blob: e8aa7081d25c533d0548da7755114802b3706a9b [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>
32#include <linux/module.h>
33#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
57static int sync_buffer(void *word)
58{
59 struct block_device *bd;
60 struct buffer_head *bh
61 = container_of(word, struct buffer_head, b_state);
62
63 smp_mb();
64 bd = bh->b_bdev;
65 if (bd)
66 blk_run_address_space(bd->bd_inode->i_mapping);
67 io_schedule();
68 return 0;
69}
70
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080071void __lock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070072{
73 wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer,
74 TASK_UNINTERRUPTIBLE);
75}
76EXPORT_SYMBOL(__lock_buffer);
77
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080078void unlock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070079{
Nick Piggin51b07fc2008-10-18 20:27:00 -070080 clear_bit_unlock(BH_Lock, &bh->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 smp_mb__after_clear_bit();
82 wake_up_bit(&bh->b_state, BH_Lock);
83}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070084EXPORT_SYMBOL(unlock_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070085
86/*
87 * Block until a buffer comes unlocked. This doesn't stop it
88 * from becoming locked again - you have to lock it yourself
89 * if you want to preserve its state.
90 */
91void __wait_on_buffer(struct buffer_head * bh)
92{
93 wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE);
94}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -070095EXPORT_SYMBOL(__wait_on_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
97static void
98__clear_page_buffers(struct page *page)
99{
100 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700101 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 page_cache_release(page);
103}
104
Keith Mannthey08bafc02008-11-25 10:24:35 +0100105
106static int quiet_error(struct buffer_head *bh)
107{
108 if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
109 return 0;
110 return 1;
111}
112
113
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114static void buffer_io_error(struct buffer_head *bh)
115{
116 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
118 bdevname(bh->b_bdev, b),
119 (unsigned long long)bh->b_blocknr);
120}
121
122/*
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700123 * End-of-IO handler helper function which does not touch the bh after
124 * unlocking it.
125 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
126 * a race there is benign: unlock_buffer() only use the bh's address for
127 * hashing after unlocking the buffer, so it doesn't actually touch the bh
128 * itself.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 */
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700130static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131{
132 if (uptodate) {
133 set_buffer_uptodate(bh);
134 } else {
135 /* This happens, due to failed READA attempts. */
136 clear_buffer_uptodate(bh);
137 }
138 unlock_buffer(bh);
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700139}
140
141/*
142 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
143 * unlock the buffer. This is what ll_rw_block uses too.
144 */
145void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
146{
147 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148 put_bh(bh);
149}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700150EXPORT_SYMBOL(end_buffer_read_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700151
152void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
153{
154 char b[BDEVNAME_SIZE];
155
156 if (uptodate) {
157 set_buffer_uptodate(bh);
158 } else {
Keith Mannthey08bafc02008-11-25 10:24:35 +0100159 if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 buffer_io_error(bh);
161 printk(KERN_WARNING "lost page write due to "
162 "I/O error on %s\n",
163 bdevname(bh->b_bdev, b));
164 }
165 set_buffer_write_io_error(bh);
166 clear_buffer_uptodate(bh);
167 }
168 unlock_buffer(bh);
169 put_bh(bh);
170}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700171EXPORT_SYMBOL(end_buffer_write_sync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172
173/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 * Various filesystems appear to want __find_get_block to be non-blocking.
175 * But it's the page lock which protects the buffers. To get around this,
176 * we get exclusion from try_to_free_buffers with the blockdev mapping's
177 * private_lock.
178 *
179 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
180 * may be quite high. This code could TryLock the page, and if that
181 * succeeds, there is no need to take private_lock. (But if
182 * private_lock is contended then so is mapping->tree_lock).
183 */
184static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800185__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186{
187 struct inode *bd_inode = bdev->bd_inode;
188 struct address_space *bd_mapping = bd_inode->i_mapping;
189 struct buffer_head *ret = NULL;
190 pgoff_t index;
191 struct buffer_head *bh;
192 struct buffer_head *head;
193 struct page *page;
194 int all_mapped = 1;
195
196 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
197 page = find_get_page(bd_mapping, index);
198 if (!page)
199 goto out;
200
201 spin_lock(&bd_mapping->private_lock);
202 if (!page_has_buffers(page))
203 goto out_unlock;
204 head = page_buffers(page);
205 bh = head;
206 do {
Nikanth Karthikesan97f76d32009-04-02 16:56:46 -0700207 if (!buffer_mapped(bh))
208 all_mapped = 0;
209 else if (bh->b_blocknr == block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 ret = bh;
211 get_bh(bh);
212 goto out_unlock;
213 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 bh = bh->b_this_page;
215 } while (bh != head);
216
217 /* we might be here because some of the buffers on this page are
218 * not mapped. This is due to various races between
219 * file io on the block device and getblk. It gets dealt with
220 * elsewhere, don't buffer_error if we had some unmapped buffers
221 */
222 if (all_mapped) {
223 printk("__find_get_block_slow() failed. "
224 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800225 (unsigned long long)block,
226 (unsigned long long)bh->b_blocknr);
227 printk("b_state=0x%08lx, b_size=%zu\n",
228 bh->b_state, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
230 }
231out_unlock:
232 spin_unlock(&bd_mapping->private_lock);
233 page_cache_release(page);
234out:
235 return ret;
236}
237
238/* If invalidate_buffers() will trash dirty buffers, it means some kind
239 of fs corruption is going on. Trashing dirty data always imply losing
240 information that was supposed to be just stored on the physical layer
241 by the user.
242
243 Thus invalidate_buffers in general usage is not allwowed to trash
244 dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
245 be preserved. These buffers are simply skipped.
246
247 We also skip buffers which are still in use. For example this can
248 happen if a userspace program is reading the block device.
249
250 NOTE: In the case where the user removed a removable-media-disk even if
251 there's still dirty data not synced on disk (due a bug in the device driver
252 or due an error of the user), by not destroying the dirty buffers we could
253 generate corruption also on the next media inserted, thus a parameter is
254 necessary to handle this case in the most safe way possible (trying
255 to not corrupt also the new disk inserted with the data belonging to
256 the old now corrupted disk). Also for the ramdisk the natural thing
257 to do in order to release the ramdisk memory is to destroy dirty buffers.
258
259 These are two special cases. Normal usage imply the device driver
260 to issue a sync on the device (without waiting I/O completion) and
261 then an invalidate_buffers call that doesn't trash dirty buffers.
262
263 For handling cache coherency with the blkdev pagecache the 'update' case
264 is been introduced. It is needed to re-read from disk any pinned
265 buffer. NOTE: re-reading from disk is destructive so we can do it only
266 when we assume nobody is changing the buffercache under our I/O and when
267 we think the disk contains more recent information than the buffercache.
268 The update == 1 pass marks the buffers we need to update, the update == 2
269 pass does the actual I/O. */
Peter Zijlstraf98393a2007-05-06 14:49:54 -0700270void invalidate_bdev(struct block_device *bdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271{
Andrew Morton0e1dfc62006-07-30 03:03:28 -0700272 struct address_space *mapping = bdev->bd_inode->i_mapping;
273
274 if (mapping->nrpages == 0)
275 return;
276
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 invalidate_bh_lrus();
Tejun Heofa4b9072010-05-15 20:09:27 +0200278 lru_add_drain_all(); /* make sure all lru add caches are flushed */
Andrew Mortonfc0ecff2007-02-10 01:45:39 -0800279 invalidate_mapping_pages(mapping, 0, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700281EXPORT_SYMBOL(invalidate_bdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282
283/*
Jens Axboe5b0830c2009-09-23 19:37:09 +0200284 * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 */
286static void free_more_memory(void)
287{
Mel Gorman19770b32008-04-28 02:12:18 -0700288 struct zone *zone;
Mel Gorman0e884602008-04-28 02:12:14 -0700289 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290
Jens Axboe03ba3782009-09-09 09:08:54 +0200291 wakeup_flusher_threads(1024);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 yield();
293
Mel Gorman0e884602008-04-28 02:12:14 -0700294 for_each_online_node(nid) {
Mel Gorman19770b32008-04-28 02:12:18 -0700295 (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
296 gfp_zone(GFP_NOFS), NULL,
297 &zone);
298 if (zone)
Mel Gorman54a6eb52008-04-28 02:12:16 -0700299 try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700300 GFP_NOFS, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 }
302}
303
304/*
305 * I/O completion handler for block_read_full_page() - pages
306 * which come unlocked at the end of I/O.
307 */
308static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
309{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700311 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 struct buffer_head *tmp;
313 struct page *page;
314 int page_uptodate = 1;
315
316 BUG_ON(!buffer_async_read(bh));
317
318 page = bh->b_page;
319 if (uptodate) {
320 set_buffer_uptodate(bh);
321 } else {
322 clear_buffer_uptodate(bh);
Keith Mannthey08bafc02008-11-25 10:24:35 +0100323 if (!quiet_error(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324 buffer_io_error(bh);
325 SetPageError(page);
326 }
327
328 /*
329 * Be _very_ careful from here on. Bad things can happen if
330 * two buffer heads end IO at almost the same time and both
331 * decide that the page is now completely done.
332 */
Nick Piggina3972202005-07-07 17:56:56 -0700333 first = page_buffers(page);
334 local_irq_save(flags);
335 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 clear_buffer_async_read(bh);
337 unlock_buffer(bh);
338 tmp = bh;
339 do {
340 if (!buffer_uptodate(tmp))
341 page_uptodate = 0;
342 if (buffer_async_read(tmp)) {
343 BUG_ON(!buffer_locked(tmp));
344 goto still_busy;
345 }
346 tmp = tmp->b_this_page;
347 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700348 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
349 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350
351 /*
352 * If none of the buffers had errors and they are all
353 * uptodate then we can set the page uptodate.
354 */
355 if (page_uptodate && !PageError(page))
356 SetPageUptodate(page);
357 unlock_page(page);
358 return;
359
360still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700361 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
362 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 return;
364}
365
366/*
367 * Completion handler for block_write_full_page() - pages which are unlocked
368 * during I/O, and which have PageWriteback cleared upon I/O completion.
369 */
Chris Mason35c80d52009-04-15 13:22:38 -0400370void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371{
372 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700374 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375 struct buffer_head *tmp;
376 struct page *page;
377
378 BUG_ON(!buffer_async_write(bh));
379
380 page = bh->b_page;
381 if (uptodate) {
382 set_buffer_uptodate(bh);
383 } else {
Keith Mannthey08bafc02008-11-25 10:24:35 +0100384 if (!quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 buffer_io_error(bh);
386 printk(KERN_WARNING "lost page write due to "
387 "I/O error on %s\n",
388 bdevname(bh->b_bdev, b));
389 }
390 set_bit(AS_EIO, &page->mapping->flags);
Jan Kara58ff4072006-10-17 00:10:19 -0700391 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 clear_buffer_uptodate(bh);
393 SetPageError(page);
394 }
395
Nick Piggina3972202005-07-07 17:56:56 -0700396 first = page_buffers(page);
397 local_irq_save(flags);
398 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
399
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 clear_buffer_async_write(bh);
401 unlock_buffer(bh);
402 tmp = bh->b_this_page;
403 while (tmp != bh) {
404 if (buffer_async_write(tmp)) {
405 BUG_ON(!buffer_locked(tmp));
406 goto still_busy;
407 }
408 tmp = tmp->b_this_page;
409 }
Nick Piggina3972202005-07-07 17:56:56 -0700410 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
411 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 end_page_writeback(page);
413 return;
414
415still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700416 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
417 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 return;
419}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700420EXPORT_SYMBOL(end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421
422/*
423 * If a page's buffers are under async readin (end_buffer_async_read
424 * completion) then there is a possibility that another thread of
425 * control could lock one of the buffers after it has completed
426 * but while some of the other buffers have not completed. This
427 * locked buffer would confuse end_buffer_async_read() into not unlocking
428 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
429 * that this buffer is not under async I/O.
430 *
431 * The page comes unlocked when it has no locked buffer_async buffers
432 * left.
433 *
434 * PageLocked prevents anyone starting new async I/O reads any of
435 * the buffers.
436 *
437 * PageWriteback is used to prevent simultaneous writeout of the same
438 * page.
439 *
440 * PageLocked prevents anyone from starting writeback of a page which is
441 * under read I/O (PageWriteback is only ever set against a locked page).
442 */
443static void mark_buffer_async_read(struct buffer_head *bh)
444{
445 bh->b_end_io = end_buffer_async_read;
446 set_buffer_async_read(bh);
447}
448
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700449static void mark_buffer_async_write_endio(struct buffer_head *bh,
450 bh_end_io_t *handler)
Chris Mason35c80d52009-04-15 13:22:38 -0400451{
452 bh->b_end_io = handler;
453 set_buffer_async_write(bh);
454}
455
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456void mark_buffer_async_write(struct buffer_head *bh)
457{
Chris Mason35c80d52009-04-15 13:22:38 -0400458 mark_buffer_async_write_endio(bh, end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459}
460EXPORT_SYMBOL(mark_buffer_async_write);
461
462
463/*
464 * fs/buffer.c contains helper functions for buffer-backed address space's
465 * fsync functions. A common requirement for buffer-based filesystems is
466 * that certain data from the backing blockdev needs to be written out for
467 * a successful fsync(). For example, ext2 indirect blocks need to be
468 * written back and waited upon before fsync() returns.
469 *
470 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
471 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
472 * management of a list of dependent buffers at ->i_mapping->private_list.
473 *
474 * Locking is a little subtle: try_to_free_buffers() will remove buffers
475 * from their controlling inode's queue when they are being freed. But
476 * try_to_free_buffers() will be operating against the *blockdev* mapping
477 * at the time, not against the S_ISREG file which depends on those buffers.
478 * So the locking for private_list is via the private_lock in the address_space
479 * which backs the buffers. Which is different from the address_space
480 * against which the buffers are listed. So for a particular address_space,
481 * mapping->private_lock does *not* protect mapping->private_list! In fact,
482 * mapping->private_list will always be protected by the backing blockdev's
483 * ->private_lock.
484 *
485 * Which introduces a requirement: all buffers on an address_space's
486 * ->private_list must be from the same address_space: the blockdev's.
487 *
488 * address_spaces which do not place buffers at ->private_list via these
489 * utility functions are free to use private_lock and private_list for
490 * whatever they want. The only requirement is that list_empty(private_list)
491 * be true at clear_inode() time.
