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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() */
Dan Magenheimerc515e1f2011-05-26 10:01:43 -060037#include <linux/cleancache.h>
Nick Piggin0f8053a2006-03-22 00:08:33 -080038#include "internal.h"
39
Linus Torvalds1da177e2005-04-16 15:20:36 -070040/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 * FIXME: remove all knowledge of the buffer layer from the core VM
42 */
Jan Kara148f9482009-08-17 19:52:36 +020043#include <linux/buffer_head.h> /* for try_to_free_buffers */
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <asm/mman.h>
46
47/*
48 * Shared mappings implemented 30.11.1994. It's not fully working yet,
49 * though.
50 *
51 * Shared mappings now work. 15.8.1995 Bruno.
52 *
53 * finished 'unifying' the page and buffer cache and SMP-threaded the
54 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
55 *
56 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
57 */
58
59/*
60 * Lock ordering:
61 *
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070062 * ->i_mmap_mutex (truncate_pagecache)
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070064 * ->swap_lock (exclusive_swap_page, others)
65 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080067 * ->i_mutex
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070068 * ->i_mmap_mutex (truncate->unmap_mapping_range)
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 *
70 * ->mmap_sem
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070071 * ->i_mmap_mutex
Hugh Dickinsb8072f02005-10-29 18:16:41 -070072 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
74 *
75 * ->mmap_sem
76 * ->lock_page (access_process_vm)
77 *
Nick Piggin82591e62006-10-19 23:29:10 -070078 * ->i_mutex (generic_file_buffered_write)
79 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080081 * ->i_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 * ->i_alloc_sem (various)
83 *
Dave Chinnera66979a2011-03-22 22:23:41 +110084 * inode_wb_list_lock
85 * sb_lock (fs/fs-writeback.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 * ->mapping->tree_lock (__sync_single_inode)
87 *
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070088 * ->i_mmap_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 * ->anon_vma.lock (vma_adjust)
90 *
91 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -070092 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -070094 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -070095 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 * ->private_lock (try_to_unmap_one)
97 * ->tree_lock (try_to_unmap_one)
98 * ->zone.lru_lock (follow_page->mark_page_accessed)
Nick Piggin053837f2006-01-18 17:42:27 -080099 * ->zone.lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 * ->private_lock (page_remove_rmap->set_page_dirty)
101 * ->tree_lock (page_remove_rmap->set_page_dirty)
Dave Chinnera66979a2011-03-22 22:23:41 +1100102 * inode_wb_list_lock (page_remove_rmap->set_page_dirty)
Dave Chinner250df6e2011-03-22 22:23:36 +1100103 * ->inode->i_lock (page_remove_rmap->set_page_dirty)
Dave Chinnera66979a2011-03-22 22:23:41 +1100104 * inode_wb_list_lock (zap_pte_range->set_page_dirty)
Dave Chinner250df6e2011-03-22 22:23:36 +1100105 * ->inode->i_lock (zap_pte_range->set_page_dirty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
107 *
Andi Kleen6a460792009-09-16 11:50:15 +0200108 * (code doesn't rely on that order, so you could switch it around)
109 * ->tasklist_lock (memory_failure, collect_procs_ao)
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700110 * ->i_mmap_mutex
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 */
112
113/*
Minchan Kime64a7822011-03-22 16:32:44 -0700114 * Delete a page from the page cache and free it. Caller has to make
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700116 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 */
Minchan Kime64a7822011-03-22 16:32:44 -0700118void __delete_from_page_cache(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119{
120 struct address_space *mapping = page->mapping;
121
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600122 /*
123 * if we're uptodate, flush out into the cleancache, otherwise
124 * invalidate any existing cleancache entries. We can't leave
125 * stale data around in the cleancache once our page is gone
126 */
127 if (PageUptodate(page) && PageMappedToDisk(page))
128 cleancache_put_page(page);
129 else
130 cleancache_flush_page(mapping, page);
131
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 radix_tree_delete(&mapping->page_tree, page->index);
133 page->mapping = NULL;
134 mapping->nrpages--;
Christoph Lameter347ce432006-06-30 01:55:35 -0700135 __dec_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700136 if (PageSwapBacked(page))
137 __dec_zone_page_state(page, NR_SHMEM);
Nick Piggin45426812007-07-15 23:38:12 -0700138 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800139
140 /*
141 * Some filesystems seem to re-dirty the page even after
142 * the VM has canceled the dirty bit (eg ext3 journaling).
143 *
144 * Fix it up by doing a final dirty accounting check after
145 * having removed the page entirely.
146 */
147 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
148 dec_zone_page_state(page, NR_FILE_DIRTY);
149 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
150 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151}
152
Minchan Kim702cfbf2011-03-22 16:32:43 -0700153/**
154 * delete_from_page_cache - delete page from page cache
155 * @page: the page which the kernel is trying to remove from page cache
156 *
157 * This must be called only on pages that have been verified to be in the page
158 * cache and locked. It will never put the page into the free list, the caller
159 * has a reference on the page.
160 */
161void delete_from_page_cache(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162{
163 struct address_space *mapping = page->mapping;
Linus Torvalds6072d132010-12-01 13:35:19 -0500164 void (*freepage)(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
Matt Mackallcd7619d2005-05-01 08:59:01 -0700166 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167
Linus Torvalds6072d132010-12-01 13:35:19 -0500168 freepage = mapping->a_ops->freepage;
Nick Piggin19fd6232008-07-25 19:45:32 -0700169 spin_lock_irq(&mapping->tree_lock);
Minchan Kime64a7822011-03-22 16:32:44 -0700170 __delete_from_page_cache(page);
Nick Piggin19fd6232008-07-25 19:45:32 -0700171 spin_unlock_irq(&mapping->tree_lock);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700172 mem_cgroup_uncharge_cache_page(page);
Linus Torvalds6072d132010-12-01 13:35:19 -0500173
174 if (freepage)
175 freepage(page);
Minchan Kim97cecb52011-03-22 16:30:53 -0700176 page_cache_release(page);
177}
178EXPORT_SYMBOL(delete_from_page_cache);
179
Jens Axboe7eaceac2011-03-10 08:52:07 +0100180static int sleep_on_page(void *word)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 io_schedule();
183 return 0;
184}
185
Jens Axboe7eaceac2011-03-10 08:52:07 +0100186static int sleep_on_page_killable(void *word)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500187{
Jens Axboe7eaceac2011-03-10 08:52:07 +0100188 sleep_on_page(word);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500189 return fatal_signal_pending(current) ? -EINTR : 0;
190}
191
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700193 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700194 * @mapping: address space structure to write
195 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800196 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700197 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700199 * Start writeback against all of a mapping's dirty pages that lie
200 * within the byte offsets <start, end> inclusive.
201 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700203 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 * these two operations is that if a dirty page/buffer is encountered, it must
205 * be waited upon, and not just skipped over.
206 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800207int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
208 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209{
210 int ret;
211 struct writeback_control wbc = {
212 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800213 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700214 .range_start = start,
215 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 };
217
218 if (!mapping_cap_writeback_dirty(mapping))
219 return 0;
220
221 ret = do_writepages(mapping, &wbc);
222 return ret;
223}
224
225static inline int __filemap_fdatawrite(struct address_space *mapping,
226 int sync_mode)
227{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700228 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229}
230
231int filemap_fdatawrite(struct address_space *mapping)
232{
233 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
234}
235EXPORT_SYMBOL(filemap_fdatawrite);
236
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400237int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800238 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239{
240 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
241}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400242EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243
Randy Dunlap485bb992006-06-23 02:03:49 -0700244/**
245 * filemap_flush - mostly a non-blocking flush
246 * @mapping: target address_space
247 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 * This is a mostly non-blocking flush. Not suitable for data-integrity
249 * purposes - I/O may not be started against all dirty pages.
250 */
251int filemap_flush(struct address_space *mapping)
252{
253 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
254}
255EXPORT_SYMBOL(filemap_flush);
256
Randy Dunlap485bb992006-06-23 02:03:49 -0700257/**
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200258 * filemap_fdatawait_range - wait for writeback to complete
259 * @mapping: address space structure to wait for
260 * @start_byte: offset in bytes where the range starts
261 * @end_byte: offset in bytes where the range ends (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -0700262 *
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200263 * Walk the list of under-writeback pages of the given address space
264 * in the given range and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 */
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200266int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
267 loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268{
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200269 pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
270 pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 struct pagevec pvec;
272 int nr_pages;
273 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200275 if (end_byte < start_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 return 0;
277
278 pagevec_init(&pvec, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 while ((index <= end) &&
280 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
281 PAGECACHE_TAG_WRITEBACK,
282 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
283 unsigned i;
284
285 for (i = 0; i < nr_pages; i++) {
286 struct page *page = pvec.pages[i];
287
288 /* until radix tree lookup accepts end_index */
289 if (page->index > end)
290 continue;
291
292 wait_on_page_writeback(page);
Rik van Riel212260a2011-01-13 15:46:06 -0800293 if (TestClearPageError(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 ret = -EIO;
295 }
296 pagevec_release(&pvec);
297 cond_resched();
298 }
299
300 /* Check for outstanding write errors */
301 if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
302 ret = -ENOSPC;
303 if (test_and_clear_bit(AS_EIO, &mapping->flags))
304 ret = -EIO;
305
306 return ret;
307}
Jan Karad3bccb6f2009-08-17 19:30:27 +0200308EXPORT_SYMBOL(filemap_fdatawait_range);
309
310/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700311 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700313 *
314 * Walk the list of under-writeback pages of the given address space
315 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316 */
317int filemap_fdatawait(struct address_space *mapping)
318{
319 loff_t i_size = i_size_read(mapping->host);
320
321 if (i_size == 0)
322 return 0;
323
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200324 return filemap_fdatawait_range(mapping, 0, i_size - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325}
326EXPORT_SYMBOL(filemap_fdatawait);
327
328int filemap_write_and_wait(struct address_space *mapping)
329{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800330 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
332 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800333 err = filemap_fdatawrite(mapping);
334 /*
335 * Even if the above returned error, the pages may be
336 * written partially (e.g. -ENOSPC), so we wait for it.
337 * But the -EIO is special case, it may indicate the worst
338 * thing (e.g. bug) happened, so we avoid waiting for it.
339 */
340 if (err != -EIO) {
341 int err2 = filemap_fdatawait(mapping);
342 if (!err)
343 err = err2;
344 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800346 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800348EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349
Randy Dunlap485bb992006-06-23 02:03:49 -0700350/**
351 * filemap_write_and_wait_range - write out & wait on a file range
352 * @mapping: the address_space for the pages
353 * @lstart: offset in bytes where the range starts
354 * @lend: offset in bytes where the range ends (inclusive)
355 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800356 * Write out and wait upon file offsets lstart->lend, inclusive.
357 *
358 * Note that `lend' is inclusive (describes the last byte to be written) so
359 * that this function can be used to write to the very end-of-file (end = -1).
360 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361int filemap_write_and_wait_range(struct address_space *mapping,
362 loff_t lstart, loff_t lend)
363{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800364 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365
366 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800367 err = __filemap_fdatawrite_range(mapping, lstart, lend,
368 WB_SYNC_ALL);
369 /* See comment of filemap_write_and_wait() */
370 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200371 int err2 = filemap_fdatawait_range(mapping,
372 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800373 if (!err)
374 err = err2;
375 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800377 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378}
Chris Masonf6995582009-04-15 13:22:37 -0400379EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380
Randy Dunlap485bb992006-06-23 02:03:49 -0700381/**
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700382 * replace_page_cache_page - replace a pagecache page with a new one
383 * @old: page to be replaced
384 * @new: page to replace with
385 * @gfp_mask: allocation mode
386 *
387 * This function replaces a page in the pagecache with a new one. On
388 * success it acquires the pagecache reference for the new page and
389 * drops it for the old page. Both the old and new pages must be
390 * locked. This function does not add the new page to the LRU, the
391 * caller must do that.
