blob: aa68206bd517929ccd1a7f338889ba0575ab4c30 [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}
55
56static int sync_buffer(void *word)
57{
58 struct block_device *bd;
59 struct buffer_head *bh
60 = container_of(word, struct buffer_head, b_state);
61
62 smp_mb();
63 bd = bh->b_bdev;
64 if (bd)
65 blk_run_address_space(bd->bd_inode->i_mapping);
66 io_schedule();
67 return 0;
68}
69
70void fastcall __lock_buffer(struct buffer_head *bh)
71{
72 wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer,
73 TASK_UNINTERRUPTIBLE);
74}
75EXPORT_SYMBOL(__lock_buffer);
76
77void fastcall unlock_buffer(struct buffer_head *bh)
78{
Nick Piggin72ed3d02007-02-10 01:46:22 -080079 smp_mb__before_clear_bit();
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 clear_buffer_locked(bh);
81 smp_mb__after_clear_bit();
82 wake_up_bit(&bh->b_state, BH_Lock);
83}
84
85/*
86 * Block until a buffer comes unlocked. This doesn't stop it
87 * from becoming locked again - you have to lock it yourself
88 * if you want to preserve its state.
89 */
90void __wait_on_buffer(struct buffer_head * bh)
91{
92 wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE);
93}
94
95static void
96__clear_page_buffers(struct page *page)
97{
98 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070099 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 page_cache_release(page);
101}
102
103static void buffer_io_error(struct buffer_head *bh)
104{
105 char b[BDEVNAME_SIZE];
106
107 printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
108 bdevname(bh->b_bdev, b),
109 (unsigned long long)bh->b_blocknr);
110}
111
112/*
113 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
114 * unlock the buffer. This is what ll_rw_block uses too.
115 */
116void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
117{
118 if (uptodate) {
119 set_buffer_uptodate(bh);
120 } else {
121 /* This happens, due to failed READA attempts. */
122 clear_buffer_uptodate(bh);
123 }
124 unlock_buffer(bh);
125 put_bh(bh);
126}
127
128void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
129{
130 char b[BDEVNAME_SIZE];
131
132 if (uptodate) {
133 set_buffer_uptodate(bh);
134 } else {
135 if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
136 buffer_io_error(bh);
137 printk(KERN_WARNING "lost page write due to "
138 "I/O error on %s\n",
139 bdevname(bh->b_bdev, b));
140 }
141 set_buffer_write_io_error(bh);
142 clear_buffer_uptodate(bh);
143 }
144 unlock_buffer(bh);
145 put_bh(bh);
146}
147
148/*
149 * Write out and wait upon all the dirty data associated with a block
150 * device via its mapping. Does not take the superblock lock.
151 */
152int sync_blockdev(struct block_device *bdev)
153{
154 int ret = 0;
155
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800156 if (bdev)
157 ret = filemap_write_and_wait(bdev->bd_inode->i_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158 return ret;
159}
160EXPORT_SYMBOL(sync_blockdev);
161
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162/*
163 * Write out and wait upon all dirty data associated with this
164 * device. Filesystem data as well as the underlying block
165 * device. Takes the superblock lock.
166 */
167int fsync_bdev(struct block_device *bdev)
168{
169 struct super_block *sb = get_super(bdev);
170 if (sb) {
171 int res = fsync_super(sb);
172 drop_super(sb);
173 return res;
174 }
175 return sync_blockdev(bdev);
176}
177
178/**
179 * freeze_bdev -- lock a filesystem and force it into a consistent state
180 * @bdev: blockdevice to lock
181 *
David Chinnerf73ca1b2007-01-10 23:15:41 -0800182 * This takes the block device bd_mount_sem to make sure no new mounts
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183 * happen on bdev until thaw_bdev() is called.
184 * If a superblock is found on this device, we take the s_umount semaphore
185 * on it to make sure nobody unmounts until the snapshot creation is done.
186 */
187struct super_block *freeze_bdev(struct block_device *bdev)
188{
189 struct super_block *sb;
190
David Chinnerf73ca1b2007-01-10 23:15:41 -0800191 down(&bdev->bd_mount_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 sb = get_super(bdev);
193 if (sb && !(sb->s_flags & MS_RDONLY)) {
194 sb->s_frozen = SB_FREEZE_WRITE;
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700195 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196
OGAWA Hirofumid25b9a12006-03-25 03:07:44 -0800197 __fsync_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198
199 sb->s_frozen = SB_FREEZE_TRANS;
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700200 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201
202 sync_blockdev(sb->s_bdev);
203
204 if (sb->s_op->write_super_lockfs)
205 sb->s_op->write_super_lockfs(sb);
206 }
207
208 sync_blockdev(bdev);
209 return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */
210}
211EXPORT_SYMBOL(freeze_bdev);
212
213/**
214 * thaw_bdev -- unlock filesystem
215 * @bdev: blockdevice to unlock
216 * @sb: associated superblock
217 *
218 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
219 */
220void thaw_bdev(struct block_device *bdev, struct super_block *sb)
221{
222 if (sb) {
223 BUG_ON(sb->s_bdev != bdev);
224
225 if (sb->s_op->unlockfs)
226 sb->s_op->unlockfs(sb);
227 sb->s_frozen = SB_UNFROZEN;
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700228 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 wake_up(&sb->s_wait_unfrozen);
230 drop_super(sb);
231 }
232
David Chinnerf73ca1b2007-01-10 23:15:41 -0800233 up(&bdev->bd_mount_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234}
235EXPORT_SYMBOL(thaw_bdev);
236
237/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 * Various filesystems appear to want __find_get_block to be non-blocking.
239 * But it's the page lock which protects the buffers. To get around this,
240 * we get exclusion from try_to_free_buffers with the blockdev mapping's
241 * private_lock.
242 *
243 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
244 * may be quite high. This code could TryLock the page, and if that
245 * succeeds, there is no need to take private_lock. (But if
246 * private_lock is contended then so is mapping->tree_lock).
247 */
248static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800249__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250{
251 struct inode *bd_inode = bdev->bd_inode;
252 struct address_space *bd_mapping = bd_inode->i_mapping;
253 struct buffer_head *ret = NULL;
254 pgoff_t index;
255 struct buffer_head *bh;
256 struct buffer_head *head;
257 struct page *page;
258 int all_mapped = 1;
259
260 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
261 page = find_get_page(bd_mapping, index);
262 if (!page)
263 goto out;
264
265 spin_lock(&bd_mapping->private_lock);
266 if (!page_has_buffers(page))
267 goto out_unlock;
268 head = page_buffers(page);
269 bh = head;
270 do {
271 if (bh->b_blocknr == block) {
272 ret = bh;
273 get_bh(bh);
274 goto out_unlock;
275 }
276 if (!buffer_mapped(bh))
277 all_mapped = 0;
278 bh = bh->b_this_page;
279 } while (bh != head);
280
281 /* we might be here because some of the buffers on this page are
282 * not mapped. This is due to various races between
283 * file io on the block device and getblk. It gets dealt with
284 * elsewhere, don't buffer_error if we had some unmapped buffers
285 */
286 if (all_mapped) {
287 printk("__find_get_block_slow() failed. "
288 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800289 (unsigned long long)block,
290 (unsigned long long)bh->b_blocknr);
291 printk("b_state=0x%08lx, b_size=%zu\n",
292 bh->b_state, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
294 }
295out_unlock:
296 spin_unlock(&bd_mapping->private_lock);
297 page_cache_release(page);
298out:
299 return ret;
300}
301
302/* If invalidate_buffers() will trash dirty buffers, it means some kind
303 of fs corruption is going on. Trashing dirty data always imply losing
304 information that was supposed to be just stored on the physical layer
305 by the user.
306
307 Thus invalidate_buffers in general usage is not allwowed to trash
308 dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
309 be preserved. These buffers are simply skipped.
310
311 We also skip buffers which are still in use. For example this can
312 happen if a userspace program is reading the block device.
313
314 NOTE: In the case where the user removed a removable-media-disk even if
315 there's still dirty data not synced on disk (due a bug in the device driver
316 or due an error of the user), by not destroying the dirty buffers we could
317 generate corruption also on the next media inserted, thus a parameter is
318 necessary to handle this case in the most safe way possible (trying
319 to not corrupt also the new disk inserted with the data belonging to
320 the old now corrupted disk). Also for the ramdisk the natural thing
321 to do in order to release the ramdisk memory is to destroy dirty buffers.
322
323 These are two special cases. Normal usage imply the device driver
324 to issue a sync on the device (without waiting I/O completion) and
325 then an invalidate_buffers call that doesn't trash dirty buffers.
326
327 For handling cache coherency with the blkdev pagecache the 'update' case
328 is been introduced. It is needed to re-read from disk any pinned
329 buffer. NOTE: re-reading from disk is destructive so we can do it only
330 when we assume nobody is changing the buffercache under our I/O and when
331 we think the disk contains more recent information than the buffercache.
332 The update == 1 pass marks the buffers we need to update, the update == 2
333 pass does the actual I/O. */
Peter Zijlstraf98393a2007-05-06 14:49:54 -0700334void invalidate_bdev(struct block_device *bdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335{
Andrew Morton0e1dfc62006-07-30 03:03:28 -0700336 struct address_space *mapping = bdev->bd_inode->i_mapping;
337
338 if (mapping->nrpages == 0)
339 return;
340
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 invalidate_bh_lrus();
Andrew Mortonfc0ecff2007-02-10 01:45:39 -0800342 invalidate_mapping_pages(mapping, 0, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343}
344
345/*
346 * Kick pdflush then try to free up some ZONE_NORMAL memory.
347 */
348static void free_more_memory(void)
349{
350 struct zone **zones;
351 pg_data_t *pgdat;
352
Pekka J Enberg687a21c2005-06-28 20:44:55 -0700353 wakeup_pdflush(1024);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 yield();
355
KAMEZAWA Hiroyukiec936fc2006-03-27 01:15:59 -0800356 for_each_online_pgdat(pgdat) {
Al Viroaf4ca452005-10-21 02:55:38 -0400357 zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358 if (*zones)
Darren Hart1ad539b2005-06-21 17:14:53 -0700359 try_to_free_pages(zones, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 }
361}
362
363/*
364 * I/O completion handler for block_read_full_page() - pages
365 * which come unlocked at the end of I/O.
366 */
367static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
368{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700370 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 struct buffer_head *tmp;
372 struct page *page;
373 int page_uptodate = 1;
374
375 BUG_ON(!buffer_async_read(bh));
376
377 page = bh->b_page;
378 if (uptodate) {
379 set_buffer_uptodate(bh);
380 } else {
381 clear_buffer_uptodate(bh);
382 if (printk_ratelimit())
383 buffer_io_error(bh);
384 SetPageError(page);
385 }
386
387 /*
388 * Be _very_ careful from here on. Bad things can happen if
389 * two buffer heads end IO at almost the same time and both
390 * decide that the page is now completely done.
391 */
Nick Piggina3972202005-07-07 17:56:56 -0700392 first = page_buffers(page);
393 local_irq_save(flags);
394 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 clear_buffer_async_read(bh);
396 unlock_buffer(bh);
397 tmp = bh;
398 do {
399 if (!buffer_uptodate(tmp))
400 page_uptodate = 0;
401 if (buffer_async_read(tmp)) {
402 BUG_ON(!buffer_locked(tmp));
403 goto still_busy;
404 }
405 tmp = tmp->b_this_page;
406 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700407 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
408 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
410 /*
411 * If none of the buffers had errors and they are all
412 * uptodate then we can set the page uptodate.
413 */
414 if (page_uptodate && !PageError(page))
415 SetPageUptodate(page);
416 unlock_page(page);
417 return;
418
419still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700420 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
421 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422 return;
423}
424
425/*
426 * Completion handler for block_write_full_page() - pages which are unlocked
427 * during I/O, and which have PageWriteback cleared upon I/O completion.