492 *
493 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
494 * filesystems should do that. invalidate_inode_buffers() should just go
495 * BUG_ON(!list_empty).
496 *
497 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
498 * take an address_space, not an inode. And it should be called
499 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
500 * queued up.
501 *
502 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
503 * list if it is already on a list. Because if the buffer is on a list,
504 * it *must* already be on the right one. If not, the filesystem is being
505 * silly. This will save a ton of locking. But first we have to ensure
506 * that buffers are taken *off* the old inode's list when they are freed
507 * (presumably in truncate). That requires careful auditing of all
508 * filesystems (do it inside bforget()). It could also be done by bringing
509 * b_inode back.
510 */
511
512/*
513 * The buffer's backing address_space's private_lock must be held
514 */
Thomas Petazzonidbacefc2008-07-29 22:33:47 -0700515static void __remove_assoc_queue(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516{
517 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -0700518 WARN_ON(!bh->b_assoc_map);
519 if (buffer_write_io_error(bh))
520 set_bit(AS_EIO, &bh->b_assoc_map->flags);
521 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700522}
523
524int inode_has_buffers(struct inode *inode)
525{
526 return !list_empty(&inode->i_data.private_list);
527}
528
529/*
530 * osync is designed to support O_SYNC io. It waits synchronously for
531 * all already-submitted IO to complete, but does not queue any new
532 * writes to the disk.
533 *
534 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
535 * you dirty the buffers, and then use osync_inode_buffers to wait for
536 * completion. Any other dirty buffers which are not yet queued for
537 * write will not be flushed to disk by the osync.
538 */
539static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
540{
541 struct buffer_head *bh;
542 struct list_head *p;
543 int err = 0;
544
545 spin_lock(lock);
546repeat:
547 list_for_each_prev(p, list) {
548 bh = BH_ENTRY(p);
549 if (buffer_locked(bh)) {
550 get_bh(bh);
551 spin_unlock(lock);
552 wait_on_buffer(bh);
553 if (!buffer_uptodate(bh))
554 err = -EIO;
555 brelse(bh);
556 spin_lock(lock);
557 goto repeat;
558 }
559 }
560 spin_unlock(lock);
561 return err;
562}
563
Al Viro01a05b32010-03-23 06:06:58 -0400564static void do_thaw_one(struct super_block *sb, void *unused)
565{
566 char b[BDEVNAME_SIZE];
567 while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
568 printk(KERN_WARNING "Emergency Thaw on %s\n",
569 bdevname(sb->s_bdev, b));
570}
571
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -0700572static void do_thaw_all(struct work_struct *work)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700573{
Al Viro01a05b32010-03-23 06:06:58 -0400574 iterate_supers(do_thaw_one, NULL);
Jens Axboe053c5252009-04-08 13:44:08 +0200575 kfree(work);
Eric Sandeenc2d75432009-03-31 15:23:46 -0700576 printk(KERN_WARNING "Emergency Thaw complete\n");
577}
578
579/**
580 * emergency_thaw_all -- forcibly thaw every frozen filesystem
581 *
582 * Used for emergency unfreeze of all filesystems via SysRq
583 */
584void emergency_thaw_all(void)
585{
Jens Axboe053c5252009-04-08 13:44:08 +0200586 struct work_struct *work;
587
588 work = kmalloc(sizeof(*work), GFP_ATOMIC);
589 if (work) {
590 INIT_WORK(work, do_thaw_all);
591 schedule_work(work);
592 }
Eric Sandeenc2d75432009-03-31 15:23:46 -0700593}
594
Linus Torvalds1da177e2005-04-16 15:20:36 -0700595/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800596 * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700597 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 *
599 * Starts I/O against the buffers at mapping->private_list, and waits upon
600 * that I/O.
601 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700602 * Basically, this is a convenience function for fsync().
603 * @mapping is a file or directory which needs those buffers to be written for
604 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 */
606int sync_mapping_buffers(struct address_space *mapping)
607{
608 struct address_space *buffer_mapping = mapping->assoc_mapping;
609
610 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
611 return 0;
612
613 return fsync_buffers_list(&buffer_mapping->private_lock,
614 &mapping->private_list);
615}
616EXPORT_SYMBOL(sync_mapping_buffers);
617
618/*
619 * Called when we've recently written block `bblock', and it is known that
620 * `bblock' was for a buffer_boundary() buffer. This means that the block at
621 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
622 * dirty, schedule it for IO. So that indirects merge nicely with their data.
623 */
624void write_boundary_block(struct block_device *bdev,
625 sector_t bblock, unsigned blocksize)
626{
627 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
628 if (bh) {
629 if (buffer_dirty(bh))
630 ll_rw_block(WRITE, 1, &bh);
631 put_bh(bh);
632 }
633}
634
635void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
636{
637 struct address_space *mapping = inode->i_mapping;
638 struct address_space *buffer_mapping = bh->b_page->mapping;
639
640 mark_buffer_dirty(bh);
641 if (!mapping->assoc_mapping) {
642 mapping->assoc_mapping = buffer_mapping;
643 } else {
Eric Sesterhenne827f922006-03-26 18:24:46 +0200644 BUG_ON(mapping->assoc_mapping != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 }
Jan Kara535ee2f2008-02-08 04:21:59 -0800646 if (!bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 spin_lock(&buffer_mapping->private_lock);
648 list_move_tail(&bh->b_assoc_buffers,
649 &mapping->private_list);
Jan Kara58ff4072006-10-17 00:10:19 -0700650 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 spin_unlock(&buffer_mapping->private_lock);
652 }
653}
654EXPORT_SYMBOL(mark_buffer_dirty_inode);
655
656/*
Nick Piggin787d2212007-07-17 04:03:34 -0700657 * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
658 * dirty.
659 *
660 * If warn is true, then emit a warning if the page is not uptodate and has
661 * not been truncated.
662 */
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700663static void __set_page_dirty(struct page *page,
Nick Piggin787d2212007-07-17 04:03:34 -0700664 struct address_space *mapping, int warn)
665{
Nick Piggin19fd6232008-07-25 19:45:32 -0700666 spin_lock_irq(&mapping->tree_lock);
Nick Piggin787d2212007-07-17 04:03:34 -0700667 if (page->mapping) { /* Race with truncate? */
668 WARN_ON_ONCE(warn && !PageUptodate(page));
Edward Shishkine3a7cca2009-03-31 15:19:39 -0700669 account_page_dirtied(page, mapping);
Nick Piggin787d2212007-07-17 04:03:34 -0700670 radix_tree_tag_set(&mapping->page_tree,
671 page_index(page), PAGECACHE_TAG_DIRTY);
672 }
Nick Piggin19fd6232008-07-25 19:45:32 -0700673 spin_unlock_irq(&mapping->tree_lock);
Nick Piggin787d2212007-07-17 04:03:34 -0700674 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Nick Piggin787d2212007-07-17 04:03:34 -0700675}
676
677/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678 * Add a page to the dirty page list.
679 *
680 * It is a sad fact of life that this function is called from several places
681 * deeply under spinlocking. It may not sleep.
682 *
683 * If the page has buffers, the uptodate buffers are set dirty, to preserve
684 * dirty-state coherency between the page and the buffers. It the page does
685 * not have buffers then when they are later attached they will all be set
686 * dirty.
687 *
688 * The buffers are dirtied before the page is dirtied. There's a small race
689 * window in which a writepage caller may see the page cleanness but not the
690 * buffer dirtiness. That's fine. If this code were to set the page dirty
691 * before the buffers, a concurrent writepage caller could clear the page dirty
692 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
693 * page on the dirty page list.
694 *
695 * We use private_lock to lock against try_to_free_buffers while using the
696 * page's buffer list. Also use this to protect against clean buffers being
697 * added to the page after it was set dirty.
698 *
699 * FIXME: may need to call ->reservepage here as well. That's rather up to the
700 * address_space though.
701 */
702int __set_page_dirty_buffers(struct page *page)
703{
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700704 int newly_dirty;
Nick Piggin787d2212007-07-17 04:03:34 -0700705 struct address_space *mapping = page_mapping(page);
Nick Pigginebf7a222006-10-10 04:36:54 +0200706
707 if (unlikely(!mapping))
708 return !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709
710 spin_lock(&mapping->private_lock);
711 if (page_has_buffers(page)) {
712 struct buffer_head *head = page_buffers(page);
713 struct buffer_head *bh = head;
714
715 do {
716 set_buffer_dirty(bh);
717 bh = bh->b_this_page;
718 } while (bh != head);
719 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700720 newly_dirty = !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 spin_unlock(&mapping->private_lock);
722
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700723 if (newly_dirty)
724 __set_page_dirty(page, mapping, 1);
725 return newly_dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726}
727EXPORT_SYMBOL(__set_page_dirty_buffers);
728
729/*
730 * Write out and wait upon a list of buffers.
731 *
732 * We have conflicting pressures: we want to make sure that all
733 * initially dirty buffers get waited on, but that any subsequently
734 * dirtied buffers don't. After all, we don't want fsync to last
735 * forever if somebody is actively writing to the file.
736 *
737 * Do this in two main stages: first we copy dirty buffers to a
738 * temporary inode list, queueing the writes as we go. Then we clean
739 * up, waiting for those writes to complete.
740 *
741 * During this second stage, any subsequent updates to the file may end
742 * up refiling the buffer on the original inode's dirty list again, so
743 * there is a chance we will end up with a buffer queued for write but
744 * not yet completed on that list. So, as a final cleanup we go through
745 * the osync code to catch these locked, dirty buffers without requeuing
746 * any newly dirty buffers for write.
747 */
748static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
749{
750 struct buffer_head *bh;
751 struct list_head tmp;
Jens Axboe9cf6b722009-04-06 14:48:03 +0200752 struct address_space *mapping, *prev_mapping = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 int err = 0, err2;
754
755 INIT_LIST_HEAD(&tmp);
756
757 spin_lock(lock);
758 while (!list_empty(list)) {
759 bh = BH_ENTRY(list->next);
Jan Kara535ee2f2008-02-08 04:21:59 -0800760 mapping = bh->b_assoc_map;
Jan Kara58ff4072006-10-17 00:10:19 -0700761 __remove_assoc_queue(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800762 /* Avoid race with mark_buffer_dirty_inode() which does
763 * a lockless check and we rely on seeing the dirty bit */
764 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 if (buffer_dirty(bh) || buffer_locked(bh)) {
766 list_add(&bh->b_assoc_buffers, &tmp);
Jan Kara535ee2f2008-02-08 04:21:59 -0800767 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 if (buffer_dirty(bh)) {
769 get_bh(bh);
770 spin_unlock(lock);
771 /*
772 * Ensure any pending I/O completes so that
773 * ll_rw_block() actually writes the current
774 * contents - it is a noop if I/O is still in
775 * flight on potentially older contents.
776 */
Jens Axboe9cf6b722009-04-06 14:48:03 +0200777 ll_rw_block(SWRITE_SYNC_PLUG, 1, &bh);
778
779 /*
780 * Kick off IO for the previous mapping. Note
781 * that we will not run the very last mapping,
782 * wait_on_buffer() will do that for us
783 * through sync_buffer().
784 */
785 if (prev_mapping && prev_mapping != mapping)
786 blk_run_address_space(prev_mapping);
787 prev_mapping = mapping;
788
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 brelse(bh);
790 spin_lock(lock);
791 }
792 }
793 }
794
795 while (!list_empty(&tmp)) {
796 bh = BH_ENTRY(tmp.prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 get_bh(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800798 mapping = bh->b_assoc_map;
799 __remove_assoc_queue(bh);
800 /* Avoid race with mark_buffer_dirty_inode() which does
801 * a lockless check and we rely on seeing the dirty bit */
802 smp_mb();
803 if (buffer_dirty(bh)) {
804 list_add(&bh->b_assoc_buffers,
Jan Karae3892292008-03-04 14:28:33 -0800805 &mapping->private_list);
Jan Kara535ee2f2008-02-08 04:21:59 -0800806 bh->b_assoc_map = mapping;
807 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 spin_unlock(lock);
809 wait_on_buffer(bh);
810 if (!buffer_uptodate(bh))
811 err = -EIO;
812 brelse(bh);
813 spin_lock(lock);
814 }
815
816 spin_unlock(lock);
817 err2 = osync_buffers_list(lock, list);
818 if (err)
819 return err;
820 else
821 return err2;
822}
823
824/*
825 * Invalidate any and all dirty buffers on a given inode. We are
826 * probably unmounting the fs, but that doesn't mean we have already
827 * done a sync(). Just drop the buffers from the inode list.
828 *
829 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
830 * assumes that all the buffers are against the blockdev. Not true
831 * for reiserfs.
832 */
833void invalidate_inode_buffers(struct inode *inode)
834{
835 if (inode_has_buffers(inode)) {
836 struct address_space *mapping = &inode->i_data;
837 struct list_head *list = &mapping->private_list;
838 struct address_space *buffer_mapping = mapping->assoc_mapping;
839
840 spin_lock(&buffer_mapping->private_lock);
841 while (!list_empty(list))
842 __remove_assoc_queue(BH_ENTRY(list->next));
843 spin_unlock(&buffer_mapping->private_lock);
844 }
845}
Jan Kara52b19ac2008-09-23 18:24:08 +0200846EXPORT_SYMBOL(invalidate_inode_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847
848/*
849 * Remove any clean buffers from the inode's buffer list. This is called
850 * when we're trying to free the inode itself. Those buffers can pin it.
851 *
852 * Returns true if all buffers were removed.
853 */
854int remove_inode_buffers(struct inode *inode)
855{
856 int ret = 1;
857
858 if (inode_has_buffers(inode)) {
859 struct address_space *mapping = &inode->i_data;
860 struct list_head *list = &mapping->private_list;
861 struct address_space *buffer_mapping = mapping->assoc_mapping;
862
863 spin_lock(&buffer_mapping->private_lock);
864 while (!list_empty(list)) {
865 struct buffer_head *bh = BH_ENTRY(list->next);
866 if (buffer_dirty(bh)) {
867 ret = 0;
868 break;
869 }
870 __remove_assoc_queue(bh);
871 }
872 spin_unlock(&buffer_mapping->private_lock);
873 }
874 return ret;
875}
876
877/*
878 * Create the appropriate buffers when given a page for data area and
879 * the size of each buffer.. Use the bh->b_this_page linked list to
880 * follow the buffers created. Return NULL if unable to create more
881 * buffers.