392 *
393 * The remove + add is atomic. The only way this function can fail is
394 * memory allocation failure.
395 */
396int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
397{
398 int error;
399 struct mem_cgroup *memcg = NULL;
400
401 VM_BUG_ON(!PageLocked(old));
402 VM_BUG_ON(!PageLocked(new));
403 VM_BUG_ON(new->mapping);
404
405 /*
406 * This is not page migration, but prepare_migration and
407 * end_migration does enough work for charge replacement.
408 *
409 * In the longer term we probably want a specialized function
410 * for moving the charge from old to new in a more efficient
411 * manner.
412 */
413 error = mem_cgroup_prepare_migration(old, new, &memcg, gfp_mask);
414 if (error)
415 return error;
416
417 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
418 if (!error) {
419 struct address_space *mapping = old->mapping;
420 void (*freepage)(struct page *);
421
422 pgoff_t offset = old->index;
423 freepage = mapping->a_ops->freepage;
424
425 page_cache_get(new);
426 new->mapping = mapping;
427 new->index = offset;
428
429 spin_lock_irq(&mapping->tree_lock);
Minchan Kime64a7822011-03-22 16:32:44 -0700430 __delete_from_page_cache(old);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700431 error = radix_tree_insert(&mapping->page_tree, offset, new);
432 BUG_ON(error);
433 mapping->nrpages++;
434 __inc_zone_page_state(new, NR_FILE_PAGES);
435 if (PageSwapBacked(new))
436 __inc_zone_page_state(new, NR_SHMEM);
437 spin_unlock_irq(&mapping->tree_lock);
438 radix_tree_preload_end();
439 if (freepage)
440 freepage(old);
441 page_cache_release(old);
442 mem_cgroup_end_migration(memcg, old, new, true);
443 } else {
444 mem_cgroup_end_migration(memcg, old, new, false);
445 }
446
447 return error;
448}
449EXPORT_SYMBOL_GPL(replace_page_cache_page);
450
451/**
Nick Piggine2867812008-07-25 19:45:30 -0700452 * add_to_page_cache_locked - add a locked page to the pagecache
Randy Dunlap485bb992006-06-23 02:03:49 -0700453 * @page: page to add
454 * @mapping: the page's address_space
455 * @offset: page index
456 * @gfp_mask: page allocation mode
457 *
Nick Piggine2867812008-07-25 19:45:30 -0700458 * This function is used to add a page to the pagecache. It must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 * This function does not add the page to the LRU. The caller must do that.
460 */
Nick Piggine2867812008-07-25 19:45:30 -0700461int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400462 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463{
Nick Piggine2867812008-07-25 19:45:30 -0700464 int error;
465
466 VM_BUG_ON(!PageLocked(page));
467
468 error = mem_cgroup_cache_charge(page, current->mm,
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -0800469 gfp_mask & GFP_RECLAIM_MASK);
Balbir Singh35c754d2008-02-07 00:14:05 -0800470 if (error)
471 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
Balbir Singh35c754d2008-02-07 00:14:05 -0800473 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474 if (error == 0) {
Nick Piggine2867812008-07-25 19:45:30 -0700475 page_cache_get(page);
476 page->mapping = mapping;
477 page->index = offset;
478
Nick Piggin19fd6232008-07-25 19:45:32 -0700479 spin_lock_irq(&mapping->tree_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 error = radix_tree_insert(&mapping->page_tree, offset, page);
Nick Piggine2867812008-07-25 19:45:30 -0700481 if (likely(!error)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482 mapping->nrpages++;
Christoph Lameter347ce432006-06-30 01:55:35 -0700483 __inc_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700484 if (PageSwapBacked(page))
485 __inc_zone_page_state(page, NR_SHMEM);
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700486 spin_unlock_irq(&mapping->tree_lock);
Nick Piggine2867812008-07-25 19:45:30 -0700487 } else {
488 page->mapping = NULL;
Daisuke Nishimurae767e052009-05-28 14:34:28 -0700489 spin_unlock_irq(&mapping->tree_lock);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700490 mem_cgroup_uncharge_cache_page(page);
Nick Piggine2867812008-07-25 19:45:30 -0700491 page_cache_release(page);
492 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 radix_tree_preload_end();
Balbir Singh35c754d2008-02-07 00:14:05 -0800494 } else
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700495 mem_cgroup_uncharge_cache_page(page);
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800496out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497 return error;
498}
Nick Piggine2867812008-07-25 19:45:30 -0700499EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500
501int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400502 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700503{
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700504 int ret;
505
506 /*
507 * Splice_read and readahead add shmem/tmpfs pages into the page cache
508 * before shmem_readpage has a chance to mark them as SwapBacked: they
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700509 * need to go on the anon lru below, and mem_cgroup_cache_charge
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700510 * (called in add_to_page_cache) needs to know where they're going too.
511 */
512 if (mapping_cap_swap_backed(mapping))
513 SetPageSwapBacked(page);
514
515 ret = add_to_page_cache(page, mapping, offset, gfp_mask);
516 if (ret == 0) {
517 if (page_is_file_cache(page))
518 lru_cache_add_file(page);
519 else
KOSAKI Motohiroe9d6c152010-05-24 14:31:48 -0700520 lru_cache_add_anon(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700521 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522 return ret;
523}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300524EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
Paul Jackson44110fe2006-03-24 03:16:04 -0800526#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700527struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800528{
Miao Xiec0ff7452010-05-24 14:32:08 -0700529 int n;
530 struct page *page;
531
Paul Jackson44110fe2006-03-24 03:16:04 -0800532 if (cpuset_do_page_mem_spread()) {
Miao Xiec0ff7452010-05-24 14:32:08 -0700533 get_mems_allowed();
534 n = cpuset_mem_spread_node();
535 page = alloc_pages_exact_node(n, gfp, 0);
536 put_mems_allowed();
537 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800538 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700539 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800540}
Nick Piggin2ae88142006-10-28 10:38:23 -0700541EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800542#endif
543
Linus Torvalds1da177e2005-04-16 15:20:36 -0700544/*
545 * In order to wait for pages to become available there must be
546 * waitqueues associated with pages. By using a hash table of
547 * waitqueues where the bucket discipline is to maintain all
548 * waiters on the same queue and wake all when any of the pages
549 * become available, and for the woken contexts to check to be
550 * sure the appropriate page became available, this saves space
551 * at a cost of "thundering herd" phenomena during rare hash
552 * collisions.
553 */
554static wait_queue_head_t *page_waitqueue(struct page *page)
555{
556 const struct zone *zone = page_zone(page);
557
558 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
559}
560
561static inline void wake_up_page(struct page *page, int bit)
562{
563 __wake_up_bit(page_waitqueue(page), &page->flags, bit);
564}
565
Harvey Harrison920c7a52008-02-04 22:29:26 -0800566void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567{
568 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
569
570 if (test_bit(bit_nr, &page->flags))
Jens Axboe7eaceac2011-03-10 08:52:07 +0100571 __wait_on_bit(page_waitqueue(page), &wait, sleep_on_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 TASK_UNINTERRUPTIBLE);
573}
574EXPORT_SYMBOL(wait_on_page_bit);
575
KOSAKI Motohirof62e00c2011-05-24 17:11:29 -0700576int wait_on_page_bit_killable(struct page *page, int bit_nr)
577{
578 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
579
580 if (!test_bit(bit_nr, &page->flags))
581 return 0;
582
583 return __wait_on_bit(page_waitqueue(page), &wait,
584 sleep_on_page_killable, TASK_KILLABLE);
585}
586
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587/**
David Howells385e1ca5f2009-04-03 16:42:39 +0100588 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -0700589 * @page: Page defining the wait queue of interest
590 * @waiter: Waiter to add to the queue
David Howells385e1ca5f2009-04-03 16:42:39 +0100591 *
592 * Add an arbitrary @waiter to the wait queue for the nominated @page.
593 */
594void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
595{
596 wait_queue_head_t *q = page_waitqueue(page);
597 unsigned long flags;
598
599 spin_lock_irqsave(&q->lock, flags);
600 __add_wait_queue(q, waiter);
601 spin_unlock_irqrestore(&q->lock, flags);
602}
603EXPORT_SYMBOL_GPL(add_page_wait_queue);
604
605/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700606 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 * @page: the page
608 *
609 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
610 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
611 * mechananism between PageLocked pages and PageWriteback pages is shared.
612 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
613 *
Nick Piggin8413ac92008-10-18 20:26:59 -0700614 * The mb is necessary to enforce ordering between the clear_bit and the read
615 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800617void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618{
Nick Piggin8413ac92008-10-18 20:26:59 -0700619 VM_BUG_ON(!PageLocked(page));
620 clear_bit_unlock(PG_locked, &page->flags);
621 smp_mb__after_clear_bit();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700622 wake_up_page(page, PG_locked);
623}
624EXPORT_SYMBOL(unlock_page);
625
Randy Dunlap485bb992006-06-23 02:03:49 -0700626/**
627 * end_page_writeback - end writeback against a page
628 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629 */
630void end_page_writeback(struct page *page)
631{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700632 if (TestClearPageReclaim(page))
633 rotate_reclaimable_page(page);
634
635 if (!test_clear_page_writeback(page))
636 BUG();
637
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 smp_mb__after_clear_bit();
639 wake_up_page(page, PG_writeback);
640}
641EXPORT_SYMBOL(end_page_writeback);
642
Randy Dunlap485bb992006-06-23 02:03:49 -0700643/**
644 * __lock_page - get a lock on the page, assuming we need to sleep to get it
645 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800647void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648{
649 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
650
Jens Axboe7eaceac2011-03-10 08:52:07 +0100651 __wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 TASK_UNINTERRUPTIBLE);
653}
654EXPORT_SYMBOL(__lock_page);
655
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800656int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500657{
658 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
659
660 return __wait_on_bit_lock(page_waitqueue(page), &wait,
Jens Axboe7eaceac2011-03-10 08:52:07 +0100661 sleep_on_page_killable, TASK_KILLABLE);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500662}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300663EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500664
Michel Lespinassed065bd82010-10-26 14:21:57 -0700665int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
666 unsigned int flags)
667{
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -0700668 if (flags & FAULT_FLAG_ALLOW_RETRY) {
669 /*
670 * CAUTION! In this case, mmap_sem is not released
671 * even though return 0.
672 */
673 if (flags & FAULT_FLAG_RETRY_NOWAIT)
674 return 0;
675
676 up_read(&mm->mmap_sem);
677 if (flags & FAULT_FLAG_KILLABLE)
678 wait_on_page_locked_killable(page);
679 else
Gleb Natapov318b2752011-03-22 16:30:51 -0700680 wait_on_page_locked(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -0700681 return 0;
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -0700682 } else {
683 if (flags & FAULT_FLAG_KILLABLE) {
684 int ret;
685
686 ret = __lock_page_killable(page);
687 if (ret) {
688 up_read(&mm->mmap_sem);
689 return 0;
690 }
691 } else
692 __lock_page(page);
693 return 1;
Michel Lespinassed065bd82010-10-26 14:21:57 -0700694 }
695}
696
Randy Dunlap485bb992006-06-23 02:03:49 -0700697/**
698 * find_get_page - find and get a page reference
699 * @mapping: the address_space to search
700 * @offset: the page index
701 *
Nick Pigginda6052f2006-09-25 23:31:35 -0700702 * Is there a pagecache struct page at the given (mapping, offset) tuple?
