blob: 373bb6292bdc137a606296c7864093470d41b00f [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
21#include <linux/config.h>
22#include <linux/kernel.h>
23#include <linux/syscalls.h>
24#include <linux/fs.h>
25#include <linux/mm.h>
26#include <linux/percpu.h>
27#include <linux/slab.h>
28#include <linux/smp_lock.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080029#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include <linux/blkdev.h>
31#include <linux/file.h>
32#include <linux/quotaops.h>
33#include <linux/highmem.h>
34#include <linux/module.h>
35#include <linux/writeback.h>
36#include <linux/hash.h>
37#include <linux/suspend.h>
38#include <linux/buffer_head.h>
39#include <linux/bio.h>
40#include <linux/notifier.h>
41#include <linux/cpu.h>
42#include <linux/bitops.h>
43#include <linux/mpage.h>
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070044#include <linux/bit_spinlock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045
46static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
47static void invalidate_bh_lrus(void);
48
49#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
50
51inline void
52init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
53{
54 bh->b_end_io = handler;
55 bh->b_private = private;
56}
57
58static int sync_buffer(void *word)
59{
60 struct block_device *bd;
61 struct buffer_head *bh
62 = container_of(word, struct buffer_head, b_state);
63
64 smp_mb();
65 bd = bh->b_bdev;
66 if (bd)
67 blk_run_address_space(bd->bd_inode->i_mapping);
68 io_schedule();
69 return 0;
70}
71
72void fastcall __lock_buffer(struct buffer_head *bh)
73{
74 wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer,
75 TASK_UNINTERRUPTIBLE);
76}
77EXPORT_SYMBOL(__lock_buffer);
78
79void fastcall unlock_buffer(struct buffer_head *bh)
80{
81 clear_buffer_locked(bh);
82 smp_mb__after_clear_bit();
83 wake_up_bit(&bh->b_state, BH_Lock);
84}
85
86/*
87 * Block until a buffer comes unlocked. This doesn't stop it
88 * from becoming locked again - you have to lock it yourself
89 * if you want to preserve its state.
90 */
91void __wait_on_buffer(struct buffer_head * bh)
92{
93 wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE);
94}
95
96static void
97__clear_page_buffers(struct page *page)
98{
99 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700100 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 page_cache_release(page);
102}
103
104static void buffer_io_error(struct buffer_head *bh)
105{
106 char b[BDEVNAME_SIZE];
107
108 printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
109 bdevname(bh->b_bdev, b),
110 (unsigned long long)bh->b_blocknr);
111}
112
113/*
114 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
115 * unlock the buffer. This is what ll_rw_block uses too.
116 */
117void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
118{
119 if (uptodate) {
120 set_buffer_uptodate(bh);
121 } else {
122 /* This happens, due to failed READA attempts. */
123 clear_buffer_uptodate(bh);
124 }
125 unlock_buffer(bh);
126 put_bh(bh);
127}
128
129void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
130{
131 char b[BDEVNAME_SIZE];
132
133 if (uptodate) {
134 set_buffer_uptodate(bh);
135 } else {
136 if (!buffer_eopnotsupp(bh) && printk_ratelimit()) {
137 buffer_io_error(bh);
138 printk(KERN_WARNING "lost page write due to "
139 "I/O error on %s\n",
140 bdevname(bh->b_bdev, b));
141 }
142 set_buffer_write_io_error(bh);
143 clear_buffer_uptodate(bh);
144 }
145 unlock_buffer(bh);
146 put_bh(bh);
147}
148
149/*
150 * Write out and wait upon all the dirty data associated with a block
151 * device via its mapping. Does not take the superblock lock.
152 */
153int sync_blockdev(struct block_device *bdev)
154{
155 int ret = 0;
156
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800157 if (bdev)
158 ret = filemap_write_and_wait(bdev->bd_inode->i_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 return ret;
160}
161EXPORT_SYMBOL(sync_blockdev);
162
OGAWA Hirofumid25b9a12006-03-25 03:07:44 -0800163static void __fsync_super(struct super_block *sb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164{
165 sync_inodes_sb(sb, 0);
166 DQUOT_SYNC(sb);
167 lock_super(sb);
168 if (sb->s_dirt && sb->s_op->write_super)
169 sb->s_op->write_super(sb);
170 unlock_super(sb);
171 if (sb->s_op->sync_fs)
172 sb->s_op->sync_fs(sb, 1);
173 sync_blockdev(sb->s_bdev);
174 sync_inodes_sb(sb, 1);
OGAWA Hirofumid25b9a12006-03-25 03:07:44 -0800175}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176
OGAWA Hirofumid25b9a12006-03-25 03:07:44 -0800177/*
178 * Write out and wait upon all dirty data associated with this
179 * superblock. Filesystem data as well as the underlying block
180 * device. Takes the superblock lock.
181 */
182int fsync_super(struct super_block *sb)
183{
184 __fsync_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 return sync_blockdev(sb->s_bdev);
186}
187
188/*
189 * Write out and wait upon all dirty data associated with this
190 * device. Filesystem data as well as the underlying block
191 * device. Takes the superblock lock.
192 */
193int fsync_bdev(struct block_device *bdev)
194{
195 struct super_block *sb = get_super(bdev);
196 if (sb) {
197 int res = fsync_super(sb);
198 drop_super(sb);
199 return res;
200 }
201 return sync_blockdev(bdev);
202}
203
204/**
205 * freeze_bdev -- lock a filesystem and force it into a consistent state
206 * @bdev: blockdevice to lock
207 *
Arjan van de Venc039e312006-03-23 03:00:28 -0800208 * This takes the block device bd_mount_mutex to make sure no new mounts
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 * happen on bdev until thaw_bdev() is called.
210 * If a superblock is found on this device, we take the s_umount semaphore
211 * on it to make sure nobody unmounts until the snapshot creation is done.
212 */
213struct super_block *freeze_bdev(struct block_device *bdev)
214{
215 struct super_block *sb;
216
Arjan van de Venc039e312006-03-23 03:00:28 -0800217 mutex_lock(&bdev->bd_mount_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 sb = get_super(bdev);
219 if (sb && !(sb->s_flags & MS_RDONLY)) {
220 sb->s_frozen = SB_FREEZE_WRITE;
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700221 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222
OGAWA Hirofumid25b9a12006-03-25 03:07:44 -0800223 __fsync_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224
225 sb->s_frozen = SB_FREEZE_TRANS;
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700226 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
228 sync_blockdev(sb->s_bdev);
229
230 if (sb->s_op->write_super_lockfs)
231 sb->s_op->write_super_lockfs(sb);
232 }
233
234 sync_blockdev(bdev);
235 return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */
236}
237EXPORT_SYMBOL(freeze_bdev);
238
239/**
240 * thaw_bdev -- unlock filesystem
241 * @bdev: blockdevice to unlock
242 * @sb: associated superblock
243 *
244 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
245 */
246void thaw_bdev(struct block_device *bdev, struct super_block *sb)
247{
248 if (sb) {
249 BUG_ON(sb->s_bdev != bdev);
250
251 if (sb->s_op->unlockfs)
252 sb->s_op->unlockfs(sb);
253 sb->s_frozen = SB_UNFROZEN;
akpm@osdl.orgd59dd462005-05-01 08:58:47 -0700254 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 wake_up(&sb->s_wait_unfrozen);
256 drop_super(sb);
257 }
258
Arjan van de Venc039e312006-03-23 03:00:28 -0800259 mutex_unlock(&bdev->bd_mount_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260}
261EXPORT_SYMBOL(thaw_bdev);
262
263/*
264 * sync everything. Start out by waking pdflush, because that writes back
265 * all queues in parallel.
266 */
267static void do_sync(unsigned long wait)
268{
Pekka J Enberg687a21c2005-06-28 20:44:55 -0700269 wakeup_pdflush(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 sync_inodes(0); /* All mappings, inodes and their blockdevs */
271 DQUOT_SYNC(NULL);
272 sync_supers(); /* Write the superblocks */
273 sync_filesystems(0); /* Start syncing the filesystems */
274 sync_filesystems(wait); /* Waitingly sync the filesystems */
275 sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */
276 if (!wait)
277 printk("Emergency Sync complete\n");
278 if (unlikely(laptop_mode))
279 laptop_sync_completion();
280}
281
282asmlinkage long sys_sync(void)
283{
284 do_sync(1);
285 return 0;
286}
287
288void emergency_sync(void)
289{
290 pdflush_operation(do_sync, 0);
291}
292
293/*
294 * Generic function to fsync a file.
295 *
296 * filp may be NULL if called via the msync of a vma.
297 */
298
299int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
300{
301 struct inode * inode = dentry->d_inode;
302 struct super_block * sb;
303 int ret, err;
304
305 /* sync the inode to buffers */
306 ret = write_inode_now(inode, 0);
307
308 /* sync the superblock to buffers */
309 sb = inode->i_sb;
310 lock_super(sb);
311 if (sb->s_op->write_super)
312 sb->s_op->write_super(sb);
313 unlock_super(sb);
314
315 /* .. finally sync the buffers to disk */
316 err = sync_blockdev(sb->s_bdev);
317 if (!ret)
318 ret = err;
319 return ret;
320}
321
Andrew Morton18e79b42006-03-24 03:18:14 -0800322long do_fsync(struct file *file, int datasync)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323{
Andrew Morton18e79b42006-03-24 03:18:14 -0800324 int ret;
325 int err;
326 struct address_space *mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 if (!file->f_op || !file->f_op->fsync) {
329 /* Why? We can still call filemap_fdatawrite */
Andrew Morton18e79b42006-03-24 03:18:14 -0800330 ret = -EINVAL;
331 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332 }
333
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 ret = filemap_fdatawrite(mapping);
335
336 /*
Andrew Morton18e79b42006-03-24 03:18:14 -0800337 * We need to protect against concurrent writers, which could cause
338 * livelocks in fsync_buffers_list().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339 */
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800340 mutex_lock(&mapping->host->i_mutex);
Oleg Nesterovdfb388b2005-06-23 00:10:02 -0700341 err = file->f_op->fsync(file, file->f_dentry, datasync);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 if (!ret)
343 ret = err;
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800344 mutex_unlock(&mapping->host->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 err = filemap_fdatawait(mapping);
346 if (!ret)
347 ret = err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348out:
349 return ret;
350}
351
Andrew Morton18e79b42006-03-24 03:18:14 -0800352static long __do_fsync(unsigned int fd, int datasync)
353{
354 struct file *file;
355 int ret = -EBADF;
356
357 file = fget(fd);
358 if (file) {
359 ret = do_fsync(file, datasync);
360 fput(file);
361 }
362 return ret;
363}
364
Oleg Nesterovdfb388b2005-06-23 00:10:02 -0700365asmlinkage long sys_fsync(unsigned int fd)
366{
Andrew Morton18e79b42006-03-24 03:18:14 -0800367 return __do_fsync(fd, 0);
Oleg Nesterovdfb388b2005-06-23 00:10:02 -0700368}
369
Linus Torvalds1da177e2005-04-16 15:20:36 -0700370asmlinkage long sys_fdatasync(unsigned int fd)
371{
Andrew Morton18e79b42006-03-24 03:18:14 -0800372 return __do_fsync(fd, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373}
374
375/*
376 * Various filesystems appear to want __find_get_block to be non-blocking.
377 * But it's the page lock which protects the buffers. To get around this,
378 * we get exclusion from try_to_free_buffers with the blockdev mapping's
379 * private_lock.
380 *
381 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
382 * may be quite high. This code could TryLock the page, and if that
383 * succeeds, there is no need to take private_lock. (But if
384 * private_lock is contended then so is mapping->tree_lock).
385 */
386static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800387__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388{
389 struct inode *bd_inode = bdev->bd_inode;
390 struct address_space *bd_mapping = bd_inode->i_mapping;
391 struct buffer_head *ret = NULL;
392 pgoff_t index;
393 struct buffer_head *bh;
394 struct buffer_head *head;
395 struct page *page;
396 int all_mapped = 1;
397
398 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
399 page = find_get_page(bd_mapping, index);
400 if (!page)
401 goto out;
402
403 spin_lock(&bd_mapping->private_lock);
404 if (!page_has_buffers(page))
405 goto out_unlock;
406 head = page_buffers(page);
407 bh = head;
408 do {
409 if (bh->b_blocknr == block) {
410 ret = bh;
411 get_bh(bh);
412 goto out_unlock;
413 }
414 if (!buffer_mapped(bh))
415 all_mapped = 0;
416 bh = bh->b_this_page;
417 } while (bh != head);
418
419 /* we might be here because some of the buffers on this page are
420 * not mapped. This is due to various races between
421 * file io on the block device and getblk. It gets dealt with
422 * elsewhere, don't buffer_error if we had some unmapped buffers
423 */
424 if (all_mapped) {
425 printk("__find_get_block_slow() failed. "
426 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800427 (unsigned long long)block,
428 (unsigned long long)bh->b_blocknr);
429 printk("b_state=0x%08lx, b_size=%zu\n",
430 bh->b_state, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
432 }
433out_unlock:
434 spin_unlock(&bd_mapping->private_lock);
435 page_cache_release(page);
436out:
437 return ret;
438}
439
440/* If invalidate_buffers() will trash dirty buffers, it means some kind
441 of fs corruption is going on. Trashing dirty data always imply losing
442 information that was supposed to be just stored on the physical layer
443 by the user.