882 *
883 * The retry flag is used to differentiate async IO (paging, swapping)
884 * which may not fail from ordinary buffer allocations.
885 */
886struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
887 int retry)
888{
889 struct buffer_head *bh, *head;
890 long offset;
891
892try_again:
893 head = NULL;
894 offset = PAGE_SIZE;
895 while ((offset -= size) >= 0) {
896 bh = alloc_buffer_head(GFP_NOFS);
897 if (!bh)
898 goto no_grow;
899
900 bh->b_bdev = NULL;
901 bh->b_this_page = head;
902 bh->b_blocknr = -1;
903 head = bh;
904
905 bh->b_state = 0;
906 atomic_set(&bh->b_count, 0);
Chris Masonfc5cd582006-02-01 03:06:48 -0800907 bh->b_private = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 bh->b_size = size;
909
910 /* Link the buffer to its page */
911 set_bh_page(bh, page, offset);
912
Nathan Scott01ffe332006-01-17 09:02:07 +1100913 init_buffer(bh, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 }
915 return head;
916/*
917 * In case anything failed, we just free everything we got.
918 */
919no_grow:
920 if (head) {
921 do {
922 bh = head;
923 head = head->b_this_page;
924 free_buffer_head(bh);
925 } while (head);
926 }
927
928 /*
929 * Return failure for non-async IO requests. Async IO requests
930 * are not allowed to fail, so we have to wait until buffer heads
931 * become available. But we don't want tasks sleeping with
932 * partially complete buffers, so all were released above.
933 */
934 if (!retry)
935 return NULL;
936
937 /* We're _really_ low on memory. Now we just
938 * wait for old buffer heads to become free due to
939 * finishing IO. Since this is an async request and
940 * the reserve list is empty, we're sure there are
941 * async buffer heads in use.
942 */
943 free_more_memory();
944 goto try_again;
945}
946EXPORT_SYMBOL_GPL(alloc_page_buffers);
947
948static inline void
949link_dev_buffers(struct page *page, struct buffer_head *head)
950{
951 struct buffer_head *bh, *tail;
952
953 bh = head;
954 do {
955 tail = bh;
956 bh = bh->b_this_page;
957 } while (bh);
958 tail->b_this_page = head;
959 attach_page_buffers(page, head);
960}
961
962/*
963 * Initialise the state of a blockdev page's buffers.
964 */
965static void
966init_page_buffers(struct page *page, struct block_device *bdev,
967 sector_t block, int size)
968{
969 struct buffer_head *head = page_buffers(page);
970 struct buffer_head *bh = head;
971 int uptodate = PageUptodate(page);
972
973 do {
974 if (!buffer_mapped(bh)) {
975 init_buffer(bh, NULL, NULL);
976 bh->b_bdev = bdev;
977 bh->b_blocknr = block;
978 if (uptodate)
979 set_buffer_uptodate(bh);
980 set_buffer_mapped(bh);
981 }
982 block++;
983 bh = bh->b_this_page;
984 } while (bh != head);
985}
986
987/*
988 * Create the page-cache page that contains the requested block.
989 *
990 * This is user purely for blockdev mappings.
991 */
992static struct page *
993grow_dev_page(struct block_device *bdev, sector_t block,
994 pgoff_t index, int size)
995{
996 struct inode *inode = bdev->bd_inode;
997 struct page *page;
998 struct buffer_head *bh;
999
Christoph Lameterea125892007-05-16 22:11:21 -07001000 page = find_or_create_page(inode->i_mapping, index,
Mel Gorman769848c2007-07-17 04:03:05 -07001001 (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002 if (!page)
1003 return NULL;
1004
Eric Sesterhenne827f922006-03-26 18:24:46 +02001005 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006
1007 if (page_has_buffers(page)) {
1008 bh = page_buffers(page);
1009 if (bh->b_size == size) {
1010 init_page_buffers(page, bdev, block, size);
1011 return page;
1012 }
1013 if (!try_to_free_buffers(page))
1014 goto failed;
1015 }
1016
1017 /*
1018 * Allocate some buffers for this page
1019 */
1020 bh = alloc_page_buffers(page, size, 0);
1021 if (!bh)
1022 goto failed;
1023
1024 /*
1025 * Link the page to the buffers and initialise them. Take the
1026 * lock to be atomic wrt __find_get_block(), which does not
1027 * run under the page lock.
1028 */
1029 spin_lock(&inode->i_mapping->private_lock);
1030 link_dev_buffers(page, bh);
1031 init_page_buffers(page, bdev, block, size);
1032 spin_unlock(&inode->i_mapping->private_lock);
1033 return page;
1034
1035failed:
1036 BUG();
1037 unlock_page(page);
1038 page_cache_release(page);
1039 return NULL;
1040}
1041
1042/*
1043 * Create buffers for the specified block device block's page. If
1044 * that page was dirty, the buffers are set dirty also.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001045 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001046static int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001047grow_buffers(struct block_device *bdev, sector_t block, int size)
1048{
1049 struct page *page;
1050 pgoff_t index;
1051 int sizebits;
1052
1053 sizebits = -1;
1054 do {
1055 sizebits++;
1056 } while ((size << sizebits) < PAGE_SIZE);
1057
1058 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059
Andrew Mortone5657932006-10-11 01:21:46 -07001060 /*
1061 * Check for a block which wants to lie outside our maximum possible
1062 * pagecache index. (this comparison is done using sector_t types).
1063 */
1064 if (unlikely(index != block >> sizebits)) {
1065 char b[BDEVNAME_SIZE];
1066
1067 printk(KERN_ERR "%s: requested out-of-range block %llu for "
1068 "device %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07001069 __func__, (unsigned long long)block,
Andrew Mortone5657932006-10-11 01:21:46 -07001070 bdevname(bdev, b));
1071 return -EIO;
1072 }
1073 block = index << sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001074 /* Create a page with the proper size buffers.. */
1075 page = grow_dev_page(bdev, block, index, size);
1076 if (!page)
1077 return 0;
1078 unlock_page(page);
1079 page_cache_release(page);
1080 return 1;
1081}
1082
Adrian Bunk75c96f82005-05-05 16:16:09 -07001083static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001084__getblk_slow(struct block_device *bdev, sector_t block, int size)
1085{
1086 /* Size must be multiple of hard sectorsize */
Martin K. Petersene1defc42009-05-22 17:17:49 -04001087 if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088 (size < 512 || size > PAGE_SIZE))) {
1089 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1090 size);
Martin K. Petersene1defc42009-05-22 17:17:49 -04001091 printk(KERN_ERR "logical block size: %d\n",
1092 bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093
1094 dump_stack();
1095 return NULL;
1096 }
1097
1098 for (;;) {
1099 struct buffer_head * bh;
Andrew Mortone5657932006-10-11 01:21:46 -07001100 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001101
1102 bh = __find_get_block(bdev, block, size);
1103 if (bh)
1104 return bh;
1105
Andrew Mortone5657932006-10-11 01:21:46 -07001106 ret = grow_buffers(bdev, block, size);
1107 if (ret < 0)
1108 return NULL;
1109 if (ret == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 free_more_memory();
1111 }
1112}
1113
1114/*
1115 * The relationship between dirty buffers and dirty pages:
1116 *
1117 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1118 * the page is tagged dirty in its radix tree.
1119 *
1120 * At all times, the dirtiness of the buffers represents the dirtiness of
1121 * subsections of the page. If the page has buffers, the page dirty bit is
1122 * merely a hint about the true dirty state.
1123 *
1124 * When a page is set dirty in its entirety, all its buffers are marked dirty
1125 * (if the page has buffers).
1126 *
1127 * When a buffer is marked dirty, its page is dirtied, but the page's other
1128 * buffers are not.
1129 *
1130 * Also. When blockdev buffers are explicitly read with bread(), they
1131 * individually become uptodate. But their backing page remains not
1132 * uptodate - even if all of its buffers are uptodate. A subsequent
1133 * block_read_full_page() against that page will discover all the uptodate
1134 * buffers, will set the page uptodate and will perform no I/O.
1135 */
1136
1137/**
1138 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001139 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 *
1141 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1142 * backing page dirty, then tag the page as dirty in its address_space's radix
1143 * tree and then attach the address_space's inode to its superblock's dirty
1144 * inode list.
1145 *
1146 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
1147 * mapping->tree_lock and the global inode_lock.
1148 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001149void mark_buffer_dirty(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001150{
Nick Piggin787d2212007-07-17 04:03:34 -07001151 WARN_ON_ONCE(!buffer_uptodate(bh));
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001152
1153 /*
1154 * Very *carefully* optimize the it-is-already-dirty case.
1155 *
1156 * Don't let the final "is it dirty" escape to before we
1157 * perhaps modified the buffer.
1158 */
1159 if (buffer_dirty(bh)) {
1160 smp_mb();
1161 if (buffer_dirty(bh))
1162 return;
1163 }
1164
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001165 if (!test_set_buffer_dirty(bh)) {
1166 struct page *page = bh->b_page;
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001167 if (!TestSetPageDirty(page)) {
1168 struct address_space *mapping = page_mapping(page);
1169 if (mapping)
1170 __set_page_dirty(page, mapping, 0);
1171 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001172 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001174EXPORT_SYMBOL(mark_buffer_dirty);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175
1176/*
1177 * Decrement a buffer_head's reference count. If all buffers against a page
1178 * have zero reference count, are clean and unlocked, and if the page is clean
1179 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1180 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1181 * a page but it ends up not being freed, and buffers may later be reattached).
1182 */
1183void __brelse(struct buffer_head * buf)
1184{
1185 if (atomic_read(&buf->b_count)) {
1186 put_bh(buf);
1187 return;
1188 }
Arjan van de Ven5c752ad2008-07-25 19:45:40 -07001189 WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001191EXPORT_SYMBOL(__brelse);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001192
1193/*
1194 * bforget() is like brelse(), except it discards any
1195 * potentially dirty data.
1196 */
1197void __bforget(struct buffer_head *bh)
1198{
1199 clear_buffer_dirty(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -08001200 if (bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 struct address_space *buffer_mapping = bh->b_page->mapping;
1202
1203 spin_lock(&buffer_mapping->private_lock);
1204 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -07001205 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 spin_unlock(&buffer_mapping->private_lock);
1207 }
1208 __brelse(bh);
1209}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07001210EXPORT_SYMBOL(__bforget);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211
1212static struct buffer_head *__bread_slow(struct buffer_head *bh)
1213{
1214 lock_buffer(bh);
1215 if (buffer_uptodate(bh)) {
1216 unlock_buffer(bh);
1217 return bh;
1218 } else {
1219 get_bh(bh);
1220 bh->b_end_io = end_buffer_read_sync;
1221 submit_bh(READ, bh);
1222 wait_on_buffer(bh);
1223 if (buffer_uptodate(bh))
1224 return bh;
1225 }
1226 brelse(bh);
1227 return NULL;
1228}
1229
1230/*
1231 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1232 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1233 * refcount elevated by one when they're in an LRU. A buffer can only appear
1234 * once in a particular CPU's LRU. A single buffer can be present in multiple
1235 * CPU's LRUs at the same time.
1236 *
1237 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1238 * sb_find_get_block().
1239 *
1240 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1241 * a local interrupt disable for that.
1242 */
1243
1244#define BH_LRU_SIZE 8
1245
1246struct bh_lru {
1247 struct buffer_head *bhs[BH_LRU_SIZE];
1248};
1249
1250static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1251
1252#ifdef CONFIG_SMP
1253#define bh_lru_lock() local_irq_disable()
1254#define bh_lru_unlock() local_irq_enable()
1255#else
1256#define bh_lru_lock() preempt_disable()
1257#define bh_lru_unlock() preempt_enable()
1258#endif
1259
1260static inline void check_irqs_on(void)
1261{
1262#ifdef irqs_disabled
1263 BUG_ON(irqs_disabled());
1264#endif
1265}
1266
1267/*
1268 * The LRU management algorithm is dopey-but-simple. Sorry.
1269 */
1270static void bh_lru_install(struct buffer_head *bh)
1271{
1272 struct buffer_head *evictee = NULL;
1273 struct bh_lru *lru;
1274
1275 check_irqs_on();
1276 bh_lru_lock();
1277 lru = &__get_cpu_var(bh_lrus);
1278 if (lru->bhs[0] != bh) {
1279 struct buffer_head *bhs[BH_LRU_SIZE];
1280 int in;
1281 int out = 0;
1282
1283 get_bh(bh);
1284 bhs[out++] = bh;
1285 for (in = 0; in < BH_LRU_SIZE; in++) {
1286 struct buffer_head *bh2 = lru->bhs[in];
1287
1288 if (bh2 == bh) {
1289 __brelse(bh2);
1290 } else {
1291 if (out >= BH_LRU_SIZE) {
1292 BUG_ON(evictee != NULL);
1293 evictee = bh2;
1294 } else {
1295 bhs[out++] = bh2;
1296 }
1297 }
1298 }
1299 while (out < BH_LRU_SIZE)
1300 bhs[out++] = NULL;
1301 memcpy(lru->bhs, bhs, sizeof(bhs));
1302 }
1303 bh_lru_unlock();
1304
1305 if (evictee)
1306 __brelse(evictee);
1307}
1308
1309/*
1310 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1311 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001312static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001313lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314{
1315 struct buffer_head *ret = NULL;
1316 struct bh_lru *lru;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001317 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001318
1319 check_irqs_on();
1320 bh_lru_lock();
1321 lru = &__get_cpu_var(bh_lrus);
1322 for (i = 0; i < BH_LRU_SIZE; i++) {
1323 struct buffer_head *bh = lru->bhs[i];
1324
1325 if (bh && bh->b_bdev == bdev &&
1326 bh->b_blocknr == block && bh->b_size == size) {
1327 if (i) {
1328 while (i) {
1329 lru->bhs[i] = lru->bhs[i - 1];
1330 i--;
1331 }
1332 lru->bhs[0] = bh;
1333 }
1334 get_bh(bh);
1335 ret = bh;
1336 break;
1337 }
1338 }
1339 bh_lru_unlock();
1340 return ret;
1341}
1342
1343/*
1344 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1345 * it in the LRU and mark it as accessed. If it is not present then return
1346 * NULL
1347 */
1348struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001349__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350{
1351 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1352
1353 if (bh == NULL) {
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001354 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 if (bh)
1356 bh_lru_install(bh);
1357 }
1358 if (bh)
1359 touch_buffer(bh);
1360 return bh;
1361}
1362EXPORT_SYMBOL(__find_get_block);
1363
1364/*
1365 * __getblk will locate (and, if necessary, create) the buffer_head
1366 * which corresponds to the passed block_device, block and size. The
1367 * returned buffer has its reference count incremented.
