blob: c7a5602d01eed200912d3a90ca4ac6780209cb6f [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/buffer.c
3 *
4 * Copyright (C) 1991, 1992, 2002 Linus Torvalds
5 */
6
7/*
8 * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
9 *
10 * Removed a lot of unnecessary code and simplified things now that
11 * the buffer cache isn't our primary cache - Andrew Tridgell 12/96
12 *
13 * Speed up hash, lru, and free list operations. Use gfp() for allocating
14 * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM
15 *
16 * Added 32k buffer block sizes - these are required older ARM systems. - RMK
17 *
18 * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
19 */
20
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/kernel.h>
22#include <linux/syscalls.h>
23#include <linux/fs.h>
24#include <linux/mm.h>
25#include <linux/percpu.h>
26#include <linux/slab.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080027#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/blkdev.h>
29#include <linux/file.h>
30#include <linux/quotaops.h>
31#include <linux/highmem.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050032#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033#include <linux/writeback.h>
34#include <linux/hash.h>
35#include <linux/suspend.h>
36#include <linux/buffer_head.h>
Andrew Morton55e829a2006-12-10 02:19:27 -080037#include <linux/task_io_accounting_ops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038#include <linux/bio.h>
39#include <linux/notifier.h>
40#include <linux/cpu.h>
41#include <linux/bitops.h>
42#include <linux/mpage.h>
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070043#include <linux/bit_spinlock.h>
Tejun Heo5305cb82013-01-11 13:06:36 -080044#include <trace/events/block.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
49
Yan Honga3f3c292012-12-12 13:52:15 -080050void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
Linus Torvalds1da177e2005-04-16 15:20:36 -070051{
52 bh->b_end_io = handler;
53 bh->b_private = private;
54}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070055EXPORT_SYMBOL(init_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
Tejun Heof0059af2013-01-11 13:06:35 -080057inline void touch_buffer(struct buffer_head *bh)
58{
Tejun Heo5305cb82013-01-11 13:06:36 -080059 trace_block_touch_buffer(bh);
Tejun Heof0059af2013-01-11 13:06:35 -080060 mark_page_accessed(bh->b_page);
61}
62EXPORT_SYMBOL(touch_buffer);
63
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080064void __lock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070065{
NeilBrown74316202014-07-07 15:16:04 +100066 wait_on_bit_lock_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067}
68EXPORT_SYMBOL(__lock_buffer);
69
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080070void unlock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071{
Nick Piggin51b07fc2008-10-18 20:27:00 -070072 clear_bit_unlock(BH_Lock, &bh->b_state);
Peter Zijlstra4e857c52014-03-17 18:06:10 +010073 smp_mb__after_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 wake_up_bit(&bh->b_state, BH_Lock);
75}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070076EXPORT_SYMBOL(unlock_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
78/*
Mel Gormanb4597222013-07-03 15:02:05 -070079 * Returns if the page has dirty or writeback buffers. If all the buffers
80 * are unlocked and clean then the PageDirty information is stale. If
81 * any of the pages are locked, it is assumed they are locked for IO.
82 */
83void buffer_check_dirty_writeback(struct page *page,
84 bool *dirty, bool *writeback)
85{
86 struct buffer_head *head, *bh;
87 *dirty = false;
88 *writeback = false;
89
90 BUG_ON(!PageLocked(page));
91
92 if (!page_has_buffers(page))
93 return;
94
95 if (PageWriteback(page))
96 *writeback = true;
97
98 head = page_buffers(page);
99 bh = head;
100 do {
101 if (buffer_locked(bh))
102 *writeback = true;
103
104 if (buffer_dirty(bh))
105 *dirty = true;
106
107 bh = bh->b_this_page;
108 } while (bh != head);
109}
110EXPORT_SYMBOL(buffer_check_dirty_writeback);
111
112/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 * Block until a buffer comes unlocked. This doesn't stop it
114 * from becoming locked again - you have to lock it yourself
115 * if you want to preserve its state.
116 */
117void __wait_on_buffer(struct buffer_head * bh)
118{
NeilBrown74316202014-07-07 15:16:04 +1000119 wait_on_bit_io(&bh->b_state, BH_Lock, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700121EXPORT_SYMBOL(__wait_on_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122
123static void
124__clear_page_buffers(struct page *page)
125{
126 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700127 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 page_cache_release(page);
129}
130
Robert Elliottb744c2a2014-10-21 13:55:09 -0600131static void buffer_io_error(struct buffer_head *bh, char *msg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132{
133 char b[BDEVNAME_SIZE];
Robert Elliott432f16e2014-10-21 13:55:11 -0600134
135 if (!test_bit(BH_Quiet, &bh->b_state))
136 printk_ratelimited(KERN_ERR
137 "Buffer I/O error on dev %s, logical block %llu%s\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138 bdevname(bh->b_bdev, b),
Robert Elliottb744c2a2014-10-21 13:55:09 -0600139 (unsigned long long)bh->b_blocknr, msg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140}
141
142/*
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700143 * End-of-IO handler helper function which does not touch the bh after
144 * unlocking it.
145 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
146 * a race there is benign: unlock_buffer() only use the bh's address for
147 * hashing after unlocking the buffer, so it doesn't actually touch the bh
148 * itself.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 */
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700150static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151{
152 if (uptodate) {
153 set_buffer_uptodate(bh);
154 } else {
155 /* This happens, due to failed READA attempts. */
156 clear_buffer_uptodate(bh);
157 }
158 unlock_buffer(bh);
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700159}
160
161/*
162 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
163 * unlock the buffer. This is what ll_rw_block uses too.
164 */
165void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
166{
167 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 put_bh(bh);
169}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700170EXPORT_SYMBOL(end_buffer_read_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171
172void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
173{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 if (uptodate) {
175 set_buffer_uptodate(bh);
176 } else {
Robert Elliott432f16e2014-10-21 13:55:11 -0600177 buffer_io_error(bh, ", lost sync page write");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 set_buffer_write_io_error(bh);
179 clear_buffer_uptodate(bh);
180 }
181 unlock_buffer(bh);
182 put_bh(bh);
183}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700184EXPORT_SYMBOL(end_buffer_write_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185
186/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 * Various filesystems appear to want __find_get_block to be non-blocking.
188 * But it's the page lock which protects the buffers. To get around this,
189 * we get exclusion from try_to_free_buffers with the blockdev mapping's
190 * private_lock.
191 *
192 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
193 * may be quite high. This code could TryLock the page, and if that
194 * succeeds, there is no need to take private_lock. (But if
195 * private_lock is contended then so is mapping->tree_lock).
196 */
197static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800198__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199{
200 struct inode *bd_inode = bdev->bd_inode;
201 struct address_space *bd_mapping = bd_inode->i_mapping;
202 struct buffer_head *ret = NULL;
203 pgoff_t index;
204 struct buffer_head *bh;
205 struct buffer_head *head;
206 struct page *page;
207 int all_mapped = 1;
208
209 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
Mel Gorman2457aec2014-06-04 16:10:31 -0700210 page = find_get_page_flags(bd_mapping, index, FGP_ACCESSED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 if (!page)
212 goto out;
213
214 spin_lock(&bd_mapping->private_lock);
215 if (!page_has_buffers(page))
216 goto out_unlock;
217 head = page_buffers(page);
218 bh = head;
219 do {
Nikanth Karthikesan97f76d32009-04-02 16:56:46 -0700220 if (!buffer_mapped(bh))
221 all_mapped = 0;
222 else if (bh->b_blocknr == block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 ret = bh;
224 get_bh(bh);
225 goto out_unlock;
226 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 bh = bh->b_this_page;
228 } while (bh != head);
229
230 /* we might be here because some of the buffers on this page are
231 * not mapped. This is due to various races between
232 * file io on the block device and getblk. It gets dealt with
233 * elsewhere, don't buffer_error if we had some unmapped buffers
234 */
235 if (all_mapped) {
Tao Ma72a2ebd2011-10-31 17:09:00 -0700236 char b[BDEVNAME_SIZE];
237
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 printk("__find_get_block_slow() failed. "
239 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800240 (unsigned long long)block,
241 (unsigned long long)bh->b_blocknr);
242 printk("b_state=0x%08lx, b_size=%zu\n",
243 bh->b_state, bh->b_size);
Tao Ma72a2ebd2011-10-31 17:09:00 -0700244 printk("device %s blocksize: %d\n", bdevname(bdev, b),
245 1 << bd_inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 }
247out_unlock:
248 spin_unlock(&bd_mapping->private_lock);
249 page_cache_release(page);
250out:
251 return ret;
252}
253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254/*
Jens Axboe5b0830c2009-09-23 19:37:09 +0200255 * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 */
257static void free_more_memory(void)
258{
Mel Gorman19770b32008-04-28 02:12:18 -0700259 struct zone *zone;
Mel Gorman0e884602008-04-28 02:12:14 -0700260 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -0600262 wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 yield();
264
Mel Gorman0e884602008-04-28 02:12:14 -0700265 for_each_online_node(nid) {
Mel Gorman19770b32008-04-28 02:12:18 -0700266 (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
267 gfp_zone(GFP_NOFS), NULL,
268 &zone);
269 if (zone)
Mel Gorman54a6eb52008-04-28 02:12:16 -0700270 try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700271 GFP_NOFS, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 }
273}
274
275/*
276 * I/O completion handler for block_read_full_page() - pages
277 * which come unlocked at the end of I/O.
278 */
279static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
280{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700282 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 struct buffer_head *tmp;
284 struct page *page;
285 int page_uptodate = 1;
286
287 BUG_ON(!buffer_async_read(bh));
288
289 page = bh->b_page;
290 if (uptodate) {
291 set_buffer_uptodate(bh);
292 } else {
293 clear_buffer_uptodate(bh);
Robert Elliott432f16e2014-10-21 13:55:11 -0600294 buffer_io_error(bh, ", async page read");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 SetPageError(page);
296 }
297
298 /*
299 * Be _very_ careful from here on. Bad things can happen if
300 * two buffer heads end IO at almost the same time and both
301 * decide that the page is now completely done.
302 */
Nick Piggina3972202005-07-07 17:56:56 -0700303 first = page_buffers(page);
304 local_irq_save(flags);
305 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306 clear_buffer_async_read(bh);
307 unlock_buffer(bh);
308 tmp = bh;
309 do {
310 if (!buffer_uptodate(tmp))
311 page_uptodate = 0;
312 if (buffer_async_read(tmp)) {
313 BUG_ON(!buffer_locked(tmp));
314 goto still_busy;
315 }
316 tmp = tmp->b_this_page;
317 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700318 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
319 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
321 /*
322 * If none of the buffers had errors and they are all
323 * uptodate then we can set the page uptodate.
324 */
325 if (page_uptodate && !PageError(page))
326 SetPageUptodate(page);
327 unlock_page(page);
328 return;
329
330still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700331 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
332 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 return;
334}
335
336/*
337 * Completion handler for block_write_full_page() - pages which are unlocked
338 * during I/O, and which have PageWriteback cleared upon I/O completion.
339 */
Chris Mason35c80d52009-04-15 13:22:38 -0400340void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700343 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 struct buffer_head *tmp;
345 struct page *page;
346
347 BUG_ON(!buffer_async_write(bh));
348
349 page = bh->b_page;
350 if (uptodate) {
351 set_buffer_uptodate(bh);
352 } else {
Robert Elliott432f16e2014-10-21 13:55:11 -0600353 buffer_io_error(bh, ", lost async page write");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 set_bit(AS_EIO, &page->mapping->flags);
Jan Kara58ff4072006-10-17 00:10:19 -0700355 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 clear_buffer_uptodate(bh);
357 SetPageError(page);
358 }
359
Nick Piggina3972202005-07-07 17:56:56 -0700360 first = page_buffers(page);
361 local_irq_save(flags);
362 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
363
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 clear_buffer_async_write(bh);
365 unlock_buffer(bh);
366 tmp = bh->b_this_page;
367 while (tmp != bh) {
368 if (buffer_async_write(tmp)) {
369 BUG_ON(!buffer_locked(tmp));
370 goto still_busy;
371 }
372 tmp = tmp->b_this_page;
373 }
Nick Piggina3972202005-07-07 17:56:56 -0700374 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
375 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 end_page_writeback(page);
377 return;
378
379still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700380 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
381 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 return;
383}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700384EXPORT_SYMBOL(end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385
386/*
387 * If a page's buffers are under async readin (end_buffer_async_read
388 * completion) then there is a possibility that another thread of
389 * control could lock one of the buffers after it has completed
390 * but while some of the other buffers have not completed. This
391 * locked buffer would confuse end_buffer_async_read() into not unlocking
392 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
393 * that this buffer is not under async I/O.
394 *
395 * The page comes unlocked when it has no locked buffer_async buffers
396 * left.
397 *
398 * PageLocked prevents anyone starting new async I/O reads any of
399 * the buffers.
400 *
401 * PageWriteback is used to prevent simultaneous writeout of the same
402 * page.
403 *
404 * PageLocked prevents anyone from starting writeback of a page which is
405 * under read I/O (PageWriteback is only ever set against a locked page).
406 */
407static void mark_buffer_async_read(struct buffer_head *bh)
408{
409 bh->b_end_io = end_buffer_async_read;
410 set_buffer_async_read(bh);
411}
412
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700413static void mark_buffer_async_write_endio(struct buffer_head *bh,
414 bh_end_io_t *handler)
Chris Mason35c80d52009-04-15 13:22:38 -0400415{
416 bh->b_end_io = handler;
417 set_buffer_async_write(bh);
418}
419
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420void mark_buffer_async_write(struct buffer_head *bh)
421{
Chris Mason35c80d52009-04-15 13:22:38 -0400422 mark_buffer_async_write_endio(bh, end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423}
424EXPORT_SYMBOL(mark_buffer_async_write);
425
426
427/*
428 * fs/buffer.c contains helper functions for buffer-backed address space's
429 * fsync functions. A common requirement for buffer-based filesystems is
430 * that certain data from the backing blockdev needs to be written out for
431 * a successful fsync(). For example, ext2 indirect blocks need to be
432 * written back and waited upon before fsync() returns.
433 *
434 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
435 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
436 * management of a list of dependent buffers at ->i_mapping->private_list.
437 *
438 * Locking is a little subtle: try_to_free_buffers() will remove buffers
439 * from their controlling inode's queue when they are being freed. But
440 * try_to_free_buffers() will be operating against the *blockdev* mapping
441 * at the time, not against the S_ISREG file which depends on those buffers.
442 * So the locking for private_list is via the private_lock in the address_space
443 * which backs the buffers. Which is different from the address_space
444 * against which the buffers are listed. So for a particular address_space,
445 * mapping->private_lock does *not* protect mapping->private_list! In fact,
446 * mapping->private_list will always be protected by the backing blockdev's
447 * ->private_lock.
448 *
449 * Which introduces a requirement: all buffers on an address_space's
450 * ->private_list must be from the same address_space: the blockdev's.
451 *
452 * address_spaces which do not place buffers at ->private_list via these
453 * utility functions are free to use private_lock and private_list for
454 * whatever they want. The only requirement is that list_empty(private_list)
455 * be true at clear_inode() time.
456 *
457 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
458 * filesystems should do that. invalidate_inode_buffers() should just go
459 * BUG_ON(!list_empty).
460 *
461 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
462 * take an address_space, not an inode. And it should be called
463 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
464 * queued up.