444
445 Thus invalidate_buffers in general usage is not allwowed to trash
446 dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
447 be preserved. These buffers are simply skipped.
448
449 We also skip buffers which are still in use. For example this can
450 happen if a userspace program is reading the block device.
451
452 NOTE: In the case where the user removed a removable-media-disk even if
453 there's still dirty data not synced on disk (due a bug in the device driver
454 or due an error of the user), by not destroying the dirty buffers we could
455 generate corruption also on the next media inserted, thus a parameter is
456 necessary to handle this case in the most safe way possible (trying
457 to not corrupt also the new disk inserted with the data belonging to
458 the old now corrupted disk). Also for the ramdisk the natural thing
459 to do in order to release the ramdisk memory is to destroy dirty buffers.
460
461 These are two special cases. Normal usage imply the device driver
462 to issue a sync on the device (without waiting I/O completion) and
463 then an invalidate_buffers call that doesn't trash dirty buffers.
464
465 For handling cache coherency with the blkdev pagecache the 'update' case
466 is been introduced. It is needed to re-read from disk any pinned
467 buffer. NOTE: re-reading from disk is destructive so we can do it only
468 when we assume nobody is changing the buffercache under our I/O and when
469 we think the disk contains more recent information than the buffercache.
470 The update == 1 pass marks the buffers we need to update, the update == 2
471 pass does the actual I/O. */
472void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers)
473{
474 invalidate_bh_lrus();
475 /*
476 * FIXME: what about destroy_dirty_buffers?
477 * We really want to use invalidate_inode_pages2() for
478 * that, but not until that's cleaned up.
479 */
480 invalidate_inode_pages(bdev->bd_inode->i_mapping);
481}
482
483/*
484 * Kick pdflush then try to free up some ZONE_NORMAL memory.
485 */
486static void free_more_memory(void)
487{
488 struct zone **zones;
489 pg_data_t *pgdat;
490
Pekka J Enberg687a21c2005-06-28 20:44:55 -0700491 wakeup_pdflush(1024);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 yield();
493
KAMEZAWA Hiroyukiec936fc2006-03-27 01:15:59 -0800494 for_each_online_pgdat(pgdat) {
Al Viroaf4ca452005-10-21 02:55:38 -0400495 zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496 if (*zones)
Darren Hart1ad539b2005-06-21 17:14:53 -0700497 try_to_free_pages(zones, GFP_NOFS);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700498 }
499}
500
501/*
502 * I/O completion handler for block_read_full_page() - pages
503 * which come unlocked at the end of I/O.
504 */
505static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
506{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700508 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 struct buffer_head *tmp;
510 struct page *page;
511 int page_uptodate = 1;
512
513 BUG_ON(!buffer_async_read(bh));
514
515 page = bh->b_page;
516 if (uptodate) {
517 set_buffer_uptodate(bh);
518 } else {
519 clear_buffer_uptodate(bh);
520 if (printk_ratelimit())
521 buffer_io_error(bh);
522 SetPageError(page);
523 }
524
525 /*
526 * Be _very_ careful from here on. Bad things can happen if
527 * two buffer heads end IO at almost the same time and both
528 * decide that the page is now completely done.
529 */
Nick Piggina3972202005-07-07 17:56:56 -0700530 first = page_buffers(page);
531 local_irq_save(flags);
532 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 clear_buffer_async_read(bh);
534 unlock_buffer(bh);
535 tmp = bh;
536 do {
537 if (!buffer_uptodate(tmp))
538 page_uptodate = 0;
539 if (buffer_async_read(tmp)) {
540 BUG_ON(!buffer_locked(tmp));
541 goto still_busy;
542 }
543 tmp = tmp->b_this_page;
544 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700545 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
546 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547
548 /*
549 * If none of the buffers had errors and they are all
550 * uptodate then we can set the page uptodate.
551 */
552 if (page_uptodate && !PageError(page))
553 SetPageUptodate(page);
554 unlock_page(page);
555 return;
556
557still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700558 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
559 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 return;
561}
562
563/*
564 * Completion handler for block_write_full_page() - pages which are unlocked
565 * during I/O, and which have PageWriteback cleared upon I/O completion.
566 */
567void end_buffer_async_write(struct buffer_head *bh, int uptodate)
568{
569 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700571 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 struct buffer_head *tmp;
573 struct page *page;
574
575 BUG_ON(!buffer_async_write(bh));
576
577 page = bh->b_page;
578 if (uptodate) {
579 set_buffer_uptodate(bh);
580 } else {
581 if (printk_ratelimit()) {
582 buffer_io_error(bh);
583 printk(KERN_WARNING "lost page write due to "
584 "I/O error on %s\n",
585 bdevname(bh->b_bdev, b));
586 }
587 set_bit(AS_EIO, &page->mapping->flags);
588 clear_buffer_uptodate(bh);
589 SetPageError(page);
590 }
591
Nick Piggina3972202005-07-07 17:56:56 -0700592 first = page_buffers(page);
593 local_irq_save(flags);
594 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
595
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 clear_buffer_async_write(bh);
597 unlock_buffer(bh);
598 tmp = bh->b_this_page;
599 while (tmp != bh) {
600 if (buffer_async_write(tmp)) {
601 BUG_ON(!buffer_locked(tmp));
602 goto still_busy;
603 }
604 tmp = tmp->b_this_page;
605 }
Nick Piggina3972202005-07-07 17:56:56 -0700606 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
607 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700608 end_page_writeback(page);
609 return;
610
611still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700612 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
613 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700614 return;
615}
616
617/*
618 * If a page's buffers are under async readin (end_buffer_async_read
619 * completion) then there is a possibility that another thread of
620 * control could lock one of the buffers after it has completed
621 * but while some of the other buffers have not completed. This
622 * locked buffer would confuse end_buffer_async_read() into not unlocking
623 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
624 * that this buffer is not under async I/O.
625 *
626 * The page comes unlocked when it has no locked buffer_async buffers
627 * left.
628 *
629 * PageLocked prevents anyone starting new async I/O reads any of
630 * the buffers.
631 *
632 * PageWriteback is used to prevent simultaneous writeout of the same
633 * page.
634 *
635 * PageLocked prevents anyone from starting writeback of a page which is
636 * under read I/O (PageWriteback is only ever set against a locked page).
637 */
638static void mark_buffer_async_read(struct buffer_head *bh)
639{
640 bh->b_end_io = end_buffer_async_read;
641 set_buffer_async_read(bh);
642}
643
644void mark_buffer_async_write(struct buffer_head *bh)
645{
646 bh->b_end_io = end_buffer_async_write;
647 set_buffer_async_write(bh);
648}
649EXPORT_SYMBOL(mark_buffer_async_write);
650
651
652/*
653 * fs/buffer.c contains helper functions for buffer-backed address space's
654 * fsync functions. A common requirement for buffer-based filesystems is
655 * that certain data from the backing blockdev needs to be written out for
656 * a successful fsync(). For example, ext2 indirect blocks need to be
657 * written back and waited upon before fsync() returns.
658 *
659 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
660 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
661 * management of a list of dependent buffers at ->i_mapping->private_list.
662 *
663 * Locking is a little subtle: try_to_free_buffers() will remove buffers
664 * from their controlling inode's queue when they are being freed. But
665 * try_to_free_buffers() will be operating against the *blockdev* mapping
666 * at the time, not against the S_ISREG file which depends on those buffers.
667 * So the locking for private_list is via the private_lock in the address_space
668 * which backs the buffers. Which is different from the address_space
669 * against which the buffers are listed. So for a particular address_space,
670 * mapping->private_lock does *not* protect mapping->private_list! In fact,
671 * mapping->private_list will always be protected by the backing blockdev's
672 * ->private_lock.
673 *
674 * Which introduces a requirement: all buffers on an address_space's
675 * ->private_list must be from the same address_space: the blockdev's.
676 *
677 * address_spaces which do not place buffers at ->private_list via these
678 * utility functions are free to use private_lock and private_list for
679 * whatever they want. The only requirement is that list_empty(private_list)
680 * be true at clear_inode() time.
681 *
682 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
683 * filesystems should do that. invalidate_inode_buffers() should just go
684 * BUG_ON(!list_empty).
685 *
686 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
687 * take an address_space, not an inode. And it should be called
688 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
689 * queued up.
690 *
691 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
692 * list if it is already on a list. Because if the buffer is on a list,
693 * it *must* already be on the right one. If not, the filesystem is being
694 * silly. This will save a ton of locking. But first we have to ensure
695 * that buffers are taken *off* the old inode's list when they are freed
696 * (presumably in truncate). That requires careful auditing of all
697 * filesystems (do it inside bforget()). It could also be done by bringing
698 * b_inode back.
699 */
700
701/*
702 * The buffer's backing address_space's private_lock must be held
703 */
704static inline void __remove_assoc_queue(struct buffer_head *bh)
705{
706 list_del_init(&bh->b_assoc_buffers);
707}
708
709int inode_has_buffers(struct inode *inode)
710{
711 return !list_empty(&inode->i_data.private_list);
712}
713
714/*
715 * osync is designed to support O_SYNC io. It waits synchronously for
716 * all already-submitted IO to complete, but does not queue any new
717 * writes to the disk.
718 *
719 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
720 * you dirty the buffers, and then use osync_inode_buffers to wait for
721 * completion. Any other dirty buffers which are not yet queued for
722 * write will not be flushed to disk by the osync.
723 */
724static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
725{
726 struct buffer_head *bh;
727 struct list_head *p;
728 int err = 0;
729
730 spin_lock(lock);
731repeat:
732 list_for_each_prev(p, list) {
733 bh = BH_ENTRY(p);
734 if (buffer_locked(bh)) {
735 get_bh(bh);
736 spin_unlock(lock);
737 wait_on_buffer(bh);
738 if (!buffer_uptodate(bh))
739 err = -EIO;
740 brelse(bh);
741 spin_lock(lock);
742 goto repeat;
743 }
744 }
745 spin_unlock(lock);
746 return err;
747}
748
749/**
750 * sync_mapping_buffers - write out and wait upon a mapping's "associated"
751 * buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700752 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 *
754 * Starts I/O against the buffers at mapping->private_list, and waits upon
755 * that I/O.
756 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700757 * Basically, this is a convenience function for fsync().
758 * @mapping is a file or directory which needs those buffers to be written for
759 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 */
761int sync_mapping_buffers(struct address_space *mapping)
762{
763 struct address_space *buffer_mapping = mapping->assoc_mapping;
764
765 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
766 return 0;
767
768 return fsync_buffers_list(&buffer_mapping->private_lock,
769 &mapping->private_list);
770}
771EXPORT_SYMBOL(sync_mapping_buffers);
772
773/*
774 * Called when we've recently written block `bblock', and it is known that
775 * `bblock' was for a buffer_boundary() buffer. This means that the block at
776 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
777 * dirty, schedule it for IO. So that indirects merge nicely with their data.
778 */
779void write_boundary_block(struct block_device *bdev,
780 sector_t bblock, unsigned blocksize)
781{
782 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
783 if (bh) {
784 if (buffer_dirty(bh))
785 ll_rw_block(WRITE, 1, &bh);
786 put_bh(bh);
787 }
788}
789
790void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
791{
792 struct address_space *mapping = inode->i_mapping;
793 struct address_space *buffer_mapping = bh->b_page->mapping;
794
795 mark_buffer_dirty(bh);
796 if (!mapping->assoc_mapping) {
797 mapping->assoc_mapping = buffer_mapping;
798 } else {
Eric Sesterhenne827f922006-03-26 18:24:46 +0200799 BUG_ON(mapping->assoc_mapping != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 }
801 if (list_empty(&bh->b_assoc_buffers)) {
802 spin_lock(&buffer_mapping->private_lock);
803 list_move_tail(&bh->b_assoc_buffers,
804 &mapping->private_list);
805 spin_unlock(&buffer_mapping->private_lock);
806 }
807}
808EXPORT_SYMBOL(mark_buffer_dirty_inode);
809
810/*
811 * Add a page to the dirty page list.
812 *
813 * It is a sad fact of life that this function is called from several places
814 * deeply under spinlocking. It may not sleep.
815 *
816 * If the page has buffers, the uptodate buffers are set dirty, to preserve
817 * dirty-state coherency between the page and the buffers. It the page does
818 * not have buffers then when they are later attached they will all be set
819 * dirty.