428 */
Adrian Bunkb6cd0b72006-06-27 02:53:54 -0700429static void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430{
431 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700433 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700434 struct buffer_head *tmp;
435 struct page *page;
436
437 BUG_ON(!buffer_async_write(bh));
438
439 page = bh->b_page;
440 if (uptodate) {
441 set_buffer_uptodate(bh);
442 } else {
443 if (printk_ratelimit()) {
444 buffer_io_error(bh);
445 printk(KERN_WARNING "lost page write due to "
446 "I/O error on %s\n",
447 bdevname(bh->b_bdev, b));
448 }
449 set_bit(AS_EIO, &page->mapping->flags);
Jan Kara58ff4072006-10-17 00:10:19 -0700450 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 clear_buffer_uptodate(bh);
452 SetPageError(page);
453 }
454
Nick Piggina3972202005-07-07 17:56:56 -0700455 first = page_buffers(page);
456 local_irq_save(flags);
457 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459 clear_buffer_async_write(bh);
460 unlock_buffer(bh);
461 tmp = bh->b_this_page;
462 while (tmp != bh) {
463 if (buffer_async_write(tmp)) {
464 BUG_ON(!buffer_locked(tmp));
465 goto still_busy;
466 }
467 tmp = tmp->b_this_page;
468 }
Nick Piggina3972202005-07-07 17:56:56 -0700469 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
470 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 end_page_writeback(page);
472 return;
473
474still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700475 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
476 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 return;
478}
479
480/*
481 * If a page's buffers are under async readin (end_buffer_async_read
482 * completion) then there is a possibility that another thread of
483 * control could lock one of the buffers after it has completed
484 * but while some of the other buffers have not completed. This
485 * locked buffer would confuse end_buffer_async_read() into not unlocking
486 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
487 * that this buffer is not under async I/O.
488 *
489 * The page comes unlocked when it has no locked buffer_async buffers
490 * left.
491 *
492 * PageLocked prevents anyone starting new async I/O reads any of
493 * the buffers.
494 *
495 * PageWriteback is used to prevent simultaneous writeout of the same
496 * page.
497 *
498 * PageLocked prevents anyone from starting writeback of a page which is
499 * under read I/O (PageWriteback is only ever set against a locked page).
500 */
501static void mark_buffer_async_read(struct buffer_head *bh)
502{
503 bh->b_end_io = end_buffer_async_read;
504 set_buffer_async_read(bh);
505}
506
507void mark_buffer_async_write(struct buffer_head *bh)
508{
509 bh->b_end_io = end_buffer_async_write;
510 set_buffer_async_write(bh);
511}
512EXPORT_SYMBOL(mark_buffer_async_write);
513
514
515/*
516 * fs/buffer.c contains helper functions for buffer-backed address space's
517 * fsync functions. A common requirement for buffer-based filesystems is
518 * that certain data from the backing blockdev needs to be written out for
519 * a successful fsync(). For example, ext2 indirect blocks need to be
520 * written back and waited upon before fsync() returns.
521 *
522 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
523 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
524 * management of a list of dependent buffers at ->i_mapping->private_list.
525 *
526 * Locking is a little subtle: try_to_free_buffers() will remove buffers
527 * from their controlling inode's queue when they are being freed. But
528 * try_to_free_buffers() will be operating against the *blockdev* mapping
529 * at the time, not against the S_ISREG file which depends on those buffers.
530 * So the locking for private_list is via the private_lock in the address_space
531 * which backs the buffers. Which is different from the address_space
532 * against which the buffers are listed. So for a particular address_space,
533 * mapping->private_lock does *not* protect mapping->private_list! In fact,
534 * mapping->private_list will always be protected by the backing blockdev's
535 * ->private_lock.
536 *
537 * Which introduces a requirement: all buffers on an address_space's
538 * ->private_list must be from the same address_space: the blockdev's.
539 *
540 * address_spaces which do not place buffers at ->private_list via these
541 * utility functions are free to use private_lock and private_list for
542 * whatever they want. The only requirement is that list_empty(private_list)
543 * be true at clear_inode() time.
544 *
545 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
546 * filesystems should do that. invalidate_inode_buffers() should just go
547 * BUG_ON(!list_empty).
548 *
549 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
550 * take an address_space, not an inode. And it should be called
551 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
552 * queued up.
553 *
554 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
555 * list if it is already on a list. Because if the buffer is on a list,
556 * it *must* already be on the right one. If not, the filesystem is being
557 * silly. This will save a ton of locking. But first we have to ensure
558 * that buffers are taken *off* the old inode's list when they are freed
559 * (presumably in truncate). That requires careful auditing of all
560 * filesystems (do it inside bforget()). It could also be done by bringing
561 * b_inode back.
562 */
563
564/*
565 * The buffer's backing address_space's private_lock must be held
566 */
567static inline void __remove_assoc_queue(struct buffer_head *bh)
568{
569 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -0700570 WARN_ON(!bh->b_assoc_map);
571 if (buffer_write_io_error(bh))
572 set_bit(AS_EIO, &bh->b_assoc_map->flags);
573 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574}
575
576int inode_has_buffers(struct inode *inode)
577{
578 return !list_empty(&inode->i_data.private_list);
579}
580
581/*
582 * osync is designed to support O_SYNC io. It waits synchronously for
583 * all already-submitted IO to complete, but does not queue any new
584 * writes to the disk.
585 *
586 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
587 * you dirty the buffers, and then use osync_inode_buffers to wait for
588 * completion. Any other dirty buffers which are not yet queued for
589 * write will not be flushed to disk by the osync.
590 */
591static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
592{
593 struct buffer_head *bh;
594 struct list_head *p;
595 int err = 0;
596
597 spin_lock(lock);
598repeat:
599 list_for_each_prev(p, list) {
600 bh = BH_ENTRY(p);
601 if (buffer_locked(bh)) {
602 get_bh(bh);
603 spin_unlock(lock);
604 wait_on_buffer(bh);
605 if (!buffer_uptodate(bh))
606 err = -EIO;
607 brelse(bh);
608 spin_lock(lock);
609 goto repeat;
610 }
611 }
612 spin_unlock(lock);
613 return err;
614}
615
616/**
617 * sync_mapping_buffers - write out and wait upon a mapping's "associated"
618 * buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700619 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 *
621 * Starts I/O against the buffers at mapping->private_list, and waits upon
622 * that I/O.
623 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700624 * Basically, this is a convenience function for fsync().
625 * @mapping is a file or directory which needs those buffers to be written for
626 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 */
628int sync_mapping_buffers(struct address_space *mapping)
629{
630 struct address_space *buffer_mapping = mapping->assoc_mapping;
631
632 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
633 return 0;
634
635 return fsync_buffers_list(&buffer_mapping->private_lock,
636 &mapping->private_list);
637}
638EXPORT_SYMBOL(sync_mapping_buffers);
639
640/*
641 * Called when we've recently written block `bblock', and it is known that
642 * `bblock' was for a buffer_boundary() buffer. This means that the block at
643 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
644 * dirty, schedule it for IO. So that indirects merge nicely with their data.
645 */
646void write_boundary_block(struct block_device *bdev,
647 sector_t bblock, unsigned blocksize)
648{
649 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
650 if (bh) {
651 if (buffer_dirty(bh))
652 ll_rw_block(WRITE, 1, &bh);
653 put_bh(bh);
654 }
655}
656
657void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
658{
659 struct address_space *mapping = inode->i_mapping;
660 struct address_space *buffer_mapping = bh->b_page->mapping;
661
662 mark_buffer_dirty(bh);
663 if (!mapping->assoc_mapping) {
664 mapping->assoc_mapping = buffer_mapping;
665 } else {
Eric Sesterhenne827f922006-03-26 18:24:46 +0200666 BUG_ON(mapping->assoc_mapping != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667 }
668 if (list_empty(&bh->b_assoc_buffers)) {
669 spin_lock(&buffer_mapping->private_lock);
670 list_move_tail(&bh->b_assoc_buffers,
671 &mapping->private_list);
Jan Kara58ff4072006-10-17 00:10:19 -0700672 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 spin_unlock(&buffer_mapping->private_lock);
674 }
675}
676EXPORT_SYMBOL(mark_buffer_dirty_inode);
677
678/*
679 * Add a page to the dirty page list.
680 *
681 * It is a sad fact of life that this function is called from several places
682 * deeply under spinlocking. It may not sleep.
683 *
684 * If the page has buffers, the uptodate buffers are set dirty, to preserve
685 * dirty-state coherency between the page and the buffers. It the page does
686 * not have buffers then when they are later attached they will all be set
687 * dirty.
688 *
689 * The buffers are dirtied before the page is dirtied. There's a small race
690 * window in which a writepage caller may see the page cleanness but not the
691 * buffer dirtiness. That's fine. If this code were to set the page dirty
692 * before the buffers, a concurrent writepage caller could clear the page dirty
693 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
694 * page on the dirty page list.
695 *
696 * We use private_lock to lock against try_to_free_buffers while using the
697 * page's buffer list. Also use this to protect against clean buffers being
698 * added to the page after it was set dirty.
699 *
700 * FIXME: may need to call ->reservepage here as well. That's rather up to the
701 * address_space though.
702 */
703int __set_page_dirty_buffers(struct page *page)
704{
Nick Pigginebf7a222006-10-10 04:36:54 +0200705 struct address_space * const mapping = page_mapping(page);
706
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 }
720 spin_unlock(&mapping->private_lock);
721
Andrew Morton8c085402006-12-10 02:19:24 -0800722 if (TestSetPageDirty(page))
723 return 0;
724
725 write_lock_irq(&mapping->tree_lock);
726 if (page->mapping) { /* Race with truncate? */
Andrew Morton55e829a2006-12-10 02:19:27 -0800727 if (mapping_cap_account_dirty(mapping)) {
Andrew Morton8c085402006-12-10 02:19:24 -0800728 __inc_zone_page_state(page, NR_FILE_DIRTY);
Andrew Morton55e829a2006-12-10 02:19:27 -0800729 task_io_account_write(PAGE_CACHE_SIZE);
730 }
Andrew Morton8c085402006-12-10 02:19:24 -0800731 radix_tree_tag_set(&mapping->page_tree,
732 page_index(page), PAGECACHE_TAG_DIRTY);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 }
Andrew Morton8c085402006-12-10 02:19:24 -0800734 write_unlock_irq(&mapping->tree_lock);
735 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
736 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737}
738EXPORT_SYMBOL(__set_page_dirty_buffers);
739
740/*
741 * Write out and wait upon a list of buffers.
742 *
743 * We have conflicting pressures: we want to make sure that all
744 * initially dirty buffers get waited on, but that any subsequently
745 * dirtied buffers don't. After all, we don't want fsync to last
746 * forever if somebody is actively writing to the file.
747 *
748 * Do this in two main stages: first we copy dirty buffers to a
749 * temporary inode list, queueing the writes as we go. Then we clean
750 * up, waiting for those writes to complete.
751 *
752 * During this second stage, any subsequent updates to the file may end
753 * up refiling the buffer on the original inode's dirty list again, so
754 * there is a chance we will end up with a buffer queued for write but
755 * not yet completed on that list. So, as a final cleanup we go through
756 * the osync code to catch these locked, dirty buffers without requeuing
757 * any newly dirty buffers for write.
758 */
759static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
760{
761 struct buffer_head *bh;
762 struct list_head tmp;
763 int err = 0, err2;
764
765 INIT_LIST_HEAD(&tmp);
766
767 spin_lock(lock);
768 while (!list_empty(list)) {
769 bh = BH_ENTRY(list->next);
Jan Kara58ff4072006-10-17 00:10:19 -0700770 __remove_assoc_queue(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 if (buffer_dirty(bh) || buffer_locked(bh)) {
772 list_add(&bh->b_assoc_buffers, &tmp);
773 if (buffer_dirty(bh)) {
774 get_bh(bh);
775 spin_unlock(lock);
776 /*
777 * Ensure any pending I/O completes so that
778 * ll_rw_block() actually writes the current
779 * contents - it is a noop if I/O is still in
780 * flight on potentially older contents.
