blob: 27265a8b43c1661f85d02b6fb931e8311ea7fe02 [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
Jens Axboe7eaceac2011-03-10 08:52:07 +010064static int sleep_on_buffer(void *word)
Linus Torvalds1da177e2005-04-16 15:20:36 -070065{
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 io_schedule();
67 return 0;
68}
69
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080070void __lock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071{
Jens Axboe7eaceac2011-03-10 08:52:07 +010072 wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer,
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 TASK_UNINTERRUPTIBLE);
74}
75EXPORT_SYMBOL(__lock_buffer);
76
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080077void unlock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070078{
Nick Piggin51b07fc2008-10-18 20:27:00 -070079 clear_bit_unlock(BH_Lock, &bh->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 smp_mb__after_clear_bit();
81 wake_up_bit(&bh->b_state, BH_Lock);
82}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070083EXPORT_SYMBOL(unlock_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
85/*
Mel Gormanb4597222013-07-03 15:02:05 -070086 * Returns if the page has dirty or writeback buffers. If all the buffers
87 * are unlocked and clean then the PageDirty information is stale. If
88 * any of the pages are locked, it is assumed they are locked for IO.
89 */
90void buffer_check_dirty_writeback(struct page *page,
91 bool *dirty, bool *writeback)
92{
93 struct buffer_head *head, *bh;
94 *dirty = false;
95 *writeback = false;
96
97 BUG_ON(!PageLocked(page));
98
99 if (!page_has_buffers(page))
100 return;
101
102 if (PageWriteback(page))
103 *writeback = true;
104
105 head = page_buffers(page);
106 bh = head;
107 do {
108 if (buffer_locked(bh))
109 *writeback = true;
110
111 if (buffer_dirty(bh))
112 *dirty = true;
113
114 bh = bh->b_this_page;
115 } while (bh != head);
116}
117EXPORT_SYMBOL(buffer_check_dirty_writeback);
118
119/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 * Block until a buffer comes unlocked. This doesn't stop it
121 * from becoming locked again - you have to lock it yourself
122 * if you want to preserve its state.
123 */
124void __wait_on_buffer(struct buffer_head * bh)
125{
Jens Axboe7eaceac2011-03-10 08:52:07 +0100126 wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700128EXPORT_SYMBOL(__wait_on_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
130static void
131__clear_page_buffers(struct page *page)
132{
133 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700134 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135 page_cache_release(page);
136}
137
Keith Mannthey08bafc02008-11-25 10:24:35 +0100138
139static int quiet_error(struct buffer_head *bh)
140{
141 if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
142 return 0;
143 return 1;
144}
145
146
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147static void buffer_io_error(struct buffer_head *bh)
148{
149 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
151 bdevname(bh->b_bdev, b),
152 (unsigned long long)bh->b_blocknr);
153}
154
155/*
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700156 * End-of-IO handler helper function which does not touch the bh after
157 * unlocking it.
158 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
159 * a race there is benign: unlock_buffer() only use the bh's address for
160 * hashing after unlocking the buffer, so it doesn't actually touch the bh
161 * itself.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 */
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700163static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164{
165 if (uptodate) {
166 set_buffer_uptodate(bh);
167 } else {
168 /* This happens, due to failed READA attempts. */
169 clear_buffer_uptodate(bh);
170 }
171 unlock_buffer(bh);
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700172}
173
174/*
175 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
176 * unlock the buffer. This is what ll_rw_block uses too.
177 */
178void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
179{
180 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 put_bh(bh);
182}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700183EXPORT_SYMBOL(end_buffer_read_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184
185void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
186{
187 char b[BDEVNAME_SIZE];
188
189 if (uptodate) {
190 set_buffer_uptodate(bh);
191 } else {
Christoph Hellwig0edd55f2010-08-18 05:29:23 -0400192 if (!quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 buffer_io_error(bh);
194 printk(KERN_WARNING "lost page write due to "
195 "I/O error on %s\n",
196 bdevname(bh->b_bdev, b));
197 }
198 set_buffer_write_io_error(bh);
199 clear_buffer_uptodate(bh);
200 }
201 unlock_buffer(bh);
202 put_bh(bh);
203}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700204EXPORT_SYMBOL(end_buffer_write_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205
206/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 * Various filesystems appear to want __find_get_block to be non-blocking.
208 * But it's the page lock which protects the buffers. To get around this,
209 * we get exclusion from try_to_free_buffers with the blockdev mapping's
210 * private_lock.
211 *
212 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
213 * may be quite high. This code could TryLock the page, and if that
214 * succeeds, there is no need to take private_lock. (But if
215 * private_lock is contended then so is mapping->tree_lock).
216 */
217static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800218__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219{
220 struct inode *bd_inode = bdev->bd_inode;
221 struct address_space *bd_mapping = bd_inode->i_mapping;
222 struct buffer_head *ret = NULL;
223 pgoff_t index;
224 struct buffer_head *bh;
225 struct buffer_head *head;
226 struct page *page;
227 int all_mapped = 1;
228
229 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
230 page = find_get_page(bd_mapping, index);
231 if (!page)
232 goto out;
233
234 spin_lock(&bd_mapping->private_lock);
235 if (!page_has_buffers(page))
236 goto out_unlock;
237 head = page_buffers(page);
238 bh = head;
239 do {
Nikanth Karthikesan97f76d32009-04-02 16:56:46 -0700240 if (!buffer_mapped(bh))
241 all_mapped = 0;
242 else if (bh->b_blocknr == block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 ret = bh;
244 get_bh(bh);
245 goto out_unlock;
246 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 bh = bh->b_this_page;
248 } while (bh != head);
249
250 /* we might be here because some of the buffers on this page are
251 * not mapped. This is due to various races between
252 * file io on the block device and getblk. It gets dealt with
253 * elsewhere, don't buffer_error if we had some unmapped buffers
254 */
255 if (all_mapped) {
Tao Ma72a2ebd2011-10-31 17:09:00 -0700256 char b[BDEVNAME_SIZE];
257
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 printk("__find_get_block_slow() failed. "
259 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800260 (unsigned long long)block,
261 (unsigned long long)bh->b_blocknr);
262 printk("b_state=0x%08lx, b_size=%zu\n",
263 bh->b_state, bh->b_size);
Tao Ma72a2ebd2011-10-31 17:09:00 -0700264 printk("device %s blocksize: %d\n", bdevname(bdev, b),
265 1 << bd_inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 }
267out_unlock:
268 spin_unlock(&bd_mapping->private_lock);
269 page_cache_release(page);
270out:
271 return ret;
272}
273
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274/*
Jens Axboe5b0830c2009-09-23 19:37:09 +0200275 * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 */
277static void free_more_memory(void)
278{
Mel Gorman19770b32008-04-28 02:12:18 -0700279 struct zone *zone;
Mel Gorman0e884602008-04-28 02:12:14 -0700280 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -0600282 wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 yield();
284
Mel Gorman0e884602008-04-28 02:12:14 -0700285 for_each_online_node(nid) {
Mel Gorman19770b32008-04-28 02:12:18 -0700286 (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
287 gfp_zone(GFP_NOFS), NULL,
288 &zone);
289 if (zone)
Mel Gorman54a6eb52008-04-28 02:12:16 -0700290 try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700291 GFP_NOFS, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 }
293}
294
295/*
296 * I/O completion handler for block_read_full_page() - pages
297 * which come unlocked at the end of I/O.
298 */
299static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
300{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700302 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 struct buffer_head *tmp;
304 struct page *page;
305 int page_uptodate = 1;
306
307 BUG_ON(!buffer_async_read(bh));
308
309 page = bh->b_page;
310 if (uptodate) {
311 set_buffer_uptodate(bh);
312 } else {
313 clear_buffer_uptodate(bh);
Keith Mannthey08bafc02008-11-25 10:24:35 +0100314 if (!quiet_error(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 buffer_io_error(bh);
316 SetPageError(page);
317 }
318
319 /*
320 * Be _very_ careful from here on. Bad things can happen if
321 * two buffer heads end IO at almost the same time and both
322 * decide that the page is now completely done.
323 */
Nick Piggina3972202005-07-07 17:56:56 -0700324 first = page_buffers(page);
325 local_irq_save(flags);
326 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 clear_buffer_async_read(bh);
328 unlock_buffer(bh);
329 tmp = bh;
330 do {
331 if (!buffer_uptodate(tmp))
332 page_uptodate = 0;
333 if (buffer_async_read(tmp)) {
334 BUG_ON(!buffer_locked(tmp));
335 goto still_busy;
336 }
337 tmp = tmp->b_this_page;
338 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700339 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
340 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341
342 /*
343 * If none of the buffers had errors and they are all
344 * uptodate then we can set the page uptodate.
345 */
346 if (page_uptodate && !PageError(page))
347 SetPageUptodate(page);
348 unlock_page(page);
349 return;
350
351still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700352 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
353 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 return;
355}
356
357/*
358 * Completion handler for block_write_full_page() - pages which are unlocked
359 * during I/O, and which have PageWriteback cleared upon I/O completion.
360 */
Chris Mason35c80d52009-04-15 13:22:38 -0400361void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362{
363 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700365 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 struct buffer_head *tmp;
367 struct page *page;
368
369 BUG_ON(!buffer_async_write(bh));
370
371 page = bh->b_page;
372 if (uptodate) {
373 set_buffer_uptodate(bh);
374 } else {
Keith Mannthey08bafc02008-11-25 10:24:35 +0100375 if (!quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 buffer_io_error(bh);
377 printk(KERN_WARNING "lost page write due to "
378 "I/O error on %s\n",
379 bdevname(bh->b_bdev, b));
380 }
381 set_bit(AS_EIO, &page->mapping->flags);
Jan Kara58ff407b2006-10-17 00:10:19 -0700382 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 clear_buffer_uptodate(bh);
384 SetPageError(page);
385 }
386
Nick Piggina3972202005-07-07 17:56:56 -0700387 first = page_buffers(page);
388 local_irq_save(flags);
389 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 clear_buffer_async_write(bh);
392 unlock_buffer(bh);
393 tmp = bh->b_this_page;
394 while (tmp != bh) {
395 if (buffer_async_write(tmp)) {
396 BUG_ON(!buffer_locked(tmp));
397 goto still_busy;
398 }
399 tmp = tmp->b_this_page;
400 }
Nick Piggina3972202005-07-07 17:56:56 -0700401 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
402 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 end_page_writeback(page);
404 return;
405
406still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700407 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
408 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 return;
410}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700411EXPORT_SYMBOL(end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412
413/*
414 * If a page's buffers are under async readin (end_buffer_async_read
415 * completion) then there is a possibility that another thread of
416 * control could lock one of the buffers after it has completed
417 * but while some of the other buffers have not completed. This
418 * locked buffer would confuse end_buffer_async_read() into not unlocking
419 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
420 * that this buffer is not under async I/O.
421 *
422 * The page comes unlocked when it has no locked buffer_async buffers
423 * left.
424 *
425 * PageLocked prevents anyone starting new async I/O reads any of
426 * the buffers.
427 *
428 * PageWriteback is used to prevent simultaneous writeout of the same
429 * page.
430 *
431 * PageLocked prevents anyone from starting writeback of a page which is
432 * under read I/O (PageWriteback is only ever set against a locked page).
433 */
434static void mark_buffer_async_read(struct buffer_head *bh)
435{
436 bh->b_end_io = end_buffer_async_read;
437 set_buffer_async_read(bh);
438}
439
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700440static void mark_buffer_async_write_endio(struct buffer_head *bh,
441 bh_end_io_t *handler)
Chris Mason35c80d52009-04-15 13:22:38 -0400442{
443 bh->b_end_io = handler;
444 set_buffer_async_write(bh);
445}
446
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447void mark_buffer_async_write(struct buffer_head *bh)
448{
Chris Mason35c80d52009-04-15 13:22:38 -0400449 mark_buffer_async_write_endio(bh, end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450}
451EXPORT_SYMBOL(mark_buffer_async_write);
452
453
454/*
455 * fs/buffer.c contains helper functions for buffer-backed address space's
456 * fsync functions. A common requirement for buffer-based filesystems is
457 * that certain data from the backing blockdev needs to be written out for
458 * a successful fsync(). For example, ext2 indirect blocks need to be
459 * written back and waited upon before fsync() returns.
460 *
461 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
462 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
463 * management of a list of dependent buffers at ->i_mapping->private_list.
464 *
465 * Locking is a little subtle: try_to_free_buffers() will remove buffers
466 * from their controlling inode's queue when they are being freed. But
467 * try_to_free_buffers() will be operating against the *blockdev* mapping
468 * at the time, not against the S_ISREG file which depends on those buffers.
469 * So the locking for private_list is via the private_lock in the address_space
470 * which backs the buffers. Which is different from the address_space
471 * against which the buffers are listed. So for a particular address_space,
472 * mapping->private_lock does *not* protect mapping->private_list! In fact,
473 * mapping->private_list will always be protected by the backing blockdev's
474 * ->private_lock.
475 *
476 * Which introduces a requirement: all buffers on an address_space's
477 * ->private_list must be from the same address_space: the blockdev's.
478 *
479 * address_spaces which do not place buffers at ->private_list via these
480 * utility functions are free to use private_lock and private_list for
481 * whatever they want. The only requirement is that list_empty(private_list)
482 * be true at clear_inode() time.
483 *
484 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
485 * filesystems should do that. invalidate_inode_buffers() should just go
486 * BUG_ON(!list_empty).
487 *
488 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
489 * take an address_space, not an inode. And it should be called
490 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
491 * queued up.
492 *
493 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
494 * list if it is already on a list. Because if the buffer is on a list,
495 * it *must* already be on the right one. If not, the filesystem is being
496 * silly. This will save a ton of locking. But first we have to ensure
497 * that buffers are taken *off* the old inode's list when they are freed
498 * (presumably in truncate). That requires careful auditing of all
499 * filesystems (do it inside bforget()). It could also be done by bringing
500 * b_inode back.
501 */
502
503/*
504 * The buffer's backing address_space's private_lock must be held
505 */
Thomas Petazzonidbacefc2008-07-29 22:33:47 -0700506static void __remove_assoc_queue(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507{
508 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff407b2006-10-17 00:10:19 -0700509 WARN_ON(!bh->b_assoc_map);
510 if (buffer_write_io_error(bh))
511 set_bit(AS_EIO, &bh->b_assoc_map->flags);
512 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513}
514
515int inode_has_buffers(struct inode *inode)
516{
517 return !list_empty(&inode->i_data.private_list);
518}
519
520/*
521 * osync is designed to support O_SYNC io. It waits synchronously for
522 * all already-submitted IO to complete, but does not queue any new
523 * writes to the disk.
524 *
525 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
526 * you dirty the buffers, and then use osync_inode_buffers to wait for
527 * completion. Any other dirty buffers which are not yet queued for
528 * write will not be flushed to disk by the osync.
