Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/buffer.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 83823 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* |
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> |
29 | #include <linux/blkdev.h> |
30 | #include <linux/file.h> |
31 | #include <linux/quotaops.h> |
32 | #include <linux/highmem.h> |
33 | #include <linux/module.h> |
34 | #include <linux/writeback.h> |
35 | #include <linux/hash.h> |
36 | #include <linux/suspend.h> |
37 | #include <linux/buffer_head.h> |
38 | #include <linux/bio.h> |
39 | #include <linux/notifier.h> |
40 | #include <linux/cpu.h> |
41 | #include <linux/bitops.h> |
42 | #include <linux/mpage.h> |
43 | |
44 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); |
45 | static void invalidate_bh_lrus(void); |
46 | |
47 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) |
48 | |
49 | inline void |
50 | init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) |
51 | { |
52 | bh->b_end_io = handler; |
53 | bh->b_private = private; |
54 | } |
55 | |
56 | static int sync_buffer(void *word) |
57 | { |
58 | struct block_device *bd; |
59 | struct buffer_head *bh |
60 | = container_of(word, struct buffer_head, b_state); |
61 | |
62 | smp_mb(); |
63 | bd = bh->b_bdev; |
64 | if (bd) |
65 | blk_run_address_space(bd->bd_inode->i_mapping); |
66 | io_schedule(); |
67 | return 0; |
68 | } |
69 | |
70 | void fastcall __lock_buffer(struct buffer_head *bh) |
71 | { |
72 | wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, |
73 | TASK_UNINTERRUPTIBLE); |
74 | } |
75 | EXPORT_SYMBOL(__lock_buffer); |
76 | |
77 | void fastcall unlock_buffer(struct buffer_head *bh) |
78 | { |
79 | clear_buffer_locked(bh); |
80 | smp_mb__after_clear_bit(); |
81 | wake_up_bit(&bh->b_state, BH_Lock); |
82 | } |
83 | |
84 | /* |
85 | * Block until a buffer comes unlocked. This doesn't stop it |
86 | * from becoming locked again - you have to lock it yourself |
87 | * if you want to preserve its state. |
88 | */ |
89 | void __wait_on_buffer(struct buffer_head * bh) |
90 | { |
91 | wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); |
92 | } |
93 | |
94 | static void |
95 | __clear_page_buffers(struct page *page) |
96 | { |
97 | ClearPagePrivate(page); |
98 | page->private = 0; |
99 | page_cache_release(page); |
100 | } |
101 | |
102 | static void buffer_io_error(struct buffer_head *bh) |
103 | { |
104 | char b[BDEVNAME_SIZE]; |
105 | |
106 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", |
107 | bdevname(bh->b_bdev, b), |
108 | (unsigned long long)bh->b_blocknr); |
109 | } |
110 | |
111 | /* |
112 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and |
113 | * unlock the buffer. This is what ll_rw_block uses too. |
114 | */ |
115 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) |
116 | { |
117 | if (uptodate) { |
118 | set_buffer_uptodate(bh); |
119 | } else { |
120 | /* This happens, due to failed READA attempts. */ |
121 | clear_buffer_uptodate(bh); |
122 | } |
123 | unlock_buffer(bh); |
124 | put_bh(bh); |
125 | } |
126 | |
127 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) |
128 | { |
129 | char b[BDEVNAME_SIZE]; |
130 | |
131 | if (uptodate) { |
132 | set_buffer_uptodate(bh); |
133 | } else { |
134 | if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { |
135 | buffer_io_error(bh); |
136 | printk(KERN_WARNING "lost page write due to " |
137 | "I/O error on %s\n", |
138 | bdevname(bh->b_bdev, b)); |
139 | } |
140 | set_buffer_write_io_error(bh); |
141 | clear_buffer_uptodate(bh); |
142 | } |
143 | unlock_buffer(bh); |
144 | put_bh(bh); |
145 | } |
146 | |
147 | /* |
148 | * Write out and wait upon all the dirty data associated with a block |
149 | * device via its mapping. Does not take the superblock lock. |
150 | */ |
151 | int sync_blockdev(struct block_device *bdev) |
152 | { |
153 | int ret = 0; |
154 | |
155 | if (bdev) { |
156 | int err; |
157 | |
158 | ret = filemap_fdatawrite(bdev->bd_inode->i_mapping); |
159 | err = filemap_fdatawait(bdev->bd_inode->i_mapping); |
160 | if (!ret) |
161 | ret = err; |
162 | } |
163 | return ret; |
164 | } |
165 | EXPORT_SYMBOL(sync_blockdev); |
166 | |
167 | /* |
168 | * Write out and wait upon all dirty data associated with this |
169 | * superblock. Filesystem data as well as the underlying block |
170 | * device. Takes the superblock lock. |
171 | */ |
172 | int fsync_super(struct super_block *sb) |
173 | { |
174 | sync_inodes_sb(sb, 0); |
175 | DQUOT_SYNC(sb); |
176 | lock_super(sb); |
177 | if (sb->s_dirt && sb->s_op->write_super) |
178 | sb->s_op->write_super(sb); |
179 | unlock_super(sb); |
180 | if (sb->s_op->sync_fs) |
181 | sb->s_op->sync_fs(sb, 1); |
182 | sync_blockdev(sb->s_bdev); |
183 | sync_inodes_sb(sb, 1); |
184 | |
185 | 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 | */ |
193 | int 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 | * |
208 | * This takes the block device bd_mount_sem to make sure no new mounts |
209 | * 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 | */ |
213 | struct super_block *freeze_bdev(struct block_device *bdev) |
214 | { |
215 | struct super_block *sb; |
216 | |
217 | down(&bdev->bd_mount_sem); |
218 | sb = get_super(bdev); |
219 | if (sb && !(sb->s_flags & MS_RDONLY)) { |
220 | sb->s_frozen = SB_FREEZE_WRITE; |
221 | smp_wmb(); |
222 | |
223 | sync_inodes_sb(sb, 0); |
224 | DQUOT_SYNC(sb); |
225 | |
226 | lock_super(sb); |
227 | if (sb->s_dirt && sb->s_op->write_super) |
228 | sb->s_op->write_super(sb); |
229 | unlock_super(sb); |
230 | |
231 | if (sb->s_op->sync_fs) |
232 | sb->s_op->sync_fs(sb, 1); |
233 | |
234 | sync_blockdev(sb->s_bdev); |
235 | sync_inodes_sb(sb, 1); |
236 | |
237 | sb->s_frozen = SB_FREEZE_TRANS; |
238 | smp_wmb(); |
239 | |
240 | sync_blockdev(sb->s_bdev); |
241 | |
242 | if (sb->s_op->write_super_lockfs) |
243 | sb->s_op->write_super_lockfs(sb); |
244 | } |
245 | |
246 | sync_blockdev(bdev); |
247 | return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ |
248 | } |
249 | EXPORT_SYMBOL(freeze_bdev); |
250 | |
251 | /** |
252 | * thaw_bdev -- unlock filesystem |
253 | * @bdev: blockdevice to unlock |
254 | * @sb: associated superblock |
255 | * |
256 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). |
257 | */ |
258 | void thaw_bdev(struct block_device *bdev, struct super_block *sb) |
259 | { |
260 | if (sb) { |
261 | BUG_ON(sb->s_bdev != bdev); |
262 | |
263 | if (sb->s_op->unlockfs) |
264 | sb->s_op->unlockfs(sb); |
265 | sb->s_frozen = SB_UNFROZEN; |
266 | smp_wmb(); |
267 | wake_up(&sb->s_wait_unfrozen); |
268 | drop_super(sb); |
269 | } |
270 | |
271 | up(&bdev->bd_mount_sem); |
272 | } |
273 | EXPORT_SYMBOL(thaw_bdev); |
274 | |
275 | /* |
276 | * sync everything. Start out by waking pdflush, because that writes back |
277 | * all queues in parallel. |
278 | */ |
279 | static void do_sync(unsigned long wait) |
280 | { |
281 | wakeup_bdflush(0); |
282 | sync_inodes(0); /* All mappings, inodes and their blockdevs */ |
283 | DQUOT_SYNC(NULL); |
284 | sync_supers(); /* Write the superblocks */ |
285 | sync_filesystems(0); /* Start syncing the filesystems */ |
286 | sync_filesystems(wait); /* Waitingly sync the filesystems */ |
287 | sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */ |
288 | if (!wait) |
289 | printk("Emergency Sync complete\n"); |
290 | if (unlikely(laptop_mode)) |
291 | laptop_sync_completion(); |
292 | } |
293 | |
294 | asmlinkage long sys_sync(void) |
295 | { |
296 | do_sync(1); |
297 | return 0; |
298 | } |
299 | |
300 | void emergency_sync(void) |
301 | { |
302 | pdflush_operation(do_sync, 0); |
303 | } |
304 | |
305 | /* |
306 | * Generic function to fsync a file. |
307 | * |
308 | * filp may be NULL if called via the msync of a vma. |
309 | */ |
310 | |
311 | int file_fsync(struct file *filp, struct dentry *dentry, int datasync) |
312 | { |
313 | struct inode * inode = dentry->d_inode; |
314 | struct super_block * sb; |
315 | int ret, err; |
316 | |
317 | /* sync the inode to buffers */ |
318 | ret = write_inode_now(inode, 0); |
319 | |
320 | /* sync the superblock to buffers */ |
321 | sb = inode->i_sb; |
322 | lock_super(sb); |
323 | if (sb->s_op->write_super) |
324 | sb->s_op->write_super(sb); |
325 | unlock_super(sb); |
326 | |
327 | /* .. finally sync the buffers to disk */ |
328 | err = sync_blockdev(sb->s_bdev); |
329 | if (!ret) |
330 | ret = err; |
331 | return ret; |
332 | } |
333 | |
334 | asmlinkage long sys_fsync(unsigned int fd) |
335 | { |
336 | struct file * file; |
337 | struct address_space *mapping; |
338 | int ret, err; |
339 | |
340 | ret = -EBADF; |
341 | file = fget(fd); |
342 | if (!file) |
343 | goto out; |
344 | |
345 | mapping = file->f_mapping; |
346 | |
347 | ret = -EINVAL; |
348 | if (!file->f_op || !file->f_op->fsync) { |
349 | /* Why? We can still call filemap_fdatawrite */ |
350 | goto out_putf; |
351 | } |
352 | |
353 | current->flags |= PF_SYNCWRITE; |
354 | ret = filemap_fdatawrite(mapping); |
355 | |
356 | /* |
357 | * We need to protect against concurrent writers, |
358 | * which could cause livelocks in fsync_buffers_list |
359 | */ |
360 | down(&mapping->host->i_sem); |
361 | err = file->f_op->fsync(file, file->f_dentry, 0); |
362 | if (!ret) |
363 | ret = err; |
364 | up(&mapping->host->i_sem); |
365 | err = filemap_fdatawait(mapping); |
366 | if (!ret) |
367 | ret = err; |
368 | current->flags &= ~PF_SYNCWRITE; |
369 | |
370 | out_putf: |
371 | fput(file); |
372 | out: |
373 | return ret; |
374 | } |
375 | |
376 | asmlinkage long sys_fdatasync(unsigned int fd) |
377 | { |
378 | struct file * file; |
379 | struct address_space *mapping; |
380 | int ret, err; |
381 | |
382 | ret = -EBADF; |
383 | file = fget(fd); |
384 | if (!file) |
385 | goto out; |
386 | |
387 | ret = -EINVAL; |
388 | if (!file->f_op || !file->f_op->fsync) |
389 | goto out_putf; |
390 | |
391 | mapping = file->f_mapping; |
392 | |
393 | current->flags |= PF_SYNCWRITE; |
394 | ret = filemap_fdatawrite(mapping); |
395 | down(&mapping->host->i_sem); |
396 | err = file->f_op->fsync(file, file->f_dentry, 1); |
397 | if (!ret) |
398 | ret = err; |
399 | up(&mapping->host->i_sem); |
400 | err = filemap_fdatawait(mapping); |
401 | if (!ret) |
402 | ret = err; |
403 | current->flags &= ~PF_SYNCWRITE; |
404 | |
405 | out_putf: |
406 | fput(file); |
407 | out: |
408 | return ret; |
409 | } |
410 | |
411 | /* |
412 | * Various filesystems appear to want __find_get_block to be non-blocking. |
413 | * But it's the page lock which protects the buffers. To get around this, |
414 | * we get exclusion from try_to_free_buffers with the blockdev mapping's |
415 | * private_lock. |
416 | * |
417 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention |
418 | * may be quite high. This code could TryLock the page, and if that |
419 | * succeeds, there is no need to take private_lock. (But if |
420 | * private_lock is contended then so is mapping->tree_lock). |
421 | */ |
422 | static struct buffer_head * |
423 | __find_get_block_slow(struct block_device *bdev, sector_t block, int unused) |
424 | { |
425 | struct inode *bd_inode = bdev->bd_inode; |
426 | struct address_space *bd_mapping = bd_inode->i_mapping; |
427 | struct buffer_head *ret = NULL; |
428 | pgoff_t index; |
429 | struct buffer_head *bh; |
430 | struct buffer_head *head; |
431 | struct page *page; |
432 | int all_mapped = 1; |
433 | |
434 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); |
435 | page = find_get_page(bd_mapping, index); |
436 | if (!page) |
437 | goto out; |
438 | |
439 | spin_lock(&bd_mapping->private_lock); |
440 | if (!page_has_buffers(page)) |
441 | goto out_unlock; |
442 | head = page_buffers(page); |
443 | bh = head; |
444 | do { |
445 | if (bh->b_blocknr == block) { |
446 | ret = bh; |
447 | get_bh(bh); |
448 | goto out_unlock; |
449 | } |
450 | if (!buffer_mapped(bh)) |
451 | all_mapped = 0; |
452 | bh = bh->b_this_page; |
453 | } while (bh != head); |
454 | |
455 | /* we might be here because some of the buffers on this page are |
456 | * not mapped. This is due to various races between |
457 | * file io on the block device and getblk. It gets dealt with |
458 | * elsewhere, don't buffer_error if we had some unmapped buffers |
459 | */ |
460 | if (all_mapped) { |
461 | printk("__find_get_block_slow() failed. " |
462 | "block=%llu, b_blocknr=%llu\n", |
463 | (unsigned long long)block, (unsigned long long)bh->b_blocknr); |
464 | printk("b_state=0x%08lx, b_size=%u\n", bh->b_state, bh->b_size); |
465 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
466 | } |
467 | out_unlock: |
468 | spin_unlock(&bd_mapping->private_lock); |
469 | page_cache_release(page); |
470 | out: |
471 | return ret; |
472 | } |
473 | |
474 | /* If invalidate_buffers() will trash dirty buffers, it means some kind |
475 | of fs corruption is going on. Trashing dirty data always imply losing |