781 */
Jan Karaa7662232005-09-06 15:19:10 -0700782 ll_rw_block(SWRITE, 1, &bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 brelse(bh);
784 spin_lock(lock);
785 }
786 }
787 }
788
789 while (!list_empty(&tmp)) {
790 bh = BH_ENTRY(tmp.prev);
Jan Kara58ff4072006-10-17 00:10:19 -0700791 list_del_init(&bh->b_assoc_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792 get_bh(bh);
793 spin_unlock(lock);
794 wait_on_buffer(bh);
795 if (!buffer_uptodate(bh))
796 err = -EIO;
797 brelse(bh);
798 spin_lock(lock);
799 }
800
801 spin_unlock(lock);
802 err2 = osync_buffers_list(lock, list);
803 if (err)
804 return err;
805 else
806 return err2;
807}
808
809/*
810 * Invalidate any and all dirty buffers on a given inode. We are
811 * probably unmounting the fs, but that doesn't mean we have already
812 * done a sync(). Just drop the buffers from the inode list.
813 *
814 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
815 * assumes that all the buffers are against the blockdev. Not true
816 * for reiserfs.
817 */
818void invalidate_inode_buffers(struct inode *inode)
819{
820 if (inode_has_buffers(inode)) {
821 struct address_space *mapping = &inode->i_data;
822 struct list_head *list = &mapping->private_list;
823 struct address_space *buffer_mapping = mapping->assoc_mapping;
824
825 spin_lock(&buffer_mapping->private_lock);
826 while (!list_empty(list))
827 __remove_assoc_queue(BH_ENTRY(list->next));
828 spin_unlock(&buffer_mapping->private_lock);
829 }
830}
831
832/*
833 * Remove any clean buffers from the inode's buffer list. This is called
834 * when we're trying to free the inode itself. Those buffers can pin it.
835 *
836 * Returns true if all buffers were removed.
837 */
838int remove_inode_buffers(struct inode *inode)
839{
840 int ret = 1;
841
842 if (inode_has_buffers(inode)) {
843 struct address_space *mapping = &inode->i_data;
844 struct list_head *list = &mapping->private_list;
845 struct address_space *buffer_mapping = mapping->assoc_mapping;
846
847 spin_lock(&buffer_mapping->private_lock);
848 while (!list_empty(list)) {
849 struct buffer_head *bh = BH_ENTRY(list->next);
850 if (buffer_dirty(bh)) {
851 ret = 0;
852 break;
853 }
854 __remove_assoc_queue(bh);
855 }
856 spin_unlock(&buffer_mapping->private_lock);
857 }
858 return ret;
859}
860
861/*
862 * Create the appropriate buffers when given a page for data area and
863 * the size of each buffer.. Use the bh->b_this_page linked list to
864 * follow the buffers created. Return NULL if unable to create more
865 * buffers.
866 *
867 * The retry flag is used to differentiate async IO (paging, swapping)
868 * which may not fail from ordinary buffer allocations.
869 */
870struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
871 int retry)
872{
873 struct buffer_head *bh, *head;
874 long offset;
875
876try_again:
877 head = NULL;
878 offset = PAGE_SIZE;
879 while ((offset -= size) >= 0) {
880 bh = alloc_buffer_head(GFP_NOFS);
881 if (!bh)
882 goto no_grow;
883
884 bh->b_bdev = NULL;
885 bh->b_this_page = head;
886 bh->b_blocknr = -1;
887 head = bh;
888
889 bh->b_state = 0;
890 atomic_set(&bh->b_count, 0);
Chris Masonfc5cd582006-02-01 03:06:48 -0800891 bh->b_private = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892 bh->b_size = size;
893
894 /* Link the buffer to its page */
895 set_bh_page(bh, page, offset);
896
Nathan Scott01ffe332006-01-17 09:02:07 +1100897 init_buffer(bh, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700898 }
899 return head;
900/*
901 * In case anything failed, we just free everything we got.
902 */
903no_grow:
904 if (head) {
905 do {
906 bh = head;
907 head = head->b_this_page;
908 free_buffer_head(bh);
909 } while (head);
910 }
911
912 /*
913 * Return failure for non-async IO requests. Async IO requests
914 * are not allowed to fail, so we have to wait until buffer heads
915 * become available. But we don't want tasks sleeping with
916 * partially complete buffers, so all were released above.
917 */
918 if (!retry)
919 return NULL;
920
921 /* We're _really_ low on memory. Now we just
922 * wait for old buffer heads to become free due to
923 * finishing IO. Since this is an async request and
924 * the reserve list is empty, we're sure there are
925 * async buffer heads in use.
926 */
927 free_more_memory();
928 goto try_again;
929}
930EXPORT_SYMBOL_GPL(alloc_page_buffers);
931
932static inline void
933link_dev_buffers(struct page *page, struct buffer_head *head)
934{
935 struct buffer_head *bh, *tail;
936
937 bh = head;
938 do {
939 tail = bh;
940 bh = bh->b_this_page;
941 } while (bh);
942 tail->b_this_page = head;
943 attach_page_buffers(page, head);
944}
945
946/*
947 * Initialise the state of a blockdev page's buffers.
948 */
949static void
950init_page_buffers(struct page *page, struct block_device *bdev,
951 sector_t block, int size)
952{
953 struct buffer_head *head = page_buffers(page);
954 struct buffer_head *bh = head;
955 int uptodate = PageUptodate(page);
956
957 do {
958 if (!buffer_mapped(bh)) {
959 init_buffer(bh, NULL, NULL);
960 bh->b_bdev = bdev;
961 bh->b_blocknr = block;
962 if (uptodate)
963 set_buffer_uptodate(bh);
964 set_buffer_mapped(bh);
965 }
966 block++;
967 bh = bh->b_this_page;
968 } while (bh != head);
969}
970
971/*
972 * Create the page-cache page that contains the requested block.
973 *
974 * This is user purely for blockdev mappings.
975 */
976static struct page *
977grow_dev_page(struct block_device *bdev, sector_t block,
978 pgoff_t index, int size)
979{
980 struct inode *inode = bdev->bd_inode;
981 struct page *page;
982 struct buffer_head *bh;
983
Christoph Lameterea125892007-05-16 22:11:21 -0700984 page = find_or_create_page(inode->i_mapping, index,
985 mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 if (!page)
987 return NULL;
988
Eric Sesterhenne827f922006-03-26 18:24:46 +0200989 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990
991 if (page_has_buffers(page)) {
992 bh = page_buffers(page);
993 if (bh->b_size == size) {
994 init_page_buffers(page, bdev, block, size);
995 return page;
996 }
997 if (!try_to_free_buffers(page))
998 goto failed;
999 }
1000
1001 /*
1002 * Allocate some buffers for this page
1003 */
1004 bh = alloc_page_buffers(page, size, 0);
1005 if (!bh)
1006 goto failed;
1007
1008 /*
1009 * Link the page to the buffers and initialise them. Take the
1010 * lock to be atomic wrt __find_get_block(), which does not
1011 * run under the page lock.
1012 */
1013 spin_lock(&inode->i_mapping->private_lock);
1014 link_dev_buffers(page, bh);
1015 init_page_buffers(page, bdev, block, size);
1016 spin_unlock(&inode->i_mapping->private_lock);
1017 return page;
1018
1019failed:
1020 BUG();
1021 unlock_page(page);
1022 page_cache_release(page);
1023 return NULL;
1024}
1025
1026/*
1027 * Create buffers for the specified block device block's page. If
1028 * that page was dirty, the buffers are set dirty also.
1029 *
1030 * Except that's a bug. Attaching dirty buffers to a dirty
1031 * blockdev's page can result in filesystem corruption, because
1032 * some of those buffers may be aliases of filesystem data.
1033 * grow_dev_page() will go BUG() if this happens.
1034 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001035static int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001036grow_buffers(struct block_device *bdev, sector_t block, int size)
1037{
1038 struct page *page;
1039 pgoff_t index;
1040 int sizebits;
1041
1042 sizebits = -1;
1043 do {
1044 sizebits++;
1045 } while ((size << sizebits) < PAGE_SIZE);
1046
1047 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048
Andrew Mortone5657932006-10-11 01:21:46 -07001049 /*
1050 * Check for a block which wants to lie outside our maximum possible
1051 * pagecache index. (this comparison is done using sector_t types).
1052 */
1053 if (unlikely(index != block >> sizebits)) {
1054 char b[BDEVNAME_SIZE];
1055
1056 printk(KERN_ERR "%s: requested out-of-range block %llu for "
1057 "device %s\n",
1058 __FUNCTION__, (unsigned long long)block,
1059 bdevname(bdev, b));
1060 return -EIO;
1061 }
1062 block = index << sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 /* Create a page with the proper size buffers.. */
1064 page = grow_dev_page(bdev, block, index, size);
1065 if (!page)
1066 return 0;
1067 unlock_page(page);
1068 page_cache_release(page);
1069 return 1;
1070}
1071
Adrian Bunk75c96f82005-05-05 16:16:09 -07001072static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001073__getblk_slow(struct block_device *bdev, sector_t block, int size)
1074{
1075 /* Size must be multiple of hard sectorsize */
1076 if (unlikely(size & (bdev_hardsect_size(bdev)-1) ||
1077 (size < 512 || size > PAGE_SIZE))) {
1078 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1079 size);
1080 printk(KERN_ERR "hardsect size: %d\n",
1081 bdev_hardsect_size(bdev));
1082
1083 dump_stack();
1084 return NULL;
1085 }
1086
1087 for (;;) {
1088 struct buffer_head * bh;
Andrew Mortone5657932006-10-11 01:21:46 -07001089 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090
1091 bh = __find_get_block(bdev, block, size);
1092 if (bh)
1093 return bh;
1094
Andrew Mortone5657932006-10-11 01:21:46 -07001095 ret = grow_buffers(bdev, block, size);
1096 if (ret < 0)
1097 return NULL;
1098 if (ret == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099 free_more_memory();
1100 }
1101}
1102
1103/*
1104 * The relationship between dirty buffers and dirty pages:
1105 *
1106 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1107 * the page is tagged dirty in its radix tree.
1108 *
1109 * At all times, the dirtiness of the buffers represents the dirtiness of
1110 * subsections of the page. If the page has buffers, the page dirty bit is
1111 * merely a hint about the true dirty state.
1112 *
1113 * When a page is set dirty in its entirety, all its buffers are marked dirty
1114 * (if the page has buffers).
1115 *
1116 * When a buffer is marked dirty, its page is dirtied, but the page's other
1117 * buffers are not.
1118 *
1119 * Also. When blockdev buffers are explicitly read with bread(), they
1120 * individually become uptodate. But their backing page remains not
1121 * uptodate - even if all of its buffers are uptodate. A subsequent
1122 * block_read_full_page() against that page will discover all the uptodate
1123 * buffers, will set the page uptodate and will perform no I/O.
1124 */
1125
1126/**
1127 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001128 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 *
1130 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1131 * backing page dirty, then tag the page as dirty in its address_space's radix
1132 * tree and then attach the address_space's inode to its superblock's dirty
1133 * inode list.
1134 *
1135 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
1136 * mapping->tree_lock and the global inode_lock.
1137 */
1138void fastcall mark_buffer_dirty(struct buffer_head *bh)
1139{
1140 if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
1141 __set_page_dirty_nobuffers(bh->b_page);
1142}
1143
1144/*
1145 * Decrement a buffer_head's reference count. If all buffers against a page
1146 * have zero reference count, are clean and unlocked, and if the page is clean
1147 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1148 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1149 * a page but it ends up not being freed, and buffers may later be reattached).
