0)
1577 ra->mmap_miss--;
1578 if (PageReadahead(page))
Wu Fengguang2fad6f52009-06-16 15:31:29 -07001579 page_cache_async_readahead(mapping, ra, file,
1580 page, offset, ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001581}
1582
Randy Dunlap485bb992006-06-23 02:03:49 -07001583/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001584 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001585 * @vma: vma in which the fault was taken
1586 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001587 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001588 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 * mapped memory region to read in file data during a page fault.
1590 *
1591 * The goto's are kind of ugly, but this streamlines the normal case of having
1592 * it in the page cache, and handles the special cases reasonably without
1593 * having a lot of duplicated code.
1594 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001595int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596{
1597 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001598 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599 struct address_space *mapping = file->f_mapping;
1600 struct file_ra_state *ra = &file->f_ra;
1601 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001602 pgoff_t offset = vmf->pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001604 pgoff_t size;
Nick Piggin83c54072007-07-19 01:47:05 -07001605 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606
Linus Torvalds1da177e2005-04-16 15:20:36 -07001607 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001608 if (offset >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001609 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612 * Do we have something in the page cache already?
1613 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001614 page = find_get_page(mapping, offset);
1615 if (likely(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001616 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07001617 * We found the page, so try async readahead before
1618 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001619 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001620 do_async_mmap_readahead(vma, ra, file, page, offset);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001621 } else {
1622 /* No page in the page cache at all */
1623 do_sync_mmap_readahead(vma, ra, file, offset);
1624 count_vm_event(PGMAJFAULT);
1625 ret = VM_FAULT_MAJOR;
1626retry_find:
Michel Lespinasseb522c942010-10-26 14:21:56 -07001627 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 if (!page)
1629 goto no_cached_page;
1630 }
1631
Michel Lespinassed88c0922010-11-02 13:05:18 -07001632 if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
1633 page_cache_release(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -07001634 return ret | VM_FAULT_RETRY;
Michel Lespinassed88c0922010-11-02 13:05:18 -07001635 }
Michel Lespinasseb522c942010-10-26 14:21:56 -07001636
1637 /* Did it get truncated? */
1638 if (unlikely(page->mapping != mapping)) {
1639 unlock_page(page);
1640 put_page(page);
1641 goto retry_find;
1642 }
1643 VM_BUG_ON(page->index != offset);
1644
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001646 * We have a locked page in the page cache, now we need to check
1647 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648 */
Nick Piggind00806b2007-07-19 01:46:57 -07001649 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 goto page_not_uptodate;
1651
Linus Torvaldsef00e082009-06-16 15:31:25 -07001652 /*
1653 * Found the page and have a reference on it.
1654 * We must recheck i_size under page lock.
1655 */
Nick Piggind00806b2007-07-19 01:46:57 -07001656 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001657 if (unlikely(offset >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001658 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001659 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001660 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001661 }
1662
Linus Torvaldsef00e082009-06-16 15:31:25 -07001663 ra->prev_pos = (loff_t)offset << PAGE_CACHE_SHIFT;
Nick Piggind0217ac2007-07-19 01:47:03 -07001664 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001665 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667no_cached_page:
1668 /*
1669 * We're only likely to ever get here if MADV_RANDOM is in
1670 * effect.
1671 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001672 error = page_cache_read(file, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673
1674 /*
1675 * The page we want has now been added to the page cache.
1676 * In the unlikely event that someone removed it in the
1677 * meantime, we'll just come back here and read it again.
1678 */
1679 if (error >= 0)
1680 goto retry_find;
1681
1682 /*
1683 * An error return from page_cache_read can result if the
1684 * system is low on memory, or a problem occurs while trying
1685 * to schedule I/O.
1686 */
1687 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001688 return VM_FAULT_OOM;
1689 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690
1691page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 /*
1693 * Umm, take care of errors if the page isn't up-to-date.
1694 * Try to re-read it _once_. We do this synchronously,
1695 * because there really aren't any performance issues here
1696 * and we need to check for errors.