465 *
466 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
467 * list if it is already on a list. Because if the buffer is on a list,
468 * it *must* already be on the right one. If not, the filesystem is being
469 * silly. This will save a ton of locking. But first we have to ensure
470 * that buffers are taken *off* the old inode's list when they are freed
471 * (presumably in truncate). That requires careful auditing of all
472 * filesystems (do it inside bforget()). It could also be done by bringing
473 * b_inode back.
474 */
475
476/*
477 * The buffer's backing address_space's private_lock must be held
478 */
Thomas Petazzonidbacefc2008-07-29 22:33:47 -0700479static void __remove_assoc_queue(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480{
481 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -0700482 WARN_ON(!bh->b_assoc_map);
483 if (buffer_write_io_error(bh))
484 set_bit(AS_EIO, &bh->b_assoc_map->flags);
485 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486}
487
488int inode_has_buffers(struct inode *inode)
489{
490 return !list_empty(&inode->i_data.private_list);
491}
492
493/*
494 * osync is designed to support O_SYNC io. It waits synchronously for
495 * all already-submitted IO to complete, but does not queue any new
496 * writes to the disk.
497 *
498 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
499 * you dirty the buffers, and then use osync_inode_buffers to wait for
500 * completion. Any other dirty buffers which are not yet queued for
501 * write will not be flushed to disk by the osync.
502 */
503static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
504{
505 struct buffer_head *bh;
506 struct list_head *p;
507 int err = 0;
508
509 spin_lock(lock);
510repeat:
511 list_for_each_prev(p, list) {
512 bh = BH_ENTRY(p);
513 if (buffer_locked(bh)) {
514 get_bh(bh);
515 spin_unlock(lock);
516 wait_on_buffer(bh);
517 if (!buffer_uptodate(bh))
518 err = -EIO;
519 brelse(bh);
520 spin_lock(lock);
521 goto repeat;
522 }
523 }
524 spin_unlock(lock);
525 return err;
526}
527
Al Viro01a05b32010-03-23 06:06:58 -0400528static void do_thaw_one(struct super_block *sb, void *unused)
529{
530 char b[BDEVNAME_SIZE];
531 while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
532 printk(KERN_WARNING "Emergency Thaw on %s\n",
533 bdevname(sb->s_bdev, b));
534}
535
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700536static void do_thaw_all(struct work_struct *work)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700537{
Al Viro01a05b32010-03-23 06:06:58 -0400538 iterate_supers(do_thaw_one, NULL);
Jens Axboe053c5252009-04-08 13:44:08 +0200539 kfree(work);
Eric Sandeenc2d75432009-03-31 15:23:46 -0700540 printk(KERN_WARNING "Emergency Thaw complete\n");
541}
542
543/**
544 * emergency_thaw_all -- forcibly thaw every frozen filesystem
545 *
546 * Used for emergency unfreeze of all filesystems via SysRq
547 */
548void emergency_thaw_all(void)
549{
Jens Axboe053c5252009-04-08 13:44:08 +0200550 struct work_struct *work;
551
552 work = kmalloc(sizeof(*work), GFP_ATOMIC);
553 if (work) {
554 INIT_WORK(work, do_thaw_all);
555 schedule_work(work);
556 }
Eric Sandeenc2d75432009-03-31 15:23:46 -0700557}
558
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800560 * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700561 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700562 *
563 * Starts I/O against the buffers at mapping->private_list, and waits upon
564 * that I/O.
565 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700566 * Basically, this is a convenience function for fsync().
567 * @mapping is a file or directory which needs those buffers to be written for
568 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 */
570int sync_mapping_buffers(struct address_space *mapping)
571{
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800572 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700573
574 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
575 return 0;
576
577 return fsync_buffers_list(&buffer_mapping->private_lock,
578 &mapping->private_list);
579}
580EXPORT_SYMBOL(sync_mapping_buffers);
581
582/*
583 * Called when we've recently written block `bblock', and it is known that
584 * `bblock' was for a buffer_boundary() buffer. This means that the block at
585 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
586 * dirty, schedule it for IO. So that indirects merge nicely with their data.
587 */
588void write_boundary_block(struct block_device *bdev,
589 sector_t bblock, unsigned blocksize)
590{
591 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
592 if (bh) {
593 if (buffer_dirty(bh))
594 ll_rw_block(WRITE, 1, &bh);
595 put_bh(bh);
596 }
597}
598
599void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
600{
601 struct address_space *mapping = inode->i_mapping;
602 struct address_space *buffer_mapping = bh->b_page->mapping;
603
604 mark_buffer_dirty(bh);
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800605 if (!mapping->private_data) {
606 mapping->private_data = buffer_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 } else {
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800608 BUG_ON(mapping->private_data != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 }
Jan Kara535ee2f2008-02-08 04:21:59 -0800610 if (!bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 spin_lock(&buffer_mapping->private_lock);
612 list_move_tail(&bh->b_assoc_buffers,
613 &mapping->private_list);
Jan Kara58ff4072006-10-17 00:10:19 -0700614 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 spin_unlock(&buffer_mapping->private_lock);
616 }
617}
618EXPORT_SYMBOL(mark_buffer_dirty_inode);
619
620/*
Nick Piggin787d2212007-07-17 04:03:34 -0700621 * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
622 * dirty.
623 *
624 * If warn is true, then emit a warning if the page is not uptodate and has
625 * not been truncated.
626 */
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700627static void __set_page_dirty(struct page *page,
Nick Piggin787d2212007-07-17 04:03:34 -0700628 struct address_space *mapping, int warn)
629{
KOSAKI Motohiro227d53b32014-02-06 12:04:28 -0800630 unsigned long flags;
631
632 spin_lock_irqsave(&mapping->tree_lock, flags);
Nick Piggin787d2212007-07-17 04:03:34 -0700633 if (page->mapping) { /* Race with truncate? */
634 WARN_ON_ONCE(warn && !PageUptodate(page));
Edward Shishkine3a7cca2009-03-31 15:19:39 -0700635 account_page_dirtied(page, mapping);
Nick Piggin787d2212007-07-17 04:03:34 -0700636 radix_tree_tag_set(&mapping->page_tree,
637 page_index(page), PAGECACHE_TAG_DIRTY);
638 }
KOSAKI Motohiro227d53b32014-02-06 12:04:28 -0800639 spin_unlock_irqrestore(&mapping->tree_lock, flags);
Nick Piggin787d2212007-07-17 04:03:34 -0700640 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Nick Piggin787d2212007-07-17 04:03:34 -0700641}
642
643/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644 * Add a page to the dirty page list.
645 *
646 * It is a sad fact of life that this function is called from several places
647 * deeply under spinlocking. It may not sleep.
648 *
649 * If the page has buffers, the uptodate buffers are set dirty, to preserve
650 * dirty-state coherency between the page and the buffers. It the page does
651 * not have buffers then when they are later attached they will all be set
652 * dirty.
653 *
654 * The buffers are dirtied before the page is dirtied. There's a small race
655 * window in which a writepage caller may see the page cleanness but not the
656 * buffer dirtiness. That's fine. If this code were to set the page dirty
657 * before the buffers, a concurrent writepage caller could clear the page dirty
658 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
659 * page on the dirty page list.
660 *
661 * We use private_lock to lock against try_to_free_buffers while using the
662 * page's buffer list. Also use this to protect against clean buffers being
663 * added to the page after it was set dirty.
664 *
665 * FIXME: may need to call ->reservepage here as well. That's rather up to the
666 * address_space though.
667 */
668int __set_page_dirty_buffers(struct page *page)
669{
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700670 int newly_dirty;
Nick Piggin787d2212007-07-17 04:03:34 -0700671 struct address_space *mapping = page_mapping(page);
Nick Pigginebf7a222006-10-10 04:36:54 +0200672
673 if (unlikely(!mapping))
674 return !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
676 spin_lock(&mapping->private_lock);
677 if (page_has_buffers(page)) {
678 struct buffer_head *head = page_buffers(page);
679 struct buffer_head *bh = head;
680
681 do {
682 set_buffer_dirty(bh);
683 bh = bh->b_this_page;
684 } while (bh != head);
685 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700686 newly_dirty = !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 spin_unlock(&mapping->private_lock);
688
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700689 if (newly_dirty)
690 __set_page_dirty(page, mapping, 1);
691 return newly_dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692}
693EXPORT_SYMBOL(__set_page_dirty_buffers);
694
695/*
696 * Write out and wait upon a list of buffers.
697 *
698 * We have conflicting pressures: we want to make sure that all
699 * initially dirty buffers get waited on, but that any subsequently
700 * dirtied buffers don't. After all, we don't want fsync to last
701 * forever if somebody is actively writing to the file.
702 *
703 * Do this in two main stages: first we copy dirty buffers to a
704 * temporary inode list, queueing the writes as we go. Then we clean
705 * up, waiting for those writes to complete.
706 *
707 * During this second stage, any subsequent updates to the file may end
708 * up refiling the buffer on the original inode's dirty list again, so
709 * there is a chance we will end up with a buffer queued for write but
710 * not yet completed on that list. So, as a final cleanup we go through
711 * the osync code to catch these locked, dirty buffers without requeuing
712 * any newly dirty buffers for write.
713 */
714static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
715{
716 struct buffer_head *bh;
717 struct list_head tmp;
Jens Axboe7eaceac2011-03-10 08:52:07 +0100718 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 int err = 0, err2;
Jens Axboe4ee24912011-03-17 10:51:40 +0100720 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721
722 INIT_LIST_HEAD(&tmp);
Jens Axboe4ee24912011-03-17 10:51:40 +0100723 blk_start_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724
725 spin_lock(lock);
726 while (!list_empty(list)) {
727 bh = BH_ENTRY(list->next);
Jan Kara535ee2f2008-02-08 04:21:59 -0800728 mapping = bh->b_assoc_map;
Jan Kara58ff4072006-10-17 00:10:19 -0700729 __remove_assoc_queue(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800730 /* Avoid race with mark_buffer_dirty_inode() which does
731 * a lockless check and we rely on seeing the dirty bit */
732 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 if (buffer_dirty(bh) || buffer_locked(bh)) {
734 list_add(&bh->b_assoc_buffers, &tmp);
Jan Kara535ee2f2008-02-08 04:21:59 -0800735 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 if (buffer_dirty(bh)) {
737 get_bh(bh);
738 spin_unlock(lock);
739 /*
740 * Ensure any pending I/O completes so that
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200741 * write_dirty_buffer() actually writes the
742 * current contents - it is a noop if I/O is
743 * still in flight on potentially older
744 * contents.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 */
Jens Axboe721a9602011-03-09 11:56:30 +0100746 write_dirty_buffer(bh, WRITE_SYNC);
Jens Axboe9cf6b722009-04-06 14:48:03 +0200747
748 /*
749 * Kick off IO for the previous mapping. Note
750 * that we will not run the very last mapping,
751 * wait_on_buffer() will do that for us
752 * through sync_buffer().
753 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 brelse(bh);
755 spin_lock(lock);
756 }
757 }
758 }
759
Jens Axboe4ee24912011-03-17 10:51:40 +0100760 spin_unlock(lock);
761 blk_finish_plug(&plug);
762 spin_lock(lock);
763
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 while (!list_empty(&tmp)) {
765 bh = BH_ENTRY(tmp.prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 get_bh(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800767 mapping = bh->b_assoc_map;
768 __remove_assoc_queue(bh);
769 /* Avoid race with mark_buffer_dirty_inode() which does
770 * a lockless check and we rely on seeing the dirty bit */
771 smp_mb();
772 if (buffer_dirty(bh)) {
773 list_add(&bh->b_assoc_buffers,
Jan Karae3892292008-03-04 14:28:33 -0800774 &mapping->private_list);
Jan Kara535ee2f2008-02-08 04:21:59 -0800775 bh->b_assoc_map = mapping;
776 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 spin_unlock(lock);
778 wait_on_buffer(bh);
779 if (!buffer_uptodate(bh))
780 err = -EIO;
781 brelse(bh);
782 spin_lock(lock);
783 }
784
785 spin_unlock(lock);
786 err2 = osync_buffers_list(lock, list);
787 if (err)
788 return err;
789 else
790 return err2;
791}
792
793/*
794 * Invalidate any and all dirty buffers on a given inode. We are
795 * probably unmounting the fs, but that doesn't mean we have already
796 * done a sync(). Just drop the buffers from the inode list.
797 *
798 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
799 * assumes that all the buffers are against the blockdev. Not true
800 * for reiserfs.
801 */
802void invalidate_inode_buffers(struct inode *inode)
803{
804 if (inode_has_buffers(inode)) {
805 struct address_space *mapping = &inode->i_data;
806 struct list_head *list = &mapping->private_list;
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800807 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808
809 spin_lock(&buffer_mapping->private_lock);
810 while (!list_empty(list))
811 __remove_assoc_queue(BH_ENTRY(list->next));
812 spin_unlock(&buffer_mapping->private_lock);
813 }
814}
Jan Kara52b19ac2008-09-23 18:24:08 +0200815EXPORT_SYMBOL(invalidate_inode_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816
817/*
818 * Remove any clean buffers from the inode's buffer list. This is called
819 * when we're trying to free the inode itself. Those buffers can pin it.
820 *
821 * Returns true if all buffers were removed.
822 */
823int remove_inode_buffers(struct inode *inode)
824{
825 int ret = 1;
826
827 if (inode_has_buffers(inode)) {
828 struct address_space *mapping = &inode->i_data;
829 struct list_head *list = &mapping->private_list;
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800830 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831
832 spin_lock(&buffer_mapping->private_lock);
833 while (!list_empty(list)) {
834 struct buffer_head *bh = BH_ENTRY(list->next);
835 if (buffer_dirty(bh)) {
836 ret = 0;
837 break;
838 }
839 __remove_assoc_queue(bh);
840 }
841 spin_unlock(&buffer_mapping->private_lock);
842 }
843 return ret;
844}
845
846/*
847 * Create the appropriate buffers when given a page for data area and
848 * the size of each buffer.. Use the bh->b_this_page linked list to
849 * follow the buffers created. Return NULL if unable to create more
850 * buffers.
851 *
852 * The retry flag is used to differentiate async IO (paging, swapping)
853 * which may not fail from ordinary buffer allocations.
854 */
855struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
856 int retry)
857{
858 struct buffer_head *bh, *head;
859 long offset;
860
861try_again:
862 head = NULL;
863 offset = PAGE_SIZE;
864 while ((offset -= size) >= 0) {
865 bh = alloc_buffer_head(GFP_NOFS);
866 if (!bh)
867 goto no_grow;
868
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 bh->b_this_page = head;
870 bh->b_blocknr = -1;
871 head = bh;
872
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 bh->b_size = size;
874
875 /* Link the buffer to its page */
876 set_bh_page(bh, page, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 }
878 return head;
879/*
880 * In case anything failed, we just free everything we got.
881 */
882no_grow:
883 if (head) {
884 do {
885 bh = head;
886 head = head->b_this_page;
887 free_buffer_head(bh);
888 } while (head);
889 }
890
891 /*
892 * Return failure for non-async IO requests. Async IO requests
893 * are not allowed to fail, so we have to wait until buffer heads
894 * become available. But we don't want tasks sleeping with
895 * partially complete buffers, so all were released above.
896 */
897 if (!retry)
898 return NULL;
899
900 /* We're _really_ low on memory. Now we just
901 * wait for old buffer heads to become free due to
902 * finishing IO. Since this is an async request and
903 * the reserve list is empty, we're sure there are
904 * async buffer heads in use.