1150 */
1151void __brelse(struct buffer_head * buf)
1152{
1153 if (atomic_read(&buf->b_count)) {
1154 put_bh(buf);
1155 return;
1156 }
1157 printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n");
1158 WARN_ON(1);
1159}
1160
1161/*
1162 * bforget() is like brelse(), except it discards any
1163 * potentially dirty data.
1164 */
1165void __bforget(struct buffer_head *bh)
1166{
1167 clear_buffer_dirty(bh);
1168 if (!list_empty(&bh->b_assoc_buffers)) {
1169 struct address_space *buffer_mapping = bh->b_page->mapping;
1170
1171 spin_lock(&buffer_mapping->private_lock);
1172 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -07001173 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 spin_unlock(&buffer_mapping->private_lock);
1175 }
1176 __brelse(bh);
1177}
1178
1179static struct buffer_head *__bread_slow(struct buffer_head *bh)
1180{
1181 lock_buffer(bh);
1182 if (buffer_uptodate(bh)) {
1183 unlock_buffer(bh);
1184 return bh;
1185 } else {
1186 get_bh(bh);
1187 bh->b_end_io = end_buffer_read_sync;
1188 submit_bh(READ, bh);
1189 wait_on_buffer(bh);
1190 if (buffer_uptodate(bh))
1191 return bh;
1192 }
1193 brelse(bh);
1194 return NULL;
1195}
1196
1197/*
1198 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1199 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1200 * refcount elevated by one when they're in an LRU. A buffer can only appear
1201 * once in a particular CPU's LRU. A single buffer can be present in multiple
1202 * CPU's LRUs at the same time.
1203 *
1204 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1205 * sb_find_get_block().
1206 *
1207 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1208 * a local interrupt disable for that.
1209 */
1210
1211#define BH_LRU_SIZE 8
1212
1213struct bh_lru {
1214 struct buffer_head *bhs[BH_LRU_SIZE];
1215};
1216
1217static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1218
1219#ifdef CONFIG_SMP
1220#define bh_lru_lock() local_irq_disable()
1221#define bh_lru_unlock() local_irq_enable()
1222#else
1223#define bh_lru_lock() preempt_disable()
1224#define bh_lru_unlock() preempt_enable()
1225#endif
1226
1227static inline void check_irqs_on(void)
1228{
1229#ifdef irqs_disabled
1230 BUG_ON(irqs_disabled());
1231#endif
1232}
1233
1234/*
1235 * The LRU management algorithm is dopey-but-simple. Sorry.
1236 */
1237static void bh_lru_install(struct buffer_head *bh)
1238{
1239 struct buffer_head *evictee = NULL;
1240 struct bh_lru *lru;
1241
1242 check_irqs_on();
1243 bh_lru_lock();
1244 lru = &__get_cpu_var(bh_lrus);
1245 if (lru->bhs[0] != bh) {
1246 struct buffer_head *bhs[BH_LRU_SIZE];
1247 int in;
1248 int out = 0;
1249
1250 get_bh(bh);
1251 bhs[out++] = bh;
1252 for (in = 0; in < BH_LRU_SIZE; in++) {
1253 struct buffer_head *bh2 = lru->bhs[in];
1254
1255 if (bh2 == bh) {
1256 __brelse(bh2);
1257 } else {
1258 if (out >= BH_LRU_SIZE) {
1259 BUG_ON(evictee != NULL);
1260 evictee = bh2;
1261 } else {
1262 bhs[out++] = bh2;
1263 }
1264 }
1265 }
1266 while (out < BH_LRU_SIZE)
1267 bhs[out++] = NULL;
1268 memcpy(lru->bhs, bhs, sizeof(bhs));
1269 }
1270 bh_lru_unlock();
1271
1272 if (evictee)
1273 __brelse(evictee);
1274}
1275
1276/*
1277 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1278 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001279static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001280lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001281{
1282 struct buffer_head *ret = NULL;
1283 struct bh_lru *lru;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001284 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001285
1286 check_irqs_on();
1287 bh_lru_lock();
1288 lru = &__get_cpu_var(bh_lrus);
1289 for (i = 0; i < BH_LRU_SIZE; i++) {
1290 struct buffer_head *bh = lru->bhs[i];
1291
1292 if (bh && bh->b_bdev == bdev &&
1293 bh->b_blocknr == block && bh->b_size == size) {
1294 if (i) {
1295 while (i) {
1296 lru->bhs[i] = lru->bhs[i - 1];
1297 i--;
1298 }
1299 lru->bhs[0] = bh;
1300 }
1301 get_bh(bh);
1302 ret = bh;
1303 break;
1304 }
1305 }
1306 bh_lru_unlock();
1307 return ret;
1308}
1309
1310/*
1311 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1312 * it in the LRU and mark it as accessed. If it is not present then return
1313 * NULL
1314 */
1315struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001316__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317{
1318 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1319
1320 if (bh == NULL) {
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001321 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001322 if (bh)
1323 bh_lru_install(bh);
1324 }
1325 if (bh)
1326 touch_buffer(bh);
1327 return bh;
1328}
1329EXPORT_SYMBOL(__find_get_block);
1330
1331/*
1332 * __getblk will locate (and, if necessary, create) the buffer_head
1333 * which corresponds to the passed block_device, block and size. The
1334 * returned buffer has its reference count incremented.
1335 *
1336 * __getblk() cannot fail - it just keeps trying. If you pass it an
1337 * illegal block number, __getblk() will happily return a buffer_head
1338 * which represents the non-existent block. Very weird.
1339 *
1340 * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1341 * attempt is failing. FIXME, perhaps?
1342 */
1343struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001344__getblk(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001345{
1346 struct buffer_head *bh = __find_get_block(bdev, block, size);
1347
1348 might_sleep();
1349 if (bh == NULL)
1350 bh = __getblk_slow(bdev, block, size);
1351 return bh;
1352}
1353EXPORT_SYMBOL(__getblk);
1354
1355/*
1356 * Do async read-ahead on a buffer..
1357 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001358void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001359{
1360 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001361 if (likely(bh)) {
1362 ll_rw_block(READA, 1, &bh);
1363 brelse(bh);
1364 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365}
1366EXPORT_SYMBOL(__breadahead);
1367
1368/**
1369 * __bread() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001370 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 * @block: number of block
1372 * @size: size (in bytes) to read
1373 *
1374 * Reads a specified block, and returns buffer head that contains it.
1375 * It returns NULL if the block was unreadable.
1376 */
1377struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001378__bread(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379{
1380 struct buffer_head *bh = __getblk(bdev, block, size);
1381
Andrew Mortona3e713b2005-10-30 15:03:15 -08001382 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 bh = __bread_slow(bh);
1384 return bh;
1385}
1386EXPORT_SYMBOL(__bread);
1387
1388/*
1389 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1390 * This doesn't race because it runs in each cpu either in irq
1391 * or with preempt disabled.
1392 */
1393static void invalidate_bh_lru(void *arg)
1394{
1395 struct bh_lru *b = &get_cpu_var(bh_lrus);
1396 int i;
1397
1398 for (i = 0; i < BH_LRU_SIZE; i++) {
1399 brelse(b->bhs[i]);
1400 b->bhs[i] = NULL;
1401 }
1402 put_cpu_var(bh_lrus);
1403}
1404
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001405void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001406{
1407 on_each_cpu(invalidate_bh_lru, NULL, 1, 1);
1408}
1409
1410void set_bh_page(struct buffer_head *bh,
1411 struct page *page, unsigned long offset)
1412{
1413 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001414 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 if (PageHighMem(page))
1416 /*
1417 * This catches illegal uses and preserves the offset:
1418 */
1419 bh->b_data = (char *)(0 + offset);
1420 else
1421 bh->b_data = page_address(page) + offset;
1422}
1423EXPORT_SYMBOL(set_bh_page);
1424
1425/*
1426 * Called when truncating a buffer on a page completely.
1427 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001428static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429{
1430 lock_buffer(bh);
1431 clear_buffer_dirty(bh);
1432 bh->b_bdev = NULL;
1433 clear_buffer_mapped(bh);
1434 clear_buffer_req(bh);
1435 clear_buffer_new(bh);
1436 clear_buffer_delay(bh);
David Chinner33a266d2007-02-12 00:51:41 -08001437 clear_buffer_unwritten(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 unlock_buffer(bh);
1439}
1440
1441/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 * block_invalidatepage - invalidate part of all of a buffer-backed page
1443 *
1444 * @page: the page which is affected
1445 * @offset: the index of the truncation point
1446 *
1447 * block_invalidatepage() is called when all or part of the page has become
1448 * invalidatedby a truncate operation.
1449 *
1450 * block_invalidatepage() does not have to release all buffers, but it must
1451 * ensure that no dirty buffer is left outside @offset and that no I/O
1452 * is underway against any of the blocks which are outside the truncation
1453 * point. Because the caller is about to free (and possibly reuse) those
1454 * blocks on-disk.
1455 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001456void block_invalidatepage(struct page *page, unsigned long offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001457{
1458 struct buffer_head *head, *bh, *next;
1459 unsigned int curr_off = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460
1461 BUG_ON(!PageLocked(page));
1462 if (!page_has_buffers(page))
1463 goto out;
1464
1465 head = page_buffers(page);
1466 bh = head;
1467 do {
1468 unsigned int next_off = curr_off + bh->b_size;
1469 next = bh->b_this_page;
1470
1471 /*
1472 * is this block fully invalidated?
1473 */
1474 if (offset <= curr_off)
1475 discard_buffer(bh);
1476 curr_off = next_off;
1477 bh = next;
1478 } while (bh != head);
1479
1480 /*
1481 * We release buffers only if the entire page is being invalidated.
1482 * The get_block cached value has been unconditionally invalidated,
1483 * so real IO is not possible anymore.
1484 */
1485 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001486 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001488 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489}
1490EXPORT_SYMBOL(block_invalidatepage);
1491
1492/*
1493 * We attach and possibly dirty the buffers atomically wrt
1494 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1495 * is already excluded via the page lock.
1496 */
1497void create_empty_buffers(struct page *page,
1498 unsigned long blocksize, unsigned long b_state)
1499{
1500 struct buffer_head *bh, *head, *tail;
1501
1502 head = alloc_page_buffers(page, blocksize, 1);
1503 bh = head;
1504 do {
1505 bh->b_state |= b_state;
1506 tail = bh;
1507 bh = bh->b_this_page;
1508 } while (bh);
1509 tail->b_this_page = head;
1510
1511 spin_lock(&page->mapping->private_lock);
1512 if (PageUptodate(page) || PageDirty(page)) {
1513 bh = head;
1514 do {
1515 if (PageDirty(page))
1516 set_buffer_dirty(bh);
1517 if (PageUptodate(page))
1518 set_buffer_uptodate(bh);
1519 bh = bh->b_this_page;
1520 } while (bh != head);
1521 }
1522 attach_page_buffers(page, head);
1523 spin_unlock(&page->mapping->private_lock);
1524}
1525EXPORT_SYMBOL(create_empty_buffers);
1526
1527/*
1528 * We are taking a block for data and we don't want any output from any
1529 * buffer-cache aliases starting from return from that function and
1530 * until the moment when something will explicitly mark the buffer
1531 * dirty (hopefully that will not happen until we will free that block ;-)
1532 * We don't even need to mark it not-uptodate - nobody can expect
1533 * anything from a newly allocated buffer anyway. We used to used
1534 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1535 * don't want to mark the alias unmapped, for example - it would confuse
1536 * anyone who might pick it with bread() afterwards...
1537 *
1538 * Also.. Note that bforget() doesn't lock the buffer. So there can
1539 * be writeout I/O going on against recently-freed buffers. We don't
1540 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1541 * only if we really need to. That happens here.
