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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 */
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040012#include <linux/export.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>
Paul Jackson44110fe2006-03-24 03:16:04 -080032#include <linux/cpuset.h>
Nick Piggin2f718ff2007-10-16 01:24:59 -070033#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
Johannes Weiner00501b52014-08-08 14:19:20 -070034#include <linux/hugetlb.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080035#include <linux/memcontrol.h>
Dan Magenheimerc515e1f2011-05-26 10:01:43 -060036#include <linux/cleancache.h>
Kirill A. Shutemovf1820362014-04-07 15:37:19 -070037#include <linux/rmap.h>
Nick Piggin0f8053a2006-03-22 00:08:33 -080038#include "internal.h"
39
Robert Jarzmikfe0bfaa2013-04-29 15:06:10 -070040#define CREATE_TRACE_POINTS
41#include <trace/events/filemap.h>
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 * FIXME: remove all knowledge of the buffer layer from the core VM
45 */
Jan Kara148f9482009-08-17 19:52:36 +020046#include <linux/buffer_head.h> /* for try_to_free_buffers */
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#include <asm/mman.h>
49
50/*
51 * Shared mappings implemented 30.11.1994. It's not fully working yet,
52 * though.
53 *
54 * Shared mappings now work. 15.8.1995 Bruno.
55 *
56 * finished 'unifying' the page and buffer cache and SMP-threaded the
57 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
58 *
59 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
60 */
61
62/*
63 * Lock ordering:
64 *
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070065 * ->i_mmap_mutex (truncate_pagecache)
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070067 * ->swap_lock (exclusive_swap_page, others)
68 * ->mapping->tree_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070069 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080070 * ->i_mutex
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070071 * ->i_mmap_mutex (truncate->unmap_mapping_range)
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 *
73 * ->mmap_sem
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070074 * ->i_mmap_mutex
Hugh Dickinsb8072f02005-10-29 18:16:41 -070075 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Linus Torvalds1da177e2005-04-16 15:20:36 -070076 * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
77 *
78 * ->mmap_sem
79 * ->lock_page (access_process_vm)
80 *
Al Viroccad2362014-02-11 22:36:48 -050081 * ->i_mutex (generic_perform_write)
Nick Piggin82591e62006-10-19 23:29:10 -070082 * ->mmap_sem (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 *
Christoph Hellwigf758eea2011-04-21 18:19:44 -060084 * bdi->wb.list_lock
Dave Chinnera66979a2011-03-22 22:23:41 +110085 * 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)
Christoph Hellwigf758eea2011-04-21 18:19:44 -0600102 * bdi.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)
Christoph Hellwigf758eea2011-04-21 18:19:44 -0600104 * bdi.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 Kleen9a3c5312012-03-21 16:34:09 -0700108 * ->i_mmap_mutex
109 * ->tasklist_lock (memory_failure, collect_procs_ao)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 */
111
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700112static void page_cache_tree_delete(struct address_space *mapping,
113 struct page *page, void *shadow)
114{
Johannes Weiner449dd692014-04-03 14:47:56 -0700115 struct radix_tree_node *node;
116 unsigned long index;
117 unsigned int offset;
118 unsigned int tag;
119 void **slot;
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700120
Johannes Weiner449dd692014-04-03 14:47:56 -0700121 VM_BUG_ON(!PageLocked(page));
122
123 __radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
124
125 if (shadow) {
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700126 mapping->nrshadows++;
127 /*
128 * Make sure the nrshadows update is committed before
129 * the nrpages update so that final truncate racing
130 * with reclaim does not see both counters 0 at the
131 * same time and miss a shadow entry.
132 */
133 smp_wmb();
Johannes Weiner449dd692014-04-03 14:47:56 -0700134 }
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700135 mapping->nrpages--;
Johannes Weiner449dd692014-04-03 14:47:56 -0700136
137 if (!node) {
138 /* Clear direct pointer tags in root node */
139 mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
140 radix_tree_replace_slot(slot, shadow);
141 return;
142 }
143
144 /* Clear tree tags for the removed page */
145 index = page->index;
146 offset = index & RADIX_TREE_MAP_MASK;
147 for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
148 if (test_bit(offset, node->tags[tag]))
149 radix_tree_tag_clear(&mapping->page_tree, index, tag);
150 }
151
152 /* Delete page, swap shadow entry */
153 radix_tree_replace_slot(slot, shadow);
154 workingset_node_pages_dec(node);
155 if (shadow)
156 workingset_node_shadows_inc(node);
157 else
158 if (__radix_tree_delete_node(&mapping->page_tree, node))
159 return;
160
161 /*
162 * Track node that only contains shadow entries.
163 *
164 * Avoid acquiring the list_lru lock if already tracked. The
165 * list_empty() test is safe as node->private_list is
166 * protected by mapping->tree_lock.
167 */
168 if (!workingset_node_pages(node) &&
169 list_empty(&node->private_list)) {
170 node->private_data = mapping;
171 list_lru_add(&workingset_shadow_nodes, &node->private_list);
172 }
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700173}
174
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175/*
Minchan Kime64a7822011-03-22 16:32:44 -0700176 * Delete a page from the page cache and free it. Caller has to make
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 * sure the page is locked and that nobody else uses it - or that usage
Nick Piggin19fd6232008-07-25 19:45:32 -0700178 * is safe. The caller must hold the mapping's tree_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 */
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700180void __delete_from_page_cache(struct page *page, void *shadow)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181{
182 struct address_space *mapping = page->mapping;
183
Robert Jarzmikfe0bfaa2013-04-29 15:06:10 -0700184 trace_mm_filemap_delete_from_page_cache(page);
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600185 /*
186 * if we're uptodate, flush out into the cleancache, otherwise
187 * invalidate any existing cleancache entries. We can't leave
188 * stale data around in the cleancache once our page is gone
189 */
190 if (PageUptodate(page) && PageMappedToDisk(page))
191 cleancache_put_page(page);
192 else
Dan Magenheimer31677602011-09-21 11:56:28 -0400193 cleancache_invalidate_page(mapping, page);
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600194
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700195 page_cache_tree_delete(mapping, page, shadow);
196
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 page->mapping = NULL;
Hugh Dickinsb85e0ef2011-07-25 17:12:25 -0700198 /* Leave page->index set: truncation lookup relies upon it */
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700199
Christoph Lameter347ce432006-06-30 01:55:35 -0700200 __dec_zone_page_state(page, NR_FILE_PAGES);
KOSAKI Motohiro4b021082009-09-21 17:01:33 -0700201 if (PageSwapBacked(page))
202 __dec_zone_page_state(page, NR_SHMEM);
Nick Piggin45426812007-07-15 23:38:12 -0700203 BUG_ON(page_mapped(page));
Linus Torvalds3a692792007-12-19 14:05:13 -0800204
205 /*
206 * Some filesystems seem to re-dirty the page even after
207 * the VM has canceled the dirty bit (eg ext3 journaling).
208 *
209 * Fix it up by doing a final dirty accounting check after
210 * having removed the page entirely.
211 */
212 if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
213 dec_zone_page_state(page, NR_FILE_DIRTY);
214 dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
215 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216}
217
Minchan Kim702cfbf2011-03-22 16:32:43 -0700218/**
219 * delete_from_page_cache - delete page from page cache
220 * @page: the page which the kernel is trying to remove from page cache
221 *
222 * This must be called only on pages that have been verified to be in the page
223 * cache and locked. It will never put the page into the free list, the caller
224 * has a reference on the page.
225 */
226void delete_from_page_cache(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227{
228 struct address_space *mapping = page->mapping;
Linus Torvalds6072d132010-12-01 13:35:19 -0500229 void (*freepage)(struct page *);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230
Matt Mackallcd7619d2005-05-01 08:59:01 -0700231 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
Linus Torvalds6072d132010-12-01 13:35:19 -0500233 freepage = mapping->a_ops->freepage;
Nick Piggin19fd6232008-07-25 19:45:32 -0700234 spin_lock_irq(&mapping->tree_lock);
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700235 __delete_from_page_cache(page, NULL);
Nick Piggin19fd6232008-07-25 19:45:32 -0700236 spin_unlock_irq(&mapping->tree_lock);
Linus Torvalds6072d132010-12-01 13:35:19 -0500237
238 if (freepage)
239 freepage(page);
Minchan Kim97cecb52011-03-22 16:30:53 -0700240 page_cache_release(page);
241}
242EXPORT_SYMBOL(delete_from_page_cache);
243
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700244static int filemap_check_errors(struct address_space *mapping)
245{
246 int ret = 0;
247 /* Check for outstanding write errors */
Jens Axboe7fcbbaf2014-05-22 11:54:16 -0700248 if (test_bit(AS_ENOSPC, &mapping->flags) &&
249 test_and_clear_bit(AS_ENOSPC, &mapping->flags))
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700250 ret = -ENOSPC;
Jens Axboe7fcbbaf2014-05-22 11:54:16 -0700251 if (test_bit(AS_EIO, &mapping->flags) &&
252 test_and_clear_bit(AS_EIO, &mapping->flags))
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700253 ret = -EIO;
254 return ret;
255}
256
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700258 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700259 * @mapping: address space structure to write
260 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800261 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700262 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700264 * Start writeback against all of a mapping's dirty pages that lie
265 * within the byte offsets <start, end> inclusive.
266 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700268 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 * these two operations is that if a dirty page/buffer is encountered, it must
270 * be waited upon, and not just skipped over.
271 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800272int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
273 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274{
275 int ret;
276 struct writeback_control wbc = {
277 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800278 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700279 .range_start = start,
280 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 };
282
283 if (!mapping_cap_writeback_dirty(mapping))
284 return 0;
285
286 ret = do_writepages(mapping, &wbc);
287 return ret;
288}
289
290static inline int __filemap_fdatawrite(struct address_space *mapping,
291 int sync_mode)
292{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700293 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294}
295
296int filemap_fdatawrite(struct address_space *mapping)
297{
298 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
299}
300EXPORT_SYMBOL(filemap_fdatawrite);
301
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400302int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800303 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304{
305 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
306}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400307EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308
Randy Dunlap485bb992006-06-23 02:03:49 -0700309/**
310 * filemap_flush - mostly a non-blocking flush
311 * @mapping: target address_space
312 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 * This is a mostly non-blocking flush. Not suitable for data-integrity
314 * purposes - I/O may not be started against all dirty pages.
315 */
316int filemap_flush(struct address_space *mapping)
317{
318 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
319}
320EXPORT_SYMBOL(filemap_flush);
321
Randy Dunlap485bb992006-06-23 02:03:49 -0700322/**
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200323 * filemap_fdatawait_range - wait for writeback to complete
324 * @mapping: address space structure to wait for
325 * @start_byte: offset in bytes where the range starts
326 * @end_byte: offset in bytes where the range ends (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -0700327 *
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200328 * Walk the list of under-writeback pages of the given address space
329 * in the given range and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330 */
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200331int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
332 loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333{
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200334 pgoff_t index = start_byte >> PAGE_CACHE_SHIFT;
335 pgoff_t end = end_byte >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 struct pagevec pvec;
337 int nr_pages;
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700338 int ret2, ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200340 if (end_byte < start_byte)
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700341 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342
343 pagevec_init(&pvec, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 while ((index <= end) &&
345 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
346 PAGECACHE_TAG_WRITEBACK,
347 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
348 unsigned i;
349
350 for (i = 0; i < nr_pages; i++) {
351 struct page *page = pvec.pages[i];
352
353 /* until radix tree lookup accepts end_index */
354 if (page->index > end)
355 continue;
356
357 wait_on_page_writeback(page);
Rik van Riel212260a2011-01-13 15:46:06 -0800358 if (TestClearPageError(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 ret = -EIO;
360 }
361 pagevec_release(&pvec);
362 cond_resched();
363 }
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700364out:
365 ret2 = filemap_check_errors(mapping);
366 if (!ret)
367 ret = ret2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368
369 return ret;
370}
Jan Karad3bccb6f2009-08-17 19:30:27 +0200371EXPORT_SYMBOL(filemap_fdatawait_range);
372
373/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700374 * filemap_fdatawait - wait for all under-writeback pages to complete
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 * @mapping: address space structure to wait for
Randy Dunlap485bb992006-06-23 02:03:49 -0700376 *
377 * Walk the list of under-writeback pages of the given address space
378 * and wait for all of them.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 */
380int filemap_fdatawait(struct address_space *mapping)
381{
382 loff_t i_size = i_size_read(mapping->host);
383
384 if (i_size == 0)
385 return 0;
386
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200387 return filemap_fdatawait_range(mapping, 0, i_size - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388}
389EXPORT_SYMBOL(filemap_fdatawait);
390
391int filemap_write_and_wait(struct address_space *mapping)
392{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800393 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394
395 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800396 err = filemap_fdatawrite(mapping);
397 /*
398 * Even if the above returned error, the pages may be
399 * written partially (e.g. -ENOSPC), so we wait for it.
400 * But the -EIO is special case, it may indicate the worst
401 * thing (e.g. bug) happened, so we avoid waiting for it.
402 */
403 if (err != -EIO) {
404 int err2 = filemap_fdatawait(mapping);
405 if (!err)
406 err = err2;
407 }
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700408 } else {
409 err = filemap_check_errors(mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800411 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412}
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800413EXPORT_SYMBOL(filemap_write_and_wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414
Randy Dunlap485bb992006-06-23 02:03:49 -0700415/**
416 * filemap_write_and_wait_range - write out & wait on a file range
417 * @mapping: the address_space for the pages
418 * @lstart: offset in bytes where the range starts
419 * @lend: offset in bytes where the range ends (inclusive)
420 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800421 * Write out and wait upon file offsets lstart->lend, inclusive.