1368 *
1369 * __getblk() cannot fail - it just keeps trying. If you pass it an
1370 * illegal block number, __getblk() will happily return a buffer_head
1371 * which represents the non-existent block. Very weird.
1372 *
1373 * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1374 * attempt is failing. FIXME, perhaps?
1375 */
1376struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001377__getblk(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378{
1379 struct buffer_head *bh = __find_get_block(bdev, block, size);
1380
1381 might_sleep();
1382 if (bh == NULL)
1383 bh = __getblk_slow(bdev, block, size);
1384 return bh;
1385}
1386EXPORT_SYMBOL(__getblk);
1387
1388/*
1389 * Do async read-ahead on a buffer..
1390 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001391void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001392{
1393 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001394 if (likely(bh)) {
1395 ll_rw_block(READA, 1, &bh);
1396 brelse(bh);
1397 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398}
1399EXPORT_SYMBOL(__breadahead);
1400
1401/**
1402 * __bread() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001403 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 * @block: number of block
1405 * @size: size (in bytes) to read
1406 *
1407 * Reads a specified block, and returns buffer head that contains it.
1408 * It returns NULL if the block was unreadable.
1409 */
1410struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001411__bread(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412{
1413 struct buffer_head *bh = __getblk(bdev, block, size);
1414
Andrew Mortona3e713b2005-10-30 15:03:15 -08001415 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416 bh = __bread_slow(bh);
1417 return bh;
1418}
1419EXPORT_SYMBOL(__bread);
1420
1421/*
1422 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1423 * This doesn't race because it runs in each cpu either in irq
1424 * or with preempt disabled.
1425 */
1426static void invalidate_bh_lru(void *arg)
1427{
1428 struct bh_lru *b = &get_cpu_var(bh_lrus);
1429 int i;
1430
1431 for (i = 0; i < BH_LRU_SIZE; i++) {
1432 brelse(b->bhs[i]);
1433 b->bhs[i] = NULL;
1434 }
1435 put_cpu_var(bh_lrus);
1436}
1437
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001438void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439{
Jens Axboe15c8b6c2008-05-09 09:39:44 +02001440 on_each_cpu(invalidate_bh_lru, NULL, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441}
Nick Piggin9db55792008-02-08 04:19:49 -08001442EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443
1444void set_bh_page(struct buffer_head *bh,
1445 struct page *page, unsigned long offset)
1446{
1447 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001448 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449 if (PageHighMem(page))
1450 /*
1451 * This catches illegal uses and preserves the offset:
1452 */
1453 bh->b_data = (char *)(0 + offset);
1454 else
1455 bh->b_data = page_address(page) + offset;
1456}
1457EXPORT_SYMBOL(set_bh_page);
1458
1459/*
1460 * Called when truncating a buffer on a page completely.
1461 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001462static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463{
1464 lock_buffer(bh);
1465 clear_buffer_dirty(bh);
1466 bh->b_bdev = NULL;
1467 clear_buffer_mapped(bh);
1468 clear_buffer_req(bh);
1469 clear_buffer_new(bh);
1470 clear_buffer_delay(bh);
David Chinner33a266d2007-02-12 00:51:41 -08001471 clear_buffer_unwritten(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 unlock_buffer(bh);
1473}
1474
1475/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476 * block_invalidatepage - invalidate part of all of a buffer-backed page
1477 *
1478 * @page: the page which is affected
1479 * @offset: the index of the truncation point
1480 *
1481 * block_invalidatepage() is called when all or part of the page has become
1482 * invalidatedby a truncate operation.
1483 *
1484 * block_invalidatepage() does not have to release all buffers, but it must
1485 * ensure that no dirty buffer is left outside @offset and that no I/O
1486 * is underway against any of the blocks which are outside the truncation
1487 * point. Because the caller is about to free (and possibly reuse) those
1488 * blocks on-disk.
1489 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001490void block_invalidatepage(struct page *page, unsigned long offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491{
1492 struct buffer_head *head, *bh, *next;
1493 unsigned int curr_off = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494
1495 BUG_ON(!PageLocked(page));
1496 if (!page_has_buffers(page))
1497 goto out;
1498
1499 head = page_buffers(page);
1500 bh = head;
1501 do {
1502 unsigned int next_off = curr_off + bh->b_size;
1503 next = bh->b_this_page;
1504
1505 /*
1506 * is this block fully invalidated?
1507 */
1508 if (offset <= curr_off)
1509 discard_buffer(bh);
1510 curr_off = next_off;
1511 bh = next;
1512 } while (bh != head);
1513
1514 /*
1515 * We release buffers only if the entire page is being invalidated.
1516 * The get_block cached value has been unconditionally invalidated,
1517 * so real IO is not possible anymore.
1518 */
1519 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001520 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001522 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523}
1524EXPORT_SYMBOL(block_invalidatepage);
1525
1526/*
1527 * We attach and possibly dirty the buffers atomically wrt
1528 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1529 * is already excluded via the page lock.
1530 */
1531void create_empty_buffers(struct page *page,
1532 unsigned long blocksize, unsigned long b_state)
1533{
1534 struct buffer_head *bh, *head, *tail;
1535
1536 head = alloc_page_buffers(page, blocksize, 1);
1537 bh = head;
1538 do {
1539 bh->b_state |= b_state;
1540 tail = bh;
1541 bh = bh->b_this_page;
1542 } while (bh);
1543 tail->b_this_page = head;
1544
1545 spin_lock(&page->mapping->private_lock);
1546 if (PageUptodate(page) || PageDirty(page)) {
1547 bh = head;
1548 do {
1549 if (PageDirty(page))
1550 set_buffer_dirty(bh);
1551 if (PageUptodate(page))
1552 set_buffer_uptodate(bh);
1553 bh = bh->b_this_page;
1554 } while (bh != head);
1555 }
1556 attach_page_buffers(page, head);
1557 spin_unlock(&page->mapping->private_lock);
1558}
1559EXPORT_SYMBOL(create_empty_buffers);
1560
1561/*
1562 * We are taking a block for data and we don't want any output from any
1563 * buffer-cache aliases starting from return from that function and
1564 * until the moment when something will explicitly mark the buffer
1565 * dirty (hopefully that will not happen until we will free that block ;-)
1566 * We don't even need to mark it not-uptodate - nobody can expect
1567 * anything from a newly allocated buffer anyway. We used to used
1568 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1569 * don't want to mark the alias unmapped, for example - it would confuse
1570 * anyone who might pick it with bread() afterwards...
1571 *
1572 * Also.. Note that bforget() doesn't lock the buffer. So there can
1573 * be writeout I/O going on against recently-freed buffers. We don't
1574 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1575 * only if we really need to. That happens here.
1576 */
1577void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1578{
1579 struct buffer_head *old_bh;
1580
1581 might_sleep();
1582
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001583 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 if (old_bh) {
1585 clear_buffer_dirty(old_bh);
1586 wait_on_buffer(old_bh);
1587 clear_buffer_req(old_bh);
1588 __brelse(old_bh);
1589 }
1590}
1591EXPORT_SYMBOL(unmap_underlying_metadata);
1592
1593/*
1594 * NOTE! All mapped/uptodate combinations are valid:
1595 *
1596 * Mapped Uptodate Meaning
1597 *
1598 * No No "unknown" - must do get_block()
1599 * No Yes "hole" - zero-filled
1600 * Yes No "allocated" - allocated on disk, not read in
1601 * Yes Yes "valid" - allocated and up-to-date in memory.
1602 *
1603 * "Dirty" is valid only with the last case (mapped+uptodate).
1604 */
1605
1606/*
1607 * While block_write_full_page is writing back the dirty buffers under
1608 * the page lock, whoever dirtied the buffers may decide to clean them
1609 * again at any time. We handle that by only looking at the buffer
1610 * state inside lock_buffer().
1611 *
1612 * If block_write_full_page() is called for regular writeback
1613 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1614 * locked buffer. This only can happen if someone has written the buffer
1615 * directly, with submit_bh(). At the address_space level PageWriteback
1616 * prevents this contention from occurring.
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001617 *
1618 * If block_write_full_page() is called with wbc->sync_mode ==
1619 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC_PLUG; this
1620 * causes the writes to be flagged as synchronous writes, but the
1621 * block device queue will NOT be unplugged, since usually many pages
1622 * will be pushed to the out before the higher-level caller actually
1623 * waits for the writes to be completed. The various wait functions,
1624 * such as wait_on_writeback_range() will ultimately call sync_page()
1625 * which will ultimately call blk_run_backing_dev(), which will end up
1626 * unplugging the device queue.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 */
1628static int __block_write_full_page(struct inode *inode, struct page *page,
Chris Mason35c80d52009-04-15 13:22:38 -04001629 get_block_t *get_block, struct writeback_control *wbc,
1630 bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631{
1632 int err;
1633 sector_t block;
1634 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001635 struct buffer_head *bh, *head;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001636 const unsigned blocksize = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637 int nr_underway = 0;
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001638 int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
1639 WRITE_SYNC_PLUG : WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001640
1641 BUG_ON(!PageLocked(page));
1642
1643 last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
1644
1645 if (!page_has_buffers(page)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001646 create_empty_buffers(page, blocksize,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 (1 << BH_Dirty)|(1 << BH_Uptodate));
1648 }
1649
1650 /*
1651 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1652 * here, and the (potentially unmapped) buffers may become dirty at
1653 * any time. If a buffer becomes dirty here after we've inspected it
1654 * then we just miss that fact, and the page stays dirty.
1655 *
1656 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1657 * handle that here by just cleaning them.
1658 */
1659
Andrew Morton54b21a72006-01-08 01:03:05 -08001660 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661 head = page_buffers(page);
1662 bh = head;
1663
1664 /*
1665 * Get all the dirty buffers mapped to disk addresses and
1666 * handle any aliases from the underlying blockdev's mapping.
1667 */
1668 do {
1669 if (block > last_block) {
1670 /*
1671 * mapped buffers outside i_size will occur, because
1672 * this page can be outside i_size when there is a
1673 * truncate in progress.
1674 */
1675 /*
1676 * The buffer was zeroed by block_write_full_page()
1677 */
1678 clear_buffer_dirty(bh);
1679 set_buffer_uptodate(bh);
Alex Tomas29a814d2008-07-11 19:27:31 -04001680 } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
1681 buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001682 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 err = get_block(inode, block, bh, 1);
1684 if (err)
1685 goto recover;
Alex Tomas29a814d2008-07-11 19:27:31 -04001686 clear_buffer_delay(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 if (buffer_new(bh)) {
1688 /* blockdev mappings never come here */
1689 clear_buffer_new(bh);
1690 unmap_underlying_metadata(bh->b_bdev,
1691 bh->b_blocknr);
1692 }
1693 }
1694 bh = bh->b_this_page;
1695 block++;
1696 } while (bh != head);
1697
1698 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 if (!buffer_mapped(bh))
1700 continue;
1701 /*
1702 * If it's a fully non-blocking write attempt and we cannot
1703 * lock the buffer then redirty the page. Note that this can
Jens Axboe5b0830c2009-09-23 19:37:09 +02001704 * potentially cause a busy-wait loop from writeback threads
1705 * and kswapd activity, but those code paths have their own
1706 * higher-level throttling.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 */
1708 if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
1709 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02001710 } else if (!trylock_buffer(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 redirty_page_for_writepage(wbc, page);
1712 continue;
1713 }
1714 if (test_clear_buffer_dirty(bh)) {
Chris Mason35c80d52009-04-15 13:22:38 -04001715 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001716 } else {
1717 unlock_buffer(bh);
1718 }
1719 } while ((bh = bh->b_this_page) != head);
1720
1721 /*
1722 * The page and its buffers are protected by PageWriteback(), so we can
1723 * drop the bh refcounts early.
1724 */
1725 BUG_ON(PageWriteback(page));
1726 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727
1728 do {
1729 struct buffer_head *next = bh->b_this_page;
1730 if (buffer_async_write(bh)) {
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001731 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 nr_underway++;
1733 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734 bh = next;
1735 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001736 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737
1738 err = 0;
1739done:
1740 if (nr_underway == 0) {
1741 /*
1742 * The page was marked dirty, but the buffers were
1743 * clean. Someone wrote them back by hand with
1744 * ll_rw_block/submit_bh. A rare case.
1745 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001747
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 /*
1749 * The page and buffer_heads can be released at any time from
1750 * here on.
1751 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752 }
1753 return err;
1754
1755recover:
1756 /*
1757 * ENOSPC, or some other error. We may already have added some
1758 * blocks to the file, so we need to write these out to avoid
1759 * exposing stale data.
1760 * The page is currently locked and not marked for writeback
1761 */
1762 bh = head;
1763 /* Recovery: lock and submit the mapped buffers */
1764 do {
Alex Tomas29a814d2008-07-11 19:27:31 -04001765 if (buffer_mapped(bh) && buffer_dirty(bh) &&
1766 !buffer_delay(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 lock_buffer(bh);
Chris Mason35c80d52009-04-15 13:22:38 -04001768 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769 } else {
1770 /*
1771 * The buffer may have been set dirty during
1772 * attachment to a dirty page.
1773 */
1774 clear_buffer_dirty(bh);
1775 }
1776 } while ((bh = bh->b_this_page) != head);
1777 SetPageError(page);
1778 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001779 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781 do {
1782 struct buffer_head *next = bh->b_this_page;
1783 if (buffer_async_write(bh)) {
1784 clear_buffer_dirty(bh);
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001785 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 nr_underway++;
1787 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788 bh = next;
1789 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001790 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 goto done;
1792}
1793
Nick Pigginafddba42007-10-16 01:25:01 -07001794/*
1795 * If a page has any new buffers, zero them out here, and mark them uptodate
1796 * and dirty so they'll be written out (in order to prevent uninitialised
1797 * block data from leaking). And clear the new bit.
