blob: 351e18ea2e53a911abcab29f57325a4f31ded786 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
47#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
48
49inline void
50init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
51{
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
Jens Axboe7eaceac2011-03-10 08:52:07 +010057static int sleep_on_buffer(void *word)
Linus Torvalds1da177e2005-04-16 15:20:36 -070058{
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 io_schedule();
60 return 0;
61}
62
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080063void __lock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070064{
Jens Axboe7eaceac2011-03-10 08:52:07 +010065 wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer,
Linus Torvalds1da177e2005-04-16 15:20:36 -070066 TASK_UNINTERRUPTIBLE);
67}
68EXPORT_SYMBOL(__lock_buffer);
69
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080070void unlock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071{
Nick Piggin51b07fc2008-10-18 20:27:00 -070072 clear_bit_unlock(BH_Lock, &bh->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -070073 smp_mb__after_clear_bit();
74 wake_up_bit(&bh->b_state, BH_Lock);
75}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070076EXPORT_SYMBOL(unlock_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
78/*
79 * Block until a buffer comes unlocked. This doesn't stop it
80 * from becoming locked again - you have to lock it yourself
81 * if you want to preserve its state.
82 */
83void __wait_on_buffer(struct buffer_head * bh)
84{
Jens Axboe7eaceac2011-03-10 08:52:07 +010085 wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070087EXPORT_SYMBOL(__wait_on_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070088
89static void
90__clear_page_buffers(struct page *page)
91{
92 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070093 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070094 page_cache_release(page);
95}
96
Keith Mannthey08bafc02008-11-25 10:24:35 +010097
98static int quiet_error(struct buffer_head *bh)
99{
100 if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
101 return 0;
102 return 1;
103}
104
105
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106static void buffer_io_error(struct buffer_head *bh)
107{
108 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
110 bdevname(bh->b_bdev, b),
111 (unsigned long long)bh->b_blocknr);
112}
113
114/*
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700115 * End-of-IO handler helper function which does not touch the bh after
116 * unlocking it.
117 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
118 * a race there is benign: unlock_buffer() only use the bh's address for
119 * hashing after unlocking the buffer, so it doesn't actually touch the bh
120 * itself.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 */
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700122static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
124 if (uptodate) {
125 set_buffer_uptodate(bh);
126 } else {
127 /* This happens, due to failed READA attempts. */
128 clear_buffer_uptodate(bh);
129 }
130 unlock_buffer(bh);
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700131}
132
133/*
134 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
135 * unlock the buffer. This is what ll_rw_block uses too.
136 */
137void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
138{
139 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 put_bh(bh);
141}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700142EXPORT_SYMBOL(end_buffer_read_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
144void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
145{
146 char b[BDEVNAME_SIZE];
147
148 if (uptodate) {
149 set_buffer_uptodate(bh);
150 } else {
Christoph Hellwig0edd55f2010-08-18 05:29:23 -0400151 if (!quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 buffer_io_error(bh);
153 printk(KERN_WARNING "lost page write due to "
154 "I/O error on %s\n",
155 bdevname(bh->b_bdev, b));
156 }
157 set_buffer_write_io_error(bh);
158 clear_buffer_uptodate(bh);
159 }
160 unlock_buffer(bh);
161 put_bh(bh);
162}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700163EXPORT_SYMBOL(end_buffer_write_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
165/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 * Various filesystems appear to want __find_get_block to be non-blocking.
167 * But it's the page lock which protects the buffers. To get around this,
168 * we get exclusion from try_to_free_buffers with the blockdev mapping's
169 * private_lock.
170 *
171 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
172 * may be quite high. This code could TryLock the page, and if that
173 * succeeds, there is no need to take private_lock. (But if
174 * private_lock is contended then so is mapping->tree_lock).
175 */
176static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800177__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178{
179 struct inode *bd_inode = bdev->bd_inode;
180 struct address_space *bd_mapping = bd_inode->i_mapping;
181 struct buffer_head *ret = NULL;
182 pgoff_t index;
183 struct buffer_head *bh;
184 struct buffer_head *head;
185 struct page *page;
186 int all_mapped = 1;
187
188 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
189 page = find_get_page(bd_mapping, index);
190 if (!page)
191 goto out;
192
193 spin_lock(&bd_mapping->private_lock);
194 if (!page_has_buffers(page))
195 goto out_unlock;
196 head = page_buffers(page);
197 bh = head;
198 do {
Nikanth Karthikesan97f76d32009-04-02 16:56:46 -0700199 if (!buffer_mapped(bh))
200 all_mapped = 0;
201 else if (bh->b_blocknr == block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 ret = bh;
203 get_bh(bh);
204 goto out_unlock;
205 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 bh = bh->b_this_page;
207 } while (bh != head);
208
209 /* we might be here because some of the buffers on this page are
210 * not mapped. This is due to various races between
211 * file io on the block device and getblk. It gets dealt with
212 * elsewhere, don't buffer_error if we had some unmapped buffers
213 */
214 if (all_mapped) {
Tao Ma72a2ebd2011-10-31 17:09:00 -0700215 char b[BDEVNAME_SIZE];
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 printk("__find_get_block_slow() failed. "
218 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800219 (unsigned long long)block,
220 (unsigned long long)bh->b_blocknr);
221 printk("b_state=0x%08lx, b_size=%zu\n",
222 bh->b_state, bh->b_size);
Tao Ma72a2ebd2011-10-31 17:09:00 -0700223 printk("device %s blocksize: %d\n", bdevname(bdev, b),
224 1 << bd_inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 }
226out_unlock:
227 spin_unlock(&bd_mapping->private_lock);
228 page_cache_release(page);
229out:
230 return ret;
231}
232
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233/*
Jens Axboe5b0830c2009-09-23 19:37:09 +0200234 * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 */
236static void free_more_memory(void)
237{
Mel Gorman19770b32008-04-28 02:12:18 -0700238 struct zone *zone;
Mel Gorman0e884602008-04-28 02:12:14 -0700239 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240
Curt Wohlgemuth0e175a12011-10-07 21:54:10 -0600241 wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 yield();
243
Mel Gorman0e884602008-04-28 02:12:14 -0700244 for_each_online_node(nid) {
Mel Gorman19770b32008-04-28 02:12:18 -0700245 (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
246 gfp_zone(GFP_NOFS), NULL,
247 &zone);
248 if (zone)
Mel Gorman54a6eb52008-04-28 02:12:16 -0700249 try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700250 GFP_NOFS, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700251 }
252}
253
254/*
255 * I/O completion handler for block_read_full_page() - pages
256 * which come unlocked at the end of I/O.
257 */
258static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
259{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700261 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 struct buffer_head *tmp;
263 struct page *page;
264 int page_uptodate = 1;
265
266 BUG_ON(!buffer_async_read(bh));
267
268 page = bh->b_page;
269 if (uptodate) {
270 set_buffer_uptodate(bh);
271 } else {
272 clear_buffer_uptodate(bh);
Keith Mannthey08bafc02008-11-25 10:24:35 +0100273 if (!quiet_error(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 buffer_io_error(bh);
275 SetPageError(page);
276 }
277
278 /*
279 * Be _very_ careful from here on. Bad things can happen if
280 * two buffer heads end IO at almost the same time and both
281 * decide that the page is now completely done.
282 */
Nick Piggina3972202005-07-07 17:56:56 -0700283 first = page_buffers(page);
284 local_irq_save(flags);
285 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 clear_buffer_async_read(bh);
287 unlock_buffer(bh);
288 tmp = bh;
289 do {
290 if (!buffer_uptodate(tmp))
291 page_uptodate = 0;
292 if (buffer_async_read(tmp)) {
293 BUG_ON(!buffer_locked(tmp));
294 goto still_busy;
295 }
296 tmp = tmp->b_this_page;
297 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700298 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
299 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300
301 /*
302 * If none of the buffers had errors and they are all
303 * uptodate then we can set the page uptodate.
304 */
305 if (page_uptodate && !PageError(page))
306 SetPageUptodate(page);
307 unlock_page(page);
308 return;
309
310still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700311 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
312 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 return;
314}
315
316/*
317 * Completion handler for block_write_full_page() - pages which are unlocked
318 * during I/O, and which have PageWriteback cleared upon I/O completion.
319 */
Chris Mason35c80d52009-04-15 13:22:38 -0400320void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321{
322 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700324 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325 struct buffer_head *tmp;
326 struct page *page;
327
328 BUG_ON(!buffer_async_write(bh));
329
330 page = bh->b_page;
331 if (uptodate) {
332 set_buffer_uptodate(bh);
333 } else {
Keith Mannthey08bafc02008-11-25 10:24:35 +0100334 if (!quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 buffer_io_error(bh);
336 printk(KERN_WARNING "lost page write due to "
337 "I/O error on %s\n",
338 bdevname(bh->b_bdev, b));
339 }
340 set_bit(AS_EIO, &page->mapping->flags);
Jan Kara58ff4072006-10-17 00:10:19 -0700341 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 clear_buffer_uptodate(bh);
343 SetPageError(page);
344 }
345
Nick Piggina3972202005-07-07 17:56:56 -0700346 first = page_buffers(page);
347 local_irq_save(flags);
348 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
349
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 clear_buffer_async_write(bh);
351 unlock_buffer(bh);
352 tmp = bh->b_this_page;
353 while (tmp != bh) {
354 if (buffer_async_write(tmp)) {
355 BUG_ON(!buffer_locked(tmp));
356 goto still_busy;
357 }
358 tmp = tmp->b_this_page;
359 }
Nick Piggina3972202005-07-07 17:56:56 -0700360 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
361 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 end_page_writeback(page);
363 return;
364
365still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700366 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
367 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 return;
369}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700370EXPORT_SYMBOL(end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371
372/*
373 * If a page's buffers are under async readin (end_buffer_async_read
374 * completion) then there is a possibility that another thread of
375 * control could lock one of the buffers after it has completed
376 * but while some of the other buffers have not completed. This
377 * locked buffer would confuse end_buffer_async_read() into not unlocking
378 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
379 * that this buffer is not under async I/O.
380 *
381 * The page comes unlocked when it has no locked buffer_async buffers
382 * left.
383 *
384 * PageLocked prevents anyone starting new async I/O reads any of
385 * the buffers.
386 *
387 * PageWriteback is used to prevent simultaneous writeout of the same
388 * page.
389 *
390 * PageLocked prevents anyone from starting writeback of a page which is
391 * under read I/O (PageWriteback is only ever set against a locked page).
392 */
393static void mark_buffer_async_read(struct buffer_head *bh)
394{
395 bh->b_end_io = end_buffer_async_read;
396 set_buffer_async_read(bh);
397}
398
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700399static void mark_buffer_async_write_endio(struct buffer_head *bh,
400 bh_end_io_t *handler)
Chris Mason35c80d52009-04-15 13:22:38 -0400401{
402 bh->b_end_io = handler;
403 set_buffer_async_write(bh);
404}
405
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406void mark_buffer_async_write(struct buffer_head *bh)
407{
Chris Mason35c80d52009-04-15 13:22:38 -0400408 mark_buffer_async_write_endio(bh, end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409}
410EXPORT_SYMBOL(mark_buffer_async_write);
411
412
413/*
414 * fs/buffer.c contains helper functions for buffer-backed address space's
415 * fsync functions. A common requirement for buffer-based filesystems is
416 * that certain data from the backing blockdev needs to be written out for
417 * a successful fsync(). For example, ext2 indirect blocks need to be
418 * written back and waited upon before fsync() returns.
419 *
420 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
421 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
422 * management of a list of dependent buffers at ->i_mapping->private_list.
423 *
424 * Locking is a little subtle: try_to_free_buffers() will remove buffers
425 * from their controlling inode's queue when they are being freed. But
426 * try_to_free_buffers() will be operating against the *blockdev* mapping
427 * at the time, not against the S_ISREG file which depends on those buffers.
428 * So the locking for private_list is via the private_lock in the address_space
429 * which backs the buffers. Which is different from the address_space
430 * against which the buffers are listed. So for a particular address_space,
431 * mapping->private_lock does *not* protect mapping->private_list! In fact,
432 * mapping->private_list will always be protected by the backing blockdev's
433 * ->private_lock.
434 *
435 * Which introduces a requirement: all buffers on an address_space's
436 * ->private_list must be from the same address_space: the blockdev's.
437 *
438 * address_spaces which do not place buffers at ->private_list via these
439 * utility functions are free to use private_lock and private_list for
440 * whatever they want. The only requirement is that list_empty(private_list)
441 * be true at clear_inode() time.
442 *
443 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
444 * filesystems should do that. invalidate_inode_buffers() should just go
445 * BUG_ON(!list_empty).
446 *
447 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
448 * take an address_space, not an inode. And it should be called
449 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
450 * queued up.
451 *
452 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
453 * list if it is already on a list. Because if the buffer is on a list,
454 * it *must* already be on the right one. If not, the filesystem is being
455 * silly. This will save a ton of locking. But first we have to ensure
456 * that buffers are taken *off* the old inode's list when they are freed
457 * (presumably in truncate). That requires careful auditing of all
458 * filesystems (do it inside bforget()). It could also be done by bringing
459 * b_inode back.
460 */
461
462/*
463 * The buffer's backing address_space's private_lock must be held
464 */
Thomas Petazzonidbacefc2008-07-29 22:33:47 -0700465static void __remove_assoc_queue(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466{
467 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -0700468 WARN_ON(!bh->b_assoc_map);
469 if (buffer_write_io_error(bh))
470 set_bit(AS_EIO, &bh->b_assoc_map->flags);
471 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472}
473
474int inode_has_buffers(struct inode *inode)
475{
476 return !list_empty(&inode->i_data.private_list);
477}
478
479/*
480 * osync is designed to support O_SYNC io. It waits synchronously for
481 * all already-submitted IO to complete, but does not queue any new
482 * writes to the disk.
483 *
484 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
485 * you dirty the buffers, and then use osync_inode_buffers to wait for
486 * completion. Any other dirty buffers which are not yet queued for
487 * write will not be flushed to disk by the osync.