1697 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001699 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001700 if (!error) {
1701 wait_on_page_locked(page);
1702 if (!PageUptodate(page))
1703 error = -EIO;
1704 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001706
1707 if (!error || error == AOP_TRUNCATED_PAGE)
1708 goto retry_find;
1709
1710 /* Things didn't work out. Return zero to tell the mm layer so. */
1711 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001712 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001713}
1714EXPORT_SYMBOL(filemap_fault);
1715
Alexey Dobriyanf0f37e2f2009-09-27 22:29:37 +04001716const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001717 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718};
1719
1720/* This is used for a general mmap of a disk file */
1721
1722int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1723{
1724 struct address_space *mapping = file->f_mapping;
1725
1726 if (!mapping->a_ops->readpage)
1727 return -ENOEXEC;
1728 file_accessed(file);
1729 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001730 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 return 0;
1732}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733
1734/*
1735 * This is for filesystems which do not implement ->writepage.
1736 */
1737int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1738{
1739 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1740 return -EINVAL;
1741 return generic_file_mmap(file, vma);
1742}
1743#else
1744int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1745{
1746 return -ENOSYS;
1747}
1748int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1749{
1750 return -ENOSYS;
1751}
1752#endif /* CONFIG_MMU */
1753
1754EXPORT_SYMBOL(generic_file_mmap);
1755EXPORT_SYMBOL(generic_file_readonly_mmap);
1756
Nick Piggin6fe69002007-05-06 14:49:04 -07001757static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001758 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001760 void *data,
1761 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762{
Nick Piggineb2be182007-10-16 01:24:57 -07001763 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 int err;
1765repeat:
1766 page = find_get_page(mapping, index);
1767 if (!page) {
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001768 page = __page_cache_alloc(gfp | __GFP_COLD);
Nick Piggineb2be182007-10-16 01:24:57 -07001769 if (!page)
1770 return ERR_PTR(-ENOMEM);
1771 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1772 if (unlikely(err)) {
1773 page_cache_release(page);
1774 if (err == -EEXIST)
1775 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001776 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777 return ERR_PTR(err);
1778 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779 err = filler(data, page);
1780 if (err < 0) {
1781 page_cache_release(page);
1782 page = ERR_PTR(err);
1783 }
1784 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785 return page;
1786}
1787
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001788static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001789 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001791 void *data,
1792 gfp_t gfp)
1793
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794{
1795 struct page *page;
1796 int err;
1797
1798retry:
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001799 page = __read_cache_page(mapping, index, filler, data, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001801 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001802 if (PageUptodate(page))
1803 goto out;
1804
1805 lock_page(page);
1806 if (!page->mapping) {
1807 unlock_page(page);
1808 page_cache_release(page);
1809 goto retry;
1810 }
1811 if (PageUptodate(page)) {
1812 unlock_page(page);
1813 goto out;
1814 }
1815 err = filler(data, page);
1816 if (err < 0) {
1817 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001818 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819 }
David Howellsc855ff32007-05-09 13:42:20 +01001820out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001821 mark_page_accessed(page);
1822 return page;
1823}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001824
1825/**
1826 * read_cache_page_async - read into page cache, fill it if needed
1827 * @mapping: the page's address_space
1828 * @index: the page index
1829 * @filler: function to perform the read
1830 * @data: destination for read data
1831 *
1832 * Same as read_cache_page, but don't wait for page to become unlocked
1833 * after submitting it to the filler.
1834 *
1835 * Read into the page cache. If a page already exists, and PageUptodate() is
1836 * not set, try to fill the page but don't wait for it to become unlocked.
1837 *
1838 * If the page does not get brought uptodate, return -EIO.
1839 */
1840struct page *read_cache_page_async(struct address_space *mapping,
1841 pgoff_t index,
1842 int (*filler)(void *,struct page*),
1843 void *data)
1844{
1845 return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
1846}
Nick Piggin6fe69002007-05-06 14:49:04 -07001847EXPORT_SYMBOL(read_cache_page_async);
1848
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001849static struct page *wait_on_page_read(struct page *page)
1850{
1851 if (!IS_ERR(page)) {
1852 wait_on_page_locked(page);
1853 if (!PageUptodate(page)) {
1854 page_cache_release(page);
1855 page = ERR_PTR(-EIO);
1856 }
1857 }
1858 return page;
1859}
1860
1861/**
1862 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
1863 * @mapping: the page's address_space
1864 * @index: the page index
1865 * @gfp: the page allocator flags to use if allocating
1866 *
1867 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
1868 * any new page allocations done using the specified allocation flags. Note
1869 * that the Radix tree operations will still use GFP_KERNEL, so you can't
1870 * expect to do this atomically or anything like that - but you can pass in
1871 * other page requirements.