703 * If yes, increment its refcount and return it; if no, return NULL.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 */
Nick Piggina60637c2008-07-25 19:45:31 -0700705struct page *find_get_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706{
Nick Piggina60637c2008-07-25 19:45:31 -0700707 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 struct page *page;
709
Nick Piggina60637c2008-07-25 19:45:31 -0700710 rcu_read_lock();
711repeat:
712 page = NULL;
713 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
714 if (pagep) {
715 page = radix_tree_deref_slot(pagep);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800716 if (unlikely(!page))
717 goto out;
718 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700719 goto repeat;
720
721 if (!page_cache_get_speculative(page))
722 goto repeat;
723
724 /*
725 * Has the page moved?
726 * This is part of the lockless pagecache protocol. See
727 * include/linux/pagemap.h for details.
728 */
729 if (unlikely(page != *pagep)) {
730 page_cache_release(page);
731 goto repeat;
732 }
733 }
Nick Piggin27d20fd2010-11-11 14:05:19 -0800734out:
Nick Piggina60637c2008-07-25 19:45:31 -0700735 rcu_read_unlock();
736
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 return page;
738}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739EXPORT_SYMBOL(find_get_page);
740
Randy Dunlap485bb992006-06-23 02:03:49 -0700741/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 * find_lock_page - locate, pin and lock a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700743 * @mapping: the address_space to search
744 * @offset: the page index
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 *
746 * Locates the desired pagecache page, locks it, increments its reference
747 * count and returns its address.
748 *
749 * Returns zero if the page was not present. find_lock_page() may sleep.
750 */
Nick Piggina60637c2008-07-25 19:45:31 -0700751struct page *find_lock_page(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752{
753 struct page *page;
754
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755repeat:
Nick Piggina60637c2008-07-25 19:45:31 -0700756 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 if (page) {
Nick Piggina60637c2008-07-25 19:45:31 -0700758 lock_page(page);
759 /* Has the page been truncated? */
760 if (unlikely(page->mapping != mapping)) {
761 unlock_page(page);
762 page_cache_release(page);
763 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 }
Nick Piggina60637c2008-07-25 19:45:31 -0700765 VM_BUG_ON(page->index != offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 return page;
768}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769EXPORT_SYMBOL(find_lock_page);
770
771/**
772 * find_or_create_page - locate or add a pagecache page
Martin Waitz67be2dd2005-05-01 08:59:26 -0700773 * @mapping: the page's address_space
774 * @index: the page's index into the mapping
775 * @gfp_mask: page allocation mode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 *
777 * Locates a page in the pagecache. If the page is not present, a new page
778 * is allocated using @gfp_mask and is added to the pagecache and to the VM's
779 * LRU list. The returned page is locked and has its reference count
780 * incremented.
781 *
782 * find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
783 * allocation!
784 *
785 * find_or_create_page() returns the desired page's address, or zero on
786 * memory exhaustion.
787 */
788struct page *find_or_create_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -0700789 pgoff_t index, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790{
Nick Piggineb2be182007-10-16 01:24:57 -0700791 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 int err;
793repeat:
794 page = find_lock_page(mapping, index);
795 if (!page) {
Nick Piggineb2be182007-10-16 01:24:57 -0700796 page = __page_cache_alloc(gfp_mask);
797 if (!page)
798 return NULL;
Nick Piggin67d58ac2009-01-06 14:40:28 -0800799 /*
800 * We want a regular kernel memory (not highmem or DMA etc)
801 * allocation for the radix tree nodes, but we need to honour
802 * the context-specific requirements the caller has asked for.
803 * GFP_RECLAIM_MASK collects those requirements.
804 */
805 err = add_to_page_cache_lru(page, mapping, index,
806 (gfp_mask & GFP_RECLAIM_MASK));
Nick Piggineb2be182007-10-16 01:24:57 -0700807 if (unlikely(err)) {
808 page_cache_release(page);
809 page = NULL;
810 if (err == -EEXIST)
811 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 return page;
815}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816EXPORT_SYMBOL(find_or_create_page);
817
818/**
819 * find_get_pages - gang pagecache lookup
820 * @mapping: The address_space to search
821 * @start: The starting page index
822 * @nr_pages: The maximum number of pages
823 * @pages: Where the resulting pages are placed
824 *
825 * find_get_pages() will search for and return a group of up to
826 * @nr_pages pages in the mapping. The pages are placed at @pages.
827 * find_get_pages() takes a reference against the returned pages.
828 *
829 * The search returns a group of mapping-contiguous pages with ascending
830 * indexes. There may be holes in the indices due to not-present pages.
831 *
832 * find_get_pages() returns the number of pages which were found.
833 */
834unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
835 unsigned int nr_pages, struct page **pages)
836{
837 unsigned int i;
838 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700839 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840
Nick Piggina60637c2008-07-25 19:45:31 -0700841 rcu_read_lock();
842restart:
843 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
844 (void ***)pages, start, nr_pages);
845 ret = 0;
846 for (i = 0; i < nr_found; i++) {
847 struct page *page;
848repeat:
849 page = radix_tree_deref_slot((void **)pages[i]);
850 if (unlikely(!page))
851 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700852
853 /*
854 * This can only trigger when the entry at index 0 moves out
855 * of or back to the root: none yet gotten, safe to restart.
856 */
Nick Piggin27d20fd2010-11-11 14:05:19 -0800857 if (radix_tree_deref_retry(page)) {
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700858 WARN_ON(start | i);
Nick Piggina60637c2008-07-25 19:45:31 -0700859 goto restart;
Nick Piggin27d20fd2010-11-11 14:05:19 -0800860 }
Nick Piggina60637c2008-07-25 19:45:31 -0700861
862 if (!page_cache_get_speculative(page))
863 goto repeat;
864
865 /* Has the page moved? */
866 if (unlikely(page != *((void **)pages[i]))) {
867 page_cache_release(page);
868 goto repeat;
869 }
870
871 pages[ret] = page;
872 ret++;
873 }
Hugh Dickins5b280c02011-03-22 16:33:07 -0700874
875 /*
876 * If all entries were removed before we could secure them,
877 * try again, because callers stop trying once 0 is returned.
878 */
879 if (unlikely(!ret && nr_found))
880 goto restart;
Nick Piggina60637c2008-07-25 19:45:31 -0700881 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 return ret;
883}
884
Jens Axboeebf43502006-04-27 08:46:01 +0200885/**
886 * find_get_pages_contig - gang contiguous pagecache lookup
887 * @mapping: The address_space to search
888 * @index: The starting page index
889 * @nr_pages: The maximum number of pages
890 * @pages: Where the resulting pages are placed
891 *
892 * find_get_pages_contig() works exactly like find_get_pages(), except
893 * that the returned number of pages are guaranteed to be contiguous.
894 *
895 * find_get_pages_contig() returns the number of pages which were found.
896 */
897unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
898 unsigned int nr_pages, struct page **pages)
899{
900 unsigned int i;
901 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700902 unsigned int nr_found;
Jens Axboeebf43502006-04-27 08:46:01 +0200903
Nick Piggina60637c2008-07-25 19:45:31 -0700904 rcu_read_lock();
905restart:
906 nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
907 (void ***)pages, index, nr_pages);
908 ret = 0;
909 for (i = 0; i < nr_found; i++) {
910 struct page *page;
911repeat:
912 page = radix_tree_deref_slot((void **)pages[i]);
913 if (unlikely(!page))
914 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700915
916 /*
917 * This can only trigger when the entry at index 0 moves out
918 * of or back to the root: none yet gotten, safe to restart.
919 */
Nick Piggin27d20fd2010-11-11 14:05:19 -0800920 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700921 goto restart;
922
Nick Piggina60637c2008-07-25 19:45:31 -0700923 if (!page_cache_get_speculative(page))
924 goto repeat;
925
926 /* Has the page moved? */
927 if (unlikely(page != *((void **)pages[i]))) {
928 page_cache_release(page);
929 goto repeat;
930 }
931
Nick Piggin9cbb4cb2011-01-13 15:45:51 -0800932 /*
933 * must check mapping and index after taking the ref.
934 * otherwise we can get both false positives and false
935 * negatives, which is just confusing to the caller.
936 */
937 if (page->mapping == NULL || page->index != index) {
938 page_cache_release(page);
939 break;
940 }
941
Nick Piggina60637c2008-07-25 19:45:31 -0700942 pages[ret] = page;
943 ret++;
Jens Axboeebf43502006-04-27 08:46:01 +0200944 index++;
945 }
Nick Piggina60637c2008-07-25 19:45:31 -0700946 rcu_read_unlock();
947 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +0200948}
David Howellsef71c152007-05-09 02:33:44 -0700949EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +0200950
Randy Dunlap485bb992006-06-23 02:03:49 -0700951/**
952 * find_get_pages_tag - find and return pages that match @tag
953 * @mapping: the address_space to search
954 * @index: the starting page index
955 * @tag: the tag index
956 * @nr_pages: the maximum number of pages
957 * @pages: where the resulting pages are placed
958 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -0700960 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961 */
962unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
963 int tag, unsigned int nr_pages, struct page **pages)
964{
965 unsigned int i;
966 unsigned int ret;
Nick Piggina60637c2008-07-25 19:45:31 -0700967 unsigned int nr_found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968
Nick Piggina60637c2008-07-25 19:45:31 -0700969 rcu_read_lock();
970restart:
971 nr_found = radix_tree_gang_lookup_tag_slot(&mapping->page_tree,
972 (void ***)pages, *index, nr_pages, tag);
973 ret = 0;
974 for (i = 0; i < nr_found; i++) {
975 struct page *page;
976repeat:
977 page = radix_tree_deref_slot((void **)pages[i]);
978 if (unlikely(!page))
979 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -0700980
981 /*
982 * This can only trigger when the entry at index 0 moves out
983 * of or back to the root: none yet gotten, safe to restart.
984 */
Nick Piggin27d20fd2010-11-11 14:05:19 -0800985 if (radix_tree_deref_retry(page))
Nick Piggina60637c2008-07-25 19:45:31 -0700986 goto restart;
987
988 if (!page_cache_get_speculative(page))
989 goto repeat;
990
991 /* Has the page moved? */
992 if (unlikely(page != *((void **)pages[i]))) {
993 page_cache_release(page);
994 goto repeat;
995 }
996
997 pages[ret] = page;
998 ret++;
999 }
Hugh Dickins5b280c02011-03-22 16:33:07 -07001000
1001 /*
1002 * If all entries were removed before we could secure them,
1003 * try again, because callers stop trying once 0 is returned.
1004 */
1005 if (unlikely(!ret && nr_found))
1006 goto restart;
Nick Piggina60637c2008-07-25 19:45:31 -07001007 rcu_read_unlock();
1008
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009 if (ret)
1010 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -07001011
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012 return ret;
1013}
David Howellsef71c152007-05-09 02:33:44 -07001014EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001015
Randy Dunlap485bb992006-06-23 02:03:49 -07001016/**
1017 * grab_cache_page_nowait - returns locked page at given index in given cache
1018 * @mapping: target address_space
1019 * @index: the page index
1020 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -08001021 * Same as grab_cache_page(), but do not wait if the page is unavailable.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 * This is intended for speculative data generators, where the data can
1023 * be regenerated if the page couldn't be grabbed. This routine should
1024 * be safe to call while holding the lock for another page.