820 *
821 * The buffers are dirtied before the page is dirtied. There's a small race
822 * window in which a writepage caller may see the page cleanness but not the
823 * buffer dirtiness. That's fine. If this code were to set the page dirty
824 * before the buffers, a concurrent writepage caller could clear the page dirty
825 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
826 * page on the dirty page list.
827 *
828 * We use private_lock to lock against try_to_free_buffers while using the
829 * page's buffer list. Also use this to protect against clean buffers being
830 * added to the page after it was set dirty.
831 *
832 * FIXME: may need to call ->reservepage here as well. That's rather up to the
833 * address_space though.
834 */
835int __set_page_dirty_buffers(struct page *page)
836{
837 struct address_space * const mapping = page->mapping;
838
839 spin_lock(&mapping->private_lock);
840 if (page_has_buffers(page)) {
841 struct buffer_head *head = page_buffers(page);
842 struct buffer_head *bh = head;
843
844 do {
845 set_buffer_dirty(bh);
846 bh = bh->b_this_page;
847 } while (bh != head);
848 }
849 spin_unlock(&mapping->private_lock);
850
851 if (!TestSetPageDirty(page)) {
852 write_lock_irq(&mapping->tree_lock);
853 if (page->mapping) { /* Race with truncate? */
854 if (mapping_cap_account_dirty(mapping))
855 inc_page_state(nr_dirty);
856 radix_tree_tag_set(&mapping->page_tree,
857 page_index(page),
858 PAGECACHE_TAG_DIRTY);
859 }
860 write_unlock_irq(&mapping->tree_lock);
861 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Andrew Morton4741c9f2006-03-24 03:18:11 -0800862 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 return 0;
865}
866EXPORT_SYMBOL(__set_page_dirty_buffers);
867
868/*
869 * Write out and wait upon a list of buffers.
870 *
871 * We have conflicting pressures: we want to make sure that all
872 * initially dirty buffers get waited on, but that any subsequently
873 * dirtied buffers don't. After all, we don't want fsync to last
874 * forever if somebody is actively writing to the file.
875 *
876 * Do this in two main stages: first we copy dirty buffers to a
877 * temporary inode list, queueing the writes as we go. Then we clean
878 * up, waiting for those writes to complete.
879 *
880 * During this second stage, any subsequent updates to the file may end
881 * up refiling the buffer on the original inode's dirty list again, so
882 * there is a chance we will end up with a buffer queued for write but
883 * not yet completed on that list. So, as a final cleanup we go through
884 * the osync code to catch these locked, dirty buffers without requeuing
885 * any newly dirty buffers for write.
886 */
887static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
888{
889 struct buffer_head *bh;
890 struct list_head tmp;
891 int err = 0, err2;
892
893 INIT_LIST_HEAD(&tmp);
894
895 spin_lock(lock);
896 while (!list_empty(list)) {
897 bh = BH_ENTRY(list->next);
898 list_del_init(&bh->b_assoc_buffers);
899 if (buffer_dirty(bh) || buffer_locked(bh)) {
900 list_add(&bh->b_assoc_buffers, &tmp);
901 if (buffer_dirty(bh)) {
902 get_bh(bh);
903 spin_unlock(lock);
904 /*
905 * Ensure any pending I/O completes so that
906 * ll_rw_block() actually writes the current
907 * contents - it is a noop if I/O is still in
908 * flight on potentially older contents.
909 */
Jan Karaa7662232005-09-06 15:19:10 -0700910 ll_rw_block(SWRITE, 1, &bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 brelse(bh);
912 spin_lock(lock);
913 }
914 }
915 }
916
917 while (!list_empty(&tmp)) {
918 bh = BH_ENTRY(tmp.prev);
919 __remove_assoc_queue(bh);
920 get_bh(bh);
921 spin_unlock(lock);
922 wait_on_buffer(bh);
923 if (!buffer_uptodate(bh))
924 err = -EIO;
925 brelse(bh);
926 spin_lock(lock);
927 }
928
929 spin_unlock(lock);
930 err2 = osync_buffers_list(lock, list);
931 if (err)
932 return err;
933 else
934 return err2;
935}
936
937/*
938 * Invalidate any and all dirty buffers on a given inode. We are
939 * probably unmounting the fs, but that doesn't mean we have already
940 * done a sync(). Just drop the buffers from the inode list.
941 *
942 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
943 * assumes that all the buffers are against the blockdev. Not true
944 * for reiserfs.
945 */
946void invalidate_inode_buffers(struct inode *inode)
947{
948 if (inode_has_buffers(inode)) {
949 struct address_space *mapping = &inode->i_data;
950 struct list_head *list = &mapping->private_list;
951 struct address_space *buffer_mapping = mapping->assoc_mapping;
952
953 spin_lock(&buffer_mapping->private_lock);
954 while (!list_empty(list))
955 __remove_assoc_queue(BH_ENTRY(list->next));
956 spin_unlock(&buffer_mapping->private_lock);
957 }
958}
959
960/*
961 * Remove any clean buffers from the inode's buffer list. This is called
962 * when we're trying to free the inode itself. Those buffers can pin it.
963 *
964 * Returns true if all buffers were removed.
965 */
966int remove_inode_buffers(struct inode *inode)
967{
968 int ret = 1;
969
970 if (inode_has_buffers(inode)) {
971 struct address_space *mapping = &inode->i_data;
972 struct list_head *list = &mapping->private_list;
973 struct address_space *buffer_mapping = mapping->assoc_mapping;
974
975 spin_lock(&buffer_mapping->private_lock);
976 while (!list_empty(list)) {
977 struct buffer_head *bh = BH_ENTRY(list->next);
978 if (buffer_dirty(bh)) {
979 ret = 0;
980 break;
981 }
982 __remove_assoc_queue(bh);
983 }
984 spin_unlock(&buffer_mapping->private_lock);
985 }
986 return ret;
987}
988
989/*
990 * Create the appropriate buffers when given a page for data area and
991 * the size of each buffer.. Use the bh->b_this_page linked list to
992 * follow the buffers created. Return NULL if unable to create more
993 * buffers.
994 *
995 * The retry flag is used to differentiate async IO (paging, swapping)
996 * which may not fail from ordinary buffer allocations.
997 */
998struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
999 int retry)
1000{
1001 struct buffer_head *bh, *head;
1002 long offset;
1003
1004try_again:
1005 head = NULL;
1006 offset = PAGE_SIZE;
1007 while ((offset -= size) >= 0) {
1008 bh = alloc_buffer_head(GFP_NOFS);
1009 if (!bh)
1010 goto no_grow;
1011
1012 bh->b_bdev = NULL;
1013 bh->b_this_page = head;
1014 bh->b_blocknr = -1;
1015 head = bh;
1016
1017 bh->b_state = 0;
1018 atomic_set(&bh->b_count, 0);
Chris Masonfc5cd582006-02-01 03:06:48 -08001019 bh->b_private = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 bh->b_size = size;
1021
1022 /* Link the buffer to its page */
1023 set_bh_page(bh, page, offset);
1024
Nathan Scott01ffe332006-01-17 09:02:07 +11001025 init_buffer(bh, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001026 }
1027 return head;
1028/*
1029 * In case anything failed, we just free everything we got.
1030 */
1031no_grow:
1032 if (head) {
1033 do {
1034 bh = head;
1035 head = head->b_this_page;
1036 free_buffer_head(bh);
1037 } while (head);
1038 }
1039
1040 /*
1041 * Return failure for non-async IO requests. Async IO requests
1042 * are not allowed to fail, so we have to wait until buffer heads
1043 * become available. But we don't want tasks sleeping with
1044 * partially complete buffers, so all were released above.
1045 */
1046 if (!retry)
1047 return NULL;
1048
1049 /* We're _really_ low on memory. Now we just
1050 * wait for old buffer heads to become free due to
1051 * finishing IO. Since this is an async request and
1052 * the reserve list is empty, we're sure there are
1053 * async buffer heads in use.
1054 */
1055 free_more_memory();
1056 goto try_again;
1057}
1058EXPORT_SYMBOL_GPL(alloc_page_buffers);
1059
1060static inline void
1061link_dev_buffers(struct page *page, struct buffer_head *head)
1062{
1063 struct buffer_head *bh, *tail;
1064
1065 bh = head;
1066 do {
1067 tail = bh;
1068 bh = bh->b_this_page;
1069 } while (bh);
1070 tail->b_this_page = head;
1071 attach_page_buffers(page, head);
1072}
1073
1074/*
1075 * Initialise the state of a blockdev page's buffers.
1076 */
1077static void
1078init_page_buffers(struct page *page, struct block_device *bdev,
1079 sector_t block, int size)
1080{
1081 struct buffer_head *head = page_buffers(page);
1082 struct buffer_head *bh = head;
1083 int uptodate = PageUptodate(page);
1084
1085 do {
1086 if (!buffer_mapped(bh)) {
1087 init_buffer(bh, NULL, NULL);
1088 bh->b_bdev = bdev;
1089 bh->b_blocknr = block;
1090 if (uptodate)
1091 set_buffer_uptodate(bh);
1092 set_buffer_mapped(bh);
1093 }
1094 block++;
1095 bh = bh->b_this_page;
1096 } while (bh != head);
1097}
1098
1099/*
1100 * Create the page-cache page that contains the requested block.
1101 *
1102 * This is user purely for blockdev mappings.
1103 */
1104static struct page *
1105grow_dev_page(struct block_device *bdev, sector_t block,
1106 pgoff_t index, int size)
1107{
1108 struct inode *inode = bdev->bd_inode;
1109 struct page *page;
1110 struct buffer_head *bh;
1111
1112 page = find_or_create_page(inode->i_mapping, index, GFP_NOFS);
1113 if (!page)
1114 return NULL;
1115
Eric Sesterhenne827f922006-03-26 18:24:46 +02001116 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117
1118 if (page_has_buffers(page)) {
1119 bh = page_buffers(page);
1120 if (bh->b_size == size) {
1121 init_page_buffers(page, bdev, block, size);
1122 return page;
1123 }
1124 if (!try_to_free_buffers(page))
1125 goto failed;
1126 }
1127
1128 /*
1129 * Allocate some buffers for this page
1130 */
1131 bh = alloc_page_buffers(page, size, 0);
1132 if (!bh)
1133 goto failed;
1134
1135 /*
1136 * Link the page to the buffers and initialise them. Take the
1137 * lock to be atomic wrt __find_get_block(), which does not
1138 * run under the page lock.
1139 */
1140 spin_lock(&inode->i_mapping->private_lock);
1141 link_dev_buffers(page, bh);
1142 init_page_buffers(page, bdev, block, size);
1143 spin_unlock(&inode->i_mapping->private_lock);
1144 return page;
1145
1146failed:
1147 BUG();
1148 unlock_page(page);
1149 page_cache_release(page);
1150 return NULL;
1151}
1152
1153/*
1154 * Create buffers for the specified block device block's page. If
1155 * that page was dirty, the buffers are set dirty also.
1156 *
1157 * Except that's a bug. Attaching dirty buffers to a dirty
1158 * blockdev's page can result in filesystem corruption, because
1159 * some of those buffers may be aliases of filesystem data.
1160 * grow_dev_page() will go BUG() if this happens.
1161 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001162static int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163grow_buffers(struct block_device *bdev, sector_t block, int size)
1164{
1165 struct page *page;
1166 pgoff_t index;
1167 int sizebits;
1168
1169 sizebits = -1;
1170 do {
1171 sizebits++;
1172 } while ((size << sizebits) < PAGE_SIZE);
1173
1174 index = block >> sizebits;
1175 block = index << sizebits;
1176
1177 /* Create a page with the proper size buffers.. */
1178 page = grow_dev_page(bdev, block, index, size);
1179 if (!page)
1180 return 0;
1181 unlock_page(page);
1182 page_cache_release(page);
1183 return 1;
1184}
1185
Adrian Bunk75c96f82005-05-05 16:16:09 -07001186static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001187__getblk_slow(struct block_device *bdev, sector_t block, int size)
1188{
1189 /* Size must be multiple of hard sectorsize */
1190 if (unlikely(size & (bdev_hardsect_size(bdev)-1) ||
1191 (size < 512 || size > PAGE_SIZE))) {
1192 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1193 size);
1194 printk(KERN_ERR "hardsect size: %d\n",
1195 bdev_hardsect_size(bdev));
1196
1197 dump_stack();
1198 return NULL;
1199 }
1200
1201 for (;;) {
1202 struct buffer_head * bh;
1203
1204 bh = __find_get_block(bdev, block, size);
1205 if (bh)
1206 return bh;
1207
1208 if (!grow_buffers(bdev, block, size))
1209 free_more_memory();
1210 }
1211}
1212
1213/*
1214 * The relationship between dirty buffers and dirty pages:
1215 *
1216 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1217 * the page is tagged dirty in its radix tree.