476 | information that was supposed to be just stored on the physical layer |
477 | by the user. |
478 | |
479 | Thus invalidate_buffers in general usage is not allwowed to trash |
480 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to |
481 | be preserved. These buffers are simply skipped. |
482 | |
483 | We also skip buffers which are still in use. For example this can |
484 | happen if a userspace program is reading the block device. |
485 | |
486 | NOTE: In the case where the user removed a removable-media-disk even if |
487 | there's still dirty data not synced on disk (due a bug in the device driver |
488 | or due an error of the user), by not destroying the dirty buffers we could |
489 | generate corruption also on the next media inserted, thus a parameter is |
490 | necessary to handle this case in the most safe way possible (trying |
491 | to not corrupt also the new disk inserted with the data belonging to |
492 | the old now corrupted disk). Also for the ramdisk the natural thing |
493 | to do in order to release the ramdisk memory is to destroy dirty buffers. |
494 | |
495 | These are two special cases. Normal usage imply the device driver |
496 | to issue a sync on the device (without waiting I/O completion) and |
497 | then an invalidate_buffers call that doesn't trash dirty buffers. |
498 | |
499 | For handling cache coherency with the blkdev pagecache the 'update' case |
500 | is been introduced. It is needed to re-read from disk any pinned |
501 | buffer. NOTE: re-reading from disk is destructive so we can do it only |
502 | when we assume nobody is changing the buffercache under our I/O and when |
503 | we think the disk contains more recent information than the buffercache. |
504 | The update == 1 pass marks the buffers we need to update, the update == 2 |
505 | pass does the actual I/O. */ |
506 | void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) |
507 | { |
508 | invalidate_bh_lrus(); |
509 | /* |
510 | * FIXME: what about destroy_dirty_buffers? |
511 | * We really want to use invalidate_inode_pages2() for |
512 | * that, but not until that's cleaned up. |
513 | */ |
514 | invalidate_inode_pages(bdev->bd_inode->i_mapping); |
515 | } |
516 | |
517 | /* |
518 | * Kick pdflush then try to free up some ZONE_NORMAL memory. |
519 | */ |
520 | static void free_more_memory(void) |
521 | { |
522 | struct zone **zones; |
523 | pg_data_t *pgdat; |
524 | |
525 | wakeup_bdflush(1024); |
526 | yield(); |
527 | |
528 | for_each_pgdat(pgdat) { |
529 | zones = pgdat->node_zonelists[GFP_NOFS&GFP_ZONEMASK].zones; |
530 | if (*zones) |
531 | try_to_free_pages(zones, GFP_NOFS, 0); |
532 | } |
533 | } |
534 | |
535 | /* |
536 | * I/O completion handler for block_read_full_page() - pages |
537 | * which come unlocked at the end of I/O. |
538 | */ |
539 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) |
540 | { |
541 | static DEFINE_SPINLOCK(page_uptodate_lock); |
542 | unsigned long flags; |
543 | struct buffer_head *tmp; |
544 | struct page *page; |
545 | int page_uptodate = 1; |
546 | |
547 | BUG_ON(!buffer_async_read(bh)); |
548 | |
549 | page = bh->b_page; |
550 | if (uptodate) { |
551 | set_buffer_uptodate(bh); |
552 | } else { |
553 | clear_buffer_uptodate(bh); |
554 | if (printk_ratelimit()) |
555 | buffer_io_error(bh); |
556 | SetPageError(page); |
557 | } |
558 | |
559 | /* |
560 | * Be _very_ careful from here on. Bad things can happen if |
561 | * two buffer heads end IO at almost the same time and both |
562 | * decide that the page is now completely done. |
563 | */ |
564 | spin_lock_irqsave(&page_uptodate_lock, flags); |
565 | clear_buffer_async_read(bh); |
566 | unlock_buffer(bh); |
567 | tmp = bh; |
568 | do { |
569 | if (!buffer_uptodate(tmp)) |
570 | page_uptodate = 0; |
571 | if (buffer_async_read(tmp)) { |
572 | BUG_ON(!buffer_locked(tmp)); |
573 | goto still_busy; |
574 | } |
575 | tmp = tmp->b_this_page; |
576 | } while (tmp != bh); |
577 | spin_unlock_irqrestore(&page_uptodate_lock, flags); |
578 | |
579 | /* |
580 | * If none of the buffers had errors and they are all |
581 | * uptodate then we can set the page uptodate. |
582 | */ |
583 | if (page_uptodate && !PageError(page)) |
584 | SetPageUptodate(page); |
585 | unlock_page(page); |
586 | return; |
587 | |
588 | still_busy: |
589 | spin_unlock_irqrestore(&page_uptodate_lock, flags); |
590 | return; |
591 | } |
592 | |
593 | /* |
594 | * Completion handler for block_write_full_page() - pages which are unlocked |
595 | * during I/O, and which have PageWriteback cleared upon I/O completion. |
596 | */ |
597 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
598 | { |
599 | char b[BDEVNAME_SIZE]; |
600 | static DEFINE_SPINLOCK(page_uptodate_lock); |
601 | unsigned long flags; |
602 | struct buffer_head *tmp; |
603 | struct page *page; |
604 | |
605 | BUG_ON(!buffer_async_write(bh)); |
606 | |
607 | page = bh->b_page; |
608 | if (uptodate) { |
609 | set_buffer_uptodate(bh); |
610 | } else { |
611 | if (printk_ratelimit()) { |
612 | buffer_io_error(bh); |
613 | printk(KERN_WARNING "lost page write due to " |
614 | "I/O error on %s\n", |
615 | bdevname(bh->b_bdev, b)); |
616 | } |
617 | set_bit(AS_EIO, &page->mapping->flags); |
618 | clear_buffer_uptodate(bh); |
619 | SetPageError(page); |
620 | } |
621 | |
622 | spin_lock_irqsave(&page_uptodate_lock, flags); |
623 | clear_buffer_async_write(bh); |
624 | unlock_buffer(bh); |
625 | tmp = bh->b_this_page; |
626 | while (tmp != bh) { |
627 | if (buffer_async_write(tmp)) { |
628 | BUG_ON(!buffer_locked(tmp)); |
629 | goto still_busy; |
630 | } |
631 | tmp = tmp->b_this_page; |
632 | } |
633 | spin_unlock_irqrestore(&page_uptodate_lock, flags); |
634 | end_page_writeback(page); |
635 | return; |
636 | |
637 | still_busy: |
638 | spin_unlock_irqrestore(&page_uptodate_lock, flags); |
639 | return; |
640 | } |
641 | |
642 | /* |
643 | * If a page's buffers are under async readin (end_buffer_async_read |
644 | * completion) then there is a possibility that another thread of |
645 | * control could lock one of the buffers after it has completed |
646 | * but while some of the other buffers have not completed. This |
647 | * locked buffer would confuse end_buffer_async_read() into not unlocking |
648 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() |
649 | * that this buffer is not under async I/O. |
650 | * |
651 | * The page comes unlocked when it has no locked buffer_async buffers |
652 | * left. |
653 | * |
654 | * PageLocked prevents anyone starting new async I/O reads any of |
655 | * the buffers. |
656 | * |
657 | * PageWriteback is used to prevent simultaneous writeout of the same |
658 | * page. |
659 | * |
660 | * PageLocked prevents anyone from starting writeback of a page which is |
661 | * under read I/O (PageWriteback is only ever set against a locked page). |
662 | */ |
663 | static void mark_buffer_async_read(struct buffer_head *bh) |
664 | { |
665 | bh->b_end_io = end_buffer_async_read; |
666 | set_buffer_async_read(bh); |
667 | } |
668 | |
669 | void mark_buffer_async_write(struct buffer_head *bh) |
670 | { |
671 | bh->b_end_io = end_buffer_async_write; |
672 | set_buffer_async_write(bh); |
673 | } |
674 | EXPORT_SYMBOL(mark_buffer_async_write); |
675 | |
676 | |
677 | /* |
678 | * fs/buffer.c contains helper functions for buffer-backed address space's |
679 | * fsync functions. A common requirement for buffer-based filesystems is |
680 | * that certain data from the backing blockdev needs to be written out for |
681 | * a successful fsync(). For example, ext2 indirect blocks need to be |
682 | * written back and waited upon before fsync() returns. |
683 | * |
684 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), |
685 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the |
686 | * management of a list of dependent buffers at ->i_mapping->private_list. |
687 | * |
688 | * Locking is a little subtle: try_to_free_buffers() will remove buffers |
689 | * from their controlling inode's queue when they are being freed. But |
690 | * try_to_free_buffers() will be operating against the *blockdev* mapping |
691 | * at the time, not against the S_ISREG file which depends on those buffers. |
692 | * So the locking for private_list is via the private_lock in the address_space |
693 | * which backs the buffers. Which is different from the address_space |
694 | * against which the buffers are listed. So for a particular address_space, |
695 | * mapping->private_lock does *not* protect mapping->private_list! In fact, |
696 | * mapping->private_list will always be protected by the backing blockdev's |
697 | * ->private_lock. |
698 | * |
699 | * Which introduces a requirement: all buffers on an address_space's |
700 | * ->private_list must be from the same address_space: the blockdev's. |
701 | * |
702 | * address_spaces which do not place buffers at ->private_list via these |
703 | * utility functions are free to use private_lock and private_list for |
704 | * whatever they want. The only requirement is that list_empty(private_list) |
705 | * be true at clear_inode() time. |
706 | * |
707 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The |
708 | * filesystems should do that. invalidate_inode_buffers() should just go |
709 | * BUG_ON(!list_empty). |
710 | * |
711 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should |
712 | * take an address_space, not an inode. And it should be called |
713 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being |
714 | * queued up. |
715 | * |
716 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the |
717 | * list if it is already on a list. Because if the buffer is on a list, |
718 | * it *must* already be on the right one. If not, the filesystem is being |
719 | * silly. This will save a ton of locking. But first we have to ensure |
720 | * that buffers are taken *off* the old inode's list when they are freed |
721 | * (presumably in truncate). That requires careful auditing of all |
722 | * filesystems (do it inside bforget()). It could also be done by bringing |
723 | * b_inode back. |
724 | */ |
725 | |
726 | /* |
727 | * The buffer's backing address_space's private_lock must be held |
728 | */ |
729 | static inline void __remove_assoc_queue(struct buffer_head *bh) |
730 | { |
731 | list_del_init(&bh->b_assoc_buffers); |
732 | } |
733 | |
734 | int inode_has_buffers(struct inode *inode) |
735 | { |
736 | return !list_empty(&inode->i_data.private_list); |
737 | } |
738 | |
739 | /* |
740 | * osync is designed to support O_SYNC io. It waits synchronously for |
741 | * all already-submitted IO to complete, but does not queue any new |
742 | * writes to the disk. |
743 | * |
744 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as |
745 | * you dirty the buffers, and then use osync_inode_buffers to wait for |
746 | * completion. Any other dirty buffers which are not yet queued for |
747 | * write will not be flushed to disk by the osync. |
748 | */ |
749 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) |
750 | { |
751 | struct buffer_head *bh; |
752 | struct list_head *p; |
753 | int err = 0; |
754 | |
755 | spin_lock(lock); |
756 | repeat: |
757 | list_for_each_prev(p, list) { |
758 | bh = BH_ENTRY(p); |
759 | if (buffer_locked(bh)) { |
760 | get_bh(bh); |
761 | spin_unlock(lock); |
762 | wait_on_buffer(bh); |
763 | if (!buffer_uptodate(bh)) |
764 | err = -EIO; |
765 | brelse(bh); |
766 | spin_lock(lock); |
767 | goto repeat; |
768 | } |
769 | } |
770 | spin_unlock(lock); |
771 | return err; |
772 | } |
773 | |
774 | /** |
775 | * sync_mapping_buffers - write out and wait upon a mapping's "associated" |
776 | * buffers |
777 | * @mapping: the mapping which wants those buffers written |
778 | * |
779 | * Starts I/O against the buffers at mapping->private_list, and waits upon |
780 | * that I/O. |
781 | * |
782 | * Basically, this is a convenience function for fsync(). |
783 | * @mapping is a file or directory which needs those buffers to be written for |
784 | * a successful fsync(). |
785 | */ |
786 | int sync_mapping_buffers(struct address_space *mapping) |
787 | { |
788 | struct address_space *buffer_mapping = mapping->assoc_mapping; |
789 | |
790 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) |
791 | return 0; |
792 | |
793 | return fsync_buffers_list(&buffer_mapping->private_lock, |
794 | &mapping->private_list); |
795 | } |
796 | EXPORT_SYMBOL(sync_mapping_buffers); |
797 | |
798 | /* |
799 | * Called when we've recently written block `bblock', and it is known that |
800 | * `bblock' was for a buffer_boundary() buffer. This means that the block at |
801 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's |
802 | * dirty, schedule it for IO. So that indirects merge nicely with their data. |
803 | */ |
804 | void write_boundary_block(struct block_device *bdev, |