1542 */
1543void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1544{
1545 struct buffer_head *old_bh;
1546
1547 might_sleep();
1548
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001549 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 if (old_bh) {
1551 clear_buffer_dirty(old_bh);
1552 wait_on_buffer(old_bh);
1553 clear_buffer_req(old_bh);
1554 __brelse(old_bh);
1555 }
1556}
1557EXPORT_SYMBOL(unmap_underlying_metadata);
1558
1559/*
1560 * NOTE! All mapped/uptodate combinations are valid:
1561 *
1562 * Mapped Uptodate Meaning
1563 *
1564 * No No "unknown" - must do get_block()
1565 * No Yes "hole" - zero-filled
1566 * Yes No "allocated" - allocated on disk, not read in
1567 * Yes Yes "valid" - allocated and up-to-date in memory.
1568 *
1569 * "Dirty" is valid only with the last case (mapped+uptodate).
1570 */
1571
1572/*
1573 * While block_write_full_page is writing back the dirty buffers under
1574 * the page lock, whoever dirtied the buffers may decide to clean them
1575 * again at any time. We handle that by only looking at the buffer
1576 * state inside lock_buffer().
1577 *
1578 * If block_write_full_page() is called for regular writeback
1579 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1580 * locked buffer. This only can happen if someone has written the buffer
1581 * directly, with submit_bh(). At the address_space level PageWriteback
1582 * prevents this contention from occurring.
1583 */
1584static int __block_write_full_page(struct inode *inode, struct page *page,
1585 get_block_t *get_block, struct writeback_control *wbc)
1586{
1587 int err;
1588 sector_t block;
1589 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001590 struct buffer_head *bh, *head;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001591 const unsigned blocksize = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 int nr_underway = 0;
1593
1594 BUG_ON(!PageLocked(page));
1595
1596 last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
1597
1598 if (!page_has_buffers(page)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001599 create_empty_buffers(page, blocksize,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600 (1 << BH_Dirty)|(1 << BH_Uptodate));
1601 }
1602
1603 /*
1604 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1605 * here, and the (potentially unmapped) buffers may become dirty at
1606 * any time. If a buffer becomes dirty here after we've inspected it
1607 * then we just miss that fact, and the page stays dirty.
1608 *
1609 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1610 * handle that here by just cleaning them.
1611 */
1612
Andrew Morton54b21a72006-01-08 01:03:05 -08001613 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 head = page_buffers(page);
1615 bh = head;
1616
1617 /*
1618 * Get all the dirty buffers mapped to disk addresses and
1619 * handle any aliases from the underlying blockdev's mapping.
1620 */
1621 do {
1622 if (block > last_block) {
1623 /*
1624 * mapped buffers outside i_size will occur, because
1625 * this page can be outside i_size when there is a
1626 * truncate in progress.
1627 */
1628 /*
1629 * The buffer was zeroed by block_write_full_page()
1630 */
1631 clear_buffer_dirty(bh);
1632 set_buffer_uptodate(bh);
1633 } else if (!buffer_mapped(bh) && buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001634 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 err = get_block(inode, block, bh, 1);
1636 if (err)
1637 goto recover;
1638 if (buffer_new(bh)) {
1639 /* blockdev mappings never come here */
1640 clear_buffer_new(bh);
1641 unmap_underlying_metadata(bh->b_bdev,
1642 bh->b_blocknr);
1643 }
1644 }
1645 bh = bh->b_this_page;
1646 block++;
1647 } while (bh != head);
1648
1649 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650 if (!buffer_mapped(bh))
1651 continue;
1652 /*
1653 * If it's a fully non-blocking write attempt and we cannot
1654 * lock the buffer then redirty the page. Note that this can
1655 * potentially cause a busy-wait loop from pdflush and kswapd
1656 * activity, but those code paths have their own higher-level
1657 * throttling.
1658 */
1659 if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
1660 lock_buffer(bh);
1661 } else if (test_set_buffer_locked(bh)) {
1662 redirty_page_for_writepage(wbc, page);
1663 continue;
1664 }
1665 if (test_clear_buffer_dirty(bh)) {
1666 mark_buffer_async_write(bh);
1667 } else {
1668 unlock_buffer(bh);
1669 }
1670 } while ((bh = bh->b_this_page) != head);
1671
1672 /*
1673 * The page and its buffers are protected by PageWriteback(), so we can
1674 * drop the bh refcounts early.
1675 */
1676 BUG_ON(PageWriteback(page));
1677 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678
1679 do {
1680 struct buffer_head *next = bh->b_this_page;
1681 if (buffer_async_write(bh)) {
1682 submit_bh(WRITE, bh);
1683 nr_underway++;
1684 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 bh = next;
1686 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001687 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688
1689 err = 0;
1690done:
1691 if (nr_underway == 0) {
1692 /*
1693 * The page was marked dirty, but the buffers were
1694 * clean. Someone wrote them back by hand with
1695 * ll_rw_block/submit_bh. A rare case.
1696 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001698
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 /*
1700 * The page and buffer_heads can be released at any time from
1701 * here on.
1702 */
1703 wbc->pages_skipped++; /* We didn't write this page */
1704 }
1705 return err;
1706
1707recover:
1708 /*
1709 * ENOSPC, or some other error. We may already have added some
1710 * blocks to the file, so we need to write these out to avoid
1711 * exposing stale data.
1712 * The page is currently locked and not marked for writeback
1713 */
1714 bh = head;
1715 /* Recovery: lock and submit the mapped buffers */
1716 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001717 if (buffer_mapped(bh) && buffer_dirty(bh)) {
1718 lock_buffer(bh);
1719 mark_buffer_async_write(bh);
1720 } else {
1721 /*
1722 * The buffer may have been set dirty during
1723 * attachment to a dirty page.
1724 */
1725 clear_buffer_dirty(bh);
1726 }
1727 } while ((bh = bh->b_this_page) != head);
1728 SetPageError(page);
1729 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001730 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001731 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 do {
1733 struct buffer_head *next = bh->b_this_page;
1734 if (buffer_async_write(bh)) {
1735 clear_buffer_dirty(bh);
1736 submit_bh(WRITE, bh);
1737 nr_underway++;
1738 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 bh = next;
1740 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001741 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 goto done;
1743}
1744
1745static int __block_prepare_write(struct inode *inode, struct page *page,
1746 unsigned from, unsigned to, get_block_t *get_block)
1747{
1748 unsigned block_start, block_end;
1749 sector_t block;
1750 int err = 0;
1751 unsigned blocksize, bbits;
1752 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1753
1754 BUG_ON(!PageLocked(page));
1755 BUG_ON(from > PAGE_CACHE_SIZE);
1756 BUG_ON(to > PAGE_CACHE_SIZE);
1757 BUG_ON(from > to);
1758
1759 blocksize = 1 << inode->i_blkbits;
1760 if (!page_has_buffers(page))
1761 create_empty_buffers(page, blocksize, 0);
1762 head = page_buffers(page);
1763
1764 bbits = inode->i_blkbits;
1765 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1766
1767 for(bh = head, block_start = 0; bh != head || !block_start;
1768 block++, block_start=block_end, bh = bh->b_this_page) {
1769 block_end = block_start + blocksize;
1770 if (block_end <= from || block_start >= to) {
1771 if (PageUptodate(page)) {
1772 if (!buffer_uptodate(bh))
1773 set_buffer_uptodate(bh);
1774 }
1775 continue;
1776 }
1777 if (buffer_new(bh))
1778 clear_buffer_new(bh);
1779 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001780 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781 err = get_block(inode, block, bh, 1);
1782 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001783 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785 unmap_underlying_metadata(bh->b_bdev,
1786 bh->b_blocknr);
1787 if (PageUptodate(page)) {
1788 set_buffer_uptodate(bh);
1789 continue;
1790 }
1791 if (block_end > to || block_start < from) {
1792 void *kaddr;
1793
1794 kaddr = kmap_atomic(page, KM_USER0);
1795 if (block_end > to)
1796 memset(kaddr+to, 0,
1797 block_end-to);
1798 if (block_start < from)
1799 memset(kaddr+block_start,
1800 0, from-block_start);
1801 flush_dcache_page(page);
1802 kunmap_atomic(kaddr, KM_USER0);
1803 }
1804 continue;
1805 }
1806 }
1807 if (PageUptodate(page)) {
1808 if (!buffer_uptodate(bh))
1809 set_buffer_uptodate(bh);
1810 continue;
1811 }
1812 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08001813 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 (block_start < from || block_end > to)) {
1815 ll_rw_block(READ, 1, &bh);
1816 *wait_bh++=bh;
1817 }
1818 }
1819 /*
1820 * If we issued read requests - let them complete.
1821 */
1822 while(wait_bh > wait) {
1823 wait_on_buffer(*--wait_bh);
1824 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001825 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 }
Anton Altaparmakov152becd2005-06-23 00:10:21 -07001827 if (!err) {
1828 bh = head;
1829 do {
1830 if (buffer_new(bh))
1831 clear_buffer_new(bh);
1832 } while ((bh = bh->b_this_page) != head);
1833 return 0;
1834 }
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001835 /* Error case: */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 /*
1837 * Zero out any newly allocated blocks to avoid exposing stale
1838 * data. If BH_New is set, we know that the block was newly
1839 * allocated in the above loop.
1840 */
1841 bh = head;
1842 block_start = 0;
1843 do {
1844 block_end = block_start+blocksize;
1845 if (block_end <= from)
1846 goto next_bh;
1847 if (block_start >= to)
1848 break;
1849 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850 clear_buffer_new(bh);
Nate Diller01f27052007-05-09 02:35:07 -07001851 zero_user_page(page, block_start, bh->b_size, KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852 set_buffer_uptodate(bh);
1853 mark_buffer_dirty(bh);
1854 }
1855next_bh:
1856 block_start = block_end;
1857 bh = bh->b_this_page;
1858 } while (bh != head);
1859 return err;
1860}
1861
1862static int __block_commit_write(struct inode *inode, struct page *page,
1863 unsigned from, unsigned to)
1864{
1865 unsigned block_start, block_end;
1866 int partial = 0;
1867 unsigned blocksize;
1868 struct buffer_head *bh, *head;
1869
1870 blocksize = 1 << inode->i_blkbits;
1871
1872 for(bh = head = page_buffers(page), block_start = 0;
1873 bh != head || !block_start;
1874 block_start=block_end, bh = bh->b_this_page) {
1875 block_end = block_start + blocksize;
1876 if (block_end <= from || block_start >= to) {
1877 if (!buffer_uptodate(bh))
1878 partial = 1;
1879 } else {
1880 set_buffer_uptodate(bh);
1881 mark_buffer_dirty(bh);
1882 }
1883 }
1884
1885 /*
1886 * If this is a partial write which happened to make all buffers
1887 * uptodate then we can optimize away a bogus readpage() for
1888 * the next read(). Here we 'discover' whether the page went
1889 * uptodate as a result of this (potentially partial) write.
1890 */
1891 if (!partial)
1892 SetPageUptodate(page);
1893 return 0;
1894}
1895
1896/*
1897 * Generic "read page" function for block devices that have the normal
1898 * get_block functionality. This is most of the block device filesystems.
1899 * Reads the page asynchronously --- the unlock_buffer() and
1900 * set/clear_buffer_uptodate() functions propagate buffer state into the
1901 * page struct once IO has completed.