488 */
489static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
490{
491 struct buffer_head *bh;
492 struct list_head *p;
493 int err = 0;
494
495 spin_lock(lock);
496repeat:
497 list_for_each_prev(p, list) {
498 bh = BH_ENTRY(p);
499 if (buffer_locked(bh)) {
500 get_bh(bh);
501 spin_unlock(lock);
502 wait_on_buffer(bh);
503 if (!buffer_uptodate(bh))
504 err = -EIO;
505 brelse(bh);
506 spin_lock(lock);
507 goto repeat;
508 }
509 }
510 spin_unlock(lock);
511 return err;
512}
513
Al Viro01a05b32010-03-23 06:06:58 -0400514static void do_thaw_one(struct super_block *sb, void *unused)
515{
516 char b[BDEVNAME_SIZE];
517 while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
518 printk(KERN_WARNING "Emergency Thaw on %s\n",
519 bdevname(sb->s_bdev, b));
520}
521
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700522static void do_thaw_all(struct work_struct *work)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700523{
Al Viro01a05b32010-03-23 06:06:58 -0400524 iterate_supers(do_thaw_one, NULL);
Jens Axboe053c5252009-04-08 13:44:08 +0200525 kfree(work);
Eric Sandeenc2d75432009-03-31 15:23:46 -0700526 printk(KERN_WARNING "Emergency Thaw complete\n");
527}
528
529/**
530 * emergency_thaw_all -- forcibly thaw every frozen filesystem
531 *
532 * Used for emergency unfreeze of all filesystems via SysRq
533 */
534void emergency_thaw_all(void)
535{
Jens Axboe053c5252009-04-08 13:44:08 +0200536 struct work_struct *work;
537
538 work = kmalloc(sizeof(*work), GFP_ATOMIC);
539 if (work) {
540 INIT_WORK(work, do_thaw_all);
541 schedule_work(work);
542 }
Eric Sandeenc2d75432009-03-31 15:23:46 -0700543}
544
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800546 * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700547 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 *
549 * Starts I/O against the buffers at mapping->private_list, and waits upon
550 * that I/O.
551 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700552 * Basically, this is a convenience function for fsync().
553 * @mapping is a file or directory which needs those buffers to be written for
554 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700555 */
556int sync_mapping_buffers(struct address_space *mapping)
557{
558 struct address_space *buffer_mapping = mapping->assoc_mapping;
559
560 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
561 return 0;
562
563 return fsync_buffers_list(&buffer_mapping->private_lock,
564 &mapping->private_list);
565}
566EXPORT_SYMBOL(sync_mapping_buffers);
567
568/*
569 * Called when we've recently written block `bblock', and it is known that
570 * `bblock' was for a buffer_boundary() buffer. This means that the block at
571 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
572 * dirty, schedule it for IO. So that indirects merge nicely with their data.
573 */
574void write_boundary_block(struct block_device *bdev,
575 sector_t bblock, unsigned blocksize)
576{
577 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
578 if (bh) {
579 if (buffer_dirty(bh))
580 ll_rw_block(WRITE, 1, &bh);
581 put_bh(bh);
582 }
583}
584
585void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
586{
587 struct address_space *mapping = inode->i_mapping;
588 struct address_space *buffer_mapping = bh->b_page->mapping;
589
590 mark_buffer_dirty(bh);
591 if (!mapping->assoc_mapping) {
592 mapping->assoc_mapping = buffer_mapping;
593 } else {
Eric Sesterhenne827f922006-03-26 18:24:46 +0200594 BUG_ON(mapping->assoc_mapping != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595 }
Jan Kara535ee2f2008-02-08 04:21:59 -0800596 if (!bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 spin_lock(&buffer_mapping->private_lock);
598 list_move_tail(&bh->b_assoc_buffers,
599 &mapping->private_list);
Jan Kara58ff4072006-10-17 00:10:19 -0700600 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 spin_unlock(&buffer_mapping->private_lock);
602 }
603}
604EXPORT_SYMBOL(mark_buffer_dirty_inode);
605
606/*
Nick Piggin787d2212007-07-17 04:03:34 -0700607 * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
608 * dirty.
609 *
610 * If warn is true, then emit a warning if the page is not uptodate and has
611 * not been truncated.
612 */
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700613static void __set_page_dirty(struct page *page,
Nick Piggin787d2212007-07-17 04:03:34 -0700614 struct address_space *mapping, int warn)
615{
Nick Piggin19fd6232008-07-25 19:45:32 -0700616 spin_lock_irq(&mapping->tree_lock);
Nick Piggin787d2212007-07-17 04:03:34 -0700617 if (page->mapping) { /* Race with truncate? */
618 WARN_ON_ONCE(warn && !PageUptodate(page));
Edward Shishkine3a7cca2009-03-31 15:19:39 -0700619 account_page_dirtied(page, mapping);
Nick Piggin787d2212007-07-17 04:03:34 -0700620 radix_tree_tag_set(&mapping->page_tree,
621 page_index(page), PAGECACHE_TAG_DIRTY);
622 }
Nick Piggin19fd6232008-07-25 19:45:32 -0700623 spin_unlock_irq(&mapping->tree_lock);
Nick Piggin787d2212007-07-17 04:03:34 -0700624 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Nick Piggin787d2212007-07-17 04:03:34 -0700625}
626
627/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 * Add a page to the dirty page list.
629 *
630 * It is a sad fact of life that this function is called from several places
631 * deeply under spinlocking. It may not sleep.
632 *
633 * If the page has buffers, the uptodate buffers are set dirty, to preserve
634 * dirty-state coherency between the page and the buffers. It the page does
635 * not have buffers then when they are later attached they will all be set
636 * dirty.
637 *
638 * The buffers are dirtied before the page is dirtied. There's a small race
639 * window in which a writepage caller may see the page cleanness but not the
640 * buffer dirtiness. That's fine. If this code were to set the page dirty
641 * before the buffers, a concurrent writepage caller could clear the page dirty
642 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
643 * page on the dirty page list.
644 *
645 * We use private_lock to lock against try_to_free_buffers while using the
646 * page's buffer list. Also use this to protect against clean buffers being
647 * added to the page after it was set dirty.
648 *
649 * FIXME: may need to call ->reservepage here as well. That's rather up to the
650 * address_space though.
651 */
652int __set_page_dirty_buffers(struct page *page)
653{
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700654 int newly_dirty;
Nick Piggin787d2212007-07-17 04:03:34 -0700655 struct address_space *mapping = page_mapping(page);
Nick Pigginebf7a222006-10-10 04:36:54 +0200656
657 if (unlikely(!mapping))
658 return !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
660 spin_lock(&mapping->private_lock);
661 if (page_has_buffers(page)) {
662 struct buffer_head *head = page_buffers(page);
663 struct buffer_head *bh = head;
664
665 do {
666 set_buffer_dirty(bh);
667 bh = bh->b_this_page;
668 } while (bh != head);
669 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700670 newly_dirty = !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 spin_unlock(&mapping->private_lock);
672
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700673 if (newly_dirty)
674 __set_page_dirty(page, mapping, 1);
675 return newly_dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676}
677EXPORT_SYMBOL(__set_page_dirty_buffers);
678
679/*
680 * Write out and wait upon a list of buffers.
681 *
682 * We have conflicting pressures: we want to make sure that all
683 * initially dirty buffers get waited on, but that any subsequently
684 * dirtied buffers don't. After all, we don't want fsync to last
685 * forever if somebody is actively writing to the file.
686 *
687 * Do this in two main stages: first we copy dirty buffers to a
688 * temporary inode list, queueing the writes as we go. Then we clean
689 * up, waiting for those writes to complete.
690 *
691 * During this second stage, any subsequent updates to the file may end
692 * up refiling the buffer on the original inode's dirty list again, so
693 * there is a chance we will end up with a buffer queued for write but
694 * not yet completed on that list. So, as a final cleanup we go through
695 * the osync code to catch these locked, dirty buffers without requeuing
696 * any newly dirty buffers for write.
697 */
698static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
699{
700 struct buffer_head *bh;
701 struct list_head tmp;
Jens Axboe7eaceac2011-03-10 08:52:07 +0100702 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 int err = 0, err2;
Jens Axboe4ee24912011-03-17 10:51:40 +0100704 struct blk_plug plug;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705
706 INIT_LIST_HEAD(&tmp);
Jens Axboe4ee24912011-03-17 10:51:40 +0100707 blk_start_plug(&plug);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708
709 spin_lock(lock);
710 while (!list_empty(list)) {
711 bh = BH_ENTRY(list->next);
Jan Kara535ee2f2008-02-08 04:21:59 -0800712 mapping = bh->b_assoc_map;
Jan Kara58ff4072006-10-17 00:10:19 -0700713 __remove_assoc_queue(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800714 /* Avoid race with mark_buffer_dirty_inode() which does
715 * a lockless check and we rely on seeing the dirty bit */
716 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 if (buffer_dirty(bh) || buffer_locked(bh)) {
718 list_add(&bh->b_assoc_buffers, &tmp);
Jan Kara535ee2f2008-02-08 04:21:59 -0800719 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 if (buffer_dirty(bh)) {
721 get_bh(bh);
722 spin_unlock(lock);
723 /*
724 * Ensure any pending I/O completes so that
Christoph Hellwig9cb569d2010-08-11 17:06:24 +0200725 * write_dirty_buffer() actually writes the
726 * current contents - it is a noop if I/O is
727 * still in flight on potentially older
728 * contents.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 */
Jens Axboe721a9602011-03-09 11:56:30 +0100730 write_dirty_buffer(bh, WRITE_SYNC);
Jens Axboe9cf6b722009-04-06 14:48:03 +0200731
732 /*
733 * Kick off IO for the previous mapping. Note
734 * that we will not run the very last mapping,
735 * wait_on_buffer() will do that for us
736 * through sync_buffer().
737 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 brelse(bh);
739 spin_lock(lock);
740 }
741 }
742 }
743
Jens Axboe4ee24912011-03-17 10:51:40 +0100744 spin_unlock(lock);
745 blk_finish_plug(&plug);
746 spin_lock(lock);
747
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 while (!list_empty(&tmp)) {
749 bh = BH_ENTRY(tmp.prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750 get_bh(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800751 mapping = bh->b_assoc_map;
752 __remove_assoc_queue(bh);
753 /* Avoid race with mark_buffer_dirty_inode() which does
754 * a lockless check and we rely on seeing the dirty bit */
755 smp_mb();
756 if (buffer_dirty(bh)) {
757 list_add(&bh->b_assoc_buffers,
Jan Karae3892292008-03-04 14:28:33 -0800758 &mapping->private_list);
Jan Kara535ee2f2008-02-08 04:21:59 -0800759 bh->b_assoc_map = mapping;
760 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700761 spin_unlock(lock);
762 wait_on_buffer(bh);
763 if (!buffer_uptodate(bh))
764 err = -EIO;
765 brelse(bh);
766 spin_lock(lock);
767 }
768
769 spin_unlock(lock);
770 err2 = osync_buffers_list(lock, list);
771 if (err)
772 return err;
773 else
774 return err2;
775}
776
777/*
778 * Invalidate any and all dirty buffers on a given inode. We are
779 * probably unmounting the fs, but that doesn't mean we have already
780 * done a sync(). Just drop the buffers from the inode list.
781 *
782 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
783 * assumes that all the buffers are against the blockdev. Not true
784 * for reiserfs.
785 */
786void invalidate_inode_buffers(struct inode *inode)
787{
788 if (inode_has_buffers(inode)) {
789 struct address_space *mapping = &inode->i_data;
790 struct list_head *list = &mapping->private_list;
791 struct address_space *buffer_mapping = mapping->assoc_mapping;
792
793 spin_lock(&buffer_mapping->private_lock);
794 while (!list_empty(list))
795 __remove_assoc_queue(BH_ENTRY(list->next));
796 spin_unlock(&buffer_mapping->private_lock);
797 }
798}
Jan Kara52b19ac2008-09-23 18:24:08 +0200799EXPORT_SYMBOL(invalidate_inode_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
801/*
802 * Remove any clean buffers from the inode's buffer list. This is called
803 * when we're trying to free the inode itself. Those buffers can pin it.
804 *
805 * Returns true if all buffers were removed.
806 */
807int remove_inode_buffers(struct inode *inode)
808{
809 int ret = 1;
810
811 if (inode_has_buffers(inode)) {
812 struct address_space *mapping = &inode->i_data;
813 struct list_head *list = &mapping->private_list;
814 struct address_space *buffer_mapping = mapping->assoc_mapping;
815
816 spin_lock(&buffer_mapping->private_lock);
817 while (!list_empty(list)) {
818 struct buffer_head *bh = BH_ENTRY(list->next);
819 if (buffer_dirty(bh)) {
820 ret = 0;
821 break;
822 }
823 __remove_assoc_queue(bh);
824 }
825 spin_unlock(&buffer_mapping->private_lock);
826 }
827 return ret;
828}
829
830/*
831 * Create the appropriate buffers when given a page for data area and
832 * the size of each buffer.. Use the bh->b_this_page linked list to
833 * follow the buffers created. Return NULL if unable to create more
834 * buffers.
835 *
836 * The retry flag is used to differentiate async IO (paging, swapping)
837 * which may not fail from ordinary buffer allocations.
838 */
839struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
840 int retry)
841{
842 struct buffer_head *bh, *head;
843 long offset;
844
845try_again:
846 head = NULL;
847 offset = PAGE_SIZE;
848 while ((offset -= size) >= 0) {
849 bh = alloc_buffer_head(GFP_NOFS);
850 if (!bh)
851 goto no_grow;
852
853 bh->b_bdev = NULL;
854 bh->b_this_page = head;
855 bh->b_blocknr = -1;
856 head = bh;
857
858 bh->b_state = 0;
859 atomic_set(&bh->b_count, 0);
860 bh->b_size = size;
861
862 /* Link the buffer to its page */
863 set_bh_page(bh, page, offset);
864
Nathan Scott01ffe332006-01-17 09:02:07 +1100865 init_buffer(bh, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866 }
867 return head;
868/*
869 * In case anything failed, we just free everything we got.
870 */
871no_grow:
872 if (head) {
873 do {
874 bh = head;
875 head = head->b_this_page;
876 free_buffer_head(bh);
877 } while (head);
878 }
879
880 /*
881 * Return failure for non-async IO requests. Async IO requests
882 * are not allowed to fail, so we have to wait until buffer heads
883 * become available. But we don't want tasks sleeping with
884 * partially complete buffers, so all were released above.