422 *
423 * Note that `lend' is inclusive (describes the last byte to be written) so
424 * that this function can be used to write to the very end-of-file (end = -1).
425 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426int filemap_write_and_wait_range(struct address_space *mapping,
427 loff_t lstart, loff_t lend)
428{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800429 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430
431 if (mapping->nrpages) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800432 err = __filemap_fdatawrite_range(mapping, lstart, lend,
433 WB_SYNC_ALL);
434 /* See comment of filemap_write_and_wait() */
435 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200436 int err2 = filemap_fdatawait_range(mapping,
437 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800438 if (!err)
439 err = err2;
440 }
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700441 } else {
442 err = filemap_check_errors(mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800444 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445}
Chris Masonf6995582009-04-15 13:22:37 -0400446EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447
Randy Dunlap485bb992006-06-23 02:03:49 -0700448/**
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700449 * replace_page_cache_page - replace a pagecache page with a new one
450 * @old: page to be replaced
451 * @new: page to replace with
452 * @gfp_mask: allocation mode
453 *
454 * This function replaces a page in the pagecache with a new one. On
455 * success it acquires the pagecache reference for the new page and
456 * drops it for the old page. Both the old and new pages must be
457 * locked. This function does not add the new page to the LRU, the
458 * caller must do that.
459 *
460 * The remove + add is atomic. The only way this function can fail is
461 * memory allocation failure.
462 */
463int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
464{
465 int error;
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700466
Sasha Levin309381fea2014-01-23 15:52:54 -0800467 VM_BUG_ON_PAGE(!PageLocked(old), old);
468 VM_BUG_ON_PAGE(!PageLocked(new), new);
469 VM_BUG_ON_PAGE(new->mapping, new);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700470
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700471 error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
472 if (!error) {
473 struct address_space *mapping = old->mapping;
474 void (*freepage)(struct page *);
475
476 pgoff_t offset = old->index;
477 freepage = mapping->a_ops->freepage;
478
479 page_cache_get(new);
480 new->mapping = mapping;
481 new->index = offset;
482
483 spin_lock_irq(&mapping->tree_lock);
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700484 __delete_from_page_cache(old, NULL);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700485 error = radix_tree_insert(&mapping->page_tree, offset, new);
486 BUG_ON(error);
487 mapping->nrpages++;
488 __inc_zone_page_state(new, NR_FILE_PAGES);
489 if (PageSwapBacked(new))
490 __inc_zone_page_state(new, NR_SHMEM);
491 spin_unlock_irq(&mapping->tree_lock);
Johannes Weiner0a31bc92014-08-08 14:19:22 -0700492 mem_cgroup_migrate(old, new, true);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700493 radix_tree_preload_end();
494 if (freepage)
495 freepage(old);
496 page_cache_release(old);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700497 }
498
499 return error;
500}
501EXPORT_SYMBOL_GPL(replace_page_cache_page);
502
Johannes Weiner0cd61442014-04-03 14:47:46 -0700503static int page_cache_tree_insert(struct address_space *mapping,
Johannes Weinera5289102014-04-03 14:47:51 -0700504 struct page *page, void **shadowp)
Johannes Weiner0cd61442014-04-03 14:47:46 -0700505{
Johannes Weiner449dd692014-04-03 14:47:56 -0700506 struct radix_tree_node *node;
Johannes Weiner0cd61442014-04-03 14:47:46 -0700507 void **slot;
508 int error;
509
Johannes Weiner449dd692014-04-03 14:47:56 -0700510 error = __radix_tree_create(&mapping->page_tree, page->index,
511 &node, &slot);
512 if (error)
513 return error;
514 if (*slot) {
Johannes Weiner0cd61442014-04-03 14:47:46 -0700515 void *p;
516
517 p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
518 if (!radix_tree_exceptional_entry(p))
519 return -EEXIST;
Johannes Weinera5289102014-04-03 14:47:51 -0700520 if (shadowp)
521 *shadowp = p;
Johannes Weiner449dd692014-04-03 14:47:56 -0700522 mapping->nrshadows--;
523 if (node)
524 workingset_node_shadows_dec(node);
Johannes Weiner0cd61442014-04-03 14:47:46 -0700525 }
Johannes Weiner449dd692014-04-03 14:47:56 -0700526 radix_tree_replace_slot(slot, page);
527 mapping->nrpages++;
528 if (node) {
529 workingset_node_pages_inc(node);
530 /*
531 * Don't track node that contains actual pages.
532 *
533 * Avoid acquiring the list_lru lock if already
534 * untracked. The list_empty() test is safe as
535 * node->private_list is protected by
536 * mapping->tree_lock.
537 */
538 if (!list_empty(&node->private_list))
539 list_lru_del(&workingset_shadow_nodes,
540 &node->private_list);
541 }
542 return 0;
Johannes Weiner0cd61442014-04-03 14:47:46 -0700543}
544
Johannes Weinera5289102014-04-03 14:47:51 -0700545static int __add_to_page_cache_locked(struct page *page,
546 struct address_space *mapping,
547 pgoff_t offset, gfp_t gfp_mask,
548 void **shadowp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549{
Johannes Weiner00501b52014-08-08 14:19:20 -0700550 int huge = PageHuge(page);
551 struct mem_cgroup *memcg;
Nick Piggine2867812008-07-25 19:45:30 -0700552 int error;
553
Sasha Levin309381fea2014-01-23 15:52:54 -0800554 VM_BUG_ON_PAGE(!PageLocked(page), page);
555 VM_BUG_ON_PAGE(PageSwapBacked(page), page);
Nick Piggine2867812008-07-25 19:45:30 -0700556
Johannes Weiner00501b52014-08-08 14:19:20 -0700557 if (!huge) {
558 error = mem_cgroup_try_charge(page, current->mm,
559 gfp_mask, &memcg);
560 if (error)
561 return error;
562 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563
Jan Kara5e4c0d972013-09-11 14:26:05 -0700564 error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM);
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700565 if (error) {
Johannes Weiner00501b52014-08-08 14:19:20 -0700566 if (!huge)
567 mem_cgroup_cancel_charge(page, memcg);
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700568 return error;
569 }
570
571 page_cache_get(page);
572 page->mapping = mapping;
573 page->index = offset;
574
575 spin_lock_irq(&mapping->tree_lock);
Johannes Weinera5289102014-04-03 14:47:51 -0700576 error = page_cache_tree_insert(mapping, page, shadowp);
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700577 radix_tree_preload_end();
578 if (unlikely(error))
579 goto err_insert;
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700580 __inc_zone_page_state(page, NR_FILE_PAGES);
581 spin_unlock_irq(&mapping->tree_lock);
Johannes Weiner00501b52014-08-08 14:19:20 -0700582 if (!huge)
583 mem_cgroup_commit_charge(page, memcg, false);
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700584 trace_mm_filemap_add_to_page_cache(page);
585 return 0;
586err_insert:
587 page->mapping = NULL;
588 /* Leave page->index set: truncation relies upon it */
589 spin_unlock_irq(&mapping->tree_lock);
Johannes Weiner00501b52014-08-08 14:19:20 -0700590 if (!huge)
591 mem_cgroup_cancel_charge(page, memcg);
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700592 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 return error;
594}
Johannes Weinera5289102014-04-03 14:47:51 -0700595
596/**
597 * add_to_page_cache_locked - add a locked page to the pagecache
598 * @page: page to add
599 * @mapping: the page's address_space
600 * @offset: page index
601 * @gfp_mask: page allocation mode
602 *
603 * This function is used to add a page to the pagecache. It must be locked.
604 * This function does not add the page to the LRU. The caller must do that.
605 */
606int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
607 pgoff_t offset, gfp_t gfp_mask)
608{
609 return __add_to_page_cache_locked(page, mapping, offset,
610 gfp_mask, NULL);
611}
Nick Piggine2867812008-07-25 19:45:30 -0700612EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613
614int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400615 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616{
Johannes Weinera5289102014-04-03 14:47:51 -0700617 void *shadow = NULL;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700618 int ret;
619
Johannes Weinera5289102014-04-03 14:47:51 -0700620 __set_page_locked(page);
621 ret = __add_to_page_cache_locked(page, mapping, offset,
622 gfp_mask, &shadow);
623 if (unlikely(ret))
624 __clear_page_locked(page);
625 else {
626 /*
627 * The page might have been evicted from cache only
628 * recently, in which case it should be activated like
629 * any other repeatedly accessed page.
630 */
631 if (shadow && workingset_refault(shadow)) {
632 SetPageActive(page);
633 workingset_activation(page);
634 } else
635 ClearPageActive(page);
636 lru_cache_add(page);
637 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 return ret;
639}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300640EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641
Paul Jackson44110fe2006-03-24 03:16:04 -0800642#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700643struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800644{
Miao Xiec0ff7452010-05-24 14:32:08 -0700645 int n;
646 struct page *page;
647
Paul Jackson44110fe2006-03-24 03:16:04 -0800648 if (cpuset_do_page_mem_spread()) {
Mel Gormancc9a6c82012-03-21 16:34:11 -0700649 unsigned int cpuset_mems_cookie;
650 do {
Mel Gormand26914d2014-04-03 14:47:24 -0700651 cpuset_mems_cookie = read_mems_allowed_begin();
Mel Gormancc9a6c82012-03-21 16:34:11 -0700652 n = cpuset_mem_spread_node();
653 page = alloc_pages_exact_node(n, gfp, 0);
Mel Gormand26914d2014-04-03 14:47:24 -0700654 } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
Mel Gormancc9a6c82012-03-21 16:34:11 -0700655
Miao Xiec0ff7452010-05-24 14:32:08 -0700656 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800657 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700658 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800659}
Nick Piggin2ae88142006-10-28 10:38:23 -0700660EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800661#endif
662
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663/*
664 * In order to wait for pages to become available there must be
665 * waitqueues associated with pages. By using a hash table of
666 * waitqueues where the bucket discipline is to maintain all
667 * waiters on the same queue and wake all when any of the pages
668 * become available, and for the woken contexts to check to be
669 * sure the appropriate page became available, this saves space
670 * at a cost of "thundering herd" phenomena during rare hash
671 * collisions.
672 */
NeilBrowna4796e32014-09-24 11:28:32 +1000673wait_queue_head_t *page_waitqueue(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674{
675 const struct zone *zone = page_zone(page);
676
677 return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
678}
NeilBrowna4796e32014-09-24 11:28:32 +1000679EXPORT_SYMBOL(page_waitqueue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
Harvey Harrison920c7a52008-02-04 22:29:26 -0800681void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682{
683 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
684
685 if (test_bit(bit_nr, &page->flags))
NeilBrown74316202014-07-07 15:16:04 +1000686 __wait_on_bit(page_waitqueue(page), &wait, bit_wait_io,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 TASK_UNINTERRUPTIBLE);
688}
689EXPORT_SYMBOL(wait_on_page_bit);
690
KOSAKI Motohirof62e00c2011-05-24 17:11:29 -0700691int wait_on_page_bit_killable(struct page *page, int bit_nr)
692{
693 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
694
695 if (!test_bit(bit_nr, &page->flags))
696 return 0;
697
698 return __wait_on_bit(page_waitqueue(page), &wait,
NeilBrown74316202014-07-07 15:16:04 +1000699 bit_wait_io, TASK_KILLABLE);
KOSAKI Motohirof62e00c2011-05-24 17:11:29 -0700700}
701
NeilBrowncbbce822014-09-25 13:55:19 +1000702int wait_on_page_bit_killable_timeout(struct page *page,
703 int bit_nr, unsigned long timeout)
704{
705 DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
706
707 wait.key.timeout = jiffies + timeout;
708 if (!test_bit(bit_nr, &page->flags))
709 return 0;
710 return __wait_on_bit(page_waitqueue(page), &wait,
711 bit_wait_io_timeout, TASK_KILLABLE);
712}
713EXPORT_SYMBOL_GPL(wait_on_page_bit_killable_timeout);
714
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715/**
David Howells385e1ca5f2009-04-03 16:42:39 +0100716 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -0700717 * @page: Page defining the wait queue of interest
718 * @waiter: Waiter to add to the queue
David Howells385e1ca5f2009-04-03 16:42:39 +0100719 *
720 * Add an arbitrary @waiter to the wait queue for the nominated @page.
721 */
722void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
723{
724 wait_queue_head_t *q = page_waitqueue(page);
725 unsigned long flags;
726
727 spin_lock_irqsave(&q->lock, flags);
728 __add_wait_queue(q, waiter);
729 spin_unlock_irqrestore(&q->lock, flags);
730}
731EXPORT_SYMBOL_GPL(add_page_wait_queue);
732
733/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700734 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 * @page: the page
736 *
737 * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
738 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
Masanari Iidada3dae52014-09-09 01:27:23 +0900739 * mechanism between PageLocked pages and PageWriteback pages is shared.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
741 *
Nick Piggin8413ac92008-10-18 20:26:59 -0700742 * The mb is necessary to enforce ordering between the clear_bit and the read
743 * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800745void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746{
Sasha Levin309381fea2014-01-23 15:52:54 -0800747 VM_BUG_ON_PAGE(!PageLocked(page), page);
Nick Piggin8413ac92008-10-18 20:26:59 -0700748 clear_bit_unlock(PG_locked, &page->flags);
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100749 smp_mb__after_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 wake_up_page(page, PG_locked);
751}
752EXPORT_SYMBOL(unlock_page);
753
Randy Dunlap485bb992006-06-23 02:03:49 -0700754/**
755 * end_page_writeback - end writeback against a page
756 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 */
758void end_page_writeback(struct page *page)
759{
Mel Gorman888cf2d2014-06-04 16:10:34 -0700760 /*
761 * TestClearPageReclaim could be used here but it is an atomic
762 * operation and overkill in this particular case. Failing to
763 * shuffle a page marked for immediate reclaim is too mild to
764 * justify taking an atomic operation penalty at the end of
765 * ever page writeback.