1902 */
1903int block_read_full_page(struct page *page, get_block_t *get_block)
1904{
1905 struct inode *inode = page->mapping->host;
1906 sector_t iblock, lblock;
1907 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
1908 unsigned int blocksize;
1909 int nr, i;
1910 int fully_mapped = 1;
1911
Matt Mackallcd7619d2005-05-01 08:59:01 -07001912 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913 blocksize = 1 << inode->i_blkbits;
1914 if (!page_has_buffers(page))
1915 create_empty_buffers(page, blocksize, 0);
1916 head = page_buffers(page);
1917
1918 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
1919 lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
1920 bh = head;
1921 nr = 0;
1922 i = 0;
1923
1924 do {
1925 if (buffer_uptodate(bh))
1926 continue;
1927
1928 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07001929 int err = 0;
1930
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931 fully_mapped = 0;
1932 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001933 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07001934 err = get_block(inode, iblock, bh, 0);
1935 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936 SetPageError(page);
1937 }
1938 if (!buffer_mapped(bh)) {
Nate Diller01f27052007-05-09 02:35:07 -07001939 zero_user_page(page, i * blocksize, blocksize,
1940 KM_USER0);
Andrew Mortonc64610b2005-05-16 21:53:49 -07001941 if (!err)
1942 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 continue;
1944 }
1945 /*
1946 * get_block() might have updated the buffer
1947 * synchronously
1948 */
1949 if (buffer_uptodate(bh))
1950 continue;
1951 }
1952 arr[nr++] = bh;
1953 } while (i++, iblock++, (bh = bh->b_this_page) != head);
1954
1955 if (fully_mapped)
1956 SetPageMappedToDisk(page);
1957
1958 if (!nr) {
1959 /*
1960 * All buffers are uptodate - we can set the page uptodate
1961 * as well. But not if get_block() returned an error.
1962 */
1963 if (!PageError(page))
1964 SetPageUptodate(page);
1965 unlock_page(page);
1966 return 0;
1967 }
1968
1969 /* Stage two: lock the buffers */
1970 for (i = 0; i < nr; i++) {
1971 bh = arr[i];
1972 lock_buffer(bh);
1973 mark_buffer_async_read(bh);
1974 }
1975
1976 /*
1977 * Stage 3: start the IO. Check for uptodateness
1978 * inside the buffer lock in case another process reading
1979 * the underlying blockdev brought it uptodate (the sct fix).
1980 */
1981 for (i = 0; i < nr; i++) {
1982 bh = arr[i];
1983 if (buffer_uptodate(bh))
1984 end_buffer_async_read(bh, 1);
1985 else
1986 submit_bh(READ, bh);
1987 }
1988 return 0;
1989}
1990
1991/* utility function for filesystems that need to do work on expanding
1992 * truncates. Uses prepare/commit_write to allow the filesystem to
1993 * deal with the hole.
1994 */
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08001995static int __generic_cont_expand(struct inode *inode, loff_t size,
1996 pgoff_t index, unsigned int offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997{
1998 struct address_space *mapping = inode->i_mapping;
1999 struct page *page;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002000 unsigned long limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001 int err;
2002
2003 err = -EFBIG;
2004 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
2005 if (limit != RLIM_INFINITY && size > (loff_t)limit) {
2006 send_sig(SIGXFSZ, current, 0);
2007 goto out;
2008 }
2009 if (size > inode->i_sb->s_maxbytes)
2010 goto out;
2011
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012 err = -ENOMEM;
2013 page = grab_cache_page(mapping, index);
2014 if (!page)
2015 goto out;
2016 err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002017 if (err) {
2018 /*
2019 * ->prepare_write() may have instantiated a few blocks
2020 * outside i_size. Trim these off again.
2021 */
2022 unlock_page(page);
2023 page_cache_release(page);
2024 vmtruncate(inode, inode->i_size);
2025 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026 }
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002027
2028 err = mapping->a_ops->commit_write(NULL, page, offset, offset);
2029
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 unlock_page(page);
2031 page_cache_release(page);
2032 if (err > 0)
2033 err = 0;
2034out:
2035 return err;
2036}
2037
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002038int generic_cont_expand(struct inode *inode, loff_t size)
2039{
2040 pgoff_t index;
2041 unsigned int offset;
2042
2043 offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
2044
2045 /* ugh. in prepare/commit_write, if from==to==start of block, we
2046 ** skip the prepare. make sure we never send an offset for the start
2047 ** of a block
2048 */
2049 if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
2050 /* caller must handle this extra byte. */
2051 offset++;
2052 }
2053 index = size >> PAGE_CACHE_SHIFT;
2054
2055 return __generic_cont_expand(inode, size, index, offset);
2056}
2057
2058int generic_cont_expand_simple(struct inode *inode, loff_t size)
2059{
2060 loff_t pos = size - 1;
2061 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
2062 unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
2063
2064 /* prepare/commit_write can handle even if from==to==start of block. */
2065 return __generic_cont_expand(inode, size, index, offset);
2066}
2067
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068/*
2069 * For moronic filesystems that do not allow holes in file.
2070 * We may have to extend the file.
2071 */
2072
2073int cont_prepare_write(struct page *page, unsigned offset,
2074 unsigned to, get_block_t *get_block, loff_t *bytes)
2075{
2076 struct address_space *mapping = page->mapping;
2077 struct inode *inode = mapping->host;
2078 struct page *new_page;
2079 pgoff_t pgpos;
2080 long status;
2081 unsigned zerofrom;
2082 unsigned blocksize = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002083
2084 while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
2085 status = -ENOMEM;
2086 new_page = grab_cache_page(mapping, pgpos);
2087 if (!new_page)
2088 goto out;
2089 /* we might sleep */
2090 if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
2091 unlock_page(new_page);
2092 page_cache_release(new_page);
2093 continue;
2094 }
2095 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2096 if (zerofrom & (blocksize-1)) {
2097 *bytes |= (blocksize-1);
2098 (*bytes)++;
2099 }
2100 status = __block_prepare_write(inode, new_page, zerofrom,
2101 PAGE_CACHE_SIZE, get_block);
2102 if (status)
2103 goto out_unmap;
OGAWA Hirofumiff1be9a2007-05-20 23:39:40 +09002104 zero_user_page(new_page, zerofrom, PAGE_CACHE_SIZE - zerofrom,
Nate Diller01f27052007-05-09 02:35:07 -07002105 KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002106 generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
2107 unlock_page(new_page);
2108 page_cache_release(new_page);
2109 }
2110
2111 if (page->index < pgpos) {
2112 /* completely inside the area */
2113 zerofrom = offset;
2114 } else {
2115 /* page covers the boundary, find the boundary offset */
2116 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2117
2118 /* if we will expand the thing last block will be filled */
2119 if (to > zerofrom && (zerofrom & (blocksize-1))) {
2120 *bytes |= (blocksize-1);
2121 (*bytes)++;
2122 }
2123
2124 /* starting below the boundary? Nothing to zero out */
2125 if (offset <= zerofrom)
2126 zerofrom = offset;
2127 }
2128 status = __block_prepare_write(inode, page, zerofrom, to, get_block);
2129 if (status)
2130 goto out1;
2131 if (zerofrom < offset) {
Nate Diller01f27052007-05-09 02:35:07 -07002132 zero_user_page(page, zerofrom, offset - zerofrom, KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 __block_commit_write(inode, page, zerofrom, offset);
2134 }
2135 return 0;
2136out1:
2137 ClearPageUptodate(page);
2138 return status;
2139
2140out_unmap:
2141 ClearPageUptodate(new_page);
2142 unlock_page(new_page);
2143 page_cache_release(new_page);
2144out:
2145 return status;
2146}
2147
2148int block_prepare_write(struct page *page, unsigned from, unsigned to,
2149 get_block_t *get_block)
2150{
2151 struct inode *inode = page->mapping->host;
2152 int err = __block_prepare_write(inode, page, from, to, get_block);
2153 if (err)
2154 ClearPageUptodate(page);
2155 return err;
2156}
2157
2158int block_commit_write(struct page *page, unsigned from, unsigned to)
2159{
2160 struct inode *inode = page->mapping->host;
2161 __block_commit_write(inode,page,from,to);
2162 return 0;
2163}
2164
2165int generic_commit_write(struct file *file, struct page *page,
2166 unsigned from, unsigned to)
2167{
2168 struct inode *inode = page->mapping->host;
2169 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2170 __block_commit_write(inode,page,from,to);
2171 /*
2172 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002173 * cannot change under us because we hold i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 */
2175 if (pos > inode->i_size) {
2176 i_size_write(inode, pos);
2177 mark_inode_dirty(inode);
2178 }
2179 return 0;
2180}
2181
2182
2183/*
2184 * nobh_prepare_write()'s prereads are special: the buffer_heads are freed
2185 * immediately, while under the page lock. So it needs a special end_io
2186 * handler which does not touch the bh after unlocking it.
2187 *
2188 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
2189 * a race there is benign: unlock_buffer() only use the bh's address for
2190 * hashing after unlocking the buffer, so it doesn't actually touch the bh
2191 * itself.
2192 */
2193static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2194{
2195 if (uptodate) {
2196 set_buffer_uptodate(bh);
2197 } else {
2198 /* This happens, due to failed READA attempts. */
2199 clear_buffer_uptodate(bh);
2200 }
2201 unlock_buffer(bh);
2202}
2203
2204/*
2205 * On entry, the page is fully not uptodate.
2206 * On exit the page is fully uptodate in the areas outside (from,to)
2207 */
2208int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
2209 get_block_t *get_block)
2210{
2211 struct inode *inode = page->mapping->host;
2212 const unsigned blkbits = inode->i_blkbits;
2213 const unsigned blocksize = 1 << blkbits;
2214 struct buffer_head map_bh;
2215 struct buffer_head *read_bh[MAX_BUF_PER_PAGE];
2216 unsigned block_in_page;
2217 unsigned block_start;
2218 sector_t block_in_file;
2219 char *kaddr;
2220 int nr_reads = 0;
2221 int i;
2222 int ret = 0;
2223 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224
2225 if (PageMappedToDisk(page))
2226 return 0;
2227
2228 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
2229 map_bh.b_page = page;
2230
2231 /*
2232 * We loop across all blocks in the page, whether or not they are
2233 * part of the affected region. This is so we can discover if the
2234 * page is fully mapped-to-disk.
2235 */
2236 for (block_start = 0, block_in_page = 0;
2237 block_start < PAGE_CACHE_SIZE;
2238 block_in_page++, block_start += blocksize) {
2239 unsigned block_end = block_start + blocksize;
2240 int create;
2241
2242 map_bh.b_state = 0;
2243 create = 1;
2244 if (block_start >= to)
2245 create = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002246 map_bh.b_size = blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247 ret = get_block(inode, block_in_file + block_in_page,
2248 &map_bh, create);
2249 if (ret)
2250 goto failed;
2251 if (!buffer_mapped(&map_bh))
2252 is_mapped_to_disk = 0;
2253 if (buffer_new(&map_bh))
2254 unmap_underlying_metadata(map_bh.b_bdev,
2255 map_bh.b_blocknr);
2256 if (PageUptodate(page))
2257 continue;
2258 if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) {
2259 kaddr = kmap_atomic(page, KM_USER0);
Nick Piggin22c8ca72007-02-20 13:58:09 -08002260 if (block_start < from)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 memset(kaddr+block_start, 0, from-block_start);
Nick Piggin22c8ca72007-02-20 13:58:09 -08002262 if (block_end > to)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 memset(kaddr + to, 0, block_end - to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264 flush_dcache_page(page);
2265 kunmap_atomic(kaddr, KM_USER0);
2266 continue;
2267 }
2268 if (buffer_uptodate(&map_bh))
2269 continue; /* reiserfs does this */
2270 if (block_start < from || block_end > to) {
2271 struct buffer_head *bh = alloc_buffer_head(GFP_NOFS);
2272
2273 if (!bh) {
2274 ret = -ENOMEM;
2275 goto failed;
2276 }
2277 bh->b_state = map_bh.b_state;
2278 atomic_set(&bh->b_count, 0);
2279 bh->b_this_page = NULL;
2280 bh->b_page = page;
2281 bh->b_blocknr = map_bh.b_blocknr;
2282 bh->b_size = blocksize;
2283 bh->b_data = (char *)(long)block_start;
2284 bh->b_bdev = map_bh.b_bdev;
2285 bh->b_private = NULL;
2286 read_bh[nr_reads++] = bh;
2287 }
2288 }
2289
2290 if (nr_reads) {
2291 struct buffer_head *bh;
2292
2293 /*
2294 * The page is locked, so these buffers are protected from
2295 * any VM or truncate activity. Hence we don't need to care
2296 * for the buffer_head refcounts.