885 */
886 if (!retry)
887 return NULL;
888
889 /* We're _really_ low on memory. Now we just
890 * wait for old buffer heads to become free due to
891 * finishing IO. Since this is an async request and
892 * the reserve list is empty, we're sure there are
893 * async buffer heads in use.
894 */
895 free_more_memory();
896 goto try_again;
897}
898EXPORT_SYMBOL_GPL(alloc_page_buffers);
899
900static inline void
901link_dev_buffers(struct page *page, struct buffer_head *head)
902{
903 struct buffer_head *bh, *tail;
904
905 bh = head;
906 do {
907 tail = bh;
908 bh = bh->b_this_page;
909 } while (bh);
910 tail->b_this_page = head;
911 attach_page_buffers(page, head);
912}
913
914/*
915 * Initialise the state of a blockdev page's buffers.
916 */
917static void
918init_page_buffers(struct page *page, struct block_device *bdev,
919 sector_t block, int size)
920{
921 struct buffer_head *head = page_buffers(page);
922 struct buffer_head *bh = head;
923 int uptodate = PageUptodate(page);
924
925 do {
926 if (!buffer_mapped(bh)) {
927 init_buffer(bh, NULL, NULL);
928 bh->b_bdev = bdev;
929 bh->b_blocknr = block;
930 if (uptodate)
931 set_buffer_uptodate(bh);
932 set_buffer_mapped(bh);
933 }
934 block++;
935 bh = bh->b_this_page;
936 } while (bh != head);
937}
938
939/*
940 * Create the page-cache page that contains the requested block.
941 *
942 * This is user purely for blockdev mappings.
943 */
944static struct page *
945grow_dev_page(struct block_device *bdev, sector_t block,
946 pgoff_t index, int size)
947{
948 struct inode *inode = bdev->bd_inode;
949 struct page *page;
950 struct buffer_head *bh;
951
Christoph Lameterea125892007-05-16 22:11:21 -0700952 page = find_or_create_page(inode->i_mapping, index,
Mel Gorman769848c2007-07-17 04:03:05 -0700953 (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 if (!page)
955 return NULL;
956
Eric Sesterhenne827f922006-03-26 18:24:46 +0200957 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958
959 if (page_has_buffers(page)) {
960 bh = page_buffers(page);
961 if (bh->b_size == size) {
962 init_page_buffers(page, bdev, block, size);
963 return page;
964 }
965 if (!try_to_free_buffers(page))
966 goto failed;
967 }
968
969 /*
970 * Allocate some buffers for this page
971 */
972 bh = alloc_page_buffers(page, size, 0);
973 if (!bh)
974 goto failed;
975
976 /*
977 * Link the page to the buffers and initialise them. Take the
978 * lock to be atomic wrt __find_get_block(), which does not
979 * run under the page lock.
980 */
981 spin_lock(&inode->i_mapping->private_lock);
982 link_dev_buffers(page, bh);
983 init_page_buffers(page, bdev, block, size);
984 spin_unlock(&inode->i_mapping->private_lock);
985 return page;
986
987failed:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 unlock_page(page);
989 page_cache_release(page);
990 return NULL;
991}
992
993/*
994 * Create buffers for the specified block device block's page. If
995 * that page was dirty, the buffers are set dirty also.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800997static int
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998grow_buffers(struct block_device *bdev, sector_t block, int size)
999{
1000 struct page *page;
1001 pgoff_t index;
1002 int sizebits;
1003
1004 sizebits = -1;
1005 do {
1006 sizebits++;
1007 } while ((size << sizebits) < PAGE_SIZE);
1008
1009 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010
Andrew Mortone5657932006-10-11 01:21:46 -07001011 /*
1012 * Check for a block which wants to lie outside our maximum possible
1013 * pagecache index. (this comparison is done using sector_t types).
1014 */
1015 if (unlikely(index != block >> sizebits)) {
1016 char b[BDEVNAME_SIZE];
1017
1018 printk(KERN_ERR "%s: requested out-of-range block %llu for "
1019 "device %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07001020 __func__, (unsigned long long)block,
Andrew Mortone5657932006-10-11 01:21:46 -07001021 bdevname(bdev, b));
1022 return -EIO;
1023 }
1024 block = index << sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025 /* Create a page with the proper size buffers.. */
1026 page = grow_dev_page(bdev, block, index, size);
1027 if (!page)
1028 return 0;
1029 unlock_page(page);
1030 page_cache_release(page);
1031 return 1;
1032}
1033
Adrian Bunk75c96f82005-05-05 16:16:09 -07001034static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035__getblk_slow(struct block_device *bdev, sector_t block, int size)
1036{
1037 /* Size must be multiple of hard sectorsize */
Martin K. Petersene1defc42009-05-22 17:17:49 -04001038 if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 (size < 512 || size > PAGE_SIZE))) {
1040 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1041 size);
Martin K. Petersene1defc42009-05-22 17:17:49 -04001042 printk(KERN_ERR "logical block size: %d\n",
1043 bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044
1045 dump_stack();
1046 return NULL;
1047 }
1048
1049 for (;;) {
1050 struct buffer_head * bh;
Andrew Mortone5657932006-10-11 01:21:46 -07001051 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052
1053 bh = __find_get_block(bdev, block, size);
1054 if (bh)
1055 return bh;
1056
Andrew Mortone5657932006-10-11 01:21:46 -07001057 ret = grow_buffers(bdev, block, size);
1058 if (ret < 0)
1059 return NULL;
1060 if (ret == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061 free_more_memory();
1062 }
1063}
1064
1065/*
1066 * The relationship between dirty buffers and dirty pages:
1067 *
1068 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1069 * the page is tagged dirty in its radix tree.
1070 *
1071 * At all times, the dirtiness of the buffers represents the dirtiness of
1072 * subsections of the page. If the page has buffers, the page dirty bit is
1073 * merely a hint about the true dirty state.
1074 *
1075 * When a page is set dirty in its entirety, all its buffers are marked dirty
1076 * (if the page has buffers).
1077 *
1078 * When a buffer is marked dirty, its page is dirtied, but the page's other
1079 * buffers are not.
1080 *
1081 * Also. When blockdev buffers are explicitly read with bread(), they
1082 * individually become uptodate. But their backing page remains not
1083 * uptodate - even if all of its buffers are uptodate. A subsequent
1084 * block_read_full_page() against that page will discover all the uptodate
1085 * buffers, will set the page uptodate and will perform no I/O.
1086 */
1087
1088/**
1089 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001090 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091 *
1092 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1093 * backing page dirty, then tag the page as dirty in its address_space's radix
1094 * tree and then attach the address_space's inode to its superblock's dirty
1095 * inode list.
1096 *
1097 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
Dave Chinner250df6e2011-03-22 22:23:36 +11001098 * mapping->tree_lock and mapping->host->i_lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001100void mark_buffer_dirty(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101{
Nick Piggin787d2212007-07-17 04:03:34 -07001102 WARN_ON_ONCE(!buffer_uptodate(bh));
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001103
1104 /*
1105 * Very *carefully* optimize the it-is-already-dirty case.
1106 *
1107 * Don't let the final "is it dirty" escape to before we
1108 * perhaps modified the buffer.
1109 */
1110 if (buffer_dirty(bh)) {
1111 smp_mb();
1112 if (buffer_dirty(bh))
1113 return;
1114 }
1115
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001116 if (!test_set_buffer_dirty(bh)) {
1117 struct page *page = bh->b_page;
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001118 if (!TestSetPageDirty(page)) {
1119 struct address_space *mapping = page_mapping(page);
1120 if (mapping)
1121 __set_page_dirty(page, mapping, 0);
1122 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001123 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001125EXPORT_SYMBOL(mark_buffer_dirty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126
1127/*
1128 * Decrement a buffer_head's reference count. If all buffers against a page
1129 * have zero reference count, are clean and unlocked, and if the page is clean
1130 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1131 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1132 * a page but it ends up not being freed, and buffers may later be reattached).
1133 */
1134void __brelse(struct buffer_head * buf)
1135{
1136 if (atomic_read(&buf->b_count)) {
1137 put_bh(buf);
1138 return;
1139 }
Arjan van de Ven5c752ad2008-07-25 19:45:40 -07001140 WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001142EXPORT_SYMBOL(__brelse);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143
1144/*
1145 * bforget() is like brelse(), except it discards any
1146 * potentially dirty data.
1147 */
1148void __bforget(struct buffer_head *bh)
1149{
1150 clear_buffer_dirty(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -08001151 if (bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001152 struct address_space *buffer_mapping = bh->b_page->mapping;
1153
1154 spin_lock(&buffer_mapping->private_lock);
1155 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -07001156 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001157 spin_unlock(&buffer_mapping->private_lock);
1158 }
1159 __brelse(bh);
1160}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001161EXPORT_SYMBOL(__bforget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162
1163static struct buffer_head *__bread_slow(struct buffer_head *bh)
1164{
1165 lock_buffer(bh);
1166 if (buffer_uptodate(bh)) {
1167 unlock_buffer(bh);
1168 return bh;
1169 } else {
1170 get_bh(bh);
1171 bh->b_end_io = end_buffer_read_sync;
1172 submit_bh(READ, bh);
1173 wait_on_buffer(bh);
1174 if (buffer_uptodate(bh))
1175 return bh;
1176 }
1177 brelse(bh);
1178 return NULL;
1179}
1180
1181/*
1182 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1183 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1184 * refcount elevated by one when they're in an LRU. A buffer can only appear
1185 * once in a particular CPU's LRU. A single buffer can be present in multiple
1186 * CPU's LRUs at the same time.
1187 *
1188 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1189 * sb_find_get_block().
1190 *
1191 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1192 * a local interrupt disable for that.
1193 */
1194
1195#define BH_LRU_SIZE 8
1196
1197struct bh_lru {
1198 struct buffer_head *bhs[BH_LRU_SIZE];
1199};
1200
1201static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1202
1203#ifdef CONFIG_SMP
1204#define bh_lru_lock() local_irq_disable()
1205#define bh_lru_unlock() local_irq_enable()
1206#else
1207#define bh_lru_lock() preempt_disable()
1208#define bh_lru_unlock() preempt_enable()
1209#endif
1210
1211static inline void check_irqs_on(void)
1212{
1213#ifdef irqs_disabled
1214 BUG_ON(irqs_disabled());
1215#endif
1216}
1217
1218/*
1219 * The LRU management algorithm is dopey-but-simple. Sorry.
1220 */
1221static void bh_lru_install(struct buffer_head *bh)
1222{
1223 struct buffer_head *evictee = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224
1225 check_irqs_on();
1226 bh_lru_lock();
Christoph Lameterc7b92512010-12-06 11:16:28 -06001227 if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001228 struct buffer_head *bhs[BH_LRU_SIZE];
1229 int in;
1230 int out = 0;
1231
1232 get_bh(bh);
1233 bhs[out++] = bh;
1234 for (in = 0; in < BH_LRU_SIZE; in++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001235 struct buffer_head *bh2 =
1236 __this_cpu_read(bh_lrus.bhs[in]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237
1238 if (bh2 == bh) {
1239 __brelse(bh2);
1240 } else {
1241 if (out >= BH_LRU_SIZE) {
1242 BUG_ON(evictee != NULL);
1243 evictee = bh2;
1244 } else {
1245 bhs[out++] = bh2;
1246 }
1247 }
1248 }
1249 while (out < BH_LRU_SIZE)
1250 bhs[out++] = NULL;
Christoph Lameterc7b92512010-12-06 11:16:28 -06001251 memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001252 }
1253 bh_lru_unlock();
1254
1255 if (evictee)
1256 __brelse(evictee);
1257}
1258
1259/*
1260 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1261 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001262static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001263lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264{
1265 struct buffer_head *ret = NULL;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001266 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001267
1268 check_irqs_on();
1269 bh_lru_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 for (i = 0; i < BH_LRU_SIZE; i++) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001271 struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272
1273 if (bh && bh->b_bdev == bdev &&
1274 bh->b_blocknr == block && bh->b_size == size) {
1275 if (i) {
1276 while (i) {
Christoph Lameterc7b92512010-12-06 11:16:28 -06001277 __this_cpu_write(bh_lrus.bhs[i],
1278 __this_cpu_read(bh_lrus.bhs[i - 1]));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279 i--;
1280 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06001281 __this_cpu_write(bh_lrus.bhs[0], bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 }
1283 get_bh(bh);
1284 ret = bh;
1285 break;
1286 }
1287 }
1288 bh_lru_unlock();
1289 return ret;
1290}
1291
1292/*
1293 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1294 * it in the LRU and mark it as accessed. If it is not present then return
1295 * NULL
1296 */
1297struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001298__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299{
1300 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1301
1302 if (bh == NULL) {
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001303 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 if (bh)
1305 bh_lru_install(bh);
1306 }
1307 if (bh)
1308 touch_buffer(bh);
1309 return bh;
1310}
1311EXPORT_SYMBOL(__find_get_block);
1312
1313/*
1314 * __getblk will locate (and, if necessary, create) the buffer_head
1315 * which corresponds to the passed block_device, block and size. The
1316 * returned buffer has its reference count incremented.
1317 *
1318 * __getblk() cannot fail - it just keeps trying. If you pass it an
1319 * illegal block number, __getblk() will happily return a buffer_head
1320 * which represents the non-existent block. Very weird.
1321 *
1322 * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1323 * attempt is failing. FIXME, perhaps?
1324 */
1325struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001326__getblk(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327{
1328 struct buffer_head *bh = __find_get_block(bdev, block, size);
1329
1330 might_sleep();
1331 if (bh == NULL)
1332 bh = __getblk_slow(bdev, block, size);
1333 return bh;
1334}
1335EXPORT_SYMBOL(__getblk);
1336
1337/*
1338 * Do async read-ahead on a buffer..
1339 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001340void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001341{
1342 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001343 if (likely(bh)) {
1344 ll_rw_block(READA, 1, &bh);
1345 brelse(bh);
1346 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347}
1348EXPORT_SYMBOL(__breadahead);
1349
1350/**
1351 * __bread() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001352 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 * @block: number of block
1354 * @size: size (in bytes) to read
1355 *
1356 * Reads a specified block, and returns buffer head that contains it.