766 */
767 if (PageReclaim(page)) {
768 ClearPageReclaim(page);
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700769 rotate_reclaimable_page(page);
Mel Gorman888cf2d2014-06-04 16:10:34 -0700770 }
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700771
772 if (!test_clear_page_writeback(page))
773 BUG();
774
Peter Zijlstra4e857c52014-03-17 18:06:10 +0100775 smp_mb__after_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 wake_up_page(page, PG_writeback);
777}
778EXPORT_SYMBOL(end_page_writeback);
779
Matthew Wilcox57d99842014-06-04 16:07:45 -0700780/*
781 * After completing I/O on a page, call this routine to update the page
782 * flags appropriately
783 */
784void page_endio(struct page *page, int rw, int err)
785{
786 if (rw == READ) {
787 if (!err) {
788 SetPageUptodate(page);
789 } else {
790 ClearPageUptodate(page);
791 SetPageError(page);
792 }
793 unlock_page(page);
794 } else { /* rw == WRITE */
795 if (err) {
796 SetPageError(page);
797 if (page->mapping)
798 mapping_set_error(page->mapping, err);
799 }
800 end_page_writeback(page);
801 }
802}
803EXPORT_SYMBOL_GPL(page_endio);
804
Randy Dunlap485bb992006-06-23 02:03:49 -0700805/**
806 * __lock_page - get a lock on the page, assuming we need to sleep to get it
807 * @page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800809void __lock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810{
811 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
812
NeilBrown74316202014-07-07 15:16:04 +1000813 __wait_on_bit_lock(page_waitqueue(page), &wait, bit_wait_io,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 TASK_UNINTERRUPTIBLE);
815}
816EXPORT_SYMBOL(__lock_page);
817
Harvey Harrisonb5606c22008-02-13 15:03:16 -0800818int __lock_page_killable(struct page *page)
Matthew Wilcox2687a352007-12-06 11:18:49 -0500819{
820 DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
821
822 return __wait_on_bit_lock(page_waitqueue(page), &wait,
NeilBrown74316202014-07-07 15:16:04 +1000823 bit_wait_io, TASK_KILLABLE);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500824}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300825EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -0500826
Paul Cassella9a95f3c2014-08-06 16:07:24 -0700827/*
828 * Return values:
829 * 1 - page is locked; mmap_sem is still held.
830 * 0 - page is not locked.
831 * mmap_sem has been released (up_read()), unless flags had both
832 * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
833 * which case mmap_sem is still held.
834 *
835 * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
836 * with the page locked and the mmap_sem unperturbed.
837 */
Michel Lespinassed065bd82010-10-26 14:21:57 -0700838int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
839 unsigned int flags)
840{
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -0700841 if (flags & FAULT_FLAG_ALLOW_RETRY) {
842 /*
843 * CAUTION! In this case, mmap_sem is not released
844 * even though return 0.
845 */
846 if (flags & FAULT_FLAG_RETRY_NOWAIT)
847 return 0;
848
849 up_read(&mm->mmap_sem);
850 if (flags & FAULT_FLAG_KILLABLE)
851 wait_on_page_locked_killable(page);
852 else
Gleb Natapov318b2752011-03-22 16:30:51 -0700853 wait_on_page_locked(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -0700854 return 0;
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -0700855 } else {
856 if (flags & FAULT_FLAG_KILLABLE) {
857 int ret;
858
859 ret = __lock_page_killable(page);
860 if (ret) {
861 up_read(&mm->mmap_sem);
862 return 0;
863 }
864 } else
865 __lock_page(page);
866 return 1;
Michel Lespinassed065bd82010-10-26 14:21:57 -0700867 }
868}
869
Randy Dunlap485bb992006-06-23 02:03:49 -0700870/**
Johannes Weinere7b563b2014-04-03 14:47:44 -0700871 * page_cache_next_hole - find the next hole (not-present entry)
872 * @mapping: mapping
873 * @index: index
874 * @max_scan: maximum range to search
875 *
876 * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the
877 * lowest indexed hole.
878 *
879 * Returns: the index of the hole if found, otherwise returns an index
880 * outside of the set specified (in which case 'return - index >=
881 * max_scan' will be true). In rare cases of index wrap-around, 0 will
882 * be returned.
883 *
884 * page_cache_next_hole may be called under rcu_read_lock. However,
885 * like radix_tree_gang_lookup, this will not atomically search a
886 * snapshot of the tree at a single point in time. For example, if a
887 * hole is created at index 5, then subsequently a hole is created at
888 * index 10, page_cache_next_hole covering both indexes may return 10
889 * if called under rcu_read_lock.
890 */
891pgoff_t page_cache_next_hole(struct address_space *mapping,
892 pgoff_t index, unsigned long max_scan)
893{
894 unsigned long i;
895
896 for (i = 0; i < max_scan; i++) {
Johannes Weiner0cd61442014-04-03 14:47:46 -0700897 struct page *page;
898
899 page = radix_tree_lookup(&mapping->page_tree, index);
900 if (!page || radix_tree_exceptional_entry(page))
Johannes Weinere7b563b2014-04-03 14:47:44 -0700901 break;
902 index++;
903 if (index == 0)
904 break;
905 }
906
907 return index;
908}
909EXPORT_SYMBOL(page_cache_next_hole);
910
911/**
912 * page_cache_prev_hole - find the prev hole (not-present entry)
913 * @mapping: mapping
914 * @index: index
915 * @max_scan: maximum range to search
916 *
917 * Search backwards in the range [max(index-max_scan+1, 0), index] for
918 * the first hole.
919 *
920 * Returns: the index of the hole if found, otherwise returns an index
921 * outside of the set specified (in which case 'index - return >=
922 * max_scan' will be true). In rare cases of wrap-around, ULONG_MAX
923 * will be returned.
924 *
925 * page_cache_prev_hole may be called under rcu_read_lock. However,
926 * like radix_tree_gang_lookup, this will not atomically search a
927 * snapshot of the tree at a single point in time. For example, if a
928 * hole is created at index 10, then subsequently a hole is created at
929 * index 5, page_cache_prev_hole covering both indexes may return 5 if
930 * called under rcu_read_lock.
931 */
932pgoff_t page_cache_prev_hole(struct address_space *mapping,
933 pgoff_t index, unsigned long max_scan)
934{
935 unsigned long i;
936
937 for (i = 0; i < max_scan; i++) {
Johannes Weiner0cd61442014-04-03 14:47:46 -0700938 struct page *page;
939
940 page = radix_tree_lookup(&mapping->page_tree, index);
941 if (!page || radix_tree_exceptional_entry(page))
Johannes Weinere7b563b2014-04-03 14:47:44 -0700942 break;
943 index--;
944 if (index == ULONG_MAX)
945 break;
946 }
947
948 return index;
949}
950EXPORT_SYMBOL(page_cache_prev_hole);
951
952/**
Johannes Weiner0cd61442014-04-03 14:47:46 -0700953 * find_get_entry - find and get a page cache entry
Randy Dunlap485bb992006-06-23 02:03:49 -0700954 * @mapping: the address_space to search
Johannes Weiner0cd61442014-04-03 14:47:46 -0700955 * @offset: the page cache index
Randy Dunlap485bb992006-06-23 02:03:49 -0700956 *
Johannes Weiner0cd61442014-04-03 14:47:46 -0700957 * Looks up the page cache slot at @mapping & @offset. If there is a
958 * page cache page, it is returned with an increased refcount.
959 *
Johannes Weiner139b6a62014-05-06 12:50:05 -0700960 * If the slot holds a shadow entry of a previously evicted page, or a
961 * swap entry from shmem/tmpfs, it is returned.
Johannes Weiner0cd61442014-04-03 14:47:46 -0700962 *
963 * Otherwise, %NULL is returned.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964 */
Johannes Weiner0cd61442014-04-03 14:47:46 -0700965struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966{
Nick Piggina60637c2008-07-25 19:45:31 -0700967 void **pagep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968 struct page *page;
969
Nick Piggina60637c2008-07-25 19:45:31 -0700970 rcu_read_lock();
971repeat:
972 page = NULL;
973 pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
974 if (pagep) {
975 page = radix_tree_deref_slot(pagep);
Nick Piggin27d20fd2010-11-11 14:05:19 -0800976 if (unlikely(!page))
977 goto out;
Hugh Dickinsa2c16d62011-08-03 16:21:19 -0700978 if (radix_tree_exception(page)) {
Hugh Dickins8079b1c2011-08-03 16:21:28 -0700979 if (radix_tree_deref_retry(page))
980 goto repeat;
981 /*
Johannes Weiner139b6a62014-05-06 12:50:05 -0700982 * A shadow entry of a recently evicted page,
983 * or a swap entry from shmem/tmpfs. Return
984 * it without attempting to raise page count.
Hugh Dickins8079b1c2011-08-03 16:21:28 -0700985 */
986 goto out;
Hugh Dickinsa2c16d62011-08-03 16:21:19 -0700987 }
Nick Piggina60637c2008-07-25 19:45:31 -0700988 if (!page_cache_get_speculative(page))
989 goto repeat;
990
991 /*
992 * Has the page moved?
993 * This is part of the lockless pagecache protocol. See
994 * include/linux/pagemap.h for details.
995 */
996 if (unlikely(page != *pagep)) {
997 page_cache_release(page);
998 goto repeat;
999 }
1000 }
Nick Piggin27d20fd2010-11-11 14:05:19 -08001001out:
Nick Piggina60637c2008-07-25 19:45:31 -07001002 rcu_read_unlock();
1003
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004 return page;
1005}
Johannes Weiner0cd61442014-04-03 14:47:46 -07001006EXPORT_SYMBOL(find_get_entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007
Randy Dunlap485bb992006-06-23 02:03:49 -07001008/**
Johannes Weiner0cd61442014-04-03 14:47:46 -07001009 * find_lock_entry - locate, pin and lock a page cache entry
1010 * @mapping: the address_space to search
1011 * @offset: the page cache index
1012 *
1013 * Looks up the page cache slot at @mapping & @offset. If there is a
1014 * page cache page, it is returned locked and with an increased
1015 * refcount.
1016 *
Johannes Weiner139b6a62014-05-06 12:50:05 -07001017 * If the slot holds a shadow entry of a previously evicted page, or a
1018 * swap entry from shmem/tmpfs, it is returned.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001019 *
1020 * Otherwise, %NULL is returned.
1021 *
1022 * find_lock_entry() may sleep.
1023 */
1024struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025{
1026 struct page *page;
1027
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028repeat:
Johannes Weiner0cd61442014-04-03 14:47:46 -07001029 page = find_get_entry(mapping, offset);
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001030 if (page && !radix_tree_exception(page)) {
Nick Piggina60637c2008-07-25 19:45:31 -07001031 lock_page(page);
1032 /* Has the page been truncated? */
1033 if (unlikely(page->mapping != mapping)) {
1034 unlock_page(page);
1035 page_cache_release(page);
1036 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001037 }
Sasha Levin309381fea2014-01-23 15:52:54 -08001038 VM_BUG_ON_PAGE(page->index != offset, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001040 return page;
1041}
Johannes Weiner0cd61442014-04-03 14:47:46 -07001042EXPORT_SYMBOL(find_lock_entry);
1043
1044/**
Mel Gorman2457aec2014-06-04 16:10:31 -07001045 * pagecache_get_page - find and get a page reference
Johannes Weiner0cd61442014-04-03 14:47:46 -07001046 * @mapping: the address_space to search
1047 * @offset: the page index
Mel Gorman2457aec2014-06-04 16:10:31 -07001048 * @fgp_flags: PCG flags
Randy Dunlap75325182014-07-30 16:08:37 -07001049 * @cache_gfp_mask: gfp mask to use for the page cache data page allocation
1050 * @radix_gfp_mask: gfp mask to use for radix tree node allocation
Johannes Weiner0cd61442014-04-03 14:47:46 -07001051 *
Mel Gorman2457aec2014-06-04 16:10:31 -07001052 * Looks up the page cache slot at @mapping & @offset.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001053 *
Randy Dunlap75325182014-07-30 16:08:37 -07001054 * PCG flags modify how the page is returned.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001055 *
Mel Gorman2457aec2014-06-04 16:10:31 -07001056 * FGP_ACCESSED: the page will be marked accessed
1057 * FGP_LOCK: Page is return locked
1058 * FGP_CREAT: If page is not present then a new page is allocated using
Randy Dunlap75325182014-07-30 16:08:37 -07001059 * @cache_gfp_mask and added to the page cache and the VM's LRU
1060 * list. If radix tree nodes are allocated during page cache
1061 * insertion then @radix_gfp_mask is used. The page is returned
1062 * locked and with an increased refcount. Otherwise, %NULL is
1063 * returned.
Mel Gorman2457aec2014-06-04 16:10:31 -07001064 *
1065 * If FGP_LOCK or FGP_CREAT are specified then the function may sleep even
1066 * if the GFP flags specified for FGP_CREAT are atomic.