529 */
530static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
531{
532 struct buffer_head *bh;
533 struct list_head *p;
534 int err = 0;
535
536 spin_lock(lock);
537repeat:
538 list_for_each_prev(p, list) {
539 bh = BH_ENTRY(p);
540 if (buffer_locked(bh)) {
541 get_bh(bh);
542 spin_unlock(lock);
543 wait_on_buffer(bh);
544 if (!buffer_uptodate(bh))
545 err = -EIO;
546 brelse(bh);
547 spin_lock(lock);
548 goto repeat;
549 }
550 }
551 spin_unlock(lock);
552 return err;
553}
554
Al Viro01a05b32010-03-23 06:06:58 -0400555static void do_thaw_one(struct super_block *sb, void *unused)
556{
557 char b[BDEVNAME_SIZE];
558 while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
559 printk(KERN_WARNING "Emergency Thaw on %s\n",
560 bdevname(sb->s_bdev, b));
561}
562
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700563static void do_thaw_all(struct work_struct *work)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700564{
Al Viro01a05b32010-03-23 06:06:58 -0400565 iterate_supers(do_thaw_one, NULL);
Jens Axboe053c5252009-04-08 13:44:08 +0200566 kfree(work);
Eric Sandeenc2d75432009-03-31 15:23:46 -0700567 printk(KERN_WARNING "Emergency Thaw complete\n");
568}
569
570/**
571 * emergency_thaw_all -- forcibly thaw every frozen filesystem
572 *
573 * Used for emergency unfreeze of all filesystems via SysRq
574 */
575void emergency_thaw_all(void)
576{
Jens Axboe053c5252009-04-08 13:44:08 +0200577 struct work_struct *work;
578
579 work = kmalloc(sizeof(*work), GFP_ATOMIC);
580 if (work) {
581 INIT_WORK(work, do_thaw_all);
582 schedule_work(work);
583 }
Eric Sandeenc2d75432009-03-31 15:23:46 -0700584}
585
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800587 * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700588 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589 *
590 * Starts I/O against the buffers at mapping->private_list, and waits upon
591 * that I/O.
592 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700593 * Basically, this is a convenience function for fsync().
594 * @mapping is a file or directory which needs those buffers to be written for
595 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 */
597int sync_mapping_buffers(struct address_space *mapping)
598{
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800599 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600
601 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
602 return 0;
603
604 return fsync_buffers_list(&buffer_mapping->private_lock,
605 &mapping->private_list);
606}
607EXPORT_SYMBOL(sync_mapping_buffers);
608
609/*
610 * Called when we've recently written block `bblock', and it is known that
611 * `bblock' was for a buffer_boundary() buffer. This means that the block at
612 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
613 * dirty, schedule it for IO. So that indirects merge nicely with their data.
614 */
615void write_boundary_block(struct block_device *bdev,
616 sector_t bblock, unsigned blocksize)
617{
618 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
619 if (bh) {
620 if (buffer_dirty(bh))
621 ll_rw_block(WRITE, 1, &bh);
622 put_bh(bh);
623 }
624}
625
626void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
627{
628 struct address_space *mapping = inode->i_mapping;
629 struct address_space *buffer_mapping = bh->b_page->mapping;
630
631 mark_buffer_dirty(bh);
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800632 if (!mapping->private_data) {
633 mapping->private_data = buffer_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 } else {
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800635 BUG_ON(mapping->private_data != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 }
Jan Kara535ee2f2008-02-08 04:21:59 -0800637 if (!bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638 spin_lock(&buffer_mapping->private_lock);
639 list_move_tail(&bh->b_assoc_buffers,
640 &mapping->private_list);
Jan Kara58ff407b2006-10-17 00:10:19 -0700641 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 spin_unlock(&buffer_mapping->private_lock);
643 }
644}
645EXPORT_SYMBOL(mark_buffer_dirty_inode);
646
647/*
Nick Piggin787d22142007-07-17 04:03:34 -0700648 * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
649 * dirty.
650 *
651 * If warn is true, then emit a warning if the page is not uptodate and has
652 * not been truncated.
653 */
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700654static void __set_page_dirty(struct page *page,
Nick Piggin787d22142007-07-17 04:03:34 -0700655 struct address_space *mapping, int warn)
656{
KOSAKI Motohiro227d53b32014-02-06 12:04:28 -0800657 unsigned long flags;
658
659 spin_lock_irqsave(&mapping->tree_lock, flags);
Nick Piggin787d22142007-07-17 04:03:34 -0700660 if (page->mapping) { /* Race with truncate? */
661 WARN_ON_ONCE(warn && !PageUptodate(page));
Edward Shishkine3a7cca2009-03-31 15:19:39 -0700662 account_page_dirtied(page, mapping);
Nick Piggin787d22142007-07-17 04:03:34 -0700663 radix_tree_tag_set(&mapping->page_tree,
664 page_index(page), PAGECACHE_TAG_DIRTY);
665 }
KOSAKI Motohiro227d53b32014-02-06 12:04:28 -0800666 spin_unlock_irqrestore(&mapping->tree_lock, flags);
Nick Piggin787d22142007-07-17 04:03:34 -0700667 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Nick Piggin787d22142007-07-17 04:03:34 -0700668}
669
670/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 * Add a page to the dirty page list.
672 *
673 * It is a sad fact of life that this function is called from several places
674 * deeply under spinlocking. It may not sleep.
675 *
676 * If the page has buffers, the uptodate buffers are set dirty, to preserve
677 * dirty-state coherency between the page and the buffers. It the page does
678 * not have buffers then when they are later attached they will all be set
679 * dirty.
680 *
681 * The buffers are dirtied before the page is dirtied. There's a small race
682 * window in which a writepage caller may see the page cleanness but not the
683 * buffer dirtiness. That's fine. If this code were to set the page dirty
684 * before the buffers, a concurrent writepage caller could clear the page dirty
685 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
686 * page on the dirty page list.
687 *
688 * We use private_lock to lock against try_to_free_buffers while using the
689 * page's buffer list. Also use this to protect against clean buffers being
690 * added to the page after it was set dirty.
691 *
692 * FIXME: may need to call ->reservepage here as well. That's rather up to the
693 * address_space though.
694 */
695int __set_page_dirty_buffers(struct page *page)
696{
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700697 int newly_dirty;
Nick Piggin787d22142007-07-17 04:03:34 -0700698 struct address_space *mapping = page_mapping(page);
Nick Pigginebf7a222006-10-10 04:36:54 +0200699
700 if (unlikely(!mapping))
701 return !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702
703 spin_lock(&mapping->private_lock);
704 if (page_has_buffers(page)) {
705 struct buffer_head *head = page_buffers(page);
706 struct buffer_head *bh = head;
707
708 do {
709 set_buffer_dirty(bh);
710 bh = bh->b_this_page;
711 } while (bh != head);
712 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700713 newly_dirty = !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 spin_unlock(&mapping->private_lock);
715
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700716 if (newly_dirty)
717 __set_page_dirty(page, mapping, 1);
718 return newly_dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719}
720EXPORT_SYMBOL(__set_page_dirty_buffers);
721
722/*
723 * Write out and wait upon a list of buffers.
724 *
725 * We have conflicting pressures: we want to make sure that all
726 * initially dirty buffers get waited on, but that any subsequently
727 * dirtied buffers don't. After all, we don't want fsync to last
728 * forever if somebody is actively writing to the file.
729 *
730 * Do this in two main stages: first we copy dirty buffers to a
731 * temporary inode list, queueing the writes as we go. Then we clean
732 * up, waiting for those writes to complete.
733 *
734 * During this second stage, any subsequent updates to the file may end
735 * up refiling the buffer on the original inode's dirty list again, so
736 * there is a chance we will end up with a buffer queued for write but
737 * not yet completed on that list. So, as a final cleanup we go through
738 * the osync code to catch these locked, dirty buffers without requeuing
739 * any newly dirty buffers for write.
740 */
741static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
742{
743 struct buffer_head *bh;
744 struct list_head tmp;
Jens Axboe7eaceac2011-03-10 08:52:07 +0100745 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 int err = 0, err2;
Jens Axboe4ee24912011-03-17 10:51:40 +0100747 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
749 INIT_LIST_HEAD(&tmp);
Jens Axboe4ee24912011-03-17 10:51:40 +0100750 blk_start_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751
752 spin_lock(lock);
753 while (!list_empty(list)) {
754 bh = BH_ENTRY(list->next);
Jan Kara535ee2f2008-02-08 04:21:59 -0800755 mapping = bh->b_assoc_map;
Jan Kara58ff407b2006-10-17 00:10:19 -0700756 __remove_assoc_queue(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800757 /* Avoid race with mark_buffer_dirty_inode() which does
758 * a lockless check and we rely on seeing the dirty bit */
759 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 if (buffer_dirty(bh) || buffer_locked(bh)) {
761 list_add(&bh->b_assoc_buffers, &tmp);
Jan Kara535ee2f2008-02-08 04:21:59 -0800762 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 if (buffer_dirty(bh)) {
764 get_bh(bh);
765 spin_unlock(lock);
766 /*
767 * Ensure any pending I/O completes so that
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200768 * write_dirty_buffer() actually writes the
769 * current contents - it is a noop if I/O is
770 * still in flight on potentially older
771 * contents.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772 */
Jens Axboe721a9602011-03-09 11:56:30 +0100773 write_dirty_buffer(bh, WRITE_SYNC);
Jens Axboe9cf6b722009-04-06 14:48:03 +0200774
775 /*
776 * Kick off IO for the previous mapping. Note
777 * that we will not run the very last mapping,
778 * wait_on_buffer() will do that for us
779 * through sync_buffer().
780 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 brelse(bh);
782 spin_lock(lock);
783 }
784 }
785 }
786
Jens Axboe4ee24912011-03-17 10:51:40 +0100787 spin_unlock(lock);
788 blk_finish_plug(&plug);
789 spin_lock(lock);
790
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 while (!list_empty(&tmp)) {
792 bh = BH_ENTRY(tmp.prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 get_bh(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800794 mapping = bh->b_assoc_map;
795 __remove_assoc_queue(bh);
796 /* Avoid race with mark_buffer_dirty_inode() which does
797 * a lockless check and we rely on seeing the dirty bit */
798 smp_mb();
799 if (buffer_dirty(bh)) {
800 list_add(&bh->b_assoc_buffers,
Jan Karae3892292008-03-04 14:28:33 -0800801 &mapping->private_list);
Jan Kara535ee2f2008-02-08 04:21:59 -0800802 bh->b_assoc_map = mapping;
803 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 spin_unlock(lock);
805 wait_on_buffer(bh);
806 if (!buffer_uptodate(bh))
807 err = -EIO;
808 brelse(bh);
809 spin_lock(lock);
810 }
811
812 spin_unlock(lock);
813 err2 = osync_buffers_list(lock, list);
814 if (err)
815 return err;
816 else
817 return err2;
818}
819
820/*
821 * Invalidate any and all dirty buffers on a given inode. We are
822 * probably unmounting the fs, but that doesn't mean we have already
823 * done a sync(). Just drop the buffers from the inode list.
824 *
825 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
826 * assumes that all the buffers are against the blockdev. Not true
827 * for reiserfs.
828 */
829void invalidate_inode_buffers(struct inode *inode)
830{
831 if (inode_has_buffers(inode)) {
832 struct address_space *mapping = &inode->i_data;
833 struct list_head *list = &mapping->private_list;
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800834 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835
836 spin_lock(&buffer_mapping->private_lock);
837 while (!list_empty(list))
838 __remove_assoc_queue(BH_ENTRY(list->next));
839 spin_unlock(&buffer_mapping->private_lock);
840 }
841}
Jan Kara52b19ac2008-09-23 18:24:08 +0200842EXPORT_SYMBOL(invalidate_inode_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843
844/*
845 * Remove any clean buffers from the inode's buffer list. This is called
846 * when we're trying to free the inode itself. Those buffers can pin it.
847 *
848 * Returns true if all buffers were removed.
849 */
850int remove_inode_buffers(struct inode *inode)
851{
852 int ret = 1;
853
854 if (inode_has_buffers(inode)) {
855 struct address_space *mapping = &inode->i_data;
856 struct list_head *list = &mapping->private_list;
Rafael Aquini252aa6f2012-12-11 16:02:35 -0800857 struct address_space *buffer_mapping = mapping->private_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858
859 spin_lock(&buffer_mapping->private_lock);
860 while (!list_empty(list)) {
861 struct buffer_head *bh = BH_ENTRY(list->next);
862 if (buffer_dirty(bh)) {
863 ret = 0;
864 break;
865 }
866 __remove_assoc_queue(bh);
867 }
868 spin_unlock(&buffer_mapping->private_lock);
869 }
870 return ret;
871}
872
873/*
874 * Create the appropriate buffers when given a page for data area and
875 * the size of each buffer.. Use the bh->b_this_page linked list to
876 * follow the buffers created. Return NULL if unable to create more
877 * buffers.
878 *
879 * The retry flag is used to differentiate async IO (paging, swapping)
880 * which may not fail from ordinary buffer allocations.
881 */
882struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
883 int retry)
884{
885 struct buffer_head *bh, *head;
886 long offset;
887
888try_again:
889 head = NULL;
890 offset = PAGE_SIZE;
891 while ((offset -= size) >= 0) {
892 bh = alloc_buffer_head(GFP_NOFS);
893 if (!bh)
894 goto no_grow;
895
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 bh->b_this_page = head;
897 bh->b_blocknr = -1;
898 head = bh;
899
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 bh->b_size = size;
901
902 /* Link the buffer to its page */
903 set_bh_page(bh, page, offset);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 }
905 return head;
906/*
907 * In case anything failed, we just free everything we got.
908 */
909no_grow:
910 if (head) {
911 do {
912 bh = head;
913 head = head->b_this_page;
914 free_buffer_head(bh);
915 } while (head);
916 }
917
918 /*
919 * Return failure for non-async IO requests. Async IO requests
920 * are not allowed to fail, so we have to wait until buffer heads
921 * become available. But we don't want tasks sleeping with
922 * partially complete buffers, so all were released above.
923 */
924 if (!retry)
925 return NULL;
926
927 /* We're _really_ low on memory. Now we just
928 * wait for old buffer heads to become free due to
929 * finishing IO. Since this is an async request and
930 * the reserve list is empty, we're sure there are
931 * async buffer heads in use.
932 */
933 free_more_memory();
934 goto try_again;
935}
936EXPORT_SYMBOL_GPL(alloc_page_buffers);
937
938static inline void
939link_dev_buffers(struct page *page, struct buffer_head *head)
940{
941 struct buffer_head *bh, *tail;
942
943 bh = head;
944 do {
945 tail = bh;
946 bh = bh->b_this_page;
947 } while (bh);
948 tail->b_this_page = head;
949 attach_page_buffers(page, head);
950}
951
Linus Torvaldsbbec02702012-11-29 12:31:52 -0800952static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
953{
954 sector_t retval = ~((sector_t)0);
955 loff_t sz = i_size_read(bdev->bd_inode);
956
957 if (sz) {
958 unsigned int sizebits = blksize_bits(size);
959 retval = (sz >> sizebits);
960 }
961 return retval;
962}
963
Linus Torvalds1da177e2005-04-16 15:20:36 -0700964/*
965 * Initialise the state of a blockdev page's buffers.