1872 *
1873 * If the page does not get brought uptodate, return -EIO.
1874 */
1875struct page *read_cache_page_gfp(struct address_space *mapping,
1876 pgoff_t index,
1877 gfp_t gfp)
1878{
1879 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
1880
1881 return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp));
1882}
1883EXPORT_SYMBOL(read_cache_page_gfp);
1884
Nick Piggin6fe69002007-05-06 14:49:04 -07001885/**
1886 * read_cache_page - read into page cache, fill it if needed
1887 * @mapping: the page's address_space
1888 * @index: the page index
1889 * @filler: function to perform the read
1890 * @data: destination for read data
1891 *
1892 * Read into the page cache. If a page already exists, and PageUptodate() is
1893 * not set, try to fill the page then wait for it to become unlocked.
1894 *
1895 * If the page does not get brought uptodate, return -EIO.
1896 */
1897struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001898 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001899 int (*filler)(void *,struct page*),
1900 void *data)
1901{
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001902 return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904EXPORT_SYMBOL(read_cache_page);
1905
1906/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001907 * The logic we want is
1908 *
1909 * if suid or (sgid and xgrp)
1910 * remove privs
1911 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001912int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913{
1914 mode_t mode = dentry->d_inode->i_mode;
1915 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916
1917 /* suid always must be killed */
1918 if (unlikely(mode & S_ISUID))
1919 kill = ATTR_KILL_SUID;
1920
1921 /*
1922 * sgid without any exec bits is just a mandatory locking mark; leave
1923 * it alone. If some exec bits are set, it's a real sgid; kill it.
1924 */
1925 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1926 kill |= ATTR_KILL_SGID;
1927
Dmitri Monakhov7f5ff762008-12-01 14:34:56 -08001928 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
Jens Axboe01de85e2006-10-17 19:50:36 +02001929 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930
Jens Axboe01de85e2006-10-17 19:50:36 +02001931 return 0;
1932}
Mark Fashehd23a1472006-10-17 17:05:18 -07001933EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001934
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +02001935static int __remove_suid(struct dentry *dentry, int kill)
Jens Axboe01de85e2006-10-17 19:50:36 +02001936{
1937 struct iattr newattrs;
1938
1939 newattrs.ia_valid = ATTR_FORCE | kill;
1940 return notify_change(dentry, &newattrs);
1941}
1942
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001943int file_remove_suid(struct file *file)
Jens Axboe01de85e2006-10-17 19:50:36 +02001944{
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001945 struct dentry *dentry = file->f_path.dentry;
Serge E. Hallynb5376772007-10-16 23:31:36 -07001946 int killsuid = should_remove_suid(dentry);
1947 int killpriv = security_inode_need_killpriv(dentry);
1948 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001949
Serge E. Hallynb5376772007-10-16 23:31:36 -07001950 if (killpriv < 0)
1951 return killpriv;
1952 if (killpriv)
1953 error = security_inode_killpriv(dentry);
1954 if (!error && killsuid)
1955 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001956
Serge E. Hallynb5376772007-10-16 23:31:36 -07001957 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958}
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001959EXPORT_SYMBOL(file_remove_suid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960
Nick Piggin2f718ff2007-10-16 01:24:59 -07001961static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001962 const struct iovec *iov, size_t base, size_t bytes)
1963{
Ingo Molnarf1800532009-03-02 11:00:57 +01001964 size_t copied = 0, left = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965
1966 while (bytes) {
1967 char __user *buf = iov->iov_base + base;
1968 int copy = min(bytes, iov->iov_len - base);
1969
1970 base = 0;
Ingo Molnarf1800532009-03-02 11:00:57 +01001971 left = __copy_from_user_inatomic(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001972 copied += copy;
1973 bytes -= copy;
1974 vaddr += copy;
1975 iov++;
1976
NeilBrown01408c42006-06-25 05:47:58 -07001977 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 }
1980 return copied - left;
1981}
1982
1983/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07001984 * Copy as much as we can into the page and return the number of bytes which
André Goddard Rosaaf901ca2009-11-14 13:09:05 -02001985 * were successfully copied. If a fault is encountered then return the number of
Nick Piggin2f718ff2007-10-16 01:24:59 -07001986 * bytes which were copied.