1025 *
1026 * Clear __GFP_FS when allocating the page to avoid recursion into the fs
1027 * and deadlock against the caller's locked page.
1028 */
1029struct page *
Fengguang Wu57f6b962007-10-16 01:24:37 -07001030grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001031{
1032 struct page *page = find_get_page(mapping, index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033
1034 if (page) {
Nick Piggin529ae9a2008-08-02 12:01:03 +02001035 if (trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036 return page;
1037 page_cache_release(page);
1038 return NULL;
1039 }
Nick Piggin2ae88142006-10-28 10:38:23 -07001040 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
Nick Piggin67d58ac2009-01-06 14:40:28 -08001041 if (page && add_to_page_cache_lru(page, mapping, index, GFP_NOFS)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 page_cache_release(page);
1043 page = NULL;
1044 }
1045 return page;
1046}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047EXPORT_SYMBOL(grab_cache_page_nowait);
1048
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001049/*
1050 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
1051 * a _large_ part of the i/o request. Imagine the worst scenario:
1052 *
1053 * ---R__________________________________________B__________
1054 * ^ reading here ^ bad block(assume 4k)
1055 *
1056 * read(R) => miss => readahead(R...B) => media error => frustrating retries
1057 * => failing the whole request => read(R) => read(R+1) =>
1058 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
1059 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
1060 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
1061 *
1062 * It is going insane. Fix it by quickly scaling down the readahead size.
1063 */
1064static void shrink_readahead_size_eio(struct file *filp,
1065 struct file_ra_state *ra)
1066{
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001067 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001068}
1069
Randy Dunlap485bb992006-06-23 02:03:49 -07001070/**
Christoph Hellwig36e78912008-02-08 04:21:24 -08001071 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001072 * @filp: the file to read
1073 * @ppos: current file position
1074 * @desc: read_descriptor
1075 * @actor: read method
1076 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -07001078 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 *
1080 * This is really ugly. But the goto's actually try to clarify some
1081 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082 */
Christoph Hellwig36e78912008-02-08 04:21:24 -08001083static void do_generic_file_read(struct file *filp, loff_t *ppos,
1084 read_descriptor_t *desc, read_actor_t actor)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085{
Christoph Hellwig36e78912008-02-08 04:21:24 -08001086 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001087 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -08001088 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001089 pgoff_t index;
1090 pgoff_t last_index;
1091 pgoff_t prev_index;
1092 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -07001093 unsigned int prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -07001097 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
1098 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
1100 offset = *ppos & ~PAGE_CACHE_MASK;
1101
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 for (;;) {
1103 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001104 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -07001105 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001106 unsigned long nr, ret;
1107
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001109find_page:
1110 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001111 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001112 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001113 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001114 index, last_index - index);
1115 page = find_get_page(mapping, index);
1116 if (unlikely(page == NULL))
1117 goto no_cached_page;
1118 }
1119 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001120 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001121 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001122 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001124 if (!PageUptodate(page)) {
1125 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1126 !mapping->a_ops->is_partially_uptodate)
1127 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001128 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001129 goto page_not_up_to_date;
Dave Hansen8d056cb2010-11-11 14:05:15 -08001130 /* Did it get truncated before we got the lock? */
1131 if (!page->mapping)
1132 goto page_not_up_to_date_locked;
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001133 if (!mapping->a_ops->is_partially_uptodate(page,
1134 desc, offset))
1135 goto page_not_up_to_date_locked;
1136 unlock_page(page);
1137 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001139 /*
1140 * i_size must be checked after we know the page is Uptodate.
1141 *
1142 * Checking i_size after the check allows us to calculate
1143 * the correct value for "nr", which means the zero-filled
1144 * part of the page is not copied back to userspace (unless
1145 * another truncate extends the file - this is desired though).
1146 */
1147
1148 isize = i_size_read(inode);
1149 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1150 if (unlikely(!isize || index > end_index)) {
1151 page_cache_release(page);
1152 goto out;
1153 }
1154
1155 /* nr is the maximum number of bytes to copy from this page */
1156 nr = PAGE_CACHE_SIZE;
1157 if (index == end_index) {
1158 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1159 if (nr <= offset) {
1160 page_cache_release(page);
1161 goto out;
1162 }
1163 }
1164 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165
1166 /* If users can be writing to this page using arbitrary
1167 * virtual addresses, take care about potential aliasing
1168 * before reading the page on the kernel side.
1169 */
1170 if (mapping_writably_mapped(mapping))
1171 flush_dcache_page(page);
1172
1173 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001174 * When a sequential read accesses a page several times,
1175 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176 */
Jan Karaec0f1632007-05-06 14:49:25 -07001177 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001178 mark_page_accessed(page);
1179 prev_index = index;
1180
1181 /*
1182 * Ok, we have the page, and it's up-to-date, so
1183 * now we can copy it to user space...
1184 *
1185 * The actor routine returns how many bytes were actually used..
1186 * NOTE! This may not be the same as how much of a user buffer
1187 * we filled up (we may be padding etc), so we can only update
1188 * "pos" here (the actor routine has to update the user buffer
1189 * pointers and the remaining count).
1190 */
1191 ret = actor(desc, page, offset, nr);
1192 offset += ret;
1193 index += offset >> PAGE_CACHE_SHIFT;
1194 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001195 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196
1197 page_cache_release(page);
1198 if (ret == nr && desc->count)
1199 continue;
1200 goto out;
1201
1202page_not_up_to_date:
1203 /* Get exclusive access to the page ... */
Oleg Nesterov85462322008-06-08 21:20:43 +04001204 error = lock_page_killable(page);
1205 if (unlikely(error))
1206 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001208page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001209 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001210 if (!page->mapping) {
1211 unlock_page(page);
1212 page_cache_release(page);
1213 continue;
1214 }
1215
1216 /* Did somebody else fill it already? */
1217 if (PageUptodate(page)) {
1218 unlock_page(page);
1219 goto page_ok;
1220 }
1221
1222readpage:
Jeff Moyer91803b42010-05-26 11:49:40 -04001223 /*
1224 * A previous I/O error may have been due to temporary
1225 * failures, eg. multipath errors.
1226 * PG_error will be set again if readpage fails.
1227 */
1228 ClearPageError(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 /* Start the actual read. The read will unlock the page. */
1230 error = mapping->a_ops->readpage(filp, page);
1231
Zach Brown994fc28c2005-12-15 14:28:17 -08001232 if (unlikely(error)) {
1233 if (error == AOP_TRUNCATED_PAGE) {
1234 page_cache_release(page);
1235 goto find_page;
1236 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001238 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239
1240 if (!PageUptodate(page)) {
Oleg Nesterov85462322008-06-08 21:20:43 +04001241 error = lock_page_killable(page);
1242 if (unlikely(error))
1243 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244 if (!PageUptodate(page)) {
1245 if (page->mapping == NULL) {
1246 /*
Christoph Hellwig2ecdc822010-01-26 17:27:20 +01001247 * invalidate_mapping_pages got it
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 */
1249 unlock_page(page);
1250 page_cache_release(page);
1251 goto find_page;
1252 }
1253 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001254 shrink_readahead_size_eio(filp, ra);
Oleg Nesterov85462322008-06-08 21:20:43 +04001255 error = -EIO;
1256 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 }
1258 unlock_page(page);
1259 }
1260
Linus Torvalds1da177e2005-04-16 15:20:36 -07001261 goto page_ok;
1262
1263readpage_error:
1264 /* UHHUH! A synchronous read error occurred. Report it */
1265 desc->error = error;
1266 page_cache_release(page);
1267 goto out;
1268
1269no_cached_page:
1270 /*
1271 * Ok, it wasn't cached, so we need to create a new
1272 * page..
1273 */
Nick Piggineb2be182007-10-16 01:24:57 -07001274 page = page_cache_alloc_cold(mapping);
1275 if (!page) {
1276 desc->error = -ENOMEM;
1277 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 }
Nick Piggineb2be182007-10-16 01:24:57 -07001279 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280 index, GFP_KERNEL);
1281 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001282 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001283 if (error == -EEXIST)
1284 goto find_page;
1285 desc->error = error;
1286 goto out;
1287 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001288 goto readpage;
1289 }
1290
1291out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001292 ra->prev_pos = prev_index;
1293 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1294 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001296 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Krishna Kumar0c6aa262008-10-15 22:01:13 -07001297 file_accessed(filp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001298}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299
1300int file_read_actor(read_descriptor_t *desc, struct page *page,
1301 unsigned long offset, unsigned long size)
1302{
1303 char *kaddr;
1304 unsigned long left, count = desc->count;
1305
1306 if (size > count)
1307 size = count;
1308
1309 /*
1310 * Faults on the destination of a read are common, so do it before
1311 * taking the kmap.
1312 */
1313 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
1314 kaddr = kmap_atomic(page, KM_USER0);
1315 left = __copy_to_user_inatomic(desc->arg.buf,
1316 kaddr + offset, size);
1317 kunmap_atomic(kaddr, KM_USER0);
1318 if (left == 0)
1319 goto success;
1320 }
1321
1322 /* Do it the slow way */
1323 kaddr = kmap(page);
1324 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
1325 kunmap(page);
1326
1327 if (left) {
1328 size -= left;
1329 desc->error = -EFAULT;
1330 }
1331success:
1332 desc->count = count - size;
1333 desc->written += size;
1334 desc->arg.buf += size;
1335 return size;
1336}
1337
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001338/*
1339 * Performs necessary checks before doing a write
1340 * @iov: io vector request
1341 * @nr_segs: number of segments in the iovec
1342 * @count: number of bytes to write
1343 * @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
1344 *
1345 * Adjust number of segments and amount of bytes to write (nr_segs should be
1346 * properly initialized first). Returns appropriate error code that caller
1347 * should return or zero in case that write should be allowed.
1348 */
1349int generic_segment_checks(const struct iovec *iov,
1350 unsigned long *nr_segs, size_t *count, int access_flags)
1351{
1352 unsigned long seg;
1353 size_t cnt = 0;
1354 for (seg = 0; seg < *nr_segs; seg++) {
1355 const struct iovec *iv = &iov[seg];
1356
1357 /*
1358 * If any segment has a negative length, or the cumulative
1359 * length ever wraps negative then return -EINVAL.
1360 */
1361 cnt += iv->iov_len;
1362 if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
1363 return -EINVAL;
1364 if (access_ok(access_flags, iv->iov_base, iv->iov_len))
1365 continue;
1366 if (seg == 0)
1367 return -EFAULT;
1368 *nr_segs = seg;
1369 cnt -= iv->iov_len; /* This segment is no good */
1370 break;
1371 }
1372 *count = cnt;
1373 return 0;
1374}
1375EXPORT_SYMBOL(generic_segment_checks);
1376
Randy Dunlap485bb992006-06-23 02:03:49 -07001377/**
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001378 * generic_file_aio_read - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001379 * @iocb: kernel I/O control block
1380 * @iov: io vector request
1381 * @nr_segs: number of segments in the iovec
Henrik Kretzschmarb2abacf2006-10-04 02:15:22 -07001382 * @pos: current file position
Randy Dunlap485bb992006-06-23 02:03:49 -07001383 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 * This is the "read()" routine for all filesystems
1385 * that can use the page cache directly.