805 | sector_t bblock, unsigned blocksize) |
806 | { |
807 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); |
808 | if (bh) { |
809 | if (buffer_dirty(bh)) |
810 | ll_rw_block(WRITE, 1, &bh); |
811 | put_bh(bh); |
812 | } |
813 | } |
814 | |
815 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) |
816 | { |
817 | struct address_space *mapping = inode->i_mapping; |
818 | struct address_space *buffer_mapping = bh->b_page->mapping; |
819 | |
820 | mark_buffer_dirty(bh); |
821 | if (!mapping->assoc_mapping) { |
822 | mapping->assoc_mapping = buffer_mapping; |
823 | } else { |
824 | if (mapping->assoc_mapping != buffer_mapping) |
825 | BUG(); |
826 | } |
827 | if (list_empty(&bh->b_assoc_buffers)) { |
828 | spin_lock(&buffer_mapping->private_lock); |
829 | list_move_tail(&bh->b_assoc_buffers, |
830 | &mapping->private_list); |
831 | spin_unlock(&buffer_mapping->private_lock); |
832 | } |
833 | } |
834 | EXPORT_SYMBOL(mark_buffer_dirty_inode); |
835 | |
836 | /* |
837 | * Add a page to the dirty page list. |
838 | * |
839 | * It is a sad fact of life that this function is called from several places |
840 | * deeply under spinlocking. It may not sleep. |
841 | * |
842 | * If the page has buffers, the uptodate buffers are set dirty, to preserve |
843 | * dirty-state coherency between the page and the buffers. It the page does |
844 | * not have buffers then when they are later attached they will all be set |
845 | * dirty. |
846 | * |
847 | * The buffers are dirtied before the page is dirtied. There's a small race |
848 | * window in which a writepage caller may see the page cleanness but not the |
849 | * buffer dirtiness. That's fine. If this code were to set the page dirty |
850 | * before the buffers, a concurrent writepage caller could clear the page dirty |
851 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean |
852 | * page on the dirty page list. |
853 | * |
854 | * We use private_lock to lock against try_to_free_buffers while using the |
855 | * page's buffer list. Also use this to protect against clean buffers being |
856 | * added to the page after it was set dirty. |
857 | * |
858 | * FIXME: may need to call ->reservepage here as well. That's rather up to the |
859 | * address_space though. |
860 | */ |
861 | int __set_page_dirty_buffers(struct page *page) |
862 | { |
863 | struct address_space * const mapping = page->mapping; |
864 | |
865 | spin_lock(&mapping->private_lock); |
866 | if (page_has_buffers(page)) { |
867 | struct buffer_head *head = page_buffers(page); |
868 | struct buffer_head *bh = head; |
869 | |
870 | do { |
871 | set_buffer_dirty(bh); |
872 | bh = bh->b_this_page; |
873 | } while (bh != head); |
874 | } |
875 | spin_unlock(&mapping->private_lock); |
876 | |
877 | if (!TestSetPageDirty(page)) { |
878 | write_lock_irq(&mapping->tree_lock); |
879 | if (page->mapping) { /* Race with truncate? */ |
880 | if (mapping_cap_account_dirty(mapping)) |
881 | inc_page_state(nr_dirty); |
882 | radix_tree_tag_set(&mapping->page_tree, |
883 | page_index(page), |
884 | PAGECACHE_TAG_DIRTY); |
885 | } |
886 | write_unlock_irq(&mapping->tree_lock); |
887 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
888 | } |
889 | |
890 | return 0; |
891 | } |
892 | EXPORT_SYMBOL(__set_page_dirty_buffers); |
893 | |
894 | /* |
895 | * Write out and wait upon a list of buffers. |
896 | * |
897 | * We have conflicting pressures: we want to make sure that all |
898 | * initially dirty buffers get waited on, but that any subsequently |
899 | * dirtied buffers don't. After all, we don't want fsync to last |
900 | * forever if somebody is actively writing to the file. |
901 | * |
902 | * Do this in two main stages: first we copy dirty buffers to a |
903 | * temporary inode list, queueing the writes as we go. Then we clean |
904 | * up, waiting for those writes to complete. |
905 | * |
906 | * During this second stage, any subsequent updates to the file may end |
907 | * up refiling the buffer on the original inode's dirty list again, so |
908 | * there is a chance we will end up with a buffer queued for write but |
909 | * not yet completed on that list. So, as a final cleanup we go through |
910 | * the osync code to catch these locked, dirty buffers without requeuing |
911 | * any newly dirty buffers for write. |
912 | */ |
913 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) |
914 | { |
915 | struct buffer_head *bh; |
916 | struct list_head tmp; |
917 | int err = 0, err2; |
918 | |
919 | INIT_LIST_HEAD(&tmp); |
920 | |
921 | spin_lock(lock); |
922 | while (!list_empty(list)) { |
923 | bh = BH_ENTRY(list->next); |
924 | list_del_init(&bh->b_assoc_buffers); |
925 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
926 | list_add(&bh->b_assoc_buffers, &tmp); |
927 | if (buffer_dirty(bh)) { |
928 | get_bh(bh); |
929 | spin_unlock(lock); |
930 | /* |
931 | * Ensure any pending I/O completes so that |
932 | * ll_rw_block() actually writes the current |
933 | * contents - it is a noop if I/O is still in |
934 | * flight on potentially older contents. |
935 | */ |
936 | wait_on_buffer(bh); |
937 | ll_rw_block(WRITE, 1, &bh); |
938 | brelse(bh); |
939 | spin_lock(lock); |
940 | } |
941 | } |
942 | } |
943 | |
944 | while (!list_empty(&tmp)) { |
945 | bh = BH_ENTRY(tmp.prev); |
946 | __remove_assoc_queue(bh); |
947 | get_bh(bh); |
948 | spin_unlock(lock); |
949 | wait_on_buffer(bh); |
950 | if (!buffer_uptodate(bh)) |
951 | err = -EIO; |
952 | brelse(bh); |
953 | spin_lock(lock); |
954 | } |
955 | |
956 | spin_unlock(lock); |
957 | err2 = osync_buffers_list(lock, list); |
958 | if (err) |
959 | return err; |
960 | else |
961 | return err2; |
962 | } |
963 | |
964 | /* |
965 | * Invalidate any and all dirty buffers on a given inode. We are |
966 | * probably unmounting the fs, but that doesn't mean we have already |
967 | * done a sync(). Just drop the buffers from the inode list. |
968 | * |
969 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which |
970 | * assumes that all the buffers are against the blockdev. Not true |
971 | * for reiserfs. |
972 | */ |
973 | void invalidate_inode_buffers(struct inode *inode) |
974 | { |
975 | if (inode_has_buffers(inode)) { |
976 | struct address_space *mapping = &inode->i_data; |
977 | struct list_head *list = &mapping->private_list; |
978 | struct address_space *buffer_mapping = mapping->assoc_mapping; |
979 | |
980 | spin_lock(&buffer_mapping->private_lock); |
981 | while (!list_empty(list)) |
982 | __remove_assoc_queue(BH_ENTRY(list->next)); |
983 | spin_unlock(&buffer_mapping->private_lock); |
984 | } |
985 | } |
986 | |
987 | /* |
988 | * Remove any clean buffers from the inode's buffer list. This is called |
989 | * when we're trying to free the inode itself. Those buffers can pin it. |
990 | * |
991 | * Returns true if all buffers were removed. |
992 | */ |
993 | int remove_inode_buffers(struct inode *inode) |
994 | { |
995 | int ret = 1; |
996 | |
997 | if (inode_has_buffers(inode)) { |
998 | struct address_space *mapping = &inode->i_data; |
999 | struct list_head *list = &mapping->private_list; |
1000 | struct address_space *buffer_mapping = mapping->assoc_mapping; |
1001 | |
1002 | spin_lock(&buffer_mapping->private_lock); |
1003 | while (!list_empty(list)) { |
1004 | struct buffer_head *bh = BH_ENTRY(list->next); |
1005 | if (buffer_dirty(bh)) { |
1006 | ret = 0; |
1007 | break; |
1008 | } |
1009 | __remove_assoc_queue(bh); |
1010 | } |
1011 | spin_unlock(&buffer_mapping->private_lock); |
1012 | } |
1013 | return ret; |
1014 | } |
1015 | |
1016 | /* |
1017 | * Create the appropriate buffers when given a page for data area and |
1018 | * the size of each buffer.. Use the bh->b_this_page linked list to |
1019 | * follow the buffers created. Return NULL if unable to create more |
1020 | * buffers. |
1021 | * |
1022 | * The retry flag is used to differentiate async IO (paging, swapping) |
1023 | * which may not fail from ordinary buffer allocations. |
1024 | */ |
1025 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, |
1026 | int retry) |
1027 | { |
1028 | struct buffer_head *bh, *head; |
1029 | long offset; |
1030 | |
1031 | try_again: |
1032 | head = NULL; |
1033 | offset = PAGE_SIZE; |
1034 | while ((offset -= size) >= 0) { |
1035 | bh = alloc_buffer_head(GFP_NOFS); |
1036 | if (!bh) |
1037 | goto no_grow; |
1038 | |
1039 | bh->b_bdev = NULL; |
1040 | bh->b_this_page = head; |
1041 | bh->b_blocknr = -1; |
1042 | head = bh; |
1043 | |
1044 | bh->b_state = 0; |
1045 | atomic_set(&bh->b_count, 0); |
1046 | bh->b_size = size; |
1047 | |
1048 | /* Link the buffer to its page */ |
1049 | set_bh_page(bh, page, offset); |
1050 | |
1051 | bh->b_end_io = NULL; |
1052 | } |
1053 | return head; |
1054 | /* |
1055 | * In case anything failed, we just free everything we got. |
1056 | */ |
1057 | no_grow: |
1058 | if (head) { |
1059 | do { |
1060 | bh = head; |
1061 | head = head->b_this_page; |
1062 | free_buffer_head(bh); |
1063 | } while (head); |
1064 | } |
1065 | |
1066 | /* |
1067 | * Return failure for non-async IO requests. Async IO requests |
1068 | * are not allowed to fail, so we have to wait until buffer heads |
1069 | * become available. But we don't want tasks sleeping with |
1070 | * partially complete buffers, so all were released above. |
1071 | */ |
1072 | if (!retry) |
1073 | return NULL; |
1074 | |
1075 | /* We're _really_ low on memory. Now we just |
1076 | * wait for old buffer heads to become free due to |
1077 | * finishing IO. Since this is an async request and |
1078 | * the reserve list is empty, we're sure there are |
1079 | * async buffer heads in use. |
1080 | */ |
1081 | free_more_memory(); |
1082 | goto try_again; |
1083 | } |
1084 | EXPORT_SYMBOL_GPL(alloc_page_buffers); |
1085 | |
1086 | static inline void |
1087 | link_dev_buffers(struct page *page, struct buffer_head *head) |
1088 | { |
1089 | struct buffer_head *bh, *tail; |
1090 | |
1091 | bh = head; |
1092 | do { |
1093 | tail = bh; |
1094 | bh = bh->b_this_page; |
1095 | } while (bh); |
1096 | tail->b_this_page = head; |
1097 | attach_page_buffers(page, head); |
1098 | } |
1099 | |
1100 | /* |
1101 | * Initialise the state of a blockdev page's buffers. |
1102 | */ |
1103 | static void |
1104 | init_page_buffers(struct page *page, struct block_device *bdev, |
1105 | sector_t block, int size) |
1106 | { |
1107 | struct buffer_head *head = page_buffers(page); |
1108 | struct buffer_head *bh = head; |
1109 | int uptodate = PageUptodate(page); |
1110 | |
1111 | do { |
1112 | if (!buffer_mapped(bh)) { |
1113 | init_buffer(bh, NULL, NULL); |
1114 | bh->b_bdev = bdev; |
1115 | bh->b_blocknr = block; |
1116 | if (uptodate) |
1117 | set_buffer_uptodate(bh); |
1118 | set_buffer_mapped(bh); |
1119 | } |
1120 | block++; |
1121 | bh = bh->b_this_page; |
1122 | } while (bh != head); |
1123 | } |
1124 | |
1125 | /* |
1126 | * Create the page-cache page that contains the requested block. |
1127 | * |
1128 | * This is user purely for blockdev mappings. |
1129 | */ |
1130 | static struct page * |
1131 | grow_dev_page(struct block_device *bdev, sector_t block, |
1132 | pgoff_t index, int size) |
1133 | { |
1134 | struct inode *inode = bdev->bd_inode; |
1135 | struct page *page; |
1136 | struct buffer_head *bh; |
1137 | |
1138 | page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); |
1139 | if (!page) |
1140 | return NULL; |
1141 | |
1142 | if (!PageLocked(page)) |
1143 | BUG(); |
1144 | |
1145 | if (page_has_buffers(page)) { |
1146 | bh = page_buffers(page); |
1147 | if (bh->b_size == size) { |
1148 | init_page_buffers(page, bdev, block, size); |
1149 | return page; |
1150 | } |
1151 | if (!try_to_free_buffers(page)) |
1152 | goto failed; |
1153 | } |
1154 | |
1155 | /* |
1156 | * Allocate some buffers for this page |
1157 | */ |
1158 | bh = alloc_page_buffers(page, size, 0); |
1159 | if (!bh) |
1160 | goto failed; |
1161 | |
1162 | /* |
1163 | * Link the page to the buffers and initialise them. Take the |
1164 | * lock to be atomic wrt __find_get_block(), which does not |
1165 | * run under the page lock. |
1166 | */ |
1167 | spin_lock(&inode->i_mapping->private_lock); |
1168 | link_dev_buffers(page, bh); |
1169 | init_page_buffers(page, bdev, block, size); |
1170 | spin_unlock(&inode->i_mapping->private_lock); |
1171 | return page; |
1172 | |
1173 | failed: |
1174 | BUG(); |
1175 | unlock_page(page); |
1176 | page_cache_release(page); |
1177 | return NULL; |
1178 | } |
1179 | |
1180 | /* |
1181 | * Create buffers for the specified block device block's page. If |
1182 | * that page was dirty, the buffers are set dirty also. |
1183 | * |
1184 | * Except that's a bug. Attaching dirty buffers to a dirty |
1185 | * blockdev's page can result in filesystem corruption, because |
1186 | * some of those buffers may be aliases of filesystem data. |
1187 | * grow_dev_page() will go BUG() if this happens. |