1987 */
1988size_t iov_iter_copy_from_user_atomic(struct page *page,
1989 struct iov_iter *i, unsigned long offset, size_t bytes)
1990{
1991 char *kaddr;
1992 size_t copied;
1993
1994 BUG_ON(!in_atomic());
1995 kaddr = kmap_atomic(page, KM_USER0);
1996 if (likely(i->nr_segs == 1)) {
1997 int left;
1998 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01001999 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002000 copied = bytes - left;
2001 } else {
2002 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
2003 i->iov, i->iov_offset, bytes);
2004 }
2005 kunmap_atomic(kaddr, KM_USER0);
2006
2007 return copied;
2008}
Nick Piggin89e10782007-10-16 01:25:07 -07002009EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002010
2011/*
2012 * This has the same sideeffects and return value as
2013 * iov_iter_copy_from_user_atomic().
2014 * The difference is that it attempts to resolve faults.
2015 * Page must not be locked.
2016 */
2017size_t iov_iter_copy_from_user(struct page *page,
2018 struct iov_iter *i, unsigned long offset, size_t bytes)
2019{
2020 char *kaddr;
2021 size_t copied;
2022
2023 kaddr = kmap(page);
2024 if (likely(i->nr_segs == 1)) {
2025 int left;
2026 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01002027 left = __copy_from_user(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002028 copied = bytes - left;
2029 } else {
2030 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
2031 i->iov, i->iov_offset, bytes);
2032 }
2033 kunmap(page);
2034 return copied;
2035}
Nick Piggin89e10782007-10-16 01:25:07 -07002036EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002037
Nick Pigginf7009262008-03-10 11:43:59 -07002038void iov_iter_advance(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07002039{
Nick Pigginf7009262008-03-10 11:43:59 -07002040 BUG_ON(i->count < bytes);
2041
Nick Piggin2f718ff2007-10-16 01:24:59 -07002042 if (likely(i->nr_segs == 1)) {
2043 i->iov_offset += bytes;
Nick Pigginf7009262008-03-10 11:43:59 -07002044 i->count -= bytes;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002045 } else {
2046 const struct iovec *iov = i->iov;
2047 size_t base = i->iov_offset;
2048
Nick Piggin124d3b72008-02-02 15:01:17 +01002049 /*
2050 * The !iov->iov_len check ensures we skip over unlikely
Nick Pigginf7009262008-03-10 11:43:59 -07002051 * zero-length segments (without overruning the iovec).
Nick Piggin124d3b72008-02-02 15:01:17 +01002052 */
Linus Torvalds94ad3742008-07-30 14:45:12 -07002053 while (bytes || unlikely(i->count && !iov->iov_len)) {
Nick Pigginf7009262008-03-10 11:43:59 -07002054 int copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002055
Nick Pigginf7009262008-03-10 11:43:59 -07002056 copy = min(bytes, iov->iov_len - base);
2057 BUG_ON(!i->count || i->count < copy);
2058 i->count -= copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002059 bytes -= copy;
2060 base += copy;
2061 if (iov->iov_len == base) {
2062 iov++;
2063 base = 0;
2064 }
2065 }
2066 i->iov = iov;
2067 i->iov_offset = base;
2068 }
2069}
Nick Piggin89e10782007-10-16 01:25:07 -07002070EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002071
Nick Pigginafddba42007-10-16 01:25:01 -07002072/*
2073 * Fault in the first iovec of the given iov_iter, to a maximum length
2074 * of bytes. Returns 0 on success, or non-zero if the memory could not be
2075 * accessed (ie. because it is an invalid address).
2076 *
2077 * writev-intensive code may want this to prefault several iovecs -- that
2078 * would be possible (callers must not rely on the fact that _only_ the
2079 * first iovec will be faulted with the current implementation).
2080 */
2081int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07002082{
Nick Piggin2f718ff2007-10-16 01:24:59 -07002083 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07002084 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
2085 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002086}
Nick Piggin89e10782007-10-16 01:25:07 -07002087EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002088
2089/*
2090 * Return the count of just the current iov_iter segment.
2091 */
2092size_t iov_iter_single_seg_count(struct iov_iter *i)
2093{
2094 const struct iovec *iov = i->iov;
2095 if (i->nr_segs == 1)
2096 return i->count;
2097 else
2098 return min(i->count, iov->iov_len - i->iov_offset);
2099}
Nick Piggin89e10782007-10-16 01:25:07 -07002100EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002101
2102/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103 * Performs necessary checks before doing a write
2104 *
Randy Dunlap485bb992006-06-23 02:03:49 -07002105 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 * Returns appropriate error code that caller should return or
2107 * zero in case that write should be allowed.