1386 */
1387ssize_t
Badari Pulavarty543ade12006-09-30 23:28:48 -07001388generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
1389 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390{
1391 struct file *filp = iocb->ki_filp;
1392 ssize_t retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001393 unsigned long seg = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 size_t count;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001395 loff_t *ppos = &iocb->ki_pos;
Jens Axboe55602dd2010-06-24 15:05:37 +02001396 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397
1398 count = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07001399 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1400 if (retval)
1401 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402
Jens Axboe55602dd2010-06-24 15:05:37 +02001403 blk_start_plug(&plug);
1404
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
1406 if (filp->f_flags & O_DIRECT) {
Badari Pulavarty543ade12006-09-30 23:28:48 -07001407 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408 struct address_space *mapping;
1409 struct inode *inode;
1410
1411 mapping = filp->f_mapping;
1412 inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 if (!count)
1414 goto out; /* skip atime */
1415 size = i_size_read(inode);
1416 if (pos < size) {
Nick Piggin48b47c52009-01-06 14:40:22 -08001417 retval = filemap_write_and_wait_range(mapping, pos,
1418 pos + iov_length(iov, nr_segs) - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07001419 if (!retval) {
1420 retval = mapping->a_ops->direct_IO(READ, iocb,
1421 iov, pos, nr_segs);
1422 }
Josef Bacik66f998f2010-05-23 11:00:54 -04001423 if (retval > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 *ppos = pos + retval;
Josef Bacik66f998f2010-05-23 11:00:54 -04001425 count -= retval;
1426 }
1427
1428 /*
1429 * Btrfs can have a short DIO read if we encounter
1430 * compressed extents, so if there was an error, or if
1431 * we've already read everything we wanted to, or if
1432 * there was a short read because we hit EOF, go ahead
1433 * and return. Otherwise fallthrough to buffered io for
1434 * the rest of the read.
1435 */
1436 if (retval < 0 || !count || *ppos >= size) {
Hugh Dickins11fa9772008-07-23 21:27:34 -07001437 file_accessed(filp);
1438 goto out;
1439 }
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001440 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441 }
1442
Josef Bacik66f998f2010-05-23 11:00:54 -04001443 count = retval;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001444 for (seg = 0; seg < nr_segs; seg++) {
1445 read_descriptor_t desc;
Josef Bacik66f998f2010-05-23 11:00:54 -04001446 loff_t offset = 0;
1447
1448 /*
1449 * If we did a short DIO read we need to skip the section of the
1450 * iov that we've already read data into.
1451 */
1452 if (count) {
1453 if (count > iov[seg].iov_len) {
1454 count -= iov[seg].iov_len;
1455 continue;
1456 }
1457 offset = count;
1458 count = 0;
1459 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460
Hugh Dickins11fa9772008-07-23 21:27:34 -07001461 desc.written = 0;
Josef Bacik66f998f2010-05-23 11:00:54 -04001462 desc.arg.buf = iov[seg].iov_base + offset;
1463 desc.count = iov[seg].iov_len - offset;
Hugh Dickins11fa9772008-07-23 21:27:34 -07001464 if (desc.count == 0)
1465 continue;
1466 desc.error = 0;
1467 do_generic_file_read(filp, ppos, &desc, file_read_actor);
1468 retval += desc.written;
1469 if (desc.error) {
1470 retval = retval ?: desc.error;
1471 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 }
Hugh Dickins11fa9772008-07-23 21:27:34 -07001473 if (desc.count > 0)
1474 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 }
1476out:
Jens Axboe55602dd2010-06-24 15:05:37 +02001477 blk_finish_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001478 return retval;
1479}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480EXPORT_SYMBOL(generic_file_aio_read);
1481
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482static ssize_t
1483do_readahead(struct address_space *mapping, struct file *filp,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001484 pgoff_t index, unsigned long nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485{
1486 if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
1487 return -EINVAL;
1488
Wu Fengguangf7e839d2009-06-16 15:31:20 -07001489 force_page_cache_readahead(mapping, filp, index, nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 return 0;
1491}
1492
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001493SYSCALL_DEFINE(readahead)(int fd, loff_t offset, size_t count)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494{
1495 ssize_t ret;
1496 struct file *file;
1497
1498 ret = -EBADF;
1499 file = fget(fd);
1500 if (file) {
1501 if (file->f_mode & FMODE_READ) {
1502 struct address_space *mapping = file->f_mapping;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001503 pgoff_t start = offset >> PAGE_CACHE_SHIFT;
1504 pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 unsigned long len = end - start + 1;
1506 ret = do_readahead(mapping, file, start, len);
1507 }
1508 fput(file);
1509 }
1510 return ret;
1511}
Heiko Carstens6673e0c2009-01-14 14:14:02 +01001512#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
1513asmlinkage long SyS_readahead(long fd, loff_t offset, long count)
1514{
1515 return SYSC_readahead((int) fd, offset, (size_t) count);
1516}
1517SYSCALL_ALIAS(sys_readahead, SyS_readahead);
1518#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519
1520#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001521/**
1522 * page_cache_read - adds requested page to the page cache if not already there
1523 * @file: file to read
1524 * @offset: page index
1525 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 * This adds the requested page to the page cache if it isn't already there,
1527 * and schedules an I/O to read in its contents from disk.
1528 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001529static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530{
1531 struct address_space *mapping = file->f_mapping;
1532 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001533 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534
Zach Brown994fc28c2005-12-15 14:28:17 -08001535 do {
1536 page = page_cache_alloc_cold(mapping);
1537 if (!page)
1538 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539
Zach Brown994fc28c2005-12-15 14:28:17 -08001540 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1541 if (ret == 0)
1542 ret = mapping->a_ops->readpage(file, page);
1543 else if (ret == -EEXIST)
1544 ret = 0; /* losing race to add is OK */
1545
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547
Zach Brown994fc28c2005-12-15 14:28:17 -08001548 } while (ret == AOP_TRUNCATED_PAGE);
1549
1550 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001551}
1552
1553#define MMAP_LOTSAMISS (100)
1554
Linus Torvaldsef00e082009-06-16 15:31:25 -07001555/*
1556 * Synchronous readahead happens when we don't even find
1557 * a page in the page cache at all.
1558 */
1559static void do_sync_mmap_readahead(struct vm_area_struct *vma,
1560 struct file_ra_state *ra,
1561 struct file *file,
1562 pgoff_t offset)
1563{
1564 unsigned long ra_pages;
1565 struct address_space *mapping = file->f_mapping;
1566
1567 /* If we don't want any read-ahead, don't bother */
1568 if (VM_RandomReadHint(vma))
1569 return;
Wu Fengguang275b12b2011-05-24 17:12:28 -07001570 if (!ra->ra_pages)
1571 return;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001572
Wu Fengguang2cbea1d2011-05-24 17:12:30 -07001573 if (VM_SequentialReadHint(vma)) {
Wu Fengguang7ffc59b2009-06-16 15:31:38 -07001574 page_cache_sync_readahead(mapping, ra, file, offset,
1575 ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001576 return;
1577 }
1578
Andi Kleen207d04b2011-05-24 17:12:29 -07001579 /* Avoid banging the cache line if not needed */
1580 if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
Linus Torvaldsef00e082009-06-16 15:31:25 -07001581 ra->mmap_miss++;
1582
1583 /*
1584 * Do we miss much more than hit in this file? If so,
1585 * stop bothering with read-ahead. It will only hurt.
1586 */
1587 if (ra->mmap_miss > MMAP_LOTSAMISS)
1588 return;
1589
Wu Fengguangd30a1102009-06-16 15:31:30 -07001590 /*
1591 * mmap read-around
1592 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001593 ra_pages = max_sane_readahead(ra->ra_pages);
Wu Fengguang275b12b2011-05-24 17:12:28 -07001594 ra->start = max_t(long, 0, offset - ra_pages / 2);
1595 ra->size = ra_pages;
Wu Fengguang2cbea1d2011-05-24 17:12:30 -07001596 ra->async_size = ra_pages / 4;
Wu Fengguang275b12b2011-05-24 17:12:28 -07001597 ra_submit(ra, mapping, file);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001598}
1599
1600/*
1601 * Asynchronous readahead happens when we find the page and PG_readahead,
1602 * so we want to possibly extend the readahead further..
1603 */
1604static void do_async_mmap_readahead(struct vm_area_struct *vma,
1605 struct file_ra_state *ra,
1606 struct file *file,
1607 struct page *page,
1608 pgoff_t offset)
1609{
1610 struct address_space *mapping = file->f_mapping;
1611
1612 /* If we don't want any read-ahead, don't bother */
1613 if (VM_RandomReadHint(vma))
1614 return;
1615 if (ra->mmap_miss > 0)
1616 ra->mmap_miss--;
1617 if (PageReadahead(page))
Wu Fengguang2fad6f52009-06-16 15:31:29 -07001618 page_cache_async_readahead(mapping, ra, file,
1619 page, offset, ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001620}
1621
Randy Dunlap485bb992006-06-23 02:03:49 -07001622/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001623 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001624 * @vma: vma in which the fault was taken
1625 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001626 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001627 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001628 * mapped memory region to read in file data during a page fault.
1629 *
1630 * The goto's are kind of ugly, but this streamlines the normal case of having
1631 * it in the page cache, and handles the special cases reasonably without
1632 * having a lot of duplicated code.
1633 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001634int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635{
1636 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001637 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 struct address_space *mapping = file->f_mapping;
1639 struct file_ra_state *ra = &file->f_ra;
1640 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001641 pgoff_t offset = vmf->pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 struct page *page;
Jan Kara2004dc82008-02-08 04:20:11 -08001643 pgoff_t size;
Nick Piggin83c54072007-07-19 01:47:05 -07001644 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001647 if (offset >= size)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001648 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001649
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651 * Do we have something in the page cache already?
1652 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001653 page = find_get_page(mapping, offset);
1654 if (likely(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07001656 * We found the page, so try async readahead before
1657 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001658 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001659 do_async_mmap_readahead(vma, ra, file, page, offset);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001660 } else {
1661 /* No page in the page cache at all */
1662 do_sync_mmap_readahead(vma, ra, file, offset);
1663 count_vm_event(PGMAJFAULT);
Ying Han456f9982011-05-26 16:25:38 -07001664 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001665 ret = VM_FAULT_MAJOR;
1666retry_find:
Michel Lespinasseb522c942010-10-26 14:21:56 -07001667 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001668 if (!page)
1669 goto no_cached_page;
1670 }
1671
Michel Lespinassed88c0922010-11-02 13:05:18 -07001672 if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
1673 page_cache_release(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -07001674 return ret | VM_FAULT_RETRY;
Michel Lespinassed88c0922010-11-02 13:05:18 -07001675 }
Michel Lespinasseb522c942010-10-26 14:21:56 -07001676
1677 /* Did it get truncated? */
1678 if (unlikely(page->mapping != mapping)) {
1679 unlock_page(page);
1680 put_page(page);
1681 goto retry_find;
1682 }
1683 VM_BUG_ON(page->index != offset);
1684
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001686 * We have a locked page in the page cache, now we need to check
1687 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688 */
Nick Piggind00806b2007-07-19 01:46:57 -07001689 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 goto page_not_uptodate;
1691
Linus Torvaldsef00e082009-06-16 15:31:25 -07001692 /*
1693 * Found the page and have a reference on it.