1218 *
1219 * At all times, the dirtiness of the buffers represents the dirtiness of
1220 * subsections of the page. If the page has buffers, the page dirty bit is
1221 * merely a hint about the true dirty state.
1222 *
1223 * When a page is set dirty in its entirety, all its buffers are marked dirty
1224 * (if the page has buffers).
1225 *
1226 * When a buffer is marked dirty, its page is dirtied, but the page's other
1227 * buffers are not.
1228 *
1229 * Also. When blockdev buffers are explicitly read with bread(), they
1230 * individually become uptodate. But their backing page remains not
1231 * uptodate - even if all of its buffers are uptodate. A subsequent
1232 * block_read_full_page() against that page will discover all the uptodate
1233 * buffers, will set the page uptodate and will perform no I/O.
1234 */
1235
1236/**
1237 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001238 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 *
1240 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1241 * backing page dirty, then tag the page as dirty in its address_space's radix
1242 * tree and then attach the address_space's inode to its superblock's dirty
1243 * inode list.
1244 *
1245 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
1246 * mapping->tree_lock and the global inode_lock.
1247 */
1248void fastcall mark_buffer_dirty(struct buffer_head *bh)
1249{
1250 if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh))
1251 __set_page_dirty_nobuffers(bh->b_page);
1252}
1253
1254/*
1255 * Decrement a buffer_head's reference count. If all buffers against a page
1256 * have zero reference count, are clean and unlocked, and if the page is clean
1257 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1258 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1259 * a page but it ends up not being freed, and buffers may later be reattached).
1260 */
1261void __brelse(struct buffer_head * buf)
1262{
1263 if (atomic_read(&buf->b_count)) {
1264 put_bh(buf);
1265 return;
1266 }
1267 printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n");
1268 WARN_ON(1);
1269}
1270
1271/*
1272 * bforget() is like brelse(), except it discards any
1273 * potentially dirty data.
1274 */
1275void __bforget(struct buffer_head *bh)
1276{
1277 clear_buffer_dirty(bh);
1278 if (!list_empty(&bh->b_assoc_buffers)) {
1279 struct address_space *buffer_mapping = bh->b_page->mapping;
1280
1281 spin_lock(&buffer_mapping->private_lock);
1282 list_del_init(&bh->b_assoc_buffers);
1283 spin_unlock(&buffer_mapping->private_lock);
1284 }
1285 __brelse(bh);
1286}
1287
1288static struct buffer_head *__bread_slow(struct buffer_head *bh)
1289{
1290 lock_buffer(bh);
1291 if (buffer_uptodate(bh)) {
1292 unlock_buffer(bh);
1293 return bh;
1294 } else {
1295 get_bh(bh);
1296 bh->b_end_io = end_buffer_read_sync;
1297 submit_bh(READ, bh);
1298 wait_on_buffer(bh);
1299 if (buffer_uptodate(bh))
1300 return bh;
1301 }
1302 brelse(bh);
1303 return NULL;
1304}
1305
1306/*
1307 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1308 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1309 * refcount elevated by one when they're in an LRU. A buffer can only appear
1310 * once in a particular CPU's LRU. A single buffer can be present in multiple
1311 * CPU's LRUs at the same time.
1312 *
1313 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1314 * sb_find_get_block().
1315 *
1316 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1317 * a local interrupt disable for that.
1318 */
1319
1320#define BH_LRU_SIZE 8
1321
1322struct bh_lru {
1323 struct buffer_head *bhs[BH_LRU_SIZE];
1324};
1325
1326static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1327
1328#ifdef CONFIG_SMP
1329#define bh_lru_lock() local_irq_disable()
1330#define bh_lru_unlock() local_irq_enable()
1331#else
1332#define bh_lru_lock() preempt_disable()
1333#define bh_lru_unlock() preempt_enable()
1334#endif
1335
1336static inline void check_irqs_on(void)
1337{
1338#ifdef irqs_disabled
1339 BUG_ON(irqs_disabled());
1340#endif
1341}
1342
1343/*
1344 * The LRU management algorithm is dopey-but-simple. Sorry.
1345 */
1346static void bh_lru_install(struct buffer_head *bh)
1347{
1348 struct buffer_head *evictee = NULL;
1349 struct bh_lru *lru;
1350
1351 check_irqs_on();
1352 bh_lru_lock();
1353 lru = &__get_cpu_var(bh_lrus);
1354 if (lru->bhs[0] != bh) {
1355 struct buffer_head *bhs[BH_LRU_SIZE];
1356 int in;
1357 int out = 0;
1358
1359 get_bh(bh);
1360 bhs[out++] = bh;
1361 for (in = 0; in < BH_LRU_SIZE; in++) {
1362 struct buffer_head *bh2 = lru->bhs[in];
1363
1364 if (bh2 == bh) {
1365 __brelse(bh2);
1366 } else {
1367 if (out >= BH_LRU_SIZE) {
1368 BUG_ON(evictee != NULL);
1369 evictee = bh2;
1370 } else {
1371 bhs[out++] = bh2;
1372 }
1373 }
1374 }
1375 while (out < BH_LRU_SIZE)
1376 bhs[out++] = NULL;
1377 memcpy(lru->bhs, bhs, sizeof(bhs));
1378 }
1379 bh_lru_unlock();
1380
1381 if (evictee)
1382 __brelse(evictee);
1383}
1384
1385/*
1386 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1387 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001388static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389lookup_bh_lru(struct block_device *bdev, sector_t block, int size)
1390{
1391 struct buffer_head *ret = NULL;
1392 struct bh_lru *lru;
1393 int i;
1394
1395 check_irqs_on();
1396 bh_lru_lock();
1397 lru = &__get_cpu_var(bh_lrus);
1398 for (i = 0; i < BH_LRU_SIZE; i++) {
1399 struct buffer_head *bh = lru->bhs[i];
1400
1401 if (bh && bh->b_bdev == bdev &&
1402 bh->b_blocknr == block && bh->b_size == size) {
1403 if (i) {
1404 while (i) {
1405 lru->bhs[i] = lru->bhs[i - 1];
1406 i--;
1407 }
1408 lru->bhs[0] = bh;
1409 }
1410 get_bh(bh);
1411 ret = bh;
1412 break;
1413 }
1414 }
1415 bh_lru_unlock();
1416 return ret;
1417}
1418
1419/*
1420 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1421 * it in the LRU and mark it as accessed. If it is not present then return
1422 * NULL
1423 */
1424struct buffer_head *
1425__find_get_block(struct block_device *bdev, sector_t block, int size)
1426{
1427 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1428
1429 if (bh == NULL) {
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001430 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 if (bh)
1432 bh_lru_install(bh);
1433 }
1434 if (bh)
1435 touch_buffer(bh);
1436 return bh;
1437}
1438EXPORT_SYMBOL(__find_get_block);
1439
1440/*
1441 * __getblk will locate (and, if necessary, create) the buffer_head
1442 * which corresponds to the passed block_device, block and size. The
1443 * returned buffer has its reference count incremented.
1444 *
1445 * __getblk() cannot fail - it just keeps trying. If you pass it an
1446 * illegal block number, __getblk() will happily return a buffer_head
1447 * which represents the non-existent block. Very weird.
1448 *
1449 * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1450 * attempt is failing. FIXME, perhaps?
1451 */
1452struct buffer_head *
1453__getblk(struct block_device *bdev, sector_t block, int size)
1454{
1455 struct buffer_head *bh = __find_get_block(bdev, block, size);
1456
1457 might_sleep();
1458 if (bh == NULL)
1459 bh = __getblk_slow(bdev, block, size);
1460 return bh;
1461}
1462EXPORT_SYMBOL(__getblk);
1463
1464/*
1465 * Do async read-ahead on a buffer..
1466 */
1467void __breadahead(struct block_device *bdev, sector_t block, int size)
1468{
1469 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001470 if (likely(bh)) {
1471 ll_rw_block(READA, 1, &bh);
1472 brelse(bh);
1473 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474}
1475EXPORT_SYMBOL(__breadahead);
1476
1477/**
1478 * __bread() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001479 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480 * @block: number of block
1481 * @size: size (in bytes) to read
1482 *
1483 * Reads a specified block, and returns buffer head that contains it.
1484 * It returns NULL if the block was unreadable.
1485 */
1486struct buffer_head *
1487__bread(struct block_device *bdev, sector_t block, int size)
1488{
1489 struct buffer_head *bh = __getblk(bdev, block, size);
1490
Andrew Mortona3e713b2005-10-30 15:03:15 -08001491 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 bh = __bread_slow(bh);
1493 return bh;
1494}
1495EXPORT_SYMBOL(__bread);
1496
1497/*
1498 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1499 * This doesn't race because it runs in each cpu either in irq
1500 * or with preempt disabled.
1501 */
1502static void invalidate_bh_lru(void *arg)
1503{
1504 struct bh_lru *b = &get_cpu_var(bh_lrus);
1505 int i;
1506
1507 for (i = 0; i < BH_LRU_SIZE; i++) {
1508 brelse(b->bhs[i]);
1509 b->bhs[i] = NULL;
1510 }
1511 put_cpu_var(bh_lrus);
1512}
1513
1514static void invalidate_bh_lrus(void)
1515{
1516 on_each_cpu(invalidate_bh_lru, NULL, 1, 1);
1517}
1518
1519void set_bh_page(struct buffer_head *bh,
1520 struct page *page, unsigned long offset)
1521{
1522 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001523 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 if (PageHighMem(page))
1525 /*
1526 * This catches illegal uses and preserves the offset:
1527 */
1528 bh->b_data = (char *)(0 + offset);
1529 else
1530 bh->b_data = page_address(page) + offset;
1531}
1532EXPORT_SYMBOL(set_bh_page);
1533
1534/*
1535 * Called when truncating a buffer on a page completely.
1536 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001537static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001538{
1539 lock_buffer(bh);
1540 clear_buffer_dirty(bh);
1541 bh->b_bdev = NULL;
1542 clear_buffer_mapped(bh);
1543 clear_buffer_req(bh);
1544 clear_buffer_new(bh);
1545 clear_buffer_delay(bh);
1546 unlock_buffer(bh);
1547}
1548
1549/**
1550 * try_to_release_page() - release old fs-specific metadata on a page
1551 *
1552 * @page: the page which the kernel is trying to free
1553 * @gfp_mask: memory allocation flags (and I/O mode)
1554 *
1555 * The address_space is to try to release any data against the page
1556 * (presumably at page->private). If the release was successful, return `1'.
1557 * Otherwise return zero.
1558 *
1559 * The @gfp_mask argument specifies whether I/O may be performed to release
1560 * this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
1561 *
1562 * NOTE: @gfp_mask may go away, and this function may become non-blocking.
1563 */
Al Viro27496a82005-10-21 03:20:48 -04001564int try_to_release_page(struct page *page, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565{
1566 struct address_space * const mapping = page->mapping;
1567
1568 BUG_ON(!PageLocked(page));
1569 if (PageWriteback(page))
1570 return 0;
1571
1572 if (mapping && mapping->a_ops->releasepage)
1573 return mapping->a_ops->releasepage(page, gfp_mask);
1574 return try_to_free_buffers(page);
1575}
1576EXPORT_SYMBOL(try_to_release_page);
1577
1578/**
1579 * block_invalidatepage - invalidate part of all of a buffer-backed page
1580 *
1581 * @page: the page which is affected
1582 * @offset: the index of the truncation point
1583 *
1584 * block_invalidatepage() is called when all or part of the page has become
1585 * invalidatedby a truncate operation.
1586 *
1587 * block_invalidatepage() does not have to release all buffers, but it must
1588 * ensure that no dirty buffer is left outside @offset and that no I/O
1589 * is underway against any of the blocks which are outside the truncation
1590 * point. Because the caller is about to free (and possibly reuse) those
1591 * blocks on-disk.
1592 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001593void block_invalidatepage(struct page *page, unsigned long offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594{
1595 struct buffer_head *head, *bh, *next;
1596 unsigned int curr_off = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597
1598 BUG_ON(!PageLocked(page));
1599 if (!page_has_buffers(page))
1600 goto out;
1601
1602 head = page_buffers(page);
1603 bh = head;
1604 do {
1605 unsigned int next_off = curr_off + bh->b_size;
1606 next = bh->b_this_page;
1607
1608 /*
1609 * is this block fully invalidated?
1610 */
1611 if (offset <= curr_off)
1612 discard_buffer(bh);
1613 curr_off = next_off;
1614 bh = next;
1615 } while (bh != head);
1616
1617 /*
1618 * We release buffers only if the entire page is being invalidated.
1619 * The get_block cached value has been unconditionally invalidated,
1620 * so real IO is not possible anymore.