1357 * It returns NULL if the block was unreadable.
1358 */
1359struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001360__bread(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361{
1362 struct buffer_head *bh = __getblk(bdev, block, size);
1363
Andrew Mortona3e713b2005-10-30 15:03:15 -08001364 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 bh = __bread_slow(bh);
1366 return bh;
1367}
1368EXPORT_SYMBOL(__bread);
1369
1370/*
1371 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1372 * This doesn't race because it runs in each cpu either in irq
1373 * or with preempt disabled.
1374 */
1375static void invalidate_bh_lru(void *arg)
1376{
1377 struct bh_lru *b = &get_cpu_var(bh_lrus);
1378 int i;
1379
1380 for (i = 0; i < BH_LRU_SIZE; i++) {
1381 brelse(b->bhs[i]);
1382 b->bhs[i] = NULL;
1383 }
1384 put_cpu_var(bh_lrus);
1385}
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001386
1387static bool has_bh_in_lru(int cpu, void *dummy)
1388{
1389 struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
1390 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001392 for (i = 0; i < BH_LRU_SIZE; i++) {
1393 if (b->bhs[i])
1394 return 1;
1395 }
1396
1397 return 0;
1398}
1399
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001400void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401{
Gilad Ben-Yossef42be35d2012-03-28 14:42:45 -07001402 on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403}
Nick Piggin9db55792008-02-08 04:19:49 -08001404EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405
1406void set_bh_page(struct buffer_head *bh,
1407 struct page *page, unsigned long offset)
1408{
1409 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001410 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 if (PageHighMem(page))
1412 /*
1413 * This catches illegal uses and preserves the offset:
1414 */
1415 bh->b_data = (char *)(0 + offset);
1416 else
1417 bh->b_data = page_address(page) + offset;
1418}
1419EXPORT_SYMBOL(set_bh_page);
1420
1421/*
1422 * Called when truncating a buffer on a page completely.
1423 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001424static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425{
1426 lock_buffer(bh);
1427 clear_buffer_dirty(bh);
1428 bh->b_bdev = NULL;
1429 clear_buffer_mapped(bh);
1430 clear_buffer_req(bh);
1431 clear_buffer_new(bh);
1432 clear_buffer_delay(bh);
David Chinner33a266d2007-02-12 00:51:41 -08001433 clear_buffer_unwritten(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 unlock_buffer(bh);
1435}
1436
1437/**
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001438 * block_invalidatepage - invalidate part or all of a buffer-backed page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439 *
1440 * @page: the page which is affected
1441 * @offset: the index of the truncation point
1442 *
1443 * block_invalidatepage() is called when all or part of the page has become
Wang Sheng-Hui814e1d22011-09-01 08:22:57 +08001444 * invalidated by a truncate operation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 *
1446 * block_invalidatepage() does not have to release all buffers, but it must
1447 * ensure that no dirty buffer is left outside @offset and that no I/O
1448 * is underway against any of the blocks which are outside the truncation
1449 * point. Because the caller is about to free (and possibly reuse) those
1450 * blocks on-disk.
1451 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001452void block_invalidatepage(struct page *page, unsigned long offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453{
1454 struct buffer_head *head, *bh, *next;
1455 unsigned int curr_off = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456
1457 BUG_ON(!PageLocked(page));
1458 if (!page_has_buffers(page))
1459 goto out;
1460
1461 head = page_buffers(page);
1462 bh = head;
1463 do {
1464 unsigned int next_off = curr_off + bh->b_size;
1465 next = bh->b_this_page;
1466
1467 /*
1468 * is this block fully invalidated?
1469 */
1470 if (offset <= curr_off)
1471 discard_buffer(bh);
1472 curr_off = next_off;
1473 bh = next;
1474 } while (bh != head);
1475
1476 /*
1477 * We release buffers only if the entire page is being invalidated.
1478 * The get_block cached value has been unconditionally invalidated,
1479 * so real IO is not possible anymore.
1480 */
1481 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001482 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001484 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001485}
1486EXPORT_SYMBOL(block_invalidatepage);
1487
1488/*
1489 * We attach and possibly dirty the buffers atomically wrt
1490 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1491 * is already excluded via the page lock.
1492 */
1493void create_empty_buffers(struct page *page,
1494 unsigned long blocksize, unsigned long b_state)
1495{
1496 struct buffer_head *bh, *head, *tail;
1497
1498 head = alloc_page_buffers(page, blocksize, 1);
1499 bh = head;
1500 do {
1501 bh->b_state |= b_state;
1502 tail = bh;
1503 bh = bh->b_this_page;
1504 } while (bh);
1505 tail->b_this_page = head;
1506
1507 spin_lock(&page->mapping->private_lock);
1508 if (PageUptodate(page) || PageDirty(page)) {
1509 bh = head;
1510 do {
1511 if (PageDirty(page))
1512 set_buffer_dirty(bh);
1513 if (PageUptodate(page))
1514 set_buffer_uptodate(bh);
1515 bh = bh->b_this_page;
1516 } while (bh != head);
1517 }
1518 attach_page_buffers(page, head);
1519 spin_unlock(&page->mapping->private_lock);
1520}
1521EXPORT_SYMBOL(create_empty_buffers);
1522
1523/*
1524 * We are taking a block for data and we don't want any output from any
1525 * buffer-cache aliases starting from return from that function and
1526 * until the moment when something will explicitly mark the buffer
1527 * dirty (hopefully that will not happen until we will free that block ;-)
1528 * We don't even need to mark it not-uptodate - nobody can expect
1529 * anything from a newly allocated buffer anyway. We used to used
1530 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1531 * don't want to mark the alias unmapped, for example - it would confuse
1532 * anyone who might pick it with bread() afterwards...
1533 *
1534 * Also.. Note that bforget() doesn't lock the buffer. So there can
1535 * be writeout I/O going on against recently-freed buffers. We don't
1536 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1537 * only if we really need to. That happens here.
1538 */
1539void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1540{
1541 struct buffer_head *old_bh;
1542
1543 might_sleep();
1544
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001545 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 if (old_bh) {
1547 clear_buffer_dirty(old_bh);
1548 wait_on_buffer(old_bh);
1549 clear_buffer_req(old_bh);
1550 __brelse(old_bh);
1551 }
1552}
1553EXPORT_SYMBOL(unmap_underlying_metadata);
1554
1555/*
1556 * NOTE! All mapped/uptodate combinations are valid:
1557 *
1558 * Mapped Uptodate Meaning
1559 *
1560 * No No "unknown" - must do get_block()
1561 * No Yes "hole" - zero-filled
1562 * Yes No "allocated" - allocated on disk, not read in
1563 * Yes Yes "valid" - allocated and up-to-date in memory.
1564 *
1565 * "Dirty" is valid only with the last case (mapped+uptodate).
1566 */
1567
1568/*
1569 * While block_write_full_page is writing back the dirty buffers under
1570 * the page lock, whoever dirtied the buffers may decide to clean them
1571 * again at any time. We handle that by only looking at the buffer
1572 * state inside lock_buffer().
1573 *
1574 * If block_write_full_page() is called for regular writeback
1575 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1576 * locked buffer. This only can happen if someone has written the buffer
1577 * directly, with submit_bh(). At the address_space level PageWriteback
1578 * prevents this contention from occurring.
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001579 *
1580 * If block_write_full_page() is called with wbc->sync_mode ==
Jens Axboe721a9602011-03-09 11:56:30 +01001581 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
1582 * causes the writes to be flagged as synchronous writes.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 */
1584static int __block_write_full_page(struct inode *inode, struct page *page,
Chris Mason35c80d52009-04-15 13:22:38 -04001585 get_block_t *get_block, struct writeback_control *wbc,
1586 bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587{
1588 int err;
1589 sector_t block;
1590 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001591 struct buffer_head *bh, *head;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001592 const unsigned blocksize = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 int nr_underway = 0;
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001594 int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
Jens Axboe721a9602011-03-09 11:56:30 +01001595 WRITE_SYNC : WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596
1597 BUG_ON(!PageLocked(page));
1598
1599 last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
1600
1601 if (!page_has_buffers(page)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001602 create_empty_buffers(page, blocksize,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 (1 << BH_Dirty)|(1 << BH_Uptodate));
1604 }
1605
1606 /*
1607 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1608 * here, and the (potentially unmapped) buffers may become dirty at
1609 * any time. If a buffer becomes dirty here after we've inspected it
1610 * then we just miss that fact, and the page stays dirty.
1611 *
1612 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1613 * handle that here by just cleaning them.
1614 */
1615
Andrew Morton54b21a72006-01-08 01:03:05 -08001616 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 head = page_buffers(page);
1618 bh = head;
1619
1620 /*
1621 * Get all the dirty buffers mapped to disk addresses and
1622 * handle any aliases from the underlying blockdev's mapping.
1623 */
1624 do {
1625 if (block > last_block) {
1626 /*
1627 * mapped buffers outside i_size will occur, because
1628 * this page can be outside i_size when there is a
1629 * truncate in progress.
1630 */
1631 /*
1632 * The buffer was zeroed by block_write_full_page()
1633 */
1634 clear_buffer_dirty(bh);
1635 set_buffer_uptodate(bh);
Alex Tomas29a814d2008-07-11 19:27:31 -04001636 } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
1637 buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001638 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001639 err = get_block(inode, block, bh, 1);
1640 if (err)
1641 goto recover;
Alex Tomas29a814d2008-07-11 19:27:31 -04001642 clear_buffer_delay(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001643 if (buffer_new(bh)) {
1644 /* blockdev mappings never come here */
1645 clear_buffer_new(bh);
1646 unmap_underlying_metadata(bh->b_bdev,
1647 bh->b_blocknr);
1648 }
1649 }
1650 bh = bh->b_this_page;
1651 block++;
1652 } while (bh != head);
1653
1654 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 if (!buffer_mapped(bh))
1656 continue;
1657 /*
1658 * If it's a fully non-blocking write attempt and we cannot
1659 * lock the buffer then redirty the page. Note that this can
Jens Axboe5b0830c2009-09-23 19:37:09 +02001660 * potentially cause a busy-wait loop from writeback threads
1661 * and kswapd activity, but those code paths have their own
1662 * higher-level throttling.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001663 */
Wu Fengguang1b430be2010-10-26 14:21:26 -07001664 if (wbc->sync_mode != WB_SYNC_NONE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001665 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02001666 } else if (!trylock_buffer(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001667 redirty_page_for_writepage(wbc, page);
1668 continue;
1669 }
1670 if (test_clear_buffer_dirty(bh)) {
Chris Mason35c80d52009-04-15 13:22:38 -04001671 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001672 } else {
1673 unlock_buffer(bh);
1674 }
1675 } while ((bh = bh->b_this_page) != head);
1676
1677 /*
1678 * The page and its buffers are protected by PageWriteback(), so we can
1679 * drop the bh refcounts early.
1680 */
1681 BUG_ON(PageWriteback(page));
1682 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683
1684 do {
1685 struct buffer_head *next = bh->b_this_page;
1686 if (buffer_async_write(bh)) {
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001687 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688 nr_underway++;
1689 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001690 bh = next;
1691 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001692 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693
1694 err = 0;
1695done:
1696 if (nr_underway == 0) {
1697 /*
1698 * The page was marked dirty, but the buffers were
1699 * clean. Someone wrote them back by hand with
1700 * ll_rw_block/submit_bh. A rare case.
1701 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001703
Linus Torvalds1da177e2005-04-16 15:20:36 -07001704 /*
1705 * The page and buffer_heads can be released at any time from
1706 * here on.
1707 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001708 }
1709 return err;
1710
1711recover:
1712 /*
1713 * ENOSPC, or some other error. We may already have added some
1714 * blocks to the file, so we need to write these out to avoid
1715 * exposing stale data.
1716 * The page is currently locked and not marked for writeback
1717 */
1718 bh = head;
1719 /* Recovery: lock and submit the mapped buffers */
1720 do {
Alex Tomas29a814d2008-07-11 19:27:31 -04001721 if (buffer_mapped(bh) && buffer_dirty(bh) &&
1722 !buffer_delay(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723 lock_buffer(bh);
Chris Mason35c80d52009-04-15 13:22:38 -04001724 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725 } else {
1726 /*
1727 * The buffer may have been set dirty during
1728 * attachment to a dirty page.
1729 */
1730 clear_buffer_dirty(bh);
1731 }
1732 } while ((bh = bh->b_this_page) != head);
1733 SetPageError(page);
1734 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001735 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 do {
1738 struct buffer_head *next = bh->b_this_page;
1739 if (buffer_async_write(bh)) {
1740 clear_buffer_dirty(bh);
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001741 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 nr_underway++;
1743 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 bh = next;
1745 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001746 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 goto done;
1748}
1749
Nick Pigginafddba42007-10-16 01:25:01 -07001750/*
1751 * If a page has any new buffers, zero them out here, and mark them uptodate
1752 * and dirty so they'll be written out (in order to prevent uninitialised
1753 * block data from leaking). And clear the new bit.