1188 | */ |
1189 | static inline int |
1190 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1191 | { |
1192 | struct page *page; |
1193 | pgoff_t index; |
1194 | int sizebits; |
1195 | |
1196 | sizebits = -1; |
1197 | do { |
1198 | sizebits++; |
1199 | } while ((size << sizebits) < PAGE_SIZE); |
1200 | |
1201 | index = block >> sizebits; |
1202 | block = index << sizebits; |
1203 | |
1204 | /* Create a page with the proper size buffers.. */ |
1205 | page = grow_dev_page(bdev, block, index, size); |
1206 | if (!page) |
1207 | return 0; |
1208 | unlock_page(page); |
1209 | page_cache_release(page); |
1210 | return 1; |
1211 | } |
1212 | |
1213 | static struct buffer_head * |
1214 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1215 | { |
1216 | /* Size must be multiple of hard sectorsize */ |
1217 | if (unlikely(size & (bdev_hardsect_size(bdev)-1) || |
1218 | (size < 512 || size > PAGE_SIZE))) { |
1219 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", |
1220 | size); |
1221 | printk(KERN_ERR "hardsect size: %d\n", |
1222 | bdev_hardsect_size(bdev)); |
1223 | |
1224 | dump_stack(); |
1225 | return NULL; |
1226 | } |
1227 | |
1228 | for (;;) { |
1229 | struct buffer_head * bh; |
1230 | |
1231 | bh = __find_get_block(bdev, block, size); |
1232 | if (bh) |
1233 | return bh; |
1234 | |
1235 | if (!grow_buffers(bdev, block, size)) |
1236 | free_more_memory(); |
1237 | } |
1238 | } |
1239 | |
1240 | /* |
1241 | * The relationship between dirty buffers and dirty pages: |
1242 | * |
1243 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and |
1244 | * the page is tagged dirty in its radix tree. |
1245 | * |
1246 | * At all times, the dirtiness of the buffers represents the dirtiness of |
1247 | * subsections of the page. If the page has buffers, the page dirty bit is |
1248 | * merely a hint about the true dirty state. |
1249 | * |
1250 | * When a page is set dirty in its entirety, all its buffers are marked dirty |
1251 | * (if the page has buffers). |
1252 | * |
1253 | * When a buffer is marked dirty, its page is dirtied, but the page's other |
1254 | * buffers are not. |
1255 | * |
1256 | * Also. When blockdev buffers are explicitly read with bread(), they |
1257 | * individually become uptodate. But their backing page remains not |
1258 | * uptodate - even if all of its buffers are uptodate. A subsequent |
1259 | * block_read_full_page() against that page will discover all the uptodate |
1260 | * buffers, will set the page uptodate and will perform no I/O. |
1261 | */ |
1262 | |
1263 | /** |
1264 | * mark_buffer_dirty - mark a buffer_head as needing writeout |
1265 | * @bh: the buffer_head to mark dirty |
1266 | * |
1267 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its |
1268 | * backing page dirty, then tag the page as dirty in its address_space's radix |
1269 | * tree and then attach the address_space's inode to its superblock's dirty |
1270 | * inode list. |
1271 | * |
1272 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, |
1273 | * mapping->tree_lock and the global inode_lock. |
1274 | */ |
1275 | void fastcall mark_buffer_dirty(struct buffer_head *bh) |
1276 | { |
1277 | if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) |
1278 | __set_page_dirty_nobuffers(bh->b_page); |
1279 | } |
1280 | |
1281 | /* |
1282 | * Decrement a buffer_head's reference count. If all buffers against a page |
1283 | * have zero reference count, are clean and unlocked, and if the page is clean |
1284 | * and unlocked then try_to_free_buffers() may strip the buffers from the page |
1285 | * in preparation for freeing it (sometimes, rarely, buffers are removed from |
1286 | * a page but it ends up not being freed, and buffers may later be reattached). |
1287 | */ |
1288 | void __brelse(struct buffer_head * buf) |
1289 | { |
1290 | if (atomic_read(&buf->b_count)) { |
1291 | put_bh(buf); |
1292 | return; |
1293 | } |
1294 | printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
1295 | WARN_ON(1); |
1296 | } |
1297 | |
1298 | /* |
1299 | * bforget() is like brelse(), except it discards any |
1300 | * potentially dirty data. |
1301 | */ |
1302 | void __bforget(struct buffer_head *bh) |
1303 | { |
1304 | clear_buffer_dirty(bh); |
1305 | if (!list_empty(&bh->b_assoc_buffers)) { |
1306 | struct address_space *buffer_mapping = bh->b_page->mapping; |
1307 | |
1308 | spin_lock(&buffer_mapping->private_lock); |
1309 | list_del_init(&bh->b_assoc_buffers); |
1310 | spin_unlock(&buffer_mapping->private_lock); |
1311 | } |
1312 | __brelse(bh); |
1313 | } |
1314 | |
1315 | static struct buffer_head *__bread_slow(struct buffer_head *bh) |
1316 | { |
1317 | lock_buffer(bh); |
1318 | if (buffer_uptodate(bh)) { |
1319 | unlock_buffer(bh); |
1320 | return bh; |
1321 | } else { |
1322 | get_bh(bh); |
1323 | bh->b_end_io = end_buffer_read_sync; |
1324 | submit_bh(READ, bh); |
1325 | wait_on_buffer(bh); |
1326 | if (buffer_uptodate(bh)) |
1327 | return bh; |
1328 | } |
1329 | brelse(bh); |
1330 | return NULL; |
1331 | } |
1332 | |
1333 | /* |
1334 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). |
1335 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their |
1336 | * refcount elevated by one when they're in an LRU. A buffer can only appear |
1337 | * once in a particular CPU's LRU. A single buffer can be present in multiple |
1338 | * CPU's LRUs at the same time. |
1339 | * |
1340 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and |
1341 | * sb_find_get_block(). |
1342 | * |
1343 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use |
1344 | * a local interrupt disable for that. |
1345 | */ |
1346 | |
1347 | #define BH_LRU_SIZE 8 |
1348 | |
1349 | struct bh_lru { |
1350 | struct buffer_head *bhs[BH_LRU_SIZE]; |
1351 | }; |
1352 | |
1353 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; |
1354 | |
1355 | #ifdef CONFIG_SMP |
1356 | #define bh_lru_lock() local_irq_disable() |
1357 | #define bh_lru_unlock() local_irq_enable() |
1358 | #else |
1359 | #define bh_lru_lock() preempt_disable() |
1360 | #define bh_lru_unlock() preempt_enable() |
1361 | #endif |
1362 | |
1363 | static inline void check_irqs_on(void) |
1364 | { |
1365 | #ifdef irqs_disabled |
1366 | BUG_ON(irqs_disabled()); |
1367 | #endif |
1368 | } |
1369 | |
1370 | /* |
1371 | * The LRU management algorithm is dopey-but-simple. Sorry. |
1372 | */ |
1373 | static void bh_lru_install(struct buffer_head *bh) |
1374 | { |
1375 | struct buffer_head *evictee = NULL; |
1376 | struct bh_lru *lru; |
1377 | |
1378 | check_irqs_on(); |
1379 | bh_lru_lock(); |
1380 | lru = &__get_cpu_var(bh_lrus); |
1381 | if (lru->bhs[0] != bh) { |
1382 | struct buffer_head *bhs[BH_LRU_SIZE]; |
1383 | int in; |
1384 | int out = 0; |
1385 | |
1386 | get_bh(bh); |
1387 | bhs[out++] = bh; |
1388 | for (in = 0; in < BH_LRU_SIZE; in++) { |
1389 | struct buffer_head *bh2 = lru->bhs[in]; |
1390 | |
1391 | if (bh2 == bh) { |
1392 | __brelse(bh2); |
1393 | } else { |
1394 | if (out >= BH_LRU_SIZE) { |
1395 | BUG_ON(evictee != NULL); |
1396 | evictee = bh2; |
1397 | } else { |
1398 | bhs[out++] = bh2; |
1399 | } |
1400 | } |
1401 | } |
1402 | while (out < BH_LRU_SIZE) |
1403 | bhs[out++] = NULL; |
1404 | memcpy(lru->bhs, bhs, sizeof(bhs)); |
1405 | } |
1406 | bh_lru_unlock(); |
1407 | |
1408 | if (evictee) |
1409 | __brelse(evictee); |
1410 | } |
1411 | |
1412 | /* |
1413 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. |
1414 | */ |
1415 | static inline struct buffer_head * |
1416 | lookup_bh_lru(struct block_device *bdev, sector_t block, int size) |
1417 | { |
1418 | struct buffer_head *ret = NULL; |
1419 | struct bh_lru *lru; |
1420 | int i; |
1421 | |
1422 | check_irqs_on(); |
1423 | bh_lru_lock(); |
1424 | lru = &__get_cpu_var(bh_lrus); |
1425 | for (i = 0; i < BH_LRU_SIZE; i++) { |
1426 | struct buffer_head *bh = lru->bhs[i]; |
1427 | |
1428 | if (bh && bh->b_bdev == bdev && |
1429 | bh->b_blocknr == block && bh->b_size == size) { |
1430 | if (i) { |
1431 | while (i) { |
1432 | lru->bhs[i] = lru->bhs[i - 1]; |
1433 | i--; |
1434 | } |
1435 | lru->bhs[0] = bh; |
1436 | } |
1437 | get_bh(bh); |
1438 | ret = bh; |
1439 | break; |
1440 | } |
1441 | } |
1442 | bh_lru_unlock(); |
1443 | return ret; |
1444 | } |
1445 | |
1446 | /* |
1447 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh |
1448 | * it in the LRU and mark it as accessed. If it is not present then return |
1449 | * NULL |
1450 | */ |
1451 | struct buffer_head * |
1452 | __find_get_block(struct block_device *bdev, sector_t block, int size) |
1453 | { |
1454 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); |
1455 | |
1456 | if (bh == NULL) { |
1457 | bh = __find_get_block_slow(bdev, block, size); |
1458 | if (bh) |
1459 | bh_lru_install(bh); |
1460 | } |
1461 | if (bh) |
1462 | touch_buffer(bh); |
1463 | return bh; |
1464 | } |
1465 | EXPORT_SYMBOL(__find_get_block); |
1466 | |
1467 | /* |
1468 | * __getblk will locate (and, if necessary, create) the buffer_head |
1469 | * which corresponds to the passed block_device, block and size. The |
1470 | * returned buffer has its reference count incremented. |
1471 | * |
1472 | * __getblk() cannot fail - it just keeps trying. If you pass it an |
1473 | * illegal block number, __getblk() will happily return a buffer_head |
1474 | * which represents the non-existent block. Very weird. |
1475 | * |
1476 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() |
1477 | * attempt is failing. FIXME, perhaps? |
1478 | */ |
1479 | struct buffer_head * |
1480 | __getblk(struct block_device *bdev, sector_t block, int size) |
1481 | { |
1482 | struct buffer_head *bh = __find_get_block(bdev, block, size); |
1483 | |
1484 | might_sleep(); |
1485 | if (bh == NULL) |
1486 | bh = __getblk_slow(bdev, block, size); |
1487 | return bh; |
1488 | } |
1489 | EXPORT_SYMBOL(__getblk); |
1490 | |
1491 | /* |
1492 | * Do async read-ahead on a buffer.. |
1493 | */ |
1494 | void __breadahead(struct block_device *bdev, sector_t block, int size) |
1495 | { |
1496 | struct buffer_head *bh = __getblk(bdev, block, size); |
1497 | ll_rw_block(READA, 1, &bh); |
1498 | brelse(bh); |
1499 | } |
1500 | EXPORT_SYMBOL(__breadahead); |
1501 | |
1502 | /** |
1503 | * __bread() - reads a specified block and returns the bh |
1504 | * @bdev: the block_device to read from |
1505 | * @block: number of block |
1506 | * @size: size (in bytes) to read |
1507 | * |
1508 | * Reads a specified block, and returns buffer head that contains it. |
1509 | * It returns NULL if the block was unreadable. |
1510 | */ |
1511 | struct buffer_head * |
1512 | __bread(struct block_device *bdev, sector_t block, int size) |
1513 | { |
1514 | struct buffer_head *bh = __getblk(bdev, block, size); |
1515 | |
1516 | if (!buffer_uptodate(bh)) |
1517 | bh = __bread_slow(bh); |
1518 | return bh; |
1519 | } |
1520 | EXPORT_SYMBOL(__bread); |
1521 | |
1522 | /* |
1523 | * invalidate_bh_lrus() is called rarely - but not only at unmount. |
1524 | * This doesn't race because it runs in each cpu either in irq |
1525 | * or with preempt disabled. |
1526 | */ |
1527 | static void invalidate_bh_lru(void *arg) |
1528 | { |
1529 | struct bh_lru *b = &get_cpu_var(bh_lrus); |
1530 | int i; |
1531 | |
1532 | for (i = 0; i < BH_LRU_SIZE; i++) { |
1533 | brelse(b->bhs[i]); |
1534 | b->bhs[i] = NULL; |
1535 | } |
1536 | put_cpu_var(bh_lrus); |
1537 | } |
1538 | |
1539 | static void invalidate_bh_lrus(void) |
1540 | { |
1541 | on_each_cpu(invalidate_bh_lru, NULL, 1, 1); |
1542 | } |
1543 | |
1544 | void set_bh_page(struct buffer_head *bh, |
1545 | struct page *page, unsigned long offset) |
1546 | { |
1547 | bh->b_page = page; |
1548 | if (offset >= PAGE_SIZE) |
1549 | BUG(); |
1550 | if (PageHighMem(page)) |
1551 | /* |
1552 | * This catches illegal uses and preserves the offset: |
1553 | */ |
1554 | bh->b_data = (char *)(0 + offset); |
1555 | else |
1556 | bh->b_data = page_address(page) + offset; |
1557 | } |
1558 | EXPORT_SYMBOL(set_bh_page); |
1559 | |
1560 | /* |
1561 | * Called when truncating a buffer on a page completely. |
1562 | */ |
1563 | static inline void discard_buffer(struct buffer_head * bh) |
1564 | { |
1565 | lock_buffer(bh); |
1566 | clear_buffer_dirty(bh); |
1567 | bh->b_bdev = NULL; |
1568 | clear_buffer_mapped(bh); |
1569 | clear_buffer_req(bh); |
1570 | clear_buffer_new(bh); |
1571 | clear_buffer_delay(bh); |
1572 | unlock_buffer(bh); |
1573 | } |
1574 | |
1575 | /** |
1576 | * try_to_release_page() - release old fs-specific metadata on a page |
1577 | * |
1578 | * @page: the page which the kernel is trying to free |
1579 | * @gfp_mask: memory allocation flags (and I/O mode) |
1580 | * |
1581 | * The address_space is to try to release any data against the page |
1582 | * (presumably at page->private). If the release was successful, return `1'. |
1583 | * Otherwise return zero. |
1584 | * |