905 */
906 free_more_memory();
907 goto try_again;
908}
909EXPORT_SYMBOL_GPL(alloc_page_buffers);
910
911static inline void
912link_dev_buffers(struct page *page, struct buffer_head *head)
913{
914 struct buffer_head *bh, *tail;
915
916 bh = head;
917 do {
918 tail = bh;
919 bh = bh->b_this_page;
920 } while (bh);
921 tail->b_this_page = head;
922 attach_page_buffers(page, head);
923}
924
Linus Torvaldsbbec02702012-11-29 12:31:52 -0800925static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
926{
927 sector_t retval = ~((sector_t)0);
928 loff_t sz = i_size_read(bdev->bd_inode);
929
930 if (sz) {
931 unsigned int sizebits = blksize_bits(size);
932 retval = (sz >> sizebits);
933 }
934 return retval;
935}
936
Linus Torvalds1da177e2005-04-16 15:20:36 -0700937/*
938 * Initialise the state of a blockdev page's buffers.
939 */
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200940static sector_t
Linus Torvalds1da177e2005-04-16 15:20:36 -0700941init_page_buffers(struct page *page, struct block_device *bdev,
942 sector_t block, int size)
943{
944 struct buffer_head *head = page_buffers(page);
945 struct buffer_head *bh = head;
946 int uptodate = PageUptodate(page);
Linus Torvaldsbbec02702012-11-29 12:31:52 -0800947 sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948
949 do {
950 if (!buffer_mapped(bh)) {
951 init_buffer(bh, NULL, NULL);
952 bh->b_bdev = bdev;
953 bh->b_blocknr = block;
954 if (uptodate)
955 set_buffer_uptodate(bh);
Jeff Moyer080399a2012-05-11 16:34:10 +0200956 if (block < end_block)
957 set_buffer_mapped(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958 }
959 block++;
960 bh = bh->b_this_page;
961 } while (bh != head);
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200962
963 /*
964 * Caller needs to validate requested block against end of device.
965 */
966 return end_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967}
968
969/*
970 * Create the page-cache page that contains the requested block.
971 *
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200972 * This is used purely for blockdev mappings.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 */
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200974static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975grow_dev_page(struct block_device *bdev, sector_t block,
Gioh Kim3b5e6452014-09-04 22:04:42 -0400976 pgoff_t index, int size, int sizebits, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977{
978 struct inode *inode = bdev->bd_inode;
979 struct page *page;
980 struct buffer_head *bh;
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200981 sector_t end_block;
982 int ret = 0; /* Will call free_more_memory() */
Johannes Weiner84235de2013-10-16 13:47:00 -0700983 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984
Gioh Kim3b5e6452014-09-04 22:04:42 -0400985 gfp_mask = (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS) | gfp;
986
Johannes Weiner84235de2013-10-16 13:47:00 -0700987 /*
988 * XXX: __getblk_slow() can not really deal with failure and
989 * will endlessly loop on improvised global reclaim. Prefer
990 * looping in the allocator rather than here, at least that
991 * code knows what it's doing.
992 */
993 gfp_mask |= __GFP_NOFAIL;
994
995 page = find_or_create_page(inode->i_mapping, index, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 if (!page)
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200997 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998
Eric Sesterhenne827f922006-03-26 18:24:46 +0200999 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000
1001 if (page_has_buffers(page)) {
1002 bh = page_buffers(page);
1003 if (bh->b_size == size) {
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001004 end_block = init_page_buffers(page, bdev,
Anton Altaparmakovf2d5a942014-09-22 01:53:03 +01001005 (sector_t)index << sizebits,
1006 size);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001007 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008 }
1009 if (!try_to_free_buffers(page))
1010 goto failed;
1011 }
1012
1013 /*
1014 * Allocate some buffers for this page
1015 */
1016 bh = alloc_page_buffers(page, size, 0);
1017 if (!bh)
1018 goto failed;
1019
1020 /*
1021 * Link the page to the buffers and initialise them. Take the
1022 * lock to be atomic wrt __find_get_block(), which does not
1023 * run under the page lock.
1024 */
1025 spin_lock(&inode->i_mapping->private_lock);
1026 link_dev_buffers(page, bh);
Anton Altaparmakovf2d5a942014-09-22 01:53:03 +01001027 end_block = init_page_buffers(page, bdev, (sector_t)index << sizebits,
1028 size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 spin_unlock(&inode->i_mapping->private_lock);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001030done:
1031 ret = (block < end_block) ? 1 : -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001032failed:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001033 unlock_page(page);
1034 page_cache_release(page);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001035 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036}
1037
1038/*
1039 * Create buffers for the specified block device block's page. If
1040 * that page was dirty, the buffers are set dirty also.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001041 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001042static int
Gioh Kim3b5e6452014-09-04 22:04:42 -04001043grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045 pgoff_t index;
1046 int sizebits;
1047
1048 sizebits = -1;
1049 do {
1050 sizebits++;
1051 } while ((size << sizebits) < PAGE_SIZE);
1052
1053 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054
Andrew Mortone5657932006-10-11 01:21:46 -07001055 /*
1056 * Check for a block which wants to lie outside our maximum possible
1057 * pagecache index. (this comparison is done using sector_t types).
1058 */
1059 if (unlikely(index != block >> sizebits)) {
1060 char b[BDEVNAME_SIZE];
1061
1062 printk(KERN_ERR "%s: requested out-of-range block %llu for "
1063 "device %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07001064 __func__, (unsigned long long)block,
Andrew Mortone5657932006-10-11 01:21:46 -07001065 bdevname(bdev, b));
1066 return -EIO;
1067 }
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001068
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069 /* Create a page with the proper size buffers.. */
Gioh Kim3b5e6452014-09-04 22:04:42 -04001070 return grow_dev_page(bdev, block, index, size, sizebits, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071}
1072
Gioh Kim3b5e6452014-09-04 22:04:42 -04001073struct buffer_head *
1074__getblk_slow(struct block_device *bdev, sector_t block,
1075 unsigned size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076{
1077 /* Size must be multiple of hard sectorsize */
Martin K. Petersene1defc42009-05-22 17:17:49 -04001078 if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 (size < 512 || size > PAGE_SIZE))) {
1080 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1081 size);
Martin K. Petersene1defc42009-05-22 17:17:49 -04001082 printk(KERN_ERR "logical block size: %d\n",
1083 bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084
1085 dump_stack();
1086 return NULL;
1087 }
1088
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001089 for (;;) {
1090 struct buffer_head *bh;
1091 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092
1093 bh = __find_get_block(bdev, block, size);
1094 if (bh)
1095 return bh;
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001096
Gioh Kim3b5e6452014-09-04 22:04:42 -04001097 ret = grow_buffers(bdev, block, size, gfp);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001098 if (ret < 0)
1099 return NULL;
1100 if (ret == 0)
1101 free_more_memory();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 }
1103}
Gioh Kim3b5e6452014-09-04 22:04:42 -04001104EXPORT_SYMBOL(__getblk_slow);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105
1106/*
1107 * The relationship between dirty buffers and dirty pages:
1108 *
1109 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1110 * the page is tagged dirty in its radix tree.
1111 *
1112 * At all times, the dirtiness of the buffers represents the dirtiness of
1113 * subsections of the page. If the page has buffers, the page dirty bit is
1114 * merely a hint about the true dirty state.
1115 *
1116 * When a page is set dirty in its entirety, all its buffers are marked dirty
1117 * (if the page has buffers).
1118 *
1119 * When a buffer is marked dirty, its page is dirtied, but the page's other
1120 * buffers are not.
1121 *
1122 * Also. When blockdev buffers are explicitly read with bread(), they
1123 * individually become uptodate. But their backing page remains not
1124 * uptodate - even if all of its buffers are uptodate. A subsequent
1125 * block_read_full_page() against that page will discover all the uptodate
1126 * buffers, will set the page uptodate and will perform no I/O.
1127 */
1128
1129/**
1130 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001131 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132 *
1133 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1134 * backing page dirty, then tag the page as dirty in its address_space's radix
1135 * tree and then attach the address_space's inode to its superblock's dirty
1136 * inode list.
1137 *
1138 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
Dave Chinner250df6e2011-03-22 22:23:36 +11001139 * mapping->tree_lock and mapping->host->i_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001141void mark_buffer_dirty(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142{
Nick Piggin787d2212007-07-17 04:03:34 -07001143 WARN_ON_ONCE(!buffer_uptodate(bh));
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001144
Tejun Heo5305cb82013-01-11 13:06:36 -08001145 trace_block_dirty_buffer(bh);
1146
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001147 /*
1148 * Very *carefully* optimize the it-is-already-dirty case.
1149 *
1150 * Don't let the final "is it dirty" escape to before we
1151 * perhaps modified the buffer.
1152 */
1153 if (buffer_dirty(bh)) {
1154 smp_mb();
1155 if (buffer_dirty(bh))
1156 return;
1157 }
1158
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001159 if (!test_set_buffer_dirty(bh)) {
1160 struct page *page = bh->b_page;
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001161 if (!TestSetPageDirty(page)) {
1162 struct address_space *mapping = page_mapping(page);
1163 if (mapping)
1164 __set_page_dirty(page, mapping, 0);
1165 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001166 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001168EXPORT_SYMBOL(mark_buffer_dirty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169
1170/*
1171 * Decrement a buffer_head's reference count. If all buffers against a page
1172 * have zero reference count, are clean and unlocked, and if the page is clean
1173 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1174 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1175 * a page but it ends up not being freed, and buffers may later be reattached).
1176 */
1177void __brelse(struct buffer_head * buf)
1178{
1179 if (atomic_read(&buf->b_count)) {
1180 put_bh(buf);
1181 return;
1182 }
Arjan van de Ven5c752ad2008-07-25 19:45:40 -07001183 WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001185EXPORT_SYMBOL(__brelse);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186
1187/*
1188 * bforget() is like brelse(), except it discards any
1189 * potentially dirty data.
1190 */
1191void __bforget(struct buffer_head *bh)
1192{
1193 clear_buffer_dirty(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -08001194 if (bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 struct address_space *buffer_mapping = bh->b_page->mapping;
1196
1197 spin_lock(&buffer_mapping->private_lock);
1198 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -07001199 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 spin_unlock(&buffer_mapping->private_lock);
1201 }
1202 __brelse(bh);
1203}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001204EXPORT_SYMBOL(__bforget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205
1206static struct buffer_head *__bread_slow(struct buffer_head *bh)
1207{
1208 lock_buffer(bh);
1209 if (buffer_uptodate(bh)) {
1210 unlock_buffer(bh);
1211 return bh;
1212 } else {
1213 get_bh(bh);
1214 bh->b_end_io = end_buffer_read_sync;
1215 submit_bh(READ, bh);
1216 wait_on_buffer(bh);
1217 if (buffer_uptodate(bh))
1218 return bh;
1219 }
1220 brelse(bh);
1221 return NULL;
1222}
1223
1224/*
1225 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1226 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1227 * refcount elevated by one when they're in an LRU. A buffer can only appear
1228 * once in a particular CPU's LRU. A single buffer can be present in multiple
1229 * CPU's LRUs at the same time.
1230 *
1231 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1232 * sb_find_get_block().
1233 *
1234 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1235 * a local interrupt disable for that.
1236 */
1237
Sebastien Buisson86cf78d2014-10-09 15:29:38 -07001238#define BH_LRU_SIZE 16
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239
1240struct bh_lru {
1241 struct buffer_head *bhs[BH_LRU_SIZE];
1242};
1243
1244static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1245
1246#ifdef CONFIG_SMP
1247#define bh_lru_lock() local_irq_disable()
1248#define bh_lru_unlock() local_irq_enable()
1249#else
1250#define bh_lru_lock() preempt_disable()
1251#define bh_lru_unlock() preempt_enable()
1252#endif
1253
1254static inline void check_irqs_on(void)
1255{
1256#ifdef irqs_disabled
1257 BUG_ON(irqs_disabled());
1258#endif
1259}
1260
1261/*
1262 * The LRU management algorithm is dopey-but-simple. Sorry.
1263 */
1264static void bh_lru_install(struct buffer_head *bh)
1265{
1266 struct buffer_head *evictee = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267
1268 check_irqs_on();
1269 bh_lru_lock();
Christoph Lameterc7b92512010-12-06 11:16:28 -06001270 if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001271 struct buffer_head *bhs[BH_LRU_SIZE];
1272 int in;
1273 int out = 0;
1274
1275 get_bh(bh);
1276 bhs[out++] = bh;
1277 for (in = 0; in < BH_LRU_SIZE; in++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001278 struct buffer_head *bh2 =
1279 __this_cpu_read(bh_lrus.bhs[in]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280
1281 if (bh2 == bh) {
1282 __brelse(bh2);
1283 } else {
1284 if (out >= BH_LRU_SIZE) {
1285 BUG_ON(evictee != NULL);
1286 evictee = bh2;
1287 } else {
1288 bhs[out++] = bh2;
1289 }
1290 }
1291 }
1292 while (out < BH_LRU_SIZE)
1293 bhs[out++] = NULL;
Christoph Lameterca6673b02013-12-03 17:32:53 -06001294 memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 }
1296 bh_lru_unlock();
1297
1298 if (evictee)
1299 __brelse(evictee);
1300}
1301
1302/*
1303 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1304 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001305static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001306lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307{
1308 struct buffer_head *ret = NULL;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001309 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001310
1311 check_irqs_on();
1312 bh_lru_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313 for (i = 0; i < BH_LRU_SIZE; i++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001314 struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315
Zach Brown9470dd52014-10-13 15:55:05 -07001316 if (bh && bh->b_blocknr == block && bh->b_bdev == bdev &&
1317 bh->b_size == size) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318 if (i) {
1319 while (i) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001320 __this_cpu_write(bh_lrus.bhs[i],
1321 __this_cpu_read(bh_lrus.bhs[i - 1]));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 i--;
1323 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06001324 __this_cpu_write(bh_lrus.bhs[0], bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 }
1326 get_bh(bh);
1327 ret = bh;
1328 break;
1329 }
1330 }
1331 bh_lru_unlock();
1332 return ret;
1333}
1334
1335/*
1336 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1337 * it in the LRU and mark it as accessed. If it is not present then return
1338 * NULL
1339 */
1340struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001341__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342{
1343 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1344
1345 if (bh == NULL) {
Mel Gorman2457aec2014-06-04 16:10:31 -07001346 /* __find_get_block_slow will mark the page accessed */
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001347 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 if (bh)
1349 bh_lru_install(bh);
Mel Gorman2457aec2014-06-04 16:10:31 -07001350 } else
Linus Torvalds1da177e2005-04-16 15:20:36 -07001351 touch_buffer(bh);
Mel Gorman2457aec2014-06-04 16:10:31 -07001352
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 return bh;
1354}
1355EXPORT_SYMBOL(__find_get_block);
1356
1357/*
Gioh Kim3b5e6452014-09-04 22:04:42 -04001358 * __getblk_gfp() will locate (and, if necessary, create) the buffer_head
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359 * which corresponds to the passed block_device, block and size. The
1360 * returned buffer has its reference count incremented.
1361 *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001362 * __getblk_gfp() will lock up the machine if grow_dev_page's
1363 * try_to_free_buffers() attempt is failing. FIXME, perhaps?
Linus Torvalds1da177e2005-04-16 15:20:36 -07001364 */
1365struct buffer_head *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001366__getblk_gfp(struct block_device *bdev, sector_t block,
1367 unsigned size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368{
1369 struct buffer_head *bh = __find_get_block(bdev, block, size);
1370
1371 might_sleep();
1372 if (bh == NULL)
Gioh Kim3b5e6452014-09-04 22:04:42 -04001373 bh = __getblk_slow(bdev, block, size, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 return bh;
1375}
Gioh Kim3b5e6452014-09-04 22:04:42 -04001376EXPORT_SYMBOL(__getblk_gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377
1378/*
1379 * Do async read-ahead on a buffer..