2297 */
2298 for (i = 0; i < nr_reads; i++) {
2299 bh = read_bh[i];
2300 lock_buffer(bh);
2301 bh->b_end_io = end_buffer_read_nobh;
2302 submit_bh(READ, bh);
2303 }
2304 for (i = 0; i < nr_reads; i++) {
2305 bh = read_bh[i];
2306 wait_on_buffer(bh);
2307 if (!buffer_uptodate(bh))
2308 ret = -EIO;
2309 free_buffer_head(bh);
2310 read_bh[i] = NULL;
2311 }
2312 if (ret)
2313 goto failed;
2314 }
2315
2316 if (is_mapped_to_disk)
2317 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318
2319 return 0;
2320
2321failed:
2322 for (i = 0; i < nr_reads; i++) {
2323 if (read_bh[i])
2324 free_buffer_head(read_bh[i]);
2325 }
2326
2327 /*
2328 * Error recovery is pretty slack. Clear the page and mark it dirty
2329 * so we'll later zero out any blocks which _were_ allocated.
2330 */
Nate Diller01f27052007-05-09 02:35:07 -07002331 zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 SetPageUptodate(page);
2333 set_page_dirty(page);
2334 return ret;
2335}
2336EXPORT_SYMBOL(nobh_prepare_write);
2337
Dave Kleikamp57bf63d2007-03-06 01:42:12 -08002338/*
2339 * Make sure any changes to nobh_commit_write() are reflected in
2340 * nobh_truncate_page(), since it doesn't call commit_write().
2341 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342int nobh_commit_write(struct file *file, struct page *page,
2343 unsigned from, unsigned to)
2344{
2345 struct inode *inode = page->mapping->host;
2346 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2347
Nick Piggin22c8ca72007-02-20 13:58:09 -08002348 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349 set_page_dirty(page);
2350 if (pos > inode->i_size) {
2351 i_size_write(inode, pos);
2352 mark_inode_dirty(inode);
2353 }
2354 return 0;
2355}
2356EXPORT_SYMBOL(nobh_commit_write);
2357
2358/*
2359 * nobh_writepage() - based on block_full_write_page() except
2360 * that it tries to operate without attaching bufferheads to
2361 * the page.
2362 */
2363int nobh_writepage(struct page *page, get_block_t *get_block,
2364 struct writeback_control *wbc)
2365{
2366 struct inode * const inode = page->mapping->host;
2367 loff_t i_size = i_size_read(inode);
2368 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2369 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370 int ret;
2371
2372 /* Is the page fully inside i_size? */
2373 if (page->index < end_index)
2374 goto out;
2375
2376 /* Is the page fully outside i_size? (truncate in progress) */
2377 offset = i_size & (PAGE_CACHE_SIZE-1);
2378 if (page->index >= end_index+1 || !offset) {
2379 /*
2380 * The page may have dirty, unmapped buffers. For example,
2381 * they may have been added in ext3_writepage(). Make them
2382 * freeable here, so the page does not leak.
2383 */
2384#if 0
2385 /* Not really sure about this - do we need this ? */
2386 if (page->mapping->a_ops->invalidatepage)
2387 page->mapping->a_ops->invalidatepage(page, offset);
2388#endif
2389 unlock_page(page);
2390 return 0; /* don't care */
2391 }
2392
2393 /*
2394 * The page straddles i_size. It must be zeroed out on each and every
2395 * writepage invocation because it may be mmapped. "A file is mapped
2396 * in multiples of the page size. For a file that is not a multiple of
2397 * the page size, the remaining memory is zeroed when mapped, and
2398 * writes to that region are not written out to the file."
2399 */
Nate Diller01f27052007-05-09 02:35:07 -07002400 zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002401out:
2402 ret = mpage_writepage(page, get_block, wbc);
2403 if (ret == -EAGAIN)
2404 ret = __block_write_full_page(inode, page, get_block, wbc);
2405 return ret;
2406}
2407EXPORT_SYMBOL(nobh_writepage);
2408
2409/*
2410 * This function assumes that ->prepare_write() uses nobh_prepare_write().
2411 */
2412int nobh_truncate_page(struct address_space *mapping, loff_t from)
2413{
2414 struct inode *inode = mapping->host;
2415 unsigned blocksize = 1 << inode->i_blkbits;
2416 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2417 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2418 unsigned to;
2419 struct page *page;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002420 const struct address_space_operations *a_ops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002421 int ret = 0;
2422
2423 if ((offset & (blocksize - 1)) == 0)
2424 goto out;
2425
2426 ret = -ENOMEM;
2427 page = grab_cache_page(mapping, index);
2428 if (!page)
2429 goto out;
2430
2431 to = (offset + blocksize) & ~(blocksize - 1);
2432 ret = a_ops->prepare_write(NULL, page, offset, to);
2433 if (ret == 0) {
Nate Diller01f27052007-05-09 02:35:07 -07002434 zero_user_page(page, offset, PAGE_CACHE_SIZE - offset,
2435 KM_USER0);
Dave Kleikamp57bf63d2007-03-06 01:42:12 -08002436 /*
2437 * It would be more correct to call aops->commit_write()
2438 * here, but this is more efficient.
2439 */
2440 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002441 set_page_dirty(page);
2442 }
2443 unlock_page(page);
2444 page_cache_release(page);
2445out:
2446 return ret;
2447}
2448EXPORT_SYMBOL(nobh_truncate_page);
2449
2450int block_truncate_page(struct address_space *mapping,
2451 loff_t from, get_block_t *get_block)
2452{
2453 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2454 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2455 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002456 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002457 unsigned length, pos;
2458 struct inode *inode = mapping->host;
2459 struct page *page;
2460 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002461 int err;
2462
2463 blocksize = 1 << inode->i_blkbits;
2464 length = offset & (blocksize - 1);
2465
2466 /* Block boundary? Nothing to do */
2467 if (!length)
2468 return 0;
2469
2470 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002471 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002472
2473 page = grab_cache_page(mapping, index);
2474 err = -ENOMEM;
2475 if (!page)
2476 goto out;
2477
2478 if (!page_has_buffers(page))
2479 create_empty_buffers(page, blocksize, 0);
2480
2481 /* Find the buffer that contains "offset" */
2482 bh = page_buffers(page);
2483 pos = blocksize;
2484 while (offset >= pos) {
2485 bh = bh->b_this_page;
2486 iblock++;
2487 pos += blocksize;
2488 }
2489
2490 err = 0;
2491 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002492 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002493 err = get_block(inode, iblock, bh, 0);
2494 if (err)
2495 goto unlock;
2496 /* unmapped? It's a hole - nothing to do */
2497 if (!buffer_mapped(bh))
2498 goto unlock;
2499 }
2500
2501 /* Ok, it's mapped. Make sure it's up-to-date */
2502 if (PageUptodate(page))
2503 set_buffer_uptodate(bh);
2504
David Chinner33a266d2007-02-12 00:51:41 -08002505 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002506 err = -EIO;
2507 ll_rw_block(READ, 1, &bh);
2508 wait_on_buffer(bh);
2509 /* Uhhuh. Read error. Complain and punt. */
2510 if (!buffer_uptodate(bh))
2511 goto unlock;
2512 }
2513
Nate Diller01f27052007-05-09 02:35:07 -07002514 zero_user_page(page, offset, length, KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515 mark_buffer_dirty(bh);
2516 err = 0;
2517
2518unlock:
2519 unlock_page(page);
2520 page_cache_release(page);
2521out:
2522 return err;
2523}
2524
2525/*
2526 * The generic ->writepage function for buffer-backed address_spaces
2527 */
2528int block_write_full_page(struct page *page, get_block_t *get_block,
2529 struct writeback_control *wbc)
2530{
2531 struct inode * const inode = page->mapping->host;
2532 loff_t i_size = i_size_read(inode);
2533 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2534 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002535
2536 /* Is the page fully inside i_size? */
2537 if (page->index < end_index)
2538 return __block_write_full_page(inode, page, get_block, wbc);
2539
2540 /* Is the page fully outside i_size? (truncate in progress) */
2541 offset = i_size & (PAGE_CACHE_SIZE-1);
2542 if (page->index >= end_index+1 || !offset) {
2543 /*
2544 * The page may have dirty, unmapped buffers. For example,
2545 * they may have been added in ext3_writepage(). Make them
2546 * freeable here, so the page does not leak.
2547 */
Jan Karaaaa40592005-10-30 15:00:16 -08002548 do_invalidatepage(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002549 unlock_page(page);
2550 return 0; /* don't care */
2551 }
2552
2553 /*
2554 * The page straddles i_size. It must be zeroed out on each and every
2555 * writepage invokation because it may be mmapped. "A file is mapped
2556 * in multiples of the page size. For a file that is not a multiple of
2557 * the page size, the remaining memory is zeroed when mapped, and
2558 * writes to that region are not written out to the file."
2559 */
Nate Diller01f27052007-05-09 02:35:07 -07002560 zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002561 return __block_write_full_page(inode, page, get_block, wbc);
2562}
2563
2564sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2565 get_block_t *get_block)
2566{
2567 struct buffer_head tmp;
2568 struct inode *inode = mapping->host;
2569 tmp.b_state = 0;
2570 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002571 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002572 get_block(inode, block, &tmp, 0);
2573 return tmp.b_blocknr;
2574}
2575
2576static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err)
2577{
2578 struct buffer_head *bh = bio->bi_private;
2579
2580 if (bio->bi_size)
2581 return 1;
2582
2583 if (err == -EOPNOTSUPP) {
2584 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
2585 set_bit(BH_Eopnotsupp, &bh->b_state);
2586 }
2587
2588 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2589 bio_put(bio);
2590 return 0;
2591}
2592
2593int submit_bh(int rw, struct buffer_head * bh)
2594{
2595 struct bio *bio;
2596 int ret = 0;
2597
2598 BUG_ON(!buffer_locked(bh));
2599 BUG_ON(!buffer_mapped(bh));
2600 BUG_ON(!bh->b_end_io);
2601
2602 if (buffer_ordered(bh) && (rw == WRITE))
2603 rw = WRITE_BARRIER;
2604
2605 /*
2606 * Only clear out a write error when rewriting, should this
2607 * include WRITE_SYNC as well?
2608 */
2609 if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER))
2610 clear_buffer_write_io_error(bh);
2611
2612 /*
2613 * from here on down, it's all bio -- do the initial mapping,
2614 * submit_bio -> generic_make_request may further map this bio around
2615 */
2616 bio = bio_alloc(GFP_NOIO, 1);
2617
2618 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
2619 bio->bi_bdev = bh->b_bdev;
2620 bio->bi_io_vec[0].bv_page = bh->b_page;
2621 bio->bi_io_vec[0].bv_len = bh->b_size;
2622 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
2623
2624 bio->bi_vcnt = 1;
2625 bio->bi_idx = 0;
2626 bio->bi_size = bh->b_size;
2627
2628 bio->bi_end_io = end_bio_bh_io_sync;
2629 bio->bi_private = bh;
2630
2631 bio_get(bio);
2632 submit_bio(rw, bio);
2633
2634 if (bio_flagged(bio, BIO_EOPNOTSUPP))
2635 ret = -EOPNOTSUPP;
2636
2637 bio_put(bio);
2638 return ret;
2639}
2640
2641/**
2642 * ll_rw_block: low-level access to block devices (DEPRECATED)
Jan Karaa7662232005-09-06 15:19:10 -07002643 * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002644 * @nr: number of &struct buffer_heads in the array
2645 * @bhs: array of pointers to &struct buffer_head
2646 *
Jan Karaa7662232005-09-06 15:19:10 -07002647 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
2648 * requests an I/O operation on them, either a %READ or a %WRITE. The third
2649 * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
2650 * are sent to disk. The fourth %READA option is described in the documentation
2651 * for generic_make_request() which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002652 *
2653 * This function drops any buffer that it cannot get a lock on (with the
Jan Karaa7662232005-09-06 15:19:10 -07002654 * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
2655 * clean when doing a write request, and any buffer that appears to be
2656 * up-to-date when doing read request. Further it marks as clean buffers that
2657 * are processed for writing (the buffer cache won't assume that they are
2658 * actually clean until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002659 *
2660 * ll_rw_block sets b_end_io to simple completion handler that marks
2661 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
2662 * any waiters.