2108 */
2109inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
2110{
2111 struct inode *inode = file->f_mapping->host;
Jiri Slaby59e99e52010-03-05 13:41:44 -08002112 unsigned long limit = rlimit(RLIMIT_FSIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
2114 if (unlikely(*pos < 0))
2115 return -EINVAL;
2116
Linus Torvalds1da177e2005-04-16 15:20:36 -07002117 if (!isblk) {
2118 /* FIXME: this is for backwards compatibility with 2.4 */
2119 if (file->f_flags & O_APPEND)
2120 *pos = i_size_read(inode);
2121
2122 if (limit != RLIM_INFINITY) {
2123 if (*pos >= limit) {
2124 send_sig(SIGXFSZ, current, 0);
2125 return -EFBIG;
2126 }
2127 if (*count > limit - (typeof(limit))*pos) {
2128 *count = limit - (typeof(limit))*pos;
2129 }
2130 }
2131 }
2132
2133 /*
2134 * LFS rule
2135 */
2136 if (unlikely(*pos + *count > MAX_NON_LFS &&
2137 !(file->f_flags & O_LARGEFILE))) {
2138 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139 return -EFBIG;
2140 }
2141 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2142 *count = MAX_NON_LFS - (unsigned long)*pos;
2143 }
2144 }
2145
2146 /*
2147 * Are we about to exceed the fs block limit ?
2148 *
2149 * If we have written data it becomes a short write. If we have
2150 * exceeded without writing data we send a signal and return EFBIG.
2151 * Linus frestrict idea will clean these up nicely..
2152 */
2153 if (likely(!isblk)) {
2154 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2155 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 return -EFBIG;
2157 }
2158 /* zero-length writes at ->s_maxbytes are OK */
2159 }
2160
2161 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2162 *count = inode->i_sb->s_maxbytes - *pos;
2163 } else {
David Howells93614012006-09-30 20:45:40 +02002164#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 loff_t isize;
2166 if (bdev_read_only(I_BDEV(inode)))
2167 return -EPERM;
2168 isize = i_size_read(inode);
2169 if (*pos >= isize) {
2170 if (*count || *pos > isize)
2171 return -ENOSPC;
2172 }
2173
2174 if (*pos + *count > isize)
2175 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002176#else
2177 return -EPERM;
2178#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 }
2180 return 0;
2181}
2182EXPORT_SYMBOL(generic_write_checks);
2183
Nick Pigginafddba42007-10-16 01:25:01 -07002184int pagecache_write_begin(struct file *file, struct address_space *mapping,
2185 loff_t pos, unsigned len, unsigned flags,
2186 struct page **pagep, void **fsdata)
2187{
2188 const struct address_space_operations *aops = mapping->a_ops;
2189
Nick Piggin4e02ed42008-10-29 14:00:55 -07002190 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002191 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002192}
2193EXPORT_SYMBOL(pagecache_write_begin);
2194
2195int pagecache_write_end(struct file *file, struct address_space *mapping,
2196 loff_t pos, unsigned len, unsigned copied,
2197 struct page *page, void *fsdata)
2198{
2199 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002200
Nick Piggin4e02ed42008-10-29 14:00:55 -07002201 mark_page_accessed(page);
2202 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002203}
2204EXPORT_SYMBOL(pagecache_write_end);
2205
Linus Torvalds1da177e2005-04-16 15:20:36 -07002206ssize_t
2207generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2208 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2209 size_t count, size_t ocount)
2210{
2211 struct file *file = iocb->ki_filp;
2212 struct address_space *mapping = file->f_mapping;
2213 struct inode *inode = mapping->host;
2214 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002215 size_t write_len;
2216 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002217
2218 if (count != ocount)
2219 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2220
Christoph Hellwiga969e902008-07-23 21:27:04 -07002221 write_len = iov_length(iov, *nr_segs);
2222 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002223
Nick Piggin48b47c52009-01-06 14:40:22 -08002224 written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002225 if (written)
2226 goto out;
2227
2228 /*
2229 * After a write we want buffered reads to be sure to go to disk to get
2230 * the new data. We invalidate clean cached page from the region we're
2231 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002232 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002233 */
2234 if (mapping->nrpages) {
2235 written = invalidate_inode_pages2_range(mapping,
2236 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002237 /*
2238 * If a page can not be invalidated, return 0 to fall back
2239 * to buffered write.