1380 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001381void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001382{
1383 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001384 if (likely(bh)) {
1385 ll_rw_block(READA, 1, &bh);
1386 brelse(bh);
1387 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388}
1389EXPORT_SYMBOL(__breadahead);
1390
1391/**
Gioh Kim3b5e6452014-09-04 22:04:42 -04001392 * __bread_gfp() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001393 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 * @block: number of block
1395 * @size: size (in bytes) to read
Gioh Kim3b5e6452014-09-04 22:04:42 -04001396 * @gfp: page allocation flag
1397 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 * Reads a specified block, and returns buffer head that contains it.
Gioh Kim3b5e6452014-09-04 22:04:42 -04001399 * The page cache can be allocated from non-movable area
1400 * not to prevent page migration if you set gfp to zero.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 * It returns NULL if the block was unreadable.
1402 */
1403struct buffer_head *
Gioh Kim3b5e6452014-09-04 22:04:42 -04001404__bread_gfp(struct block_device *bdev, sector_t block,
1405 unsigned size, gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406{
Gioh Kim3b5e6452014-09-04 22:04:42 -04001407 struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001408
Andrew Mortona3e713b2005-10-30 15:03:15 -08001409 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 bh = __bread_slow(bh);
1411 return bh;
1412}
Gioh Kim3b5e6452014-09-04 22:04:42 -04001413EXPORT_SYMBOL(__bread_gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414
1415/*
1416 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1417 * This doesn't race because it runs in each cpu either in irq
1418 * or with preempt disabled.
1419 */
1420static void invalidate_bh_lru(void *arg)
1421{
1422 struct bh_lru *b = &get_cpu_var(bh_lrus);
1423 int i;
1424
1425 for (i = 0; i < BH_LRU_SIZE; i++) {
1426 brelse(b->bhs[i]);
1427 b->bhs[i] = NULL;
1428 }
1429 put_cpu_var(bh_lrus);
1430}
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001431
1432static bool has_bh_in_lru(int cpu, void *dummy)
1433{
1434 struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
1435 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001437 for (i = 0; i < BH_LRU_SIZE; i++) {
1438 if (b->bhs[i])
1439 return 1;
1440 }
1441
1442 return 0;
1443}
1444
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001445void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446{
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001447 on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001448}
Nick Piggin9db55792008-02-08 04:19:49 -08001449EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001450
1451void set_bh_page(struct buffer_head *bh,
1452 struct page *page, unsigned long offset)
1453{
1454 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001455 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456 if (PageHighMem(page))
1457 /*
1458 * This catches illegal uses and preserves the offset:
1459 */
1460 bh->b_data = (char *)(0 + offset);
1461 else
1462 bh->b_data = page_address(page) + offset;
1463}
1464EXPORT_SYMBOL(set_bh_page);
1465
1466/*
1467 * Called when truncating a buffer on a page completely.
1468 */
Mel Gormane7470ee2014-06-04 16:10:29 -07001469
1470/* Bits that are cleared during an invalidate */
1471#define BUFFER_FLAGS_DISCARD \
1472 (1 << BH_Mapped | 1 << BH_New | 1 << BH_Req | \
1473 1 << BH_Delay | 1 << BH_Unwritten)
1474
Arjan van de Ven858119e2006-01-14 13:20:43 -08001475static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476{
Mel Gormane7470ee2014-06-04 16:10:29 -07001477 unsigned long b_state, b_state_old;
1478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 lock_buffer(bh);
1480 clear_buffer_dirty(bh);
1481 bh->b_bdev = NULL;
Mel Gormane7470ee2014-06-04 16:10:29 -07001482 b_state = bh->b_state;
1483 for (;;) {
1484 b_state_old = cmpxchg(&bh->b_state, b_state,
1485 (b_state & ~BUFFER_FLAGS_DISCARD));
1486 if (b_state_old == b_state)
1487 break;
1488 b_state = b_state_old;
1489 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 unlock_buffer(bh);
1491}
1492
1493/**
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001494 * block_invalidatepage - invalidate part or all of a buffer-backed page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 *
1496 * @page: the page which is affected
Lukas Czernerd47992f2013-05-21 23:17:23 -04001497 * @offset: start of the range to invalidate
1498 * @length: length of the range to invalidate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001499 *
1500 * block_invalidatepage() is called when all or part of the page has become
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001501 * invalidated by a truncate operation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 *
1503 * block_invalidatepage() does not have to release all buffers, but it must
1504 * ensure that no dirty buffer is left outside @offset and that no I/O
1505 * is underway against any of the blocks which are outside the truncation
1506 * point. Because the caller is about to free (and possibly reuse) those
1507 * blocks on-disk.
1508 */
Lukas Czernerd47992f2013-05-21 23:17:23 -04001509void block_invalidatepage(struct page *page, unsigned int offset,
1510 unsigned int length)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511{
1512 struct buffer_head *head, *bh, *next;
1513 unsigned int curr_off = 0;
Lukas Czernerd47992f2013-05-21 23:17:23 -04001514 unsigned int stop = length + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515
1516 BUG_ON(!PageLocked(page));
1517 if (!page_has_buffers(page))
1518 goto out;
1519
Lukas Czernerd47992f2013-05-21 23:17:23 -04001520 /*
1521 * Check for overflow
1522 */
1523 BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 head = page_buffers(page);
1526 bh = head;
1527 do {
1528 unsigned int next_off = curr_off + bh->b_size;
1529 next = bh->b_this_page;
1530
1531 /*
Lukas Czernerd47992f2013-05-21 23:17:23 -04001532 * Are we still fully in range ?
1533 */
1534 if (next_off > stop)
1535 goto out;
1536
1537 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538 * is this block fully invalidated?
1539 */
1540 if (offset <= curr_off)
1541 discard_buffer(bh);
1542 curr_off = next_off;
1543 bh = next;
1544 } while (bh != head);
1545
1546 /*
1547 * We release buffers only if the entire page is being invalidated.
1548 * The get_block cached value has been unconditionally invalidated,
1549 * so real IO is not possible anymore.
1550 */
1551 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001552 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001554 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555}
1556EXPORT_SYMBOL(block_invalidatepage);
1557
Lukas Czernerd47992f2013-05-21 23:17:23 -04001558
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559/*
1560 * We attach and possibly dirty the buffers atomically wrt
1561 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1562 * is already excluded via the page lock.
1563 */
1564void create_empty_buffers(struct page *page,
1565 unsigned long blocksize, unsigned long b_state)
1566{
1567 struct buffer_head *bh, *head, *tail;
1568
1569 head = alloc_page_buffers(page, blocksize, 1);
1570 bh = head;
1571 do {
1572 bh->b_state |= b_state;
1573 tail = bh;
1574 bh = bh->b_this_page;
1575 } while (bh);
1576 tail->b_this_page = head;
1577
1578 spin_lock(&page->mapping->private_lock);
1579 if (PageUptodate(page) || PageDirty(page)) {
1580 bh = head;
1581 do {
1582 if (PageDirty(page))
1583 set_buffer_dirty(bh);
1584 if (PageUptodate(page))
1585 set_buffer_uptodate(bh);
1586 bh = bh->b_this_page;
1587 } while (bh != head);
1588 }
1589 attach_page_buffers(page, head);
1590 spin_unlock(&page->mapping->private_lock);
1591}
1592EXPORT_SYMBOL(create_empty_buffers);
1593
1594/*
1595 * We are taking a block for data and we don't want any output from any
1596 * buffer-cache aliases starting from return from that function and
1597 * until the moment when something will explicitly mark the buffer
1598 * dirty (hopefully that will not happen until we will free that block ;-)
1599 * We don't even need to mark it not-uptodate - nobody can expect
1600 * anything from a newly allocated buffer anyway. We used to used
1601 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1602 * don't want to mark the alias unmapped, for example - it would confuse
1603 * anyone who might pick it with bread() afterwards...
1604 *
1605 * Also.. Note that bforget() doesn't lock the buffer. So there can
1606 * be writeout I/O going on against recently-freed buffers. We don't
1607 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1608 * only if we really need to. That happens here.
1609 */
1610void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1611{
1612 struct buffer_head *old_bh;
1613
1614 might_sleep();
1615
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001616 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 if (old_bh) {
1618 clear_buffer_dirty(old_bh);
1619 wait_on_buffer(old_bh);
1620 clear_buffer_req(old_bh);
1621 __brelse(old_bh);
1622 }
1623}
1624EXPORT_SYMBOL(unmap_underlying_metadata);
1625
1626/*
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001627 * Size is a power-of-two in the range 512..PAGE_SIZE,
1628 * and the case we care about most is PAGE_SIZE.
1629 *
1630 * So this *could* possibly be written with those
1631 * constraints in mind (relevant mostly if some
1632 * architecture has a slow bit-scan instruction)
1633 */
1634static inline int block_size_bits(unsigned int blocksize)
1635{
1636 return ilog2(blocksize);
1637}
1638
1639static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state)
1640{
1641 BUG_ON(!PageLocked(page));
1642
1643 if (!page_has_buffers(page))
1644 create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state);
1645 return page_buffers(page);
1646}
1647
1648/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001649 * NOTE! All mapped/uptodate combinations are valid:
1650 *
1651 * Mapped Uptodate Meaning
1652 *
1653 * No No "unknown" - must do get_block()
1654 * No Yes "hole" - zero-filled
1655 * Yes No "allocated" - allocated on disk, not read in
1656 * Yes Yes "valid" - allocated and up-to-date in memory.
1657 *
1658 * "Dirty" is valid only with the last case (mapped+uptodate).
1659 */
1660
1661/*
1662 * While block_write_full_page is writing back the dirty buffers under
1663 * the page lock, whoever dirtied the buffers may decide to clean them
1664 * again at any time. We handle that by only looking at the buffer
1665 * state inside lock_buffer().
1666 *
1667 * If block_write_full_page() is called for regular writeback
1668 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1669 * locked buffer. This only can happen if someone has written the buffer
1670 * directly, with submit_bh(). At the address_space level PageWriteback
1671 * prevents this contention from occurring.
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001672 *
1673 * If block_write_full_page() is called with wbc->sync_mode ==
Jens Axboe721a9602011-03-09 11:56:30 +01001674 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
1675 * causes the writes to be flagged as synchronous writes.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676 */
1677static int __block_write_full_page(struct inode *inode, struct page *page,
Chris Mason35c80d52009-04-15 13:22:38 -04001678 get_block_t *get_block, struct writeback_control *wbc,
1679 bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680{
1681 int err;
1682 sector_t block;
1683 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001684 struct buffer_head *bh, *head;
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001685 unsigned int blocksize, bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686 int nr_underway = 0;
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001687 int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
Jens Axboe721a9602011-03-09 11:56:30 +01001688 WRITE_SYNC : WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001689
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001690 head = create_page_buffers(page, inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001691 (1 << BH_Dirty)|(1 << BH_Uptodate));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692
1693 /*
1694 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1695 * here, and the (potentially unmapped) buffers may become dirty at
1696 * any time. If a buffer becomes dirty here after we've inspected it
1697 * then we just miss that fact, and the page stays dirty.
1698 *
1699 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1700 * handle that here by just cleaning them.
1701 */
1702
Linus Torvalds1da177e2005-04-16 15:20:36 -07001703 bh = head;
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001704 blocksize = bh->b_size;
1705 bbits = block_size_bits(blocksize);
1706
1707 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1708 last_block = (i_size_read(inode) - 1) >> bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709
1710 /*
1711 * Get all the dirty buffers mapped to disk addresses and
1712 * handle any aliases from the underlying blockdev's mapping.
1713 */
1714 do {
1715 if (block > last_block) {
1716 /*
1717 * mapped buffers outside i_size will occur, because
1718 * this page can be outside i_size when there is a
1719 * truncate in progress.
1720 */
1721 /*
1722 * The buffer was zeroed by block_write_full_page()
1723 */
1724 clear_buffer_dirty(bh);
1725 set_buffer_uptodate(bh);
Alex Tomas29a814d2008-07-11 19:27:31 -04001726 } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
1727 buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001728 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001729 err = get_block(inode, block, bh, 1);
1730 if (err)
1731 goto recover;
Alex Tomas29a814d2008-07-11 19:27:31 -04001732 clear_buffer_delay(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001733 if (buffer_new(bh)) {
1734 /* blockdev mappings never come here */
1735 clear_buffer_new(bh);
1736 unmap_underlying_metadata(bh->b_bdev,
1737 bh->b_blocknr);
1738 }
1739 }
1740 bh = bh->b_this_page;
1741 block++;
1742 } while (bh != head);
1743
1744 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 if (!buffer_mapped(bh))
1746 continue;
1747 /*
1748 * If it's a fully non-blocking write attempt and we cannot
1749 * lock the buffer then redirty the page. Note that this can
Jens Axboe5b0830c2009-09-23 19:37:09 +02001750 * potentially cause a busy-wait loop from writeback threads
1751 * and kswapd activity, but those code paths have their own
1752 * higher-level throttling.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753 */
Wu Fengguang1b430be2010-10-26 14:21:26 -07001754 if (wbc->sync_mode != WB_SYNC_NONE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001755 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02001756 } else if (!trylock_buffer(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757 redirty_page_for_writepage(wbc, page);
1758 continue;
1759 }
1760 if (test_clear_buffer_dirty(bh)) {
Chris Mason35c80d52009-04-15 13:22:38 -04001761 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 } else {
1763 unlock_buffer(bh);
1764 }
1765 } while ((bh = bh->b_this_page) != head);
1766
1767 /*
1768 * The page and its buffers are protected by PageWriteback(), so we can
1769 * drop the bh refcounts early.
1770 */
1771 BUG_ON(PageWriteback(page));
1772 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773
1774 do {
1775 struct buffer_head *next = bh->b_this_page;
1776 if (buffer_async_write(bh)) {
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001777 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 nr_underway++;
1779 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 bh = next;
1781 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001782 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783
1784 err = 0;
1785done:
1786 if (nr_underway == 0) {
1787 /*
1788 * The page was marked dirty, but the buffers were
1789 * clean. Someone wrote them back by hand with
1790 * ll_rw_block/submit_bh. A rare case.
1791 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001793
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794 /*
1795 * The page and buffer_heads can be released at any time from
1796 * here on.
1797 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 }
1799 return err;
1800
1801recover:
1802 /*
1803 * ENOSPC, or some other error. We may already have added some
1804 * blocks to the file, so we need to write these out to avoid
1805 * exposing stale data.
1806 * The page is currently locked and not marked for writeback
1807 */
1808 bh = head;
1809 /* Recovery: lock and submit the mapped buffers */
1810 do {
Alex Tomas29a814d2008-07-11 19:27:31 -04001811 if (buffer_mapped(bh) && buffer_dirty(bh) &&
1812 !buffer_delay(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001813 lock_buffer(bh);
Chris Mason35c80d52009-04-15 13:22:38 -04001814 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 } else {
1816 /*
1817 * The buffer may have been set dirty during
1818 * attachment to a dirty page.