966 */
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200967static sector_t
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968init_page_buffers(struct page *page, struct block_device *bdev,
969 sector_t block, int size)
970{
971 struct buffer_head *head = page_buffers(page);
972 struct buffer_head *bh = head;
973 int uptodate = PageUptodate(page);
Linus Torvaldsbbec02702012-11-29 12:31:52 -0800974 sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975
976 do {
977 if (!buffer_mapped(bh)) {
978 init_buffer(bh, NULL, NULL);
979 bh->b_bdev = bdev;
980 bh->b_blocknr = block;
981 if (uptodate)
982 set_buffer_uptodate(bh);
Jeff Moyer080399a2012-05-11 16:34:10 +0200983 if (block < end_block)
984 set_buffer_mapped(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 }
986 block++;
987 bh = bh->b_this_page;
988 } while (bh != head);
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200989
990 /*
991 * Caller needs to validate requested block against end of device.
992 */
993 return end_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700994}
995
996/*
997 * Create the page-cache page that contains the requested block.
998 *
Hugh Dickins676ce6d2012-08-23 12:17:36 +0200999 * This is used purely for blockdev mappings.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000 */
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001001static int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002grow_dev_page(struct block_device *bdev, sector_t block,
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001003 pgoff_t index, int size, int sizebits)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001004{
1005 struct inode *inode = bdev->bd_inode;
1006 struct page *page;
1007 struct buffer_head *bh;
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001008 sector_t end_block;
1009 int ret = 0; /* Will call free_more_memory() */
Johannes Weiner84235de2013-10-16 13:47:00 -07001010 gfp_t gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011
Johannes Weiner84235de2013-10-16 13:47:00 -07001012 gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS;
1013 gfp_mask |= __GFP_MOVABLE;
1014 /*
1015 * XXX: __getblk_slow() can not really deal with failure and
1016 * will endlessly loop on improvised global reclaim. Prefer
1017 * looping in the allocator rather than here, at least that
1018 * code knows what it's doing.
1019 */
1020 gfp_mask |= __GFP_NOFAIL;
1021
1022 page = find_or_create_page(inode->i_mapping, index, gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 if (!page)
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001024 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025
Eric Sesterhenne827f922006-03-26 18:24:46 +02001026 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027
1028 if (page_has_buffers(page)) {
1029 bh = page_buffers(page);
1030 if (bh->b_size == size) {
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001031 end_block = init_page_buffers(page, bdev,
1032 index << sizebits, size);
1033 goto done;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 }
1035 if (!try_to_free_buffers(page))
1036 goto failed;
1037 }
1038
1039 /*
1040 * Allocate some buffers for this page
1041 */
1042 bh = alloc_page_buffers(page, size, 0);
1043 if (!bh)
1044 goto failed;
1045
1046 /*
1047 * Link the page to the buffers and initialise them. Take the
1048 * lock to be atomic wrt __find_get_block(), which does not
1049 * run under the page lock.
1050 */
1051 spin_lock(&inode->i_mapping->private_lock);
1052 link_dev_buffers(page, bh);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001053 end_block = init_page_buffers(page, bdev, index << sizebits, size);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001054 spin_unlock(&inode->i_mapping->private_lock);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001055done:
1056 ret = (block < end_block) ? 1 : -ENXIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057failed:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 unlock_page(page);
1059 page_cache_release(page);
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001060 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061}
1062
1063/*
1064 * Create buffers for the specified block device block's page. If
1065 * that page was dirty, the buffers are set dirty also.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001067static int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068grow_buffers(struct block_device *bdev, sector_t block, int size)
1069{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 pgoff_t index;
1071 int sizebits;
1072
1073 sizebits = -1;
1074 do {
1075 sizebits++;
1076 } while ((size << sizebits) < PAGE_SIZE);
1077
1078 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079
Andrew Mortone5657932006-10-11 01:21:46 -07001080 /*
1081 * Check for a block which wants to lie outside our maximum possible
1082 * pagecache index. (this comparison is done using sector_t types).
1083 */
1084 if (unlikely(index != block >> sizebits)) {
1085 char b[BDEVNAME_SIZE];
1086
1087 printk(KERN_ERR "%s: requested out-of-range block %llu for "
1088 "device %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07001089 __func__, (unsigned long long)block,
Andrew Mortone5657932006-10-11 01:21:46 -07001090 bdevname(bdev, b));
1091 return -EIO;
1092 }
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001093
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 /* Create a page with the proper size buffers.. */
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001095 return grow_dev_page(bdev, block, index, size, sizebits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096}
1097
Adrian Bunk75c96f82005-05-05 16:16:09 -07001098static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099__getblk_slow(struct block_device *bdev, sector_t block, int size)
1100{
1101 /* Size must be multiple of hard sectorsize */
Martin K. Petersene1defc42009-05-22 17:17:49 -04001102 if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 (size < 512 || size > PAGE_SIZE))) {
1104 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1105 size);
Martin K. Petersene1defc42009-05-22 17:17:49 -04001106 printk(KERN_ERR "logical block size: %d\n",
1107 bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108
1109 dump_stack();
1110 return NULL;
1111 }
1112
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001113 for (;;) {
1114 struct buffer_head *bh;
1115 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116
1117 bh = __find_get_block(bdev, block, size);
1118 if (bh)
1119 return bh;
Hugh Dickins676ce6d2012-08-23 12:17:36 +02001120
1121 ret = grow_buffers(bdev, block, size);
1122 if (ret < 0)
1123 return NULL;
1124 if (ret == 0)
1125 free_more_memory();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126 }
1127}
1128
1129/*
1130 * The relationship between dirty buffers and dirty pages:
1131 *
1132 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1133 * the page is tagged dirty in its radix tree.
1134 *
1135 * At all times, the dirtiness of the buffers represents the dirtiness of
1136 * subsections of the page. If the page has buffers, the page dirty bit is
1137 * merely a hint about the true dirty state.
1138 *
1139 * When a page is set dirty in its entirety, all its buffers are marked dirty
1140 * (if the page has buffers).
1141 *
1142 * When a buffer is marked dirty, its page is dirtied, but the page's other
1143 * buffers are not.
1144 *
1145 * Also. When blockdev buffers are explicitly read with bread(), they
1146 * individually become uptodate. But their backing page remains not
1147 * uptodate - even if all of its buffers are uptodate. A subsequent
1148 * block_read_full_page() against that page will discover all the uptodate
1149 * buffers, will set the page uptodate and will perform no I/O.
1150 */
1151
1152/**
1153 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001154 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155 *
1156 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1157 * backing page dirty, then tag the page as dirty in its address_space's radix
1158 * tree and then attach the address_space's inode to its superblock's dirty
1159 * inode list.
1160 *
1161 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
Dave Chinner250df6e2011-03-22 22:23:36 +11001162 * mapping->tree_lock and mapping->host->i_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001164void mark_buffer_dirty(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165{
Nick Piggin787d22142007-07-17 04:03:34 -07001166 WARN_ON_ONCE(!buffer_uptodate(bh));
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001167
Tejun Heo5305cb82013-01-11 13:06:36 -08001168 trace_block_dirty_buffer(bh);
1169
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001170 /*
1171 * Very *carefully* optimize the it-is-already-dirty case.
1172 *
1173 * Don't let the final "is it dirty" escape to before we
1174 * perhaps modified the buffer.
1175 */
1176 if (buffer_dirty(bh)) {
1177 smp_mb();
1178 if (buffer_dirty(bh))
1179 return;
1180 }
1181
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001182 if (!test_set_buffer_dirty(bh)) {
1183 struct page *page = bh->b_page;
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001184 if (!TestSetPageDirty(page)) {
1185 struct address_space *mapping = page_mapping(page);
1186 if (mapping)
1187 __set_page_dirty(page, mapping, 0);
1188 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001189 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001191EXPORT_SYMBOL(mark_buffer_dirty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192
1193/*
1194 * Decrement a buffer_head's reference count. If all buffers against a page
1195 * have zero reference count, are clean and unlocked, and if the page is clean
1196 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1197 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1198 * a page but it ends up not being freed, and buffers may later be reattached).
1199 */
1200void __brelse(struct buffer_head * buf)
1201{
1202 if (atomic_read(&buf->b_count)) {
1203 put_bh(buf);
1204 return;
1205 }
Arjan van de Ven5c752ad2008-07-25 19:45:40 -07001206 WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001208EXPORT_SYMBOL(__brelse);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209
1210/*
1211 * bforget() is like brelse(), except it discards any
1212 * potentially dirty data.
1213 */
1214void __bforget(struct buffer_head *bh)
1215{
1216 clear_buffer_dirty(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -08001217 if (bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 struct address_space *buffer_mapping = bh->b_page->mapping;
1219
1220 spin_lock(&buffer_mapping->private_lock);
1221 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff407b2006-10-17 00:10:19 -07001222 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001223 spin_unlock(&buffer_mapping->private_lock);
1224 }
1225 __brelse(bh);
1226}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001227EXPORT_SYMBOL(__bforget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228
1229static struct buffer_head *__bread_slow(struct buffer_head *bh)
1230{
1231 lock_buffer(bh);
1232 if (buffer_uptodate(bh)) {
1233 unlock_buffer(bh);
1234 return bh;
1235 } else {
1236 get_bh(bh);
1237 bh->b_end_io = end_buffer_read_sync;
1238 submit_bh(READ, bh);
1239 wait_on_buffer(bh);
1240 if (buffer_uptodate(bh))
1241 return bh;
1242 }
1243 brelse(bh);
1244 return NULL;
1245}
1246
1247/*
1248 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1249 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1250 * refcount elevated by one when they're in an LRU. A buffer can only appear
1251 * once in a particular CPU's LRU. A single buffer can be present in multiple
1252 * CPU's LRUs at the same time.
1253 *
1254 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1255 * sb_find_get_block().
1256 *
1257 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1258 * a local interrupt disable for that.
1259 */
1260
1261#define BH_LRU_SIZE 8
1262
1263struct bh_lru {
1264 struct buffer_head *bhs[BH_LRU_SIZE];
1265};
1266
1267static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1268
1269#ifdef CONFIG_SMP
1270#define bh_lru_lock() local_irq_disable()
1271#define bh_lru_unlock() local_irq_enable()
1272#else
1273#define bh_lru_lock() preempt_disable()
1274#define bh_lru_unlock() preempt_enable()
1275#endif
1276
1277static inline void check_irqs_on(void)
1278{
1279#ifdef irqs_disabled
1280 BUG_ON(irqs_disabled());
1281#endif
1282}
1283
1284/*
1285 * The LRU management algorithm is dopey-but-simple. Sorry.
1286 */
1287static void bh_lru_install(struct buffer_head *bh)
1288{
1289 struct buffer_head *evictee = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290
1291 check_irqs_on();
1292 bh_lru_lock();
Christoph Lameterc7b92512010-12-06 11:16:28 -06001293 if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 struct buffer_head *bhs[BH_LRU_SIZE];
1295 int in;
1296 int out = 0;
1297
1298 get_bh(bh);
1299 bhs[out++] = bh;
1300 for (in = 0; in < BH_LRU_SIZE; in++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001301 struct buffer_head *bh2 =
1302 __this_cpu_read(bh_lrus.bhs[in]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303
1304 if (bh2 == bh) {
1305 __brelse(bh2);
1306 } else {
1307 if (out >= BH_LRU_SIZE) {
1308 BUG_ON(evictee != NULL);
1309 evictee = bh2;
1310 } else {
1311 bhs[out++] = bh2;
1312 }
1313 }
1314 }
1315 while (out < BH_LRU_SIZE)
1316 bhs[out++] = NULL;
Christoph Lameterca6673b02013-12-03 17:32:53 -06001317 memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318 }
1319 bh_lru_unlock();
1320
1321 if (evictee)
1322 __brelse(evictee);
1323}
1324
1325/*
1326 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1327 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001328static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001329lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330{
1331 struct buffer_head *ret = NULL;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001332 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333
1334 check_irqs_on();
1335 bh_lru_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336 for (i = 0; i < BH_LRU_SIZE; i++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001337 struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338
1339 if (bh && bh->b_bdev == bdev &&
1340 bh->b_blocknr == block && bh->b_size == size) {
1341 if (i) {
1342 while (i) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001343 __this_cpu_write(bh_lrus.bhs[i],
1344 __this_cpu_read(bh_lrus.bhs[i - 1]));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345 i--;
1346 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06001347 __this_cpu_write(bh_lrus.bhs[0], bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348 }
1349 get_bh(bh);
1350 ret = bh;
1351 break;
1352 }
1353 }
1354 bh_lru_unlock();
1355 return ret;
1356}
1357
1358/*
1359 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1360 * it in the LRU and mark it as accessed. If it is not present then return
1361 * NULL
1362 */
1363struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001364__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365{
1366 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1367
1368 if (bh == NULL) {
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001369 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 if (bh)
1371 bh_lru_install(bh);
1372 }
1373 if (bh)
1374 touch_buffer(bh);
1375 return bh;
1376}
1377EXPORT_SYMBOL(__find_get_block);
1378
1379/*
1380 * __getblk will locate (and, if necessary, create) the buffer_head
1381 * which corresponds to the passed block_device, block and size. The
1382 * returned buffer has its reference count incremented.
1383 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1385 * attempt is failing. FIXME, perhaps?
1386 */
1387struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001388__getblk(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389{
1390 struct buffer_head *bh = __find_get_block(bdev, block, size);
1391
1392 might_sleep();
1393 if (bh == NULL)
1394 bh = __getblk_slow(bdev, block, size);
1395 return bh;
1396}
1397EXPORT_SYMBOL(__getblk);
1398
1399/*
1400 * Do async read-ahead on a buffer..
1401 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001402void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403{
1404 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001405 if (likely(bh)) {
1406 ll_rw_block(READA, 1, &bh);
1407 brelse(bh);
1408 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409}
1410EXPORT_SYMBOL(__breadahead);
1411
1412/**
1413 * __bread() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001414 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 * @block: number of block
1416 * @size: size (in bytes) to read
1417 *
1418 * Reads a specified block, and returns buffer head that contains it.
1419 * It returns NULL if the block was unreadable.
1420 */
1421struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001422__bread(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423{
1424 struct buffer_head *bh = __getblk(bdev, block, size);
1425
Andrew Mortona3e713b2005-10-30 15:03:15 -08001426 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001427 bh = __bread_slow(bh);
1428 return bh;
1429}
1430EXPORT_SYMBOL(__bread);
1431
1432/*
1433 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1434 * This doesn't race because it runs in each cpu either in irq
1435 * or with preempt disabled.