1798 */
1799void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1800{
1801 unsigned int block_start, block_end;
1802 struct buffer_head *head, *bh;
1803
1804 BUG_ON(!PageLocked(page));
1805 if (!page_has_buffers(page))
1806 return;
1807
1808 bh = head = page_buffers(page);
1809 block_start = 0;
1810 do {
1811 block_end = block_start + bh->b_size;
1812
1813 if (buffer_new(bh)) {
1814 if (block_end > from && block_start < to) {
1815 if (!PageUptodate(page)) {
1816 unsigned start, size;
1817
1818 start = max(from, block_start);
1819 size = min(to, block_end) - start;
1820
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001821 zero_user(page, start, size);
Nick Pigginafddba42007-10-16 01:25:01 -07001822 set_buffer_uptodate(bh);
1823 }
1824
1825 clear_buffer_new(bh);
1826 mark_buffer_dirty(bh);
1827 }
1828 }
1829
1830 block_start = block_end;
1831 bh = bh->b_this_page;
1832 } while (bh != head);
1833}
1834EXPORT_SYMBOL(page_zero_new_buffers);
1835
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836static int __block_prepare_write(struct inode *inode, struct page *page,
1837 unsigned from, unsigned to, get_block_t *get_block)
1838{
1839 unsigned block_start, block_end;
1840 sector_t block;
1841 int err = 0;
1842 unsigned blocksize, bbits;
1843 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1844
1845 BUG_ON(!PageLocked(page));
1846 BUG_ON(from > PAGE_CACHE_SIZE);
1847 BUG_ON(to > PAGE_CACHE_SIZE);
1848 BUG_ON(from > to);
1849
1850 blocksize = 1 << inode->i_blkbits;
1851 if (!page_has_buffers(page))
1852 create_empty_buffers(page, blocksize, 0);
1853 head = page_buffers(page);
1854
1855 bbits = inode->i_blkbits;
1856 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1857
1858 for(bh = head, block_start = 0; bh != head || !block_start;
1859 block++, block_start=block_end, bh = bh->b_this_page) {
1860 block_end = block_start + blocksize;
1861 if (block_end <= from || block_start >= to) {
1862 if (PageUptodate(page)) {
1863 if (!buffer_uptodate(bh))
1864 set_buffer_uptodate(bh);
1865 }
1866 continue;
1867 }
1868 if (buffer_new(bh))
1869 clear_buffer_new(bh);
1870 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001871 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001872 err = get_block(inode, block, bh, 1);
1873 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001874 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 unmap_underlying_metadata(bh->b_bdev,
1877 bh->b_blocknr);
1878 if (PageUptodate(page)) {
Nick Piggin637aff42007-10-16 01:25:00 -07001879 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 set_buffer_uptodate(bh);
Nick Piggin637aff42007-10-16 01:25:00 -07001881 mark_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 continue;
1883 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001884 if (block_end > to || block_start < from)
1885 zero_user_segments(page,
1886 to, block_end,
1887 block_start, from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001888 continue;
1889 }
1890 }
1891 if (PageUptodate(page)) {
1892 if (!buffer_uptodate(bh))
1893 set_buffer_uptodate(bh);
1894 continue;
1895 }
1896 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08001897 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001898 (block_start < from || block_end > to)) {
1899 ll_rw_block(READ, 1, &bh);
1900 *wait_bh++=bh;
1901 }
1902 }
1903 /*
1904 * If we issued read requests - let them complete.
1905 */
1906 while(wait_bh > wait) {
1907 wait_on_buffer(*--wait_bh);
1908 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001909 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001910 }
Nick Pigginafddba42007-10-16 01:25:01 -07001911 if (unlikely(err))
1912 page_zero_new_buffers(page, from, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 return err;
1914}
1915
1916static int __block_commit_write(struct inode *inode, struct page *page,
1917 unsigned from, unsigned to)
1918{
1919 unsigned block_start, block_end;
1920 int partial = 0;
1921 unsigned blocksize;
1922 struct buffer_head *bh, *head;
1923
1924 blocksize = 1 << inode->i_blkbits;
1925
1926 for(bh = head = page_buffers(page), block_start = 0;
1927 bh != head || !block_start;
1928 block_start=block_end, bh = bh->b_this_page) {
1929 block_end = block_start + blocksize;
1930 if (block_end <= from || block_start >= to) {
1931 if (!buffer_uptodate(bh))
1932 partial = 1;
1933 } else {
1934 set_buffer_uptodate(bh);
1935 mark_buffer_dirty(bh);
1936 }
Nick Pigginafddba42007-10-16 01:25:01 -07001937 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 }
1939
1940 /*
1941 * If this is a partial write which happened to make all buffers
1942 * uptodate then we can optimize away a bogus readpage() for
1943 * the next read(). Here we 'discover' whether the page went
1944 * uptodate as a result of this (potentially partial) write.
1945 */
1946 if (!partial)
1947 SetPageUptodate(page);
1948 return 0;
1949}
1950
1951/*
Nick Pigginafddba42007-10-16 01:25:01 -07001952 * block_write_begin takes care of the basic task of block allocation and
1953 * bringing partial write blocks uptodate first.
1954 *
1955 * If *pagep is not NULL, then block_write_begin uses the locked page
1956 * at *pagep rather than allocating its own. In this case, the page will
1957 * not be unlocked or deallocated on failure.
1958 */
1959int block_write_begin(struct file *file, struct address_space *mapping,
1960 loff_t pos, unsigned len, unsigned flags,
1961 struct page **pagep, void **fsdata,
1962 get_block_t *get_block)
1963{
1964 struct inode *inode = mapping->host;
1965 int status = 0;
1966 struct page *page;
1967 pgoff_t index;
1968 unsigned start, end;
1969 int ownpage = 0;
1970
1971 index = pos >> PAGE_CACHE_SHIFT;
1972 start = pos & (PAGE_CACHE_SIZE - 1);
1973 end = start + len;
1974
1975 page = *pagep;
1976 if (page == NULL) {
1977 ownpage = 1;
Nick Piggin54566b22009-01-04 12:00:53 -08001978 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Pigginafddba42007-10-16 01:25:01 -07001979 if (!page) {
1980 status = -ENOMEM;
1981 goto out;
1982 }
1983 *pagep = page;
1984 } else
1985 BUG_ON(!PageLocked(page));
1986
1987 status = __block_prepare_write(inode, page, start, end, get_block);
1988 if (unlikely(status)) {
1989 ClearPageUptodate(page);
1990
1991 if (ownpage) {
1992 unlock_page(page);
1993 page_cache_release(page);
1994 *pagep = NULL;
1995
1996 /*
1997 * prepare_write() may have instantiated a few blocks
1998 * outside i_size. Trim these off again. Don't need
1999 * i_size_read because we hold i_mutex.
2000 */
2001 if (pos + len > inode->i_size)
2002 vmtruncate(inode, inode->i_size);
2003 }
Nick Pigginafddba42007-10-16 01:25:01 -07002004 }
2005
2006out:
2007 return status;
2008}
2009EXPORT_SYMBOL(block_write_begin);
2010
2011int block_write_end(struct file *file, struct address_space *mapping,
2012 loff_t pos, unsigned len, unsigned copied,
2013 struct page *page, void *fsdata)
2014{
2015 struct inode *inode = mapping->host;
2016 unsigned start;
2017
2018 start = pos & (PAGE_CACHE_SIZE - 1);
2019
2020 if (unlikely(copied < len)) {
2021 /*
2022 * The buffers that were written will now be uptodate, so we
2023 * don't have to worry about a readpage reading them and
2024 * overwriting a partial write. However if we have encountered
2025 * a short write and only partially written into a buffer, it
2026 * will not be marked uptodate, so a readpage might come in and
2027 * destroy our partial write.
2028 *
2029 * Do the simplest thing, and just treat any short write to a
2030 * non uptodate page as a zero-length write, and force the
2031 * caller to redo the whole thing.
2032 */
2033 if (!PageUptodate(page))
2034 copied = 0;
2035
2036 page_zero_new_buffers(page, start+copied, start+len);
2037 }
2038 flush_dcache_page(page);
2039
2040 /* This could be a short (even 0-length) commit */
2041 __block_commit_write(inode, page, start, start+copied);
2042
2043 return copied;
2044}
2045EXPORT_SYMBOL(block_write_end);
2046
2047int generic_write_end(struct file *file, struct address_space *mapping,
2048 loff_t pos, unsigned len, unsigned copied,
2049 struct page *page, void *fsdata)
2050{
2051 struct inode *inode = mapping->host;
Jan Karac7d206b2008-07-11 19:27:31 -04002052 int i_size_changed = 0;
Nick Pigginafddba42007-10-16 01:25:01 -07002053
2054 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2055
2056 /*
2057 * No need to use i_size_read() here, the i_size
2058 * cannot change under us because we hold i_mutex.
2059 *
2060 * But it's important to update i_size while still holding page lock:
2061 * page writeout could otherwise come in and zero beyond i_size.
2062 */
2063 if (pos+copied > inode->i_size) {
2064 i_size_write(inode, pos+copied);
Jan Karac7d206b2008-07-11 19:27:31 -04002065 i_size_changed = 1;
Nick Pigginafddba42007-10-16 01:25:01 -07002066 }
2067
2068 unlock_page(page);
2069 page_cache_release(page);
2070
Jan Karac7d206b2008-07-11 19:27:31 -04002071 /*
2072 * Don't mark the inode dirty under page lock. First, it unnecessarily
2073 * makes the holding time of page lock longer. Second, it forces lock
2074 * ordering of page lock and transaction start for journaling
2075 * filesystems.
2076 */
2077 if (i_size_changed)
2078 mark_inode_dirty(inode);
2079
Nick Pigginafddba42007-10-16 01:25:01 -07002080 return copied;
2081}
2082EXPORT_SYMBOL(generic_write_end);
2083
2084/*
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002085 * block_is_partially_uptodate checks whether buffers within a page are
2086 * uptodate or not.
2087 *
2088 * Returns true if all buffers which correspond to a file portion
2089 * we want to read are uptodate.
2090 */
2091int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
2092 unsigned long from)
2093{
2094 struct inode *inode = page->mapping->host;
2095 unsigned block_start, block_end, blocksize;
2096 unsigned to;
2097 struct buffer_head *bh, *head;
2098 int ret = 1;
2099
2100 if (!page_has_buffers(page))
2101 return 0;
2102
2103 blocksize = 1 << inode->i_blkbits;
2104 to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
2105 to = from + to;
2106 if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2107 return 0;
2108
2109 head = page_buffers(page);
2110 bh = head;
2111 block_start = 0;
2112 do {
2113 block_end = block_start + blocksize;
2114 if (block_end > from && block_start < to) {
2115 if (!buffer_uptodate(bh)) {
2116 ret = 0;
2117 break;
2118 }
2119 if (block_end >= to)
2120 break;
2121 }
2122 block_start = block_end;
2123 bh = bh->b_this_page;
2124 } while (bh != head);
2125
2126 return ret;
2127}
2128EXPORT_SYMBOL(block_is_partially_uptodate);
2129
2130/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131 * Generic "read page" function for block devices that have the normal
2132 * get_block functionality. This is most of the block device filesystems.
2133 * Reads the page asynchronously --- the unlock_buffer() and
2134 * set/clear_buffer_uptodate() functions propagate buffer state into the
2135 * page struct once IO has completed.
2136 */
2137int block_read_full_page(struct page *page, get_block_t *get_block)
2138{
2139 struct inode *inode = page->mapping->host;
2140 sector_t iblock, lblock;
2141 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
2142 unsigned int blocksize;
2143 int nr, i;
2144 int fully_mapped = 1;
2145
Matt Mackallcd7619d2005-05-01 08:59:01 -07002146 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147 blocksize = 1 << inode->i_blkbits;
2148 if (!page_has_buffers(page))
2149 create_empty_buffers(page, blocksize, 0);
2150 head = page_buffers(page);
2151
2152 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2153 lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
2154 bh = head;
2155 nr = 0;
2156 i = 0;
2157
2158 do {
2159 if (buffer_uptodate(bh))
2160 continue;
2161
2162 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002163 int err = 0;
2164
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 fully_mapped = 0;
2166 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002167 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002168 err = get_block(inode, iblock, bh, 0);
2169 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 SetPageError(page);
2171 }
2172 if (!buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002173 zero_user(page, i * blocksize, blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002174 if (!err)
2175 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002176 continue;
2177 }
2178 /*
2179 * get_block() might have updated the buffer
2180 * synchronously
2181 */
2182 if (buffer_uptodate(bh))
2183 continue;
2184 }
2185 arr[nr++] = bh;
2186 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2187
2188 if (fully_mapped)
2189 SetPageMappedToDisk(page);
2190
2191 if (!nr) {
2192 /*
2193 * All buffers are uptodate - we can set the page uptodate
2194 * as well. But not if get_block() returned an error.
2195 */
2196 if (!PageError(page))
2197 SetPageUptodate(page);
2198 unlock_page(page);
2199 return 0;
2200 }
2201
2202 /* Stage two: lock the buffers */
2203 for (i = 0; i < nr; i++) {
2204 bh = arr[i];
2205 lock_buffer(bh);
2206 mark_buffer_async_read(bh);
2207 }
2208
2209 /*
2210 * Stage 3: start the IO. Check for uptodateness
2211 * inside the buffer lock in case another process reading
2212 * the underlying blockdev brought it uptodate (the sct fix).
2213 */
2214 for (i = 0; i < nr; i++) {
2215 bh = arr[i];
2216 if (buffer_uptodate(bh))
2217 end_buffer_async_read(bh, 1);
2218 else
2219 submit_bh(READ, bh);
2220 }
2221 return 0;
2222}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002223EXPORT_SYMBOL(block_read_full_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224
2225/* utility function for filesystems that need to do work on expanding
Nick Piggin89e10782007-10-16 01:25:07 -07002226 * truncates. Uses filesystem pagecache writes to allow the filesystem to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227 * deal with the hole.