1819 */
1820 clear_buffer_dirty(bh);
1821 }
1822 } while ((bh = bh->b_this_page) != head);
1823 SetPageError(page);
1824 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001825 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 do {
1828 struct buffer_head *next = bh->b_this_page;
1829 if (buffer_async_write(bh)) {
1830 clear_buffer_dirty(bh);
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001831 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 nr_underway++;
1833 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834 bh = next;
1835 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001836 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837 goto done;
1838}
1839
Nick Pigginafddba42007-10-16 01:25:01 -07001840/*
1841 * If a page has any new buffers, zero them out here, and mark them uptodate
1842 * and dirty so they'll be written out (in order to prevent uninitialised
1843 * block data from leaking). And clear the new bit.
1844 */
1845void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1846{
1847 unsigned int block_start, block_end;
1848 struct buffer_head *head, *bh;
1849
1850 BUG_ON(!PageLocked(page));
1851 if (!page_has_buffers(page))
1852 return;
1853
1854 bh = head = page_buffers(page);
1855 block_start = 0;
1856 do {
1857 block_end = block_start + bh->b_size;
1858
1859 if (buffer_new(bh)) {
1860 if (block_end > from && block_start < to) {
1861 if (!PageUptodate(page)) {
1862 unsigned start, size;
1863
1864 start = max(from, block_start);
1865 size = min(to, block_end) - start;
1866
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001867 zero_user(page, start, size);
Nick Pigginafddba42007-10-16 01:25:01 -07001868 set_buffer_uptodate(bh);
1869 }
1870
1871 clear_buffer_new(bh);
1872 mark_buffer_dirty(bh);
1873 }
1874 }
1875
1876 block_start = block_end;
1877 bh = bh->b_this_page;
1878 } while (bh != head);
1879}
1880EXPORT_SYMBOL(page_zero_new_buffers);
1881
Christoph Hellwigebdec242010-10-06 10:47:23 +02001882int __block_write_begin(struct page *page, loff_t pos, unsigned len,
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001883 get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001884{
Christoph Hellwigebdec242010-10-06 10:47:23 +02001885 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1886 unsigned to = from + len;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001887 struct inode *inode = page->mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001888 unsigned block_start, block_end;
1889 sector_t block;
1890 int err = 0;
1891 unsigned blocksize, bbits;
1892 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1893
1894 BUG_ON(!PageLocked(page));
1895 BUG_ON(from > PAGE_CACHE_SIZE);
1896 BUG_ON(to > PAGE_CACHE_SIZE);
1897 BUG_ON(from > to);
1898
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001899 head = create_page_buffers(page, inode, 0);
1900 blocksize = head->b_size;
1901 bbits = block_size_bits(blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001902
Linus Torvalds1da177e2005-04-16 15:20:36 -07001903 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1904
1905 for(bh = head, block_start = 0; bh != head || !block_start;
1906 block++, block_start=block_end, bh = bh->b_this_page) {
1907 block_end = block_start + blocksize;
1908 if (block_end <= from || block_start >= to) {
1909 if (PageUptodate(page)) {
1910 if (!buffer_uptodate(bh))
1911 set_buffer_uptodate(bh);
1912 }
1913 continue;
1914 }
1915 if (buffer_new(bh))
1916 clear_buffer_new(bh);
1917 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001918 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919 err = get_block(inode, block, bh, 1);
1920 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001921 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923 unmap_underlying_metadata(bh->b_bdev,
1924 bh->b_blocknr);
1925 if (PageUptodate(page)) {
Nick Piggin637aff42007-10-16 01:25:00 -07001926 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001927 set_buffer_uptodate(bh);
Nick Piggin637aff42007-10-16 01:25:00 -07001928 mark_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 continue;
1930 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001931 if (block_end > to || block_start < from)
1932 zero_user_segments(page,
1933 to, block_end,
1934 block_start, from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 continue;
1936 }
1937 }
1938 if (PageUptodate(page)) {
1939 if (!buffer_uptodate(bh))
1940 set_buffer_uptodate(bh);
1941 continue;
1942 }
1943 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08001944 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001945 (block_start < from || block_end > to)) {
1946 ll_rw_block(READ, 1, &bh);
1947 *wait_bh++=bh;
1948 }
1949 }
1950 /*
1951 * If we issued read requests - let them complete.
1952 */
1953 while(wait_bh > wait) {
1954 wait_on_buffer(*--wait_bh);
1955 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001956 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001957 }
Jan Karaf9f07b62011-06-14 00:58:27 +02001958 if (unlikely(err))
Nick Pigginafddba42007-10-16 01:25:01 -07001959 page_zero_new_buffers(page, from, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960 return err;
1961}
Christoph Hellwigebdec242010-10-06 10:47:23 +02001962EXPORT_SYMBOL(__block_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963
1964static int __block_commit_write(struct inode *inode, struct page *page,
1965 unsigned from, unsigned to)
1966{
1967 unsigned block_start, block_end;
1968 int partial = 0;
1969 unsigned blocksize;
1970 struct buffer_head *bh, *head;
1971
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001972 bh = head = page_buffers(page);
1973 blocksize = bh->b_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001975 block_start = 0;
1976 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001977 block_end = block_start + blocksize;
1978 if (block_end <= from || block_start >= to) {
1979 if (!buffer_uptodate(bh))
1980 partial = 1;
1981 } else {
1982 set_buffer_uptodate(bh);
1983 mark_buffer_dirty(bh);
1984 }
Nick Pigginafddba42007-10-16 01:25:01 -07001985 clear_buffer_new(bh);
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001986
1987 block_start = block_end;
1988 bh = bh->b_this_page;
1989 } while (bh != head);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990
1991 /*
1992 * If this is a partial write which happened to make all buffers
1993 * uptodate then we can optimize away a bogus readpage() for
1994 * the next read(). Here we 'discover' whether the page went
1995 * uptodate as a result of this (potentially partial) write.
1996 */
1997 if (!partial)
1998 SetPageUptodate(page);
1999 return 0;
2000}
2001
2002/*
Christoph Hellwig155130a2010-06-04 11:29:58 +02002003 * block_write_begin takes care of the basic task of block allocation and
2004 * bringing partial write blocks uptodate first.
2005 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002006 * The filesystem needs to handle block truncation upon failure.
Nick Pigginafddba42007-10-16 01:25:01 -07002007 */
Christoph Hellwig155130a2010-06-04 11:29:58 +02002008int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
2009 unsigned flags, struct page **pagep, get_block_t *get_block)
Nick Pigginafddba42007-10-16 01:25:01 -07002010{
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002011 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
Nick Pigginafddba42007-10-16 01:25:01 -07002012 struct page *page;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002013 int status;
Nick Pigginafddba42007-10-16 01:25:01 -07002014
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002015 page = grab_cache_page_write_begin(mapping, index, flags);
2016 if (!page)
2017 return -ENOMEM;
Nick Pigginafddba42007-10-16 01:25:01 -07002018
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002019 status = __block_write_begin(page, pos, len, get_block);
Nick Pigginafddba42007-10-16 01:25:01 -07002020 if (unlikely(status)) {
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002021 unlock_page(page);
2022 page_cache_release(page);
2023 page = NULL;
Nick Pigginafddba42007-10-16 01:25:01 -07002024 }
2025
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002026 *pagep = page;
Nick Pigginafddba42007-10-16 01:25:01 -07002027 return status;
2028}
2029EXPORT_SYMBOL(block_write_begin);
2030
2031int block_write_end(struct file *file, struct address_space *mapping,
2032 loff_t pos, unsigned len, unsigned copied,
2033 struct page *page, void *fsdata)
2034{
2035 struct inode *inode = mapping->host;
2036 unsigned start;
2037
2038 start = pos & (PAGE_CACHE_SIZE - 1);
2039
2040 if (unlikely(copied < len)) {
2041 /*
2042 * The buffers that were written will now be uptodate, so we
2043 * don't have to worry about a readpage reading them and
2044 * overwriting a partial write. However if we have encountered
2045 * a short write and only partially written into a buffer, it
2046 * will not be marked uptodate, so a readpage might come in and
2047 * destroy our partial write.
2048 *
2049 * Do the simplest thing, and just treat any short write to a
2050 * non uptodate page as a zero-length write, and force the
2051 * caller to redo the whole thing.
2052 */
2053 if (!PageUptodate(page))
2054 copied = 0;
2055
2056 page_zero_new_buffers(page, start+copied, start+len);
2057 }
2058 flush_dcache_page(page);
2059
2060 /* This could be a short (even 0-length) commit */
2061 __block_commit_write(inode, page, start, start+copied);
2062
2063 return copied;
2064}
2065EXPORT_SYMBOL(block_write_end);
2066
2067int generic_write_end(struct file *file, struct address_space *mapping,
2068 loff_t pos, unsigned len, unsigned copied,
2069 struct page *page, void *fsdata)
2070{
2071 struct inode *inode = mapping->host;
Jan Kara90a80202014-10-01 21:49:18 -04002072 loff_t old_size = inode->i_size;
Jan Karac7d206b2008-07-11 19:27:31 -04002073 int i_size_changed = 0;
Nick Pigginafddba42007-10-16 01:25:01 -07002074
2075 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2076
2077 /*
2078 * No need to use i_size_read() here, the i_size
2079 * cannot change under us because we hold i_mutex.
2080 *
2081 * But it's important to update i_size while still holding page lock:
2082 * page writeout could otherwise come in and zero beyond i_size.
2083 */
2084 if (pos+copied > inode->i_size) {
2085 i_size_write(inode, pos+copied);
Jan Karac7d206b2008-07-11 19:27:31 -04002086 i_size_changed = 1;
Nick Pigginafddba42007-10-16 01:25:01 -07002087 }
2088
2089 unlock_page(page);
2090 page_cache_release(page);
2091
Jan Kara90a80202014-10-01 21:49:18 -04002092 if (old_size < pos)
2093 pagecache_isize_extended(inode, old_size, pos);
Jan Karac7d206b2008-07-11 19:27:31 -04002094 /*
2095 * Don't mark the inode dirty under page lock. First, it unnecessarily
2096 * makes the holding time of page lock longer. Second, it forces lock
2097 * ordering of page lock and transaction start for journaling
2098 * filesystems.
2099 */
2100 if (i_size_changed)
2101 mark_inode_dirty(inode);
2102
Nick Pigginafddba42007-10-16 01:25:01 -07002103 return copied;
2104}
2105EXPORT_SYMBOL(generic_write_end);
2106
2107/*
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002108 * block_is_partially_uptodate checks whether buffers within a page are
2109 * uptodate or not.
2110 *
2111 * Returns true if all buffers which correspond to a file portion
2112 * we want to read are uptodate.
2113 */
Al Viroc186afb42014-02-02 21:16:54 -05002114int block_is_partially_uptodate(struct page *page, unsigned long from,
2115 unsigned long count)
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002116{
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002117 unsigned block_start, block_end, blocksize;
2118 unsigned to;
2119 struct buffer_head *bh, *head;
2120 int ret = 1;
2121
2122 if (!page_has_buffers(page))
2123 return 0;
2124
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002125 head = page_buffers(page);
2126 blocksize = head->b_size;
Al Viroc186afb42014-02-02 21:16:54 -05002127 to = min_t(unsigned, PAGE_CACHE_SIZE - from, count);
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002128 to = from + to;
2129 if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2130 return 0;
2131
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002132 bh = head;
2133 block_start = 0;
2134 do {
2135 block_end = block_start + blocksize;
2136 if (block_end > from && block_start < to) {
2137 if (!buffer_uptodate(bh)) {
2138 ret = 0;
2139 break;
2140 }
2141 if (block_end >= to)
2142 break;
2143 }
2144 block_start = block_end;
2145 bh = bh->b_this_page;
2146 } while (bh != head);
2147
2148 return ret;
2149}
2150EXPORT_SYMBOL(block_is_partially_uptodate);
2151
2152/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153 * Generic "read page" function for block devices that have the normal
2154 * get_block functionality. This is most of the block device filesystems.
2155 * Reads the page asynchronously --- the unlock_buffer() and
2156 * set/clear_buffer_uptodate() functions propagate buffer state into the
2157 * page struct once IO has completed.
2158 */
2159int block_read_full_page(struct page *page, get_block_t *get_block)
2160{
2161 struct inode *inode = page->mapping->host;
2162 sector_t iblock, lblock;
2163 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002164 unsigned int blocksize, bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 int nr, i;
2166 int fully_mapped = 1;
2167
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002168 head = create_page_buffers(page, inode, 0);
2169 blocksize = head->b_size;
2170 bbits = block_size_bits(blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002172 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
2173 lblock = (i_size_read(inode)+blocksize-1) >> bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 bh = head;
2175 nr = 0;
2176 i = 0;
2177
2178 do {
2179 if (buffer_uptodate(bh))
2180 continue;
2181
2182 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002183 int err = 0;
2184
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 fully_mapped = 0;
2186 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002187 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002188 err = get_block(inode, iblock, bh, 0);
2189 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002190 SetPageError(page);
2191 }
2192 if (!buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002193 zero_user(page, i * blocksize, blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002194 if (!err)
2195 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002196 continue;
2197 }
2198 /*
2199 * get_block() might have updated the buffer
2200 * synchronously
2201 */
2202 if (buffer_uptodate(bh))
2203 continue;
2204 }
2205 arr[nr++] = bh;
2206 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2207
2208 if (fully_mapped)
2209 SetPageMappedToDisk(page);
2210
2211 if (!nr) {
2212 /*
2213 * All buffers are uptodate - we can set the page uptodate
2214 * as well. But not if get_block() returned an error.
2215 */
2216 if (!PageError(page))
2217 SetPageUptodate(page);
2218 unlock_page(page);
2219 return 0;
2220 }
2221
2222 /* Stage two: lock the buffers */
2223 for (i = 0; i < nr; i++) {
2224 bh = arr[i];
2225 lock_buffer(bh);
2226 mark_buffer_async_read(bh);
2227 }
2228
2229 /*
2230 * Stage 3: start the IO. Check for uptodateness
2231 * inside the buffer lock in case another process reading
2232 * the underlying blockdev brought it uptodate (the sct fix).
2233 */
2234 for (i = 0; i < nr; i++) {
2235 bh = arr[i];
2236 if (buffer_uptodate(bh))
2237 end_buffer_async_read(bh, 1);
2238 else
2239 submit_bh(READ, bh);
2240 }
2241 return 0;
2242}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002243EXPORT_SYMBOL(block_read_full_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002244
2245/* utility function for filesystems that need to do work on expanding
Nick Piggin89e10782007-10-16 01:25:07 -07002246 * truncates. Uses filesystem pagecache writes to allow the filesystem to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247 * deal with the hole.