1585 | * The @gfp_mask argument specifies whether I/O may be performed to release |
1586 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). |
1587 | * |
1588 | * NOTE: @gfp_mask may go away, and this function may become non-blocking. |
1589 | */ |
1590 | int try_to_release_page(struct page *page, int gfp_mask) |
1591 | { |
1592 | struct address_space * const mapping = page->mapping; |
1593 | |
1594 | BUG_ON(!PageLocked(page)); |
1595 | if (PageWriteback(page)) |
1596 | return 0; |
1597 | |
1598 | if (mapping && mapping->a_ops->releasepage) |
1599 | return mapping->a_ops->releasepage(page, gfp_mask); |
1600 | return try_to_free_buffers(page); |
1601 | } |
1602 | EXPORT_SYMBOL(try_to_release_page); |
1603 | |
1604 | /** |
1605 | * block_invalidatepage - invalidate part of all of a buffer-backed page |
1606 | * |
1607 | * @page: the page which is affected |
1608 | * @offset: the index of the truncation point |
1609 | * |
1610 | * block_invalidatepage() is called when all or part of the page has become |
1611 | * invalidatedby a truncate operation. |
1612 | * |
1613 | * block_invalidatepage() does not have to release all buffers, but it must |
1614 | * ensure that no dirty buffer is left outside @offset and that no I/O |
1615 | * is underway against any of the blocks which are outside the truncation |
1616 | * point. Because the caller is about to free (and possibly reuse) those |
1617 | * blocks on-disk. |
1618 | */ |
1619 | int block_invalidatepage(struct page *page, unsigned long offset) |
1620 | { |
1621 | struct buffer_head *head, *bh, *next; |
1622 | unsigned int curr_off = 0; |
1623 | int ret = 1; |
1624 | |
1625 | BUG_ON(!PageLocked(page)); |
1626 | if (!page_has_buffers(page)) |
1627 | goto out; |
1628 | |
1629 | head = page_buffers(page); |
1630 | bh = head; |
1631 | do { |
1632 | unsigned int next_off = curr_off + bh->b_size; |
1633 | next = bh->b_this_page; |
1634 | |
1635 | /* |
1636 | * is this block fully invalidated? |
1637 | */ |
1638 | if (offset <= curr_off) |
1639 | discard_buffer(bh); |
1640 | curr_off = next_off; |
1641 | bh = next; |
1642 | } while (bh != head); |
1643 | |
1644 | /* |
1645 | * We release buffers only if the entire page is being invalidated. |
1646 | * The get_block cached value has been unconditionally invalidated, |
1647 | * so real IO is not possible anymore. |
1648 | */ |
1649 | if (offset == 0) |
1650 | ret = try_to_release_page(page, 0); |
1651 | out: |
1652 | return ret; |
1653 | } |
1654 | EXPORT_SYMBOL(block_invalidatepage); |
1655 | |
1656 | /* |
1657 | * We attach and possibly dirty the buffers atomically wrt |
1658 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers |
1659 | * is already excluded via the page lock. |
1660 | */ |
1661 | void create_empty_buffers(struct page *page, |
1662 | unsigned long blocksize, unsigned long b_state) |
1663 | { |
1664 | struct buffer_head *bh, *head, *tail; |
1665 | |
1666 | head = alloc_page_buffers(page, blocksize, 1); |
1667 | bh = head; |
1668 | do { |
1669 | bh->b_state |= b_state; |
1670 | tail = bh; |
1671 | bh = bh->b_this_page; |
1672 | } while (bh); |
1673 | tail->b_this_page = head; |
1674 | |
1675 | spin_lock(&page->mapping->private_lock); |
1676 | if (PageUptodate(page) || PageDirty(page)) { |
1677 | bh = head; |
1678 | do { |
1679 | if (PageDirty(page)) |
1680 | set_buffer_dirty(bh); |
1681 | if (PageUptodate(page)) |
1682 | set_buffer_uptodate(bh); |
1683 | bh = bh->b_this_page; |
1684 | } while (bh != head); |
1685 | } |
1686 | attach_page_buffers(page, head); |
1687 | spin_unlock(&page->mapping->private_lock); |
1688 | } |
1689 | EXPORT_SYMBOL(create_empty_buffers); |
1690 | |
1691 | /* |
1692 | * We are taking a block for data and we don't want any output from any |
1693 | * buffer-cache aliases starting from return from that function and |
1694 | * until the moment when something will explicitly mark the buffer |
1695 | * dirty (hopefully that will not happen until we will free that block ;-) |
1696 | * We don't even need to mark it not-uptodate - nobody can expect |
1697 | * anything from a newly allocated buffer anyway. We used to used |
1698 | * unmap_buffer() for such invalidation, but that was wrong. We definitely |
1699 | * don't want to mark the alias unmapped, for example - it would confuse |
1700 | * anyone who might pick it with bread() afterwards... |
1701 | * |
1702 | * Also.. Note that bforget() doesn't lock the buffer. So there can |
1703 | * be writeout I/O going on against recently-freed buffers. We don't |
1704 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O |
1705 | * only if we really need to. That happens here. |
1706 | */ |
1707 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) |
1708 | { |
1709 | struct buffer_head *old_bh; |
1710 | |
1711 | might_sleep(); |
1712 | |
1713 | old_bh = __find_get_block_slow(bdev, block, 0); |
1714 | if (old_bh) { |
1715 | clear_buffer_dirty(old_bh); |
1716 | wait_on_buffer(old_bh); |
1717 | clear_buffer_req(old_bh); |
1718 | __brelse(old_bh); |
1719 | } |
1720 | } |
1721 | EXPORT_SYMBOL(unmap_underlying_metadata); |
1722 | |
1723 | /* |
1724 | * NOTE! All mapped/uptodate combinations are valid: |
1725 | * |
1726 | * Mapped Uptodate Meaning |
1727 | * |
1728 | * No No "unknown" - must do get_block() |
1729 | * No Yes "hole" - zero-filled |
1730 | * Yes No "allocated" - allocated on disk, not read in |
1731 | * Yes Yes "valid" - allocated and up-to-date in memory. |
1732 | * |
1733 | * "Dirty" is valid only with the last case (mapped+uptodate). |
1734 | */ |
1735 | |
1736 | /* |
1737 | * While block_write_full_page is writing back the dirty buffers under |
1738 | * the page lock, whoever dirtied the buffers may decide to clean them |
1739 | * again at any time. We handle that by only looking at the buffer |
1740 | * state inside lock_buffer(). |
1741 | * |
1742 | * If block_write_full_page() is called for regular writeback |
1743 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a |
1744 | * locked buffer. This only can happen if someone has written the buffer |
1745 | * directly, with submit_bh(). At the address_space level PageWriteback |
1746 | * prevents this contention from occurring. |
1747 | */ |
1748 | static int __block_write_full_page(struct inode *inode, struct page *page, |
1749 | get_block_t *get_block, struct writeback_control *wbc) |
1750 | { |
1751 | int err; |
1752 | sector_t block; |
1753 | sector_t last_block; |
1754 | struct buffer_head *bh, *head; |
1755 | int nr_underway = 0; |
1756 | |
1757 | BUG_ON(!PageLocked(page)); |
1758 | |
1759 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; |
1760 | |
1761 | if (!page_has_buffers(page)) { |
1762 | create_empty_buffers(page, 1 << inode->i_blkbits, |
1763 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1764 | } |
1765 | |
1766 | /* |
1767 | * Be very careful. We have no exclusion from __set_page_dirty_buffers |
1768 | * here, and the (potentially unmapped) buffers may become dirty at |
1769 | * any time. If a buffer becomes dirty here after we've inspected it |
1770 | * then we just miss that fact, and the page stays dirty. |
1771 | * |
1772 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; |
1773 | * handle that here by just cleaning them. |
1774 | */ |
1775 | |
1776 | block = page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1777 | head = page_buffers(page); |
1778 | bh = head; |
1779 | |
1780 | /* |
1781 | * Get all the dirty buffers mapped to disk addresses and |
1782 | * handle any aliases from the underlying blockdev's mapping. |
1783 | */ |
1784 | do { |
1785 | if (block > last_block) { |
1786 | /* |
1787 | * mapped buffers outside i_size will occur, because |
1788 | * this page can be outside i_size when there is a |
1789 | * truncate in progress. |
1790 | */ |
1791 | /* |
1792 | * The buffer was zeroed by block_write_full_page() |
1793 | */ |
1794 | clear_buffer_dirty(bh); |
1795 | set_buffer_uptodate(bh); |
1796 | } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { |
1797 | err = get_block(inode, block, bh, 1); |
1798 | if (err) |
1799 | goto recover; |
1800 | if (buffer_new(bh)) { |
1801 | /* blockdev mappings never come here */ |
1802 | clear_buffer_new(bh); |
1803 | unmap_underlying_metadata(bh->b_bdev, |
1804 | bh->b_blocknr); |
1805 | } |
1806 | } |
1807 | bh = bh->b_this_page; |
1808 | block++; |
1809 | } while (bh != head); |
1810 | |
1811 | do { |
1812 | if (!buffer_mapped(bh)) |
1813 | continue; |
1814 | /* |
1815 | * If it's a fully non-blocking write attempt and we cannot |
1816 | * lock the buffer then redirty the page. Note that this can |
1817 | * potentially cause a busy-wait loop from pdflush and kswapd |
1818 | * activity, but those code paths have their own higher-level |
1819 | * throttling. |
1820 | */ |
1821 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { |
1822 | lock_buffer(bh); |
1823 | } else if (test_set_buffer_locked(bh)) { |
1824 | redirty_page_for_writepage(wbc, page); |
1825 | continue; |
1826 | } |
1827 | if (test_clear_buffer_dirty(bh)) { |
1828 | mark_buffer_async_write(bh); |
1829 | } else { |
1830 | unlock_buffer(bh); |
1831 | } |
1832 | } while ((bh = bh->b_this_page) != head); |
1833 | |
1834 | /* |
1835 | * The page and its buffers are protected by PageWriteback(), so we can |
1836 | * drop the bh refcounts early. |
1837 | */ |
1838 | BUG_ON(PageWriteback(page)); |
1839 | set_page_writeback(page); |
1840 | |
1841 | do { |
1842 | struct buffer_head *next = bh->b_this_page; |
1843 | if (buffer_async_write(bh)) { |
1844 | submit_bh(WRITE, bh); |
1845 | nr_underway++; |
1846 | } |
1847 | bh = next; |
1848 | } while (bh != head); |
1849 | unlock_page(page); |
1850 | |
1851 | err = 0; |
1852 | done: |
1853 | if (nr_underway == 0) { |
1854 | /* |
1855 | * The page was marked dirty, but the buffers were |
1856 | * clean. Someone wrote them back by hand with |
1857 | * ll_rw_block/submit_bh. A rare case. |
1858 | */ |
1859 | int uptodate = 1; |
1860 | do { |
1861 | if (!buffer_uptodate(bh)) { |
1862 | uptodate = 0; |
1863 | break; |
1864 | } |
1865 | bh = bh->b_this_page; |
1866 | } while (bh != head); |
1867 | if (uptodate) |
1868 | SetPageUptodate(page); |
1869 | end_page_writeback(page); |
1870 | /* |
1871 | * The page and buffer_heads can be released at any time from |
1872 | * here on. |
1873 | */ |
1874 | wbc->pages_skipped++; /* We didn't write this page */ |
1875 | } |
1876 | return err; |
1877 | |
1878 | recover: |
1879 | /* |
1880 | * ENOSPC, or some other error. We may already have added some |
1881 | * blocks to the file, so we need to write these out to avoid |
1882 | * exposing stale data. |
1883 | * The page is currently locked and not marked for writeback |
1884 | */ |
1885 | bh = head; |
1886 | /* Recovery: lock and submit the mapped buffers */ |
1887 | do { |
1888 | if (buffer_mapped(bh) && buffer_dirty(bh)) { |
1889 | lock_buffer(bh); |
1890 | mark_buffer_async_write(bh); |
1891 | } else { |
1892 | /* |
1893 | * The buffer may have been set dirty during |
1894 | * attachment to a dirty page. |
1895 | */ |
1896 | clear_buffer_dirty(bh); |
1897 | } |
1898 | } while ((bh = bh->b_this_page) != head); |
1899 | SetPageError(page); |
1900 | BUG_ON(PageWriteback(page)); |
1901 | set_page_writeback(page); |
1902 | unlock_page(page); |
1903 | do { |
1904 | struct buffer_head *next = bh->b_this_page; |
1905 | if (buffer_async_write(bh)) { |
1906 | clear_buffer_dirty(bh); |
1907 | submit_bh(WRITE, bh); |
1908 | nr_underway++; |
1909 | } |
1910 | bh = next; |
1911 | } while (bh != head); |
1912 | goto done; |
1913 | } |
1914 | |
1915 | static int __block_prepare_write(struct inode *inode, struct page *page, |
1916 | unsigned from, unsigned to, get_block_t *get_block) |
1917 | { |
1918 | unsigned block_start, block_end; |
1919 | sector_t block; |
1920 | int err = 0; |
1921 | unsigned blocksize, bbits; |
1922 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; |
1923 | |
1924 | BUG_ON(!PageLocked(page)); |
1925 | BUG_ON(from > PAGE_CACHE_SIZE); |
1926 | BUG_ON(to > PAGE_CACHE_SIZE); |
1927 | BUG_ON(from > to); |
1928 | |
1929 | blocksize = 1 << inode->i_blkbits; |
1930 | if (!page_has_buffers(page)) |
1931 | create_empty_buffers(page, blocksize, 0); |
1932 | head = page_buffers(page); |
1933 | |
1934 | bbits = inode->i_blkbits; |
1935 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); |
1936 | |
1937 | for(bh = head, block_start = 0; bh != head || !block_start; |
1938 | block++, block_start=block_end, bh = bh->b_this_page) { |
1939 | block_end = block_start + blocksize; |
1940 | if (block_end <= from || block_start >= to) { |
1941 | if (PageUptodate(page)) { |
1942 | if (!buffer_uptodate(bh)) |
1943 | set_buffer_uptodate(bh); |
1944 | } |
1945 | continue; |
1946 | } |
1947 | if (buffer_new(bh)) |
1948 | clear_buffer_new(bh); |
1949 | if (!buffer_mapped(bh)) { |
1950 | err = get_block(inode, block, bh, 1); |