1621 */
1622 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001623 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001625 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626}
1627EXPORT_SYMBOL(block_invalidatepage);
1628
NeilBrown2ff28e22006-03-26 01:37:18 -08001629void do_invalidatepage(struct page *page, unsigned long offset)
Jan Karaaaa40592005-10-30 15:00:16 -08001630{
NeilBrown2ff28e22006-03-26 01:37:18 -08001631 void (*invalidatepage)(struct page *, unsigned long);
1632 invalidatepage = page->mapping->a_ops->invalidatepage ? :
1633 block_invalidatepage;
1634 (*invalidatepage)(page, offset);
Jan Karaaaa40592005-10-30 15:00:16 -08001635}
1636
Linus Torvalds1da177e2005-04-16 15:20:36 -07001637/*
1638 * We attach and possibly dirty the buffers atomically wrt
1639 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1640 * is already excluded via the page lock.
1641 */
1642void create_empty_buffers(struct page *page,
1643 unsigned long blocksize, unsigned long b_state)
1644{
1645 struct buffer_head *bh, *head, *tail;
1646
1647 head = alloc_page_buffers(page, blocksize, 1);
1648 bh = head;
1649 do {
1650 bh->b_state |= b_state;
1651 tail = bh;
1652 bh = bh->b_this_page;
1653 } while (bh);
1654 tail->b_this_page = head;
1655
1656 spin_lock(&page->mapping->private_lock);
1657 if (PageUptodate(page) || PageDirty(page)) {
1658 bh = head;
1659 do {
1660 if (PageDirty(page))
1661 set_buffer_dirty(bh);
1662 if (PageUptodate(page))
1663 set_buffer_uptodate(bh);
1664 bh = bh->b_this_page;
1665 } while (bh != head);
1666 }
1667 attach_page_buffers(page, head);
1668 spin_unlock(&page->mapping->private_lock);
1669}
1670EXPORT_SYMBOL(create_empty_buffers);
1671
1672/*
1673 * We are taking a block for data and we don't want any output from any
1674 * buffer-cache aliases starting from return from that function and
1675 * until the moment when something will explicitly mark the buffer
1676 * dirty (hopefully that will not happen until we will free that block ;-)
1677 * We don't even need to mark it not-uptodate - nobody can expect
1678 * anything from a newly allocated buffer anyway. We used to used
1679 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1680 * don't want to mark the alias unmapped, for example - it would confuse
1681 * anyone who might pick it with bread() afterwards...
1682 *
1683 * Also.. Note that bforget() doesn't lock the buffer. So there can
1684 * be writeout I/O going on against recently-freed buffers. We don't
1685 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1686 * only if we really need to. That happens here.
1687 */
1688void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1689{
1690 struct buffer_head *old_bh;
1691
1692 might_sleep();
1693
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001694 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695 if (old_bh) {
1696 clear_buffer_dirty(old_bh);
1697 wait_on_buffer(old_bh);
1698 clear_buffer_req(old_bh);
1699 __brelse(old_bh);
1700 }
1701}
1702EXPORT_SYMBOL(unmap_underlying_metadata);
1703
1704/*
1705 * NOTE! All mapped/uptodate combinations are valid:
1706 *
1707 * Mapped Uptodate Meaning
1708 *
1709 * No No "unknown" - must do get_block()
1710 * No Yes "hole" - zero-filled
1711 * Yes No "allocated" - allocated on disk, not read in
1712 * Yes Yes "valid" - allocated and up-to-date in memory.
1713 *
1714 * "Dirty" is valid only with the last case (mapped+uptodate).
1715 */
1716
1717/*
1718 * While block_write_full_page is writing back the dirty buffers under
1719 * the page lock, whoever dirtied the buffers may decide to clean them
1720 * again at any time. We handle that by only looking at the buffer
1721 * state inside lock_buffer().
1722 *
1723 * If block_write_full_page() is called for regular writeback
1724 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1725 * locked buffer. This only can happen if someone has written the buffer
1726 * directly, with submit_bh(). At the address_space level PageWriteback
1727 * prevents this contention from occurring.
1728 */
1729static int __block_write_full_page(struct inode *inode, struct page *page,
1730 get_block_t *get_block, struct writeback_control *wbc)
1731{
1732 int err;
1733 sector_t block;
1734 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001735 struct buffer_head *bh, *head;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001736 const unsigned blocksize = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 int nr_underway = 0;
1738
1739 BUG_ON(!PageLocked(page));
1740
1741 last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
1742
1743 if (!page_has_buffers(page)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001744 create_empty_buffers(page, blocksize,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 (1 << BH_Dirty)|(1 << BH_Uptodate));
1746 }
1747
1748 /*
1749 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1750 * here, and the (potentially unmapped) buffers may become dirty at
1751 * any time. If a buffer becomes dirty here after we've inspected it
1752 * then we just miss that fact, and the page stays dirty.
1753 *
1754 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1755 * handle that here by just cleaning them.
1756 */
1757
Andrew Morton54b21a72006-01-08 01:03:05 -08001758 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759 head = page_buffers(page);
1760 bh = head;
1761
1762 /*
1763 * Get all the dirty buffers mapped to disk addresses and
1764 * handle any aliases from the underlying blockdev's mapping.
1765 */
1766 do {
1767 if (block > last_block) {
1768 /*
1769 * mapped buffers outside i_size will occur, because
1770 * this page can be outside i_size when there is a
1771 * truncate in progress.
1772 */
1773 /*
1774 * The buffer was zeroed by block_write_full_page()
1775 */
1776 clear_buffer_dirty(bh);
1777 set_buffer_uptodate(bh);
1778 } else if (!buffer_mapped(bh) && buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001779 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 err = get_block(inode, block, bh, 1);
1781 if (err)
1782 goto recover;
1783 if (buffer_new(bh)) {
1784 /* blockdev mappings never come here */
1785 clear_buffer_new(bh);
1786 unmap_underlying_metadata(bh->b_bdev,
1787 bh->b_blocknr);
1788 }
1789 }
1790 bh = bh->b_this_page;
1791 block++;
1792 } while (bh != head);
1793
1794 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 if (!buffer_mapped(bh))
1796 continue;
1797 /*
1798 * If it's a fully non-blocking write attempt and we cannot
1799 * lock the buffer then redirty the page. Note that this can
1800 * potentially cause a busy-wait loop from pdflush and kswapd
1801 * activity, but those code paths have their own higher-level
1802 * throttling.
1803 */
1804 if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
1805 lock_buffer(bh);
1806 } else if (test_set_buffer_locked(bh)) {
1807 redirty_page_for_writepage(wbc, page);
1808 continue;
1809 }
1810 if (test_clear_buffer_dirty(bh)) {
1811 mark_buffer_async_write(bh);
1812 } else {
1813 unlock_buffer(bh);
1814 }
1815 } while ((bh = bh->b_this_page) != head);
1816
1817 /*
1818 * The page and its buffers are protected by PageWriteback(), so we can
1819 * drop the bh refcounts early.
1820 */
1821 BUG_ON(PageWriteback(page));
1822 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001823
1824 do {
1825 struct buffer_head *next = bh->b_this_page;
1826 if (buffer_async_write(bh)) {
1827 submit_bh(WRITE, bh);
1828 nr_underway++;
1829 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830 bh = next;
1831 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001832 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001833
1834 err = 0;
1835done:
1836 if (nr_underway == 0) {
1837 /*
1838 * The page was marked dirty, but the buffers were
1839 * clean. Someone wrote them back by hand with
1840 * ll_rw_block/submit_bh. A rare case.
1841 */
1842 int uptodate = 1;
1843 do {
1844 if (!buffer_uptodate(bh)) {
1845 uptodate = 0;
1846 break;
1847 }
1848 bh = bh->b_this_page;
1849 } while (bh != head);
1850 if (uptodate)
1851 SetPageUptodate(page);
1852 end_page_writeback(page);
1853 /*
1854 * The page and buffer_heads can be released at any time from
1855 * here on.
1856 */
1857 wbc->pages_skipped++; /* We didn't write this page */
1858 }
1859 return err;
1860
1861recover:
1862 /*
1863 * ENOSPC, or some other error. We may already have added some
1864 * blocks to the file, so we need to write these out to avoid
1865 * exposing stale data.
1866 * The page is currently locked and not marked for writeback
1867 */
1868 bh = head;
1869 /* Recovery: lock and submit the mapped buffers */
1870 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001871 if (buffer_mapped(bh) && buffer_dirty(bh)) {
1872 lock_buffer(bh);
1873 mark_buffer_async_write(bh);
1874 } else {
1875 /*
1876 * The buffer may have been set dirty during
1877 * attachment to a dirty page.
1878 */
1879 clear_buffer_dirty(bh);
1880 }
1881 } while ((bh = bh->b_this_page) != head);
1882 SetPageError(page);
1883 BUG_ON(PageWriteback(page));
1884 set_page_writeback(page);
1885 unlock_page(page);
1886 do {
1887 struct buffer_head *next = bh->b_this_page;
1888 if (buffer_async_write(bh)) {
1889 clear_buffer_dirty(bh);
1890 submit_bh(WRITE, bh);
1891 nr_underway++;
1892 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893 bh = next;
1894 } while (bh != head);
1895 goto done;
1896}
1897
1898static int __block_prepare_write(struct inode *inode, struct page *page,
1899 unsigned from, unsigned to, get_block_t *get_block)
1900{
1901 unsigned block_start, block_end;
1902 sector_t block;
1903 int err = 0;
1904 unsigned blocksize, bbits;
1905 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1906
1907 BUG_ON(!PageLocked(page));
1908 BUG_ON(from > PAGE_CACHE_SIZE);
1909 BUG_ON(to > PAGE_CACHE_SIZE);
1910 BUG_ON(from > to);
1911
1912 blocksize = 1 << inode->i_blkbits;
1913 if (!page_has_buffers(page))
1914 create_empty_buffers(page, blocksize, 0);
1915 head = page_buffers(page);
1916
1917 bbits = inode->i_blkbits;
1918 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1919
1920 for(bh = head, block_start = 0; bh != head || !block_start;
1921 block++, block_start=block_end, bh = bh->b_this_page) {
1922 block_end = block_start + blocksize;
1923 if (block_end <= from || block_start >= to) {
1924 if (PageUptodate(page)) {
1925 if (!buffer_uptodate(bh))
1926 set_buffer_uptodate(bh);
1927 }
1928 continue;
1929 }
1930 if (buffer_new(bh))
1931 clear_buffer_new(bh);
1932 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001933 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 err = get_block(inode, block, bh, 1);
1935 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001936 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938 unmap_underlying_metadata(bh->b_bdev,
1939 bh->b_blocknr);
1940 if (PageUptodate(page)) {
1941 set_buffer_uptodate(bh);
1942 continue;
1943 }
1944 if (block_end > to || block_start < from) {
1945 void *kaddr;
1946
1947 kaddr = kmap_atomic(page, KM_USER0);
1948 if (block_end > to)
1949 memset(kaddr+to, 0,
1950 block_end-to);
1951 if (block_start < from)
1952 memset(kaddr+block_start,
1953 0, from-block_start);
1954 flush_dcache_page(page);
1955 kunmap_atomic(kaddr, KM_USER0);
1956 }
1957 continue;
1958 }
1959 }
1960 if (PageUptodate(page)) {
1961 if (!buffer_uptodate(bh))
1962 set_buffer_uptodate(bh);
1963 continue;
1964 }
1965 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
1966 (block_start < from || block_end > to)) {
1967 ll_rw_block(READ, 1, &bh);
1968 *wait_bh++=bh;
1969 }
1970 }
1971 /*
1972 * If we issued read requests - let them complete.
1973 */
1974 while(wait_bh > wait) {
1975 wait_on_buffer(*--wait_bh);
1976 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001977 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 }
Anton Altaparmakov152becd2005-06-23 00:10:21 -07001979 if (!err) {
1980 bh = head;
1981 do {
1982 if (buffer_new(bh))
1983 clear_buffer_new(bh);
1984 } while ((bh = bh->b_this_page) != head);
1985 return 0;
1986 }
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001987 /* Error case: */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988 /*
1989 * Zero out any newly allocated blocks to avoid exposing stale
1990 * data. If BH_New is set, we know that the block was newly
1991 * allocated in the above loop.
1992 */
1993 bh = head;
1994 block_start = 0;
1995 do {
1996 block_end = block_start+blocksize;
1997 if (block_end <= from)
1998 goto next_bh;
1999 if (block_start >= to)
2000 break;
2001 if (buffer_new(bh)) {
2002 void *kaddr;
2003
2004 clear_buffer_new(bh);
2005 kaddr = kmap_atomic(page, KM_USER0);
2006 memset(kaddr+block_start, 0, bh->b_size);
2007 kunmap_atomic(kaddr, KM_USER0);
2008 set_buffer_uptodate(bh);
2009 mark_buffer_dirty(bh);
2010 }
2011next_bh:
2012 block_start = block_end;
2013 bh = bh->b_this_page;
2014 } while (bh != head);
2015 return err;
2016}
2017
2018static int __block_commit_write(struct inode *inode, struct page *page,
2019 unsigned from, unsigned to)
2020{
2021 unsigned block_start, block_end;
2022 int partial = 0;
2023 unsigned blocksize;
2024 struct buffer_head *bh, *head;
2025
2026 blocksize = 1 << inode->i_blkbits;
2027
2028 for(bh = head = page_buffers(page), block_start = 0;
2029 bh != head || !block_start;
2030 block_start=block_end, bh = bh->b_this_page) {
2031 block_end = block_start + blocksize;
2032 if (block_end <= from || block_start >= to) {
2033 if (!buffer_uptodate(bh))
2034 partial = 1;
2035 } else {
2036 set_buffer_uptodate(bh);
2037 mark_buffer_dirty(bh);
2038 }
2039 }
2040
2041 /*
2042 * If this is a partial write which happened to make all buffers
2043 * uptodate then we can optimize away a bogus readpage() for
2044 * the next read(). Here we 'discover' whether the page went
2045 * uptodate as a result of this (potentially partial) write.