2248 */
Nick Piggin89e10782007-10-16 01:25:07 -07002249int generic_cont_expand_simple(struct inode *inode, loff_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250{
2251 struct address_space *mapping = inode->i_mapping;
2252 struct page *page;
Nick Piggin89e10782007-10-16 01:25:07 -07002253 void *fsdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002254 int err;
2255
npiggin@suse.dec08d3b02009-08-21 02:35:06 +10002256 err = inode_newsize_ok(inode, size);
2257 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 goto out;
2259
Nick Piggin89e10782007-10-16 01:25:07 -07002260 err = pagecache_write_begin(NULL, mapping, size, 0,
2261 AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2262 &page, &fsdata);
2263 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 goto out;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002265
Nick Piggin89e10782007-10-16 01:25:07 -07002266 err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2267 BUG_ON(err > 0);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002268
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269out:
2270 return err;
2271}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002272EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273
Adrian Bunkf1e3af72008-04-29 00:59:01 -07002274static int cont_expand_zero(struct file *file, struct address_space *mapping,
2275 loff_t pos, loff_t *bytes)
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002276{
Nick Piggin89e10782007-10-16 01:25:07 -07002277 struct inode *inode = mapping->host;
2278 unsigned blocksize = 1 << inode->i_blkbits;
2279 struct page *page;
2280 void *fsdata;
2281 pgoff_t index, curidx;
2282 loff_t curpos;
2283 unsigned zerofrom, offset, len;
2284 int err = 0;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002285
Nick Piggin89e10782007-10-16 01:25:07 -07002286 index = pos >> PAGE_CACHE_SHIFT;
2287 offset = pos & ~PAGE_CACHE_MASK;
2288
2289 while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2290 zerofrom = curpos & ~PAGE_CACHE_MASK;
2291 if (zerofrom & (blocksize-1)) {
2292 *bytes |= (blocksize-1);
2293 (*bytes)++;
2294 }
2295 len = PAGE_CACHE_SIZE - zerofrom;
2296
2297 err = pagecache_write_begin(file, mapping, curpos, len,
2298 AOP_FLAG_UNINTERRUPTIBLE,
2299 &page, &fsdata);
2300 if (err)
2301 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002302 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002303 err = pagecache_write_end(file, mapping, curpos, len, len,
2304 page, fsdata);
2305 if (err < 0)
2306 goto out;
2307 BUG_ON(err != len);
2308 err = 0;
OGAWA Hirofumi061e9742008-04-28 02:16:28 -07002309
2310 balance_dirty_pages_ratelimited(mapping);
Mikulas Patockac2ca0fc2014-07-27 13:00:41 -04002311
2312 if (unlikely(fatal_signal_pending(current))) {
2313 err = -EINTR;
2314 goto out;
2315 }
Nick Piggin89e10782007-10-16 01:25:07 -07002316 }
2317
2318 /* page covers the boundary, find the boundary offset */
2319 if (index == curidx) {
2320 zerofrom = curpos & ~PAGE_CACHE_MASK;
2321 /* if we will expand the thing last block will be filled */
2322 if (offset <= zerofrom) {
2323 goto out;
2324 }
2325 if (zerofrom & (blocksize-1)) {
2326 *bytes |= (blocksize-1);
2327 (*bytes)++;
2328 }
2329 len = offset - zerofrom;
2330
2331 err = pagecache_write_begin(file, mapping, curpos, len,
2332 AOP_FLAG_UNINTERRUPTIBLE,
2333 &page, &fsdata);
2334 if (err)
2335 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002336 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002337 err = pagecache_write_end(file, mapping, curpos, len, len,
2338 page, fsdata);
2339 if (err < 0)
2340 goto out;
2341 BUG_ON(err != len);
2342 err = 0;
2343 }
2344out:
2345 return err;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002346}
2347
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348/*
2349 * For moronic filesystems that do not allow holes in file.
2350 * We may have to extend the file.
2351 */
Christoph Hellwig282dc172010-06-04 11:29:55 +02002352int cont_write_begin(struct file *file, struct address_space *mapping,
Nick Piggin89e10782007-10-16 01:25:07 -07002353 loff_t pos, unsigned len, unsigned flags,
2354 struct page **pagep, void **fsdata,
2355 get_block_t *get_block, loff_t *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002357 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002358 unsigned blocksize = 1 << inode->i_blkbits;
Nick Piggin89e10782007-10-16 01:25:07 -07002359 unsigned zerofrom;
2360 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361
Nick Piggin89e10782007-10-16 01:25:07 -07002362 err = cont_expand_zero(file, mapping, pos, bytes);
2363 if (err)
Christoph Hellwig155130a2010-06-04 11:29:58 +02002364 return err;
Nick Piggin89e10782007-10-16 01:25:07 -07002365
2366 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2367 if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2368 *bytes |= (blocksize-1);
2369 (*bytes)++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 }
2371
Christoph Hellwig155130a2010-06-04 11:29:58 +02002372 return block_write_begin(mapping, pos, len, flags, pagep, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002374EXPORT_SYMBOL(cont_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002375
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376int block_commit_write(struct page *page, unsigned from, unsigned to)
2377{
2378 struct inode *inode = page->mapping->host;
2379 __block_commit_write(inode,page,from,to);
2380 return 0;
2381}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002382EXPORT_SYMBOL(block_commit_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383
David Chinner54171692007-07-19 17:39:55 +10002384/*
2385 * block_page_mkwrite() is not allowed to change the file size as it gets
2386 * called from a page fault handler when a page is first dirtied. Hence we must
2387 * be careful to check for EOF conditions here. We set the page up correctly
2388 * for a written page which means we get ENOSPC checking when writing into
2389 * holes and correct delalloc and unwritten extent mapping on filesystems that
2390 * support these features.
2391 *
2392 * We are not allowed to take the i_mutex here so we have to play games to
2393 * protect against truncate races as the page could now be beyond EOF. Because
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002394 * truncate writes the inode size before removing pages, once we have the
David Chinner54171692007-07-19 17:39:55 +10002395 * page lock we can determine safely if the page is beyond EOF. If it is not
2396 * beyond EOF, then the page is guaranteed safe against truncation until we
2397 * unlock the page.
Jan Karaea13a862011-05-24 00:23:35 +02002398 *
Jan Kara14da9202012-06-12 16:20:37 +02002399 * Direct callers of this function should protect against filesystem freezing
2400 * using sb_start_write() - sb_end_write() functions.
David Chinner54171692007-07-19 17:39:55 +10002401 */
Jan Kara24da4fa2011-05-24 00:23:34 +02002402int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2403 get_block_t get_block)
David Chinner54171692007-07-19 17:39:55 +10002404{
Nick Pigginc2ec1752009-03-31 15:23:21 -07002405 struct page *page = vmf->page;
Al Viro496ad9a2013-01-23 17:07:38 -05002406 struct inode *inode = file_inode(vma->vm_file);
David Chinner54171692007-07-19 17:39:55 +10002407 unsigned long end;
2408 loff_t size;
Jan Kara24da4fa2011-05-24 00:23:34 +02002409 int ret;
David Chinner54171692007-07-19 17:39:55 +10002410
2411 lock_page(page);
2412 size = i_size_read(inode);
2413 if ((page->mapping != inode->i_mapping) ||
Nick Piggin18336332007-07-20 00:31:45 -07002414 (page_offset(page) > size)) {
Jan Kara24da4fa2011-05-24 00:23:34 +02002415 /* We overload EFAULT to mean page got truncated */
2416 ret = -EFAULT;
2417 goto out_unlock;
David Chinner54171692007-07-19 17:39:55 +10002418 }
2419
2420 /* page is wholly or partially inside EOF */
2421 if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2422 end = size & ~PAGE_CACHE_MASK;
2423 else
2424 end = PAGE_CACHE_SIZE;
2425
Christoph Hellwigebdec242010-10-06 10:47:23 +02002426 ret = __block_write_begin(page, 0, end, get_block);
David Chinner54171692007-07-19 17:39:55 +10002427 if (!ret)
2428 ret = block_commit_write(page, 0, end);
2429
Jan Kara24da4fa2011-05-24 00:23:34 +02002430 if (unlikely(ret < 0))
2431 goto out_unlock;
Jan Karaea13a862011-05-24 00:23:35 +02002432 set_page_dirty(page);
Darrick J. Wong1d1d1a72013-02-21 16:42:51 -08002433 wait_for_stable_page(page);
Jan Kara24da4fa2011-05-24 00:23:34 +02002434 return 0;
2435out_unlock:
2436 unlock_page(page);
David Chinner54171692007-07-19 17:39:55 +10002437 return ret;
2438}
Jan Kara24da4fa2011-05-24 00:23:34 +02002439EXPORT_SYMBOL(__block_page_mkwrite);
2440
2441int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2442 get_block_t get_block)
2443{
Jan Karaea13a862011-05-24 00:23:35 +02002444 int ret;
Al Viro496ad9a2013-01-23 17:07:38 -05002445 struct super_block *sb = file_inode(vma->vm_file)->i_sb;
Jan Kara24da4fa2011-05-24 00:23:34 +02002446
Jan Kara14da9202012-06-12 16:20:37 +02002447 sb_start_pagefault(sb);
Theodore Ts'o041bbb6d2012-09-30 23:04:56 -04002448
2449 /*
2450 * Update file times before taking page lock. We may end up failing the
2451 * fault so this update may be superfluous but who really cares...
2452 */
2453 file_update_time(vma->vm_file);
2454
Jan Karaea13a862011-05-24 00:23:35 +02002455 ret = __block_page_mkwrite(vma, vmf, get_block);
Jan Kara14da9202012-06-12 16:20:37 +02002456 sb_end_pagefault(sb);
Jan Kara24da4fa2011-05-24 00:23:34 +02002457 return block_page_mkwrite_return(ret);
2458}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002459EXPORT_SYMBOL(block_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002460
2461/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002462 * nobh_write_begin()'s prereads are special: the buffer_heads are freed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002463 * immediately, while under the page lock. So it needs a special end_io
2464 * handler which does not touch the bh after unlocking it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002465 */
2466static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2467{
Dmitry Monakhov68671f32007-10-16 01:24:47 -07002468 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469}
2470
2471/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002472 * Attach the singly-linked list of buffers created by nobh_write_begin, to
2473 * the page (converting it to circular linked list and taking care of page
2474 * dirty races).
2475 */
2476static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2477{
2478 struct buffer_head *bh;
2479
2480 BUG_ON(!PageLocked(page));
2481
2482 spin_lock(&page->mapping->private_lock);
2483 bh = head;
2484 do {
2485 if (PageDirty(page))
2486 set_buffer_dirty(bh);
2487 if (!bh->b_this_page)
2488 bh->b_this_page = head;
2489 bh = bh->b_this_page;
2490 } while (bh != head);
2491 attach_page_buffers(page, head);
2492 spin_unlock(&page->mapping->private_lock);
2493}
2494
2495/*
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002496 * On entry, the page is fully not uptodate.
2497 * On exit the page is fully uptodate in the areas outside (from,to)
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002498 * The filesystem needs to handle block truncation upon failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002499 */
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002500int nobh_write_begin(struct address_space *mapping,
Nick Piggin03158cd2007-10-16 01:25:25 -07002501 loff_t pos, unsigned len, unsigned flags,
2502 struct page **pagep, void **fsdata,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002503 get_block_t *get_block)
2504{
Nick Piggin03158cd2007-10-16 01:25:25 -07002505 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002506 const unsigned blkbits = inode->i_blkbits;
2507 const unsigned blocksize = 1 << blkbits;
Nick Piggina4b06722007-10-16 01:24:48 -07002508 struct buffer_head *head, *bh;
Nick Piggin03158cd2007-10-16 01:25:25 -07002509 struct page *page;
2510 pgoff_t index;
2511 unsigned from, to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512 unsigned block_in_page;
Nick Piggina4b06722007-10-16 01:24:48 -07002513 unsigned block_start, block_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514 sector_t block_in_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515 int nr_reads = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516 int ret = 0;
2517 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518
Nick Piggin03158cd2007-10-16 01:25:25 -07002519 index = pos >> PAGE_CACHE_SHIFT;
2520 from = pos & (PAGE_CACHE_SIZE - 1);
2521 to = from + len;
2522
Nick Piggin54566b22009-01-04 12:00:53 -08002523 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Piggin03158cd2007-10-16 01:25:25 -07002524 if (!page)
2525 return -ENOMEM;
2526 *pagep = page;
2527 *fsdata = NULL;
2528
2529 if (page_has_buffers(page)) {
Namhyung Kim309f77a2010-10-25 15:01:12 +09002530 ret = __block_write_begin(page, pos, len, get_block);
2531 if (unlikely(ret))
2532 goto out_release;
2533 return ret;
Nick Piggin03158cd2007-10-16 01:25:25 -07002534 }
Nick Piggina4b06722007-10-16 01:24:48 -07002535
Linus Torvalds1da177e2005-04-16 15:20:36 -07002536 if (PageMappedToDisk(page))
2537 return 0;
2538
Nick Piggina4b06722007-10-16 01:24:48 -07002539 /*
2540 * Allocate buffers so that we can keep track of state, and potentially
2541 * attach them to the page if an error occurs. In the common case of
2542 * no error, they will just be freed again without ever being attached
2543 * to the page (which is all OK, because we're under the page lock).
2544 *
2545 * Be careful: the buffer linked list is a NULL terminated one, rather
2546 * than the circular one we're used to.
2547 */
2548 head = alloc_page_buffers(page, blocksize, 0);
Nick Piggin03158cd2007-10-16 01:25:25 -07002549 if (!head) {
2550 ret = -ENOMEM;
2551 goto out_release;
2552 }
Nick Piggina4b06722007-10-16 01:24:48 -07002553
Linus Torvalds1da177e2005-04-16 15:20:36 -07002554 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555
2556 /*
2557 * We loop across all blocks in the page, whether or not they are
2558 * part of the affected region. This is so we can discover if the
2559 * page is fully mapped-to-disk.
2560 */
Nick Piggina4b06722007-10-16 01:24:48 -07002561 for (block_start = 0, block_in_page = 0, bh = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562 block_start < PAGE_CACHE_SIZE;
Nick Piggina4b06722007-10-16 01:24:48 -07002563 block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002564 int create;
2565
Nick Piggina4b06722007-10-16 01:24:48 -07002566 block_end = block_start + blocksize;
2567 bh->b_state = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 create = 1;
2569 if (block_start >= to)
2570 create = 0;
2571 ret = get_block(inode, block_in_file + block_in_page,
Nick Piggina4b06722007-10-16 01:24:48 -07002572 bh, create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573 if (ret)
2574 goto failed;
Nick Piggina4b06722007-10-16 01:24:48 -07002575 if (!buffer_mapped(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002576 is_mapped_to_disk = 0;
Nick Piggina4b06722007-10-16 01:24:48 -07002577 if (buffer_new(bh))
2578 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2579 if (PageUptodate(page)) {
2580 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581 continue;
Nick Piggina4b06722007-10-16 01:24:48 -07002582 }
2583 if (buffer_new(bh) || !buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002584 zero_user_segments(page, block_start, from,
2585 to, block_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002586 continue;
2587 }
Nick Piggina4b06722007-10-16 01:24:48 -07002588 if (buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002589 continue; /* reiserfs does this */
2590 if (block_start < from || block_end > to) {
Nick Piggina4b06722007-10-16 01:24:48 -07002591 lock_buffer(bh);
2592 bh->b_end_io = end_buffer_read_nobh;
2593 submit_bh(READ, bh);
2594 nr_reads++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595 }
2596 }
2597
2598 if (nr_reads) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 /*
2600 * The page is locked, so these buffers are protected from
2601 * any VM or truncate activity. Hence we don't need to care
2602 * for the buffer_head refcounts.
2603 */
Nick Piggina4b06722007-10-16 01:24:48 -07002604 for (bh = head; bh; bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002605 wait_on_buffer(bh);
2606 if (!buffer_uptodate(bh))
2607 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002608 }
2609 if (ret)
2610 goto failed;
2611 }
2612
2613 if (is_mapped_to_disk)
2614 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002615
Nick Piggin03158cd2007-10-16 01:25:25 -07002616 *fsdata = head; /* to be released by nobh_write_end */
Nick Piggina4b06722007-10-16 01:24:48 -07002617
Linus Torvalds1da177e2005-04-16 15:20:36 -07002618 return 0;
2619
2620failed:
Nick Piggin03158cd2007-10-16 01:25:25 -07002621 BUG_ON(!ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002622 /*
Nick Piggina4b06722007-10-16 01:24:48 -07002623 * Error recovery is a bit difficult. We need to zero out blocks that
2624 * were newly allocated, and dirty them to ensure they get written out.