2240 */
2241 if (written) {
2242 if (written == -EBUSY)
2243 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002244 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002245 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002246 }
2247
2248 written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2249
2250 /*
2251 * Finally, try again to invalidate clean pages which might have been
2252 * cached by non-direct readahead, or faulted in by get_user_pages()
2253 * if the source of the write was an mmap'ed region of the file
2254 * we're writing. Either one is a pretty crazy thing to do,
2255 * so we don't support it 100%. If this invalidation
2256 * fails, tough, the write still worked...
2257 */
2258 if (mapping->nrpages) {
2259 invalidate_inode_pages2_range(mapping,
2260 pos >> PAGE_CACHE_SHIFT, end);
2261 }
2262
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 if (written > 0) {
Namhyung Kim01166512010-10-26 14:21:58 -07002264 pos += written;
2265 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2266 i_size_write(inode, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267 mark_inode_dirty(inode);
2268 }
Namhyung Kim01166512010-10-26 14:21:58 -07002269 *ppos = pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002271out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272 return written;
2273}
2274EXPORT_SYMBOL(generic_file_direct_write);
2275
Nick Piggineb2be182007-10-16 01:24:57 -07002276/*
2277 * Find or create a page at the given pagecache position. Return the locked
2278 * page. This function is specifically for buffered writes.
2279 */
Nick Piggin54566b22009-01-04 12:00:53 -08002280struct page *grab_cache_page_write_begin(struct address_space *mapping,
2281 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07002282{
2283 int status;
2284 struct page *page;
Nick Piggin54566b22009-01-04 12:00:53 -08002285 gfp_t gfp_notmask = 0;
2286 if (flags & AOP_FLAG_NOFS)
2287 gfp_notmask = __GFP_FS;
Nick Piggineb2be182007-10-16 01:24:57 -07002288repeat:
2289 page = find_lock_page(mapping, index);
Steven Rostedtc585a262011-01-13 15:46:18 -08002290 if (page)
Nick Piggineb2be182007-10-16 01:24:57 -07002291 return page;
2292
Nick Piggin54566b22009-01-04 12:00:53 -08002293 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002294 if (!page)
2295 return NULL;
Nick Piggin54566b22009-01-04 12:00:53 -08002296 status = add_to_page_cache_lru(page, mapping, index,
2297 GFP_KERNEL & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002298 if (unlikely(status)) {
2299 page_cache_release(page);
2300 if (status == -EEXIST)
2301 goto repeat;
2302 return NULL;
2303 }
2304 return page;
2305}
Nick Piggin54566b22009-01-04 12:00:53 -08002306EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07002307
Nick Pigginafddba42007-10-16 01:25:01 -07002308static ssize_t generic_perform_write(struct file *file,
2309 struct iov_iter *i, loff_t pos)
2310{
2311 struct address_space *mapping = file->f_mapping;
2312 const struct address_space_operations *a_ops = mapping->a_ops;
2313 long status = 0;
2314 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002315 unsigned int flags = 0;
2316
2317 /*
2318 * Copies from kernel address space cannot fail (NFSD is a big user).
2319 */
2320 if (segment_eq(get_fs(), KERNEL_DS))
2321 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002322
2323 do {
2324 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07002325 unsigned long offset; /* Offset into pagecache page */
2326 unsigned long bytes; /* Bytes to write to page */
2327 size_t copied; /* Bytes copied from user */
2328 void *fsdata;
2329
2330 offset = (pos & (PAGE_CACHE_SIZE - 1));
Nick Pigginafddba42007-10-16 01:25:01 -07002331 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2332 iov_iter_count(i));
2333
2334again:
2335
2336 /*
2337 * Bring in the user page that we will copy from _first_.
2338 * Otherwise there's a nasty deadlock on copying from the
2339 * same page as we're writing to, without it being marked
2340 * up-to-date.
2341 *
2342 * Not only is this an optimisation, but it is also required
2343 * to check that the address is actually valid, when atomic
2344 * usercopies are used, below.