2046 */
2047 if (!partial)
2048 SetPageUptodate(page);
2049 return 0;
2050}
2051
2052/*
2053 * Generic "read page" function for block devices that have the normal
2054 * get_block functionality. This is most of the block device filesystems.
2055 * Reads the page asynchronously --- the unlock_buffer() and
2056 * set/clear_buffer_uptodate() functions propagate buffer state into the
2057 * page struct once IO has completed.
2058 */
2059int block_read_full_page(struct page *page, get_block_t *get_block)
2060{
2061 struct inode *inode = page->mapping->host;
2062 sector_t iblock, lblock;
2063 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
2064 unsigned int blocksize;
2065 int nr, i;
2066 int fully_mapped = 1;
2067
Matt Mackallcd7619d2005-05-01 08:59:01 -07002068 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002069 blocksize = 1 << inode->i_blkbits;
2070 if (!page_has_buffers(page))
2071 create_empty_buffers(page, blocksize, 0);
2072 head = page_buffers(page);
2073
2074 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2075 lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
2076 bh = head;
2077 nr = 0;
2078 i = 0;
2079
2080 do {
2081 if (buffer_uptodate(bh))
2082 continue;
2083
2084 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002085 int err = 0;
2086
Linus Torvalds1da177e2005-04-16 15:20:36 -07002087 fully_mapped = 0;
2088 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002089 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002090 err = get_block(inode, iblock, bh, 0);
2091 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002092 SetPageError(page);
2093 }
2094 if (!buffer_mapped(bh)) {
2095 void *kaddr = kmap_atomic(page, KM_USER0);
2096 memset(kaddr + i * blocksize, 0, blocksize);
2097 flush_dcache_page(page);
2098 kunmap_atomic(kaddr, KM_USER0);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002099 if (!err)
2100 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002101 continue;
2102 }
2103 /*
2104 * get_block() might have updated the buffer
2105 * synchronously
2106 */
2107 if (buffer_uptodate(bh))
2108 continue;
2109 }
2110 arr[nr++] = bh;
2111 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2112
2113 if (fully_mapped)
2114 SetPageMappedToDisk(page);
2115
2116 if (!nr) {
2117 /*
2118 * All buffers are uptodate - we can set the page uptodate
2119 * as well. But not if get_block() returned an error.
2120 */
2121 if (!PageError(page))
2122 SetPageUptodate(page);
2123 unlock_page(page);
2124 return 0;
2125 }
2126
2127 /* Stage two: lock the buffers */
2128 for (i = 0; i < nr; i++) {
2129 bh = arr[i];
2130 lock_buffer(bh);
2131 mark_buffer_async_read(bh);
2132 }
2133
2134 /*
2135 * Stage 3: start the IO. Check for uptodateness
2136 * inside the buffer lock in case another process reading
2137 * the underlying blockdev brought it uptodate (the sct fix).
2138 */
2139 for (i = 0; i < nr; i++) {
2140 bh = arr[i];
2141 if (buffer_uptodate(bh))
2142 end_buffer_async_read(bh, 1);
2143 else
2144 submit_bh(READ, bh);
2145 }
2146 return 0;
2147}
2148
2149/* utility function for filesystems that need to do work on expanding
2150 * truncates. Uses prepare/commit_write to allow the filesystem to
2151 * deal with the hole.
2152 */
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002153static int __generic_cont_expand(struct inode *inode, loff_t size,
2154 pgoff_t index, unsigned int offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002155{
2156 struct address_space *mapping = inode->i_mapping;
2157 struct page *page;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002158 unsigned long limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159 int err;
2160
2161 err = -EFBIG;
2162 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
2163 if (limit != RLIM_INFINITY && size > (loff_t)limit) {
2164 send_sig(SIGXFSZ, current, 0);
2165 goto out;
2166 }
2167 if (size > inode->i_sb->s_maxbytes)
2168 goto out;
2169
Linus Torvalds1da177e2005-04-16 15:20:36 -07002170 err = -ENOMEM;
2171 page = grab_cache_page(mapping, index);
2172 if (!page)
2173 goto out;
2174 err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002175 if (err) {
2176 /*
2177 * ->prepare_write() may have instantiated a few blocks
2178 * outside i_size. Trim these off again.
2179 */
2180 unlock_page(page);
2181 page_cache_release(page);
2182 vmtruncate(inode, inode->i_size);
2183 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002184 }
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002185
2186 err = mapping->a_ops->commit_write(NULL, page, offset, offset);
2187
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188 unlock_page(page);
2189 page_cache_release(page);
2190 if (err > 0)
2191 err = 0;
2192out:
2193 return err;
2194}
2195
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002196int generic_cont_expand(struct inode *inode, loff_t size)
2197{
2198 pgoff_t index;
2199 unsigned int offset;
2200
2201 offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
2202
2203 /* ugh. in prepare/commit_write, if from==to==start of block, we
2204 ** skip the prepare. make sure we never send an offset for the start
2205 ** of a block
2206 */
2207 if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
2208 /* caller must handle this extra byte. */
2209 offset++;
2210 }
2211 index = size >> PAGE_CACHE_SHIFT;
2212
2213 return __generic_cont_expand(inode, size, index, offset);
2214}
2215
2216int generic_cont_expand_simple(struct inode *inode, loff_t size)
2217{
2218 loff_t pos = size - 1;
2219 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
2220 unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
2221
2222 /* prepare/commit_write can handle even if from==to==start of block. */
2223 return __generic_cont_expand(inode, size, index, offset);
2224}
2225
Linus Torvalds1da177e2005-04-16 15:20:36 -07002226/*
2227 * For moronic filesystems that do not allow holes in file.
2228 * We may have to extend the file.
2229 */
2230
2231int cont_prepare_write(struct page *page, unsigned offset,
2232 unsigned to, get_block_t *get_block, loff_t *bytes)
2233{
2234 struct address_space *mapping = page->mapping;
2235 struct inode *inode = mapping->host;
2236 struct page *new_page;
2237 pgoff_t pgpos;
2238 long status;
2239 unsigned zerofrom;
2240 unsigned blocksize = 1 << inode->i_blkbits;
2241 void *kaddr;
2242
2243 while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
2244 status = -ENOMEM;
2245 new_page = grab_cache_page(mapping, pgpos);
2246 if (!new_page)
2247 goto out;
2248 /* we might sleep */
2249 if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
2250 unlock_page(new_page);
2251 page_cache_release(new_page);
2252 continue;
2253 }
2254 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2255 if (zerofrom & (blocksize-1)) {
2256 *bytes |= (blocksize-1);
2257 (*bytes)++;
2258 }
2259 status = __block_prepare_write(inode, new_page, zerofrom,
2260 PAGE_CACHE_SIZE, get_block);
2261 if (status)
2262 goto out_unmap;
2263 kaddr = kmap_atomic(new_page, KM_USER0);
2264 memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom);
2265 flush_dcache_page(new_page);
2266 kunmap_atomic(kaddr, KM_USER0);
2267 generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
2268 unlock_page(new_page);
2269 page_cache_release(new_page);
2270 }
2271
2272 if (page->index < pgpos) {
2273 /* completely inside the area */
2274 zerofrom = offset;
2275 } else {
2276 /* page covers the boundary, find the boundary offset */
2277 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2278
2279 /* if we will expand the thing last block will be filled */
2280 if (to > zerofrom && (zerofrom & (blocksize-1))) {
2281 *bytes |= (blocksize-1);
2282 (*bytes)++;
2283 }
2284
2285 /* starting below the boundary? Nothing to zero out */
2286 if (offset <= zerofrom)
2287 zerofrom = offset;
2288 }
2289 status = __block_prepare_write(inode, page, zerofrom, to, get_block);
2290 if (status)
2291 goto out1;
2292 if (zerofrom < offset) {
2293 kaddr = kmap_atomic(page, KM_USER0);
2294 memset(kaddr+zerofrom, 0, offset-zerofrom);
2295 flush_dcache_page(page);
2296 kunmap_atomic(kaddr, KM_USER0);
2297 __block_commit_write(inode, page, zerofrom, offset);
2298 }
2299 return 0;
2300out1:
2301 ClearPageUptodate(page);
2302 return status;
2303
2304out_unmap:
2305 ClearPageUptodate(new_page);
2306 unlock_page(new_page);
2307 page_cache_release(new_page);
2308out:
2309 return status;
2310}
2311
2312int block_prepare_write(struct page *page, unsigned from, unsigned to,
2313 get_block_t *get_block)
2314{
2315 struct inode *inode = page->mapping->host;
2316 int err = __block_prepare_write(inode, page, from, to, get_block);
2317 if (err)
2318 ClearPageUptodate(page);
2319 return err;
2320}
2321
2322int block_commit_write(struct page *page, unsigned from, unsigned to)
2323{
2324 struct inode *inode = page->mapping->host;
2325 __block_commit_write(inode,page,from,to);
2326 return 0;
2327}
2328
2329int generic_commit_write(struct file *file, struct page *page,
2330 unsigned from, unsigned to)
2331{
2332 struct inode *inode = page->mapping->host;
2333 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2334 __block_commit_write(inode,page,from,to);
2335 /*
2336 * No need to use i_size_read() here, the i_size
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08002337 * cannot change under us because we hold i_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 */
2339 if (pos > inode->i_size) {
2340 i_size_write(inode, pos);
2341 mark_inode_dirty(inode);
2342 }
2343 return 0;
2344}
2345
2346
2347/*
2348 * nobh_prepare_write()'s prereads are special: the buffer_heads are freed
2349 * immediately, while under the page lock. So it needs a special end_io
2350 * handler which does not touch the bh after unlocking it.
2351 *
2352 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
2353 * a race there is benign: unlock_buffer() only use the bh's address for
2354 * hashing after unlocking the buffer, so it doesn't actually touch the bh
2355 * itself.
2356 */
2357static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2358{
2359 if (uptodate) {
2360 set_buffer_uptodate(bh);
2361 } else {
2362 /* This happens, due to failed READA attempts. */
2363 clear_buffer_uptodate(bh);
2364 }
2365 unlock_buffer(bh);
2366}
2367
2368/*
2369 * On entry, the page is fully not uptodate.
2370 * On exit the page is fully uptodate in the areas outside (from,to)
2371 */
2372int nobh_prepare_write(struct page *page, unsigned from, unsigned to,
2373 get_block_t *get_block)
2374{
2375 struct inode *inode = page->mapping->host;
2376 const unsigned blkbits = inode->i_blkbits;
2377 const unsigned blocksize = 1 << blkbits;
2378 struct buffer_head map_bh;
2379 struct buffer_head *read_bh[MAX_BUF_PER_PAGE];
2380 unsigned block_in_page;
2381 unsigned block_start;
2382 sector_t block_in_file;
2383 char *kaddr;
2384 int nr_reads = 0;
2385 int i;
2386 int ret = 0;
2387 int is_mapped_to_disk = 1;
2388 int dirtied_it = 0;
2389
2390 if (PageMappedToDisk(page))
2391 return 0;
2392
2393 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
2394 map_bh.b_page = page;
2395
2396 /*
2397 * We loop across all blocks in the page, whether or not they are
2398 * part of the affected region. This is so we can discover if the
2399 * page is fully mapped-to-disk.