1951 | if (err) |
1952 | break; |
1953 | if (buffer_new(bh)) { |
1954 | clear_buffer_new(bh); |
1955 | unmap_underlying_metadata(bh->b_bdev, |
1956 | bh->b_blocknr); |
1957 | if (PageUptodate(page)) { |
1958 | set_buffer_uptodate(bh); |
1959 | continue; |
1960 | } |
1961 | if (block_end > to || block_start < from) { |
1962 | void *kaddr; |
1963 | |
1964 | kaddr = kmap_atomic(page, KM_USER0); |
1965 | if (block_end > to) |
1966 | memset(kaddr+to, 0, |
1967 | block_end-to); |
1968 | if (block_start < from) |
1969 | memset(kaddr+block_start, |
1970 | 0, from-block_start); |
1971 | flush_dcache_page(page); |
1972 | kunmap_atomic(kaddr, KM_USER0); |
1973 | } |
1974 | continue; |
1975 | } |
1976 | } |
1977 | if (PageUptodate(page)) { |
1978 | if (!buffer_uptodate(bh)) |
1979 | set_buffer_uptodate(bh); |
1980 | continue; |
1981 | } |
1982 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && |
1983 | (block_start < from || block_end > to)) { |
1984 | ll_rw_block(READ, 1, &bh); |
1985 | *wait_bh++=bh; |
1986 | } |
1987 | } |
1988 | /* |
1989 | * If we issued read requests - let them complete. |
1990 | */ |
1991 | while(wait_bh > wait) { |
1992 | wait_on_buffer(*--wait_bh); |
1993 | if (!buffer_uptodate(*wait_bh)) |
1994 | err = -EIO; |
1995 | } |
1996 | if (!err) |
1997 | return err; |
1998 | |
1999 | /* Error case: */ |
2000 | /* |
2001 | * Zero out any newly allocated blocks to avoid exposing stale |
2002 | * data. If BH_New is set, we know that the block was newly |
2003 | * allocated in the above loop. |
2004 | */ |
2005 | bh = head; |
2006 | block_start = 0; |
2007 | do { |
2008 | block_end = block_start+blocksize; |
2009 | if (block_end <= from) |
2010 | goto next_bh; |
2011 | if (block_start >= to) |
2012 | break; |
2013 | if (buffer_new(bh)) { |
2014 | void *kaddr; |
2015 | |
2016 | clear_buffer_new(bh); |
2017 | kaddr = kmap_atomic(page, KM_USER0); |
2018 | memset(kaddr+block_start, 0, bh->b_size); |
2019 | kunmap_atomic(kaddr, KM_USER0); |
2020 | set_buffer_uptodate(bh); |
2021 | mark_buffer_dirty(bh); |
2022 | } |
2023 | next_bh: |
2024 | block_start = block_end; |
2025 | bh = bh->b_this_page; |
2026 | } while (bh != head); |
2027 | return err; |
2028 | } |
2029 | |
2030 | static int __block_commit_write(struct inode *inode, struct page *page, |
2031 | unsigned from, unsigned to) |
2032 | { |
2033 | unsigned block_start, block_end; |
2034 | int partial = 0; |
2035 | unsigned blocksize; |
2036 | struct buffer_head *bh, *head; |
2037 | |
2038 | blocksize = 1 << inode->i_blkbits; |
2039 | |
2040 | for(bh = head = page_buffers(page), block_start = 0; |
2041 | bh != head || !block_start; |
2042 | block_start=block_end, bh = bh->b_this_page) { |
2043 | block_end = block_start + blocksize; |
2044 | if (block_end <= from || block_start >= to) { |
2045 | if (!buffer_uptodate(bh)) |
2046 | partial = 1; |
2047 | } else { |
2048 | set_buffer_uptodate(bh); |
2049 | mark_buffer_dirty(bh); |
2050 | } |
2051 | } |
2052 | |
2053 | /* |
2054 | * If this is a partial write which happened to make all buffers |
2055 | * uptodate then we can optimize away a bogus readpage() for |
2056 | * the next read(). Here we 'discover' whether the page went |
2057 | * uptodate as a result of this (potentially partial) write. |
2058 | */ |
2059 | if (!partial) |
2060 | SetPageUptodate(page); |
2061 | return 0; |
2062 | } |
2063 | |
2064 | /* |
2065 | * Generic "read page" function for block devices that have the normal |
2066 | * get_block functionality. This is most of the block device filesystems. |
2067 | * Reads the page asynchronously --- the unlock_buffer() and |
2068 | * set/clear_buffer_uptodate() functions propagate buffer state into the |
2069 | * page struct once IO has completed. |
2070 | */ |
2071 | int block_read_full_page(struct page *page, get_block_t *get_block) |
2072 | { |
2073 | struct inode *inode = page->mapping->host; |
2074 | sector_t iblock, lblock; |
2075 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; |
2076 | unsigned int blocksize; |
2077 | int nr, i; |
2078 | int fully_mapped = 1; |
2079 | |
2080 | BUG_ON(!PageLocked(page)); |
2081 | blocksize = 1 << inode->i_blkbits; |
2082 | if (!page_has_buffers(page)) |
2083 | create_empty_buffers(page, blocksize, 0); |
2084 | head = page_buffers(page); |
2085 | |
2086 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
2087 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; |
2088 | bh = head; |
2089 | nr = 0; |
2090 | i = 0; |
2091 | |
2092 | do { |
2093 | if (buffer_uptodate(bh)) |
2094 | continue; |
2095 | |
2096 | if (!buffer_mapped(bh)) { |
2097 | int err = 0; |
2098 | |
2099 | fully_mapped = 0; |
2100 | if (iblock < lblock) { |
2101 | err = get_block(inode, iblock, bh, 0); |
2102 | if (err) |
2103 | SetPageError(page); |
2104 | } |
2105 | if (!buffer_mapped(bh)) { |
2106 | void *kaddr = kmap_atomic(page, KM_USER0); |
2107 | memset(kaddr + i * blocksize, 0, blocksize); |
2108 | flush_dcache_page(page); |
2109 | kunmap_atomic(kaddr, KM_USER0); |
2110 | if (!err) |
2111 | set_buffer_uptodate(bh); |
2112 | continue; |
2113 | } |
2114 | /* |
2115 | * get_block() might have updated the buffer |
2116 | * synchronously |
2117 | */ |
2118 | if (buffer_uptodate(bh)) |
2119 | continue; |
2120 | } |
2121 | arr[nr++] = bh; |
2122 | } while (i++, iblock++, (bh = bh->b_this_page) != head); |
2123 | |
2124 | if (fully_mapped) |
2125 | SetPageMappedToDisk(page); |
2126 | |
2127 | if (!nr) { |
2128 | /* |
2129 | * All buffers are uptodate - we can set the page uptodate |
2130 | * as well. But not if get_block() returned an error. |
2131 | */ |
2132 | if (!PageError(page)) |
2133 | SetPageUptodate(page); |
2134 | unlock_page(page); |
2135 | return 0; |
2136 | } |
2137 | |
2138 | /* Stage two: lock the buffers */ |
2139 | for (i = 0; i < nr; i++) { |
2140 | bh = arr[i]; |
2141 | lock_buffer(bh); |
2142 | mark_buffer_async_read(bh); |
2143 | } |
2144 | |
2145 | /* |
2146 | * Stage 3: start the IO. Check for uptodateness |
2147 | * inside the buffer lock in case another process reading |
2148 | * the underlying blockdev brought it uptodate (the sct fix). |
2149 | */ |
2150 | for (i = 0; i < nr; i++) { |
2151 | bh = arr[i]; |
2152 | if (buffer_uptodate(bh)) |
2153 | end_buffer_async_read(bh, 1); |
2154 | else |
2155 | submit_bh(READ, bh); |
2156 | } |
2157 | return 0; |
2158 | } |
2159 | |
2160 | /* utility function for filesystems that need to do work on expanding |
2161 | * truncates. Uses prepare/commit_write to allow the filesystem to |
2162 | * deal with the hole. |
2163 | */ |
2164 | int generic_cont_expand(struct inode *inode, loff_t size) |
2165 | { |
2166 | struct address_space *mapping = inode->i_mapping; |
2167 | struct page *page; |
2168 | unsigned long index, offset, limit; |
2169 | int err; |
2170 | |
2171 | err = -EFBIG; |
2172 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; |
2173 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { |
2174 | send_sig(SIGXFSZ, current, 0); |
2175 | goto out; |
2176 | } |
2177 | if (size > inode->i_sb->s_maxbytes) |
2178 | goto out; |
2179 | |
2180 | offset = (size & (PAGE_CACHE_SIZE-1)); /* Within page */ |
2181 | |
2182 | /* ugh. in prepare/commit_write, if from==to==start of block, we |
2183 | ** skip the prepare. make sure we never send an offset for the start |
2184 | ** of a block |
2185 | */ |
2186 | if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { |
2187 | offset++; |
2188 | } |
2189 | index = size >> PAGE_CACHE_SHIFT; |
2190 | err = -ENOMEM; |
2191 | page = grab_cache_page(mapping, index); |
2192 | if (!page) |
2193 | goto out; |
2194 | err = mapping->a_ops->prepare_write(NULL, page, offset, offset); |
2195 | if (!err) { |
2196 | err = mapping->a_ops->commit_write(NULL, page, offset, offset); |
2197 | } |
2198 | unlock_page(page); |
2199 | page_cache_release(page); |
2200 | if (err > 0) |
2201 | err = 0; |
2202 | out: |
2203 | return err; |
2204 | } |
2205 | |
2206 | /* |
2207 | * For moronic filesystems that do not allow holes in file. |
2208 | * We may have to extend the file. |
2209 | */ |
2210 | |
2211 | int cont_prepare_write(struct page *page, unsigned offset, |
2212 | unsigned to, get_block_t *get_block, loff_t *bytes) |
2213 | { |
2214 | struct address_space *mapping = page->mapping; |
2215 | struct inode *inode = mapping->host; |
2216 | struct page *new_page; |
2217 | pgoff_t pgpos; |
2218 | long status; |
2219 | unsigned zerofrom; |
2220 | unsigned blocksize = 1 << inode->i_blkbits; |
2221 | void *kaddr; |
2222 | |
2223 | while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { |
2224 | status = -ENOMEM; |
2225 | new_page = grab_cache_page(mapping, pgpos); |
2226 | if (!new_page) |
2227 | goto out; |
2228 | /* we might sleep */ |
2229 | if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { |
2230 | unlock_page(new_page); |
2231 | page_cache_release(new_page); |
2232 | continue; |
2233 | } |
2234 | zerofrom = *bytes & ~PAGE_CACHE_MASK; |
2235 | if (zerofrom & (blocksize-1)) { |
2236 | *bytes |= (blocksize-1); |
2237 | (*bytes)++; |
2238 | } |
2239 | status = __block_prepare_write(inode, new_page, zerofrom, |
2240 | PAGE_CACHE_SIZE, get_block); |
2241 | if (status) |
2242 | goto out_unmap; |
2243 | kaddr = kmap_atomic(new_page, KM_USER0); |
2244 | memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); |
2245 | flush_dcache_page(new_page); |
2246 | kunmap_atomic(kaddr, KM_USER0); |
2247 | generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); |
2248 | unlock_page(new_page); |
2249 | page_cache_release(new_page); |
2250 | } |
2251 | |
2252 | if (page->index < pgpos) { |
2253 | /* completely inside the area */ |
2254 | zerofrom = offset; |
2255 | } else { |
2256 | /* page covers the boundary, find the boundary offset */ |
2257 | zerofrom = *bytes & ~PAGE_CACHE_MASK; |
2258 | |
2259 | /* if we will expand the thing last block will be filled */ |
2260 | if (to > zerofrom && (zerofrom & (blocksize-1))) { |
2261 | *bytes |= (blocksize-1); |
2262 | (*bytes)++; |
2263 | } |
2264 | |
2265 | /* starting below the boundary? Nothing to zero out */ |
2266 | if (offset <= zerofrom) |
2267 | zerofrom = offset; |
2268 | } |
2269 | status = __block_prepare_write(inode, page, zerofrom, to, get_block); |
2270 | if (status) |
2271 | goto out1; |
2272 | if (zerofrom < offset) { |
2273 | kaddr = kmap_atomic(page, KM_USER0); |
2274 | memset(kaddr+zerofrom, 0, offset-zerofrom); |
2275 | flush_dcache_page(page); |
2276 | kunmap_atomic(kaddr, KM_USER0); |
2277 | __block_commit_write(inode, page, zerofrom, offset); |
2278 | } |
2279 | return 0; |
2280 | out1: |
2281 | ClearPageUptodate(page); |
2282 | return status; |
2283 | |
2284 | out_unmap: |
2285 | ClearPageUptodate(new_page); |
2286 | unlock_page(new_page); |
2287 | page_cache_release(new_page); |
2288 | out: |
2289 | return status; |
2290 | } |
2291 | |
2292 | int block_prepare_write(struct page *page, unsigned from, unsigned to, |
2293 | get_block_t *get_block) |
2294 | { |
2295 | struct inode *inode = page->mapping->host; |
2296 | int err = __block_prepare_write(inode, page, from, to, get_block); |
2297 | if (err) |
2298 | ClearPageUptodate(page); |
2299 | return err; |
2300 | } |
2301 | |
2302 | int block_commit_write(struct page *page, unsigned from, unsigned to) |
2303 | { |
2304 | struct inode *inode = page->mapping->host; |
2305 | __block_commit_write(inode,page,from,to); |
2306 | return 0; |
2307 | } |
2308 | |
2309 | int generic_commit_write(struct file *file, struct page *page, |
2310 | unsigned from, unsigned to) |
2311 | { |
2312 | struct inode *inode = page->mapping->host; |
2313 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; |
2314 | __block_commit_write(inode,page,from,to); |
2315 | /* |
2316 | * No need to use i_size_read() here, the i_size |
2317 | * cannot change under us because we hold i_sem. |
2318 | */ |
2319 | if (pos > inode->i_size) { |
2320 | i_size_write(inode, pos); |
2321 | mark_inode_dirty(inode); |
2322 | } |
2323 | return 0; |
2324 | } |
2325 | |
2326 | |
2327 | /* |
2328 | * nobh_prepare_write()'s prereads are special: the buffer_heads are freed |
2329 | * immediately, while under the page lock. So it needs a special end_io |
2330 | * handler which does not touch the bh after unlocking it. |
2331 | * |
2332 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but |
2333 | * a race there is benign: unlock_buffer() only use the bh's address for |
2334 | * hashing after unlocking the buffer, so it doesn't actually touch the bh |
2335 | * itself. |
2336 | */ |
2337 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) |
2338 | { |
2339 | if (uptodate) { |
2340 | set_buffer_uptodate(bh); |
2341 | } else { |
2342 | /* This happens, due to failed READA attempts. */ |
2343 | clear_buffer_uptodate(bh); |
2344 | } |
2345 | unlock_buffer(bh); |
2346 | } |
2347 | |
2348 | /* |