2345 */
2346 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2347 status = -EFAULT;
2348 break;
2349 }
2350
Nick Piggin674b8922007-10-16 01:25:03 -07002351 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002352 &page, &fsdata);
2353 if (unlikely(status))
2354 break;
2355
anfei zhou931e80e2010-02-02 13:44:02 -08002356 if (mapping_writably_mapped(mapping))
2357 flush_dcache_page(page);
2358
Nick Pigginafddba42007-10-16 01:25:01 -07002359 pagefault_disable();
2360 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2361 pagefault_enable();
2362 flush_dcache_page(page);
2363
Josef Bacikc8236db2009-07-05 12:08:18 -07002364 mark_page_accessed(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002365 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2366 page, fsdata);
2367 if (unlikely(status < 0))
2368 break;
2369 copied = status;
2370
2371 cond_resched();
2372
Nick Piggin124d3b72008-02-02 15:01:17 +01002373 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002374 if (unlikely(copied == 0)) {
2375 /*
2376 * If we were unable to copy any data at all, we must
2377 * fall back to a single segment length write.
2378 *
2379 * If we didn't fallback here, we could livelock
2380 * because not all segments in the iov can be copied at
2381 * once without a pagefault.
2382 */
2383 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2384 iov_iter_single_seg_count(i));
2385 goto again;
2386 }
Nick Pigginafddba42007-10-16 01:25:01 -07002387 pos += copied;
2388 written += copied;
2389
2390 balance_dirty_pages_ratelimited(mapping);
2391
2392 } while (iov_iter_count(i));
2393
2394 return written ? written : status;
2395}
2396
2397ssize_t
2398generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2399 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2400 size_t count, ssize_t written)
2401{
2402 struct file *file = iocb->ki_filp;
Nick Pigginafddba42007-10-16 01:25:01 -07002403 ssize_t status;
2404 struct iov_iter i;
2405
2406 iov_iter_init(&i, iov, nr_segs, count, written);
Nick Piggin4e02ed42008-10-29 14:00:55 -07002407 status = generic_perform_write(file, &i, pos);
Nick Pigginafddba42007-10-16 01:25:01 -07002408
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002410 written += status;
2411 *ppos = pos + status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002412 }
2413
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414 return written ? written : status;
2415}
2416EXPORT_SYMBOL(generic_file_buffered_write);
2417
Jan Karae4dd9de2009-08-17 18:10:06 +02002418/**
2419 * __generic_file_aio_write - write data to a file
2420 * @iocb: IO state structure (file, offset, etc.)
2421 * @iov: vector with data to write
2422 * @nr_segs: number of segments in the vector
2423 * @ppos: position where to write
2424 *
2425 * This function does all the work needed for actually writing data to a
2426 * file. It does all basic checks, removes SUID from the file, updates
2427 * modification times and calls proper subroutines depending on whether we
2428 * do direct IO or a standard buffered write.
2429 *
2430 * It expects i_mutex to be grabbed unless we work on a block device or similar
2431 * object which does not need locking at all.
2432 *
2433 * This function does *not* take care of syncing data in case of O_SYNC write.
2434 * A caller has to handle it. This is mainly due to the fact that we want to
2435 * avoid syncing under i_mutex.
2436 */
2437ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2438 unsigned long nr_segs, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002439{
2440 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002441 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002442 size_t ocount; /* original count */
2443 size_t count; /* after file limit checks */
2444 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445 loff_t pos;
2446 ssize_t written;
2447 ssize_t err;
2448
2449 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002450 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2451 if (err)
2452 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002453
2454 count = ocount;
2455 pos = *ppos;
2456
2457 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2458
2459 /* We can write back this queue in page reclaim */
2460 current->backing_dev_info = mapping->backing_dev_info;
2461 written = 0;
2462
2463 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2464 if (err)
2465 goto out;
2466
2467 if (count == 0)
2468 goto out;
2469
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002470 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471 if (err)
2472 goto out;
2473
Christoph Hellwig870f4812006-01-09 20:52:01 -08002474 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002475
2476 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2477 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002478 loff_t endbyte;
2479 ssize_t written_buffered;
2480
2481 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2482 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483 if (written < 0 || written == count)
2484 goto out;
2485 /*
2486 * direct-io write to a hole: fall through to buffered I/O
2487 * for completing the rest of the request.