2400 */
2401 for (block_start = 0, block_in_page = 0;
2402 block_start < PAGE_CACHE_SIZE;
2403 block_in_page++, block_start += blocksize) {
2404 unsigned block_end = block_start + blocksize;
2405 int create;
2406
2407 map_bh.b_state = 0;
2408 create = 1;
2409 if (block_start >= to)
2410 create = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002411 map_bh.b_size = blocksize;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002412 ret = get_block(inode, block_in_file + block_in_page,
2413 &map_bh, create);
2414 if (ret)
2415 goto failed;
2416 if (!buffer_mapped(&map_bh))
2417 is_mapped_to_disk = 0;
2418 if (buffer_new(&map_bh))
2419 unmap_underlying_metadata(map_bh.b_bdev,
2420 map_bh.b_blocknr);
2421 if (PageUptodate(page))
2422 continue;
2423 if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) {
2424 kaddr = kmap_atomic(page, KM_USER0);
2425 if (block_start < from) {
2426 memset(kaddr+block_start, 0, from-block_start);
2427 dirtied_it = 1;
2428 }
2429 if (block_end > to) {
2430 memset(kaddr + to, 0, block_end - to);
2431 dirtied_it = 1;
2432 }
2433 flush_dcache_page(page);
2434 kunmap_atomic(kaddr, KM_USER0);
2435 continue;
2436 }
2437 if (buffer_uptodate(&map_bh))
2438 continue; /* reiserfs does this */
2439 if (block_start < from || block_end > to) {
2440 struct buffer_head *bh = alloc_buffer_head(GFP_NOFS);
2441
2442 if (!bh) {
2443 ret = -ENOMEM;
2444 goto failed;
2445 }
2446 bh->b_state = map_bh.b_state;
2447 atomic_set(&bh->b_count, 0);
2448 bh->b_this_page = NULL;
2449 bh->b_page = page;
2450 bh->b_blocknr = map_bh.b_blocknr;
2451 bh->b_size = blocksize;
2452 bh->b_data = (char *)(long)block_start;
2453 bh->b_bdev = map_bh.b_bdev;
2454 bh->b_private = NULL;
2455 read_bh[nr_reads++] = bh;
2456 }
2457 }
2458
2459 if (nr_reads) {
2460 struct buffer_head *bh;
2461
2462 /*
2463 * The page is locked, so these buffers are protected from
2464 * any VM or truncate activity. Hence we don't need to care
2465 * for the buffer_head refcounts.
2466 */
2467 for (i = 0; i < nr_reads; i++) {
2468 bh = read_bh[i];
2469 lock_buffer(bh);
2470 bh->b_end_io = end_buffer_read_nobh;
2471 submit_bh(READ, bh);
2472 }
2473 for (i = 0; i < nr_reads; i++) {
2474 bh = read_bh[i];
2475 wait_on_buffer(bh);
2476 if (!buffer_uptodate(bh))
2477 ret = -EIO;
2478 free_buffer_head(bh);
2479 read_bh[i] = NULL;
2480 }
2481 if (ret)
2482 goto failed;
2483 }
2484
2485 if (is_mapped_to_disk)
2486 SetPageMappedToDisk(page);
2487 SetPageUptodate(page);
2488
2489 /*
2490 * Setting the page dirty here isn't necessary for the prepare_write
2491 * function - commit_write will do that. But if/when this function is
2492 * used within the pagefault handler to ensure that all mmapped pages
2493 * have backing space in the filesystem, we will need to dirty the page
2494 * if its contents were altered.
2495 */
2496 if (dirtied_it)
2497 set_page_dirty(page);
2498
2499 return 0;
2500
2501failed:
2502 for (i = 0; i < nr_reads; i++) {
2503 if (read_bh[i])
2504 free_buffer_head(read_bh[i]);
2505 }
2506
2507 /*
2508 * Error recovery is pretty slack. Clear the page and mark it dirty
2509 * so we'll later zero out any blocks which _were_ allocated.
2510 */
2511 kaddr = kmap_atomic(page, KM_USER0);
2512 memset(kaddr, 0, PAGE_CACHE_SIZE);
2513 kunmap_atomic(kaddr, KM_USER0);
2514 SetPageUptodate(page);
2515 set_page_dirty(page);
2516 return ret;
2517}
2518EXPORT_SYMBOL(nobh_prepare_write);
2519
2520int nobh_commit_write(struct file *file, struct page *page,
2521 unsigned from, unsigned to)
2522{
2523 struct inode *inode = page->mapping->host;
2524 loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
2525
2526 set_page_dirty(page);
2527 if (pos > inode->i_size) {
2528 i_size_write(inode, pos);
2529 mark_inode_dirty(inode);
2530 }
2531 return 0;
2532}
2533EXPORT_SYMBOL(nobh_commit_write);
2534
2535/*
2536 * nobh_writepage() - based on block_full_write_page() except
2537 * that it tries to operate without attaching bufferheads to
2538 * the page.
2539 */
2540int nobh_writepage(struct page *page, get_block_t *get_block,
2541 struct writeback_control *wbc)
2542{
2543 struct inode * const inode = page->mapping->host;
2544 loff_t i_size = i_size_read(inode);
2545 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2546 unsigned offset;
2547 void *kaddr;
2548 int ret;
2549
2550 /* Is the page fully inside i_size? */
2551 if (page->index < end_index)
2552 goto out;
2553
2554 /* Is the page fully outside i_size? (truncate in progress) */
2555 offset = i_size & (PAGE_CACHE_SIZE-1);
2556 if (page->index >= end_index+1 || !offset) {
2557 /*
2558 * The page may have dirty, unmapped buffers. For example,
2559 * they may have been added in ext3_writepage(). Make them
2560 * freeable here, so the page does not leak.
2561 */
2562#if 0
2563 /* Not really sure about this - do we need this ? */
2564 if (page->mapping->a_ops->invalidatepage)
2565 page->mapping->a_ops->invalidatepage(page, offset);
2566#endif
2567 unlock_page(page);
2568 return 0; /* don't care */
2569 }
2570
2571 /*
2572 * The page straddles i_size. It must be zeroed out on each and every
2573 * writepage invocation because it may be mmapped. "A file is mapped
2574 * in multiples of the page size. For a file that is not a multiple of
2575 * the page size, the remaining memory is zeroed when mapped, and
2576 * writes to that region are not written out to the file."
2577 */
2578 kaddr = kmap_atomic(page, KM_USER0);
2579 memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
2580 flush_dcache_page(page);
2581 kunmap_atomic(kaddr, KM_USER0);
2582out:
2583 ret = mpage_writepage(page, get_block, wbc);
2584 if (ret == -EAGAIN)
2585 ret = __block_write_full_page(inode, page, get_block, wbc);
2586 return ret;
2587}
2588EXPORT_SYMBOL(nobh_writepage);
2589
2590/*
2591 * This function assumes that ->prepare_write() uses nobh_prepare_write().
2592 */
2593int nobh_truncate_page(struct address_space *mapping, loff_t from)
2594{
2595 struct inode *inode = mapping->host;
2596 unsigned blocksize = 1 << inode->i_blkbits;
2597 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2598 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2599 unsigned to;
2600 struct page *page;
2601 struct address_space_operations *a_ops = mapping->a_ops;
2602 char *kaddr;
2603 int ret = 0;
2604
2605 if ((offset & (blocksize - 1)) == 0)
2606 goto out;
2607
2608 ret = -ENOMEM;
2609 page = grab_cache_page(mapping, index);
2610 if (!page)
2611 goto out;
2612
2613 to = (offset + blocksize) & ~(blocksize - 1);
2614 ret = a_ops->prepare_write(NULL, page, offset, to);
2615 if (ret == 0) {
2616 kaddr = kmap_atomic(page, KM_USER0);
2617 memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
2618 flush_dcache_page(page);
2619 kunmap_atomic(kaddr, KM_USER0);
2620 set_page_dirty(page);
2621 }
2622 unlock_page(page);
2623 page_cache_release(page);
2624out:
2625 return ret;
2626}
2627EXPORT_SYMBOL(nobh_truncate_page);
2628
2629int block_truncate_page(struct address_space *mapping,
2630 loff_t from, get_block_t *get_block)
2631{
2632 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2633 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2634 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002635 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002636 unsigned length, pos;
2637 struct inode *inode = mapping->host;
2638 struct page *page;
2639 struct buffer_head *bh;
2640 void *kaddr;
2641 int err;
2642
2643 blocksize = 1 << inode->i_blkbits;
2644 length = offset & (blocksize - 1);
2645
2646 /* Block boundary? Nothing to do */
2647 if (!length)
2648 return 0;
2649
2650 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002651 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002652
2653 page = grab_cache_page(mapping, index);
2654 err = -ENOMEM;
2655 if (!page)
2656 goto out;
2657
2658 if (!page_has_buffers(page))
2659 create_empty_buffers(page, blocksize, 0);
2660
2661 /* Find the buffer that contains "offset" */
2662 bh = page_buffers(page);
2663 pos = blocksize;
2664 while (offset >= pos) {
2665 bh = bh->b_this_page;
2666 iblock++;
2667 pos += blocksize;
2668 }
2669
2670 err = 0;
2671 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002672 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673 err = get_block(inode, iblock, bh, 0);
2674 if (err)
2675 goto unlock;
2676 /* unmapped? It's a hole - nothing to do */
2677 if (!buffer_mapped(bh))
2678 goto unlock;
2679 }
2680
2681 /* Ok, it's mapped. Make sure it's up-to-date */
2682 if (PageUptodate(page))
2683 set_buffer_uptodate(bh);
2684
2685 if (!buffer_uptodate(bh) && !buffer_delay(bh)) {
2686 err = -EIO;
2687 ll_rw_block(READ, 1, &bh);
2688 wait_on_buffer(bh);
2689 /* Uhhuh. Read error. Complain and punt. */
2690 if (!buffer_uptodate(bh))
2691 goto unlock;
2692 }
2693
2694 kaddr = kmap_atomic(page, KM_USER0);
2695 memset(kaddr + offset, 0, length);
2696 flush_dcache_page(page);
2697 kunmap_atomic(kaddr, KM_USER0);
2698
2699 mark_buffer_dirty(bh);
2700 err = 0;
2701
2702unlock:
2703 unlock_page(page);
2704 page_cache_release(page);
2705out:
2706 return err;
2707}
2708
2709/*
2710 * The generic ->writepage function for buffer-backed address_spaces
2711 */
2712int block_write_full_page(struct page *page, get_block_t *get_block,
2713 struct writeback_control *wbc)
2714{
2715 struct inode * const inode = page->mapping->host;
2716 loff_t i_size = i_size_read(inode);
2717 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2718 unsigned offset;
2719 void *kaddr;
2720
2721 /* Is the page fully inside i_size? */
2722 if (page->index < end_index)
2723 return __block_write_full_page(inode, page, get_block, wbc);
2724
2725 /* Is the page fully outside i_size? (truncate in progress) */
2726 offset = i_size & (PAGE_CACHE_SIZE-1);
2727 if (page->index >= end_index+1 || !offset) {
2728 /*
2729 * The page may have dirty, unmapped buffers. For example,
2730 * they may have been added in ext3_writepage(). Make them
2731 * freeable here, so the page does not leak.
2732 */
Jan Karaaaa40592005-10-30 15:00:16 -08002733 do_invalidatepage(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734 unlock_page(page);
2735 return 0; /* don't care */
2736 }
2737
2738 /*
2739 * The page straddles i_size. It must be zeroed out on each and every
2740 * writepage invokation because it may be mmapped. "A file is mapped
2741 * in multiples of the page size. For a file that is not a multiple of
2742 * the page size, the remaining memory is zeroed when mapped, and
2743 * writes to that region are not written out to the file."
2744 */
2745 kaddr = kmap_atomic(page, KM_USER0);
2746 memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
2747 flush_dcache_page(page);
2748 kunmap_atomic(kaddr, KM_USER0);
2749 return __block_write_full_page(inode, page, get_block, wbc);
2750}
2751
2752sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2753 get_block_t *get_block)
2754{
2755 struct buffer_head tmp;
2756 struct inode *inode = mapping->host;
2757 tmp.b_state = 0;
2758 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002759 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002760 get_block(inode, block, &tmp, 0);
2761 return tmp.b_blocknr;
2762}
2763
2764static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err)
2765{
2766 struct buffer_head *bh = bio->bi_private;
2767
2768 if (bio->bi_size)
2769 return 1;
2770
2771 if (err == -EOPNOTSUPP) {
2772 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
2773 set_bit(BH_Eopnotsupp, &bh->b_state);
2774 }
2775
2776 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2777 bio_put(bio);
2778 return 0;
2779}
2780
2781int submit_bh(int rw, struct buffer_head * bh)
2782{
2783 struct bio *bio;
2784 int ret = 0;
2785
2786 BUG_ON(!buffer_locked(bh));
2787 BUG_ON(!buffer_mapped(bh));
2788 BUG_ON(!bh->b_end_io);
2789
2790 if (buffer_ordered(bh) && (rw == WRITE))
2791 rw = WRITE_BARRIER;
2792
2793 /*
2794 * Only clear out a write error when rewriting, should this
2795 * include WRITE_SYNC as well?