1067 *
1068 * If there is a page cache page, it is returned with an increased refcount.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001069 */
Mel Gorman2457aec2014-06-04 16:10:31 -07001070struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
1071 int fgp_flags, gfp_t cache_gfp_mask, gfp_t radix_gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072{
Nick Piggineb2be182007-10-16 01:24:57 -07001073 struct page *page;
Mel Gorman2457aec2014-06-04 16:10:31 -07001074
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075repeat:
Mel Gorman2457aec2014-06-04 16:10:31 -07001076 page = find_get_entry(mapping, offset);
1077 if (radix_tree_exceptional_entry(page))
1078 page = NULL;
1079 if (!page)
1080 goto no_page;
1081
1082 if (fgp_flags & FGP_LOCK) {
1083 if (fgp_flags & FGP_NOWAIT) {
1084 if (!trylock_page(page)) {
1085 page_cache_release(page);
1086 return NULL;
1087 }
1088 } else {
1089 lock_page(page);
1090 }
1091
1092 /* Has the page been truncated? */
1093 if (unlikely(page->mapping != mapping)) {
1094 unlock_page(page);
1095 page_cache_release(page);
1096 goto repeat;
1097 }
1098 VM_BUG_ON_PAGE(page->index != offset, page);
1099 }
1100
1101 if (page && (fgp_flags & FGP_ACCESSED))
1102 mark_page_accessed(page);
1103
1104no_page:
1105 if (!page && (fgp_flags & FGP_CREAT)) {
1106 int err;
1107 if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
1108 cache_gfp_mask |= __GFP_WRITE;
1109 if (fgp_flags & FGP_NOFS) {
1110 cache_gfp_mask &= ~__GFP_FS;
1111 radix_gfp_mask &= ~__GFP_FS;
1112 }
1113
1114 page = __page_cache_alloc(cache_gfp_mask);
Nick Piggineb2be182007-10-16 01:24:57 -07001115 if (!page)
1116 return NULL;
Mel Gorman2457aec2014-06-04 16:10:31 -07001117
1118 if (WARN_ON_ONCE(!(fgp_flags & FGP_LOCK)))
1119 fgp_flags |= FGP_LOCK;
1120
Hugh Dickinseb39d612014-08-06 16:06:43 -07001121 /* Init accessed so avoid atomic mark_page_accessed later */
Mel Gorman2457aec2014-06-04 16:10:31 -07001122 if (fgp_flags & FGP_ACCESSED)
Hugh Dickinseb39d612014-08-06 16:06:43 -07001123 __SetPageReferenced(page);
Mel Gorman2457aec2014-06-04 16:10:31 -07001124
1125 err = add_to_page_cache_lru(page, mapping, offset, radix_gfp_mask);
Nick Piggineb2be182007-10-16 01:24:57 -07001126 if (unlikely(err)) {
1127 page_cache_release(page);
1128 page = NULL;
1129 if (err == -EEXIST)
1130 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 }
Mel Gorman2457aec2014-06-04 16:10:31 -07001133
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 return page;
1135}
Mel Gorman2457aec2014-06-04 16:10:31 -07001136EXPORT_SYMBOL(pagecache_get_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137
1138/**
Johannes Weiner0cd61442014-04-03 14:47:46 -07001139 * find_get_entries - gang pagecache lookup
1140 * @mapping: The address_space to search
1141 * @start: The starting page cache index
1142 * @nr_entries: The maximum number of entries
1143 * @entries: Where the resulting entries are placed
1144 * @indices: The cache indices corresponding to the entries in @entries
1145 *
1146 * find_get_entries() will search for and return a group of up to
1147 * @nr_entries entries in the mapping. The entries are placed at
1148 * @entries. find_get_entries() takes a reference against any actual
1149 * pages it returns.
1150 *
1151 * The search returns a group of mapping-contiguous page cache entries
1152 * with ascending indexes. There may be holes in the indices due to
1153 * not-present pages.
1154 *
Johannes Weiner139b6a62014-05-06 12:50:05 -07001155 * Any shadow entries of evicted pages, or swap entries from
1156 * shmem/tmpfs, are included in the returned array.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001157 *
1158 * find_get_entries() returns the number of pages and shadow entries
1159 * which were found.
1160 */
1161unsigned find_get_entries(struct address_space *mapping,
1162 pgoff_t start, unsigned int nr_entries,
1163 struct page **entries, pgoff_t *indices)
1164{
1165 void **slot;
1166 unsigned int ret = 0;
1167 struct radix_tree_iter iter;
1168
1169 if (!nr_entries)
1170 return 0;
1171
1172 rcu_read_lock();
1173restart:
1174 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
1175 struct page *page;
1176repeat:
1177 page = radix_tree_deref_slot(slot);
1178 if (unlikely(!page))
1179 continue;
1180 if (radix_tree_exception(page)) {
1181 if (radix_tree_deref_retry(page))
1182 goto restart;
1183 /*
Johannes Weiner139b6a62014-05-06 12:50:05 -07001184 * A shadow entry of a recently evicted page,
1185 * or a swap entry from shmem/tmpfs. Return
1186 * it without attempting to raise page count.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001187 */
1188 goto export;
1189 }
1190 if (!page_cache_get_speculative(page))
1191 goto repeat;
1192
1193 /* Has the page moved? */
1194 if (unlikely(page != *slot)) {
1195 page_cache_release(page);
1196 goto repeat;
1197 }
1198export:
1199 indices[ret] = iter.index;
1200 entries[ret] = page;
1201 if (++ret == nr_entries)
1202 break;
1203 }
1204 rcu_read_unlock();
1205 return ret;
1206}
1207
1208/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 * find_get_pages - gang pagecache lookup
1210 * @mapping: The address_space to search
1211 * @start: The starting page index
1212 * @nr_pages: The maximum number of pages
1213 * @pages: Where the resulting pages are placed
1214 *
1215 * find_get_pages() will search for and return a group of up to
1216 * @nr_pages pages in the mapping. The pages are placed at @pages.
1217 * find_get_pages() takes a reference against the returned pages.
1218 *
1219 * The search returns a group of mapping-contiguous pages with ascending
1220 * indexes. There may be holes in the indices due to not-present pages.
1221 *
1222 * find_get_pages() returns the number of pages which were found.
1223 */
1224unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
1225 unsigned int nr_pages, struct page **pages)
1226{
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001227 struct radix_tree_iter iter;
1228 void **slot;
1229 unsigned ret = 0;
1230
1231 if (unlikely(!nr_pages))
1232 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001233
Nick Piggina60637c2008-07-25 19:45:31 -07001234 rcu_read_lock();
1235restart:
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001236 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
Nick Piggina60637c2008-07-25 19:45:31 -07001237 struct page *page;
1238repeat:
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001239 page = radix_tree_deref_slot(slot);
Nick Piggina60637c2008-07-25 19:45:31 -07001240 if (unlikely(!page))
1241 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -07001242
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001243 if (radix_tree_exception(page)) {
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001244 if (radix_tree_deref_retry(page)) {
1245 /*
1246 * Transient condition which can only trigger
1247 * when entry at index 0 moves out of or back
1248 * to root: none yet gotten, safe to restart.
1249 */
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001250 WARN_ON(iter.index);
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001251 goto restart;
1252 }
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001253 /*
Johannes Weiner139b6a62014-05-06 12:50:05 -07001254 * A shadow entry of a recently evicted page,
1255 * or a swap entry from shmem/tmpfs. Skip
1256 * over it.
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001257 */
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001258 continue;
Nick Piggin27d20fd2010-11-11 14:05:19 -08001259 }
Nick Piggina60637c2008-07-25 19:45:31 -07001260
1261 if (!page_cache_get_speculative(page))
1262 goto repeat;
1263
1264 /* Has the page moved? */
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001265 if (unlikely(page != *slot)) {
Nick Piggina60637c2008-07-25 19:45:31 -07001266 page_cache_release(page);
1267 goto repeat;
1268 }
1269
1270 pages[ret] = page;
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001271 if (++ret == nr_pages)
1272 break;
Nick Piggina60637c2008-07-25 19:45:31 -07001273 }
Hugh Dickins5b280c02011-03-22 16:33:07 -07001274
Nick Piggina60637c2008-07-25 19:45:31 -07001275 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276 return ret;
1277}
1278
Jens Axboeebf43502006-04-27 08:46:01 +02001279/**
1280 * find_get_pages_contig - gang contiguous pagecache lookup
1281 * @mapping: The address_space to search
1282 * @index: The starting page index
1283 * @nr_pages: The maximum number of pages
1284 * @pages: Where the resulting pages are placed
1285 *
1286 * find_get_pages_contig() works exactly like find_get_pages(), except
1287 * that the returned number of pages are guaranteed to be contiguous.
1288 *
1289 * find_get_pages_contig() returns the number of pages which were found.
1290 */
1291unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
1292 unsigned int nr_pages, struct page **pages)
1293{
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001294 struct radix_tree_iter iter;
1295 void **slot;
1296 unsigned int ret = 0;
1297
1298 if (unlikely(!nr_pages))
1299 return 0;
Jens Axboeebf43502006-04-27 08:46:01 +02001300
Nick Piggina60637c2008-07-25 19:45:31 -07001301 rcu_read_lock();
1302restart:
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001303 radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
Nick Piggina60637c2008-07-25 19:45:31 -07001304 struct page *page;
1305repeat:
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001306 page = radix_tree_deref_slot(slot);
1307 /* The hole, there no reason to continue */
Nick Piggina60637c2008-07-25 19:45:31 -07001308 if (unlikely(!page))
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001309 break;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -07001310
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001311 if (radix_tree_exception(page)) {
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001312 if (radix_tree_deref_retry(page)) {
1313 /*
1314 * Transient condition which can only trigger
1315 * when entry at index 0 moves out of or back
1316 * to root: none yet gotten, safe to restart.
1317 */
1318 goto restart;
1319 }
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001320 /*
Johannes Weiner139b6a62014-05-06 12:50:05 -07001321 * A shadow entry of a recently evicted page,
1322 * or a swap entry from shmem/tmpfs. Stop
1323 * looking for contiguous pages.
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001324 */
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001325 break;
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001326 }
Nick Piggina60637c2008-07-25 19:45:31 -07001327
Nick Piggina60637c2008-07-25 19:45:31 -07001328 if (!page_cache_get_speculative(page))
1329 goto repeat;
1330
1331 /* Has the page moved? */
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001332 if (unlikely(page != *slot)) {
Nick Piggina60637c2008-07-25 19:45:31 -07001333 page_cache_release(page);
1334 goto repeat;
1335 }
1336
Nick Piggin9cbb4cb2011-01-13 15:45:51 -08001337 /*
1338 * must check mapping and index after taking the ref.
1339 * otherwise we can get both false positives and false
1340 * negatives, which is just confusing to the caller.
1341 */
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001342 if (page->mapping == NULL || page->index != iter.index) {
Nick Piggin9cbb4cb2011-01-13 15:45:51 -08001343 page_cache_release(page);
1344 break;
1345 }
1346
Nick Piggina60637c2008-07-25 19:45:31 -07001347 pages[ret] = page;
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001348 if (++ret == nr_pages)
1349 break;
Jens Axboeebf43502006-04-27 08:46:01 +02001350 }
Nick Piggina60637c2008-07-25 19:45:31 -07001351 rcu_read_unlock();
1352 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +02001353}
David Howellsef71c152007-05-09 02:33:44 -07001354EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +02001355
Randy Dunlap485bb992006-06-23 02:03:49 -07001356/**
1357 * find_get_pages_tag - find and return pages that match @tag
1358 * @mapping: the address_space to search
1359 * @index: the starting page index
1360 * @tag: the tag index
1361 * @nr_pages: the maximum number of pages
1362 * @pages: where the resulting pages are placed
1363 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -07001365 * @tag. We update @index to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001366 */
1367unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
1368 int tag, unsigned int nr_pages, struct page **pages)
1369{
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001370 struct radix_tree_iter iter;
1371 void **slot;
1372 unsigned ret = 0;
1373
1374 if (unlikely(!nr_pages))
1375 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376
Nick Piggina60637c2008-07-25 19:45:31 -07001377 rcu_read_lock();
1378restart:
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001379 radix_tree_for_each_tagged(slot, &mapping->page_tree,
1380 &iter, *index, tag) {
Nick Piggina60637c2008-07-25 19:45:31 -07001381 struct page *page;
1382repeat:
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001383 page = radix_tree_deref_slot(slot);
Nick Piggina60637c2008-07-25 19:45:31 -07001384 if (unlikely(!page))
1385 continue;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -07001386
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001387 if (radix_tree_exception(page)) {
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001388 if (radix_tree_deref_retry(page)) {
1389 /*
1390 * Transient condition which can only trigger
1391 * when entry at index 0 moves out of or back
1392 * to root: none yet gotten, safe to restart.
1393 */
1394 goto restart;
1395 }
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001396 /*
Johannes Weiner139b6a62014-05-06 12:50:05 -07001397 * A shadow entry of a recently evicted page.
1398 *
1399 * Those entries should never be tagged, but
1400 * this tree walk is lockless and the tags are
1401 * looked up in bulk, one radix tree node at a
1402 * time, so there is a sizable window for page
1403 * reclaim to evict a page we saw tagged.
1404 *
1405 * Skip over it.
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001406 */
Johannes Weiner139b6a62014-05-06 12:50:05 -07001407 continue;
Hugh Dickinsa2c16d62011-08-03 16:21:19 -07001408 }
Nick Piggina60637c2008-07-25 19:45:31 -07001409
1410 if (!page_cache_get_speculative(page))
1411 goto repeat;
1412
1413 /* Has the page moved? */
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001414 if (unlikely(page != *slot)) {
Nick Piggina60637c2008-07-25 19:45:31 -07001415 page_cache_release(page);
1416 goto repeat;
1417 }
1418
1419 pages[ret] = page;
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001420 if (++ret == nr_pages)
1421 break;
Nick Piggina60637c2008-07-25 19:45:31 -07001422 }
Hugh Dickins5b280c02011-03-22 16:33:07 -07001423
Nick Piggina60637c2008-07-25 19:45:31 -07001424 rcu_read_unlock();
1425
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426 if (ret)
1427 *index = pages[ret - 1]->index + 1;
Nick Piggina60637c2008-07-25 19:45:31 -07001428
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 return ret;
1430}
David Howellsef71c152007-05-09 02:33:44 -07001431EXPORT_SYMBOL(find_get_pages_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001433/*
1434 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
1435 * a _large_ part of the i/o request. Imagine the worst scenario:
1436 *
1437 * ---R__________________________________________B__________
1438 * ^ reading here ^ bad block(assume 4k)
1439 *
1440 * read(R) => miss => readahead(R...B) => media error => frustrating retries
1441 * => failing the whole request => read(R) => read(R+1) =>
1442 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
1443 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
1444 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
1445 *
1446 * It is going insane. Fix it by quickly scaling down the readahead size.