1436 */
1437static void invalidate_bh_lru(void *arg)
1438{
1439 struct bh_lru *b = &get_cpu_var(bh_lrus);
1440 int i;
1441
1442 for (i = 0; i < BH_LRU_SIZE; i++) {
1443 brelse(b->bhs[i]);
1444 b->bhs[i] = NULL;
1445 }
1446 put_cpu_var(bh_lrus);
1447}
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001448
1449static bool has_bh_in_lru(int cpu, void *dummy)
1450{
1451 struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
1452 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001454 for (i = 0; i < BH_LRU_SIZE; i++) {
1455 if (b->bhs[i])
1456 return 1;
1457 }
1458
1459 return 0;
1460}
1461
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001462void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463{
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001464 on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465}
Nick Piggin9db55792008-02-08 04:19:49 -08001466EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467
1468void set_bh_page(struct buffer_head *bh,
1469 struct page *page, unsigned long offset)
1470{
1471 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001472 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001473 if (PageHighMem(page))
1474 /*
1475 * This catches illegal uses and preserves the offset:
1476 */
1477 bh->b_data = (char *)(0 + offset);
1478 else
1479 bh->b_data = page_address(page) + offset;
1480}
1481EXPORT_SYMBOL(set_bh_page);
1482
1483/*
1484 * Called when truncating a buffer on a page completely.
1485 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001486static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487{
1488 lock_buffer(bh);
1489 clear_buffer_dirty(bh);
1490 bh->b_bdev = NULL;
1491 clear_buffer_mapped(bh);
1492 clear_buffer_req(bh);
1493 clear_buffer_new(bh);
1494 clear_buffer_delay(bh);
David Chinner33a266d2007-02-12 00:51:41 -08001495 clear_buffer_unwritten(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 unlock_buffer(bh);
1497}
1498
1499/**
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001500 * block_invalidatepage - invalidate part or all of a buffer-backed page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501 *
1502 * @page: the page which is affected
Lukas Czernerd47992f2013-05-21 23:17:23 -04001503 * @offset: start of the range to invalidate
1504 * @length: length of the range to invalidate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 *
1506 * block_invalidatepage() is called when all or part of the page has become
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001507 * invalidated by a truncate operation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001508 *
1509 * block_invalidatepage() does not have to release all buffers, but it must
1510 * ensure that no dirty buffer is left outside @offset and that no I/O
1511 * is underway against any of the blocks which are outside the truncation
1512 * point. Because the caller is about to free (and possibly reuse) those
1513 * blocks on-disk.
1514 */
Lukas Czernerd47992f2013-05-21 23:17:23 -04001515void block_invalidatepage(struct page *page, unsigned int offset,
1516 unsigned int length)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001517{
1518 struct buffer_head *head, *bh, *next;
1519 unsigned int curr_off = 0;
Lukas Czernerd47992f2013-05-21 23:17:23 -04001520 unsigned int stop = length + offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521
1522 BUG_ON(!PageLocked(page));
1523 if (!page_has_buffers(page))
1524 goto out;
1525
Lukas Czernerd47992f2013-05-21 23:17:23 -04001526 /*
1527 * Check for overflow
1528 */
1529 BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
1530
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 head = page_buffers(page);
1532 bh = head;
1533 do {
1534 unsigned int next_off = curr_off + bh->b_size;
1535 next = bh->b_this_page;
1536
1537 /*
Lukas Czernerd47992f2013-05-21 23:17:23 -04001538 * Are we still fully in range ?
1539 */
1540 if (next_off > stop)
1541 goto out;
1542
1543 /*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544 * is this block fully invalidated?
1545 */
1546 if (offset <= curr_off)
1547 discard_buffer(bh);
1548 curr_off = next_off;
1549 bh = next;
1550 } while (bh != head);
1551
1552 /*
1553 * We release buffers only if the entire page is being invalidated.
1554 * The get_block cached value has been unconditionally invalidated,
1555 * so real IO is not possible anymore.
1556 */
1557 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001558 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001560 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561}
1562EXPORT_SYMBOL(block_invalidatepage);
1563
Lukas Czernerd47992f2013-05-21 23:17:23 -04001564
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565/*
1566 * We attach and possibly dirty the buffers atomically wrt
1567 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1568 * is already excluded via the page lock.
1569 */
1570void create_empty_buffers(struct page *page,
1571 unsigned long blocksize, unsigned long b_state)
1572{
1573 struct buffer_head *bh, *head, *tail;
1574
1575 head = alloc_page_buffers(page, blocksize, 1);
1576 bh = head;
1577 do {
1578 bh->b_state |= b_state;
1579 tail = bh;
1580 bh = bh->b_this_page;
1581 } while (bh);
1582 tail->b_this_page = head;
1583
1584 spin_lock(&page->mapping->private_lock);
1585 if (PageUptodate(page) || PageDirty(page)) {
1586 bh = head;
1587 do {
1588 if (PageDirty(page))
1589 set_buffer_dirty(bh);
1590 if (PageUptodate(page))
1591 set_buffer_uptodate(bh);
1592 bh = bh->b_this_page;
1593 } while (bh != head);
1594 }
1595 attach_page_buffers(page, head);
1596 spin_unlock(&page->mapping->private_lock);
1597}
1598EXPORT_SYMBOL(create_empty_buffers);
1599
1600/*
1601 * We are taking a block for data and we don't want any output from any
1602 * buffer-cache aliases starting from return from that function and
1603 * until the moment when something will explicitly mark the buffer
1604 * dirty (hopefully that will not happen until we will free that block ;-)
1605 * We don't even need to mark it not-uptodate - nobody can expect
1606 * anything from a newly allocated buffer anyway. We used to used
1607 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1608 * don't want to mark the alias unmapped, for example - it would confuse
1609 * anyone who might pick it with bread() afterwards...
1610 *
1611 * Also.. Note that bforget() doesn't lock the buffer. So there can
1612 * be writeout I/O going on against recently-freed buffers. We don't
1613 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1614 * only if we really need to. That happens here.
1615 */
1616void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1617{
1618 struct buffer_head *old_bh;
1619
1620 might_sleep();
1621
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001622 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 if (old_bh) {
1624 clear_buffer_dirty(old_bh);
1625 wait_on_buffer(old_bh);
1626 clear_buffer_req(old_bh);
1627 __brelse(old_bh);
1628 }
1629}
1630EXPORT_SYMBOL(unmap_underlying_metadata);
1631
1632/*
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001633 * Size is a power-of-two in the range 512..PAGE_SIZE,
1634 * and the case we care about most is PAGE_SIZE.
1635 *
1636 * So this *could* possibly be written with those
1637 * constraints in mind (relevant mostly if some
1638 * architecture has a slow bit-scan instruction)
1639 */
1640static inline int block_size_bits(unsigned int blocksize)
1641{
1642 return ilog2(blocksize);
1643}
1644
1645static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state)
1646{
1647 BUG_ON(!PageLocked(page));
1648
1649 if (!page_has_buffers(page))
1650 create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state);
1651 return page_buffers(page);
1652}
1653
1654/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 * NOTE! All mapped/uptodate combinations are valid:
1656 *
1657 * Mapped Uptodate Meaning
1658 *
1659 * No No "unknown" - must do get_block()
1660 * No Yes "hole" - zero-filled
1661 * Yes No "allocated" - allocated on disk, not read in
1662 * Yes Yes "valid" - allocated and up-to-date in memory.
1663 *
1664 * "Dirty" is valid only with the last case (mapped+uptodate).
1665 */
1666
1667/*
1668 * While block_write_full_page is writing back the dirty buffers under
1669 * the page lock, whoever dirtied the buffers may decide to clean them
1670 * again at any time. We handle that by only looking at the buffer
1671 * state inside lock_buffer().
1672 *
1673 * If block_write_full_page() is called for regular writeback
1674 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1675 * locked buffer. This only can happen if someone has written the buffer
1676 * directly, with submit_bh(). At the address_space level PageWriteback
1677 * prevents this contention from occurring.
Theodore Ts'o6e34eedd2009-04-07 18:12:43 -04001678 *
1679 * If block_write_full_page() is called with wbc->sync_mode ==
Jens Axboe721a9602011-03-09 11:56:30 +01001680 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
1681 * causes the writes to be flagged as synchronous writes.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001682 */
1683static int __block_write_full_page(struct inode *inode, struct page *page,
Chris Mason35c80d52009-04-15 13:22:38 -04001684 get_block_t *get_block, struct writeback_control *wbc,
1685 bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686{
1687 int err;
1688 sector_t block;
1689 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001690 struct buffer_head *bh, *head;
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001691 unsigned int blocksize, bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 int nr_underway = 0;
Theodore Ts'o6e34eedd2009-04-07 18:12:43 -04001693 int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
Jens Axboe721a9602011-03-09 11:56:30 +01001694 WRITE_SYNC : WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001696 head = create_page_buffers(page, inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 (1 << BH_Dirty)|(1 << BH_Uptodate));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698
1699 /*
1700 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1701 * here, and the (potentially unmapped) buffers may become dirty at
1702 * any time. If a buffer becomes dirty here after we've inspected it
1703 * then we just miss that fact, and the page stays dirty.
1704 *
1705 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1706 * handle that here by just cleaning them.
1707 */
1708
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 bh = head;
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001710 blocksize = bh->b_size;
1711 bbits = block_size_bits(blocksize);
1712
1713 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1714 last_block = (i_size_read(inode) - 1) >> bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715
1716 /*
1717 * Get all the dirty buffers mapped to disk addresses and
1718 * handle any aliases from the underlying blockdev's mapping.
1719 */
1720 do {
1721 if (block > last_block) {
1722 /*
1723 * mapped buffers outside i_size will occur, because
1724 * this page can be outside i_size when there is a
1725 * truncate in progress.
1726 */
1727 /*
1728 * The buffer was zeroed by block_write_full_page()
1729 */
1730 clear_buffer_dirty(bh);
1731 set_buffer_uptodate(bh);
Alex Tomas29a814d2008-07-11 19:27:31 -04001732 } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
1733 buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001734 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735 err = get_block(inode, block, bh, 1);
1736 if (err)
1737 goto recover;
Alex Tomas29a814d2008-07-11 19:27:31 -04001738 clear_buffer_delay(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 if (buffer_new(bh)) {
1740 /* blockdev mappings never come here */
1741 clear_buffer_new(bh);
1742 unmap_underlying_metadata(bh->b_bdev,
1743 bh->b_blocknr);
1744 }
1745 }
1746 bh = bh->b_this_page;
1747 block++;
1748 } while (bh != head);
1749
1750 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001751 if (!buffer_mapped(bh))
1752 continue;
1753 /*
1754 * If it's a fully non-blocking write attempt and we cannot
1755 * lock the buffer then redirty the page. Note that this can
Jens Axboe5b0830c2009-09-23 19:37:09 +02001756 * potentially cause a busy-wait loop from writeback threads
1757 * and kswapd activity, but those code paths have their own
1758 * higher-level throttling.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 */
Wu Fengguang1b430be2010-10-26 14:21:26 -07001760 if (wbc->sync_mode != WB_SYNC_NONE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001761 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02001762 } else if (!trylock_buffer(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001763 redirty_page_for_writepage(wbc, page);
1764 continue;
1765 }
1766 if (test_clear_buffer_dirty(bh)) {
Chris Mason35c80d52009-04-15 13:22:38 -04001767 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001768 } else {
1769 unlock_buffer(bh);
1770 }
1771 } while ((bh = bh->b_this_page) != head);
1772
1773 /*
1774 * The page and its buffers are protected by PageWriteback(), so we can
1775 * drop the bh refcounts early.
1776 */
1777 BUG_ON(PageWriteback(page));
1778 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779
1780 do {
1781 struct buffer_head *next = bh->b_this_page;
1782 if (buffer_async_write(bh)) {
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001783 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 nr_underway++;
1785 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 bh = next;
1787 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001788 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789
1790 err = 0;
1791done:
1792 if (nr_underway == 0) {
1793 /*
1794 * The page was marked dirty, but the buffers were
1795 * clean. Someone wrote them back by hand with
1796 * ll_rw_block/submit_bh. A rare case.
1797 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001799
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 /*
1801 * The page and buffer_heads can be released at any time from
1802 * here on.
1803 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 }
1805 return err;
1806
1807recover:
1808 /*
1809 * ENOSPC, or some other error. We may already have added some
1810 * blocks to the file, so we need to write these out to avoid
1811 * exposing stale data.
1812 * The page is currently locked and not marked for writeback
1813 */
1814 bh = head;
1815 /* Recovery: lock and submit the mapped buffers */
1816 do {
Alex Tomas29a814d2008-07-11 19:27:31 -04001817 if (buffer_mapped(bh) && buffer_dirty(bh) &&
1818 !buffer_delay(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001819 lock_buffer(bh);
Chris Mason35c80d52009-04-15 13:22:38 -04001820 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 } else {
1822 /*
1823 * The buffer may have been set dirty during
1824 * attachment to a dirty page.
1825 */
1826 clear_buffer_dirty(bh);
1827 }
1828 } while ((bh = bh->b_this_page) != head);
1829 SetPageError(page);
1830 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001831 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001832 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833 do {
1834 struct buffer_head *next = bh->b_this_page;
1835 if (buffer_async_write(bh)) {
1836 clear_buffer_dirty(bh);
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001837 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001838 nr_underway++;
1839 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840 bh = next;
1841 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001842 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001843 goto done;
1844}
1845
Nick Pigginafddba42007-10-16 01:25:01 -07001846/*
1847 * If a page has any new buffers, zero them out here, and mark them uptodate
1848 * and dirty so they'll be written out (in order to prevent uninitialised
1849 * block data from leaking). And clear the new bit.