2625 * Buffers need to be attached to the page at this point, otherwise
2626 * the handling of potential IO errors during writeout would be hard
2627 * (could try doing synchronous writeout, but what if that fails too?)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002628 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002629 attach_nobh_buffers(page, head);
2630 page_zero_new_buffers(page, from, to);
Nick Piggina4b06722007-10-16 01:24:48 -07002631
Nick Piggin03158cd2007-10-16 01:25:25 -07002632out_release:
2633 unlock_page(page);
2634 page_cache_release(page);
2635 *pagep = NULL;
Nick Piggina4b06722007-10-16 01:24:48 -07002636
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002637 return ret;
2638}
Nick Piggin03158cd2007-10-16 01:25:25 -07002639EXPORT_SYMBOL(nobh_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002640
Nick Piggin03158cd2007-10-16 01:25:25 -07002641int nobh_write_end(struct file *file, struct address_space *mapping,
2642 loff_t pos, unsigned len, unsigned copied,
2643 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644{
2645 struct inode *inode = page->mapping->host;
Nick Pigginefdc3132007-10-21 06:57:41 +02002646 struct buffer_head *head = fsdata;
Nick Piggin03158cd2007-10-16 01:25:25 -07002647 struct buffer_head *bh;
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002648 BUG_ON(fsdata != NULL && page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002649
Dave Kleikampd4cf1092009-02-06 14:59:26 -06002650 if (unlikely(copied < len) && head)
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002651 attach_nobh_buffers(page, head);
2652 if (page_has_buffers(page))
2653 return generic_write_end(file, mapping, pos, len,
2654 copied, page, fsdata);
Nick Piggina4b06722007-10-16 01:24:48 -07002655
Nick Piggin22c8ca72007-02-20 13:58:09 -08002656 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657 set_page_dirty(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002658 if (pos+copied > inode->i_size) {
2659 i_size_write(inode, pos+copied);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002660 mark_inode_dirty(inode);
2661 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002662
2663 unlock_page(page);
2664 page_cache_release(page);
2665
Nick Piggin03158cd2007-10-16 01:25:25 -07002666 while (head) {
2667 bh = head;
2668 head = head->b_this_page;
2669 free_buffer_head(bh);
2670 }
2671
2672 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673}
Nick Piggin03158cd2007-10-16 01:25:25 -07002674EXPORT_SYMBOL(nobh_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002675
2676/*
2677 * nobh_writepage() - based on block_full_write_page() except
2678 * that it tries to operate without attaching bufferheads to
2679 * the page.
2680 */
2681int nobh_writepage(struct page *page, get_block_t *get_block,
2682 struct writeback_control *wbc)
2683{
2684 struct inode * const inode = page->mapping->host;
2685 loff_t i_size = i_size_read(inode);
2686 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2687 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002688 int ret;
2689
2690 /* Is the page fully inside i_size? */
2691 if (page->index < end_index)
2692 goto out;
2693
2694 /* Is the page fully outside i_size? (truncate in progress) */
2695 offset = i_size & (PAGE_CACHE_SIZE-1);
2696 if (page->index >= end_index+1 || !offset) {
2697 /*
2698 * The page may have dirty, unmapped buffers. For example,
2699 * they may have been added in ext3_writepage(). Make them
2700 * freeable here, so the page does not leak.
2701 */
2702#if 0
2703 /* Not really sure about this - do we need this ? */
2704 if (page->mapping->a_ops->invalidatepage)
2705 page->mapping->a_ops->invalidatepage(page, offset);
2706#endif
2707 unlock_page(page);
2708 return 0; /* don't care */
2709 }
2710
2711 /*
2712 * The page straddles i_size. It must be zeroed out on each and every
2713 * writepage invocation because it may be mmapped. "A file is mapped
2714 * in multiples of the page size. For a file that is not a multiple of
2715 * the page size, the remaining memory is zeroed when mapped, and
2716 * writes to that region are not written out to the file."
2717 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002718 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002719out:
2720 ret = mpage_writepage(page, get_block, wbc);
2721 if (ret == -EAGAIN)
Chris Mason35c80d52009-04-15 13:22:38 -04002722 ret = __block_write_full_page(inode, page, get_block, wbc,
2723 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002724 return ret;
2725}
2726EXPORT_SYMBOL(nobh_writepage);
2727
Nick Piggin03158cd2007-10-16 01:25:25 -07002728int nobh_truncate_page(struct address_space *mapping,
2729 loff_t from, get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002730{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002731 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2732 unsigned offset = from & (PAGE_CACHE_SIZE-1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002733 unsigned blocksize;
2734 sector_t iblock;
2735 unsigned length, pos;
2736 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002737 struct page *page;
Nick Piggin03158cd2007-10-16 01:25:25 -07002738 struct buffer_head map_bh;
2739 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002740
Nick Piggin03158cd2007-10-16 01:25:25 -07002741 blocksize = 1 << inode->i_blkbits;
2742 length = offset & (blocksize - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002743
Nick Piggin03158cd2007-10-16 01:25:25 -07002744 /* Block boundary? Nothing to do */
2745 if (!length)
2746 return 0;
2747
2748 length = blocksize - length;
2749 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2750
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751 page = grab_cache_page(mapping, index);
Nick Piggin03158cd2007-10-16 01:25:25 -07002752 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002753 if (!page)
2754 goto out;
2755
Nick Piggin03158cd2007-10-16 01:25:25 -07002756 if (page_has_buffers(page)) {
2757has_buffers:
2758 unlock_page(page);
2759 page_cache_release(page);
2760 return block_truncate_page(mapping, from, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002761 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002762
2763 /* Find the buffer that contains "offset" */
2764 pos = blocksize;
2765 while (offset >= pos) {
2766 iblock++;
2767 pos += blocksize;
2768 }
2769
Theodore Ts'o460bcf52009-05-12 07:37:56 -04002770 map_bh.b_size = blocksize;
2771 map_bh.b_state = 0;
Nick Piggin03158cd2007-10-16 01:25:25 -07002772 err = get_block(inode, iblock, &map_bh, 0);
2773 if (err)
2774 goto unlock;
2775 /* unmapped? It's a hole - nothing to do */
2776 if (!buffer_mapped(&map_bh))
2777 goto unlock;
2778
2779 /* Ok, it's mapped. Make sure it's up-to-date */
2780 if (!PageUptodate(page)) {
2781 err = mapping->a_ops->readpage(NULL, page);
2782 if (err) {
2783 page_cache_release(page);
2784 goto out;
2785 }
2786 lock_page(page);
2787 if (!PageUptodate(page)) {
2788 err = -EIO;
2789 goto unlock;
2790 }
2791 if (page_has_buffers(page))
2792 goto has_buffers;
2793 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002794 zero_user(page, offset, length);
Nick Piggin03158cd2007-10-16 01:25:25 -07002795 set_page_dirty(page);
2796 err = 0;
2797
2798unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799 unlock_page(page);
2800 page_cache_release(page);
2801out:
Nick Piggin03158cd2007-10-16 01:25:25 -07002802 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803}
2804EXPORT_SYMBOL(nobh_truncate_page);
2805
2806int block_truncate_page(struct address_space *mapping,
2807 loff_t from, get_block_t *get_block)
2808{
2809 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2810 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2811 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002812 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002813 unsigned length, pos;
2814 struct inode *inode = mapping->host;
2815 struct page *page;
2816 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002817 int err;
2818
2819 blocksize = 1 << inode->i_blkbits;
2820 length = offset & (blocksize - 1);
2821
2822 /* Block boundary? Nothing to do */
2823 if (!length)
2824 return 0;
2825
2826 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002827 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002828
2829 page = grab_cache_page(mapping, index);
2830 err = -ENOMEM;
2831 if (!page)
2832 goto out;
2833
2834 if (!page_has_buffers(page))
2835 create_empty_buffers(page, blocksize, 0);
2836
2837 /* Find the buffer that contains "offset" */
2838 bh = page_buffers(page);
2839 pos = blocksize;
2840 while (offset >= pos) {
2841 bh = bh->b_this_page;
2842 iblock++;
2843 pos += blocksize;
2844 }
2845
2846 err = 0;
2847 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002848 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002849 err = get_block(inode, iblock, bh, 0);
2850 if (err)
2851 goto unlock;
2852 /* unmapped? It's a hole - nothing to do */
2853 if (!buffer_mapped(bh))
2854 goto unlock;
2855 }
2856
2857 /* Ok, it's mapped. Make sure it's up-to-date */
2858 if (PageUptodate(page))
2859 set_buffer_uptodate(bh);
2860
David Chinner33a266d2007-02-12 00:51:41 -08002861 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002862 err = -EIO;
2863 ll_rw_block(READ, 1, &bh);
2864 wait_on_buffer(bh);
2865 /* Uhhuh. Read error. Complain and punt. */
2866 if (!buffer_uptodate(bh))
2867 goto unlock;
2868 }
2869
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002870 zero_user(page, offset, length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871 mark_buffer_dirty(bh);
2872 err = 0;
2873
2874unlock:
2875 unlock_page(page);
2876 page_cache_release(page);
2877out:
2878 return err;
2879}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002880EXPORT_SYMBOL(block_truncate_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002881
2882/*
2883 * The generic ->writepage function for buffer-backed address_spaces
2884 */
Matthew Wilcox1b938c02014-06-04 16:07:43 -07002885int block_write_full_page(struct page *page, get_block_t *get_block,
2886 struct writeback_control *wbc)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002887{
2888 struct inode * const inode = page->mapping->host;
2889 loff_t i_size = i_size_read(inode);
2890 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2891 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002892
2893 /* Is the page fully inside i_size? */
2894 if (page->index < end_index)
Chris Mason35c80d52009-04-15 13:22:38 -04002895 return __block_write_full_page(inode, page, get_block, wbc,
Matthew Wilcox1b938c02014-06-04 16:07:43 -07002896 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002897
2898 /* Is the page fully outside i_size? (truncate in progress) */
2899 offset = i_size & (PAGE_CACHE_SIZE-1);
2900 if (page->index >= end_index+1 || !offset) {
2901 /*
2902 * The page may have dirty, unmapped buffers. For example,
2903 * they may have been added in ext3_writepage(). Make them
2904 * freeable here, so the page does not leak.
2905 */
Lukas Czernerd47992f2013-05-21 23:17:23 -04002906 do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002907 unlock_page(page);
2908 return 0; /* don't care */
2909 }
2910
2911 /*
2912 * The page straddles i_size. It must be zeroed out on each and every
Adam Buchbinder2a61aa42009-12-11 16:35:40 -05002913 * writepage invocation because it may be mmapped. "A file is mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002914 * in multiples of the page size. For a file that is not a multiple of
2915 * the page size, the remaining memory is zeroed when mapped, and
2916 * writes to that region are not written out to the file."
2917 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002918 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Matthew Wilcox1b938c02014-06-04 16:07:43 -07002919 return __block_write_full_page(inode, page, get_block, wbc,
2920 end_buffer_async_write);
Chris Mason35c80d52009-04-15 13:22:38 -04002921}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002922EXPORT_SYMBOL(block_write_full_page);
Chris Mason35c80d52009-04-15 13:22:38 -04002923
Linus Torvalds1da177e2005-04-16 15:20:36 -07002924sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2925 get_block_t *get_block)
2926{
2927 struct buffer_head tmp;
2928 struct inode *inode = mapping->host;
2929 tmp.b_state = 0;
2930 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002931 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002932 get_block(inode, block, &tmp, 0);
2933 return tmp.b_blocknr;
2934}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002935EXPORT_SYMBOL(generic_block_bmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002936
NeilBrown6712ecf2007-09-27 12:47:43 +02002937static void end_bio_bh_io_sync(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938{
2939 struct buffer_head *bh = bio->bi_private;
2940
Linus Torvalds1da177e2005-04-16 15:20:36 -07002941 if (err == -EOPNOTSUPP) {
2942 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002943 }
2944
Keith Mannthey08bafc02008-11-25 10:24:35 +01002945 if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2946 set_bit(BH_Quiet, &bh->b_state);
2947
Linus Torvalds1da177e2005-04-16 15:20:36 -07002948 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2949 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950}
2951
Linus Torvalds57302e02012-12-04 08:25:11 -08002952/*
2953 * This allows us to do IO even on the odd last sectors
Akinobu Mita59d43912014-10-09 15:26:53 -07002954 * of a device, even if the block size is some multiple
Linus Torvalds57302e02012-12-04 08:25:11 -08002955 * of the physical sector size.
2956 *
2957 * We'll just truncate the bio to the size of the device,
2958 * and clear the end of the buffer head manually.
2959 *
2960 * Truly out-of-range accesses will turn into actual IO
2961 * errors, this only handles the "we need to be able to
2962 * do IO at the final sector" case.
2963 */
Akinobu Mita4db96b72014-10-09 15:26:55 -07002964void guard_bio_eod(int rw, struct bio *bio)
Linus Torvalds57302e02012-12-04 08:25:11 -08002965{
2966 sector_t maxsector;
Akinobu Mita59d43912014-10-09 15:26:53 -07002967 struct bio_vec *bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
2968 unsigned truncated_bytes;
Linus Torvalds57302e02012-12-04 08:25:11 -08002969
2970 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
2971 if (!maxsector)
2972 return;
2973
2974 /*
2975 * If the *whole* IO is past the end of the device,
2976 * let it through, and the IO layer will turn it into
2977 * an EIO.