2349 | * On entry, the page is fully not uptodate. |
2350 | * On exit the page is fully uptodate in the areas outside (from,to) |
2351 | */ |
2352 | int nobh_prepare_write(struct page *page, unsigned from, unsigned to, |
2353 | get_block_t *get_block) |
2354 | { |
2355 | struct inode *inode = page->mapping->host; |
2356 | const unsigned blkbits = inode->i_blkbits; |
2357 | const unsigned blocksize = 1 << blkbits; |
2358 | struct buffer_head map_bh; |
2359 | struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; |
2360 | unsigned block_in_page; |
2361 | unsigned block_start; |
2362 | sector_t block_in_file; |
2363 | char *kaddr; |
2364 | int nr_reads = 0; |
2365 | int i; |
2366 | int ret = 0; |
2367 | int is_mapped_to_disk = 1; |
2368 | int dirtied_it = 0; |
2369 | |
2370 | if (PageMappedToDisk(page)) |
2371 | return 0; |
2372 | |
2373 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
2374 | map_bh.b_page = page; |
2375 | |
2376 | /* |
2377 | * We loop across all blocks in the page, whether or not they are |
2378 | * part of the affected region. This is so we can discover if the |
2379 | * page is fully mapped-to-disk. |
2380 | */ |
2381 | for (block_start = 0, block_in_page = 0; |
2382 | block_start < PAGE_CACHE_SIZE; |
2383 | block_in_page++, block_start += blocksize) { |
2384 | unsigned block_end = block_start + blocksize; |
2385 | int create; |
2386 | |
2387 | map_bh.b_state = 0; |
2388 | create = 1; |
2389 | if (block_start >= to) |
2390 | create = 0; |
2391 | ret = get_block(inode, block_in_file + block_in_page, |
2392 | &map_bh, create); |
2393 | if (ret) |
2394 | goto failed; |
2395 | if (!buffer_mapped(&map_bh)) |
2396 | is_mapped_to_disk = 0; |
2397 | if (buffer_new(&map_bh)) |
2398 | unmap_underlying_metadata(map_bh.b_bdev, |
2399 | map_bh.b_blocknr); |
2400 | if (PageUptodate(page)) |
2401 | continue; |
2402 | if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { |
2403 | kaddr = kmap_atomic(page, KM_USER0); |
2404 | if (block_start < from) { |
2405 | memset(kaddr+block_start, 0, from-block_start); |
2406 | dirtied_it = 1; |
2407 | } |
2408 | if (block_end > to) { |
2409 | memset(kaddr + to, 0, block_end - to); |
2410 | dirtied_it = 1; |
2411 | } |
2412 | flush_dcache_page(page); |
2413 | kunmap_atomic(kaddr, KM_USER0); |
2414 | continue; |
2415 | } |
2416 | if (buffer_uptodate(&map_bh)) |
2417 | continue; /* reiserfs does this */ |
2418 | if (block_start < from || block_end > to) { |
2419 | struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); |
2420 | |
2421 | if (!bh) { |
2422 | ret = -ENOMEM; |
2423 | goto failed; |
2424 | } |
2425 | bh->b_state = map_bh.b_state; |
2426 | atomic_set(&bh->b_count, 0); |
2427 | bh->b_this_page = NULL; |
2428 | bh->b_page = page; |
2429 | bh->b_blocknr = map_bh.b_blocknr; |
2430 | bh->b_size = blocksize; |
2431 | bh->b_data = (char *)(long)block_start; |
2432 | bh->b_bdev = map_bh.b_bdev; |
2433 | bh->b_private = NULL; |
2434 | read_bh[nr_reads++] = bh; |
2435 | } |
2436 | } |
2437 | |
2438 | if (nr_reads) { |
2439 | struct buffer_head *bh; |
2440 | |
2441 | /* |
2442 | * The page is locked, so these buffers are protected from |
2443 | * any VM or truncate activity. Hence we don't need to care |
2444 | * for the buffer_head refcounts. |
2445 | */ |
2446 | for (i = 0; i < nr_reads; i++) { |
2447 | bh = read_bh[i]; |
2448 | lock_buffer(bh); |
2449 | bh->b_end_io = end_buffer_read_nobh; |
2450 | submit_bh(READ, bh); |
2451 | } |
2452 | for (i = 0; i < nr_reads; i++) { |
2453 | bh = read_bh[i]; |
2454 | wait_on_buffer(bh); |
2455 | if (!buffer_uptodate(bh)) |
2456 | ret = -EIO; |
2457 | free_buffer_head(bh); |
2458 | read_bh[i] = NULL; |
2459 | } |
2460 | if (ret) |
2461 | goto failed; |
2462 | } |
2463 | |
2464 | if (is_mapped_to_disk) |
2465 | SetPageMappedToDisk(page); |
2466 | SetPageUptodate(page); |
2467 | |
2468 | /* |
2469 | * Setting the page dirty here isn't necessary for the prepare_write |
2470 | * function - commit_write will do that. But if/when this function is |
2471 | * used within the pagefault handler to ensure that all mmapped pages |
2472 | * have backing space in the filesystem, we will need to dirty the page |
2473 | * if its contents were altered. |
2474 | */ |
2475 | if (dirtied_it) |
2476 | set_page_dirty(page); |
2477 | |
2478 | return 0; |
2479 | |
2480 | failed: |
2481 | for (i = 0; i < nr_reads; i++) { |
2482 | if (read_bh[i]) |
2483 | free_buffer_head(read_bh[i]); |
2484 | } |
2485 | |
2486 | /* |
2487 | * Error recovery is pretty slack. Clear the page and mark it dirty |
2488 | * so we'll later zero out any blocks which _were_ allocated. |
2489 | */ |
2490 | kaddr = kmap_atomic(page, KM_USER0); |
2491 | memset(kaddr, 0, PAGE_CACHE_SIZE); |
2492 | kunmap_atomic(kaddr, KM_USER0); |
2493 | SetPageUptodate(page); |
2494 | set_page_dirty(page); |
2495 | return ret; |
2496 | } |
2497 | EXPORT_SYMBOL(nobh_prepare_write); |
2498 | |
2499 | int nobh_commit_write(struct file *file, struct page *page, |
2500 | unsigned from, unsigned to) |
2501 | { |
2502 | struct inode *inode = page->mapping->host; |
2503 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; |
2504 | |
2505 | set_page_dirty(page); |
2506 | if (pos > inode->i_size) { |
2507 | i_size_write(inode, pos); |
2508 | mark_inode_dirty(inode); |
2509 | } |
2510 | return 0; |
2511 | } |
2512 | EXPORT_SYMBOL(nobh_commit_write); |
2513 | |
2514 | /* |
2515 | * nobh_writepage() - based on block_full_write_page() except |
2516 | * that it tries to operate without attaching bufferheads to |
2517 | * the page. |
2518 | */ |
2519 | int nobh_writepage(struct page *page, get_block_t *get_block, |
2520 | struct writeback_control *wbc) |
2521 | { |
2522 | struct inode * const inode = page->mapping->host; |
2523 | loff_t i_size = i_size_read(inode); |
2524 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; |
2525 | unsigned offset; |
2526 | void *kaddr; |
2527 | int ret; |
2528 | |
2529 | /* Is the page fully inside i_size? */ |
2530 | if (page->index < end_index) |
2531 | goto out; |
2532 | |
2533 | /* Is the page fully outside i_size? (truncate in progress) */ |
2534 | offset = i_size & (PAGE_CACHE_SIZE-1); |
2535 | if (page->index >= end_index+1 || !offset) { |
2536 | /* |
2537 | * The page may have dirty, unmapped buffers. For example, |
2538 | * they may have been added in ext3_writepage(). Make them |
2539 | * freeable here, so the page does not leak. |
2540 | */ |
2541 | #if 0 |
2542 | /* Not really sure about this - do we need this ? */ |
2543 | if (page->mapping->a_ops->invalidatepage) |
2544 | page->mapping->a_ops->invalidatepage(page, offset); |
2545 | #endif |
2546 | unlock_page(page); |
2547 | return 0; /* don't care */ |
2548 | } |
2549 | |
2550 | /* |
2551 | * The page straddles i_size. It must be zeroed out on each and every |
2552 | * writepage invocation because it may be mmapped. "A file is mapped |
2553 | * in multiples of the page size. For a file that is not a multiple of |
2554 | * the page size, the remaining memory is zeroed when mapped, and |
2555 | * writes to that region are not written out to the file." |
2556 | */ |
2557 | kaddr = kmap_atomic(page, KM_USER0); |
2558 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); |
2559 | flush_dcache_page(page); |
2560 | kunmap_atomic(kaddr, KM_USER0); |
2561 | out: |
2562 | ret = mpage_writepage(page, get_block, wbc); |
2563 | if (ret == -EAGAIN) |
2564 | ret = __block_write_full_page(inode, page, get_block, wbc); |
2565 | return ret; |
2566 | } |
2567 | EXPORT_SYMBOL(nobh_writepage); |
2568 | |
2569 | /* |
2570 | * This function assumes that ->prepare_write() uses nobh_prepare_write(). |
2571 | */ |
2572 | int nobh_truncate_page(struct address_space *mapping, loff_t from) |
2573 | { |
2574 | struct inode *inode = mapping->host; |
2575 | unsigned blocksize = 1 << inode->i_blkbits; |
2576 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2577 | unsigned offset = from & (PAGE_CACHE_SIZE-1); |
2578 | unsigned to; |
2579 | struct page *page; |
2580 | struct address_space_operations *a_ops = mapping->a_ops; |
2581 | char *kaddr; |
2582 | int ret = 0; |
2583 | |
2584 | if ((offset & (blocksize - 1)) == 0) |
2585 | goto out; |
2586 | |
2587 | ret = -ENOMEM; |
2588 | page = grab_cache_page(mapping, index); |
2589 | if (!page) |
2590 | goto out; |
2591 | |
2592 | to = (offset + blocksize) & ~(blocksize - 1); |
2593 | ret = a_ops->prepare_write(NULL, page, offset, to); |
2594 | if (ret == 0) { |
2595 | kaddr = kmap_atomic(page, KM_USER0); |
2596 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); |
2597 | flush_dcache_page(page); |
2598 | kunmap_atomic(kaddr, KM_USER0); |
2599 | set_page_dirty(page); |
2600 | } |
2601 | unlock_page(page); |
2602 | page_cache_release(page); |
2603 | out: |
2604 | return ret; |
2605 | } |
2606 | EXPORT_SYMBOL(nobh_truncate_page); |
2607 | |
2608 | int block_truncate_page(struct address_space *mapping, |
2609 | loff_t from, get_block_t *get_block) |
2610 | { |
2611 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2612 | unsigned offset = from & (PAGE_CACHE_SIZE-1); |
2613 | unsigned blocksize; |
2614 | pgoff_t iblock; |
2615 | unsigned length, pos; |
2616 | struct inode *inode = mapping->host; |
2617 | struct page *page; |
2618 | struct buffer_head *bh; |
2619 | void *kaddr; |
2620 | int err; |
2621 | |
2622 | blocksize = 1 << inode->i_blkbits; |
2623 | length = offset & (blocksize - 1); |
2624 | |
2625 | /* Block boundary? Nothing to do */ |
2626 | if (!length) |
2627 | return 0; |
2628 | |
2629 | length = blocksize - length; |
2630 | iblock = index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
2631 | |
2632 | page = grab_cache_page(mapping, index); |
2633 | err = -ENOMEM; |
2634 | if (!page) |
2635 | goto out; |
2636 | |
2637 | if (!page_has_buffers(page)) |
2638 | create_empty_buffers(page, blocksize, 0); |
2639 | |
2640 | /* Find the buffer that contains "offset" */ |
2641 | bh = page_buffers(page); |
2642 | pos = blocksize; |
2643 | while (offset >= pos) { |
2644 | bh = bh->b_this_page; |
2645 | iblock++; |
2646 | pos += blocksize; |
2647 | } |
2648 | |
2649 | err = 0; |
2650 | if (!buffer_mapped(bh)) { |
2651 | err = get_block(inode, iblock, bh, 0); |
2652 | if (err) |
2653 | goto unlock; |
2654 | /* unmapped? It's a hole - nothing to do */ |
2655 | if (!buffer_mapped(bh)) |
2656 | goto unlock; |
2657 | } |
2658 | |
2659 | /* Ok, it's mapped. Make sure it's up-to-date */ |
2660 | if (PageUptodate(page)) |
2661 | set_buffer_uptodate(bh); |
2662 | |
2663 | if (!buffer_uptodate(bh) && !buffer_delay(bh)) { |
2664 | err = -EIO; |
2665 | ll_rw_block(READ, 1, &bh); |
2666 | wait_on_buffer(bh); |
2667 | /* Uhhuh. Read error. Complain and punt. */ |
2668 | if (!buffer_uptodate(bh)) |
2669 | goto unlock; |
2670 | } |
2671 | |
2672 | kaddr = kmap_atomic(page, KM_USER0); |
2673 | memset(kaddr + offset, 0, length); |
2674 | flush_dcache_page(page); |
2675 | kunmap_atomic(kaddr, KM_USER0); |
2676 | |
2677 | mark_buffer_dirty(bh); |
2678 | err = 0; |
2679 | |
2680 | unlock: |
2681 | unlock_page(page); |
2682 | page_cache_release(page); |
2683 | out: |
2684 | return err; |
2685 | } |
2686 | |
2687 | /* |
2688 | * The generic ->writepage function for buffer-backed address_spaces |
2689 | */ |
2690 | int block_write_full_page(struct page *page, get_block_t *get_block, |
2691 | struct writeback_control *wbc) |
2692 | { |
2693 | struct inode * const inode = page->mapping->host; |
2694 | loff_t i_size = i_size_read(inode); |
2695 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; |
2696 | unsigned offset; |
2697 | void *kaddr; |
2698 | |
2699 | /* Is the page fully inside i_size? */ |
2700 | if (page->index < end_index) |
2701 | return __block_write_full_page(inode, page, get_block, wbc); |
2702 | |
2703 | /* Is the page fully outside i_size? (truncate in progress) */ |
2704 | offset = i_size & (PAGE_CACHE_SIZE-1); |
2705 | if (page->index >= end_index+1 || !offset) { |
2706 | /* |
2707 | * The page may have dirty, unmapped buffers. For example, |
2708 | * they may have been added in ext3_writepage(). Make them |
2709 | * freeable here, so the page does not leak. |
2710 | */ |
2711 | block_invalidatepage(page, 0); |
2712 | unlock_page(page); |
2713 | return 0; /* don't care */ |
2714 | } |
2715 | |
2716 | /* |
2717 | * The page straddles i_size. It must be zeroed out on each and every |
2718 | * writepage invokation because it may be mmapped. "A file is mapped |
2719 | * in multiples of the page size. For a file that is not a multiple of |
2720 | * the page size, the remaining memory is zeroed when mapped, and |
2721 | * writes to that region are not written out to the file." |
2722 | */ |
2723 | kaddr = kmap_atomic(page, KM_USER0); |
2724 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); |
2725 | flush_dcache_page(page); |
2726 | kunmap_atomic(kaddr, KM_USER0); |