1694 * We must recheck i_size under page lock.
1695 */
Nick Piggind00806b2007-07-19 01:46:57 -07001696 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001697 if (unlikely(offset >= size)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001698 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001699 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001700 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001701 }
1702
Nick Piggind0217ac2007-07-19 01:47:03 -07001703 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001704 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001705
Linus Torvalds1da177e2005-04-16 15:20:36 -07001706no_cached_page:
1707 /*
1708 * We're only likely to ever get here if MADV_RANDOM is in
1709 * effect.
1710 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001711 error = page_cache_read(file, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712
1713 /*
1714 * The page we want has now been added to the page cache.
1715 * In the unlikely event that someone removed it in the
1716 * meantime, we'll just come back here and read it again.
1717 */
1718 if (error >= 0)
1719 goto retry_find;
1720
1721 /*
1722 * An error return from page_cache_read can result if the
1723 * system is low on memory, or a problem occurs while trying
1724 * to schedule I/O.
1725 */
1726 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001727 return VM_FAULT_OOM;
1728 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729
1730page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 /*
1732 * Umm, take care of errors if the page isn't up-to-date.
1733 * Try to re-read it _once_. We do this synchronously,
1734 * because there really aren't any performance issues here
1735 * and we need to check for errors.
1736 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001738 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001739 if (!error) {
1740 wait_on_page_locked(page);
1741 if (!PageUptodate(page))
1742 error = -EIO;
1743 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001745
1746 if (!error || error == AOP_TRUNCATED_PAGE)
1747 goto retry_find;
1748
1749 /* Things didn't work out. Return zero to tell the mm layer so. */
1750 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001751 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001752}
1753EXPORT_SYMBOL(filemap_fault);
1754
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04001755const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07001756 .fault = filemap_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757};
1758
1759/* This is used for a general mmap of a disk file */
1760
1761int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1762{
1763 struct address_space *mapping = file->f_mapping;
1764
1765 if (!mapping->a_ops->readpage)
1766 return -ENOEXEC;
1767 file_accessed(file);
1768 vma->vm_ops = &generic_file_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001769 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 return 0;
1771}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772
1773/*
1774 * This is for filesystems which do not implement ->writepage.
1775 */
1776int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
1777{
1778 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
1779 return -EINVAL;
1780 return generic_file_mmap(file, vma);
1781}
1782#else
1783int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
1784{
1785 return -ENOSYS;
1786}
1787int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
1788{
1789 return -ENOSYS;
1790}
1791#endif /* CONFIG_MMU */
1792
1793EXPORT_SYMBOL(generic_file_mmap);
1794EXPORT_SYMBOL(generic_file_readonly_mmap);
1795
Nick Piggin6fe69002007-05-06 14:49:04 -07001796static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001797 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001799 void *data,
1800 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801{
Nick Piggineb2be182007-10-16 01:24:57 -07001802 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001803 int err;
1804repeat:
1805 page = find_get_page(mapping, index);
1806 if (!page) {
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001807 page = __page_cache_alloc(gfp | __GFP_COLD);
Nick Piggineb2be182007-10-16 01:24:57 -07001808 if (!page)
1809 return ERR_PTR(-ENOMEM);
1810 err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
1811 if (unlikely(err)) {
1812 page_cache_release(page);
1813 if (err == -EEXIST)
1814 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 return ERR_PTR(err);
1817 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001818 err = filler(data, page);
1819 if (err < 0) {
1820 page_cache_release(page);
1821 page = ERR_PTR(err);
1822 }
1823 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001824 return page;
1825}
1826
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001827static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001828 pgoff_t index,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829 int (*filler)(void *,struct page*),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001830 void *data,
1831 gfp_t gfp)
1832
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833{
1834 struct page *page;
1835 int err;
1836
1837retry:
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001838 page = __read_cache_page(mapping, index, filler, data, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01001840 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 if (PageUptodate(page))
1842 goto out;
1843
1844 lock_page(page);
1845 if (!page->mapping) {
1846 unlock_page(page);
1847 page_cache_release(page);
1848 goto retry;
1849 }
1850 if (PageUptodate(page)) {
1851 unlock_page(page);
1852 goto out;
1853 }
1854 err = filler(data, page);
1855 if (err < 0) {
1856 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01001857 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858 }
David Howellsc855ff32007-05-09 13:42:20 +01001859out:
Nick Piggin6fe69002007-05-06 14:49:04 -07001860 mark_page_accessed(page);
1861 return page;
1862}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001863
1864/**
1865 * read_cache_page_async - read into page cache, fill it if needed
1866 * @mapping: the page's address_space
1867 * @index: the page index
1868 * @filler: function to perform the read
1869 * @data: destination for read data
1870 *
1871 * Same as read_cache_page, but don't wait for page to become unlocked
1872 * after submitting it to the filler.
1873 *
1874 * Read into the page cache. If a page already exists, and PageUptodate() is
1875 * not set, try to fill the page but don't wait for it to become unlocked.
1876 *
1877 * If the page does not get brought uptodate, return -EIO.
1878 */
1879struct page *read_cache_page_async(struct address_space *mapping,
1880 pgoff_t index,
1881 int (*filler)(void *,struct page*),
1882 void *data)
1883{
1884 return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
1885}
Nick Piggin6fe69002007-05-06 14:49:04 -07001886EXPORT_SYMBOL(read_cache_page_async);
1887
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001888static struct page *wait_on_page_read(struct page *page)
1889{
1890 if (!IS_ERR(page)) {
1891 wait_on_page_locked(page);
1892 if (!PageUptodate(page)) {
1893 page_cache_release(page);
1894 page = ERR_PTR(-EIO);
1895 }
1896 }
1897 return page;
1898}
1899
1900/**
1901 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
1902 * @mapping: the page's address_space
1903 * @index: the page index
1904 * @gfp: the page allocator flags to use if allocating
1905 *
1906 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
1907 * any new page allocations done using the specified allocation flags. Note
1908 * that the Radix tree operations will still use GFP_KERNEL, so you can't
1909 * expect to do this atomically or anything like that - but you can pass in
1910 * other page requirements.
1911 *
1912 * If the page does not get brought uptodate, return -EIO.
1913 */
1914struct page *read_cache_page_gfp(struct address_space *mapping,
1915 pgoff_t index,
1916 gfp_t gfp)
1917{
1918 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
1919
1920 return wait_on_page_read(do_read_cache_page(mapping, index, filler, NULL, gfp));
1921}
1922EXPORT_SYMBOL(read_cache_page_gfp);
1923
Nick Piggin6fe69002007-05-06 14:49:04 -07001924/**
1925 * read_cache_page - read into page cache, fill it if needed
1926 * @mapping: the page's address_space
1927 * @index: the page index
1928 * @filler: function to perform the read
1929 * @data: destination for read data
1930 *
1931 * Read into the page cache. If a page already exists, and PageUptodate() is
1932 * not set, try to fill the page then wait for it to become unlocked.
1933 *
1934 * If the page does not get brought uptodate, return -EIO.
1935 */
1936struct page *read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07001937 pgoff_t index,
Nick Piggin6fe69002007-05-06 14:49:04 -07001938 int (*filler)(void *,struct page*),
1939 void *data)
1940{
Linus Torvalds0531b2a2010-01-27 09:20:03 -08001941 return wait_on_page_read(read_cache_page_async(mapping, index, filler, data));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943EXPORT_SYMBOL(read_cache_page);
1944
1945/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946 * The logic we want is
1947 *
1948 * if suid or (sgid and xgrp)
1949 * remove privs
1950 */
Jens Axboe01de85e2006-10-17 19:50:36 +02001951int should_remove_suid(struct dentry *dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952{
1953 mode_t mode = dentry->d_inode->i_mode;
1954 int kill = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955
1956 /* suid always must be killed */
1957 if (unlikely(mode & S_ISUID))
1958 kill = ATTR_KILL_SUID;
1959
1960 /*
1961 * sgid without any exec bits is just a mandatory locking mark; leave
1962 * it alone. If some exec bits are set, it's a real sgid; kill it.
1963 */
1964 if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
1965 kill |= ATTR_KILL_SGID;
1966
Dmitri Monakhov7f5ff762008-12-01 14:34:56 -08001967 if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode)))
Jens Axboe01de85e2006-10-17 19:50:36 +02001968 return kill;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969
Jens Axboe01de85e2006-10-17 19:50:36 +02001970 return 0;
1971}
Mark Fashehd23a1472006-10-17 17:05:18 -07001972EXPORT_SYMBOL(should_remove_suid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001973
Miklos Szeredi7f3d4ee2008-05-07 09:22:39 +02001974static int __remove_suid(struct dentry *dentry, int kill)
Jens Axboe01de85e2006-10-17 19:50:36 +02001975{
1976 struct iattr newattrs;
1977
1978 newattrs.ia_valid = ATTR_FORCE | kill;
1979 return notify_change(dentry, &newattrs);
1980}
1981
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001982int file_remove_suid(struct file *file)
Jens Axboe01de85e2006-10-17 19:50:36 +02001983{
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001984 struct dentry *dentry = file->f_path.dentry;
Serge E. Hallynb5376772007-10-16 23:31:36 -07001985 int killsuid = should_remove_suid(dentry);
1986 int killpriv = security_inode_need_killpriv(dentry);
1987 int error = 0;
Jens Axboe01de85e2006-10-17 19:50:36 +02001988
Serge E. Hallynb5376772007-10-16 23:31:36 -07001989 if (killpriv < 0)
1990 return killpriv;
1991 if (killpriv)
1992 error = security_inode_killpriv(dentry);
1993 if (!error && killsuid)
1994 error = __remove_suid(dentry, killsuid);
Jens Axboe01de85e2006-10-17 19:50:36 +02001995
Serge E. Hallynb5376772007-10-16 23:31:36 -07001996 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997}
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02001998EXPORT_SYMBOL(file_remove_suid);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001999
Nick Piggin2f718ff2007-10-16 01:24:59 -07002000static size_t __iovec_copy_from_user_inatomic(char *vaddr,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001 const struct iovec *iov, size_t base, size_t bytes)
2002{
Ingo Molnarf1800532009-03-02 11:00:57 +01002003 size_t copied = 0, left = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002004
2005 while (bytes) {
2006 char __user *buf = iov->iov_base + base;
2007 int copy = min(bytes, iov->iov_len - base);
2008
2009 base = 0;
Ingo Molnarf1800532009-03-02 11:00:57 +01002010 left = __copy_from_user_inatomic(vaddr, buf, copy);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002011 copied += copy;
2012 bytes -= copy;
2013 vaddr += copy;
2014 iov++;
2015
NeilBrown01408c42006-06-25 05:47:58 -07002016 if (unlikely(left))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002018 }
2019 return copied - left;
2020}
2021
2022/*
Nick Piggin2f718ff2007-10-16 01:24:59 -07002023 * Copy as much as we can into the page and return the number of bytes which
André Goddard Rosaaf901ca2009-11-14 13:09:05 -02002024 * were successfully copied. If a fault is encountered then return the number of
Nick Piggin2f718ff2007-10-16 01:24:59 -07002025 * bytes which were copied.