1850 */
1851void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1852{
1853 unsigned int block_start, block_end;
1854 struct buffer_head *head, *bh;
1855
1856 BUG_ON(!PageLocked(page));
1857 if (!page_has_buffers(page))
1858 return;
1859
1860 bh = head = page_buffers(page);
1861 block_start = 0;
1862 do {
1863 block_end = block_start + bh->b_size;
1864
1865 if (buffer_new(bh)) {
1866 if (block_end > from && block_start < to) {
1867 if (!PageUptodate(page)) {
1868 unsigned start, size;
1869
1870 start = max(from, block_start);
1871 size = min(to, block_end) - start;
1872
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001873 zero_user(page, start, size);
Nick Pigginafddba42007-10-16 01:25:01 -07001874 set_buffer_uptodate(bh);
1875 }
1876
1877 clear_buffer_new(bh);
1878 mark_buffer_dirty(bh);
1879 }
1880 }
1881
1882 block_start = block_end;
1883 bh = bh->b_this_page;
1884 } while (bh != head);
1885}
1886EXPORT_SYMBOL(page_zero_new_buffers);
1887
Christoph Hellwigebdec242010-10-06 10:47:23 +02001888int __block_write_begin(struct page *page, loff_t pos, unsigned len,
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001889 get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890{
Christoph Hellwigebdec242010-10-06 10:47:23 +02001891 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1892 unsigned to = from + len;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001893 struct inode *inode = page->mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894 unsigned block_start, block_end;
1895 sector_t block;
1896 int err = 0;
1897 unsigned blocksize, bbits;
1898 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1899
1900 BUG_ON(!PageLocked(page));
1901 BUG_ON(from > PAGE_CACHE_SIZE);
1902 BUG_ON(to > PAGE_CACHE_SIZE);
1903 BUG_ON(from > to);
1904
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001905 head = create_page_buffers(page, inode, 0);
1906 blocksize = head->b_size;
1907 bbits = block_size_bits(blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001908
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1910
1911 for(bh = head, block_start = 0; bh != head || !block_start;
1912 block++, block_start=block_end, bh = bh->b_this_page) {
1913 block_end = block_start + blocksize;
1914 if (block_end <= from || block_start >= to) {
1915 if (PageUptodate(page)) {
1916 if (!buffer_uptodate(bh))
1917 set_buffer_uptodate(bh);
1918 }
1919 continue;
1920 }
1921 if (buffer_new(bh))
1922 clear_buffer_new(bh);
1923 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001924 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925 err = get_block(inode, block, bh, 1);
1926 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001927 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 unmap_underlying_metadata(bh->b_bdev,
1930 bh->b_blocknr);
1931 if (PageUptodate(page)) {
Nick Piggin637aff42007-10-16 01:25:00 -07001932 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001933 set_buffer_uptodate(bh);
Nick Piggin637aff42007-10-16 01:25:00 -07001934 mark_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 continue;
1936 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001937 if (block_end > to || block_start < from)
1938 zero_user_segments(page,
1939 to, block_end,
1940 block_start, from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001941 continue;
1942 }
1943 }
1944 if (PageUptodate(page)) {
1945 if (!buffer_uptodate(bh))
1946 set_buffer_uptodate(bh);
1947 continue;
1948 }
1949 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08001950 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 (block_start < from || block_end > to)) {
1952 ll_rw_block(READ, 1, &bh);
1953 *wait_bh++=bh;
1954 }
1955 }
1956 /*
1957 * If we issued read requests - let them complete.
1958 */
1959 while(wait_bh > wait) {
1960 wait_on_buffer(*--wait_bh);
1961 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001962 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963 }
Jan Karaf9f07b62011-06-14 00:58:27 +02001964 if (unlikely(err))
Nick Pigginafddba42007-10-16 01:25:01 -07001965 page_zero_new_buffers(page, from, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966 return err;
1967}
Christoph Hellwigebdec242010-10-06 10:47:23 +02001968EXPORT_SYMBOL(__block_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969
1970static int __block_commit_write(struct inode *inode, struct page *page,
1971 unsigned from, unsigned to)
1972{
1973 unsigned block_start, block_end;
1974 int partial = 0;
1975 unsigned blocksize;
1976 struct buffer_head *bh, *head;
1977
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001978 bh = head = page_buffers(page);
1979 blocksize = bh->b_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001980
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001981 block_start = 0;
1982 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001983 block_end = block_start + blocksize;
1984 if (block_end <= from || block_start >= to) {
1985 if (!buffer_uptodate(bh))
1986 partial = 1;
1987 } else {
1988 set_buffer_uptodate(bh);
1989 mark_buffer_dirty(bh);
1990 }
Nick Pigginafddba42007-10-16 01:25:01 -07001991 clear_buffer_new(bh);
Linus Torvalds45bce8f2012-11-29 10:21:43 -08001992
1993 block_start = block_end;
1994 bh = bh->b_this_page;
1995 } while (bh != head);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996
1997 /*
1998 * If this is a partial write which happened to make all buffers
1999 * uptodate then we can optimize away a bogus readpage() for
2000 * the next read(). Here we 'discover' whether the page went
2001 * uptodate as a result of this (potentially partial) write.
2002 */
2003 if (!partial)
2004 SetPageUptodate(page);
2005 return 0;
2006}
2007
2008/*
Christoph Hellwig155130a2010-06-04 11:29:58 +02002009 * block_write_begin takes care of the basic task of block allocation and
2010 * bringing partial write blocks uptodate first.
2011 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002012 * The filesystem needs to handle block truncation upon failure.
Nick Pigginafddba42007-10-16 01:25:01 -07002013 */
Christoph Hellwig155130a2010-06-04 11:29:58 +02002014int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
2015 unsigned flags, struct page **pagep, get_block_t *get_block)
Nick Pigginafddba42007-10-16 01:25:01 -07002016{
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002017 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
Nick Pigginafddba42007-10-16 01:25:01 -07002018 struct page *page;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002019 int status;
Nick Pigginafddba42007-10-16 01:25:01 -07002020
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002021 page = grab_cache_page_write_begin(mapping, index, flags);
2022 if (!page)
2023 return -ENOMEM;
Nick Pigginafddba42007-10-16 01:25:01 -07002024
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002025 status = __block_write_begin(page, pos, len, get_block);
Nick Pigginafddba42007-10-16 01:25:01 -07002026 if (unlikely(status)) {
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002027 unlock_page(page);
2028 page_cache_release(page);
2029 page = NULL;
Nick Pigginafddba42007-10-16 01:25:01 -07002030 }
2031
Christoph Hellwig6e1db882010-06-04 11:29:57 +02002032 *pagep = page;
Nick Pigginafddba42007-10-16 01:25:01 -07002033 return status;
2034}
2035EXPORT_SYMBOL(block_write_begin);
2036
2037int block_write_end(struct file *file, struct address_space *mapping,
2038 loff_t pos, unsigned len, unsigned copied,
2039 struct page *page, void *fsdata)
2040{
2041 struct inode *inode = mapping->host;
2042 unsigned start;
2043
2044 start = pos & (PAGE_CACHE_SIZE - 1);
2045
2046 if (unlikely(copied < len)) {
2047 /*
2048 * The buffers that were written will now be uptodate, so we
2049 * don't have to worry about a readpage reading them and
2050 * overwriting a partial write. However if we have encountered
2051 * a short write and only partially written into a buffer, it
2052 * will not be marked uptodate, so a readpage might come in and
2053 * destroy our partial write.
2054 *
2055 * Do the simplest thing, and just treat any short write to a
2056 * non uptodate page as a zero-length write, and force the
2057 * caller to redo the whole thing.
2058 */
2059 if (!PageUptodate(page))
2060 copied = 0;
2061
2062 page_zero_new_buffers(page, start+copied, start+len);
2063 }
2064 flush_dcache_page(page);
2065
2066 /* This could be a short (even 0-length) commit */
2067 __block_commit_write(inode, page, start, start+copied);
2068
2069 return copied;
2070}
2071EXPORT_SYMBOL(block_write_end);
2072
2073int generic_write_end(struct file *file, struct address_space *mapping,
2074 loff_t pos, unsigned len, unsigned copied,
2075 struct page *page, void *fsdata)
2076{
2077 struct inode *inode = mapping->host;
Jan Karac7d206b2008-07-11 19:27:31 -04002078 int i_size_changed = 0;
Nick Pigginafddba42007-10-16 01:25:01 -07002079
2080 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2081
2082 /*
2083 * No need to use i_size_read() here, the i_size
2084 * cannot change under us because we hold i_mutex.
2085 *
2086 * But it's important to update i_size while still holding page lock:
2087 * page writeout could otherwise come in and zero beyond i_size.
2088 */
2089 if (pos+copied > inode->i_size) {
2090 i_size_write(inode, pos+copied);
Jan Karac7d206b2008-07-11 19:27:31 -04002091 i_size_changed = 1;
Nick Pigginafddba42007-10-16 01:25:01 -07002092 }
2093
2094 unlock_page(page);
2095 page_cache_release(page);
2096
Jan Karac7d206b2008-07-11 19:27:31 -04002097 /*
2098 * Don't mark the inode dirty under page lock. First, it unnecessarily
2099 * makes the holding time of page lock longer. Second, it forces lock
2100 * ordering of page lock and transaction start for journaling
2101 * filesystems.
2102 */
2103 if (i_size_changed)
2104 mark_inode_dirty(inode);
2105
Nick Pigginafddba42007-10-16 01:25:01 -07002106 return copied;
2107}
2108EXPORT_SYMBOL(generic_write_end);
2109
2110/*
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002111 * block_is_partially_uptodate checks whether buffers within a page are
2112 * uptodate or not.
2113 *
2114 * Returns true if all buffers which correspond to a file portion
2115 * we want to read are uptodate.
2116 */
2117int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
2118 unsigned long from)
2119{
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002120 unsigned block_start, block_end, blocksize;
2121 unsigned to;
2122 struct buffer_head *bh, *head;
2123 int ret = 1;
2124
2125 if (!page_has_buffers(page))
2126 return 0;
2127
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002128 head = page_buffers(page);
2129 blocksize = head->b_size;
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002130 to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
2131 to = from + to;
2132 if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2133 return 0;
2134
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002135 bh = head;
2136 block_start = 0;
2137 do {
2138 block_end = block_start + blocksize;
2139 if (block_end > from && block_start < to) {
2140 if (!buffer_uptodate(bh)) {
2141 ret = 0;
2142 break;
2143 }
2144 if (block_end >= to)
2145 break;
2146 }
2147 block_start = block_end;
2148 bh = bh->b_this_page;
2149 } while (bh != head);
2150
2151 return ret;
2152}
2153EXPORT_SYMBOL(block_is_partially_uptodate);
2154
2155/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 * Generic "read page" function for block devices that have the normal
2157 * get_block functionality. This is most of the block device filesystems.
2158 * Reads the page asynchronously --- the unlock_buffer() and
2159 * set/clear_buffer_uptodate() functions propagate buffer state into the
2160 * page struct once IO has completed.
2161 */
2162int block_read_full_page(struct page *page, get_block_t *get_block)
2163{
2164 struct inode *inode = page->mapping->host;
2165 sector_t iblock, lblock;
2166 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002167 unsigned int blocksize, bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168 int nr, i;
2169 int fully_mapped = 1;
2170
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002171 head = create_page_buffers(page, inode, 0);
2172 blocksize = head->b_size;
2173 bbits = block_size_bits(blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174
Linus Torvalds45bce8f2012-11-29 10:21:43 -08002175 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
2176 lblock = (i_size_read(inode)+blocksize-1) >> bbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177 bh = head;
2178 nr = 0;
2179 i = 0;
2180
2181 do {
2182 if (buffer_uptodate(bh))
2183 continue;
2184
2185 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002186 int err = 0;
2187
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188 fully_mapped = 0;
2189 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002190 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002191 err = get_block(inode, iblock, bh, 0);
2192 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 SetPageError(page);
2194 }
2195 if (!buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002196 zero_user(page, i * blocksize, blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002197 if (!err)
2198 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 continue;
2200 }
2201 /*
2202 * get_block() might have updated the buffer
2203 * synchronously
2204 */
2205 if (buffer_uptodate(bh))
2206 continue;
2207 }
2208 arr[nr++] = bh;
2209 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2210
2211 if (fully_mapped)
2212 SetPageMappedToDisk(page);
2213
2214 if (!nr) {
2215 /*
2216 * All buffers are uptodate - we can set the page uptodate
2217 * as well. But not if get_block() returned an error.
2218 */
2219 if (!PageError(page))
2220 SetPageUptodate(page);
2221 unlock_page(page);
2222 return 0;
2223 }
2224
2225 /* Stage two: lock the buffers */
2226 for (i = 0; i < nr; i++) {
2227 bh = arr[i];
2228 lock_buffer(bh);
2229 mark_buffer_async_read(bh);
2230 }
2231
2232 /*
2233 * Stage 3: start the IO. Check for uptodateness
2234 * inside the buffer lock in case another process reading
2235 * the underlying blockdev brought it uptodate (the sct fix).
2236 */
2237 for (i = 0; i < nr; i++) {
2238 bh = arr[i];
2239 if (buffer_uptodate(bh))
2240 end_buffer_async_read(bh, 1);
2241 else
2242 submit_bh(READ, bh);
2243 }
2244 return 0;
2245}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002246EXPORT_SYMBOL(block_read_full_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247
2248/* utility function for filesystems that need to do work on expanding
Nick Piggin89e10782007-10-16 01:25:07 -07002249 * truncates. Uses filesystem pagecache writes to allow the filesystem to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002250 * deal with the hole.
2251 */
Nick Piggin89e10782007-10-16 01:25:07 -07002252int generic_cont_expand_simple(struct inode *inode, loff_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002253{
2254 struct address_space *mapping = inode->i_mapping;
2255 struct page *page;
Nick Piggin89e10782007-10-16 01:25:07 -07002256 void *fsdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257 int err;
2258
npiggin@suse.dec08d3b02009-08-21 02:35:06 +10002259 err = inode_newsize_ok(inode, size);
2260 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 goto out;
2262
Nick Piggin89e10782007-10-16 01:25:07 -07002263 err = pagecache_write_begin(NULL, mapping, size, 0,
2264 AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2265 &page, &fsdata);
2266 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267 goto out;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002268
Nick Piggin89e10782007-10-16 01:25:07 -07002269 err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2270 BUG_ON(err > 0);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002271
Linus Torvalds1da177e2005-04-16 15:20:36 -07002272out:
2273 return err;
2274}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002275EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002276
Adrian Bunkf1e3af72008-04-29 00:59:01 -07002277static int cont_expand_zero(struct file *file, struct address_space *mapping,
2278 loff_t pos, loff_t *bytes)
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002279{
Nick Piggin89e10782007-10-16 01:25:07 -07002280 struct inode *inode = mapping->host;
2281 unsigned blocksize = 1 << inode->i_blkbits;
2282 struct page *page;
2283 void *fsdata;
2284 pgoff_t index, curidx;
2285 loff_t curpos;
2286 unsigned zerofrom, offset, len;
2287 int err = 0;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002288
Nick Piggin89e10782007-10-16 01:25:07 -07002289 index = pos >> PAGE_CACHE_SHIFT;
2290 offset = pos & ~PAGE_CACHE_MASK;
2291
2292 while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2293 zerofrom = curpos & ~PAGE_CACHE_MASK;
2294 if (zerofrom & (blocksize-1)) {
2295 *bytes |= (blocksize-1);
2296 (*bytes)++;
2297 }
2298 len = PAGE_CACHE_SIZE - zerofrom;
2299
2300 err = pagecache_write_begin(file, mapping, curpos, len,
2301 AOP_FLAG_UNINTERRUPTIBLE,
2302 &page, &fsdata);
2303 if (err)
2304 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002305 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002306 err = pagecache_write_end(file, mapping, curpos, len, len,
2307 page, fsdata);
2308 if (err < 0)
2309 goto out;
2310 BUG_ON(err != len);
2311 err = 0;
OGAWA Hirofumi061e9742008-04-28 02:16:28 -07002312
2313 balance_dirty_pages_ratelimited(mapping);
Nick Piggin89e10782007-10-16 01:25:07 -07002314 }
2315
2316 /* page covers the boundary, find the boundary offset */
2317 if (index == curidx) {
2318 zerofrom = curpos & ~PAGE_CACHE_MASK;
2319 /* if we will expand the thing last block will be filled */
2320 if (offset <= zerofrom) {
2321 goto out;
2322 }
2323 if (zerofrom & (blocksize-1)) {
2324 *bytes |= (blocksize-1);
2325 (*bytes)++;
2326 }
2327 len = offset - zerofrom;
2328
2329 err = pagecache_write_begin(file, mapping, curpos, len,
2330 AOP_FLAG_UNINTERRUPTIBLE,
2331 &page, &fsdata);
2332 if (err)
2333 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002334 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002335 err = pagecache_write_end(file, mapping, curpos, len, len,
2336 page, fsdata);
2337 if (err < 0)
2338 goto out;
2339 BUG_ON(err != len);
2340 err = 0;
2341 }
2342out:
2343 return err;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002344}
2345
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346/*
2347 * For moronic filesystems that do not allow holes in file.