2228 */
Nick Piggin89e10782007-10-16 01:25:07 -07002229int generic_cont_expand_simple(struct inode *inode, loff_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002230{
2231 struct address_space *mapping = inode->i_mapping;
2232 struct page *page;
Nick Piggin89e10782007-10-16 01:25:07 -07002233 void *fsdata;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002234 int err;
2235
npiggin@suse.dec08d3b02009-08-21 02:35:06 +10002236 err = inode_newsize_ok(inode, size);
2237 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002238 goto out;
2239
Nick Piggin89e10782007-10-16 01:25:07 -07002240 err = pagecache_write_begin(NULL, mapping, size, 0,
2241 AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2242 &page, &fsdata);
2243 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002244 goto out;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002245
Nick Piggin89e10782007-10-16 01:25:07 -07002246 err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2247 BUG_ON(err > 0);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002248
Linus Torvalds1da177e2005-04-16 15:20:36 -07002249out:
2250 return err;
2251}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002252EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002253
Adrian Bunkf1e3af72008-04-29 00:59:01 -07002254static int cont_expand_zero(struct file *file, struct address_space *mapping,
2255 loff_t pos, loff_t *bytes)
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002256{
Nick Piggin89e10782007-10-16 01:25:07 -07002257 struct inode *inode = mapping->host;
2258 unsigned blocksize = 1 << inode->i_blkbits;
2259 struct page *page;
2260 void *fsdata;
2261 pgoff_t index, curidx;
2262 loff_t curpos;
2263 unsigned zerofrom, offset, len;
2264 int err = 0;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002265
Nick Piggin89e10782007-10-16 01:25:07 -07002266 index = pos >> PAGE_CACHE_SHIFT;
2267 offset = pos & ~PAGE_CACHE_MASK;
2268
2269 while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2270 zerofrom = curpos & ~PAGE_CACHE_MASK;
2271 if (zerofrom & (blocksize-1)) {
2272 *bytes |= (blocksize-1);
2273 (*bytes)++;
2274 }
2275 len = PAGE_CACHE_SIZE - zerofrom;
2276
2277 err = pagecache_write_begin(file, mapping, curpos, len,
2278 AOP_FLAG_UNINTERRUPTIBLE,
2279 &page, &fsdata);
2280 if (err)
2281 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002282 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002283 err = pagecache_write_end(file, mapping, curpos, len, len,
2284 page, fsdata);
2285 if (err < 0)
2286 goto out;
2287 BUG_ON(err != len);
2288 err = 0;
OGAWA Hirofumi061e9742008-04-28 02:16:28 -07002289
2290 balance_dirty_pages_ratelimited(mapping);
Nick Piggin89e10782007-10-16 01:25:07 -07002291 }
2292
2293 /* page covers the boundary, find the boundary offset */
2294 if (index == curidx) {
2295 zerofrom = curpos & ~PAGE_CACHE_MASK;
2296 /* if we will expand the thing last block will be filled */
2297 if (offset <= zerofrom) {
2298 goto out;
2299 }
2300 if (zerofrom & (blocksize-1)) {
2301 *bytes |= (blocksize-1);
2302 (*bytes)++;
2303 }
2304 len = offset - zerofrom;
2305
2306 err = pagecache_write_begin(file, mapping, curpos, len,
2307 AOP_FLAG_UNINTERRUPTIBLE,
2308 &page, &fsdata);
2309 if (err)
2310 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002311 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002312 err = pagecache_write_end(file, mapping, curpos, len, len,
2313 page, fsdata);
2314 if (err < 0)
2315 goto out;
2316 BUG_ON(err != len);
2317 err = 0;
2318 }
2319out:
2320 return err;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002321}
2322
Linus Torvalds1da177e2005-04-16 15:20:36 -07002323/*
2324 * For moronic filesystems that do not allow holes in file.
2325 * We may have to extend the file.
2326 */
Nick Piggin89e10782007-10-16 01:25:07 -07002327int cont_write_begin(struct file *file, struct address_space *mapping,
2328 loff_t pos, unsigned len, unsigned flags,
2329 struct page **pagep, void **fsdata,
2330 get_block_t *get_block, loff_t *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333 unsigned blocksize = 1 << inode->i_blkbits;
Nick Piggin89e10782007-10-16 01:25:07 -07002334 unsigned zerofrom;
2335 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336
Nick Piggin89e10782007-10-16 01:25:07 -07002337 err = cont_expand_zero(file, mapping, pos, bytes);
2338 if (err)
2339 goto out;
2340
2341 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2342 if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2343 *bytes |= (blocksize-1);
2344 (*bytes)++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345 }
2346
Nick Piggin89e10782007-10-16 01:25:07 -07002347 *pagep = NULL;
2348 err = block_write_begin(file, mapping, pos, len,
2349 flags, pagep, fsdata, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002350out:
Nick Piggin89e10782007-10-16 01:25:07 -07002351 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002353EXPORT_SYMBOL(cont_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354
2355int block_prepare_write(struct page *page, unsigned from, unsigned to,
2356 get_block_t *get_block)
2357{
2358 struct inode *inode = page->mapping->host;
2359 int err = __block_prepare_write(inode, page, from, to, get_block);
2360 if (err)
2361 ClearPageUptodate(page);
2362 return err;
2363}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002364EXPORT_SYMBOL(block_prepare_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365
2366int block_commit_write(struct page *page, unsigned from, unsigned to)
2367{
2368 struct inode *inode = page->mapping->host;
2369 __block_commit_write(inode,page,from,to);
2370 return 0;
2371}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002372EXPORT_SYMBOL(block_commit_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373
David Chinner54171692007-07-19 17:39:55 +10002374/*
2375 * block_page_mkwrite() is not allowed to change the file size as it gets
2376 * called from a page fault handler when a page is first dirtied. Hence we must
2377 * be careful to check for EOF conditions here. We set the page up correctly
2378 * for a written page which means we get ENOSPC checking when writing into
2379 * holes and correct delalloc and unwritten extent mapping on filesystems that
2380 * support these features.
2381 *
2382 * We are not allowed to take the i_mutex here so we have to play games to
2383 * protect against truncate races as the page could now be beyond EOF. Because
2384 * vmtruncate() writes the inode size before removing pages, once we have the
2385 * page lock we can determine safely if the page is beyond EOF. If it is not
2386 * beyond EOF, then the page is guaranteed safe against truncation until we
2387 * unlock the page.
2388 */
2389int
Nick Pigginc2ec1752009-03-31 15:23:21 -07002390block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
David Chinner54171692007-07-19 17:39:55 +10002391 get_block_t get_block)
2392{
Nick Pigginc2ec1752009-03-31 15:23:21 -07002393 struct page *page = vmf->page;
David Chinner54171692007-07-19 17:39:55 +10002394 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
2395 unsigned long end;
2396 loff_t size;
Nick Piggin56a76f82009-03-31 15:23:23 -07002397 int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
David Chinner54171692007-07-19 17:39:55 +10002398
2399 lock_page(page);
2400 size = i_size_read(inode);
2401 if ((page->mapping != inode->i_mapping) ||
Nick Piggin18336332007-07-20 00:31:45 -07002402 (page_offset(page) > size)) {
David Chinner54171692007-07-19 17:39:55 +10002403 /* page got truncated out from underneath us */
Nick Pigginb827e492009-04-30 15:08:16 -07002404 unlock_page(page);
2405 goto out;
David Chinner54171692007-07-19 17:39:55 +10002406 }
2407
2408 /* page is wholly or partially inside EOF */
2409 if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2410 end = size & ~PAGE_CACHE_MASK;
2411 else
2412 end = PAGE_CACHE_SIZE;
2413
2414 ret = block_prepare_write(page, 0, end, get_block);
2415 if (!ret)
2416 ret = block_commit_write(page, 0, end);
2417
Nick Piggin56a76f82009-03-31 15:23:23 -07002418 if (unlikely(ret)) {
Nick Pigginb827e492009-04-30 15:08:16 -07002419 unlock_page(page);
Nick Piggin56a76f82009-03-31 15:23:23 -07002420 if (ret == -ENOMEM)
2421 ret = VM_FAULT_OOM;
2422 else /* -ENOSPC, -EIO, etc */
2423 ret = VM_FAULT_SIGBUS;
Nick Pigginb827e492009-04-30 15:08:16 -07002424 } else
2425 ret = VM_FAULT_LOCKED;
Nick Pigginc2ec1752009-03-31 15:23:21 -07002426
Nick Pigginb827e492009-04-30 15:08:16 -07002427out:
David Chinner54171692007-07-19 17:39:55 +10002428 return ret;
2429}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002430EXPORT_SYMBOL(block_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002431
2432/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002433 * nobh_write_begin()'s prereads are special: the buffer_heads are freed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 * immediately, while under the page lock. So it needs a special end_io
2435 * handler which does not touch the bh after unlocking it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002436 */
2437static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2438{
Dmitry Monakhov68671f32007-10-16 01:24:47 -07002439 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440}
2441
2442/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002443 * Attach the singly-linked list of buffers created by nobh_write_begin, to
2444 * the page (converting it to circular linked list and taking care of page
2445 * dirty races).
2446 */
2447static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2448{
2449 struct buffer_head *bh;
2450
2451 BUG_ON(!PageLocked(page));
2452
2453 spin_lock(&page->mapping->private_lock);
2454 bh = head;
2455 do {
2456 if (PageDirty(page))
2457 set_buffer_dirty(bh);
2458 if (!bh->b_this_page)
2459 bh->b_this_page = head;
2460 bh = bh->b_this_page;
2461 } while (bh != head);
2462 attach_page_buffers(page, head);
2463 spin_unlock(&page->mapping->private_lock);
2464}
2465
2466/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002467 * On entry, the page is fully not uptodate.
2468 * On exit the page is fully uptodate in the areas outside (from,to)
2469 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002470int nobh_write_begin(struct file *file, struct address_space *mapping,
2471 loff_t pos, unsigned len, unsigned flags,
2472 struct page **pagep, void **fsdata,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473 get_block_t *get_block)
2474{
Nick Piggin03158cd2007-10-16 01:25:25 -07002475 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002476 const unsigned blkbits = inode->i_blkbits;
2477 const unsigned blocksize = 1 << blkbits;
Nick Piggina4b06722007-10-16 01:24:48 -07002478 struct buffer_head *head, *bh;
Nick Piggin03158cd2007-10-16 01:25:25 -07002479 struct page *page;
2480 pgoff_t index;
2481 unsigned from, to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002482 unsigned block_in_page;
Nick Piggina4b06722007-10-16 01:24:48 -07002483 unsigned block_start, block_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484 sector_t block_in_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002485 int nr_reads = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002486 int ret = 0;
2487 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002488
Nick Piggin03158cd2007-10-16 01:25:25 -07002489 index = pos >> PAGE_CACHE_SHIFT;
2490 from = pos & (PAGE_CACHE_SIZE - 1);
2491 to = from + len;
2492
Nick Piggin54566b22009-01-04 12:00:53 -08002493 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Piggin03158cd2007-10-16 01:25:25 -07002494 if (!page)
2495 return -ENOMEM;
2496 *pagep = page;
2497 *fsdata = NULL;
2498
2499 if (page_has_buffers(page)) {
2500 unlock_page(page);
2501 page_cache_release(page);
2502 *pagep = NULL;
2503 return block_write_begin(file, mapping, pos, len, flags, pagep,
2504 fsdata, get_block);
2505 }
Nick Piggina4b06722007-10-16 01:24:48 -07002506
Linus Torvalds1da177e2005-04-16 15:20:36 -07002507 if (PageMappedToDisk(page))
2508 return 0;
2509
Nick Piggina4b06722007-10-16 01:24:48 -07002510 /*
2511 * Allocate buffers so that we can keep track of state, and potentially
2512 * attach them to the page if an error occurs. In the common case of
2513 * no error, they will just be freed again without ever being attached
2514 * to the page (which is all OK, because we're under the page lock).
2515 *
2516 * Be careful: the buffer linked list is a NULL terminated one, rather
2517 * than the circular one we're used to.
2518 */
2519 head = alloc_page_buffers(page, blocksize, 0);
Nick Piggin03158cd2007-10-16 01:25:25 -07002520 if (!head) {
2521 ret = -ENOMEM;
2522 goto out_release;
2523 }
Nick Piggina4b06722007-10-16 01:24:48 -07002524
Linus Torvalds1da177e2005-04-16 15:20:36 -07002525 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002526
2527 /*
2528 * We loop across all blocks in the page, whether or not they are
2529 * part of the affected region. This is so we can discover if the
2530 * page is fully mapped-to-disk.
2531 */
Nick Piggina4b06722007-10-16 01:24:48 -07002532 for (block_start = 0, block_in_page = 0, bh = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533 block_start < PAGE_CACHE_SIZE;
Nick Piggina4b06722007-10-16 01:24:48 -07002534 block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002535 int create;
2536
Nick Piggina4b06722007-10-16 01:24:48 -07002537 block_end = block_start + blocksize;
2538 bh->b_state = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002539 create = 1;
2540 if (block_start >= to)
2541 create = 0;
2542 ret = get_block(inode, block_in_file + block_in_page,
Nick Piggina4b06722007-10-16 01:24:48 -07002543 bh, create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002544 if (ret)
2545 goto failed;
Nick Piggina4b06722007-10-16 01:24:48 -07002546 if (!buffer_mapped(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002547 is_mapped_to_disk = 0;
Nick Piggina4b06722007-10-16 01:24:48 -07002548 if (buffer_new(bh))
2549 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2550 if (PageUptodate(page)) {
2551 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552 continue;
Nick Piggina4b06722007-10-16 01:24:48 -07002553 }
2554 if (buffer_new(bh) || !buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002555 zero_user_segments(page, block_start, from,
2556 to, block_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002557 continue;
2558 }
Nick Piggina4b06722007-10-16 01:24:48 -07002559 if (buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002560 continue; /* reiserfs does this */
2561 if (block_start < from || block_end > to) {
Nick Piggina4b06722007-10-16 01:24:48 -07002562 lock_buffer(bh);
2563 bh->b_end_io = end_buffer_read_nobh;
2564 submit_bh(READ, bh);
2565 nr_reads++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002566 }
2567 }
2568
2569 if (nr_reads) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002570 /*
2571 * The page is locked, so these buffers are protected from
2572 * any VM or truncate activity. Hence we don't need to care
2573 * for the buffer_head refcounts.