1754 */
1755void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1756{
1757 unsigned int block_start, block_end;
1758 struct buffer_head *head, *bh;
1759
1760 BUG_ON(!PageLocked(page));
1761 if (!page_has_buffers(page))
1762 return;
1763
1764 bh = head = page_buffers(page);
1765 block_start = 0;
1766 do {
1767 block_end = block_start + bh->b_size;
1768
1769 if (buffer_new(bh)) {
1770 if (block_end > from && block_start < to) {
1771 if (!PageUptodate(page)) {
1772 unsigned start, size;
1773
1774 start = max(from, block_start);
1775 size = min(to, block_end) - start;
1776
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001777 zero_user(page, start, size);
Nick Pigginafddba42007-10-16 01:25:01 -07001778 set_buffer_uptodate(bh);
1779 }
1780
1781 clear_buffer_new(bh);
1782 mark_buffer_dirty(bh);
1783 }
1784 }
1785
1786 block_start = block_end;
1787 bh = bh->b_this_page;
1788 } while (bh != head);
1789}
1790EXPORT_SYMBOL(page_zero_new_buffers);
1791
Christoph Hellwigebdec242010-10-06 10:47:23 +02001792int __block_write_begin(struct page *page, loff_t pos, unsigned len,
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001793 get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001794{
Christoph Hellwigebdec242010-10-06 10:47:23 +02001795 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1796 unsigned to = from + len;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001797 struct inode *inode = page->mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001798 unsigned block_start, block_end;
1799 sector_t block;
1800 int err = 0;
1801 unsigned blocksize, bbits;
1802 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1803
1804 BUG_ON(!PageLocked(page));
1805 BUG_ON(from > PAGE_CACHE_SIZE);
1806 BUG_ON(to > PAGE_CACHE_SIZE);
1807 BUG_ON(from > to);
1808
1809 blocksize = 1 << inode->i_blkbits;
1810 if (!page_has_buffers(page))
1811 create_empty_buffers(page, blocksize, 0);
1812 head = page_buffers(page);
1813
1814 bbits = inode->i_blkbits;
1815 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1816
1817 for(bh = head, block_start = 0; bh != head || !block_start;
1818 block++, block_start=block_end, bh = bh->b_this_page) {
1819 block_end = block_start + blocksize;
1820 if (block_end <= from || block_start >= to) {
1821 if (PageUptodate(page)) {
1822 if (!buffer_uptodate(bh))
1823 set_buffer_uptodate(bh);
1824 }
1825 continue;
1826 }
1827 if (buffer_new(bh))
1828 clear_buffer_new(bh);
1829 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001830 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831 err = get_block(inode, block, bh, 1);
1832 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001833 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001835 unmap_underlying_metadata(bh->b_bdev,
1836 bh->b_blocknr);
1837 if (PageUptodate(page)) {
Nick Piggin637aff42007-10-16 01:25:00 -07001838 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 set_buffer_uptodate(bh);
Nick Piggin637aff42007-10-16 01:25:00 -07001840 mark_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 continue;
1842 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001843 if (block_end > to || block_start < from)
1844 zero_user_segments(page,
1845 to, block_end,
1846 block_start, from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001847 continue;
1848 }
1849 }
1850 if (PageUptodate(page)) {
1851 if (!buffer_uptodate(bh))
1852 set_buffer_uptodate(bh);
1853 continue;
1854 }
1855 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08001856 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 (block_start < from || block_end > to)) {
1858 ll_rw_block(READ, 1, &bh);
1859 *wait_bh++=bh;
1860 }
1861 }
1862 /*
1863 * If we issued read requests - let them complete.
1864 */
1865 while(wait_bh > wait) {
1866 wait_on_buffer(*--wait_bh);
1867 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001868 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001869 }
Jan Karaf9f07b62011-06-14 00:58:27 +02001870 if (unlikely(err))
Nick Pigginafddba42007-10-16 01:25:01 -07001871 page_zero_new_buffers(page, from, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001872 return err;
1873}
Christoph Hellwigebdec242010-10-06 10:47:23 +02001874EXPORT_SYMBOL(__block_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875
1876static int __block_commit_write(struct inode *inode, struct page *page,
1877 unsigned from, unsigned to)
1878{
1879 unsigned block_start, block_end;
1880 int partial = 0;
1881 unsigned blocksize;
1882 struct buffer_head *bh, *head;
1883
1884 blocksize = 1 << inode->i_blkbits;
1885
1886 for(bh = head = page_buffers(page), block_start = 0;
1887 bh != head || !block_start;
1888 block_start=block_end, bh = bh->b_this_page) {
1889 block_end = block_start + blocksize;
1890 if (block_end <= from || block_start >= to) {
1891 if (!buffer_uptodate(bh))
1892 partial = 1;
1893 } else {
1894 set_buffer_uptodate(bh);
1895 mark_buffer_dirty(bh);
1896 }
Nick Pigginafddba42007-10-16 01:25:01 -07001897 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898 }
1899
1900 /*
1901 * If this is a partial write which happened to make all buffers
1902 * uptodate then we can optimize away a bogus readpage() for
1903 * the next read(). Here we 'discover' whether the page went
1904 * uptodate as a result of this (potentially partial) write.
1905 */
1906 if (!partial)
1907 SetPageUptodate(page);
1908 return 0;
1909}
1910
1911/*
Christoph Hellwig155130a2010-06-04 11:29:58 +02001912 * block_write_begin takes care of the basic task of block allocation and
1913 * bringing partial write blocks uptodate first.
1914 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10001915 * The filesystem needs to handle block truncation upon failure.
Nick Pigginafddba42007-10-16 01:25:01 -07001916 */
Christoph Hellwig155130a2010-06-04 11:29:58 +02001917int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
1918 unsigned flags, struct page **pagep, get_block_t *get_block)
Nick Pigginafddba42007-10-16 01:25:01 -07001919{
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001920 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
Nick Pigginafddba42007-10-16 01:25:01 -07001921 struct page *page;
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001922 int status;
Nick Pigginafddba42007-10-16 01:25:01 -07001923
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001924 page = grab_cache_page_write_begin(mapping, index, flags);
1925 if (!page)
1926 return -ENOMEM;
Nick Pigginafddba42007-10-16 01:25:01 -07001927
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001928 status = __block_write_begin(page, pos, len, get_block);
Nick Pigginafddba42007-10-16 01:25:01 -07001929 if (unlikely(status)) {
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001930 unlock_page(page);
1931 page_cache_release(page);
1932 page = NULL;
Nick Pigginafddba42007-10-16 01:25:01 -07001933 }
1934
Christoph Hellwig6e1db882010-06-04 11:29:57 +02001935 *pagep = page;
Nick Pigginafddba42007-10-16 01:25:01 -07001936 return status;
1937}
1938EXPORT_SYMBOL(block_write_begin);
1939
1940int block_write_end(struct file *file, struct address_space *mapping,
1941 loff_t pos, unsigned len, unsigned copied,
1942 struct page *page, void *fsdata)
1943{
1944 struct inode *inode = mapping->host;
1945 unsigned start;
1946
1947 start = pos & (PAGE_CACHE_SIZE - 1);
1948
1949 if (unlikely(copied < len)) {
1950 /*
1951 * The buffers that were written will now be uptodate, so we
1952 * don't have to worry about a readpage reading them and
1953 * overwriting a partial write. However if we have encountered
1954 * a short write and only partially written into a buffer, it
1955 * will not be marked uptodate, so a readpage might come in and
1956 * destroy our partial write.
1957 *
1958 * Do the simplest thing, and just treat any short write to a
1959 * non uptodate page as a zero-length write, and force the
1960 * caller to redo the whole thing.
1961 */
1962 if (!PageUptodate(page))
1963 copied = 0;
1964
1965 page_zero_new_buffers(page, start+copied, start+len);
1966 }
1967 flush_dcache_page(page);
1968
1969 /* This could be a short (even 0-length) commit */
1970 __block_commit_write(inode, page, start, start+copied);
1971
1972 return copied;
1973}
1974EXPORT_SYMBOL(block_write_end);
1975
1976int generic_write_end(struct file *file, struct address_space *mapping,
1977 loff_t pos, unsigned len, unsigned copied,
1978 struct page *page, void *fsdata)
1979{
1980 struct inode *inode = mapping->host;
Jan Karac7d206b2008-07-11 19:27:31 -04001981 int i_size_changed = 0;
Nick Pigginafddba42007-10-16 01:25:01 -07001982
1983 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1984
1985 /*
1986 * No need to use i_size_read() here, the i_size
1987 * cannot change under us because we hold i_mutex.
1988 *
1989 * But it's important to update i_size while still holding page lock:
1990 * page writeout could otherwise come in and zero beyond i_size.
1991 */
1992 if (pos+copied > inode->i_size) {
1993 i_size_write(inode, pos+copied);
Jan Karac7d206b2008-07-11 19:27:31 -04001994 i_size_changed = 1;
Nick Pigginafddba42007-10-16 01:25:01 -07001995 }
1996
1997 unlock_page(page);
1998 page_cache_release(page);
1999
Jan Karac7d206b2008-07-11 19:27:31 -04002000 /*
2001 * Don't mark the inode dirty under page lock. First, it unnecessarily
2002 * makes the holding time of page lock longer. Second, it forces lock
2003 * ordering of page lock and transaction start for journaling
2004 * filesystems.
2005 */
2006 if (i_size_changed)
2007 mark_inode_dirty(inode);
2008
Nick Pigginafddba42007-10-16 01:25:01 -07002009 return copied;
2010}
2011EXPORT_SYMBOL(generic_write_end);
2012
2013/*
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002014 * block_is_partially_uptodate checks whether buffers within a page are
2015 * uptodate or not.
2016 *
2017 * Returns true if all buffers which correspond to a file portion
2018 * we want to read are uptodate.
2019 */
2020int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
2021 unsigned long from)
2022{
2023 struct inode *inode = page->mapping->host;
2024 unsigned block_start, block_end, blocksize;
2025 unsigned to;
2026 struct buffer_head *bh, *head;
2027 int ret = 1;
2028
2029 if (!page_has_buffers(page))
2030 return 0;
2031
2032 blocksize = 1 << inode->i_blkbits;
2033 to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
2034 to = from + to;
2035 if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2036 return 0;
2037
2038 head = page_buffers(page);
2039 bh = head;
2040 block_start = 0;
2041 do {
2042 block_end = block_start + blocksize;
2043 if (block_end > from && block_start < to) {
2044 if (!buffer_uptodate(bh)) {
2045 ret = 0;
2046 break;
2047 }
2048 if (block_end >= to)
2049 break;
2050 }
2051 block_start = block_end;
2052 bh = bh->b_this_page;
2053 } while (bh != head);
2054
2055 return ret;
2056}
2057EXPORT_SYMBOL(block_is_partially_uptodate);
2058
2059/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060 * Generic "read page" function for block devices that have the normal
2061 * get_block functionality. This is most of the block device filesystems.
2062 * Reads the page asynchronously --- the unlock_buffer() and
2063 * set/clear_buffer_uptodate() functions propagate buffer state into the
2064 * page struct once IO has completed.
2065 */
2066int block_read_full_page(struct page *page, get_block_t *get_block)
2067{
2068 struct inode *inode = page->mapping->host;
2069 sector_t iblock, lblock;
2070 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
2071 unsigned int blocksize;
2072 int nr, i;
2073 int fully_mapped = 1;
2074
Matt Mackallcd7619d2005-05-01 08:59:01 -07002075 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002076 blocksize = 1 << inode->i_blkbits;
2077 if (!page_has_buffers(page))
2078 create_empty_buffers(page, blocksize, 0);
2079 head = page_buffers(page);
2080
2081 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2082 lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
2083 bh = head;
2084 nr = 0;
2085 i = 0;
2086
2087 do {
2088 if (buffer_uptodate(bh))
2089 continue;
2090
2091 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002092 int err = 0;
2093
Linus Torvalds1da177e2005-04-16 15:20:36 -07002094 fully_mapped = 0;
2095 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002096 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002097 err = get_block(inode, iblock, bh, 0);
2098 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002099 SetPageError(page);
2100 }
2101 if (!buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002102 zero_user(page, i * blocksize, blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002103 if (!err)
2104 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002105 continue;
2106 }
2107 /*
2108 * get_block() might have updated the buffer
2109 * synchronously
2110 */
2111 if (buffer_uptodate(bh))
2112 continue;
2113 }
2114 arr[nr++] = bh;
2115 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2116
2117 if (fully_mapped)
2118 SetPageMappedToDisk(page);
2119
2120 if (!nr) {
2121 /*
2122 * All buffers are uptodate - we can set the page uptodate
2123 * as well. But not if get_block() returned an error.
2124 */
2125 if (!PageError(page))
2126 SetPageUptodate(page);
2127 unlock_page(page);
2128 return 0;
2129 }
2130
2131 /* Stage two: lock the buffers */
2132 for (i = 0; i < nr; i++) {
2133 bh = arr[i];
2134 lock_buffer(bh);
2135 mark_buffer_async_read(bh);
2136 }
2137
2138 /*
2139 * Stage 3: start the IO. Check for uptodateness
2140 * inside the buffer lock in case another process reading
2141 * the underlying blockdev brought it uptodate (the sct fix).
2142 */
2143 for (i = 0; i < nr; i++) {
2144 bh = arr[i];
2145 if (buffer_uptodate(bh))
2146 end_buffer_async_read(bh, 1);
2147 else
2148 submit_bh(READ, bh);
2149 }
2150 return 0;
2151}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002152EXPORT_SYMBOL(block_read_full_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002153
2154/* utility function for filesystems that need to do work on expanding
Nick Piggin89e10782007-10-16 01:25:07 -07002155 * truncates. Uses filesystem pagecache writes to allow the filesystem to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002156 * deal with the hole.