1447 */
1448static void shrink_readahead_size_eio(struct file *filp,
1449 struct file_ra_state *ra)
1450{
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001451 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07001452}
1453
Randy Dunlap485bb992006-06-23 02:03:49 -07001454/**
Christoph Hellwig36e78912008-02-08 04:21:24 -08001455 * do_generic_file_read - generic file read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001456 * @filp: the file to read
1457 * @ppos: current file position
Al Viro6e58e792014-02-03 17:07:03 -05001458 * @iter: data destination
1459 * @written: already copied
Randy Dunlap485bb992006-06-23 02:03:49 -07001460 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -07001462 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 *
1464 * This is really ugly. But the goto's actually try to clarify some
1465 * of the logic when it comes to error handling etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 */
Al Viro6e58e792014-02-03 17:07:03 -05001467static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
1468 struct iov_iter *iter, ssize_t written)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469{
Christoph Hellwig36e78912008-02-08 04:21:24 -08001470 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 struct inode *inode = mapping->host;
Christoph Hellwig36e78912008-02-08 04:21:24 -08001472 struct file_ra_state *ra = &filp->f_ra;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001473 pgoff_t index;
1474 pgoff_t last_index;
1475 pgoff_t prev_index;
1476 unsigned long offset; /* offset into pagecache page */
Jan Karaec0f1632007-05-06 14:49:25 -07001477 unsigned int prev_offset;
Al Viro6e58e792014-02-03 17:07:03 -05001478 int error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480 index = *ppos >> PAGE_CACHE_SHIFT;
Fengguang Wu7ff81072007-10-16 01:24:35 -07001481 prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
1482 prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
Al Viro6e58e792014-02-03 17:07:03 -05001483 last_index = (*ppos + iter->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 offset = *ppos & ~PAGE_CACHE_MASK;
1485
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 for (;;) {
1487 struct page *page;
Fengguang Wu57f6b962007-10-16 01:24:37 -07001488 pgoff_t end_index;
NeilBrowna32ea1e2007-07-17 04:03:04 -07001489 loff_t isize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 unsigned long nr, ret;
1491
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493find_page:
1494 page = find_get_page(mapping, index);
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001495 if (!page) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001496 page_cache_sync_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001497 ra, filp,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001498 index, last_index - index);
1499 page = find_get_page(mapping, index);
1500 if (unlikely(page == NULL))
1501 goto no_cached_page;
1502 }
1503 if (PageReadahead(page)) {
Rusty Russellcf914a72007-07-19 01:48:08 -07001504 page_cache_async_readahead(mapping,
Fengguang Wu7ff81072007-10-16 01:24:35 -07001505 ra, filp, page,
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07001506 index, last_index - index);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 }
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001508 if (!PageUptodate(page)) {
1509 if (inode->i_blkbits == PAGE_CACHE_SHIFT ||
1510 !mapping->a_ops->is_partially_uptodate)
1511 goto page_not_up_to_date;
Nick Piggin529ae9a2008-08-02 12:01:03 +02001512 if (!trylock_page(page))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001513 goto page_not_up_to_date;
Dave Hansen8d056cb2010-11-11 14:05:15 -08001514 /* Did it get truncated before we got the lock? */
1515 if (!page->mapping)
1516 goto page_not_up_to_date_locked;
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001517 if (!mapping->a_ops->is_partially_uptodate(page,
Al Viro6e58e792014-02-03 17:07:03 -05001518 offset, iter->count))
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001519 goto page_not_up_to_date_locked;
1520 unlock_page(page);
1521 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522page_ok:
NeilBrowna32ea1e2007-07-17 04:03:04 -07001523 /*
1524 * i_size must be checked after we know the page is Uptodate.
1525 *
1526 * Checking i_size after the check allows us to calculate
1527 * the correct value for "nr", which means the zero-filled
1528 * part of the page is not copied back to userspace (unless
1529 * another truncate extends the file - this is desired though).
1530 */
1531
1532 isize = i_size_read(inode);
1533 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1534 if (unlikely(!isize || index > end_index)) {
1535 page_cache_release(page);
1536 goto out;
1537 }
1538
1539 /* nr is the maximum number of bytes to copy from this page */
1540 nr = PAGE_CACHE_SIZE;
1541 if (index == end_index) {
1542 nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1543 if (nr <= offset) {
1544 page_cache_release(page);
1545 goto out;
1546 }
1547 }
1548 nr = nr - offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001549
1550 /* If users can be writing to this page using arbitrary
1551 * virtual addresses, take care about potential aliasing
1552 * before reading the page on the kernel side.
1553 */
1554 if (mapping_writably_mapped(mapping))
1555 flush_dcache_page(page);
1556
1557 /*
Jan Karaec0f1632007-05-06 14:49:25 -07001558 * When a sequential read accesses a page several times,
1559 * only mark it as accessed the first time.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 */
Jan Karaec0f1632007-05-06 14:49:25 -07001561 if (prev_index != index || offset != prev_offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562 mark_page_accessed(page);
1563 prev_index = index;
1564
1565 /*
1566 * Ok, we have the page, and it's up-to-date, so
1567 * now we can copy it to user space...
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 */
Al Viro6e58e792014-02-03 17:07:03 -05001569
1570 ret = copy_page_to_iter(page, offset, nr, iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001571 offset += ret;
1572 index += offset >> PAGE_CACHE_SHIFT;
1573 offset &= ~PAGE_CACHE_MASK;
Jan Kara6ce745e2007-05-06 14:49:26 -07001574 prev_offset = offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001575
1576 page_cache_release(page);
Al Viro6e58e792014-02-03 17:07:03 -05001577 written += ret;
1578 if (!iov_iter_count(iter))
1579 goto out;
1580 if (ret < nr) {
1581 error = -EFAULT;
1582 goto out;
1583 }
1584 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001585
1586page_not_up_to_date:
1587 /* Get exclusive access to the page ... */
Oleg Nesterov85462322008-06-08 21:20:43 +04001588 error = lock_page_killable(page);
1589 if (unlikely(error))
1590 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07001592page_not_up_to_date_locked:
Nick Pigginda6052f2006-09-25 23:31:35 -07001593 /* Did it get truncated before we got the lock? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 if (!page->mapping) {
1595 unlock_page(page);
1596 page_cache_release(page);
1597 continue;
1598 }
1599
1600 /* Did somebody else fill it already? */
1601 if (PageUptodate(page)) {
1602 unlock_page(page);
1603 goto page_ok;
1604 }
1605
1606readpage:
Jeff Moyer91803b42010-05-26 11:49:40 -04001607 /*
1608 * A previous I/O error may have been due to temporary
1609 * failures, eg. multipath errors.
1610 * PG_error will be set again if readpage fails.
1611 */
1612 ClearPageError(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613 /* Start the actual read. The read will unlock the page. */
1614 error = mapping->a_ops->readpage(filp, page);
1615
Zach Brown994fc28c2005-12-15 14:28:17 -08001616 if (unlikely(error)) {
1617 if (error == AOP_TRUNCATED_PAGE) {
1618 page_cache_release(page);
Al Viro6e58e792014-02-03 17:07:03 -05001619 error = 0;
Zach Brown994fc28c2005-12-15 14:28:17 -08001620 goto find_page;
1621 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622 goto readpage_error;
Zach Brown994fc28c2005-12-15 14:28:17 -08001623 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624
1625 if (!PageUptodate(page)) {
Oleg Nesterov85462322008-06-08 21:20:43 +04001626 error = lock_page_killable(page);
1627 if (unlikely(error))
1628 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 if (!PageUptodate(page)) {
1630 if (page->mapping == NULL) {
1631 /*
Christoph Hellwig2ecdc822010-01-26 17:27:20 +01001632 * invalidate_mapping_pages got it
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 */
1634 unlock_page(page);
1635 page_cache_release(page);
1636 goto find_page;
1637 }
1638 unlock_page(page);
Fengguang Wu7ff81072007-10-16 01:24:35 -07001639 shrink_readahead_size_eio(filp, ra);
Oleg Nesterov85462322008-06-08 21:20:43 +04001640 error = -EIO;
1641 goto readpage_error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 }
1643 unlock_page(page);
1644 }
1645
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 goto page_ok;
1647
1648readpage_error:
1649 /* UHHUH! A synchronous read error occurred. Report it */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 page_cache_release(page);
1651 goto out;
1652
1653no_cached_page:
1654 /*
1655 * Ok, it wasn't cached, so we need to create a new
1656 * page..
1657 */
Nick Piggineb2be182007-10-16 01:24:57 -07001658 page = page_cache_alloc_cold(mapping);
1659 if (!page) {
Al Viro6e58e792014-02-03 17:07:03 -05001660 error = -ENOMEM;
Nick Piggineb2be182007-10-16 01:24:57 -07001661 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662 }
Nick Piggineb2be182007-10-16 01:24:57 -07001663 error = add_to_page_cache_lru(page, mapping,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 index, GFP_KERNEL);
1665 if (error) {
Nick Piggineb2be182007-10-16 01:24:57 -07001666 page_cache_release(page);
Al Viro6e58e792014-02-03 17:07:03 -05001667 if (error == -EEXIST) {
1668 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669 goto find_page;
Al Viro6e58e792014-02-03 17:07:03 -05001670 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001671 goto out;
1672 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 goto readpage;
1674 }
1675
1676out:
Fengguang Wu7ff81072007-10-16 01:24:35 -07001677 ra->prev_pos = prev_index;
1678 ra->prev_pos <<= PAGE_CACHE_SHIFT;
1679 ra->prev_pos |= prev_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680
Fengguang Wuf4e6b492007-10-16 01:24:33 -07001681 *ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
Krishna Kumar0c6aa262008-10-15 22:01:13 -07001682 file_accessed(filp);
Al Viro6e58e792014-02-03 17:07:03 -05001683 return written ? written : error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684}
1685
Randy Dunlap485bb992006-06-23 02:03:49 -07001686/**
Al Viro6abd2322014-04-04 14:20:57 -04001687 * generic_file_read_iter - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07001688 * @iocb: kernel I/O control block
Al Viro6abd2322014-04-04 14:20:57 -04001689 * @iter: destination for the data read
Randy Dunlap485bb992006-06-23 02:03:49 -07001690 *
Al Viro6abd2322014-04-04 14:20:57 -04001691 * This is the "read_iter()" routine for all filesystems
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 * that can use the page cache directly.
1693 */
1694ssize_t
Al Viroed978a82014-03-05 22:53:04 -05001695generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696{
Al Viroed978a82014-03-05 22:53:04 -05001697 struct file *file = iocb->ki_filp;
1698 ssize_t retval = 0;
Badari Pulavarty543ade12006-09-30 23:28:48 -07001699 loff_t *ppos = &iocb->ki_pos;
Al Viroed978a82014-03-05 22:53:04 -05001700 loff_t pos = *ppos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701
1702 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
Al Viroed978a82014-03-05 22:53:04 -05001703 if (file->f_flags & O_DIRECT) {
1704 struct address_space *mapping = file->f_mapping;
1705 struct inode *inode = mapping->host;
1706 size_t count = iov_iter_count(iter);
Badari Pulavarty543ade12006-09-30 23:28:48 -07001707 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 if (!count)
1710 goto out; /* skip atime */
1711 size = i_size_read(inode);
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001712 retval = filemap_write_and_wait_range(mapping, pos,
Al Viroed978a82014-03-05 22:53:04 -05001713 pos + count - 1);
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001714 if (!retval) {
Al Viroed978a82014-03-05 22:53:04 -05001715 struct iov_iter data = *iter;
1716 retval = mapping->a_ops->direct_IO(READ, iocb, &data, pos);
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001717 }
Al Viroed978a82014-03-05 22:53:04 -05001718
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001719 if (retval > 0) {
1720 *ppos = pos + retval;
Al Viroed978a82014-03-05 22:53:04 -05001721 iov_iter_advance(iter, retval);
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001722 }
Josef Bacik66f998f2010-05-23 11:00:54 -04001723
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001724 /*
1725 * Btrfs can have a short DIO read if we encounter
1726 * compressed extents, so if there was an error, or if
1727 * we've already read everything we wanted to, or if
1728 * there was a short read because we hit EOF, go ahead
1729 * and return. Otherwise fallthrough to buffered io for
1730 * the rest of the read.
1731 */
Al Viroed978a82014-03-05 22:53:04 -05001732 if (retval < 0 || !iov_iter_count(iter) || *ppos >= size) {
1733 file_accessed(file);
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00001734 goto out;
Steven Whitehouse0e0bcae2006-09-27 14:45:07 -04001735 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 }
1737
Al Viroed978a82014-03-05 22:53:04 -05001738 retval = do_generic_file_read(file, ppos, iter, retval);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739out:
1740 return retval;
1741}
Al Viroed978a82014-03-05 22:53:04 -05001742EXPORT_SYMBOL(generic_file_read_iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744#ifdef CONFIG_MMU
Randy Dunlap485bb992006-06-23 02:03:49 -07001745/**
1746 * page_cache_read - adds requested page to the page cache if not already there
1747 * @file: file to read
1748 * @offset: page index
1749 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 * This adds the requested page to the page cache if it isn't already there,
1751 * and schedules an I/O to read in its contents from disk.