2978 */
Kent Overstreet4f024f32013-10-11 15:44:27 -07002979 if (unlikely(bio->bi_iter.bi_sector >= maxsector))
Linus Torvalds57302e02012-12-04 08:25:11 -08002980 return;
2981
Kent Overstreet4f024f32013-10-11 15:44:27 -07002982 maxsector -= bio->bi_iter.bi_sector;
Akinobu Mita59d43912014-10-09 15:26:53 -07002983 if (likely((bio->bi_iter.bi_size >> 9) <= maxsector))
Linus Torvalds57302e02012-12-04 08:25:11 -08002984 return;
2985
Akinobu Mita59d43912014-10-09 15:26:53 -07002986 /* Uhhuh. We've got a bio that straddles the device size! */
2987 truncated_bytes = bio->bi_iter.bi_size - (maxsector << 9);
Linus Torvalds57302e02012-12-04 08:25:11 -08002988
2989 /* Truncate the bio.. */
Akinobu Mita59d43912014-10-09 15:26:53 -07002990 bio->bi_iter.bi_size -= truncated_bytes;
2991 bvec->bv_len -= truncated_bytes;
Linus Torvalds57302e02012-12-04 08:25:11 -08002992
2993 /* ..and clear the end of the buffer for reads */
Dan Carpenter27d7c2a2012-12-05 20:01:24 +03002994 if ((rw & RW_MASK) == READ) {
Akinobu Mita59d43912014-10-09 15:26:53 -07002995 zero_user(bvec->bv_page, bvec->bv_offset + bvec->bv_len,
2996 truncated_bytes);
Linus Torvalds57302e02012-12-04 08:25:11 -08002997 }
2998}
2999
Darrick J. Wong7136851112013-04-29 15:07:25 -07003000int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003001{
3002 struct bio *bio;
3003 int ret = 0;
3004
3005 BUG_ON(!buffer_locked(bh));
3006 BUG_ON(!buffer_mapped(bh));
3007 BUG_ON(!bh->b_end_io);
Aneesh Kumar K.V8fb0e342009-05-12 16:22:37 -04003008 BUG_ON(buffer_delay(bh));
3009 BUG_ON(buffer_unwritten(bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003010
Jens Axboe48fd4f92008-08-22 10:00:36 +02003011 /*
Jens Axboe48fd4f92008-08-22 10:00:36 +02003012 * Only clear out a write error when rewriting
Linus Torvalds1da177e2005-04-16 15:20:36 -07003013 */
Jens Axboe48fd4f92008-08-22 10:00:36 +02003014 if (test_set_buffer_req(bh) && (rw & WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003015 clear_buffer_write_io_error(bh);
3016
3017 /*
3018 * from here on down, it's all bio -- do the initial mapping,
3019 * submit_bio -> generic_make_request may further map this bio around
3020 */
3021 bio = bio_alloc(GFP_NOIO, 1);
3022
Kent Overstreet4f024f32013-10-11 15:44:27 -07003023 bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003024 bio->bi_bdev = bh->b_bdev;
3025 bio->bi_io_vec[0].bv_page = bh->b_page;
3026 bio->bi_io_vec[0].bv_len = bh->b_size;
3027 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
3028
3029 bio->bi_vcnt = 1;
Kent Overstreet4f024f32013-10-11 15:44:27 -07003030 bio->bi_iter.bi_size = bh->b_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003031
3032 bio->bi_end_io = end_bio_bh_io_sync;
3033 bio->bi_private = bh;
Darrick J. Wong7136851112013-04-29 15:07:25 -07003034 bio->bi_flags |= bio_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003035
Linus Torvalds57302e02012-12-04 08:25:11 -08003036 /* Take care of bh's that straddle the end of the device */
Akinobu Mita59d43912014-10-09 15:26:53 -07003037 guard_bio_eod(rw, bio);
Linus Torvalds57302e02012-12-04 08:25:11 -08003038
Theodore Ts'o877f9622013-04-20 19:58:37 -04003039 if (buffer_meta(bh))
3040 rw |= REQ_META;
3041 if (buffer_prio(bh))
3042 rw |= REQ_PRIO;
3043
Linus Torvalds1da177e2005-04-16 15:20:36 -07003044 bio_get(bio);
3045 submit_bio(rw, bio);
3046
3047 if (bio_flagged(bio, BIO_EOPNOTSUPP))
3048 ret = -EOPNOTSUPP;
3049
3050 bio_put(bio);
3051 return ret;
3052}
Darrick J. Wong7136851112013-04-29 15:07:25 -07003053EXPORT_SYMBOL_GPL(_submit_bh);
3054
3055int submit_bh(int rw, struct buffer_head *bh)
3056{
3057 return _submit_bh(rw, bh, 0);
3058}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003059EXPORT_SYMBOL(submit_bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003060
3061/**
3062 * ll_rw_block: low-level access to block devices (DEPRECATED)
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003063 * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003064 * @nr: number of &struct buffer_heads in the array
3065 * @bhs: array of pointers to &struct buffer_head
3066 *
Jan Karaa7662232005-09-06 15:19:10 -07003067 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
3068 * requests an I/O operation on them, either a %READ or a %WRITE. The third
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003069 * %READA option is described in the documentation for generic_make_request()
3070 * which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003071 *
3072 * This function drops any buffer that it cannot get a lock on (with the
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003073 * BH_Lock state bit), any buffer that appears to be clean when doing a write
3074 * request, and any buffer that appears to be up-to-date when doing read
3075 * request. Further it marks as clean buffers that are processed for
3076 * writing (the buffer cache won't assume that they are actually clean
3077 * until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07003078 *
3079 * ll_rw_block sets b_end_io to simple completion handler that marks
Masanari Iidae2278672014-02-18 22:54:36 +09003080 * the buffer up-to-date (if appropriate), unlocks the buffer and wakes
Linus Torvalds1da177e2005-04-16 15:20:36 -07003081 * any waiters.
3082 *
3083 * All of the buffers must be for the same device, and must also be a
3084 * multiple of the current approved size for the device.
3085 */
3086void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
3087{
3088 int i;
3089
3090 for (i = 0; i < nr; i++) {
3091 struct buffer_head *bh = bhs[i];
3092
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003093 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003094 continue;
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003095 if (rw == WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003096 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003097 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003098 get_bh(bh);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003099 submit_bh(WRITE, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003100 continue;
3101 }
3102 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003103 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003104 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003105 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003106 submit_bh(rw, bh);
3107 continue;
3108 }
3109 }
3110 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003111 }
3112}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003113EXPORT_SYMBOL(ll_rw_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003114
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003115void write_dirty_buffer(struct buffer_head *bh, int rw)
3116{
3117 lock_buffer(bh);
3118 if (!test_clear_buffer_dirty(bh)) {
3119 unlock_buffer(bh);
3120 return;
3121 }
3122 bh->b_end_io = end_buffer_write_sync;
3123 get_bh(bh);
3124 submit_bh(rw, bh);
3125}
3126EXPORT_SYMBOL(write_dirty_buffer);
3127
Linus Torvalds1da177e2005-04-16 15:20:36 -07003128/*
3129 * For a data-integrity writeout, we need to wait upon any in-progress I/O
3130 * and then start new I/O and then wait upon it. The caller must have a ref on
3131 * the buffer_head.
3132 */
Christoph Hellwig87e99512010-08-11 17:05:45 +02003133int __sync_dirty_buffer(struct buffer_head *bh, int rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003134{
3135 int ret = 0;
3136
3137 WARN_ON(atomic_read(&bh->b_count) < 1);
3138 lock_buffer(bh);
3139 if (test_clear_buffer_dirty(bh)) {
3140 get_bh(bh);
3141 bh->b_end_io = end_buffer_write_sync;
Christoph Hellwig87e99512010-08-11 17:05:45 +02003142 ret = submit_bh(rw, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003143 wait_on_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003144 if (!ret && !buffer_uptodate(bh))
3145 ret = -EIO;
3146 } else {
3147 unlock_buffer(bh);
3148 }
3149 return ret;
3150}
Christoph Hellwig87e99512010-08-11 17:05:45 +02003151EXPORT_SYMBOL(__sync_dirty_buffer);
3152
3153int sync_dirty_buffer(struct buffer_head *bh)
3154{
3155 return __sync_dirty_buffer(bh, WRITE_SYNC);
3156}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003157EXPORT_SYMBOL(sync_dirty_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003158
3159/*
3160 * try_to_free_buffers() checks if all the buffers on this particular page
3161 * are unused, and releases them if so.
3162 *
3163 * Exclusion against try_to_free_buffers may be obtained by either
3164 * locking the page or by holding its mapping's private_lock.
3165 *
3166 * If the page is dirty but all the buffers are clean then we need to
3167 * be sure to mark the page clean as well. This is because the page
3168 * may be against a block device, and a later reattachment of buffers
3169 * to a dirty page will set *all* buffers dirty. Which would corrupt
3170 * filesystem data on the same device.
3171 *
3172 * The same applies to regular filesystem pages: if all the buffers are
3173 * clean then we set the page clean and proceed. To do that, we require
3174 * total exclusion from __set_page_dirty_buffers(). That is obtained with
3175 * private_lock.
3176 *
3177 * try_to_free_buffers() is non-blocking.
3178 */
3179static inline int buffer_busy(struct buffer_head *bh)
3180{
3181 return atomic_read(&bh->b_count) |
3182 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3183}
3184
3185static int
3186drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3187{
3188 struct buffer_head *head = page_buffers(page);
3189 struct buffer_head *bh;
3190
3191 bh = head;
3192 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07003193 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003194 set_bit(AS_EIO, &page->mapping->flags);
3195 if (buffer_busy(bh))
3196 goto failed;
3197 bh = bh->b_this_page;
3198 } while (bh != head);
3199
3200 do {
3201 struct buffer_head *next = bh->b_this_page;
3202
Jan Kara535ee2f2008-02-08 04:21:59 -08003203 if (bh->b_assoc_map)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003204 __remove_assoc_queue(bh);
3205 bh = next;
3206 } while (bh != head);
3207 *buffers_to_free = head;
3208 __clear_page_buffers(page);
3209 return 1;
3210failed:
3211 return 0;
3212}
3213
3214int try_to_free_buffers(struct page *page)
3215{
3216 struct address_space * const mapping = page->mapping;
3217 struct buffer_head *buffers_to_free = NULL;
3218 int ret = 0;
3219
3220 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003221 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003222 return 0;
3223
3224 if (mapping == NULL) { /* can this still happen? */
3225 ret = drop_buffers(page, &buffers_to_free);
3226 goto out;
3227 }
3228
3229 spin_lock(&mapping->private_lock);
3230 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003231
3232 /*
3233 * If the filesystem writes its buffers by hand (eg ext3)
3234 * then we can have clean buffers against a dirty page. We
3235 * clean the page here; otherwise the VM will never notice
3236 * that the filesystem did any IO at all.
3237 *
3238 * Also, during truncate, discard_buffer will have marked all
3239 * the page's buffers clean. We discover that here and clean
3240 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11003241 *
3242 * private_lock must be held over this entire operation in order
3243 * to synchronise against __set_page_dirty_buffers and prevent the
3244 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003245 */
Konstantin Khlebnikovb9ea2512015-04-14 15:45:27 -07003246 if (ret && TestClearPageDirty(page))
3247 account_page_cleaned(page, mapping);
Nick Piggin87df7242007-01-30 14:36:27 +11003248 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003249out:
3250 if (buffers_to_free) {
3251 struct buffer_head *bh = buffers_to_free;
3252
3253 do {
3254 struct buffer_head *next = bh->b_this_page;
3255 free_buffer_head(bh);
3256 bh = next;
3257 } while (bh != buffers_to_free);
3258 }
3259 return ret;
3260}
3261EXPORT_SYMBOL(try_to_free_buffers);
3262
Linus Torvalds1da177e2005-04-16 15:20:36 -07003263/*
3264 * There are no bdflush tunables left. But distributions are
3265 * still running obsolete flush daemons, so we terminate them here.
3266 *
3267 * Use of bdflush() is deprecated and will be removed in a future kernel.
Jens Axboe5b0830c2009-09-23 19:37:09 +02003268 * The `flush-X' kernel threads fully replace bdflush daemons and this call.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003269 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01003270SYSCALL_DEFINE2(bdflush, int, func, long, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003271{
3272 static int msg_count;
3273
3274 if (!capable(CAP_SYS_ADMIN))
3275 return -EPERM;
3276
3277 if (msg_count < 5) {
3278 msg_count++;
3279 printk(KERN_INFO
3280 "warning: process `%s' used the obsolete bdflush"
3281 " system call\n", current->comm);
3282 printk(KERN_INFO "Fix your initscripts?\n");
3283 }
3284
3285 if (func == 1)
3286 do_exit(0);
3287 return 0;
3288}
3289
3290/*
3291 * Buffer-head allocation
3292 */
Shai Fultheima0a9b042012-05-15 12:29:52 +03003293static struct kmem_cache *bh_cachep __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003294
3295/*
3296 * Once the number of bh's in the machine exceeds this level, we start
3297 * stripping them in writeback.
3298 */
Zhang Yanfei43be5942013-02-22 16:35:46 -08003299static unsigned long max_buffer_heads;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003300
3301int buffer_heads_over_limit;
3302
3303struct bh_accounting {
3304 int nr; /* Number of live bh's */
3305 int ratelimit; /* Limit cacheline bouncing */
3306};
3307
3308static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3309
3310static void recalc_bh_state(void)
3311{
3312 int i;
3313 int tot = 0;
3314
Christoph Lameteree1be862010-12-06 11:40:05 -06003315 if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003316 return;
Christoph Lameterc7b92512010-12-06 11:16:28 -06003317 __this_cpu_write(bh_accounting.ratelimit, 0);
Eric Dumazet8a143422006-03-24 03:18:10 -08003318 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003319 tot += per_cpu(bh_accounting, i).nr;
3320 buffer_heads_over_limit = (tot > max_buffer_heads);
3321}
Christoph Lameterc7b92512010-12-06 11:16:28 -06003322
Al Virodd0fc662005-10-07 07:46:04 +01003323struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003324{
Richard Kennedy019b4d12010-03-10 15:20:33 -08003325 struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003326 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07003327 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003328 preempt_disable();
3329 __this_cpu_inc(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003330 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003331 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003332 }
3333 return ret;
3334}
3335EXPORT_SYMBOL(alloc_buffer_head);
3336
3337void free_buffer_head(struct buffer_head *bh)
3338{
3339 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3340 kmem_cache_free(bh_cachep, bh);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003341 preempt_disable();
3342 __this_cpu_dec(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003343 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003344 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003345}
3346EXPORT_SYMBOL(free_buffer_head);
3347
Linus Torvalds1da177e2005-04-16 15:20:36 -07003348static void buffer_exit_cpu(int cpu)
3349{
3350 int i;
3351 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3352
3353 for (i = 0; i < BH_LRU_SIZE; i++) {
3354 brelse(b->bhs[i]);
3355 b->bhs[i] = NULL;
3356 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06003357 this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
Eric Dumazet8a143422006-03-24 03:18:10 -08003358 per_cpu(bh_accounting, cpu).nr = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003359}
3360
3361static int buffer_cpu_notify(struct notifier_block *self,
3362 unsigned long action, void *hcpu)
3363{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003364 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003365 buffer_exit_cpu((unsigned long)hcpu);
3366 return NOTIFY_OK;
3367}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003368
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003369/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003370 * bh_uptodate_or_lock - Test whether the buffer is uptodate
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003371 * @bh: struct buffer_head
3372 *
3373 * Return true if the buffer is up-to-date and false,
3374 * with the buffer locked, if not.
3375 */
3376int bh_uptodate_or_lock(struct buffer_head *bh)
3377{
3378 if (!buffer_uptodate(bh)) {
3379 lock_buffer(bh);
3380 if (!buffer_uptodate(bh))
3381 return 0;
3382 unlock_buffer(bh);
3383 }
3384 return 1;
3385}
3386EXPORT_SYMBOL(bh_uptodate_or_lock);
3387
3388/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003389 * bh_submit_read - Submit a locked buffer for reading
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003390 * @bh: struct buffer_head
3391 *
3392 * Returns zero on success and -EIO on error.
3393 */
3394int bh_submit_read(struct buffer_head *bh)
3395{
3396 BUG_ON(!buffer_locked(bh));
3397
3398 if (buffer_uptodate(bh)) {
3399 unlock_buffer(bh);
3400 return 0;
3401 }
3402
3403 get_bh(bh);
3404 bh->b_end_io = end_buffer_read_sync;
3405 submit_bh(READ, bh);
3406 wait_on_buffer(bh);
3407 if (buffer_uptodate(bh))
3408 return 0;
3409 return -EIO;
3410}
3411EXPORT_SYMBOL(bh_submit_read);
3412
Linus Torvalds1da177e2005-04-16 15:20:36 -07003413void __init buffer_init(void)
3414{
Zhang Yanfei43be5942013-02-22 16:35:46 -08003415 unsigned long nrpages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003416
Christoph Lameterb98938c2008-02-04 22:28:36 -08003417 bh_cachep = kmem_cache_create("buffer_head",
3418 sizeof(struct buffer_head), 0,
3419 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3420 SLAB_MEM_SPREAD),
Richard Kennedy019b4d12010-03-10 15:20:33 -08003421 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003422
3423 /*
3424 * Limit the bh occupancy to 10% of ZONE_NORMAL
3425 */
3426 nrpages = (nr_free_buffer_pages() * 10) / 100;
3427 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3428 hotcpu_notifier(buffer_cpu_notify, 0);
3429}