2348 * We may have to extend the file.
2349 */
Christoph Hellwig282dc172010-06-04 11:29:55 +02002350int cont_write_begin(struct file *file, struct address_space *mapping,
Nick Piggin89e10782007-10-16 01:25:07 -07002351 loff_t pos, unsigned len, unsigned flags,
2352 struct page **pagep, void **fsdata,
2353 get_block_t *get_block, loff_t *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002355 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356 unsigned blocksize = 1 << inode->i_blkbits;
Nick Piggin89e10782007-10-16 01:25:07 -07002357 unsigned zerofrom;
2358 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359
Nick Piggin89e10782007-10-16 01:25:07 -07002360 err = cont_expand_zero(file, mapping, pos, bytes);
2361 if (err)
Christoph Hellwig155130a2010-06-04 11:29:58 +02002362 return err;
Nick Piggin89e10782007-10-16 01:25:07 -07002363
2364 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2365 if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2366 *bytes |= (blocksize-1);
2367 (*bytes)++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002368 }
2369
Christoph Hellwig155130a2010-06-04 11:29:58 +02002370 return block_write_begin(mapping, pos, len, flags, pagep, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002372EXPORT_SYMBOL(cont_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374int block_commit_write(struct page *page, unsigned from, unsigned to)
2375{
2376 struct inode *inode = page->mapping->host;
2377 __block_commit_write(inode,page,from,to);
2378 return 0;
2379}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002380EXPORT_SYMBOL(block_commit_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002381
David Chinner54171692007-07-19 17:39:55 +10002382/*
2383 * block_page_mkwrite() is not allowed to change the file size as it gets
2384 * called from a page fault handler when a page is first dirtied. Hence we must
2385 * be careful to check for EOF conditions here. We set the page up correctly
2386 * for a written page which means we get ENOSPC checking when writing into
2387 * holes and correct delalloc and unwritten extent mapping on filesystems that
2388 * support these features.
2389 *
2390 * We are not allowed to take the i_mutex here so we have to play games to
2391 * protect against truncate races as the page could now be beyond EOF. Because
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002392 * truncate writes the inode size before removing pages, once we have the
David Chinner54171692007-07-19 17:39:55 +10002393 * page lock we can determine safely if the page is beyond EOF. If it is not
2394 * beyond EOF, then the page is guaranteed safe against truncation until we
2395 * unlock the page.
Jan Karaea13a862011-05-24 00:23:35 +02002396 *
Jan Kara14da9202012-06-12 16:20:37 +02002397 * Direct callers of this function should protect against filesystem freezing
2398 * using sb_start_write() - sb_end_write() functions.
David Chinner54171692007-07-19 17:39:55 +10002399 */
Jan Kara24da4fa2011-05-24 00:23:34 +02002400int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2401 get_block_t get_block)
David Chinner54171692007-07-19 17:39:55 +10002402{
Nick Pigginc2ec1752009-03-31 15:23:21 -07002403 struct page *page = vmf->page;
Al Viro496ad9a2013-01-23 17:07:38 -05002404 struct inode *inode = file_inode(vma->vm_file);
David Chinner54171692007-07-19 17:39:55 +10002405 unsigned long end;
2406 loff_t size;
Jan Kara24da4fa2011-05-24 00:23:34 +02002407 int ret;
David Chinner54171692007-07-19 17:39:55 +10002408
2409 lock_page(page);
2410 size = i_size_read(inode);
2411 if ((page->mapping != inode->i_mapping) ||
Nick Piggin18336332007-07-20 00:31:45 -07002412 (page_offset(page) > size)) {
Jan Kara24da4fa2011-05-24 00:23:34 +02002413 /* We overload EFAULT to mean page got truncated */
2414 ret = -EFAULT;
2415 goto out_unlock;
David Chinner54171692007-07-19 17:39:55 +10002416 }
2417
2418 /* page is wholly or partially inside EOF */
2419 if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2420 end = size & ~PAGE_CACHE_MASK;
2421 else
2422 end = PAGE_CACHE_SIZE;
2423
Christoph Hellwigebdec242010-10-06 10:47:23 +02002424 ret = __block_write_begin(page, 0, end, get_block);
David Chinner54171692007-07-19 17:39:55 +10002425 if (!ret)
2426 ret = block_commit_write(page, 0, end);
2427
Jan Kara24da4fa2011-05-24 00:23:34 +02002428 if (unlikely(ret < 0))
2429 goto out_unlock;
Jan Karaea13a862011-05-24 00:23:35 +02002430 set_page_dirty(page);
Darrick J. Wong1d1d1a72013-02-21 16:42:51 -08002431 wait_for_stable_page(page);
Jan Kara24da4fa2011-05-24 00:23:34 +02002432 return 0;
2433out_unlock:
2434 unlock_page(page);
David Chinner54171692007-07-19 17:39:55 +10002435 return ret;
2436}
Jan Kara24da4fa2011-05-24 00:23:34 +02002437EXPORT_SYMBOL(__block_page_mkwrite);
2438
2439int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2440 get_block_t get_block)
2441{
Jan Karaea13a862011-05-24 00:23:35 +02002442 int ret;
Al Viro496ad9a2013-01-23 17:07:38 -05002443 struct super_block *sb = file_inode(vma->vm_file)->i_sb;
Jan Kara24da4fa2011-05-24 00:23:34 +02002444
Jan Kara14da9202012-06-12 16:20:37 +02002445 sb_start_pagefault(sb);
Theodore Ts'o041bbb6d2012-09-30 23:04:56 -04002446
2447 /*
2448 * Update file times before taking page lock. We may end up failing the
2449 * fault so this update may be superfluous but who really cares...
2450 */
2451 file_update_time(vma->vm_file);
2452
Jan Karaea13a862011-05-24 00:23:35 +02002453 ret = __block_page_mkwrite(vma, vmf, get_block);
Jan Kara14da9202012-06-12 16:20:37 +02002454 sb_end_pagefault(sb);
Jan Kara24da4fa2011-05-24 00:23:34 +02002455 return block_page_mkwrite_return(ret);
2456}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002457EXPORT_SYMBOL(block_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002458
2459/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002460 * nobh_write_begin()'s prereads are special: the buffer_heads are freed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461 * immediately, while under the page lock. So it needs a special end_io
2462 * handler which does not touch the bh after unlocking it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002463 */
2464static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2465{
Dmitry Monakhov68671f32007-10-16 01:24:47 -07002466 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002467}
2468
2469/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002470 * Attach the singly-linked list of buffers created by nobh_write_begin, to
2471 * the page (converting it to circular linked list and taking care of page
2472 * dirty races).
2473 */
2474static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2475{
2476 struct buffer_head *bh;
2477
2478 BUG_ON(!PageLocked(page));
2479
2480 spin_lock(&page->mapping->private_lock);
2481 bh = head;
2482 do {
2483 if (PageDirty(page))
2484 set_buffer_dirty(bh);
2485 if (!bh->b_this_page)
2486 bh->b_this_page = head;
2487 bh = bh->b_this_page;
2488 } while (bh != head);
2489 attach_page_buffers(page, head);
2490 spin_unlock(&page->mapping->private_lock);
2491}
2492
2493/*
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002494 * On entry, the page is fully not uptodate.
2495 * On exit the page is fully uptodate in the areas outside (from,to)
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002496 * The filesystem needs to handle block truncation upon failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497 */
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002498int nobh_write_begin(struct address_space *mapping,
Nick Piggin03158cd2007-10-16 01:25:25 -07002499 loff_t pos, unsigned len, unsigned flags,
2500 struct page **pagep, void **fsdata,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002501 get_block_t *get_block)
2502{
Nick Piggin03158cd2007-10-16 01:25:25 -07002503 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002504 const unsigned blkbits = inode->i_blkbits;
2505 const unsigned blocksize = 1 << blkbits;
Nick Piggina4b06722007-10-16 01:24:48 -07002506 struct buffer_head *head, *bh;
Nick Piggin03158cd2007-10-16 01:25:25 -07002507 struct page *page;
2508 pgoff_t index;
2509 unsigned from, to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510 unsigned block_in_page;
Nick Piggina4b06722007-10-16 01:24:48 -07002511 unsigned block_start, block_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512 sector_t block_in_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002513 int nr_reads = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514 int ret = 0;
2515 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516
Nick Piggin03158cd2007-10-16 01:25:25 -07002517 index = pos >> PAGE_CACHE_SHIFT;
2518 from = pos & (PAGE_CACHE_SIZE - 1);
2519 to = from + len;
2520
Nick Piggin54566b22009-01-04 12:00:53 -08002521 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Piggin03158cd2007-10-16 01:25:25 -07002522 if (!page)
2523 return -ENOMEM;
2524 *pagep = page;
2525 *fsdata = NULL;
2526
2527 if (page_has_buffers(page)) {
Namhyung Kim309f77a2010-10-25 15:01:12 +09002528 ret = __block_write_begin(page, pos, len, get_block);
2529 if (unlikely(ret))
2530 goto out_release;
2531 return ret;
Nick Piggin03158cd2007-10-16 01:25:25 -07002532 }
Nick Piggina4b06722007-10-16 01:24:48 -07002533
Linus Torvalds1da177e2005-04-16 15:20:36 -07002534 if (PageMappedToDisk(page))
2535 return 0;
2536
Nick Piggina4b06722007-10-16 01:24:48 -07002537 /*
2538 * Allocate buffers so that we can keep track of state, and potentially
2539 * attach them to the page if an error occurs. In the common case of
2540 * no error, they will just be freed again without ever being attached
2541 * to the page (which is all OK, because we're under the page lock).
2542 *
2543 * Be careful: the buffer linked list is a NULL terminated one, rather
2544 * than the circular one we're used to.
2545 */
2546 head = alloc_page_buffers(page, blocksize, 0);
Nick Piggin03158cd2007-10-16 01:25:25 -07002547 if (!head) {
2548 ret = -ENOMEM;
2549 goto out_release;
2550 }
Nick Piggina4b06722007-10-16 01:24:48 -07002551
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002553
2554 /*
2555 * We loop across all blocks in the page, whether or not they are
2556 * part of the affected region. This is so we can discover if the
2557 * page is fully mapped-to-disk.
2558 */
Nick Piggina4b06722007-10-16 01:24:48 -07002559 for (block_start = 0, block_in_page = 0, bh = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002560 block_start < PAGE_CACHE_SIZE;
Nick Piggina4b06722007-10-16 01:24:48 -07002561 block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562 int create;
2563
Nick Piggina4b06722007-10-16 01:24:48 -07002564 block_end = block_start + blocksize;
2565 bh->b_state = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002566 create = 1;
2567 if (block_start >= to)
2568 create = 0;
2569 ret = get_block(inode, block_in_file + block_in_page,
Nick Piggina4b06722007-10-16 01:24:48 -07002570 bh, create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571 if (ret)
2572 goto failed;
Nick Piggina4b06722007-10-16 01:24:48 -07002573 if (!buffer_mapped(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574 is_mapped_to_disk = 0;
Nick Piggina4b06722007-10-16 01:24:48 -07002575 if (buffer_new(bh))
2576 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2577 if (PageUptodate(page)) {
2578 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579 continue;
Nick Piggina4b06722007-10-16 01:24:48 -07002580 }
2581 if (buffer_new(bh) || !buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002582 zero_user_segments(page, block_start, from,
2583 to, block_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002584 continue;
2585 }
Nick Piggina4b06722007-10-16 01:24:48 -07002586 if (buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002587 continue; /* reiserfs does this */
2588 if (block_start < from || block_end > to) {
Nick Piggina4b06722007-10-16 01:24:48 -07002589 lock_buffer(bh);
2590 bh->b_end_io = end_buffer_read_nobh;
2591 submit_bh(READ, bh);
2592 nr_reads++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002593 }
2594 }
2595
2596 if (nr_reads) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002597 /*
2598 * The page is locked, so these buffers are protected from
2599 * any VM or truncate activity. Hence we don't need to care
2600 * for the buffer_head refcounts.
2601 */
Nick Piggina4b06722007-10-16 01:24:48 -07002602 for (bh = head; bh; bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002603 wait_on_buffer(bh);
2604 if (!buffer_uptodate(bh))
2605 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002606 }
2607 if (ret)
2608 goto failed;
2609 }
2610
2611 if (is_mapped_to_disk)
2612 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002613
Nick Piggin03158cd2007-10-16 01:25:25 -07002614 *fsdata = head; /* to be released by nobh_write_end */
Nick Piggina4b06722007-10-16 01:24:48 -07002615
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616 return 0;
2617
2618failed:
Nick Piggin03158cd2007-10-16 01:25:25 -07002619 BUG_ON(!ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002620 /*
Nick Piggina4b06722007-10-16 01:24:48 -07002621 * Error recovery is a bit difficult. We need to zero out blocks that
2622 * were newly allocated, and dirty them to ensure they get written out.