2574 */
Nick Piggina4b06722007-10-16 01:24:48 -07002575 for (bh = head; bh; bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002576 wait_on_buffer(bh);
2577 if (!buffer_uptodate(bh))
2578 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579 }
2580 if (ret)
2581 goto failed;
2582 }
2583
2584 if (is_mapped_to_disk)
2585 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002586
Nick Piggin03158cd2007-10-16 01:25:25 -07002587 *fsdata = head; /* to be released by nobh_write_end */
Nick Piggina4b06722007-10-16 01:24:48 -07002588
Linus Torvalds1da177e2005-04-16 15:20:36 -07002589 return 0;
2590
2591failed:
Nick Piggin03158cd2007-10-16 01:25:25 -07002592 BUG_ON(!ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002593 /*
Nick Piggina4b06722007-10-16 01:24:48 -07002594 * Error recovery is a bit difficult. We need to zero out blocks that
2595 * were newly allocated, and dirty them to ensure they get written out.
2596 * Buffers need to be attached to the page at this point, otherwise
2597 * the handling of potential IO errors during writeout would be hard
2598 * (could try doing synchronous writeout, but what if that fails too?)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002600 attach_nobh_buffers(page, head);
2601 page_zero_new_buffers(page, from, to);
Nick Piggina4b06722007-10-16 01:24:48 -07002602
Nick Piggin03158cd2007-10-16 01:25:25 -07002603out_release:
2604 unlock_page(page);
2605 page_cache_release(page);
2606 *pagep = NULL;
Nick Piggina4b06722007-10-16 01:24:48 -07002607
Nick Piggin03158cd2007-10-16 01:25:25 -07002608 if (pos + len > inode->i_size)
2609 vmtruncate(inode, inode->i_size);
Nick Piggina4b06722007-10-16 01:24:48 -07002610
Linus Torvalds1da177e2005-04-16 15:20:36 -07002611 return ret;
2612}
Nick Piggin03158cd2007-10-16 01:25:25 -07002613EXPORT_SYMBOL(nobh_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002614
Nick Piggin03158cd2007-10-16 01:25:25 -07002615int nobh_write_end(struct file *file, struct address_space *mapping,
2616 loff_t pos, unsigned len, unsigned copied,
2617 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002618{
2619 struct inode *inode = page->mapping->host;
Nick Pigginefdc3132007-10-21 06:57:41 +02002620 struct buffer_head *head = fsdata;
Nick Piggin03158cd2007-10-16 01:25:25 -07002621 struct buffer_head *bh;
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002622 BUG_ON(fsdata != NULL && page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623
Dave Kleikampd4cf1092009-02-06 14:59:26 -06002624 if (unlikely(copied < len) && head)
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002625 attach_nobh_buffers(page, head);
2626 if (page_has_buffers(page))
2627 return generic_write_end(file, mapping, pos, len,
2628 copied, page, fsdata);
Nick Piggina4b06722007-10-16 01:24:48 -07002629
Nick Piggin22c8ca72007-02-20 13:58:09 -08002630 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002631 set_page_dirty(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002632 if (pos+copied > inode->i_size) {
2633 i_size_write(inode, pos+copied);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002634 mark_inode_dirty(inode);
2635 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002636
2637 unlock_page(page);
2638 page_cache_release(page);
2639
Nick Piggin03158cd2007-10-16 01:25:25 -07002640 while (head) {
2641 bh = head;
2642 head = head->b_this_page;
2643 free_buffer_head(bh);
2644 }
2645
2646 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647}
Nick Piggin03158cd2007-10-16 01:25:25 -07002648EXPORT_SYMBOL(nobh_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002649
2650/*
2651 * nobh_writepage() - based on block_full_write_page() except
2652 * that it tries to operate without attaching bufferheads to
2653 * the page.
2654 */
2655int nobh_writepage(struct page *page, get_block_t *get_block,
2656 struct writeback_control *wbc)
2657{
2658 struct inode * const inode = page->mapping->host;
2659 loff_t i_size = i_size_read(inode);
2660 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2661 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002662 int ret;
2663
2664 /* Is the page fully inside i_size? */
2665 if (page->index < end_index)
2666 goto out;
2667
2668 /* Is the page fully outside i_size? (truncate in progress) */
2669 offset = i_size & (PAGE_CACHE_SIZE-1);
2670 if (page->index >= end_index+1 || !offset) {
2671 /*
2672 * The page may have dirty, unmapped buffers. For example,
2673 * they may have been added in ext3_writepage(). Make them
2674 * freeable here, so the page does not leak.
2675 */
2676#if 0
2677 /* Not really sure about this - do we need this ? */
2678 if (page->mapping->a_ops->invalidatepage)
2679 page->mapping->a_ops->invalidatepage(page, offset);
2680#endif
2681 unlock_page(page);
2682 return 0; /* don't care */
2683 }
2684
2685 /*
2686 * The page straddles i_size. It must be zeroed out on each and every
2687 * writepage invocation because it may be mmapped. "A file is mapped
2688 * in multiples of the page size. For a file that is not a multiple of
2689 * the page size, the remaining memory is zeroed when mapped, and
2690 * writes to that region are not written out to the file."
2691 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002692 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002693out:
2694 ret = mpage_writepage(page, get_block, wbc);
2695 if (ret == -EAGAIN)
Chris Mason35c80d52009-04-15 13:22:38 -04002696 ret = __block_write_full_page(inode, page, get_block, wbc,
2697 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002698 return ret;
2699}
2700EXPORT_SYMBOL(nobh_writepage);
2701
Nick Piggin03158cd2007-10-16 01:25:25 -07002702int nobh_truncate_page(struct address_space *mapping,
2703 loff_t from, get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002704{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002705 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2706 unsigned offset = from & (PAGE_CACHE_SIZE-1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002707 unsigned blocksize;
2708 sector_t iblock;
2709 unsigned length, pos;
2710 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002711 struct page *page;
Nick Piggin03158cd2007-10-16 01:25:25 -07002712 struct buffer_head map_bh;
2713 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002714
Nick Piggin03158cd2007-10-16 01:25:25 -07002715 blocksize = 1 << inode->i_blkbits;
2716 length = offset & (blocksize - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002717
Nick Piggin03158cd2007-10-16 01:25:25 -07002718 /* Block boundary? Nothing to do */
2719 if (!length)
2720 return 0;
2721
2722 length = blocksize - length;
2723 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2724
Linus Torvalds1da177e2005-04-16 15:20:36 -07002725 page = grab_cache_page(mapping, index);
Nick Piggin03158cd2007-10-16 01:25:25 -07002726 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002727 if (!page)
2728 goto out;
2729
Nick Piggin03158cd2007-10-16 01:25:25 -07002730 if (page_has_buffers(page)) {
2731has_buffers:
2732 unlock_page(page);
2733 page_cache_release(page);
2734 return block_truncate_page(mapping, from, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002735 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002736
2737 /* Find the buffer that contains "offset" */
2738 pos = blocksize;
2739 while (offset >= pos) {
2740 iblock++;
2741 pos += blocksize;
2742 }
2743
Theodore Ts'o460bcf52009-05-12 07:37:56 -04002744 map_bh.b_size = blocksize;
2745 map_bh.b_state = 0;
Nick Piggin03158cd2007-10-16 01:25:25 -07002746 err = get_block(inode, iblock, &map_bh, 0);
2747 if (err)
2748 goto unlock;
2749 /* unmapped? It's a hole - nothing to do */
2750 if (!buffer_mapped(&map_bh))
2751 goto unlock;
2752
2753 /* Ok, it's mapped. Make sure it's up-to-date */
2754 if (!PageUptodate(page)) {
2755 err = mapping->a_ops->readpage(NULL, page);
2756 if (err) {
2757 page_cache_release(page);
2758 goto out;
2759 }
2760 lock_page(page);
2761 if (!PageUptodate(page)) {
2762 err = -EIO;
2763 goto unlock;
2764 }
2765 if (page_has_buffers(page))
2766 goto has_buffers;
2767 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002768 zero_user(page, offset, length);
Nick Piggin03158cd2007-10-16 01:25:25 -07002769 set_page_dirty(page);
2770 err = 0;
2771
2772unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002773 unlock_page(page);
2774 page_cache_release(page);
2775out:
Nick Piggin03158cd2007-10-16 01:25:25 -07002776 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002777}
2778EXPORT_SYMBOL(nobh_truncate_page);
2779
2780int block_truncate_page(struct address_space *mapping,
2781 loff_t from, get_block_t *get_block)
2782{
2783 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2784 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2785 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002786 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002787 unsigned length, pos;
2788 struct inode *inode = mapping->host;
2789 struct page *page;
2790 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002791 int err;
2792
2793 blocksize = 1 << inode->i_blkbits;
2794 length = offset & (blocksize - 1);
2795
2796 /* Block boundary? Nothing to do */
2797 if (!length)
2798 return 0;
2799
2800 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002801 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002802
2803 page = grab_cache_page(mapping, index);
2804 err = -ENOMEM;
2805 if (!page)
2806 goto out;
2807
2808 if (!page_has_buffers(page))
2809 create_empty_buffers(page, blocksize, 0);
2810
2811 /* Find the buffer that contains "offset" */
2812 bh = page_buffers(page);
2813 pos = blocksize;
2814 while (offset >= pos) {
2815 bh = bh->b_this_page;
2816 iblock++;
2817 pos += blocksize;
2818 }
2819
2820 err = 0;
2821 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002822 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823 err = get_block(inode, iblock, bh, 0);
2824 if (err)
2825 goto unlock;
2826 /* unmapped? It's a hole - nothing to do */
2827 if (!buffer_mapped(bh))
2828 goto unlock;
2829 }
2830
2831 /* Ok, it's mapped. Make sure it's up-to-date */
2832 if (PageUptodate(page))
2833 set_buffer_uptodate(bh);
2834
David Chinner33a266d2007-02-12 00:51:41 -08002835 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836 err = -EIO;
2837 ll_rw_block(READ, 1, &bh);
2838 wait_on_buffer(bh);
2839 /* Uhhuh. Read error. Complain and punt. */
2840 if (!buffer_uptodate(bh))
2841 goto unlock;
2842 }
2843
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002844 zero_user(page, offset, length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002845 mark_buffer_dirty(bh);
2846 err = 0;
2847
2848unlock:
2849 unlock_page(page);
2850 page_cache_release(page);
2851out:
2852 return err;
2853}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002854EXPORT_SYMBOL(block_truncate_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002855
2856/*
2857 * The generic ->writepage function for buffer-backed address_spaces
Chris Mason35c80d52009-04-15 13:22:38 -04002858 * this form passes in the end_io handler used to finish the IO.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002859 */
Chris Mason35c80d52009-04-15 13:22:38 -04002860int block_write_full_page_endio(struct page *page, get_block_t *get_block,
2861 struct writeback_control *wbc, bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002862{
2863 struct inode * const inode = page->mapping->host;
2864 loff_t i_size = i_size_read(inode);
2865 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2866 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002867
2868 /* Is the page fully inside i_size? */
2869 if (page->index < end_index)
Chris Mason35c80d52009-04-15 13:22:38 -04002870 return __block_write_full_page(inode, page, get_block, wbc,
2871 handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002872
2873 /* Is the page fully outside i_size? (truncate in progress) */
2874 offset = i_size & (PAGE_CACHE_SIZE-1);
2875 if (page->index >= end_index+1 || !offset) {
2876 /*
2877 * The page may have dirty, unmapped buffers. For example,
2878 * they may have been added in ext3_writepage(). Make them
2879 * freeable here, so the page does not leak.
2880 */
Jan Karaaaa40592005-10-30 15:00:16 -08002881 do_invalidatepage(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002882 unlock_page(page);
2883 return 0; /* don't care */
2884 }
2885
2886 /*
2887 * The page straddles i_size. It must be zeroed out on each and every
Adam Buchbinder2a61aa42009-12-11 16:35:40 -05002888 * writepage invocation because it may be mmapped. "A file is mapped
Linus Torvalds1da177e2005-04-16 15:20:36 -07002889 * in multiples of the page size. For a file that is not a multiple of
2890 * the page size, the remaining memory is zeroed when mapped, and
2891 * writes to that region are not written out to the file."