2026 */
2027size_t iov_iter_copy_from_user_atomic(struct page *page,
2028 struct iov_iter *i, unsigned long offset, size_t bytes)
2029{
2030 char *kaddr;
2031 size_t copied;
2032
2033 BUG_ON(!in_atomic());
2034 kaddr = kmap_atomic(page, KM_USER0);
2035 if (likely(i->nr_segs == 1)) {
2036 int left;
2037 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01002038 left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002039 copied = bytes - left;
2040 } else {
2041 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
2042 i->iov, i->iov_offset, bytes);
2043 }
2044 kunmap_atomic(kaddr, KM_USER0);
2045
2046 return copied;
2047}
Nick Piggin89e10782007-10-16 01:25:07 -07002048EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002049
2050/*
2051 * This has the same sideeffects and return value as
2052 * iov_iter_copy_from_user_atomic().
2053 * The difference is that it attempts to resolve faults.
2054 * Page must not be locked.
2055 */
2056size_t iov_iter_copy_from_user(struct page *page,
2057 struct iov_iter *i, unsigned long offset, size_t bytes)
2058{
2059 char *kaddr;
2060 size_t copied;
2061
2062 kaddr = kmap(page);
2063 if (likely(i->nr_segs == 1)) {
2064 int left;
2065 char __user *buf = i->iov->iov_base + i->iov_offset;
Ingo Molnarf1800532009-03-02 11:00:57 +01002066 left = __copy_from_user(kaddr + offset, buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002067 copied = bytes - left;
2068 } else {
2069 copied = __iovec_copy_from_user_inatomic(kaddr + offset,
2070 i->iov, i->iov_offset, bytes);
2071 }
2072 kunmap(page);
2073 return copied;
2074}
Nick Piggin89e10782007-10-16 01:25:07 -07002075EXPORT_SYMBOL(iov_iter_copy_from_user);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002076
Nick Pigginf7009262008-03-10 11:43:59 -07002077void iov_iter_advance(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07002078{
Nick Pigginf7009262008-03-10 11:43:59 -07002079 BUG_ON(i->count < bytes);
2080
Nick Piggin2f718ff2007-10-16 01:24:59 -07002081 if (likely(i->nr_segs == 1)) {
2082 i->iov_offset += bytes;
Nick Pigginf7009262008-03-10 11:43:59 -07002083 i->count -= bytes;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002084 } else {
2085 const struct iovec *iov = i->iov;
2086 size_t base = i->iov_offset;
2087
Nick Piggin124d3b72008-02-02 15:01:17 +01002088 /*
2089 * The !iov->iov_len check ensures we skip over unlikely
Nick Pigginf7009262008-03-10 11:43:59 -07002090 * zero-length segments (without overruning the iovec).
Nick Piggin124d3b72008-02-02 15:01:17 +01002091 */
Linus Torvalds94ad3742008-07-30 14:45:12 -07002092 while (bytes || unlikely(i->count && !iov->iov_len)) {
Nick Pigginf7009262008-03-10 11:43:59 -07002093 int copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002094
Nick Pigginf7009262008-03-10 11:43:59 -07002095 copy = min(bytes, iov->iov_len - base);
2096 BUG_ON(!i->count || i->count < copy);
2097 i->count -= copy;
Nick Piggin2f718ff2007-10-16 01:24:59 -07002098 bytes -= copy;
2099 base += copy;
2100 if (iov->iov_len == base) {
2101 iov++;
2102 base = 0;
2103 }
2104 }
2105 i->iov = iov;
2106 i->iov_offset = base;
2107 }
2108}
Nick Piggin89e10782007-10-16 01:25:07 -07002109EXPORT_SYMBOL(iov_iter_advance);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002110
Nick Pigginafddba42007-10-16 01:25:01 -07002111/*
2112 * Fault in the first iovec of the given iov_iter, to a maximum length
2113 * of bytes. Returns 0 on success, or non-zero if the memory could not be
2114 * accessed (ie. because it is an invalid address).
2115 *
2116 * writev-intensive code may want this to prefault several iovecs -- that
2117 * would be possible (callers must not rely on the fact that _only_ the
2118 * first iovec will be faulted with the current implementation).
2119 */
2120int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
Nick Piggin2f718ff2007-10-16 01:24:59 -07002121{
Nick Piggin2f718ff2007-10-16 01:24:59 -07002122 char __user *buf = i->iov->iov_base + i->iov_offset;
Nick Pigginafddba42007-10-16 01:25:01 -07002123 bytes = min(bytes, i->iov->iov_len - i->iov_offset);
2124 return fault_in_pages_readable(buf, bytes);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002125}
Nick Piggin89e10782007-10-16 01:25:07 -07002126EXPORT_SYMBOL(iov_iter_fault_in_readable);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002127
2128/*
2129 * Return the count of just the current iov_iter segment.
2130 */
2131size_t iov_iter_single_seg_count(struct iov_iter *i)
2132{
2133 const struct iovec *iov = i->iov;
2134 if (i->nr_segs == 1)
2135 return i->count;
2136 else
2137 return min(i->count, iov->iov_len - i->iov_offset);
2138}
Nick Piggin89e10782007-10-16 01:25:07 -07002139EXPORT_SYMBOL(iov_iter_single_seg_count);
Nick Piggin2f718ff2007-10-16 01:24:59 -07002140
2141/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 * Performs necessary checks before doing a write
2143 *
Randy Dunlap485bb992006-06-23 02:03:49 -07002144 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 * Returns appropriate error code that caller should return or
2146 * zero in case that write should be allowed.
2147 */
2148inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
2149{
2150 struct inode *inode = file->f_mapping->host;
Jiri Slaby59e99e52010-03-05 13:41:44 -08002151 unsigned long limit = rlimit(RLIMIT_FSIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152
2153 if (unlikely(*pos < 0))
2154 return -EINVAL;
2155
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 if (!isblk) {
2157 /* FIXME: this is for backwards compatibility with 2.4 */
2158 if (file->f_flags & O_APPEND)
2159 *pos = i_size_read(inode);
2160
2161 if (limit != RLIM_INFINITY) {
2162 if (*pos >= limit) {
2163 send_sig(SIGXFSZ, current, 0);
2164 return -EFBIG;
2165 }
2166 if (*count > limit - (typeof(limit))*pos) {
2167 *count = limit - (typeof(limit))*pos;
2168 }
2169 }
2170 }
2171
2172 /*
2173 * LFS rule
2174 */
2175 if (unlikely(*pos + *count > MAX_NON_LFS &&
2176 !(file->f_flags & O_LARGEFILE))) {
2177 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178 return -EFBIG;
2179 }
2180 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2181 *count = MAX_NON_LFS - (unsigned long)*pos;
2182 }
2183 }
2184
2185 /*
2186 * Are we about to exceed the fs block limit ?
2187 *
2188 * If we have written data it becomes a short write. If we have
2189 * exceeded without writing data we send a signal and return EFBIG.
2190 * Linus frestrict idea will clean these up nicely..
2191 */
2192 if (likely(!isblk)) {
2193 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2194 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195 return -EFBIG;
2196 }
2197 /* zero-length writes at ->s_maxbytes are OK */
2198 }
2199
2200 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2201 *count = inode->i_sb->s_maxbytes - *pos;
2202 } else {
David Howells93614012006-09-30 20:45:40 +02002203#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002204 loff_t isize;
2205 if (bdev_read_only(I_BDEV(inode)))
2206 return -EPERM;
2207 isize = i_size_read(inode);
2208 if (*pos >= isize) {
2209 if (*count || *pos > isize)
2210 return -ENOSPC;
2211 }
2212
2213 if (*pos + *count > isize)
2214 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002215#else
2216 return -EPERM;
2217#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 }
2219 return 0;
2220}
2221EXPORT_SYMBOL(generic_write_checks);
2222
Nick Pigginafddba42007-10-16 01:25:01 -07002223int pagecache_write_begin(struct file *file, struct address_space *mapping,
2224 loff_t pos, unsigned len, unsigned flags,
2225 struct page **pagep, void **fsdata)
2226{
2227 const struct address_space_operations *aops = mapping->a_ops;
2228
Nick Piggin4e02ed42008-10-29 14:00:55 -07002229 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002230 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002231}
2232EXPORT_SYMBOL(pagecache_write_begin);
2233
2234int pagecache_write_end(struct file *file, struct address_space *mapping,
2235 loff_t pos, unsigned len, unsigned copied,
2236 struct page *page, void *fsdata)
2237{
2238 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002239
Nick Piggin4e02ed42008-10-29 14:00:55 -07002240 mark_page_accessed(page);
2241 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002242}
2243EXPORT_SYMBOL(pagecache_write_end);
2244
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245ssize_t
2246generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
2247 unsigned long *nr_segs, loff_t pos, loff_t *ppos,
2248 size_t count, size_t ocount)
2249{
2250 struct file *file = iocb->ki_filp;
2251 struct address_space *mapping = file->f_mapping;
2252 struct inode *inode = mapping->host;
2253 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002254 size_t write_len;
2255 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002256
2257 if (count != ocount)
2258 *nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
2259
Christoph Hellwiga969e902008-07-23 21:27:04 -07002260 write_len = iov_length(iov, *nr_segs);
2261 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002262
Nick Piggin48b47c52009-01-06 14:40:22 -08002263 written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002264 if (written)
2265 goto out;
2266
2267 /*
2268 * After a write we want buffered reads to be sure to go to disk to get
2269 * the new data. We invalidate clean cached page from the region we're
2270 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002271 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002272 */
2273 if (mapping->nrpages) {
2274 written = invalidate_inode_pages2_range(mapping,
2275 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002276 /*
2277 * If a page can not be invalidated, return 0 to fall back
2278 * to buffered write.
2279 */
2280 if (written) {
2281 if (written == -EBUSY)
2282 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002283 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002284 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002285 }
2286
2287 written = mapping->a_ops->direct_IO(WRITE, iocb, iov, pos, *nr_segs);
2288
2289 /*
2290 * Finally, try again to invalidate clean pages which might have been
2291 * cached by non-direct readahead, or faulted in by get_user_pages()
2292 * if the source of the write was an mmap'ed region of the file
2293 * we're writing. Either one is a pretty crazy thing to do,
2294 * so we don't support it 100%. If this invalidation
2295 * fails, tough, the write still worked...
2296 */
2297 if (mapping->nrpages) {
2298 invalidate_inode_pages2_range(mapping,
2299 pos >> PAGE_CACHE_SHIFT, end);
2300 }
2301
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302 if (written > 0) {
Namhyung Kim01166512010-10-26 14:21:58 -07002303 pos += written;
2304 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2305 i_size_write(inode, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306 mark_inode_dirty(inode);
2307 }
Namhyung Kim01166512010-10-26 14:21:58 -07002308 *ppos = pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002309 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002310out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002311 return written;
2312}
2313EXPORT_SYMBOL(generic_file_direct_write);
2314
Nick Piggineb2be182007-10-16 01:24:57 -07002315/*
2316 * Find or create a page at the given pagecache position. Return the locked
2317 * page. This function is specifically for buffered writes.