2796 */
2797 if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER))
2798 clear_buffer_write_io_error(bh);
2799
2800 /*
2801 * from here on down, it's all bio -- do the initial mapping,
2802 * submit_bio -> generic_make_request may further map this bio around
2803 */
2804 bio = bio_alloc(GFP_NOIO, 1);
2805
2806 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
2807 bio->bi_bdev = bh->b_bdev;
2808 bio->bi_io_vec[0].bv_page = bh->b_page;
2809 bio->bi_io_vec[0].bv_len = bh->b_size;
2810 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
2811
2812 bio->bi_vcnt = 1;
2813 bio->bi_idx = 0;
2814 bio->bi_size = bh->b_size;
2815
2816 bio->bi_end_io = end_bio_bh_io_sync;
2817 bio->bi_private = bh;
2818
2819 bio_get(bio);
2820 submit_bio(rw, bio);
2821
2822 if (bio_flagged(bio, BIO_EOPNOTSUPP))
2823 ret = -EOPNOTSUPP;
2824
2825 bio_put(bio);
2826 return ret;
2827}
2828
2829/**
2830 * ll_rw_block: low-level access to block devices (DEPRECATED)
Jan Karaa7662232005-09-06 15:19:10 -07002831 * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002832 * @nr: number of &struct buffer_heads in the array
2833 * @bhs: array of pointers to &struct buffer_head
2834 *
Jan Karaa7662232005-09-06 15:19:10 -07002835 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
2836 * requests an I/O operation on them, either a %READ or a %WRITE. The third
2837 * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
2838 * are sent to disk. The fourth %READA option is described in the documentation
2839 * for generic_make_request() which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002840 *
2841 * This function drops any buffer that it cannot get a lock on (with the
Jan Karaa7662232005-09-06 15:19:10 -07002842 * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
2843 * clean when doing a write request, and any buffer that appears to be
2844 * up-to-date when doing read request. Further it marks as clean buffers that
2845 * are processed for writing (the buffer cache won't assume that they are
2846 * actually clean until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002847 *
2848 * ll_rw_block sets b_end_io to simple completion handler that marks
2849 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
2850 * any waiters.
2851 *
2852 * All of the buffers must be for the same device, and must also be a
2853 * multiple of the current approved size for the device.
2854 */
2855void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
2856{
2857 int i;
2858
2859 for (i = 0; i < nr; i++) {
2860 struct buffer_head *bh = bhs[i];
2861
Jan Karaa7662232005-09-06 15:19:10 -07002862 if (rw == SWRITE)
2863 lock_buffer(bh);
2864 else if (test_set_buffer_locked(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002865 continue;
2866
Jan Karaa7662232005-09-06 15:19:10 -07002867 if (rw == WRITE || rw == SWRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002868 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07002869 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08002870 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002871 submit_bh(WRITE, bh);
2872 continue;
2873 }
2874 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002875 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07002876 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08002877 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002878 submit_bh(rw, bh);
2879 continue;
2880 }
2881 }
2882 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002883 }
2884}
2885
2886/*
2887 * For a data-integrity writeout, we need to wait upon any in-progress I/O
2888 * and then start new I/O and then wait upon it. The caller must have a ref on
2889 * the buffer_head.
2890 */
2891int sync_dirty_buffer(struct buffer_head *bh)
2892{
2893 int ret = 0;
2894
2895 WARN_ON(atomic_read(&bh->b_count) < 1);
2896 lock_buffer(bh);
2897 if (test_clear_buffer_dirty(bh)) {
2898 get_bh(bh);
2899 bh->b_end_io = end_buffer_write_sync;
2900 ret = submit_bh(WRITE, bh);
2901 wait_on_buffer(bh);
2902 if (buffer_eopnotsupp(bh)) {
2903 clear_buffer_eopnotsupp(bh);
2904 ret = -EOPNOTSUPP;
2905 }
2906 if (!ret && !buffer_uptodate(bh))
2907 ret = -EIO;
2908 } else {
2909 unlock_buffer(bh);
2910 }
2911 return ret;
2912}
2913
2914/*
2915 * try_to_free_buffers() checks if all the buffers on this particular page
2916 * are unused, and releases them if so.
2917 *
2918 * Exclusion against try_to_free_buffers may be obtained by either
2919 * locking the page or by holding its mapping's private_lock.
2920 *
2921 * If the page is dirty but all the buffers are clean then we need to
2922 * be sure to mark the page clean as well. This is because the page
2923 * may be against a block device, and a later reattachment of buffers
2924 * to a dirty page will set *all* buffers dirty. Which would corrupt
2925 * filesystem data on the same device.
2926 *
2927 * The same applies to regular filesystem pages: if all the buffers are
2928 * clean then we set the page clean and proceed. To do that, we require
2929 * total exclusion from __set_page_dirty_buffers(). That is obtained with
2930 * private_lock.
2931 *
2932 * try_to_free_buffers() is non-blocking.
2933 */
2934static inline int buffer_busy(struct buffer_head *bh)
2935{
2936 return atomic_read(&bh->b_count) |
2937 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
2938}
2939
2940static int
2941drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
2942{
2943 struct buffer_head *head = page_buffers(page);
2944 struct buffer_head *bh;
2945
2946 bh = head;
2947 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07002948 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002949 set_bit(AS_EIO, &page->mapping->flags);
2950 if (buffer_busy(bh))
2951 goto failed;
2952 bh = bh->b_this_page;
2953 } while (bh != head);
2954
2955 do {
2956 struct buffer_head *next = bh->b_this_page;
2957
2958 if (!list_empty(&bh->b_assoc_buffers))
2959 __remove_assoc_queue(bh);
2960 bh = next;
2961 } while (bh != head);
2962 *buffers_to_free = head;
2963 __clear_page_buffers(page);
2964 return 1;
2965failed:
2966 return 0;
2967}
2968
2969int try_to_free_buffers(struct page *page)
2970{
2971 struct address_space * const mapping = page->mapping;
2972 struct buffer_head *buffers_to_free = NULL;
2973 int ret = 0;
2974
2975 BUG_ON(!PageLocked(page));
2976 if (PageWriteback(page))
2977 return 0;
2978
2979 if (mapping == NULL) { /* can this still happen? */
2980 ret = drop_buffers(page, &buffers_to_free);
2981 goto out;
2982 }
2983
2984 spin_lock(&mapping->private_lock);
2985 ret = drop_buffers(page, &buffers_to_free);
2986 if (ret) {
2987 /*
2988 * If the filesystem writes its buffers by hand (eg ext3)
2989 * then we can have clean buffers against a dirty page. We
2990 * clean the page here; otherwise later reattachment of buffers
2991 * could encounter a non-uptodate page, which is unresolvable.
2992 * This only applies in the rare case where try_to_free_buffers
2993 * succeeds but the page is not freed.
2994 */
2995 clear_page_dirty(page);
2996 }
2997 spin_unlock(&mapping->private_lock);
2998out:
2999 if (buffers_to_free) {
3000 struct buffer_head *bh = buffers_to_free;
3001
3002 do {
3003 struct buffer_head *next = bh->b_this_page;
3004 free_buffer_head(bh);
3005 bh = next;
3006 } while (bh != buffers_to_free);
3007 }
3008 return ret;
3009}
3010EXPORT_SYMBOL(try_to_free_buffers);
3011
NeilBrown3978d7172006-03-26 01:37:17 -08003012void block_sync_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003013{
3014 struct address_space *mapping;
3015
3016 smp_mb();
3017 mapping = page_mapping(page);
3018 if (mapping)
3019 blk_run_backing_dev(mapping->backing_dev_info, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003020}
3021
3022/*
3023 * There are no bdflush tunables left. But distributions are
3024 * still running obsolete flush daemons, so we terminate them here.
3025 *
3026 * Use of bdflush() is deprecated and will be removed in a future kernel.
3027 * The `pdflush' kernel threads fully replace bdflush daemons and this call.
3028 */
3029asmlinkage long sys_bdflush(int func, long data)
3030{
3031 static int msg_count;
3032
3033 if (!capable(CAP_SYS_ADMIN))
3034 return -EPERM;
3035
3036 if (msg_count < 5) {
3037 msg_count++;
3038 printk(KERN_INFO
3039 "warning: process `%s' used the obsolete bdflush"
3040 " system call\n", current->comm);
3041 printk(KERN_INFO "Fix your initscripts?\n");
3042 }
3043
3044 if (func == 1)
3045 do_exit(0);
3046 return 0;
3047}
3048
3049/*
3050 * Buffer-head allocation
3051 */
3052static kmem_cache_t *bh_cachep;
3053
3054/*
3055 * Once the number of bh's in the machine exceeds this level, we start
3056 * stripping them in writeback.
3057 */
3058static int max_buffer_heads;
3059
3060int buffer_heads_over_limit;
3061
3062struct bh_accounting {
3063 int nr; /* Number of live bh's */
3064 int ratelimit; /* Limit cacheline bouncing */
3065};
3066
3067static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3068
3069static void recalc_bh_state(void)
3070{
3071 int i;
3072 int tot = 0;
3073
3074 if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
3075 return;
3076 __get_cpu_var(bh_accounting).ratelimit = 0;
Eric Dumazet8a143422006-03-24 03:18:10 -08003077 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003078 tot += per_cpu(bh_accounting, i).nr;
3079 buffer_heads_over_limit = (tot > max_buffer_heads);
3080}
3081
Al Virodd0fc662005-10-07 07:46:04 +01003082struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003083{
3084 struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags);
3085 if (ret) {
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003086 get_cpu_var(bh_accounting).nr++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003087 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003088 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003089 }
3090 return ret;
3091}
3092EXPORT_SYMBOL(alloc_buffer_head);
3093
3094void free_buffer_head(struct buffer_head *bh)
3095{
3096 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3097 kmem_cache_free(bh_cachep, bh);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003098 get_cpu_var(bh_accounting).nr--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003099 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003100 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003101}
3102EXPORT_SYMBOL(free_buffer_head);
3103
3104static void
3105init_buffer_head(void *data, kmem_cache_t *cachep, unsigned long flags)
3106{
3107 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
3108 SLAB_CTOR_CONSTRUCTOR) {
3109 struct buffer_head * bh = (struct buffer_head *)data;
3110
3111 memset(bh, 0, sizeof(*bh));
3112 INIT_LIST_HEAD(&bh->b_assoc_buffers);
3113 }
3114}
3115
3116#ifdef CONFIG_HOTPLUG_CPU
3117static void buffer_exit_cpu(int cpu)
3118{
3119 int i;
3120 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3121
3122 for (i = 0; i < BH_LRU_SIZE; i++) {
3123 brelse(b->bhs[i]);
3124 b->bhs[i] = NULL;
3125 }
Eric Dumazet8a143422006-03-24 03:18:10 -08003126 get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr;
3127 per_cpu(bh_accounting, cpu).nr = 0;
3128 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003129}
3130
3131static int buffer_cpu_notify(struct notifier_block *self,
3132 unsigned long action, void *hcpu)
3133{
3134 if (action == CPU_DEAD)
3135 buffer_exit_cpu((unsigned long)hcpu);
3136 return NOTIFY_OK;
3137}
3138#endif /* CONFIG_HOTPLUG_CPU */
3139
3140void __init buffer_init(void)
3141{
3142 int nrpages;
3143
3144 bh_cachep = kmem_cache_create("buffer_head",
Paul Jacksonb0196002006-03-24 03:16:09 -08003145 sizeof(struct buffer_head), 0,
3146 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3147 SLAB_MEM_SPREAD),
3148 init_buffer_head,
3149 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003150
3151 /*
3152 * Limit the bh occupancy to 10% of ZONE_NORMAL
3153 */
3154 nrpages = (nr_free_buffer_pages() * 10) / 100;
3155 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3156 hotcpu_notifier(buffer_cpu_notify, 0);
3157}
3158
3159EXPORT_SYMBOL(__bforget);
3160EXPORT_SYMBOL(__brelse);
3161EXPORT_SYMBOL(__wait_on_buffer);
3162EXPORT_SYMBOL(block_commit_write);
3163EXPORT_SYMBOL(block_prepare_write);
3164EXPORT_SYMBOL(block_read_full_page);
3165EXPORT_SYMBOL(block_sync_page);
3166EXPORT_SYMBOL(block_truncate_page);
3167EXPORT_SYMBOL(block_write_full_page);
3168EXPORT_SYMBOL(cont_prepare_write);
3169EXPORT_SYMBOL(end_buffer_async_write);
3170EXPORT_SYMBOL(end_buffer_read_sync);
3171EXPORT_SYMBOL(end_buffer_write_sync);
3172EXPORT_SYMBOL(file_fsync);
3173EXPORT_SYMBOL(fsync_bdev);
3174EXPORT_SYMBOL(generic_block_bmap);
3175EXPORT_SYMBOL(generic_commit_write);
3176EXPORT_SYMBOL(generic_cont_expand);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08003177EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003178EXPORT_SYMBOL(init_buffer);
3179EXPORT_SYMBOL(invalidate_bdev);
3180EXPORT_SYMBOL(ll_rw_block);
3181EXPORT_SYMBOL(mark_buffer_dirty);
3182EXPORT_SYMBOL(submit_bh);
3183EXPORT_SYMBOL(sync_dirty_buffer);
3184EXPORT_SYMBOL(unlock_buffer);