1752 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001753static int page_cache_read(struct file *file, pgoff_t offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754{
1755 struct address_space *mapping = file->f_mapping;
Paul McQuade99dadfd2014-10-09 15:29:03 -07001756 struct page *page;
Zach Brown994fc28c2005-12-15 14:28:17 -08001757 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001758
Zach Brown994fc28c2005-12-15 14:28:17 -08001759 do {
1760 page = page_cache_alloc_cold(mapping);
1761 if (!page)
1762 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763
Zach Brown994fc28c2005-12-15 14:28:17 -08001764 ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
1765 if (ret == 0)
1766 ret = mapping->a_ops->readpage(file, page);
1767 else if (ret == -EEXIST)
1768 ret = 0; /* losing race to add is OK */
1769
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771
Zach Brown994fc28c2005-12-15 14:28:17 -08001772 } while (ret == AOP_TRUNCATED_PAGE);
Paul McQuade99dadfd2014-10-09 15:29:03 -07001773
Zach Brown994fc28c2005-12-15 14:28:17 -08001774 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775}
1776
1777#define MMAP_LOTSAMISS (100)
1778
Linus Torvaldsef00e082009-06-16 15:31:25 -07001779/*
1780 * Synchronous readahead happens when we don't even find
1781 * a page in the page cache at all.
1782 */
1783static void do_sync_mmap_readahead(struct vm_area_struct *vma,
1784 struct file_ra_state *ra,
1785 struct file *file,
1786 pgoff_t offset)
1787{
1788 unsigned long ra_pages;
1789 struct address_space *mapping = file->f_mapping;
1790
1791 /* If we don't want any read-ahead, don't bother */
Joe Perches64363aa2013-07-08 16:00:18 -07001792 if (vma->vm_flags & VM_RAND_READ)
Linus Torvaldsef00e082009-06-16 15:31:25 -07001793 return;
Wu Fengguang275b12b2011-05-24 17:12:28 -07001794 if (!ra->ra_pages)
1795 return;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001796
Joe Perches64363aa2013-07-08 16:00:18 -07001797 if (vma->vm_flags & VM_SEQ_READ) {
Wu Fengguang7ffc59b2009-06-16 15:31:38 -07001798 page_cache_sync_readahead(mapping, ra, file, offset,
1799 ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001800 return;
1801 }
1802
Andi Kleen207d04b2011-05-24 17:12:29 -07001803 /* Avoid banging the cache line if not needed */
1804 if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
Linus Torvaldsef00e082009-06-16 15:31:25 -07001805 ra->mmap_miss++;
1806
1807 /*
1808 * Do we miss much more than hit in this file? If so,
1809 * stop bothering with read-ahead. It will only hurt.
1810 */
1811 if (ra->mmap_miss > MMAP_LOTSAMISS)
1812 return;
1813
Wu Fengguangd30a1102009-06-16 15:31:30 -07001814 /*
1815 * mmap read-around
1816 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001817 ra_pages = max_sane_readahead(ra->ra_pages);
Wu Fengguang275b12b2011-05-24 17:12:28 -07001818 ra->start = max_t(long, 0, offset - ra_pages / 2);
1819 ra->size = ra_pages;
Wu Fengguang2cbea1d2011-05-24 17:12:30 -07001820 ra->async_size = ra_pages / 4;
Wu Fengguang275b12b2011-05-24 17:12:28 -07001821 ra_submit(ra, mapping, file);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001822}
1823
1824/*
1825 * Asynchronous readahead happens when we find the page and PG_readahead,
1826 * so we want to possibly extend the readahead further..
1827 */
1828static void do_async_mmap_readahead(struct vm_area_struct *vma,
1829 struct file_ra_state *ra,
1830 struct file *file,
1831 struct page *page,
1832 pgoff_t offset)
1833{
1834 struct address_space *mapping = file->f_mapping;
1835
1836 /* If we don't want any read-ahead, don't bother */
Joe Perches64363aa2013-07-08 16:00:18 -07001837 if (vma->vm_flags & VM_RAND_READ)
Linus Torvaldsef00e082009-06-16 15:31:25 -07001838 return;
1839 if (ra->mmap_miss > 0)
1840 ra->mmap_miss--;
1841 if (PageReadahead(page))
Wu Fengguang2fad6f52009-06-16 15:31:29 -07001842 page_cache_async_readahead(mapping, ra, file,
1843 page, offset, ra->ra_pages);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001844}
1845
Randy Dunlap485bb992006-06-23 02:03:49 -07001846/**
Nick Piggin54cb8822007-07-19 01:46:59 -07001847 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07001848 * @vma: vma in which the fault was taken
1849 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07001850 *
Nick Piggin54cb8822007-07-19 01:46:59 -07001851 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 * mapped memory region to read in file data during a page fault.
1853 *
1854 * The goto's are kind of ugly, but this streamlines the normal case of having
1855 * it in the page cache, and handles the special cases reasonably without
1856 * having a lot of duplicated code.
Paul Cassella9a95f3c2014-08-06 16:07:24 -07001857 *
1858 * vma->vm_mm->mmap_sem must be held on entry.
1859 *
1860 * If our return value has VM_FAULT_RETRY set, it's because
1861 * lock_page_or_retry() returned 0.
1862 * The mmap_sem has usually been released in this case.
1863 * See __lock_page_or_retry() for the exception.
1864 *
1865 * If our return value does not have VM_FAULT_RETRY set, the mmap_sem
1866 * has not been released.
1867 *
1868 * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869 */
Nick Piggind0217ac2007-07-19 01:47:03 -07001870int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871{
1872 int error;
Nick Piggin54cb8822007-07-19 01:46:59 -07001873 struct file *file = vma->vm_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 struct address_space *mapping = file->f_mapping;
1875 struct file_ra_state *ra = &file->f_ra;
1876 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07001877 pgoff_t offset = vmf->pgoff;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 struct page *page;
Kirill A. Shutemov99e3e532014-04-07 15:37:21 -07001879 loff_t size;
Nick Piggin83c54072007-07-19 01:47:05 -07001880 int ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001881
Kirill A. Shutemov99e3e532014-04-07 15:37:21 -07001882 size = round_up(i_size_read(inode), PAGE_CACHE_SIZE);
1883 if (offset >= size >> PAGE_CACHE_SHIFT)
Linus Torvalds5307cc12007-10-31 09:19:46 -07001884 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886 /*
Johannes Weiner49426422013-10-16 13:46:59 -07001887 * Do we have something in the page cache already?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001888 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001889 page = find_get_page(mapping, offset);
Shaohua Li45cac652012-10-08 16:32:19 -07001890 if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07001892 * We found the page, so try async readahead before
1893 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001895 do_async_mmap_readahead(vma, ra, file, page, offset);
Shaohua Li45cac652012-10-08 16:32:19 -07001896 } else if (!page) {
Linus Torvaldsef00e082009-06-16 15:31:25 -07001897 /* No page in the page cache at all */
1898 do_sync_mmap_readahead(vma, ra, file, offset);
1899 count_vm_event(PGMAJFAULT);
Ying Han456f9982011-05-26 16:25:38 -07001900 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
Linus Torvaldsef00e082009-06-16 15:31:25 -07001901 ret = VM_FAULT_MAJOR;
1902retry_find:
Michel Lespinasseb522c942010-10-26 14:21:56 -07001903 page = find_get_page(mapping, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001904 if (!page)
1905 goto no_cached_page;
1906 }
1907
Michel Lespinassed88c0922010-11-02 13:05:18 -07001908 if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
1909 page_cache_release(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -07001910 return ret | VM_FAULT_RETRY;
Michel Lespinassed88c0922010-11-02 13:05:18 -07001911 }
Michel Lespinasseb522c942010-10-26 14:21:56 -07001912
1913 /* Did it get truncated? */
1914 if (unlikely(page->mapping != mapping)) {
1915 unlock_page(page);
1916 put_page(page);
1917 goto retry_find;
1918 }
Sasha Levin309381fea2014-01-23 15:52:54 -08001919 VM_BUG_ON_PAGE(page->index != offset, page);
Michel Lespinasseb522c942010-10-26 14:21:56 -07001920
Linus Torvalds1da177e2005-04-16 15:20:36 -07001921 /*
Nick Piggind00806b2007-07-19 01:46:57 -07001922 * We have a locked page in the page cache, now we need to check
1923 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001924 */
Nick Piggind00806b2007-07-19 01:46:57 -07001925 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926 goto page_not_uptodate;
1927
Linus Torvaldsef00e082009-06-16 15:31:25 -07001928 /*
1929 * Found the page and have a reference on it.
1930 * We must recheck i_size under page lock.
1931 */
Kirill A. Shutemov99e3e532014-04-07 15:37:21 -07001932 size = round_up(i_size_read(inode), PAGE_CACHE_SIZE);
1933 if (unlikely(offset >= size >> PAGE_CACHE_SHIFT)) {
Nick Piggind00806b2007-07-19 01:46:57 -07001934 unlock_page(page);
Yan Zheng745ad482007-10-08 10:08:37 -07001935 page_cache_release(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07001936 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001937 }
1938
Nick Piggind0217ac2007-07-19 01:47:03 -07001939 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07001940 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942no_cached_page:
1943 /*
1944 * We're only likely to ever get here if MADV_RANDOM is in
1945 * effect.
1946 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07001947 error = page_cache_read(file, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001948
1949 /*
1950 * The page we want has now been added to the page cache.
1951 * In the unlikely event that someone removed it in the
1952 * meantime, we'll just come back here and read it again.
1953 */
1954 if (error >= 0)
1955 goto retry_find;
1956
1957 /*
1958 * An error return from page_cache_read can result if the
1959 * system is low on memory, or a problem occurs while trying
1960 * to schedule I/O.
1961 */
1962 if (error == -ENOMEM)
Nick Piggind0217ac2007-07-19 01:47:03 -07001963 return VM_FAULT_OOM;
1964 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001965
1966page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 /*
1968 * Umm, take care of errors if the page isn't up-to-date.
1969 * Try to re-read it _once_. We do this synchronously,
1970 * because there really aren't any performance issues here
1971 * and we need to check for errors.
1972 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973 ClearPageError(page);
Zach Brown994fc28c2005-12-15 14:28:17 -08001974 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07001975 if (!error) {
1976 wait_on_page_locked(page);
1977 if (!PageUptodate(page))
1978 error = -EIO;
1979 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980 page_cache_release(page);
Nick Piggind00806b2007-07-19 01:46:57 -07001981
1982 if (!error || error == AOP_TRUNCATED_PAGE)
1983 goto retry_find;
1984
1985 /* Things didn't work out. Return zero to tell the mm layer so. */
1986 shrink_readahead_size_eio(file, ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07001987 return VM_FAULT_SIGBUS;
Nick Piggin54cb8822007-07-19 01:46:59 -07001988}
1989EXPORT_SYMBOL(filemap_fault);
1990
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07001991void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
1992{
1993 struct radix_tree_iter iter;
1994 void **slot;
1995 struct file *file = vma->vm_file;
1996 struct address_space *mapping = file->f_mapping;
1997 loff_t size;
1998 struct page *page;
1999 unsigned long address = (unsigned long) vmf->virtual_address;
2000 unsigned long addr;
2001 pte_t *pte;
2002
2003 rcu_read_lock();
2004 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff) {
2005 if (iter.index > vmf->max_pgoff)
2006 break;
2007repeat:
2008 page = radix_tree_deref_slot(slot);
2009 if (unlikely(!page))
2010 goto next;
2011 if (radix_tree_exception(page)) {
2012 if (radix_tree_deref_retry(page))
2013 break;
2014 else
2015 goto next;
2016 }
2017
2018 if (!page_cache_get_speculative(page))
2019 goto repeat;
2020
2021 /* Has the page moved? */
2022 if (unlikely(page != *slot)) {
2023 page_cache_release(page);
2024 goto repeat;
2025 }
2026
2027 if (!PageUptodate(page) ||
2028 PageReadahead(page) ||
2029 PageHWPoison(page))
2030 goto skip;
2031 if (!trylock_page(page))
2032 goto skip;
2033
2034 if (page->mapping != mapping || !PageUptodate(page))
2035 goto unlock;
2036
Kirill A. Shutemov99e3e532014-04-07 15:37:21 -07002037 size = round_up(i_size_read(mapping->host), PAGE_CACHE_SIZE);
2038 if (page->index >= size >> PAGE_CACHE_SHIFT)
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002039 goto unlock;
2040
2041 pte = vmf->pte + page->index - vmf->pgoff;
2042 if (!pte_none(*pte))
2043 goto unlock;
2044
2045 if (file->f_ra.mmap_miss > 0)
2046 file->f_ra.mmap_miss--;
2047 addr = address + (page->index - vmf->pgoff) * PAGE_SIZE;
2048 do_set_pte(vma, addr, page, pte, false, false);
2049 unlock_page(page);
2050 goto next;
2051unlock:
2052 unlock_page(page);
2053skip:
2054 page_cache_release(page);
2055next:
2056 if (iter.index == vmf->max_pgoff)
2057 break;
2058 }
2059 rcu_read_unlock();
2060}
2061EXPORT_SYMBOL(filemap_map_pages);
2062
Jan Kara4fcf1c62012-06-12 16:20:29 +02002063int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
2064{
2065 struct page *page = vmf->page;
Al Viro496ad9a2013-01-23 17:07:38 -05002066 struct inode *inode = file_inode(vma->vm_file);
Jan Kara4fcf1c62012-06-12 16:20:29 +02002067 int ret = VM_FAULT_LOCKED;
2068
Jan Kara14da9202012-06-12 16:20:37 +02002069 sb_start_pagefault(inode->i_sb);
Jan Kara4fcf1c62012-06-12 16:20:29 +02002070 file_update_time(vma->vm_file);
2071 lock_page(page);
2072 if (page->mapping != inode->i_mapping) {
2073 unlock_page(page);
2074 ret = VM_FAULT_NOPAGE;
2075 goto out;
2076 }
Jan Kara14da9202012-06-12 16:20:37 +02002077 /*
2078 * We mark the page dirty already here so that when freeze is in
2079 * progress, we are guaranteed that writeback during freezing will
2080 * see the dirty page and writeprotect it again.