2318 */
Nick Piggin54566b22009-01-04 12:00:53 -08002319struct page *grab_cache_page_write_begin(struct address_space *mapping,
2320 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07002321{
2322 int status;
2323 struct page *page;
Nick Piggin54566b22009-01-04 12:00:53 -08002324 gfp_t gfp_notmask = 0;
2325 if (flags & AOP_FLAG_NOFS)
2326 gfp_notmask = __GFP_FS;
Nick Piggineb2be182007-10-16 01:24:57 -07002327repeat:
2328 page = find_lock_page(mapping, index);
Steven Rostedtc585a262011-01-13 15:46:18 -08002329 if (page)
Nick Piggineb2be182007-10-16 01:24:57 -07002330 return page;
2331
Nick Piggin54566b22009-01-04 12:00:53 -08002332 page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002333 if (!page)
2334 return NULL;
Nick Piggin54566b22009-01-04 12:00:53 -08002335 status = add_to_page_cache_lru(page, mapping, index,
2336 GFP_KERNEL & ~gfp_notmask);
Nick Piggineb2be182007-10-16 01:24:57 -07002337 if (unlikely(status)) {
2338 page_cache_release(page);
2339 if (status == -EEXIST)
2340 goto repeat;
2341 return NULL;
2342 }
2343 return page;
2344}
Nick Piggin54566b22009-01-04 12:00:53 -08002345EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07002346
Nick Pigginafddba42007-10-16 01:25:01 -07002347static ssize_t generic_perform_write(struct file *file,
2348 struct iov_iter *i, loff_t pos)
2349{
2350 struct address_space *mapping = file->f_mapping;
2351 const struct address_space_operations *a_ops = mapping->a_ops;
2352 long status = 0;
2353 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002354 unsigned int flags = 0;
2355
2356 /*
2357 * Copies from kernel address space cannot fail (NFSD is a big user).
2358 */
2359 if (segment_eq(get_fs(), KERNEL_DS))
2360 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002361
2362 do {
2363 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07002364 unsigned long offset; /* Offset into pagecache page */
2365 unsigned long bytes; /* Bytes to write to page */
2366 size_t copied; /* Bytes copied from user */
2367 void *fsdata;
2368
2369 offset = (pos & (PAGE_CACHE_SIZE - 1));
Nick Pigginafddba42007-10-16 01:25:01 -07002370 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2371 iov_iter_count(i));
2372
2373again:
2374
2375 /*
2376 * Bring in the user page that we will copy from _first_.
2377 * Otherwise there's a nasty deadlock on copying from the
2378 * same page as we're writing to, without it being marked
2379 * up-to-date.
2380 *
2381 * Not only is this an optimisation, but it is also required
2382 * to check that the address is actually valid, when atomic
2383 * usercopies are used, below.
2384 */
2385 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2386 status = -EFAULT;
2387 break;
2388 }
2389
Nick Piggin674b8922007-10-16 01:25:03 -07002390 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002391 &page, &fsdata);
2392 if (unlikely(status))
2393 break;
2394
anfei zhou931e80e2010-02-02 13:44:02 -08002395 if (mapping_writably_mapped(mapping))
2396 flush_dcache_page(page);
2397
Nick Pigginafddba42007-10-16 01:25:01 -07002398 pagefault_disable();
2399 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
2400 pagefault_enable();
2401 flush_dcache_page(page);
2402
Josef Bacikc8236db2009-07-05 12:08:18 -07002403 mark_page_accessed(page);
Nick Pigginafddba42007-10-16 01:25:01 -07002404 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2405 page, fsdata);
2406 if (unlikely(status < 0))
2407 break;
2408 copied = status;
2409
2410 cond_resched();
2411
Nick Piggin124d3b72008-02-02 15:01:17 +01002412 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002413 if (unlikely(copied == 0)) {
2414 /*
2415 * If we were unable to copy any data at all, we must
2416 * fall back to a single segment length write.
2417 *
2418 * If we didn't fallback here, we could livelock
2419 * because not all segments in the iov can be copied at
2420 * once without a pagefault.
2421 */
2422 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2423 iov_iter_single_seg_count(i));
2424 goto again;
2425 }
Nick Pigginafddba42007-10-16 01:25:01 -07002426 pos += copied;
2427 written += copied;
2428
2429 balance_dirty_pages_ratelimited(mapping);
2430
2431 } while (iov_iter_count(i));
2432
2433 return written ? written : status;
2434}
2435
2436ssize_t
2437generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
2438 unsigned long nr_segs, loff_t pos, loff_t *ppos,
2439 size_t count, ssize_t written)
2440{
2441 struct file *file = iocb->ki_filp;
Nick Pigginafddba42007-10-16 01:25:01 -07002442 ssize_t status;
2443 struct iov_iter i;
2444
2445 iov_iter_init(&i, iov, nr_segs, count, written);
Nick Piggin4e02ed42008-10-29 14:00:55 -07002446 status = generic_perform_write(file, &i, pos);
Nick Pigginafddba42007-10-16 01:25:01 -07002447
Linus Torvalds1da177e2005-04-16 15:20:36 -07002448 if (likely(status >= 0)) {
Nick Pigginafddba42007-10-16 01:25:01 -07002449 written += status;
2450 *ppos = pos + status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002451 }
2452
Linus Torvalds1da177e2005-04-16 15:20:36 -07002453 return written ? written : status;
2454}
2455EXPORT_SYMBOL(generic_file_buffered_write);
2456
Jan Karae4dd9de2009-08-17 18:10:06 +02002457/**
2458 * __generic_file_aio_write - write data to a file
2459 * @iocb: IO state structure (file, offset, etc.)
2460 * @iov: vector with data to write
2461 * @nr_segs: number of segments in the vector
2462 * @ppos: position where to write
2463 *
2464 * This function does all the work needed for actually writing data to a
2465 * file. It does all basic checks, removes SUID from the file, updates
2466 * modification times and calls proper subroutines depending on whether we
2467 * do direct IO or a standard buffered write.
2468 *
2469 * It expects i_mutex to be grabbed unless we work on a block device or similar
2470 * object which does not need locking at all.
2471 *
2472 * This function does *not* take care of syncing data in case of O_SYNC write.
2473 * A caller has to handle it. This is mainly due to the fact that we want to
2474 * avoid syncing under i_mutex.
2475 */
2476ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2477 unsigned long nr_segs, loff_t *ppos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002478{
2479 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002480 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002481 size_t ocount; /* original count */
2482 size_t count; /* after file limit checks */
2483 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484 loff_t pos;
2485 ssize_t written;
2486 ssize_t err;
2487
2488 ocount = 0;
Dmitriy Monakhov0ceb3312007-05-08 00:23:02 -07002489 err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
2490 if (err)
2491 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002492
2493 count = ocount;
2494 pos = *ppos;
2495
2496 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
2497
2498 /* We can write back this queue in page reclaim */
2499 current->backing_dev_info = mapping->backing_dev_info;
2500 written = 0;
2501
2502 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2503 if (err)
2504 goto out;
2505
2506 if (count == 0)
2507 goto out;
2508
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002509 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510 if (err)
2511 goto out;
2512
Christoph Hellwig870f4812006-01-09 20:52:01 -08002513 file_update_time(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514
2515 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2516 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002517 loff_t endbyte;
2518 ssize_t written_buffered;
2519
2520 written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
2521 ppos, count, ocount);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522 if (written < 0 || written == count)
2523 goto out;
2524 /*
2525 * direct-io write to a hole: fall through to buffered I/O
2526 * for completing the rest of the request.
2527 */
2528 pos += written;
2529 count -= written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002530 written_buffered = generic_file_buffered_write(iocb, iov,
2531 nr_segs, pos, ppos, count,
2532 written);
2533 /*
2534 * If generic_file_buffered_write() retuned a synchronous error
2535 * then we want to return the number of bytes which were
2536 * direct-written, or the error code if that was zero. Note
2537 * that this differs from normal direct-io semantics, which
2538 * will return -EFOO even if some bytes were written.
2539 */
2540 if (written_buffered < 0) {
2541 err = written_buffered;
2542 goto out;
2543 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002544
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002545 /*
2546 * We need to ensure that the page cache pages are written to
2547 * disk and invalidated to preserve the expected O_DIRECT
2548 * semantics.
2549 */
2550 endbyte = pos + written_buffered - written - 1;
Christoph Hellwigc05c4ed2009-09-23 15:07:30 +02002551 err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002552 if (err == 0) {
2553 written = written_buffered;
2554 invalidate_mapping_pages(mapping,
2555 pos >> PAGE_CACHE_SHIFT,
2556 endbyte >> PAGE_CACHE_SHIFT);
2557 } else {
2558 /*
2559 * We don't know how much we wrote, so just return
2560 * the number of bytes which were direct-written
2561 */
2562 }
2563 } else {
2564 written = generic_file_buffered_write(iocb, iov, nr_segs,
2565 pos, ppos, count, written);
2566 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002567out:
2568 current->backing_dev_info = NULL;
2569 return written ? written : err;
2570}
Jan Karae4dd9de2009-08-17 18:10:06 +02002571EXPORT_SYMBOL(__generic_file_aio_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002572
Jan Karae4dd9de2009-08-17 18:10:06 +02002573/**
2574 * generic_file_aio_write - write data to a file
2575 * @iocb: IO state structure
2576 * @iov: vector with data to write
2577 * @nr_segs: number of segments in the vector
2578 * @pos: position in file where to write
2579 *
2580 * This is a wrapper around __generic_file_aio_write() to be used by most
2581 * filesystems. It takes care of syncing the file in case of O_SYNC file
2582 * and acquires i_mutex as needed.
2583 */
Badari Pulavarty027445c2006-09-30 23:28:46 -07002584ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
2585 unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002586{
2587 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02002588 struct inode *inode = file->f_mapping->host;
Jens Axboe55602dd2010-06-24 15:05:37 +02002589 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002590 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002591
2592 BUG_ON(iocb->ki_pos != pos);
2593
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002594 mutex_lock(&inode->i_mutex);
Jens Axboe55602dd2010-06-24 15:05:37 +02002595 blk_start_plug(&plug);
Jan Karae4dd9de2009-08-17 18:10:06 +02002596 ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002597 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002598
Jan Kara148f9482009-08-17 19:52:36 +02002599 if (ret > 0 || ret == -EIOCBQUEUED) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600 ssize_t err;
2601
Jan Kara148f9482009-08-17 19:52:36 +02002602 err = generic_write_sync(file, pos, ret);
Jan Karac7b50db2009-08-18 16:18:20 +02002603 if (err < 0 && ret > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002604 ret = err;
2605 }
Jens Axboe55602dd2010-06-24 15:05:37 +02002606 blk_finish_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002607 return ret;
2608}
2609EXPORT_SYMBOL(generic_file_aio_write);
2610
David Howellscf9a2ae2006-08-29 19:05:54 +01002611/**
2612 * try_to_release_page() - release old fs-specific metadata on a page
2613 *
2614 * @page: the page which the kernel is trying to free
2615 * @gfp_mask: memory allocation flags (and I/O mode)
2616 *
2617 * The address_space is to try to release any data against the page
2618 * (presumably at page->private). If the release was successful, return `1'.
2619 * Otherwise return zero.
2620 *
David Howells266cf652009-04-03 16:42:36 +01002621 * This may also be called if PG_fscache is set on a page, indicating that the
2622 * page is known to the local caching routines.
2623 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002624 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fdd2008-07-25 01:46:22 -07002625 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002626 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002627 */
2628int try_to_release_page(struct page *page, gfp_t gfp_mask)
2629{
2630 struct address_space * const mapping = page->mapping;
2631
2632 BUG_ON(!PageLocked(page));
2633 if (PageWriteback(page))
2634 return 0;
2635
2636 if (mapping && mapping->a_ops->releasepage)
2637 return mapping->a_ops->releasepage(page, gfp_mask);
2638 return try_to_free_buffers(page);
2639}
2640
2641EXPORT_SYMBOL(try_to_release_page);