2623 * Buffers need to be attached to the page at this point, otherwise
2624 * the handling of potential IO errors during writeout would be hard
2625 * (could try doing synchronous writeout, but what if that fails too?)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002626 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002627 attach_nobh_buffers(page, head);
2628 page_zero_new_buffers(page, from, to);
Nick Piggina4b06722007-10-16 01:24:48 -07002629
Nick Piggin03158cd2007-10-16 01:25:25 -07002630out_release:
2631 unlock_page(page);
2632 page_cache_release(page);
2633 *pagep = NULL;
Nick Piggina4b06722007-10-16 01:24:48 -07002634
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002635 return ret;
2636}
Nick Piggin03158cd2007-10-16 01:25:25 -07002637EXPORT_SYMBOL(nobh_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638
Nick Piggin03158cd2007-10-16 01:25:25 -07002639int nobh_write_end(struct file *file, struct address_space *mapping,
2640 loff_t pos, unsigned len, unsigned copied,
2641 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642{
2643 struct inode *inode = page->mapping->host;
Nick Pigginefdc3132007-10-21 06:57:41 +02002644 struct buffer_head *head = fsdata;
Nick Piggin03158cd2007-10-16 01:25:25 -07002645 struct buffer_head *bh;
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002646 BUG_ON(fsdata != NULL && page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647
Dave Kleikampd4cf1092009-02-06 14:59:26 -06002648 if (unlikely(copied < len) && head)
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002649 attach_nobh_buffers(page, head);
2650 if (page_has_buffers(page))
2651 return generic_write_end(file, mapping, pos, len,
2652 copied, page, fsdata);
Nick Piggina4b06722007-10-16 01:24:48 -07002653
Nick Piggin22c8ca72007-02-20 13:58:09 -08002654 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002655 set_page_dirty(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002656 if (pos+copied > inode->i_size) {
2657 i_size_write(inode, pos+copied);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002658 mark_inode_dirty(inode);
2659 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002660
2661 unlock_page(page);
2662 page_cache_release(page);
2663
Nick Piggin03158cd2007-10-16 01:25:25 -07002664 while (head) {
2665 bh = head;
2666 head = head->b_this_page;
2667 free_buffer_head(bh);
2668 }
2669
2670 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002671}
Nick Piggin03158cd2007-10-16 01:25:25 -07002672EXPORT_SYMBOL(nobh_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673
2674/*
2675 * nobh_writepage() - based on block_full_write_page() except
2676 * that it tries to operate without attaching bufferheads to
2677 * the page.
2678 */
2679int nobh_writepage(struct page *page, get_block_t *get_block,
2680 struct writeback_control *wbc)
2681{
2682 struct inode * const inode = page->mapping->host;
2683 loff_t i_size = i_size_read(inode);
2684 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2685 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686 int ret;
2687
2688 /* Is the page fully inside i_size? */
2689 if (page->index < end_index)
2690 goto out;
2691
2692 /* Is the page fully outside i_size? (truncate in progress) */
2693 offset = i_size & (PAGE_CACHE_SIZE-1);
2694 if (page->index >= end_index+1 || !offset) {
2695 /*
2696 * The page may have dirty, unmapped buffers. For example,
2697 * they may have been added in ext3_writepage(). Make them
2698 * freeable here, so the page does not leak.
2699 */
2700#if 0
2701 /* Not really sure about this - do we need this ? */
2702 if (page->mapping->a_ops->invalidatepage)
2703 page->mapping->a_ops->invalidatepage(page, offset);
2704#endif
2705 unlock_page(page);
2706 return 0; /* don't care */
2707 }
2708
2709 /*
2710 * The page straddles i_size. It must be zeroed out on each and every
2711 * writepage invocation because it may be mmapped. "A file is mapped
2712 * in multiples of the page size. For a file that is not a multiple of
2713 * the page size, the remaining memory is zeroed when mapped, and
2714 * writes to that region are not written out to the file."
2715 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002716 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717out:
2718 ret = mpage_writepage(page, get_block, wbc);
2719 if (ret == -EAGAIN)
Chris Mason35c80d52009-04-15 13:22:38 -04002720 ret = __block_write_full_page(inode, page, get_block, wbc,
2721 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002722 return ret;
2723}
2724EXPORT_SYMBOL(nobh_writepage);
2725
Nick Piggin03158cd2007-10-16 01:25:25 -07002726int nobh_truncate_page(struct address_space *mapping,
2727 loff_t from, get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002728{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002729 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2730 unsigned offset = from & (PAGE_CACHE_SIZE-1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002731 unsigned blocksize;
2732 sector_t iblock;
2733 unsigned length, pos;
2734 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002735 struct page *page;
Nick Piggin03158cd2007-10-16 01:25:25 -07002736 struct buffer_head map_bh;
2737 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002738
Nick Piggin03158cd2007-10-16 01:25:25 -07002739 blocksize = 1 << inode->i_blkbits;
2740 length = offset & (blocksize - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002741
Nick Piggin03158cd2007-10-16 01:25:25 -07002742 /* Block boundary? Nothing to do */
2743 if (!length)
2744 return 0;
2745
2746 length = blocksize - length;
2747 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2748
Linus Torvalds1da177e2005-04-16 15:20:36 -07002749 page = grab_cache_page(mapping, index);
Nick Piggin03158cd2007-10-16 01:25:25 -07002750 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751 if (!page)
2752 goto out;
2753
Nick Piggin03158cd2007-10-16 01:25:25 -07002754 if (page_has_buffers(page)) {
2755has_buffers:
2756 unlock_page(page);
2757 page_cache_release(page);
2758 return block_truncate_page(mapping, from, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002759 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002760
2761 /* Find the buffer that contains "offset" */
2762 pos = blocksize;
2763 while (offset >= pos) {
2764 iblock++;
2765 pos += blocksize;
2766 }
2767
Theodore Ts'o460bcf52009-05-12 07:37:56 -04002768 map_bh.b_size = blocksize;
2769 map_bh.b_state = 0;
Nick Piggin03158cd2007-10-16 01:25:25 -07002770 err = get_block(inode, iblock, &map_bh, 0);
2771 if (err)
2772 goto unlock;
2773 /* unmapped? It's a hole - nothing to do */
2774 if (!buffer_mapped(&map_bh))
2775 goto unlock;
2776
2777 /* Ok, it's mapped. Make sure it's up-to-date */
2778 if (!PageUptodate(page)) {
2779 err = mapping->a_ops->readpage(NULL, page);
2780 if (err) {
2781 page_cache_release(page);
2782 goto out;
2783 }
2784 lock_page(page);
2785 if (!PageUptodate(page)) {
2786 err = -EIO;
2787 goto unlock;
2788 }
2789 if (page_has_buffers(page))
2790 goto has_buffers;
2791 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002792 zero_user(page, offset, length);
Nick Piggin03158cd2007-10-16 01:25:25 -07002793 set_page_dirty(page);
2794 err = 0;
2795
2796unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002797 unlock_page(page);
2798 page_cache_release(page);
2799out:
Nick Piggin03158cd2007-10-16 01:25:25 -07002800 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002801}
2802EXPORT_SYMBOL(nobh_truncate_page);
2803
2804int block_truncate_page(struct address_space *mapping,
2805 loff_t from, get_block_t *get_block)
2806{
2807 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2808 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2809 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002810 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002811 unsigned length, pos;
2812 struct inode *inode = mapping->host;
2813 struct page *page;
2814 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002815 int err;
2816
2817 blocksize = 1 << inode->i_blkbits;
2818 length = offset & (blocksize - 1);
2819
2820 /* Block boundary? Nothing to do */
2821 if (!length)
2822 return 0;
2823
2824 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002825 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826
2827 page = grab_cache_page(mapping, index);
2828 err = -ENOMEM;
2829 if (!page)
2830 goto out;
2831
2832 if (!page_has_buffers(page))
2833 create_empty_buffers(page, blocksize, 0);
2834
2835 /* Find the buffer that contains "offset" */
2836 bh = page_buffers(page);
2837 pos = blocksize;
2838 while (offset >= pos) {
2839 bh = bh->b_this_page;
2840 iblock++;
2841 pos += blocksize;
2842 }
2843
2844 err = 0;
2845 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002846 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002847 err = get_block(inode, iblock, bh, 0);
2848 if (err)
2849 goto unlock;
2850 /* unmapped? It's a hole - nothing to do */
2851 if (!buffer_mapped(bh))
2852 goto unlock;
2853 }
2854
2855 /* Ok, it's mapped. Make sure it's up-to-date */
2856 if (PageUptodate(page))
2857 set_buffer_uptodate(bh);
2858
David Chinner33a266d2007-02-12 00:51:41 -08002859 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860 err = -EIO;
2861 ll_rw_block(READ, 1, &bh);
2862 wait_on_buffer(bh);
2863 /* Uhhuh. Read error. Complain and punt. */
2864 if (!buffer_uptodate(bh))
2865 goto unlock;
2866 }
2867
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002868 zero_user(page, offset, length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869 mark_buffer_dirty(bh);
2870 err = 0;
2871
2872unlock:
2873 unlock_page(page);
2874 page_cache_release(page);
2875out:
2876 return err;
2877}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002878EXPORT_SYMBOL(block_truncate_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002879
2880/*
2881 * The generic ->writepage function for buffer-backed address_spaces
Chris Mason35c80d52009-04-15 13:22:38 -04002882 * this form passes in the end_io handler used to finish the IO.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002883 */
Chris Mason35c80d52009-04-15 13:22:38 -04002884int block_write_full_page_endio(struct page *page, get_block_t *get_block,
2885 struct writeback_control *wbc, bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002886{
2887 struct inode * const inode = page->mapping->host;
2888 loff_t i_size = i_size_read(inode);
2889 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2890 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002891
2892 /* Is the page fully inside i_size? */
2893 if (page->index < end_index)
Chris Mason35c80d52009-04-15 13:22:38 -04002894 return __block_write_full_page(inode, page, get_block, wbc,
2895 handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002896
2897 /* Is the page fully outside i_size? (truncate in progress) */
2898 offset = i_size & (PAGE_CACHE_SIZE-1);
2899 if (page->index >= end_index+1 || !offset) {
2900 /*
2901 * The page may have dirty, unmapped buffers. For example,
2902 * they may have been added in ext3_writepage(). Make them
2903 * freeable here, so the page does not leak.
2904 */
Lukas Czernerd47992f2013-05-21 23:17:23 -04002905 do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002906 unlock_page(page);
2907 return 0; /* don't care */
2908 }
2909
2910 /*
2911 * The page straddles i_size. It must be zeroed out on each and every
Adam Buchbinder2a61aa42009-12-11 16:35:40 -05002912 * writepage invocation because it may be mmapped. "A file is mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002913 * in multiples of the page size. For a file that is not a multiple of
2914 * the page size, the remaining memory is zeroed when mapped, and
2915 * writes to that region are not written out to the file."
2916 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002917 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Chris Mason35c80d52009-04-15 13:22:38 -04002918 return __block_write_full_page(inode, page, get_block, wbc, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002919}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002920EXPORT_SYMBOL(block_write_full_page_endio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002921
Chris Mason35c80d52009-04-15 13:22:38 -04002922/*
2923 * The generic ->writepage function for buffer-backed address_spaces
2924 */
2925int block_write_full_page(struct page *page, get_block_t *get_block,
2926 struct writeback_control *wbc)
2927{
2928 return block_write_full_page_endio(page, get_block, wbc,
2929 end_buffer_async_write);
2930}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002931EXPORT_SYMBOL(block_write_full_page);
Chris Mason35c80d52009-04-15 13:22:38 -04002932
Linus Torvalds1da177e2005-04-16 15:20:36 -07002933sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2934 get_block_t *get_block)
2935{
2936 struct buffer_head tmp;
2937 struct inode *inode = mapping->host;
2938 tmp.b_state = 0;
2939 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002940 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002941 get_block(inode, block, &tmp, 0);
2942 return tmp.b_blocknr;
2943}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002944EXPORT_SYMBOL(generic_block_bmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002945
NeilBrown6712ecf2007-09-27 12:47:43 +02002946static void end_bio_bh_io_sync(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002947{
2948 struct buffer_head *bh = bio->bi_private;
2949
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950 if (err == -EOPNOTSUPP) {
2951 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002952 }
2953
Keith Mannthey08bafc02008-11-25 10:24:35 +01002954 if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2955 set_bit(BH_Quiet, &bh->b_state);
2956
Linus Torvalds1da177e2005-04-16 15:20:36 -07002957 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2958 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002959}
2960
Linus Torvalds57302e02012-12-04 08:25:11 -08002961/*
2962 * This allows us to do IO even on the odd last sectors
2963 * of a device, even if the bh block size is some multiple
2964 * of the physical sector size.
2965 *
2966 * We'll just truncate the bio to the size of the device,
2967 * and clear the end of the buffer head manually.
2968 *
2969 * Truly out-of-range accesses will turn into actual IO
2970 * errors, this only handles the "we need to be able to
2971 * do IO at the final sector" case.
2972 */
2973static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh)
2974{
2975 sector_t maxsector;
2976 unsigned bytes;
2977
2978 maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
2979 if (!maxsector)
2980 return;
2981
2982 /*
2983 * If the *whole* IO is past the end of the device,
2984 * let it through, and the IO layer will turn it into
2985 * an EIO.