2157 */
Nick Piggin89e10782007-10-16 01:25:07 -07002158int generic_cont_expand_simple(struct inode *inode, loff_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159{
2160 struct address_space *mapping = inode->i_mapping;
2161 struct page *page;
Nick Piggin89e10782007-10-16 01:25:07 -07002162 void *fsdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 int err;
2164
npiggin@suse.dec08d3b02009-08-21 02:35:06 +10002165 err = inode_newsize_ok(inode, size);
2166 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167 goto out;
2168
Nick Piggin89e10782007-10-16 01:25:07 -07002169 err = pagecache_write_begin(NULL, mapping, size, 0,
2170 AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2171 &page, &fsdata);
2172 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002173 goto out;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002174
Nick Piggin89e10782007-10-16 01:25:07 -07002175 err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2176 BUG_ON(err > 0);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002177
Linus Torvalds1da177e2005-04-16 15:20:36 -07002178out:
2179 return err;
2180}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002181EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002182
Adrian Bunkf1e3af72008-04-29 00:59:01 -07002183static int cont_expand_zero(struct file *file, struct address_space *mapping,
2184 loff_t pos, loff_t *bytes)
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002185{
Nick Piggin89e10782007-10-16 01:25:07 -07002186 struct inode *inode = mapping->host;
2187 unsigned blocksize = 1 << inode->i_blkbits;
2188 struct page *page;
2189 void *fsdata;
2190 pgoff_t index, curidx;
2191 loff_t curpos;
2192 unsigned zerofrom, offset, len;
2193 int err = 0;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002194
Nick Piggin89e10782007-10-16 01:25:07 -07002195 index = pos >> PAGE_CACHE_SHIFT;
2196 offset = pos & ~PAGE_CACHE_MASK;
2197
2198 while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2199 zerofrom = curpos & ~PAGE_CACHE_MASK;
2200 if (zerofrom & (blocksize-1)) {
2201 *bytes |= (blocksize-1);
2202 (*bytes)++;
2203 }
2204 len = PAGE_CACHE_SIZE - zerofrom;
2205
2206 err = pagecache_write_begin(file, mapping, curpos, len,
2207 AOP_FLAG_UNINTERRUPTIBLE,
2208 &page, &fsdata);
2209 if (err)
2210 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002211 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002212 err = pagecache_write_end(file, mapping, curpos, len, len,
2213 page, fsdata);
2214 if (err < 0)
2215 goto out;
2216 BUG_ON(err != len);
2217 err = 0;
OGAWA Hirofumi061e9742008-04-28 02:16:28 -07002218
2219 balance_dirty_pages_ratelimited(mapping);
Nick Piggin89e10782007-10-16 01:25:07 -07002220 }
2221
2222 /* page covers the boundary, find the boundary offset */
2223 if (index == curidx) {
2224 zerofrom = curpos & ~PAGE_CACHE_MASK;
2225 /* if we will expand the thing last block will be filled */
2226 if (offset <= zerofrom) {
2227 goto out;
2228 }
2229 if (zerofrom & (blocksize-1)) {
2230 *bytes |= (blocksize-1);
2231 (*bytes)++;
2232 }
2233 len = offset - zerofrom;
2234
2235 err = pagecache_write_begin(file, mapping, curpos, len,
2236 AOP_FLAG_UNINTERRUPTIBLE,
2237 &page, &fsdata);
2238 if (err)
2239 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002240 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002241 err = pagecache_write_end(file, mapping, curpos, len, len,
2242 page, fsdata);
2243 if (err < 0)
2244 goto out;
2245 BUG_ON(err != len);
2246 err = 0;
2247 }
2248out:
2249 return err;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002250}
2251
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252/*
2253 * For moronic filesystems that do not allow holes in file.
2254 * We may have to extend the file.
2255 */
Christoph Hellwig282dc172010-06-04 11:29:55 +02002256int cont_write_begin(struct file *file, struct address_space *mapping,
Nick Piggin89e10782007-10-16 01:25:07 -07002257 loff_t pos, unsigned len, unsigned flags,
2258 struct page **pagep, void **fsdata,
2259 get_block_t *get_block, loff_t *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002260{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 unsigned blocksize = 1 << inode->i_blkbits;
Nick Piggin89e10782007-10-16 01:25:07 -07002263 unsigned zerofrom;
2264 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002265
Nick Piggin89e10782007-10-16 01:25:07 -07002266 err = cont_expand_zero(file, mapping, pos, bytes);
2267 if (err)
Christoph Hellwig155130a2010-06-04 11:29:58 +02002268 return err;
Nick Piggin89e10782007-10-16 01:25:07 -07002269
2270 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2271 if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2272 *bytes |= (blocksize-1);
2273 (*bytes)++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274 }
2275
Christoph Hellwig155130a2010-06-04 11:29:58 +02002276 return block_write_begin(mapping, pos, len, flags, pagep, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002277}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002278EXPORT_SYMBOL(cont_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002279
Linus Torvalds1da177e2005-04-16 15:20:36 -07002280int block_commit_write(struct page *page, unsigned from, unsigned to)
2281{
2282 struct inode *inode = page->mapping->host;
2283 __block_commit_write(inode,page,from,to);
2284 return 0;
2285}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002286EXPORT_SYMBOL(block_commit_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002287
David Chinner54171692007-07-19 17:39:55 +10002288/*
2289 * block_page_mkwrite() is not allowed to change the file size as it gets
2290 * called from a page fault handler when a page is first dirtied. Hence we must
2291 * be careful to check for EOF conditions here. We set the page up correctly
2292 * for a written page which means we get ENOSPC checking when writing into
2293 * holes and correct delalloc and unwritten extent mapping on filesystems that
2294 * support these features.
2295 *
2296 * We are not allowed to take the i_mutex here so we have to play games to
2297 * protect against truncate races as the page could now be beyond EOF. Because
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002298 * truncate writes the inode size before removing pages, once we have the
David Chinner54171692007-07-19 17:39:55 +10002299 * page lock we can determine safely if the page is beyond EOF. If it is not
2300 * beyond EOF, then the page is guaranteed safe against truncation until we
2301 * unlock the page.
Jan Karaea13a862011-05-24 00:23:35 +02002302 *
2303 * Direct callers of this function should call vfs_check_frozen() so that page
2304 * fault does not busyloop until the fs is thawed.
David Chinner54171692007-07-19 17:39:55 +10002305 */
Jan Kara24da4fa2011-05-24 00:23:34 +02002306int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2307 get_block_t get_block)
David Chinner54171692007-07-19 17:39:55 +10002308{
Nick Pigginc2ec1752009-03-31 15:23:21 -07002309 struct page *page = vmf->page;
David Chinner54171692007-07-19 17:39:55 +10002310 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
2311 unsigned long end;
2312 loff_t size;
Jan Kara24da4fa2011-05-24 00:23:34 +02002313 int ret;
David Chinner54171692007-07-19 17:39:55 +10002314
2315 lock_page(page);
2316 size = i_size_read(inode);
2317 if ((page->mapping != inode->i_mapping) ||
Nick Piggin18336332007-07-20 00:31:45 -07002318 (page_offset(page) > size)) {
Jan Kara24da4fa2011-05-24 00:23:34 +02002319 /* We overload EFAULT to mean page got truncated */
2320 ret = -EFAULT;
2321 goto out_unlock;
David Chinner54171692007-07-19 17:39:55 +10002322 }
2323
2324 /* page is wholly or partially inside EOF */
2325 if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2326 end = size & ~PAGE_CACHE_MASK;
2327 else
2328 end = PAGE_CACHE_SIZE;
2329
Christoph Hellwigebdec242010-10-06 10:47:23 +02002330 ret = __block_write_begin(page, 0, end, get_block);
David Chinner54171692007-07-19 17:39:55 +10002331 if (!ret)
2332 ret = block_commit_write(page, 0, end);
2333
Jan Kara24da4fa2011-05-24 00:23:34 +02002334 if (unlikely(ret < 0))
2335 goto out_unlock;
Jan Karaea13a862011-05-24 00:23:35 +02002336 /*
2337 * Freezing in progress? We check after the page is marked dirty and
2338 * with page lock held so if the test here fails, we are sure freezing
2339 * code will wait during syncing until the page fault is done - at that
2340 * point page will be dirty and unlocked so freezing code will write it
2341 * and writeprotect it again.
2342 */
2343 set_page_dirty(page);
2344 if (inode->i_sb->s_frozen != SB_UNFROZEN) {
2345 ret = -EAGAIN;
2346 goto out_unlock;
2347 }
Darrick J. Wongd76ee182011-05-27 12:23:41 -07002348 wait_on_page_writeback(page);
Jan Kara24da4fa2011-05-24 00:23:34 +02002349 return 0;
2350out_unlock:
2351 unlock_page(page);
David Chinner54171692007-07-19 17:39:55 +10002352 return ret;
2353}
Jan Kara24da4fa2011-05-24 00:23:34 +02002354EXPORT_SYMBOL(__block_page_mkwrite);
2355
2356int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2357 get_block_t get_block)
2358{
Jan Karaea13a862011-05-24 00:23:35 +02002359 int ret;
2360 struct super_block *sb = vma->vm_file->f_path.dentry->d_inode->i_sb;
Jan Kara24da4fa2011-05-24 00:23:34 +02002361
Jan Karaea13a862011-05-24 00:23:35 +02002362 /*
2363 * This check is racy but catches the common case. The check in
2364 * __block_page_mkwrite() is reliable.
2365 */
2366 vfs_check_frozen(sb, SB_FREEZE_WRITE);
2367 ret = __block_page_mkwrite(vma, vmf, get_block);
Jan Kara24da4fa2011-05-24 00:23:34 +02002368 return block_page_mkwrite_return(ret);
2369}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002370EXPORT_SYMBOL(block_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371
2372/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002373 * nobh_write_begin()'s prereads are special: the buffer_heads are freed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374 * immediately, while under the page lock. So it needs a special end_io
2375 * handler which does not touch the bh after unlocking it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376 */
2377static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2378{
Dmitry Monakhov68671f32007-10-16 01:24:47 -07002379 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002380}
2381
2382/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002383 * Attach the singly-linked list of buffers created by nobh_write_begin, to
2384 * the page (converting it to circular linked list and taking care of page
2385 * dirty races).
2386 */
2387static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2388{
2389 struct buffer_head *bh;
2390
2391 BUG_ON(!PageLocked(page));
2392
2393 spin_lock(&page->mapping->private_lock);
2394 bh = head;
2395 do {
2396 if (PageDirty(page))
2397 set_buffer_dirty(bh);
2398 if (!bh->b_this_page)
2399 bh->b_this_page = head;
2400 bh = bh->b_this_page;
2401 } while (bh != head);
2402 attach_page_buffers(page, head);
2403 spin_unlock(&page->mapping->private_lock);
2404}
2405
2406/*
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002407 * On entry, the page is fully not uptodate.
2408 * On exit the page is fully uptodate in the areas outside (from,to)
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002409 * The filesystem needs to handle block truncation upon failure.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002410 */
Christoph Hellwigea0f04e2010-06-04 11:29:54 +02002411int nobh_write_begin(struct address_space *mapping,
Nick Piggin03158cd2007-10-16 01:25:25 -07002412 loff_t pos, unsigned len, unsigned flags,
2413 struct page **pagep, void **fsdata,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414 get_block_t *get_block)
2415{
Nick Piggin03158cd2007-10-16 01:25:25 -07002416 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002417 const unsigned blkbits = inode->i_blkbits;
2418 const unsigned blocksize = 1 << blkbits;
Nick Piggina4b06722007-10-16 01:24:48 -07002419 struct buffer_head *head, *bh;
Nick Piggin03158cd2007-10-16 01:25:25 -07002420 struct page *page;
2421 pgoff_t index;
2422 unsigned from, to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423 unsigned block_in_page;
Nick Piggina4b06722007-10-16 01:24:48 -07002424 unsigned block_start, block_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002425 sector_t block_in_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 int nr_reads = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 int ret = 0;
2428 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429
Nick Piggin03158cd2007-10-16 01:25:25 -07002430 index = pos >> PAGE_CACHE_SHIFT;
2431 from = pos & (PAGE_CACHE_SIZE - 1);
2432 to = from + len;
2433
Nick Piggin54566b22009-01-04 12:00:53 -08002434 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Piggin03158cd2007-10-16 01:25:25 -07002435 if (!page)
2436 return -ENOMEM;
2437 *pagep = page;
2438 *fsdata = NULL;
2439
2440 if (page_has_buffers(page)) {
Namhyung Kim309f77a2010-10-25 15:01:12 +09002441 ret = __block_write_begin(page, pos, len, get_block);
2442 if (unlikely(ret))
2443 goto out_release;
2444 return ret;
Nick Piggin03158cd2007-10-16 01:25:25 -07002445 }
Nick Piggina4b06722007-10-16 01:24:48 -07002446
Linus Torvalds1da177e2005-04-16 15:20:36 -07002447 if (PageMappedToDisk(page))
2448 return 0;
2449
Nick Piggina4b06722007-10-16 01:24:48 -07002450 /*
2451 * Allocate buffers so that we can keep track of state, and potentially
2452 * attach them to the page if an error occurs. In the common case of
2453 * no error, they will just be freed again without ever being attached
2454 * to the page (which is all OK, because we're under the page lock).
2455 *
2456 * Be careful: the buffer linked list is a NULL terminated one, rather
2457 * than the circular one we're used to.
2458 */
2459 head = alloc_page_buffers(page, blocksize, 0);
Nick Piggin03158cd2007-10-16 01:25:25 -07002460 if (!head) {
2461 ret = -ENOMEM;
2462 goto out_release;
2463 }
Nick Piggina4b06722007-10-16 01:24:48 -07002464
Linus Torvalds1da177e2005-04-16 15:20:36 -07002465 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002466
2467 /*
2468 * We loop across all blocks in the page, whether or not they are
2469 * part of the affected region. This is so we can discover if the
2470 * page is fully mapped-to-disk.
2471 */
Nick Piggina4b06722007-10-16 01:24:48 -07002472 for (block_start = 0, block_in_page = 0, bh = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473 block_start < PAGE_CACHE_SIZE;
Nick Piggina4b06722007-10-16 01:24:48 -07002474 block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002475 int create;
2476
Nick Piggina4b06722007-10-16 01:24:48 -07002477 block_end = block_start + blocksize;
2478 bh->b_state = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002479 create = 1;
2480 if (block_start >= to)
2481 create = 0;
2482 ret = get_block(inode, block_in_file + block_in_page,
Nick Piggina4b06722007-10-16 01:24:48 -07002483 bh, create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484 if (ret)
2485 goto failed;
Nick Piggina4b06722007-10-16 01:24:48 -07002486 if (!buffer_mapped(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487 is_mapped_to_disk = 0;
Nick Piggina4b06722007-10-16 01:24:48 -07002488 if (buffer_new(bh))
2489 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2490 if (PageUptodate(page)) {
2491 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002492 continue;
Nick Piggina4b06722007-10-16 01:24:48 -07002493 }
2494 if (buffer_new(bh) || !buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002495 zero_user_segments(page, block_start, from,
2496 to, block_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002497 continue;
2498 }
Nick Piggina4b06722007-10-16 01:24:48 -07002499 if (buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500 continue; /* reiserfs does this */
2501 if (block_start < from || block_end > to) {
Nick Piggina4b06722007-10-16 01:24:48 -07002502 lock_buffer(bh);
2503 bh->b_end_io = end_buffer_read_nobh;
2504 submit_bh(READ, bh);
2505 nr_reads++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002506 }
2507 }
2508
2509 if (nr_reads) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510 /*
2511 * The page is locked, so these buffers are protected from
2512 * any VM or truncate activity. Hence we don't need to care
2513 * for the buffer_head refcounts.