2892 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002893 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Chris Mason35c80d52009-04-15 13:22:38 -04002894 return __block_write_full_page(inode, page, get_block, wbc, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002895}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002896EXPORT_SYMBOL(block_write_full_page_endio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002897
Chris Mason35c80d52009-04-15 13:22:38 -04002898/*
2899 * The generic ->writepage function for buffer-backed address_spaces
2900 */
2901int block_write_full_page(struct page *page, get_block_t *get_block,
2902 struct writeback_control *wbc)
2903{
2904 return block_write_full_page_endio(page, get_block, wbc,
2905 end_buffer_async_write);
2906}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002907EXPORT_SYMBOL(block_write_full_page);
Chris Mason35c80d52009-04-15 13:22:38 -04002908
Linus Torvalds1da177e2005-04-16 15:20:36 -07002909sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2910 get_block_t *get_block)
2911{
2912 struct buffer_head tmp;
2913 struct inode *inode = mapping->host;
2914 tmp.b_state = 0;
2915 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002916 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002917 get_block(inode, block, &tmp, 0);
2918 return tmp.b_blocknr;
2919}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002920EXPORT_SYMBOL(generic_block_bmap);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002921
NeilBrown6712ecf2007-09-27 12:47:43 +02002922static void end_bio_bh_io_sync(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002923{
2924 struct buffer_head *bh = bio->bi_private;
2925
Linus Torvalds1da177e2005-04-16 15:20:36 -07002926 if (err == -EOPNOTSUPP) {
2927 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
2928 set_bit(BH_Eopnotsupp, &bh->b_state);
2929 }
2930
Keith Mannthey08bafc02008-11-25 10:24:35 +01002931 if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2932 set_bit(BH_Quiet, &bh->b_state);
2933
Linus Torvalds1da177e2005-04-16 15:20:36 -07002934 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2935 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002936}
2937
2938int submit_bh(int rw, struct buffer_head * bh)
2939{
2940 struct bio *bio;
2941 int ret = 0;
2942
2943 BUG_ON(!buffer_locked(bh));
2944 BUG_ON(!buffer_mapped(bh));
2945 BUG_ON(!bh->b_end_io);
Aneesh Kumar K.V8fb0e342009-05-12 16:22:37 -04002946 BUG_ON(buffer_delay(bh));
2947 BUG_ON(buffer_unwritten(bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002948
Jens Axboe48fd4f92008-08-22 10:00:36 +02002949 /*
2950 * Mask in barrier bit for a write (could be either a WRITE or a
2951 * WRITE_SYNC
2952 */
2953 if (buffer_ordered(bh) && (rw & WRITE))
2954 rw |= WRITE_BARRIER;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002955
2956 /*
Jens Axboe48fd4f92008-08-22 10:00:36 +02002957 * Only clear out a write error when rewriting
Linus Torvalds1da177e2005-04-16 15:20:36 -07002958 */
Jens Axboe48fd4f92008-08-22 10:00:36 +02002959 if (test_set_buffer_req(bh) && (rw & WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960 clear_buffer_write_io_error(bh);
2961
2962 /*
2963 * from here on down, it's all bio -- do the initial mapping,
2964 * submit_bio -> generic_make_request may further map this bio around
2965 */
2966 bio = bio_alloc(GFP_NOIO, 1);
2967
2968 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
2969 bio->bi_bdev = bh->b_bdev;
2970 bio->bi_io_vec[0].bv_page = bh->b_page;
2971 bio->bi_io_vec[0].bv_len = bh->b_size;
2972 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
2973
2974 bio->bi_vcnt = 1;
2975 bio->bi_idx = 0;
2976 bio->bi_size = bh->b_size;
2977
2978 bio->bi_end_io = end_bio_bh_io_sync;
2979 bio->bi_private = bh;
2980
2981 bio_get(bio);
2982 submit_bio(rw, bio);
2983
2984 if (bio_flagged(bio, BIO_EOPNOTSUPP))
2985 ret = -EOPNOTSUPP;
2986
2987 bio_put(bio);
2988 return ret;
2989}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07002990EXPORT_SYMBOL(submit_bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002991
2992/**
2993 * ll_rw_block: low-level access to block devices (DEPRECATED)
Jan Karaa7662232005-09-06 15:19:10 -07002994 * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002995 * @nr: number of &struct buffer_heads in the array
2996 * @bhs: array of pointers to &struct buffer_head
2997 *
Jan Karaa7662232005-09-06 15:19:10 -07002998 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
2999 * requests an I/O operation on them, either a %READ or a %WRITE. The third
3000 * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
3001 * are sent to disk. The fourth %READA option is described in the documentation
3002 * for generic_make_request() which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003003 *
3004 * This function drops any buffer that it cannot get a lock on (with the
Jan Karaa7662232005-09-06 15:19:10 -07003005 * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
3006 * clean when doing a write request, and any buffer that appears to be
3007 * up-to-date when doing read request. Further it marks as clean buffers that
3008 * are processed for writing (the buffer cache won't assume that they are
3009 * actually clean until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07003010 *
3011 * ll_rw_block sets b_end_io to simple completion handler that marks
3012 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
3013 * any waiters.
3014 *
3015 * All of the buffers must be for the same device, and must also be a
3016 * multiple of the current approved size for the device.
3017 */
3018void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
3019{
3020 int i;
3021
3022 for (i = 0; i < nr; i++) {
3023 struct buffer_head *bh = bhs[i];
3024
Jens Axboe9cf6b722009-04-06 14:48:03 +02003025 if (rw == SWRITE || rw == SWRITE_SYNC || rw == SWRITE_SYNC_PLUG)
Jan Karaa7662232005-09-06 15:19:10 -07003026 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02003027 else if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003028 continue;
3029
Jens Axboe9cf6b722009-04-06 14:48:03 +02003030 if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC ||
3031 rw == SWRITE_SYNC_PLUG) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003032 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003033 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003034 get_bh(bh);
Jens Axboe18ce3752008-07-01 09:07:34 +02003035 if (rw == SWRITE_SYNC)
3036 submit_bh(WRITE_SYNC, bh);
3037 else
3038 submit_bh(WRITE, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003039 continue;
3040 }
3041 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003042 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003043 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003044 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003045 submit_bh(rw, bh);
3046 continue;
3047 }
3048 }
3049 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003050 }
3051}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003052EXPORT_SYMBOL(ll_rw_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003053
3054/*
3055 * For a data-integrity writeout, we need to wait upon any in-progress I/O
3056 * and then start new I/O and then wait upon it. The caller must have a ref on
3057 * the buffer_head.
3058 */
3059int sync_dirty_buffer(struct buffer_head *bh)
3060{
3061 int ret = 0;
3062
3063 WARN_ON(atomic_read(&bh->b_count) < 1);
3064 lock_buffer(bh);
3065 if (test_clear_buffer_dirty(bh)) {
3066 get_bh(bh);
3067 bh->b_end_io = end_buffer_write_sync;
Jens Axboe1aa2a7c2009-04-06 14:48:08 +02003068 ret = submit_bh(WRITE_SYNC, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003069 wait_on_buffer(bh);
3070 if (buffer_eopnotsupp(bh)) {
3071 clear_buffer_eopnotsupp(bh);
3072 ret = -EOPNOTSUPP;
3073 }
3074 if (!ret && !buffer_uptodate(bh))
3075 ret = -EIO;
3076 } else {
3077 unlock_buffer(bh);
3078 }
3079 return ret;
3080}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003081EXPORT_SYMBOL(sync_dirty_buffer);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003082
3083/*
3084 * try_to_free_buffers() checks if all the buffers on this particular page
3085 * are unused, and releases them if so.
3086 *
3087 * Exclusion against try_to_free_buffers may be obtained by either
3088 * locking the page or by holding its mapping's private_lock.
3089 *
3090 * If the page is dirty but all the buffers are clean then we need to
3091 * be sure to mark the page clean as well. This is because the page
3092 * may be against a block device, and a later reattachment of buffers
3093 * to a dirty page will set *all* buffers dirty. Which would corrupt
3094 * filesystem data on the same device.
3095 *
3096 * The same applies to regular filesystem pages: if all the buffers are
3097 * clean then we set the page clean and proceed. To do that, we require
3098 * total exclusion from __set_page_dirty_buffers(). That is obtained with
3099 * private_lock.
3100 *
3101 * try_to_free_buffers() is non-blocking.
3102 */
3103static inline int buffer_busy(struct buffer_head *bh)
3104{
3105 return atomic_read(&bh->b_count) |
3106 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3107}
3108
3109static int
3110drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3111{
3112 struct buffer_head *head = page_buffers(page);
3113 struct buffer_head *bh;
3114
3115 bh = head;
3116 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07003117 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003118 set_bit(AS_EIO, &page->mapping->flags);
3119 if (buffer_busy(bh))
3120 goto failed;
3121 bh = bh->b_this_page;
3122 } while (bh != head);
3123
3124 do {
3125 struct buffer_head *next = bh->b_this_page;
3126
Jan Kara535ee2f2008-02-08 04:21:59 -08003127 if (bh->b_assoc_map)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003128 __remove_assoc_queue(bh);
3129 bh = next;
3130 } while (bh != head);
3131 *buffers_to_free = head;
3132 __clear_page_buffers(page);
3133 return 1;
3134failed:
3135 return 0;
3136}
3137
3138int try_to_free_buffers(struct page *page)
3139{
3140 struct address_space * const mapping = page->mapping;
3141 struct buffer_head *buffers_to_free = NULL;
3142 int ret = 0;
3143
3144 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003145 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003146 return 0;
3147
3148 if (mapping == NULL) { /* can this still happen? */
3149 ret = drop_buffers(page, &buffers_to_free);
3150 goto out;
3151 }
3152
3153 spin_lock(&mapping->private_lock);
3154 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003155
3156 /*
3157 * If the filesystem writes its buffers by hand (eg ext3)
3158 * then we can have clean buffers against a dirty page. We
3159 * clean the page here; otherwise the VM will never notice
3160 * that the filesystem did any IO at all.
3161 *
3162 * Also, during truncate, discard_buffer will have marked all
3163 * the page's buffers clean. We discover that here and clean
3164 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11003165 *
3166 * private_lock must be held over this entire operation in order
3167 * to synchronise against __set_page_dirty_buffers and prevent the
3168 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003169 */
3170 if (ret)
3171 cancel_dirty_page(page, PAGE_CACHE_SIZE);
Nick Piggin87df7242007-01-30 14:36:27 +11003172 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003173out:
3174 if (buffers_to_free) {
3175 struct buffer_head *bh = buffers_to_free;
3176
3177 do {
3178 struct buffer_head *next = bh->b_this_page;
3179 free_buffer_head(bh);
3180 bh = next;
3181 } while (bh != buffers_to_free);
3182 }
3183 return ret;
3184}
3185EXPORT_SYMBOL(try_to_free_buffers);
3186
NeilBrown3978d712006-03-26 01:37:17 -08003187void block_sync_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003188{
3189 struct address_space *mapping;
3190
3191 smp_mb();
3192 mapping = page_mapping(page);
3193 if (mapping)
3194 blk_run_backing_dev(mapping->backing_dev_info, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003195}
H Hartley Sweeten1fe72ea2009-09-22 16:43:51 -07003196EXPORT_SYMBOL(block_sync_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003197
3198/*
3199 * There are no bdflush tunables left. But distributions are
3200 * still running obsolete flush daemons, so we terminate them here.
3201 *
3202 * Use of bdflush() is deprecated and will be removed in a future kernel.
Jens Axboe5b0830c2009-09-23 19:37:09 +02003203 * The `flush-X' kernel threads fully replace bdflush daemons and this call.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003204 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01003205SYSCALL_DEFINE2(bdflush, int, func, long, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003206{
3207 static int msg_count;
3208
3209 if (!capable(CAP_SYS_ADMIN))
3210 return -EPERM;
3211
3212 if (msg_count < 5) {
3213 msg_count++;
3214 printk(KERN_INFO
3215 "warning: process `%s' used the obsolete bdflush"
3216 " system call\n", current->comm);
3217 printk(KERN_INFO "Fix your initscripts?\n");
3218 }
3219
3220 if (func == 1)
3221 do_exit(0);
3222 return 0;
3223}
3224
3225/*
3226 * Buffer-head allocation
3227 */
Christoph Lametere18b8902006-12-06 20:33:20 -08003228static struct kmem_cache *bh_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003229
3230/*
3231 * Once the number of bh's in the machine exceeds this level, we start
3232 * stripping them in writeback.
3233 */
3234static int max_buffer_heads;
3235
3236int buffer_heads_over_limit;
3237
3238struct bh_accounting {
3239 int nr; /* Number of live bh's */
3240 int ratelimit; /* Limit cacheline bouncing */
3241};
3242
3243static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3244
3245static void recalc_bh_state(void)
3246{
3247 int i;
3248 int tot = 0;
3249
3250 if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
3251 return;
3252 __get_cpu_var(bh_accounting).ratelimit = 0;
Eric Dumazet8a143422006-03-24 03:18:10 -08003253 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003254 tot += per_cpu(bh_accounting, i).nr;
3255 buffer_heads_over_limit = (tot > max_buffer_heads);
3256}
3257
Al Virodd0fc662005-10-07 07:46:04 +01003258struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003259{
Richard Kennedy019b4d12010-03-10 15:20:33 -08003260 struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003261 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07003262 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003263 get_cpu_var(bh_accounting).nr++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003264 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003265 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003266 }
3267 return ret;
3268}
3269EXPORT_SYMBOL(alloc_buffer_head);
3270
3271void free_buffer_head(struct buffer_head *bh)
3272{
3273 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3274 kmem_cache_free(bh_cachep, bh);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003275 get_cpu_var(bh_accounting).nr--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003276 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003277 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003278}
3279EXPORT_SYMBOL(free_buffer_head);
3280
Linus Torvalds1da177e2005-04-16 15:20:36 -07003281static void buffer_exit_cpu(int cpu)
3282{
3283 int i;
3284 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3285
3286 for (i = 0; i < BH_LRU_SIZE; i++) {
3287 brelse(b->bhs[i]);
3288 b->bhs[i] = NULL;
3289 }
Eric Dumazet8a143422006-03-24 03:18:10 -08003290 get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr;
3291 per_cpu(bh_accounting, cpu).nr = 0;
3292 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003293}
3294
3295static int buffer_cpu_notify(struct notifier_block *self,
3296 unsigned long action, void *hcpu)
3297{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003298 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003299 buffer_exit_cpu((unsigned long)hcpu);
3300 return NOTIFY_OK;
3301}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003302
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003303/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003304 * bh_uptodate_or_lock - Test whether the buffer is uptodate
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003305 * @bh: struct buffer_head
3306 *
3307 * Return true if the buffer is up-to-date and false,
3308 * with the buffer locked, if not.
3309 */
3310int bh_uptodate_or_lock(struct buffer_head *bh)
3311{
3312 if (!buffer_uptodate(bh)) {
3313 lock_buffer(bh);
3314 if (!buffer_uptodate(bh))
3315 return 0;
3316 unlock_buffer(bh);
3317 }
3318 return 1;
3319}
3320EXPORT_SYMBOL(bh_uptodate_or_lock);
3321
3322/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003323 * bh_submit_read - Submit a locked buffer for reading
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003324 * @bh: struct buffer_head
3325 *
3326 * Returns zero on success and -EIO on error.
3327 */
3328int bh_submit_read(struct buffer_head *bh)
3329{
3330 BUG_ON(!buffer_locked(bh));
3331
3332 if (buffer_uptodate(bh)) {
3333 unlock_buffer(bh);
3334 return 0;
3335 }
3336
3337 get_bh(bh);
3338 bh->b_end_io = end_buffer_read_sync;
3339 submit_bh(READ, bh);
3340 wait_on_buffer(bh);
3341 if (buffer_uptodate(bh))
3342 return 0;
3343 return -EIO;
3344}
3345EXPORT_SYMBOL(bh_submit_read);
3346
Linus Torvalds1da177e2005-04-16 15:20:36 -07003347void __init buffer_init(void)
3348{
3349 int nrpages;
3350
Christoph Lameterb98938c2008-02-04 22:28:36 -08003351 bh_cachep = kmem_cache_create("buffer_head",
3352 sizeof(struct buffer_head), 0,
3353 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3354 SLAB_MEM_SPREAD),
Richard Kennedy019b4d12010-03-10 15:20:33 -08003355 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003356
3357 /*
3358 * Limit the bh occupancy to 10% of ZONE_NORMAL
3359 */
3360 nrpages = (nr_free_buffer_pages() * 10) / 100;
3361 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3362 hotcpu_notifier(buffer_cpu_notify, 0);
3363}