2663 *
2664 * All of the buffers must be for the same device, and must also be a
2665 * multiple of the current approved size for the device.
2666 */
2667void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
2668{
2669 int i;
2670
2671 for (i = 0; i < nr; i++) {
2672 struct buffer_head *bh = bhs[i];
2673
Jan Karaa7662232005-09-06 15:19:10 -07002674 if (rw == SWRITE)
2675 lock_buffer(bh);
2676 else if (test_set_buffer_locked(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677 continue;
2678
Jan Karaa7662232005-09-06 15:19:10 -07002679 if (rw == WRITE || rw == SWRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002680 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07002681 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08002682 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002683 submit_bh(WRITE, bh);
2684 continue;
2685 }
2686 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002687 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07002688 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08002689 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002690 submit_bh(rw, bh);
2691 continue;
2692 }
2693 }
2694 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002695 }
2696}
2697
2698/*
2699 * For a data-integrity writeout, we need to wait upon any in-progress I/O
2700 * and then start new I/O and then wait upon it. The caller must have a ref on
2701 * the buffer_head.
2702 */
2703int sync_dirty_buffer(struct buffer_head *bh)
2704{
2705 int ret = 0;
2706
2707 WARN_ON(atomic_read(&bh->b_count) < 1);
2708 lock_buffer(bh);
2709 if (test_clear_buffer_dirty(bh)) {
2710 get_bh(bh);
2711 bh->b_end_io = end_buffer_write_sync;
2712 ret = submit_bh(WRITE, bh);
2713 wait_on_buffer(bh);
2714 if (buffer_eopnotsupp(bh)) {
2715 clear_buffer_eopnotsupp(bh);
2716 ret = -EOPNOTSUPP;
2717 }
2718 if (!ret && !buffer_uptodate(bh))
2719 ret = -EIO;
2720 } else {
2721 unlock_buffer(bh);
2722 }
2723 return ret;
2724}
2725
2726/*
2727 * try_to_free_buffers() checks if all the buffers on this particular page
2728 * are unused, and releases them if so.
2729 *
2730 * Exclusion against try_to_free_buffers may be obtained by either
2731 * locking the page or by holding its mapping's private_lock.
2732 *
2733 * If the page is dirty but all the buffers are clean then we need to
2734 * be sure to mark the page clean as well. This is because the page
2735 * may be against a block device, and a later reattachment of buffers
2736 * to a dirty page will set *all* buffers dirty. Which would corrupt
2737 * filesystem data on the same device.
2738 *
2739 * The same applies to regular filesystem pages: if all the buffers are
2740 * clean then we set the page clean and proceed. To do that, we require
2741 * total exclusion from __set_page_dirty_buffers(). That is obtained with
2742 * private_lock.
2743 *
2744 * try_to_free_buffers() is non-blocking.
2745 */
2746static inline int buffer_busy(struct buffer_head *bh)
2747{
2748 return atomic_read(&bh->b_count) |
2749 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
2750}
2751
2752static int
2753drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
2754{
2755 struct buffer_head *head = page_buffers(page);
2756 struct buffer_head *bh;
2757
2758 bh = head;
2759 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07002760 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002761 set_bit(AS_EIO, &page->mapping->flags);
2762 if (buffer_busy(bh))
2763 goto failed;
2764 bh = bh->b_this_page;
2765 } while (bh != head);
2766
2767 do {
2768 struct buffer_head *next = bh->b_this_page;
2769
2770 if (!list_empty(&bh->b_assoc_buffers))
2771 __remove_assoc_queue(bh);
2772 bh = next;
2773 } while (bh != head);
2774 *buffers_to_free = head;
2775 __clear_page_buffers(page);
2776 return 1;
2777failed:
2778 return 0;
2779}
2780
2781int try_to_free_buffers(struct page *page)
2782{
2783 struct address_space * const mapping = page->mapping;
2784 struct buffer_head *buffers_to_free = NULL;
2785 int ret = 0;
2786
2787 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08002788 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002789 return 0;
2790
2791 if (mapping == NULL) { /* can this still happen? */
2792 ret = drop_buffers(page, &buffers_to_free);
2793 goto out;
2794 }
2795
2796 spin_lock(&mapping->private_lock);
2797 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08002798
2799 /*
2800 * If the filesystem writes its buffers by hand (eg ext3)
2801 * then we can have clean buffers against a dirty page. We
2802 * clean the page here; otherwise the VM will never notice
2803 * that the filesystem did any IO at all.
2804 *
2805 * Also, during truncate, discard_buffer will have marked all
2806 * the page's buffers clean. We discover that here and clean
2807 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11002808 *
2809 * private_lock must be held over this entire operation in order
2810 * to synchronise against __set_page_dirty_buffers and prevent the
2811 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08002812 */
2813 if (ret)
2814 cancel_dirty_page(page, PAGE_CACHE_SIZE);
Nick Piggin87df7242007-01-30 14:36:27 +11002815 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002816out:
2817 if (buffers_to_free) {
2818 struct buffer_head *bh = buffers_to_free;
2819
2820 do {
2821 struct buffer_head *next = bh->b_this_page;
2822 free_buffer_head(bh);
2823 bh = next;
2824 } while (bh != buffers_to_free);
2825 }
2826 return ret;
2827}
2828EXPORT_SYMBOL(try_to_free_buffers);
2829
NeilBrown3978d7172006-03-26 01:37:17 -08002830void block_sync_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002831{
2832 struct address_space *mapping;
2833
2834 smp_mb();
2835 mapping = page_mapping(page);
2836 if (mapping)
2837 blk_run_backing_dev(mapping->backing_dev_info, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002838}
2839
2840/*
2841 * There are no bdflush tunables left. But distributions are
2842 * still running obsolete flush daemons, so we terminate them here.
2843 *
2844 * Use of bdflush() is deprecated and will be removed in a future kernel.
2845 * The `pdflush' kernel threads fully replace bdflush daemons and this call.
2846 */
2847asmlinkage long sys_bdflush(int func, long data)
2848{
2849 static int msg_count;
2850
2851 if (!capable(CAP_SYS_ADMIN))
2852 return -EPERM;
2853
2854 if (msg_count < 5) {
2855 msg_count++;
2856 printk(KERN_INFO
2857 "warning: process `%s' used the obsolete bdflush"
2858 " system call\n", current->comm);
2859 printk(KERN_INFO "Fix your initscripts?\n");
2860 }
2861
2862 if (func == 1)
2863 do_exit(0);
2864 return 0;
2865}
2866
2867/*
2868 * Buffer-head allocation
2869 */
Christoph Lametere18b8902006-12-06 20:33:20 -08002870static struct kmem_cache *bh_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871
2872/*
2873 * Once the number of bh's in the machine exceeds this level, we start
2874 * stripping them in writeback.
2875 */
2876static int max_buffer_heads;
2877
2878int buffer_heads_over_limit;
2879
2880struct bh_accounting {
2881 int nr; /* Number of live bh's */
2882 int ratelimit; /* Limit cacheline bouncing */
2883};
2884
2885static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
2886
2887static void recalc_bh_state(void)
2888{
2889 int i;
2890 int tot = 0;
2891
2892 if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
2893 return;
2894 __get_cpu_var(bh_accounting).ratelimit = 0;
Eric Dumazet8a143422006-03-24 03:18:10 -08002895 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002896 tot += per_cpu(bh_accounting, i).nr;
2897 buffer_heads_over_limit = (tot > max_buffer_heads);
2898}
2899
Al Virodd0fc662005-10-07 07:46:04 +01002900struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002901{
Christoph Lametera35afb82007-05-16 22:10:57 -07002902 struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002903 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07002904 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07002905 get_cpu_var(bh_accounting).nr++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002906 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07002907 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002908 }
2909 return ret;
2910}
2911EXPORT_SYMBOL(alloc_buffer_head);
2912
2913void free_buffer_head(struct buffer_head *bh)
2914{
2915 BUG_ON(!list_empty(&bh->b_assoc_buffers));
2916 kmem_cache_free(bh_cachep, bh);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07002917 get_cpu_var(bh_accounting).nr--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002918 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07002919 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002920}
2921EXPORT_SYMBOL(free_buffer_head);
2922
Linus Torvalds1da177e2005-04-16 15:20:36 -07002923static void buffer_exit_cpu(int cpu)
2924{
2925 int i;
2926 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
2927
2928 for (i = 0; i < BH_LRU_SIZE; i++) {
2929 brelse(b->bhs[i]);
2930 b->bhs[i] = NULL;
2931 }
Eric Dumazet8a143422006-03-24 03:18:10 -08002932 get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr;
2933 per_cpu(bh_accounting, cpu).nr = 0;
2934 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002935}
2936
2937static int buffer_cpu_notify(struct notifier_block *self,
2938 unsigned long action, void *hcpu)
2939{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07002940 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002941 buffer_exit_cpu((unsigned long)hcpu);
2942 return NOTIFY_OK;
2943}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002944
2945void __init buffer_init(void)
2946{
2947 int nrpages;
2948
Christoph Lametera35afb82007-05-16 22:10:57 -07002949 bh_cachep = KMEM_CACHE(buffer_head,
2950 SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002951
2952 /*
2953 * Limit the bh occupancy to 10% of ZONE_NORMAL
2954 */
2955 nrpages = (nr_free_buffer_pages() * 10) / 100;
2956 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
2957 hotcpu_notifier(buffer_cpu_notify, 0);
2958}
2959
2960EXPORT_SYMBOL(__bforget);
2961EXPORT_SYMBOL(__brelse);
2962EXPORT_SYMBOL(__wait_on_buffer);
2963EXPORT_SYMBOL(block_commit_write);
2964EXPORT_SYMBOL(block_prepare_write);
2965EXPORT_SYMBOL(block_read_full_page);
2966EXPORT_SYMBOL(block_sync_page);
2967EXPORT_SYMBOL(block_truncate_page);
2968EXPORT_SYMBOL(block_write_full_page);
2969EXPORT_SYMBOL(cont_prepare_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002970EXPORT_SYMBOL(end_buffer_read_sync);
2971EXPORT_SYMBOL(end_buffer_write_sync);
2972EXPORT_SYMBOL(file_fsync);
2973EXPORT_SYMBOL(fsync_bdev);
2974EXPORT_SYMBOL(generic_block_bmap);
2975EXPORT_SYMBOL(generic_commit_write);
2976EXPORT_SYMBOL(generic_cont_expand);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002977EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978EXPORT_SYMBOL(init_buffer);
2979EXPORT_SYMBOL(invalidate_bdev);
2980EXPORT_SYMBOL(ll_rw_block);
2981EXPORT_SYMBOL(mark_buffer_dirty);
2982EXPORT_SYMBOL(submit_bh);
2983EXPORT_SYMBOL(sync_dirty_buffer);
2984EXPORT_SYMBOL(unlock_buffer);