2514 */
Nick Piggina4b06722007-10-16 01:24:48 -07002515 for (bh = head; bh; bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516 wait_on_buffer(bh);
2517 if (!buffer_uptodate(bh))
2518 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002519 }
2520 if (ret)
2521 goto failed;
2522 }
2523
2524 if (is_mapped_to_disk)
2525 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002526
Nick Piggin03158cd2007-10-16 01:25:25 -07002527 *fsdata = head; /* to be released by nobh_write_end */
Nick Piggina4b06722007-10-16 01:24:48 -07002528
Linus Torvalds1da177e2005-04-16 15:20:36 -07002529 return 0;
2530
2531failed:
Nick Piggin03158cd2007-10-16 01:25:25 -07002532 BUG_ON(!ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533 /*
Nick Piggina4b06722007-10-16 01:24:48 -07002534 * Error recovery is a bit difficult. We need to zero out blocks that
2535 * were newly allocated, and dirty them to ensure they get written out.
2536 * Buffers need to be attached to the page at this point, otherwise
2537 * the handling of potential IO errors during writeout would be hard
2538 * (could try doing synchronous writeout, but what if that fails too?)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002539 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002540 attach_nobh_buffers(page, head);
2541 page_zero_new_buffers(page, from, to);
Nick Piggina4b06722007-10-16 01:24:48 -07002542
Nick Piggin03158cd2007-10-16 01:25:25 -07002543out_release:
2544 unlock_page(page);
2545 page_cache_release(page);
2546 *pagep = NULL;
Nick Piggina4b06722007-10-16 01:24:48 -07002547
npiggin@suse.de7bb46a62010-05-27 01:05:33 +10002548 return ret;
2549}
Nick Piggin03158cd2007-10-16 01:25:25 -07002550EXPORT_SYMBOL(nobh_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002551
Nick Piggin03158cd2007-10-16 01:25:25 -07002552int nobh_write_end(struct file *file, struct address_space *mapping,
2553 loff_t pos, unsigned len, unsigned copied,
2554 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555{
2556 struct inode *inode = page->mapping->host;
Nick Pigginefdc3132007-10-21 06:57:41 +02002557 struct buffer_head *head = fsdata;
Nick Piggin03158cd2007-10-16 01:25:25 -07002558 struct buffer_head *bh;
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002559 BUG_ON(fsdata != NULL && page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002560
Dave Kleikampd4cf1092009-02-06 14:59:26 -06002561 if (unlikely(copied < len) && head)
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002562 attach_nobh_buffers(page, head);
2563 if (page_has_buffers(page))
2564 return generic_write_end(file, mapping, pos, len,
2565 copied, page, fsdata);
Nick Piggina4b06722007-10-16 01:24:48 -07002566
Nick Piggin22c8ca72007-02-20 13:58:09 -08002567 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 set_page_dirty(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002569 if (pos+copied > inode->i_size) {
2570 i_size_write(inode, pos+copied);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571 mark_inode_dirty(inode);
2572 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002573
2574 unlock_page(page);
2575 page_cache_release(page);
2576
Nick Piggin03158cd2007-10-16 01:25:25 -07002577 while (head) {
2578 bh = head;
2579 head = head->b_this_page;
2580 free_buffer_head(bh);
2581 }
2582
2583 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002584}
Nick Piggin03158cd2007-10-16 01:25:25 -07002585EXPORT_SYMBOL(nobh_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002586
2587/*
2588 * nobh_writepage() - based on block_full_write_page() except
2589 * that it tries to operate without attaching bufferheads to
2590 * the page.
2591 */
2592int nobh_writepage(struct page *page, get_block_t *get_block,
2593 struct writeback_control *wbc)
2594{
2595 struct inode * const inode = page->mapping->host;
2596 loff_t i_size = i_size_read(inode);
2597 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2598 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 int ret;
2600
2601 /* Is the page fully inside i_size? */
2602 if (page->index < end_index)
2603 goto out;
2604
2605 /* Is the page fully outside i_size? (truncate in progress) */
2606 offset = i_size & (PAGE_CACHE_SIZE-1);
2607 if (page->index >= end_index+1 || !offset) {
2608 /*
2609 * The page may have dirty, unmapped buffers. For example,
2610 * they may have been added in ext3_writepage(). Make them
2611 * freeable here, so the page does not leak.
2612 */
2613#if 0
2614 /* Not really sure about this - do we need this ? */
2615 if (page->mapping->a_ops->invalidatepage)
2616 page->mapping->a_ops->invalidatepage(page, offset);
2617#endif
2618 unlock_page(page);
2619 return 0; /* don't care */
2620 }
2621
2622 /*
2623 * The page straddles i_size. It must be zeroed out on each and every
2624 * writepage invocation because it may be mmapped. "A file is mapped
2625 * in multiples of the page size. For a file that is not a multiple of
2626 * the page size, the remaining memory is zeroed when mapped, and
2627 * writes to that region are not written out to the file."
2628 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002629 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002630out:
2631 ret = mpage_writepage(page, get_block, wbc);
2632 if (ret == -EAGAIN)
Chris Mason35c80d52009-04-15 13:22:38 -04002633 ret = __block_write_full_page(inode, page, get_block, wbc,
2634 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002635 return ret;
2636}
2637EXPORT_SYMBOL(nobh_writepage);
2638
Nick Piggin03158cd2007-10-16 01:25:25 -07002639int nobh_truncate_page(struct address_space *mapping,
2640 loff_t from, get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002641{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002642 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2643 unsigned offset = from & (PAGE_CACHE_SIZE-1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002644 unsigned blocksize;
2645 sector_t iblock;
2646 unsigned length, pos;
2647 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002648 struct page *page;
Nick Piggin03158cd2007-10-16 01:25:25 -07002649 struct buffer_head map_bh;
2650 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002651
Nick Piggin03158cd2007-10-16 01:25:25 -07002652 blocksize = 1 << inode->i_blkbits;
2653 length = offset & (blocksize - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654
Nick Piggin03158cd2007-10-16 01:25:25 -07002655 /* Block boundary? Nothing to do */
2656 if (!length)
2657 return 0;
2658
2659 length = blocksize - length;
2660 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2661
Linus Torvalds1da177e2005-04-16 15:20:36 -07002662 page = grab_cache_page(mapping, index);
Nick Piggin03158cd2007-10-16 01:25:25 -07002663 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002664 if (!page)
2665 goto out;
2666
Nick Piggin03158cd2007-10-16 01:25:25 -07002667 if (page_has_buffers(page)) {
2668has_buffers:
2669 unlock_page(page);
2670 page_cache_release(page);
2671 return block_truncate_page(mapping, from, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002672 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002673
2674 /* Find the buffer that contains "offset" */
2675 pos = blocksize;
2676 while (offset >= pos) {
2677 iblock++;
2678 pos += blocksize;
2679 }
2680
Theodore Ts'o460bcf52009-05-12 07:37:56 -04002681 map_bh.b_size = blocksize;
2682 map_bh.b_state = 0;
Nick Piggin03158cd2007-10-16 01:25:25 -07002683 err = get_block(inode, iblock, &map_bh, 0);
2684 if (err)
2685 goto unlock;
2686 /* unmapped? It's a hole - nothing to do */
2687 if (!buffer_mapped(&map_bh))
2688 goto unlock;
2689
2690 /* Ok, it's mapped. Make sure it's up-to-date */
2691 if (!PageUptodate(page)) {
2692 err = mapping->a_ops->readpage(NULL, page);
2693 if (err) {
2694 page_cache_release(page);
2695 goto out;
2696 }
2697 lock_page(page);
2698 if (!PageUptodate(page)) {
2699 err = -EIO;
2700 goto unlock;
2701 }
2702 if (page_has_buffers(page))
2703 goto has_buffers;
2704 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002705 zero_user(page, offset, length);
Nick Piggin03158cd2007-10-16 01:25:25 -07002706 set_page_dirty(page);
2707 err = 0;
2708
2709unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002710 unlock_page(page);
2711 page_cache_release(page);
2712out:
Nick Piggin03158cd2007-10-16 01:25:25 -07002713 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002714}
2715EXPORT_SYMBOL(nobh_truncate_page);
2716
2717int block_truncate_page(struct address_space *mapping,
2718 loff_t from, get_block_t *get_block)
2719{
2720 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2721 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2722 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002723 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002724 unsigned length, pos;
2725 struct inode *inode = mapping->host;
2726 struct page *page;
2727 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002728 int err;
2729
2730 blocksize = 1 << inode->i_blkbits;
2731 length = offset & (blocksize - 1);
2732
2733 /* Block boundary? Nothing to do */
2734 if (!length)
2735 return 0;
2736
2737 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002738 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002739
2740 page = grab_cache_page(mapping, index);
2741 err = -ENOMEM;
2742 if (!page)
2743 goto out;
2744
2745 if (!page_has_buffers(page))
2746 create_empty_buffers(page, blocksize, 0);
2747
2748 /* Find the buffer that contains "offset" */
2749 bh = page_buffers(page);
2750 pos = blocksize;
2751 while (offset >= pos) {
2752 bh = bh->b_this_page;
2753 iblock++;
2754 pos += blocksize;
2755 }
2756
2757 err = 0;
2758 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002759 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002760 err = get_block(inode, iblock, bh, 0);
2761 if (err)
2762 goto unlock;
2763 /* unmapped? It's a hole - nothing to do */
2764 if (!buffer_mapped(bh))
2765 goto unlock;
2766 }
2767
2768 /* Ok, it's mapped. Make sure it's up-to-date */
2769 if (PageUptodate(page))
2770 set_buffer_uptodate(bh);
2771
David Chinner33a266d2007-02-12 00:51:41 -08002772 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002773 err = -EIO;
2774 ll_rw_block(READ, 1, &bh);
2775 wait_on_buffer(bh);
2776 /* Uhhuh. Read error. Complain and punt. */
2777 if (!buffer_uptodate(bh))
2778 goto unlock;
2779 }
2780
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002781 zero_user(page, offset, length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002782 mark_buffer_dirty(bh);
2783 err = 0;
2784
2785unlock:
2786 unlock_page(page);
2787 page_cache_release(page);
2788out:
2789 return err;
2790}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002791EXPORT_SYMBOL(block_truncate_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792
2793/*
2794 * The generic ->writepage function for buffer-backed address_spaces
Chris Mason35c80d52009-04-15 13:22:38 -04002795 * this form passes in the end_io handler used to finish the IO.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002796 */
Chris Mason35c80d52009-04-15 13:22:38 -04002797int block_write_full_page_endio(struct page *page, get_block_t *get_block,
2798 struct writeback_control *wbc, bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799{
2800 struct inode * const inode = page->mapping->host;
2801 loff_t i_size = i_size_read(inode);
2802 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2803 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002804
2805 /* Is the page fully inside i_size? */
2806 if (page->index < end_index)
Chris Mason35c80d52009-04-15 13:22:38 -04002807 return __block_write_full_page(inode, page, get_block, wbc,
2808 handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002809
2810 /* Is the page fully outside i_size? (truncate in progress) */
2811 offset = i_size & (PAGE_CACHE_SIZE-1);
2812 if (page->index >= end_index+1 || !offset) {
2813 /*
2814 * The page may have dirty, unmapped buffers. For example,
2815 * they may have been added in ext3_writepage(). Make them
2816 * freeable here, so the page does not leak.
2817 */
Jan Karaaaa40592005-10-30 15:00:16 -08002818 do_invalidatepage(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002819 unlock_page(page);
2820 return 0; /* don't care */
2821 }
2822
2823 /*
2824 * The page straddles i_size. It must be zeroed out on each and every
Adam Buchbinder2a61aa42009-12-11 16:35:40 -05002825 * writepage invocation because it may be mmapped. "A file is mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002826 * in multiples of the page size. For a file that is not a multiple of
2827 * the page size, the remaining memory is zeroed when mapped, and
2828 * writes to that region are not written out to the file."
2829 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002830 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Chris Mason35c80d52009-04-15 13:22:38 -04002831 return __block_write_full_page(inode, page, get_block, wbc, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002832}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002833EXPORT_SYMBOL(block_write_full_page_endio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002834
Chris Mason35c80d52009-04-15 13:22:38 -04002835/*
2836 * The generic ->writepage function for buffer-backed address_spaces
2837 */
2838int block_write_full_page(struct page *page, get_block_t *get_block,
2839 struct writeback_control *wbc)
2840{
2841 return block_write_full_page_endio(page, get_block, wbc,
2842 end_buffer_async_write);
2843}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002844EXPORT_SYMBOL(block_write_full_page);
Chris Mason35c80d52009-04-15 13:22:38 -04002845
Linus Torvalds1da177e2005-04-16 15:20:36 -07002846sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2847 get_block_t *get_block)
2848{
2849 struct buffer_head tmp;
2850 struct inode *inode = mapping->host;
2851 tmp.b_state = 0;
2852 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002853 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002854 get_block(inode, block, &tmp, 0);
2855 return tmp.b_blocknr;
2856}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002857EXPORT_SYMBOL(generic_block_bmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002858
NeilBrown6712ecf2007-09-27 12:47:43 +02002859static void end_bio_bh_io_sync(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002860{
2861 struct buffer_head *bh = bio->bi_private;
2862
Linus Torvalds1da177e2005-04-16 15:20:36 -07002863 if (err == -EOPNOTSUPP) {
2864 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002865 }
2866
Keith Mannthey08bafc02008-11-25 10:24:35 +01002867 if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2868 set_bit(BH_Quiet, &bh->b_state);
2869
Linus Torvalds1da177e2005-04-16 15:20:36 -07002870 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2871 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002872}
2873
2874int submit_bh(int rw, struct buffer_head * bh)
2875{
2876 struct bio *bio;
2877 int ret = 0;
2878
2879 BUG_ON(!buffer_locked(bh));
2880 BUG_ON(!buffer_mapped(bh));
2881 BUG_ON(!bh->b_end_io);
Aneesh Kumar K.V8fb0e342009-05-12 16:22:37 -04002882 BUG_ON(buffer_delay(bh));
2883 BUG_ON(buffer_unwritten(bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002884
Jens Axboe48fd4f92008-08-22 10:00:36 +02002885 /*
Jens Axboe48fd4f92008-08-22 10:00:36 +02002886 * Only clear out a write error when rewriting
Linus Torvalds1da177e2005-04-16 15:20:36 -07002887 */
Jens Axboe48fd4f92008-08-22 10:00:36 +02002888 if (test_set_buffer_req(bh) && (rw & WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002889 clear_buffer_write_io_error(bh);
2890
2891 /*
2892 * from here on down, it's all bio -- do the initial mapping,
2893 * submit_bio -> generic_make_request may further map this bio around
2894 */
2895 bio = bio_alloc(GFP_NOIO, 1);
2896
2897 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
2898 bio->bi_bdev = bh->b_bdev;
2899 bio->bi_io_vec[0].bv_page = bh->b_page;
2900 bio->bi_io_vec[0].bv_len = bh->b_size;
2901 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
2902
2903 bio->bi_vcnt = 1;
2904 bio->bi_idx = 0;
2905 bio->bi_size = bh->b_size;
2906
2907 bio->bi_end_io = end_bio_bh_io_sync;
2908 bio->bi_private = bh;
2909
2910 bio_get(bio);
2911 submit_bio(rw, bio);
2912
2913 if (bio_flagged(bio, BIO_EOPNOTSUPP))
2914 ret = -EOPNOTSUPP;
2915
2916 bio_put(bio);
2917 return ret;
2918}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002919EXPORT_SYMBOL(submit_bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920
2921/**
2922 * ll_rw_block: low-level access to block devices (DEPRECATED)
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002923 * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002924 * @nr: number of &struct buffer_heads in the array
2925 * @bhs: array of pointers to &struct buffer_head
2926 *
Jan Karaa7662232005-09-06 15:19:10 -07002927 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
2928 * requests an I/O operation on them, either a %READ or a %WRITE. The third
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002929 * %READA option is described in the documentation for generic_make_request()
2930 * which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002931 *
2932 * This function drops any buffer that it cannot get a lock on (with the
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002933 * BH_Lock state bit), any buffer that appears to be clean when doing a write
2934 * request, and any buffer that appears to be up-to-date when doing read
2935 * request. Further it marks as clean buffers that are processed for
2936 * writing (the buffer cache won't assume that they are actually clean
2937 * until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002938 *
2939 * ll_rw_block sets b_end_io to simple completion handler that marks
2940 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
2941 * any waiters.