2488 */
2489 pos += written;
2490 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002491 written_buffered = generic_file_buffered_write(iocb, iov,
2492 nr_segs, pos, ppos, count,
2493 written);
2494 /*
2495 * If generic_file_buffered_write() retuned a synchronous error
2496 * then we want to return the number of bytes which were
2497 * direct-written, or the error code if that was zero. Note
2498 * that this differs from normal direct-io semantics, which
2499 * will return -EFOO even if some bytes were written.
2500 */
2501 if (written_buffered < 0) {
2502 err = written_buffered;
2503 goto out;
2504 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002506 /*
2507 * We need to ensure that the page cache pages are written to
2508 * disk and invalidated to preserve the expected O_DIRECT
2509 * semantics.
2510 */
2511 endbyte = pos + written_buffered - written - 1;
Christoph Hellwigc05c4ed2009-09-23 15:07:30 +02002512 err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002513 if (err == 0) {
2514 written = written_buffered;
2515 invalidate_mapping_pages(mapping,
2516 pos >> PAGE_CACHE_SHIFT,
2517 endbyte >> PAGE_CACHE_SHIFT);
2518 } else {
2519 /*
2520 * We don't know how much we wrote, so just return
2521 * the number of bytes which were direct-written
2522 */
2523 }
2524 } else {
2525 written = generic_file_buffered_write(iocb, iov, nr_segs,
2526 pos, ppos, count, written);
2527 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002528out:
2529 current->backing_dev_info = NULL;
2530 return written ? written : err;
2531}
Jan Karae4dd9de2009-08-17 18:10:06 +02002532EXPORT_SYMBOL(__generic_file_aio_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533
Jan Karae4dd9de2009-08-17 18:10:06 +02002534/**
2535 * generic_file_aio_write - write data to a file
2536 * @iocb: IO state structure
2537 * @iov: vector with data to write
2538 * @nr_segs: number of segments in the vector
2539 * @pos: position in file where to write
2540 *
2541 * This is a wrapper around __generic_file_aio_write() to be used by most
2542 * filesystems. It takes care of syncing the file in case of O_SYNC file
2543 * and acquires i_mutex as needed.
2544 */
Badari Pulavarty027445c2006-09-30 23:28:46 -07002545ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2546 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002547{
2548 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02002549 struct inode *inode = file->f_mapping->host;
Jens Axboe55602dd2010-06-24 15:05:37 +02002550 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002551 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552
2553 BUG_ON(iocb->ki_pos != pos);
2554
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002555 mutex_lock(&inode->i_mutex);
Jens Axboe55602dd2010-06-24 15:05:37 +02002556 blk_start_plug(&plug);
Jan Karae4dd9de2009-08-17 18:10:06 +02002557 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002558 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002559
Jan Kara148f9482009-08-17 19:52:36 +02002560 if (ret > 0 || ret == -EIOCBQUEUED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002561 ssize_t err;
2562
Jan Kara148f9482009-08-17 19:52:36 +02002563 err = generic_write_sync(file, pos, ret);
Jan Karac7b50db2009-08-18 16:18:20 +02002564 if (err < 0 && ret > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565 ret = err;
2566 }
Jens Axboe55602dd2010-06-24 15:05:37 +02002567 blk_finish_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 return ret;
2569}
2570EXPORT_SYMBOL(generic_file_aio_write);
2571
David Howellscf9a2ae2006-08-29 19:05:54 +01002572/**
2573 * try_to_release_page() - release old fs-specific metadata on a page
2574 *
2575 * @page: the page which the kernel is trying to free
2576 * @gfp_mask: memory allocation flags (and I/O mode)
2577 *
2578 * The address_space is to try to release any data against the page
2579 * (presumably at page->private). If the release was successful, return `1'.
2580 * Otherwise return zero.
2581 *
David Howells266cf652009-04-03 16:42:36 +01002582 * This may also be called if PG_fscache is set on a page, indicating that the
2583 * page is known to the local caching routines.
2584 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002585 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fddf2008-07-25 01:46:22 -07002586 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002587 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002588 */
2589int try_to_release_page(struct page *page, gfp_t gfp_mask)
2590{
2591 struct address_space * const mapping = page->mapping;
2592
2593 BUG_ON(!PageLocked(page));
2594 if (PageWriteback(page))
2595 return 0;
2596
2597 if (mapping && mapping->a_ops->releasepage)
2598 return mapping->a_ops->releasepage(page, gfp_mask);
2599 return try_to_free_buffers(page);
2600}
2601
2602EXPORT_SYMBOL(try_to_release_page);