2081 */
2082 set_page_dirty(page);
Darrick J. Wong1d1d1a72013-02-21 16:42:51 -08002083 wait_for_stable_page(page);
Jan Kara4fcf1c62012-06-12 16:20:29 +02002084out:
Jan Kara14da9202012-06-12 16:20:37 +02002085 sb_end_pagefault(inode->i_sb);
Jan Kara4fcf1c62012-06-12 16:20:29 +02002086 return ret;
2087}
2088EXPORT_SYMBOL(filemap_page_mkwrite);
2089
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04002090const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002091 .fault = filemap_fault,
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002092 .map_pages = filemap_map_pages,
Jan Kara4fcf1c62012-06-12 16:20:29 +02002093 .page_mkwrite = filemap_page_mkwrite,
Konstantin Khlebnikov0b173bc2012-10-08 16:28:46 -07002094 .remap_pages = generic_file_remap_pages,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002095};
2096
2097/* This is used for a general mmap of a disk file */
2098
2099int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
2100{
2101 struct address_space *mapping = file->f_mapping;
2102
2103 if (!mapping->a_ops->readpage)
2104 return -ENOEXEC;
2105 file_accessed(file);
2106 vma->vm_ops = &generic_file_vm_ops;
2107 return 0;
2108}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002109
2110/*
2111 * This is for filesystems which do not implement ->writepage.
2112 */
2113int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
2114{
2115 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
2116 return -EINVAL;
2117 return generic_file_mmap(file, vma);
2118}
2119#else
2120int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
2121{
2122 return -ENOSYS;
2123}
2124int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
2125{
2126 return -ENOSYS;
2127}
2128#endif /* CONFIG_MMU */
2129
2130EXPORT_SYMBOL(generic_file_mmap);
2131EXPORT_SYMBOL(generic_file_readonly_mmap);
2132
Sasha Levin67f9fd92014-04-03 14:48:18 -07002133static struct page *wait_on_page_read(struct page *page)
2134{
2135 if (!IS_ERR(page)) {
2136 wait_on_page_locked(page);
2137 if (!PageUptodate(page)) {
2138 page_cache_release(page);
2139 page = ERR_PTR(-EIO);
2140 }
2141 }
2142 return page;
2143}
2144
Nick Piggin6fe69002007-05-06 14:49:04 -07002145static struct page *__read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07002146 pgoff_t index,
Hugh Dickins5e5358e2011-07-25 17:12:23 -07002147 int (*filler)(void *, struct page *),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002148 void *data,
2149 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002150{
Nick Piggineb2be182007-10-16 01:24:57 -07002151 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152 int err;
2153repeat:
2154 page = find_get_page(mapping, index);
2155 if (!page) {
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002156 page = __page_cache_alloc(gfp | __GFP_COLD);
Nick Piggineb2be182007-10-16 01:24:57 -07002157 if (!page)
2158 return ERR_PTR(-ENOMEM);
Dave Kleikampe6f67b82011-12-21 11:05:48 -06002159 err = add_to_page_cache_lru(page, mapping, index, gfp);
Nick Piggineb2be182007-10-16 01:24:57 -07002160 if (unlikely(err)) {
2161 page_cache_release(page);
2162 if (err == -EEXIST)
2163 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002164 /* Presumably ENOMEM for radix tree node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 return ERR_PTR(err);
2166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 err = filler(data, page);
2168 if (err < 0) {
2169 page_cache_release(page);
2170 page = ERR_PTR(err);
Sasha Levin67f9fd92014-04-03 14:48:18 -07002171 } else {
2172 page = wait_on_page_read(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173 }
2174 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175 return page;
2176}
2177
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002178static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07002179 pgoff_t index,
Hugh Dickins5e5358e2011-07-25 17:12:23 -07002180 int (*filler)(void *, struct page *),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002181 void *data,
2182 gfp_t gfp)
2183
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184{
2185 struct page *page;
2186 int err;
2187
2188retry:
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002189 page = __read_cache_page(mapping, index, filler, data, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002190 if (IS_ERR(page))
David Howellsc855ff32007-05-09 13:42:20 +01002191 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 if (PageUptodate(page))
2193 goto out;
2194
2195 lock_page(page);
2196 if (!page->mapping) {
2197 unlock_page(page);
2198 page_cache_release(page);
2199 goto retry;
2200 }
2201 if (PageUptodate(page)) {
2202 unlock_page(page);
2203 goto out;
2204 }
2205 err = filler(data, page);
2206 if (err < 0) {
2207 page_cache_release(page);
David Howellsc855ff32007-05-09 13:42:20 +01002208 return ERR_PTR(err);
Sasha Levin67f9fd92014-04-03 14:48:18 -07002209 } else {
2210 page = wait_on_page_read(page);
2211 if (IS_ERR(page))
2212 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213 }
David Howellsc855ff32007-05-09 13:42:20 +01002214out:
Nick Piggin6fe69002007-05-06 14:49:04 -07002215 mark_page_accessed(page);
2216 return page;
2217}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002218
2219/**
Sasha Levin67f9fd92014-04-03 14:48:18 -07002220 * read_cache_page - read into page cache, fill it if needed
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002221 * @mapping: the page's address_space
2222 * @index: the page index
2223 * @filler: function to perform the read
Hugh Dickins5e5358e2011-07-25 17:12:23 -07002224 * @data: first arg to filler(data, page) function, often left as NULL
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002225 *
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002226 * Read into the page cache. If a page already exists, and PageUptodate() is
Sasha Levin67f9fd92014-04-03 14:48:18 -07002227 * not set, try to fill the page and wait for it to become unlocked.
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002228 *
2229 * If the page does not get brought uptodate, return -EIO.
2230 */
Sasha Levin67f9fd92014-04-03 14:48:18 -07002231struct page *read_cache_page(struct address_space *mapping,
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002232 pgoff_t index,
Hugh Dickins5e5358e2011-07-25 17:12:23 -07002233 int (*filler)(void *, struct page *),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002234 void *data)
2235{
2236 return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
2237}
Sasha Levin67f9fd92014-04-03 14:48:18 -07002238EXPORT_SYMBOL(read_cache_page);
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002239
2240/**
2241 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
2242 * @mapping: the page's address_space
2243 * @index: the page index
2244 * @gfp: the page allocator flags to use if allocating
2245 *
2246 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
Dave Kleikampe6f67b82011-12-21 11:05:48 -06002247 * any new page allocations done using the specified allocation flags.
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002248 *
2249 * If the page does not get brought uptodate, return -EIO.
2250 */
2251struct page *read_cache_page_gfp(struct address_space *mapping,
2252 pgoff_t index,
2253 gfp_t gfp)
2254{
2255 filler_t *filler = (filler_t *)mapping->a_ops->readpage;
2256
Sasha Levin67f9fd92014-04-03 14:48:18 -07002257 return do_read_cache_page(mapping, index, filler, NULL, gfp);
Linus Torvalds0531b2a2010-01-27 09:20:03 -08002258}
2259EXPORT_SYMBOL(read_cache_page_gfp);
2260
Nick Piggin2f718ff2007-10-16 01:24:59 -07002261/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 * Performs necessary checks before doing a write
2263 *
Randy Dunlap485bb992006-06-23 02:03:49 -07002264 * Can adjust writing position or amount of bytes to write.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002265 * Returns appropriate error code that caller should return or
2266 * zero in case that write should be allowed.
2267 */
2268inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
2269{
2270 struct inode *inode = file->f_mapping->host;
Jiri Slaby59e99e52010-03-05 13:41:44 -08002271 unsigned long limit = rlimit(RLIMIT_FSIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272
2273 if (unlikely(*pos < 0))
2274 return -EINVAL;
2275
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276 if (!isblk) {
2277 /* FIXME: this is for backwards compatibility with 2.4 */
2278 if (file->f_flags & O_APPEND)
2279 *pos = i_size_read(inode);
2280
2281 if (limit != RLIM_INFINITY) {
2282 if (*pos >= limit) {
2283 send_sig(SIGXFSZ, current, 0);
2284 return -EFBIG;
2285 }
2286 if (*count > limit - (typeof(limit))*pos) {
2287 *count = limit - (typeof(limit))*pos;
2288 }
2289 }
2290 }
2291
2292 /*
2293 * LFS rule
2294 */
2295 if (unlikely(*pos + *count > MAX_NON_LFS &&
2296 !(file->f_flags & O_LARGEFILE))) {
2297 if (*pos >= MAX_NON_LFS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002298 return -EFBIG;
2299 }
2300 if (*count > MAX_NON_LFS - (unsigned long)*pos) {
2301 *count = MAX_NON_LFS - (unsigned long)*pos;
2302 }
2303 }
2304
2305 /*
2306 * Are we about to exceed the fs block limit ?
2307 *
2308 * If we have written data it becomes a short write. If we have
2309 * exceeded without writing data we send a signal and return EFBIG.
2310 * Linus frestrict idea will clean these up nicely..
2311 */
2312 if (likely(!isblk)) {
2313 if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
2314 if (*count || *pos > inode->i_sb->s_maxbytes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002315 return -EFBIG;
2316 }
2317 /* zero-length writes at ->s_maxbytes are OK */
2318 }
2319
2320 if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
2321 *count = inode->i_sb->s_maxbytes - *pos;
2322 } else {
David Howells93614012006-09-30 20:45:40 +02002323#ifdef CONFIG_BLOCK
Linus Torvalds1da177e2005-04-16 15:20:36 -07002324 loff_t isize;
2325 if (bdev_read_only(I_BDEV(inode)))
2326 return -EPERM;
2327 isize = i_size_read(inode);
2328 if (*pos >= isize) {
2329 if (*count || *pos > isize)
2330 return -ENOSPC;
2331 }
2332
2333 if (*pos + *count > isize)
2334 *count = isize - *pos;
David Howells93614012006-09-30 20:45:40 +02002335#else
2336 return -EPERM;
2337#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 }
2339 return 0;
2340}
2341EXPORT_SYMBOL(generic_write_checks);
2342
Nick Pigginafddba42007-10-16 01:25:01 -07002343int pagecache_write_begin(struct file *file, struct address_space *mapping,
2344 loff_t pos, unsigned len, unsigned flags,
2345 struct page **pagep, void **fsdata)
2346{
2347 const struct address_space_operations *aops = mapping->a_ops;
2348
Nick Piggin4e02ed42008-10-29 14:00:55 -07002349 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002350 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002351}
2352EXPORT_SYMBOL(pagecache_write_begin);
2353
2354int pagecache_write_end(struct file *file, struct address_space *mapping,
2355 loff_t pos, unsigned len, unsigned copied,
2356 struct page *page, void *fsdata)
2357{
2358 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07002359
Nick Piggin4e02ed42008-10-29 14:00:55 -07002360 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07002361}
2362EXPORT_SYMBOL(pagecache_write_end);
2363
Linus Torvalds1da177e2005-04-16 15:20:36 -07002364ssize_t
Al Viro0c949332014-03-22 06:51:37 -04002365generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002366{
2367 struct file *file = iocb->ki_filp;
2368 struct address_space *mapping = file->f_mapping;
2369 struct inode *inode = mapping->host;
2370 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002371 size_t write_len;
2372 pgoff_t end;
Al Viro26978b82014-03-10 14:08:45 -04002373 struct iov_iter data;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374
Al Viro0c949332014-03-22 06:51:37 -04002375 write_len = iov_iter_count(from);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002376 end = (pos + write_len - 1) >> PAGE_CACHE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002377
Nick Piggin48b47c52009-01-06 14:40:22 -08002378 written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002379 if (written)
2380 goto out;
2381
2382 /*
2383 * After a write we want buffered reads to be sure to go to disk to get
2384 * the new data. We invalidate clean cached page from the region we're
2385 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002386 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07002387 */
2388 if (mapping->nrpages) {
2389 written = invalidate_inode_pages2_range(mapping,
2390 pos >> PAGE_CACHE_SHIFT, end);
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002391 /*
2392 * If a page can not be invalidated, return 0 to fall back
2393 * to buffered write.
2394 */
2395 if (written) {
2396 if (written == -EBUSY)
2397 return 0;
Christoph Hellwiga969e902008-07-23 21:27:04 -07002398 goto out;
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07002399 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002400 }
2401
Al Viro26978b82014-03-10 14:08:45 -04002402 data = *from;
2403 written = mapping->a_ops->direct_IO(WRITE, iocb, &data, pos);
Christoph Hellwiga969e902008-07-23 21:27:04 -07002404
2405 /*
2406 * Finally, try again to invalidate clean pages which might have been
2407 * cached by non-direct readahead, or faulted in by get_user_pages()
2408 * if the source of the write was an mmap'ed region of the file
2409 * we're writing. Either one is a pretty crazy thing to do,
2410 * so we don't support it 100%. If this invalidation
2411 * fails, tough, the write still worked...