2942 *
2943 * All of the buffers must be for the same device, and must also be a
2944 * multiple of the current approved size for the device.
2945 */
2946void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
2947{
2948 int i;
2949
2950 for (i = 0; i < nr; i++) {
2951 struct buffer_head *bh = bhs[i];
2952
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002953 if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002954 continue;
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002955 if (rw == WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002956 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07002957 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08002958 get_bh(bh);
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002959 submit_bh(WRITE, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960 continue;
2961 }
2962 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002963 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07002964 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08002965 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002966 submit_bh(rw, bh);
2967 continue;
2968 }
2969 }
2970 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002971 }
2972}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002973EXPORT_SYMBOL(ll_rw_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002974
Christoph Hellwig9cb569d2010-08-11 17:06:24 +02002975void write_dirty_buffer(struct buffer_head *bh, int rw)
2976{
2977 lock_buffer(bh);
2978 if (!test_clear_buffer_dirty(bh)) {
2979 unlock_buffer(bh);
2980 return;
2981 }
2982 bh->b_end_io = end_buffer_write_sync;
2983 get_bh(bh);
2984 submit_bh(rw, bh);
2985}
2986EXPORT_SYMBOL(write_dirty_buffer);
2987
Linus Torvalds1da177e2005-04-16 15:20:36 -07002988/*
2989 * For a data-integrity writeout, we need to wait upon any in-progress I/O
2990 * and then start new I/O and then wait upon it. The caller must have a ref on
2991 * the buffer_head.
2992 */
Christoph Hellwig87e99512010-08-11 17:05:45 +02002993int __sync_dirty_buffer(struct buffer_head *bh, int rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002994{
2995 int ret = 0;
2996
2997 WARN_ON(atomic_read(&bh->b_count) < 1);
2998 lock_buffer(bh);
2999 if (test_clear_buffer_dirty(bh)) {
3000 get_bh(bh);
3001 bh->b_end_io = end_buffer_write_sync;
Christoph Hellwig87e99512010-08-11 17:05:45 +02003002 ret = submit_bh(rw, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003003 wait_on_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003004 if (!ret && !buffer_uptodate(bh))
3005 ret = -EIO;
3006 } else {
3007 unlock_buffer(bh);
3008 }
3009 return ret;
3010}
Christoph Hellwig87e99512010-08-11 17:05:45 +02003011EXPORT_SYMBOL(__sync_dirty_buffer);
3012
3013int sync_dirty_buffer(struct buffer_head *bh)
3014{
3015 return __sync_dirty_buffer(bh, WRITE_SYNC);
3016}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003017EXPORT_SYMBOL(sync_dirty_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003018
3019/*
3020 * try_to_free_buffers() checks if all the buffers on this particular page
3021 * are unused, and releases them if so.
3022 *
3023 * Exclusion against try_to_free_buffers may be obtained by either
3024 * locking the page or by holding its mapping's private_lock.
3025 *
3026 * If the page is dirty but all the buffers are clean then we need to
3027 * be sure to mark the page clean as well. This is because the page
3028 * may be against a block device, and a later reattachment of buffers
3029 * to a dirty page will set *all* buffers dirty. Which would corrupt
3030 * filesystem data on the same device.
3031 *
3032 * The same applies to regular filesystem pages: if all the buffers are
3033 * clean then we set the page clean and proceed. To do that, we require
3034 * total exclusion from __set_page_dirty_buffers(). That is obtained with
3035 * private_lock.
3036 *
3037 * try_to_free_buffers() is non-blocking.
3038 */
3039static inline int buffer_busy(struct buffer_head *bh)
3040{
3041 return atomic_read(&bh->b_count) |
3042 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3043}
3044
3045static int
3046drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3047{
3048 struct buffer_head *head = page_buffers(page);
3049 struct buffer_head *bh;
3050
3051 bh = head;
3052 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07003053 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003054 set_bit(AS_EIO, &page->mapping->flags);
3055 if (buffer_busy(bh))
3056 goto failed;
3057 bh = bh->b_this_page;
3058 } while (bh != head);
3059
3060 do {
3061 struct buffer_head *next = bh->b_this_page;
3062
Jan Kara535ee2f2008-02-08 04:21:59 -08003063 if (bh->b_assoc_map)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003064 __remove_assoc_queue(bh);
3065 bh = next;
3066 } while (bh != head);
3067 *buffers_to_free = head;
3068 __clear_page_buffers(page);
3069 return 1;
3070failed:
3071 return 0;
3072}
3073
3074int try_to_free_buffers(struct page *page)
3075{
3076 struct address_space * const mapping = page->mapping;
3077 struct buffer_head *buffers_to_free = NULL;
3078 int ret = 0;
3079
3080 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003081 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003082 return 0;
3083
3084 if (mapping == NULL) { /* can this still happen? */
3085 ret = drop_buffers(page, &buffers_to_free);
3086 goto out;
3087 }
3088
3089 spin_lock(&mapping->private_lock);
3090 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003091
3092 /*
3093 * If the filesystem writes its buffers by hand (eg ext3)
3094 * then we can have clean buffers against a dirty page. We
3095 * clean the page here; otherwise the VM will never notice
3096 * that the filesystem did any IO at all.
3097 *
3098 * Also, during truncate, discard_buffer will have marked all
3099 * the page's buffers clean. We discover that here and clean
3100 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11003101 *
3102 * private_lock must be held over this entire operation in order
3103 * to synchronise against __set_page_dirty_buffers and prevent the
3104 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003105 */
3106 if (ret)
3107 cancel_dirty_page(page, PAGE_CACHE_SIZE);
Nick Piggin87df7242007-01-30 14:36:27 +11003108 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003109out:
3110 if (buffers_to_free) {
3111 struct buffer_head *bh = buffers_to_free;
3112
3113 do {
3114 struct buffer_head *next = bh->b_this_page;
3115 free_buffer_head(bh);
3116 bh = next;
3117 } while (bh != buffers_to_free);
3118 }
3119 return ret;
3120}
3121EXPORT_SYMBOL(try_to_free_buffers);
3122
Linus Torvalds1da177e2005-04-16 15:20:36 -07003123/*
3124 * There are no bdflush tunables left. But distributions are
3125 * still running obsolete flush daemons, so we terminate them here.
3126 *
3127 * Use of bdflush() is deprecated and will be removed in a future kernel.
Jens Axboe5b0830c2009-09-23 19:37:09 +02003128 * The `flush-X' kernel threads fully replace bdflush daemons and this call.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003129 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01003130SYSCALL_DEFINE2(bdflush, int, func, long, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003131{
3132 static int msg_count;
3133
3134 if (!capable(CAP_SYS_ADMIN))
3135 return -EPERM;
3136
3137 if (msg_count < 5) {
3138 msg_count++;
3139 printk(KERN_INFO
3140 "warning: process `%s' used the obsolete bdflush"
3141 " system call\n", current->comm);
3142 printk(KERN_INFO "Fix your initscripts?\n");
3143 }
3144
3145 if (func == 1)
3146 do_exit(0);
3147 return 0;
3148}
3149
3150/*
3151 * Buffer-head allocation
3152 */
Christoph Lametere18b8902006-12-06 20:33:20 -08003153static struct kmem_cache *bh_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003154
3155/*
3156 * Once the number of bh's in the machine exceeds this level, we start
3157 * stripping them in writeback.
3158 */
3159static int max_buffer_heads;
3160
3161int buffer_heads_over_limit;
3162
3163struct bh_accounting {
3164 int nr; /* Number of live bh's */
3165 int ratelimit; /* Limit cacheline bouncing */
3166};
3167
3168static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3169
3170static void recalc_bh_state(void)
3171{
3172 int i;
3173 int tot = 0;
3174
Christoph Lameteree1be862010-12-06 11:40:05 -06003175 if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003176 return;
Christoph Lameterc7b92512010-12-06 11:16:28 -06003177 __this_cpu_write(bh_accounting.ratelimit, 0);
Eric Dumazet8a143422006-03-24 03:18:10 -08003178 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003179 tot += per_cpu(bh_accounting, i).nr;
3180 buffer_heads_over_limit = (tot > max_buffer_heads);
3181}
Christoph Lameterc7b92512010-12-06 11:16:28 -06003182
Al Virodd0fc662005-10-07 07:46:04 +01003183struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003184{
Richard Kennedy019b4d12010-03-10 15:20:33 -08003185 struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003186 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07003187 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003188 preempt_disable();
3189 __this_cpu_inc(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003190 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003191 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003192 }
3193 return ret;
3194}
3195EXPORT_SYMBOL(alloc_buffer_head);
3196
3197void free_buffer_head(struct buffer_head *bh)
3198{
3199 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3200 kmem_cache_free(bh_cachep, bh);
Christoph Lameterc7b92512010-12-06 11:16:28 -06003201 preempt_disable();
3202 __this_cpu_dec(bh_accounting.nr);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003203 recalc_bh_state();
Christoph Lameterc7b92512010-12-06 11:16:28 -06003204 preempt_enable();
Linus Torvalds1da177e2005-04-16 15:20:36 -07003205}
3206EXPORT_SYMBOL(free_buffer_head);
3207
Linus Torvalds1da177e2005-04-16 15:20:36 -07003208static void buffer_exit_cpu(int cpu)
3209{
3210 int i;
3211 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3212
3213 for (i = 0; i < BH_LRU_SIZE; i++) {
3214 brelse(b->bhs[i]);
3215 b->bhs[i] = NULL;
3216 }
Christoph Lameterc7b92512010-12-06 11:16:28 -06003217 this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
Eric Dumazet8a143422006-03-24 03:18:10 -08003218 per_cpu(bh_accounting, cpu).nr = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003219}
3220
3221static int buffer_cpu_notify(struct notifier_block *self,
3222 unsigned long action, void *hcpu)
3223{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003224 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003225 buffer_exit_cpu((unsigned long)hcpu);
3226 return NOTIFY_OK;
3227}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003228
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003229/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003230 * bh_uptodate_or_lock - Test whether the buffer is uptodate
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003231 * @bh: struct buffer_head
3232 *
3233 * Return true if the buffer is up-to-date and false,
3234 * with the buffer locked, if not.
3235 */
3236int bh_uptodate_or_lock(struct buffer_head *bh)
3237{
3238 if (!buffer_uptodate(bh)) {
3239 lock_buffer(bh);
3240 if (!buffer_uptodate(bh))
3241 return 0;
3242 unlock_buffer(bh);
3243 }
3244 return 1;
3245}
3246EXPORT_SYMBOL(bh_uptodate_or_lock);
3247
3248/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003249 * bh_submit_read - Submit a locked buffer for reading
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003250 * @bh: struct buffer_head
3251 *
3252 * Returns zero on success and -EIO on error.
3253 */
3254int bh_submit_read(struct buffer_head *bh)
3255{
3256 BUG_ON(!buffer_locked(bh));
3257
3258 if (buffer_uptodate(bh)) {
3259 unlock_buffer(bh);
3260 return 0;
3261 }
3262
3263 get_bh(bh);
3264 bh->b_end_io = end_buffer_read_sync;
3265 submit_bh(READ, bh);
3266 wait_on_buffer(bh);
3267 if (buffer_uptodate(bh))
3268 return 0;
3269 return -EIO;
3270}
3271EXPORT_SYMBOL(bh_submit_read);
3272
Linus Torvalds1da177e2005-04-16 15:20:36 -07003273void __init buffer_init(void)
3274{
3275 int nrpages;
3276
Christoph Lameterb98938c2008-02-04 22:28:36 -08003277 bh_cachep = kmem_cache_create("buffer_head",
3278 sizeof(struct buffer_head), 0,
3279 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3280 SLAB_MEM_SPREAD),
Richard Kennedy019b4d12010-03-10 15:20:33 -08003281 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003282
3283 /*
3284 * Limit the bh occupancy to 10% of ZONE_NORMAL
3285 */
3286 nrpages = (nr_free_buffer_pages() * 10) / 100;
3287 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3288 hotcpu_notifier(buffer_cpu_notify, 0);
3289}