2986 */
Kent Overstreet4f024f32013-10-11 15:44:27 -07002987 if (unlikely(bio->bi_iter.bi_sector >= maxsector))
Linus Torvalds57302e02012-12-04 08:25:11 -08002988 return;
2989
Kent Overstreet4f024f32013-10-11 15:44:27 -07002990 maxsector -= bio->bi_iter.bi_sector;
2991 bytes = bio->bi_iter.bi_size;
Linus Torvalds57302e02012-12-04 08:25:11 -08002992 if (likely((bytes >> 9) <= maxsector))
2993 return;
2994
2995 /* Uhhuh. We've got a bh that straddles the device size! */
2996 bytes = maxsector << 9;
2997
2998 /* Truncate the bio.. */
Kent Overstreet4f024f32013-10-11 15:44:27 -07002999 bio->bi_iter.bi_size = bytes;
Linus Torvalds57302e02012-12-04 08:25:11 -08003000 bio->bi_io_vec[0].bv_len = bytes;
3001
3002 /* ..and clear the end of the buffer for reads */
Dan Carpenter27d7c2a2012-12-05 20:01:24 +03003003 if ((rw & RW_MASK) == READ) {
Linus Torvalds57302e02012-12-04 08:25:11 -08003004 void *kaddr = kmap_atomic(bh->b_page);
3005 memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes);
3006 kunmap_atomic(kaddr);
Linus Torvalds6d283db2013-01-14 13:17:50 -08003007 flush_dcache_page(bh->b_page);
Linus Torvalds57302e02012-12-04 08:25:11 -08003008 }
3009}
3010
Darrick J. Wong7136851112013-04-29 15:07:25 -07003011int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003012{
3013 struct bio *bio;
3014 int ret = 0;
3015
3016 BUG_ON(!buffer_locked(bh));
3017 BUG_ON(!buffer_mapped(bh));
3018 BUG_ON(!bh->b_end_io);
Aneesh Kumar K.V8fb0e342009-05-12 16:22:37 -04003019 BUG_ON(buffer_delay(bh));
3020 BUG_ON(buffer_unwritten(bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -07003021
Jens Axboe48fd4f92008-08-22 10:00:36 +02003022 /*
Jens Axboe48fd4f92008-08-22 10:00:36 +02003023 * Only clear out a write error when rewriting
Linus Torvalds1da177e2005-04-16 15:20:36 -07003024 */
Jens Axboe48fd4f92008-08-22 10:00:36 +02003025 if (test_set_buffer_req(bh) && (rw & WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003026 clear_buffer_write_io_error(bh);
3027
3028 /*
3029 * from here on down, it's all bio -- do the initial mapping,
3030 * submit_bio -> generic_make_request may further map this bio around
3031 */
3032 bio = bio_alloc(GFP_NOIO, 1);
3033
Kent Overstreet4f024f32013-10-11 15:44:27 -07003034 bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003035 bio->bi_bdev = bh->b_bdev;
3036 bio->bi_io_vec[0].bv_page = bh->b_page;
3037 bio->bi_io_vec[0].bv_len = bh->b_size;
3038 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
3039
3040 bio->bi_vcnt = 1;
Kent Overstreet4f024f32013-10-11 15:44:27 -07003041 bio->bi_iter.bi_size = bh->b_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003042
3043 bio->bi_end_io = end_bio_bh_io_sync;
3044 bio->bi_private = bh;
Darrick J. Wong7136851112013-04-29 15:07:25 -07003045 bio->bi_flags |= bio_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003046
Linus Torvalds57302e02012-12-04 08:25:11 -08003047 /* Take care of bh's that straddle the end of the device */
3048 guard_bh_eod(rw, bio, bh);
3049
Theodore Ts'o877f9622013-04-20 19:58:37 -04003050 if (buffer_meta(bh))
3051 rw |= REQ_META;
3052 if (buffer_prio(bh))
3053 rw |= REQ_PRIO;
3054
Linus Torvalds1da177e2005-04-16 15:20:36 -07003055 bio_get(bio);
3056 submit_bio(rw, bio);
3057
3058 if (bio_flagged(bio, BIO_EOPNOTSUPP))
3059 ret = -EOPNOTSUPP;
3060
3061 bio_put(bio);
3062 return ret;
3063}
Darrick J. Wong7136851112013-04-29 15:07:25 -07003064EXPORT_SYMBOL_GPL(_submit_bh);
3065
3066int submit_bh(int rw, struct buffer_head *bh)
3067{
3068 return _submit_bh(rw, bh, 0);
3069}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003070EXPORT_SYMBOL(submit_bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003071
3072/**
3073 * ll_rw_block: low-level access to block devices (DEPRECATED)
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003074 * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003075 * @nr: number of &struct buffer_heads in the array
3076 * @bhs: array of pointers to &struct buffer_head
3077 *
Jan Karaa7662232005-09-06 15:19:10 -07003078 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
3079 * requests an I/O operation on them, either a %READ or a %WRITE. The third
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003080 * %READA option is described in the documentation for generic_make_request()
3081 * which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003082 *
3083 * This function drops any buffer that it cannot get a lock on (with the
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003084 * BH_Lock state bit), any buffer that appears to be clean when doing a write
3085 * request, and any buffer that appears to be up-to-date when doing read
3086 * request. Further it marks as clean buffers that are processed for
3087 * writing (the buffer cache won't assume that they are actually clean
3088 * until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07003089 *
3090 * ll_rw_block sets b_end_io to simple completion handler that marks
3091 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
3092 * any waiters.
3093 *
3094 * All of the buffers must be for the same device, and must also be a
3095 * multiple of the current approved size for the device.
3096 */
3097void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
3098{
3099 int i;
3100
3101 for (i = 0; i < nr; i++) {
3102 struct buffer_head *bh = bhs[i];
3103
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003104 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003105 continue;
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003106 if (rw == WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003107 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003108 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003109 get_bh(bh);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003110 submit_bh(WRITE, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003111 continue;
3112 }
3113 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003114 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003115 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003116 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003117 submit_bh(rw, bh);
3118 continue;
3119 }
3120 }
3121 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003122 }
3123}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003124EXPORT_SYMBOL(ll_rw_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003125
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02003126void write_dirty_buffer(struct buffer_head *bh, int rw)
3127{
3128 lock_buffer(bh);
3129 if (!test_clear_buffer_dirty(bh)) {
3130 unlock_buffer(bh);
3131 return;
3132 }
3133 bh->b_end_io = end_buffer_write_sync;
3134 get_bh(bh);
3135 submit_bh(rw, bh);
3136}
3137EXPORT_SYMBOL(write_dirty_buffer);
3138
Linus Torvalds1da177e2005-04-16 15:20:36 -07003139/*
3140 * For a data-integrity writeout, we need to wait upon any in-progress I/O
3141 * and then start new I/O and then wait upon it. The caller must have a ref on
3142 * the buffer_head.
3143 */
Christoph Hellwig87e99512010-08-11 17:05:45 +02003144int __sync_dirty_buffer(struct buffer_head *bh, int rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003145{
3146 int ret = 0;
3147
3148 WARN_ON(atomic_read(&bh->b_count) < 1);
3149 lock_buffer(bh);
3150 if (test_clear_buffer_dirty(bh)) {
3151 get_bh(bh);
3152 bh->b_end_io = end_buffer_write_sync;
Christoph Hellwig87e99512010-08-11 17:05:45 +02003153 ret = submit_bh(rw, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003154 wait_on_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003155 if (!ret && !buffer_uptodate(bh))
3156 ret = -EIO;
3157 } else {
3158 unlock_buffer(bh);
3159 }
3160 return ret;
3161}
Christoph Hellwig87e99512010-08-11 17:05:45 +02003162EXPORT_SYMBOL(__sync_dirty_buffer);
3163
3164int sync_dirty_buffer(struct buffer_head *bh)
3165{
3166 return __sync_dirty_buffer(bh, WRITE_SYNC);
3167}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003168EXPORT_SYMBOL(sync_dirty_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003169
3170/*
3171 * try_to_free_buffers() checks if all the buffers on this particular page
3172 * are unused, and releases them if so.
3173 *
3174 * Exclusion against try_to_free_buffers may be obtained by either
3175 * locking the page or by holding its mapping's private_lock.
3176 *
3177 * If the page is dirty but all the buffers are clean then we need to
3178 * be sure to mark the page clean as well. This is because the page
3179 * may be against a block device, and a later reattachment of buffers
3180 * to a dirty page will set *all* buffers dirty. Which would corrupt
3181 * filesystem data on the same device.
3182 *
3183 * The same applies to regular filesystem pages: if all the buffers are
3184 * clean then we set the page clean and proceed. To do that, we require
3185 * total exclusion from __set_page_dirty_buffers(). That is obtained with
3186 * private_lock.
3187 *
3188 * try_to_free_buffers() is non-blocking.
3189 */
3190static inline int buffer_busy(struct buffer_head *bh)
3191{
3192 return atomic_read(&bh->b_count) |
3193 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3194}
3195
3196static int
3197drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3198{
3199 struct buffer_head *head = page_buffers(page);
3200 struct buffer_head *bh;
3201
3202 bh = head;
3203 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07003204 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003205 set_bit(AS_EIO, &page->mapping->flags);
3206 if (buffer_busy(bh))
3207 goto failed;
3208 bh = bh->b_this_page;
3209 } while (bh != head);
3210
3211 do {
3212 struct buffer_head *next = bh->b_this_page;
3213
Jan Kara535ee2f2008-02-08 04:21:59 -08003214 if (bh->b_assoc_map)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003215 __remove_assoc_queue(bh);
3216 bh = next;
3217 } while (bh != head);
3218 *buffers_to_free = head;
3219 __clear_page_buffers(page);
3220 return 1;
3221failed:
3222 return 0;
3223}
3224
3225int try_to_free_buffers(struct page *page)
3226{
3227 struct address_space * const mapping = page->mapping;
3228 struct buffer_head *buffers_to_free = NULL;
3229 int ret = 0;
3230
3231 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003232 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003233 return 0;
3234
3235 if (mapping == NULL) { /* can this still happen? */
3236 ret = drop_buffers(page, &buffers_to_free);
3237 goto out;
3238 }
3239
3240 spin_lock(&mapping->private_lock);
3241 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003242
3243 /*
3244 * If the filesystem writes its buffers by hand (eg ext3)
3245 * then we can have clean buffers against a dirty page. We
3246 * clean the page here; otherwise the VM will never notice
3247 * that the filesystem did any IO at all.
3248 *
3249 * Also, during truncate, discard_buffer will have marked all
3250 * the page's buffers clean. We discover that here and clean
3251 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11003252 *
3253 * private_lock must be held over this entire operation in order
3254 * to synchronise against __set_page_dirty_buffers and prevent the
3255 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003256 */
3257 if (ret)
3258 cancel_dirty_page(page, PAGE_CACHE_SIZE);
Nick Piggin87df7242007-01-30 14:36:27 +11003259 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003260out:
3261 if (buffers_to_free) {
3262 struct buffer_head *bh = buffers_to_free;
3263
3264 do {
3265 struct buffer_head *next = bh->b_this_page;
3266 free_buffer_head(bh);
3267 bh = next;
3268 } while (bh != buffers_to_free);
3269 }
3270 return ret;
3271}
3272EXPORT_SYMBOL(try_to_free_buffers);
3273
Linus Torvalds1da177e2005-04-16 15:20:36 -07003274/*
3275 * There are no bdflush tunables left. But distributions are
3276 * still running obsolete flush daemons, so we terminate them here.
3277 *
3278 * Use of bdflush() is deprecated and will be removed in a future kernel.
Jens Axboe5b0830c2009-09-23 19:37:09 +02003279 * The `flush-X' kernel threads fully replace bdflush daemons and this call.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003280 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01003281SYSCALL_DEFINE2(bdflush, int, func, long, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003282{
3283 static int msg_count;
3284
3285 if (!capable(CAP_SYS_ADMIN))
3286 return -EPERM;
3287
3288 if (msg_count < 5) {
3289 msg_count++;
3290 printk(KERN_INFO
3291 "warning: process `%s' used the obsolete bdflush"
3292 " system call\n", current->comm);
3293 printk(KERN_INFO "Fix your initscripts?\n");
3294 }
3295
3296 if (func == 1)
3297 do_exit(0);
3298 return 0;
3299}
3300
3301/*
3302 * Buffer-head allocation
3303 */
Shai Fultheima0a9b042012-05-15 12:29:52 +03003304static struct kmem_cache *bh_cachep __read_mostly;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003305
3306/*
3307 * Once the number of bh's in the machine exceeds this level, we start
3308 * stripping them in writeback.
3309 */
Zhang Yanfei43be5942013-02-22 16:35:46 -08003310static unsigned long max_buffer_heads;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003311
3312int buffer_heads_over_limit;
3313
3314struct bh_accounting {
3315 int nr; /* Number of live bh's */
3316 int ratelimit; /* Limit cacheline bouncing */
3317};
3318
3319static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3320
3321static void recalc_bh_state(void)
3322{
3323 int i;
3324 int tot = 0;
3325
Christoph Lameteree1be862010-12-06 11:40:05 -06003326 if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003327 return;
Christoph Lameterc7b92512010-12-06 11:16:28 -06003328 __this_cpu_write(bh_accounting.ratelimit, 0);
Eric Dumazet8a143422006-03-24 03:18:10 -08003329 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003330 tot += per_cpu(bh_accounting, i).nr;
3331 buffer_heads_over_limit = (tot > max_buffer_heads);
3332}
Christoph Lameterc7b92512010-12-06 11:16:28 -06003333
Al Virodd0fc662005-10-07 07:46:04 +01003334struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003335{
Richard Kennedy019b4d12010-03-10 15:20:33 -08003336 struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003337 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07003338 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003339 preempt_disable();
3340 __this_cpu_inc(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003341 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003342 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003343 }
3344 return ret;
3345}
3346EXPORT_SYMBOL(alloc_buffer_head);
3347
3348void free_buffer_head(struct buffer_head *bh)
3349{
3350 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3351 kmem_cache_free(bh_cachep, bh);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003352 preempt_disable();
3353 __this_cpu_dec(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003354 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003355 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003356}
3357EXPORT_SYMBOL(free_buffer_head);
3358
Linus Torvalds1da177e2005-04-16 15:20:36 -07003359static void buffer_exit_cpu(int cpu)
3360{
3361 int i;
3362 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3363
3364 for (i = 0; i < BH_LRU_SIZE; i++) {
3365 brelse(b->bhs[i]);
3366 b->bhs[i] = NULL;
3367 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06003368 this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
Eric Dumazet8a143422006-03-24 03:18:10 -08003369 per_cpu(bh_accounting, cpu).nr = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003370}
3371
3372static int buffer_cpu_notify(struct notifier_block *self,
3373 unsigned long action, void *hcpu)
3374{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003375 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003376 buffer_exit_cpu((unsigned long)hcpu);
3377 return NOTIFY_OK;
3378}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003379
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003380/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003381 * bh_uptodate_or_lock - Test whether the buffer is uptodate
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003382 * @bh: struct buffer_head
3383 *
3384 * Return true if the buffer is up-to-date and false,
3385 * with the buffer locked, if not.
3386 */
3387int bh_uptodate_or_lock(struct buffer_head *bh)
3388{
3389 if (!buffer_uptodate(bh)) {
3390 lock_buffer(bh);
3391 if (!buffer_uptodate(bh))
3392 return 0;
3393 unlock_buffer(bh);
3394 }
3395 return 1;
3396}
3397EXPORT_SYMBOL(bh_uptodate_or_lock);
3398
3399/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003400 * bh_submit_read - Submit a locked buffer for reading
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003401 * @bh: struct buffer_head
3402 *
3403 * Returns zero on success and -EIO on error.
3404 */
3405int bh_submit_read(struct buffer_head *bh)
3406{
3407 BUG_ON(!buffer_locked(bh));
3408
3409 if (buffer_uptodate(bh)) {
3410 unlock_buffer(bh);
3411 return 0;
3412 }
3413
3414 get_bh(bh);
3415 bh->b_end_io = end_buffer_read_sync;
3416 submit_bh(READ, bh);
3417 wait_on_buffer(bh);
3418 if (buffer_uptodate(bh))
3419 return 0;
3420 return -EIO;
3421}
3422EXPORT_SYMBOL(bh_submit_read);
3423
Linus Torvalds1da177e2005-04-16 15:20:36 -07003424void __init buffer_init(void)
3425{
Zhang Yanfei43be5942013-02-22 16:35:46 -08003426 unsigned long nrpages;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003427
Christoph Lameterb98938c2008-02-04 22:28:36 -08003428 bh_cachep = kmem_cache_create("buffer_head",
3429 sizeof(struct buffer_head), 0,
3430 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3431 SLAB_MEM_SPREAD),
Richard Kennedy019b4d12010-03-10 15:20:33 -08003432 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003433
3434 /*
3435 * Limit the bh occupancy to 10% of ZONE_NORMAL
3436 */
3437 nrpages = (nr_free_buffer_pages() * 10) / 100;
3438 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3439 hotcpu_notifier(buffer_cpu_notify, 0);
3440}