2412 */
2413 if (mapping->nrpages) {
2414 invalidate_inode_pages2_range(mapping,
2415 pos >> PAGE_CACHE_SHIFT, end);
2416 }
2417
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418 if (written > 0) {
Namhyung Kim01166512010-10-26 14:21:58 -07002419 pos += written;
Al Virof8579f82014-03-03 22:03:20 -05002420 iov_iter_advance(from, written);
Namhyung Kim01166512010-10-26 14:21:58 -07002421 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
2422 i_size_write(inode, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423 mark_inode_dirty(inode);
2424 }
Al Viro5cb6c6c2014-02-11 20:58:20 -05002425 iocb->ki_pos = pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07002427out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002428 return written;
2429}
2430EXPORT_SYMBOL(generic_file_direct_write);
2431
Nick Piggineb2be182007-10-16 01:24:57 -07002432/*
2433 * Find or create a page at the given pagecache position. Return the locked
2434 * page. This function is specifically for buffered writes.
2435 */
Nick Piggin54566b22009-01-04 12:00:53 -08002436struct page *grab_cache_page_write_begin(struct address_space *mapping,
2437 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07002438{
Nick Piggineb2be182007-10-16 01:24:57 -07002439 struct page *page;
Mel Gorman2457aec2014-06-04 16:10:31 -07002440 int fgp_flags = FGP_LOCK|FGP_ACCESSED|FGP_WRITE|FGP_CREAT;
Johannes Weiner0faa70c2012-01-10 15:07:53 -08002441
Nick Piggin54566b22009-01-04 12:00:53 -08002442 if (flags & AOP_FLAG_NOFS)
Mel Gorman2457aec2014-06-04 16:10:31 -07002443 fgp_flags |= FGP_NOFS;
Nick Piggineb2be182007-10-16 01:24:57 -07002444
Mel Gorman2457aec2014-06-04 16:10:31 -07002445 page = pagecache_get_page(mapping, index, fgp_flags,
2446 mapping_gfp_mask(mapping),
2447 GFP_KERNEL);
2448 if (page)
2449 wait_for_stable_page(page);
2450
Nick Piggineb2be182007-10-16 01:24:57 -07002451 return page;
2452}
Nick Piggin54566b22009-01-04 12:00:53 -08002453EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07002454
Al Viro3b93f912014-02-11 21:34:08 -05002455ssize_t generic_perform_write(struct file *file,
Nick Pigginafddba42007-10-16 01:25:01 -07002456 struct iov_iter *i, loff_t pos)
2457{
2458 struct address_space *mapping = file->f_mapping;
2459 const struct address_space_operations *a_ops = mapping->a_ops;
2460 long status = 0;
2461 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07002462 unsigned int flags = 0;
2463
2464 /*
2465 * Copies from kernel address space cannot fail (NFSD is a big user).
2466 */
2467 if (segment_eq(get_fs(), KERNEL_DS))
2468 flags |= AOP_FLAG_UNINTERRUPTIBLE;
Nick Pigginafddba42007-10-16 01:25:01 -07002469
2470 do {
2471 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07002472 unsigned long offset; /* Offset into pagecache page */
2473 unsigned long bytes; /* Bytes to write to page */
2474 size_t copied; /* Bytes copied from user */
2475 void *fsdata;
2476
2477 offset = (pos & (PAGE_CACHE_SIZE - 1));
Nick Pigginafddba42007-10-16 01:25:01 -07002478 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2479 iov_iter_count(i));
2480
2481again:
Nick Pigginafddba42007-10-16 01:25:01 -07002482 /*
2483 * Bring in the user page that we will copy from _first_.
2484 * Otherwise there's a nasty deadlock on copying from the
2485 * same page as we're writing to, without it being marked
2486 * up-to-date.
2487 *
2488 * Not only is this an optimisation, but it is also required
2489 * to check that the address is actually valid, when atomic
2490 * usercopies are used, below.
2491 */
2492 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
2493 status = -EFAULT;
2494 break;
2495 }
2496
Nick Piggin674b8922007-10-16 01:25:03 -07002497 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07002498 &page, &fsdata);
Mel Gorman2457aec2014-06-04 16:10:31 -07002499 if (unlikely(status < 0))
Nick Pigginafddba42007-10-16 01:25:01 -07002500 break;
2501
anfei zhou931e80e2010-02-02 13:44:02 -08002502 if (mapping_writably_mapped(mapping))
2503 flush_dcache_page(page);
2504
Nick Pigginafddba42007-10-16 01:25:01 -07002505 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
Nick Pigginafddba42007-10-16 01:25:01 -07002506 flush_dcache_page(page);
2507
2508 status = a_ops->write_end(file, mapping, pos, bytes, copied,
2509 page, fsdata);
2510 if (unlikely(status < 0))
2511 break;
2512 copied = status;
2513
2514 cond_resched();
2515
Nick Piggin124d3b72008-02-02 15:01:17 +01002516 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07002517 if (unlikely(copied == 0)) {
2518 /*
2519 * If we were unable to copy any data at all, we must
2520 * fall back to a single segment length write.
2521 *
2522 * If we didn't fallback here, we could livelock
2523 * because not all segments in the iov can be copied at
2524 * once without a pagefault.
2525 */
2526 bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
2527 iov_iter_single_seg_count(i));
2528 goto again;
2529 }
Nick Pigginafddba42007-10-16 01:25:01 -07002530 pos += copied;
2531 written += copied;
2532
2533 balance_dirty_pages_ratelimited(mapping);
Jan Karaa50527b2011-12-02 09:17:02 +08002534 if (fatal_signal_pending(current)) {
2535 status = -EINTR;
2536 break;
2537 }
Nick Pigginafddba42007-10-16 01:25:01 -07002538 } while (iov_iter_count(i));
2539
2540 return written ? written : status;
2541}
Al Viro3b93f912014-02-11 21:34:08 -05002542EXPORT_SYMBOL(generic_perform_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002543
Jan Karae4dd9de2009-08-17 18:10:06 +02002544/**
Al Viro81742022014-04-03 03:17:43 -04002545 * __generic_file_write_iter - write data to a file
Jan Karae4dd9de2009-08-17 18:10:06 +02002546 * @iocb: IO state structure (file, offset, etc.)
Al Viro81742022014-04-03 03:17:43 -04002547 * @from: iov_iter with data to write
Jan Karae4dd9de2009-08-17 18:10:06 +02002548 *
2549 * This function does all the work needed for actually writing data to a
2550 * file. It does all basic checks, removes SUID from the file, updates
2551 * modification times and calls proper subroutines depending on whether we
2552 * do direct IO or a standard buffered write.
2553 *
2554 * It expects i_mutex to be grabbed unless we work on a block device or similar
2555 * object which does not need locking at all.
2556 *
2557 * This function does *not* take care of syncing data in case of O_SYNC write.
2558 * A caller has to handle it. This is mainly due to the fact that we want to
2559 * avoid syncing under i_mutex.
2560 */
Al Viro81742022014-04-03 03:17:43 -04002561ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562{
2563 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002564 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002565 struct inode *inode = mapping->host;
Al Viro41fc56d2014-02-09 12:58:52 -05002566 loff_t pos = iocb->ki_pos;
Al Viro3b93f912014-02-11 21:34:08 -05002567 ssize_t written = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 ssize_t err;
Al Viro3b93f912014-02-11 21:34:08 -05002569 ssize_t status;
Al Viro81742022014-04-03 03:17:43 -04002570 size_t count = iov_iter_count(from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571
Linus Torvalds1da177e2005-04-16 15:20:36 -07002572 /* We can write back this queue in page reclaim */
2573 current->backing_dev_info = mapping->backing_dev_info;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
2575 if (err)
2576 goto out;
2577
2578 if (count == 0)
2579 goto out;
2580
Al Viro81742022014-04-03 03:17:43 -04002581 iov_iter_truncate(from, count);
Al Viro0c949332014-03-22 06:51:37 -04002582
Miklos Szeredi2f1936b2008-06-24 16:50:14 +02002583 err = file_remove_suid(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002584 if (err)
2585 goto out;
2586
Josef Bacikc3b2da32012-03-26 09:59:21 -04002587 err = file_update_time(file);
2588 if (err)
2589 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002590
2591 /* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
2592 if (unlikely(file->f_flags & O_DIRECT)) {
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002593 loff_t endbyte;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002594
Al Viro81742022014-04-03 03:17:43 -04002595 written = generic_file_direct_write(iocb, from, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002596 if (written < 0 || written == count)
2597 goto out;
Al Viro3b93f912014-02-11 21:34:08 -05002598
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 /*
2600 * direct-io write to a hole: fall through to buffered I/O
2601 * for completing the rest of the request.
2602 */
2603 pos += written;
2604 count -= written;
Al Viro3b93f912014-02-11 21:34:08 -05002605
Al Viro81742022014-04-03 03:17:43 -04002606 status = generic_perform_write(file, from, pos);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002607 /*
Al Viro3b93f912014-02-11 21:34:08 -05002608 * If generic_perform_write() returned a synchronous error
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002609 * then we want to return the number of bytes which were
2610 * direct-written, or the error code if that was zero. Note
2611 * that this differs from normal direct-io semantics, which
2612 * will return -EFOO even if some bytes were written.
2613 */
Al Viro60bb4522014-08-08 12:39:16 -04002614 if (unlikely(status < 0)) {
Al Viro3b93f912014-02-11 21:34:08 -05002615 err = status;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002616 goto out;
2617 }
Al Viro3b93f912014-02-11 21:34:08 -05002618 iocb->ki_pos = pos + status;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002619 /*
2620 * We need to ensure that the page cache pages are written to
2621 * disk and invalidated to preserve the expected O_DIRECT
2622 * semantics.
2623 */
Al Viro3b93f912014-02-11 21:34:08 -05002624 endbyte = pos + status - 1;
Christoph Hellwigc05c4ed2009-09-23 15:07:30 +02002625 err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002626 if (err == 0) {
Al Viro3b93f912014-02-11 21:34:08 -05002627 written += status;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002628 invalidate_mapping_pages(mapping,
2629 pos >> PAGE_CACHE_SHIFT,
2630 endbyte >> PAGE_CACHE_SHIFT);
2631 } else {
2632 /*
2633 * We don't know how much we wrote, so just return
2634 * the number of bytes which were direct-written
2635 */
2636 }
2637 } else {
Al Viro81742022014-04-03 03:17:43 -04002638 written = generic_perform_write(file, from, pos);
Al Viro3b93f912014-02-11 21:34:08 -05002639 if (likely(written >= 0))
2640 iocb->ki_pos = pos + written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07002641 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642out:
2643 current->backing_dev_info = NULL;
2644 return written ? written : err;
2645}
Al Viro81742022014-04-03 03:17:43 -04002646EXPORT_SYMBOL(__generic_file_write_iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647
Jan Karae4dd9de2009-08-17 18:10:06 +02002648/**
Al Viro81742022014-04-03 03:17:43 -04002649 * generic_file_write_iter - write data to a file
Jan Karae4dd9de2009-08-17 18:10:06 +02002650 * @iocb: IO state structure
Al Viro81742022014-04-03 03:17:43 -04002651 * @from: iov_iter with data to write
Jan Karae4dd9de2009-08-17 18:10:06 +02002652 *
Al Viro81742022014-04-03 03:17:43 -04002653 * This is a wrapper around __generic_file_write_iter() to be used by most
Jan Karae4dd9de2009-08-17 18:10:06 +02002654 * filesystems. It takes care of syncing the file in case of O_SYNC file
2655 * and acquires i_mutex as needed.
2656 */
Al Viro81742022014-04-03 03:17:43 -04002657ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002658{
2659 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02002660 struct inode *inode = file->f_mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002661 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002662
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002663 mutex_lock(&inode->i_mutex);
Al Viro81742022014-04-03 03:17:43 -04002664 ret = __generic_file_write_iter(iocb, from);
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002665 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002666
Christoph Hellwig02afc272013-09-04 15:04:40 +02002667 if (ret > 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668 ssize_t err;
2669
Al Virod311d792014-02-09 15:18:09 -05002670 err = generic_write_sync(file, iocb->ki_pos - ret, ret);
2671 if (err < 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002672 ret = err;
2673 }
2674 return ret;
2675}
Al Viro81742022014-04-03 03:17:43 -04002676EXPORT_SYMBOL(generic_file_write_iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677
David Howellscf9a2ae2006-08-29 19:05:54 +01002678/**
2679 * try_to_release_page() - release old fs-specific metadata on a page
2680 *
2681 * @page: the page which the kernel is trying to free
2682 * @gfp_mask: memory allocation flags (and I/O mode)
2683 *
2684 * The address_space is to try to release any data against the page
2685 * (presumably at page->private). If the release was successful, return `1'.
2686 * Otherwise return zero.
2687 *
David Howells266cf652009-04-03 16:42:36 +01002688 * This may also be called if PG_fscache is set on a page, indicating that the
2689 * page is known to the local caching routines.
2690 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002691 * The @gfp_mask argument specifies whether I/O may be performed to release
Mingming Cao3f31fdd2008-07-25 01:46:22 -07002692 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01002693 *
David Howellscf9a2ae2006-08-29 19:05:54 +01002694 */
2695int try_to_release_page(struct page *page, gfp_t gfp_mask)
2696{
2697 struct address_space * const mapping = page->mapping;
2698
2699 BUG_ON(!PageLocked(page));
2700 if (PageWriteback(page))
2701 return 0;
2702
2703 if (mapping && mapping->a_ops->releasepage)
2704 return mapping->a_ops->releasepage(page, gfp_mask);
2705 return try_to_free_buffers(page);
2706}
2707
2708EXPORT_SYMBOL(try_to_release_page);