2727 | return __block_write_full_page(inode, page, get_block, wbc); |
2728 | } |
2729 | |
2730 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, |
2731 | get_block_t *get_block) |
2732 | { |
2733 | struct buffer_head tmp; |
2734 | struct inode *inode = mapping->host; |
2735 | tmp.b_state = 0; |
2736 | tmp.b_blocknr = 0; |
2737 | get_block(inode, block, &tmp, 0); |
2738 | return tmp.b_blocknr; |
2739 | } |
2740 | |
2741 | static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) |
2742 | { |
2743 | struct buffer_head *bh = bio->bi_private; |
2744 | |
2745 | if (bio->bi_size) |
2746 | return 1; |
2747 | |
2748 | if (err == -EOPNOTSUPP) { |
2749 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); |
2750 | set_bit(BH_Eopnotsupp, &bh->b_state); |
2751 | } |
2752 | |
2753 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); |
2754 | bio_put(bio); |
2755 | return 0; |
2756 | } |
2757 | |
2758 | int submit_bh(int rw, struct buffer_head * bh) |
2759 | { |
2760 | struct bio *bio; |
2761 | int ret = 0; |
2762 | |
2763 | BUG_ON(!buffer_locked(bh)); |
2764 | BUG_ON(!buffer_mapped(bh)); |
2765 | BUG_ON(!bh->b_end_io); |
2766 | |
2767 | if (buffer_ordered(bh) && (rw == WRITE)) |
2768 | rw = WRITE_BARRIER; |
2769 | |
2770 | /* |
2771 | * Only clear out a write error when rewriting, should this |
2772 | * include WRITE_SYNC as well? |
2773 | */ |
2774 | if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) |
2775 | clear_buffer_write_io_error(bh); |
2776 | |
2777 | /* |
2778 | * from here on down, it's all bio -- do the initial mapping, |
2779 | * submit_bio -> generic_make_request may further map this bio around |
2780 | */ |
2781 | bio = bio_alloc(GFP_NOIO, 1); |
2782 | |
2783 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); |
2784 | bio->bi_bdev = bh->b_bdev; |
2785 | bio->bi_io_vec[0].bv_page = bh->b_page; |
2786 | bio->bi_io_vec[0].bv_len = bh->b_size; |
2787 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); |
2788 | |
2789 | bio->bi_vcnt = 1; |
2790 | bio->bi_idx = 0; |
2791 | bio->bi_size = bh->b_size; |
2792 | |
2793 | bio->bi_end_io = end_bio_bh_io_sync; |
2794 | bio->bi_private = bh; |
2795 | |
2796 | bio_get(bio); |
2797 | submit_bio(rw, bio); |
2798 | |
2799 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) |
2800 | ret = -EOPNOTSUPP; |
2801 | |
2802 | bio_put(bio); |
2803 | return ret; |
2804 | } |
2805 | |
2806 | /** |
2807 | * ll_rw_block: low-level access to block devices (DEPRECATED) |
2808 | * @rw: whether to %READ or %WRITE or maybe %READA (readahead) |
2809 | * @nr: number of &struct buffer_heads in the array |
2810 | * @bhs: array of pointers to &struct buffer_head |
2811 | * |
2812 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, |
2813 | * and requests an I/O operation on them, either a %READ or a %WRITE. |
2814 | * The third %READA option is described in the documentation for |
2815 | * generic_make_request() which ll_rw_block() calls. |
2816 | * |
2817 | * This function drops any buffer that it cannot get a lock on (with the |
2818 | * BH_Lock state bit), any buffer that appears to be clean when doing a |
2819 | * write request, and any buffer that appears to be up-to-date when doing |
2820 | * read request. Further it marks as clean buffers that are processed for |
2821 | * writing (the buffer cache won't assume that they are actually clean until |
2822 | * the buffer gets unlocked). |
2823 | * |
2824 | * ll_rw_block sets b_end_io to simple completion handler that marks |
2825 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes |
2826 | * any waiters. |
2827 | * |
2828 | * All of the buffers must be for the same device, and must also be a |
2829 | * multiple of the current approved size for the device. |
2830 | */ |
2831 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) |
2832 | { |
2833 | int i; |
2834 | |
2835 | for (i = 0; i < nr; i++) { |
2836 | struct buffer_head *bh = bhs[i]; |
2837 | |
2838 | if (test_set_buffer_locked(bh)) |
2839 | continue; |
2840 | |
2841 | get_bh(bh); |
2842 | if (rw == WRITE) { |
2843 | if (test_clear_buffer_dirty(bh)) { |
2844 | bh->b_end_io = end_buffer_write_sync; |
2845 | submit_bh(WRITE, bh); |
2846 | continue; |
2847 | } |
2848 | } else { |
2849 | if (!buffer_uptodate(bh)) { |
2850 | bh->b_end_io = end_buffer_read_sync; |
2851 | submit_bh(rw, bh); |
2852 | continue; |
2853 | } |
2854 | } |
2855 | unlock_buffer(bh); |
2856 | put_bh(bh); |
2857 | } |
2858 | } |
2859 | |
2860 | /* |
2861 | * For a data-integrity writeout, we need to wait upon any in-progress I/O |
2862 | * and then start new I/O and then wait upon it. The caller must have a ref on |
2863 | * the buffer_head. |
2864 | */ |
2865 | int sync_dirty_buffer(struct buffer_head *bh) |
2866 | { |
2867 | int ret = 0; |
2868 | |
2869 | WARN_ON(atomic_read(&bh->b_count) < 1); |
2870 | lock_buffer(bh); |
2871 | if (test_clear_buffer_dirty(bh)) { |
2872 | get_bh(bh); |
2873 | bh->b_end_io = end_buffer_write_sync; |
2874 | ret = submit_bh(WRITE, bh); |
2875 | wait_on_buffer(bh); |
2876 | if (buffer_eopnotsupp(bh)) { |
2877 | clear_buffer_eopnotsupp(bh); |
2878 | ret = -EOPNOTSUPP; |
2879 | } |
2880 | if (!ret && !buffer_uptodate(bh)) |
2881 | ret = -EIO; |
2882 | } else { |
2883 | unlock_buffer(bh); |
2884 | } |
2885 | return ret; |
2886 | } |
2887 | |
2888 | /* |
2889 | * try_to_free_buffers() checks if all the buffers on this particular page |
2890 | * are unused, and releases them if so. |
2891 | * |
2892 | * Exclusion against try_to_free_buffers may be obtained by either |
2893 | * locking the page or by holding its mapping's private_lock. |
2894 | * |
2895 | * If the page is dirty but all the buffers are clean then we need to |
2896 | * be sure to mark the page clean as well. This is because the page |
2897 | * may be against a block device, and a later reattachment of buffers |
2898 | * to a dirty page will set *all* buffers dirty. Which would corrupt |
2899 | * filesystem data on the same device. |
2900 | * |
2901 | * The same applies to regular filesystem pages: if all the buffers are |
2902 | * clean then we set the page clean and proceed. To do that, we require |
2903 | * total exclusion from __set_page_dirty_buffers(). That is obtained with |
2904 | * private_lock. |
2905 | * |
2906 | * try_to_free_buffers() is non-blocking. |
2907 | */ |
2908 | static inline int buffer_busy(struct buffer_head *bh) |
2909 | { |
2910 | return atomic_read(&bh->b_count) | |
2911 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); |
2912 | } |
2913 | |
2914 | static int |
2915 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) |
2916 | { |
2917 | struct buffer_head *head = page_buffers(page); |
2918 | struct buffer_head *bh; |
2919 | |
2920 | bh = head; |
2921 | do { |
2922 | if (buffer_write_io_error(bh) && page->mapping) |
2923 | set_bit(AS_EIO, &page->mapping->flags); |
2924 | if (buffer_busy(bh)) |
2925 | goto failed; |
2926 | bh = bh->b_this_page; |
2927 | } while (bh != head); |
2928 | |
2929 | do { |
2930 | struct buffer_head *next = bh->b_this_page; |
2931 | |
2932 | if (!list_empty(&bh->b_assoc_buffers)) |
2933 | __remove_assoc_queue(bh); |
2934 | bh = next; |
2935 | } while (bh != head); |
2936 | *buffers_to_free = head; |
2937 | __clear_page_buffers(page); |
2938 | return 1; |
2939 | failed: |
2940 | return 0; |
2941 | } |
2942 | |
2943 | int try_to_free_buffers(struct page *page) |
2944 | { |
2945 | struct address_space * const mapping = page->mapping; |
2946 | struct buffer_head *buffers_to_free = NULL; |
2947 | int ret = 0; |
2948 | |
2949 | BUG_ON(!PageLocked(page)); |
2950 | if (PageWriteback(page)) |
2951 | return 0; |
2952 | |
2953 | if (mapping == NULL) { /* can this still happen? */ |
2954 | ret = drop_buffers(page, &buffers_to_free); |
2955 | goto out; |
2956 | } |
2957 | |
2958 | spin_lock(&mapping->private_lock); |
2959 | ret = drop_buffers(page, &buffers_to_free); |
2960 | if (ret) { |
2961 | /* |
2962 | * If the filesystem writes its buffers by hand (eg ext3) |
2963 | * then we can have clean buffers against a dirty page. We |
2964 | * clean the page here; otherwise later reattachment of buffers |
2965 | * could encounter a non-uptodate page, which is unresolvable. |
2966 | * This only applies in the rare case where try_to_free_buffers |
2967 | * succeeds but the page is not freed. |
2968 | */ |
2969 | clear_page_dirty(page); |
2970 | } |
2971 | spin_unlock(&mapping->private_lock); |
2972 | out: |
2973 | if (buffers_to_free) { |
2974 | struct buffer_head *bh = buffers_to_free; |
2975 | |
2976 | do { |
2977 | struct buffer_head *next = bh->b_this_page; |
2978 | free_buffer_head(bh); |
2979 | bh = next; |
2980 | } while (bh != buffers_to_free); |
2981 | } |
2982 | return ret; |
2983 | } |
2984 | EXPORT_SYMBOL(try_to_free_buffers); |
2985 | |
2986 | int block_sync_page(struct page *page) |
2987 | { |
2988 | struct address_space *mapping; |
2989 | |
2990 | smp_mb(); |
2991 | mapping = page_mapping(page); |
2992 | if (mapping) |
2993 | blk_run_backing_dev(mapping->backing_dev_info, page); |
2994 | return 0; |
2995 | } |
2996 | |
2997 | /* |
2998 | * There are no bdflush tunables left. But distributions are |
2999 | * still running obsolete flush daemons, so we terminate them here. |
3000 | * |
3001 | * Use of bdflush() is deprecated and will be removed in a future kernel. |
3002 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. |
3003 | */ |
3004 | asmlinkage long sys_bdflush(int func, long data) |
3005 | { |
3006 | static int msg_count; |
3007 | |
3008 | if (!capable(CAP_SYS_ADMIN)) |
3009 | return -EPERM; |
3010 | |
3011 | if (msg_count < 5) { |
3012 | msg_count++; |
3013 | printk(KERN_INFO |
3014 | "warning: process `%s' used the obsolete bdflush" |
3015 | " system call\n", current->comm); |
3016 | printk(KERN_INFO "Fix your initscripts?\n"); |
3017 | } |
3018 | |
3019 | if (func == 1) |
3020 | do_exit(0); |
3021 | return 0; |
3022 | } |
3023 | |
3024 | /* |
3025 | * Buffer-head allocation |
3026 | */ |
3027 | static kmem_cache_t *bh_cachep; |
3028 | |
3029 | /* |
3030 | * Once the number of bh's in the machine exceeds this level, we start |
3031 | * stripping them in writeback. |
3032 | */ |
3033 | static int max_buffer_heads; |
3034 | |
3035 | int buffer_heads_over_limit; |
3036 | |
3037 | struct bh_accounting { |
3038 | int nr; /* Number of live bh's */ |
3039 | int ratelimit; /* Limit cacheline bouncing */ |
3040 | }; |
3041 | |
3042 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; |
3043 | |
3044 | static void recalc_bh_state(void) |
3045 | { |
3046 | int i; |
3047 | int tot = 0; |
3048 | |
3049 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) |
3050 | return; |
3051 | __get_cpu_var(bh_accounting).ratelimit = 0; |
3052 | for_each_cpu(i) |
3053 | tot += per_cpu(bh_accounting, i).nr; |
3054 | buffer_heads_over_limit = (tot > max_buffer_heads); |
3055 | } |
3056 | |
3057 | struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags) |
3058 | { |
3059 | struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); |
3060 | if (ret) { |
3061 | preempt_disable(); |
3062 | __get_cpu_var(bh_accounting).nr++; |
3063 | recalc_bh_state(); |
3064 | preempt_enable(); |
3065 | } |
3066 | return ret; |
3067 | } |
3068 | EXPORT_SYMBOL(alloc_buffer_head); |
3069 | |
3070 | void free_buffer_head(struct buffer_head *bh) |
3071 | { |
3072 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); |
3073 | kmem_cache_free(bh_cachep, bh); |
3074 | preempt_disable(); |
3075 | __get_cpu_var(bh_accounting).nr--; |
3076 | recalc_bh_state(); |
3077 | preempt_enable(); |
3078 | } |
3079 | EXPORT_SYMBOL(free_buffer_head); |
3080 | |
3081 | static void |
3082 | init_buffer_head(void *data, kmem_cache_t *cachep, unsigned long flags) |
3083 | { |
3084 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == |
3085 | SLAB_CTOR_CONSTRUCTOR) { |
3086 | struct buffer_head * bh = (struct buffer_head *)data; |
3087 | |
3088 | memset(bh, 0, sizeof(*bh)); |
3089 | INIT_LIST_HEAD(&bh->b_assoc_buffers); |
3090 | } |
3091 | } |
3092 | |
3093 | #ifdef CONFIG_HOTPLUG_CPU |
3094 | static void buffer_exit_cpu(int cpu) |
3095 | { |
3096 | int i; |
3097 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); |
3098 | |
3099 | for (i = 0; i < BH_LRU_SIZE; i++) { |
3100 | brelse(b->bhs[i]); |
3101 | b->bhs[i] = NULL; |
3102 | } |
3103 | } |
3104 | |
3105 | static int buffer_cpu_notify(struct notifier_block *self, |
3106 | unsigned long action, void *hcpu) |
3107 | { |
3108 | if (action == CPU_DEAD) |
3109 | buffer_exit_cpu((unsigned long)hcpu); |
3110 | return NOTIFY_OK; |
3111 | } |
3112 | #endif /* CONFIG_HOTPLUG_CPU */ |
3113 | |
3114 | void __init buffer_init(void) |
3115 | { |
3116 | int nrpages; |
3117 | |
3118 | bh_cachep = kmem_cache_create("buffer_head", |
3119 | sizeof(struct buffer_head), 0, |
3120 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC, init_buffer_head, NULL); |
3121 | |
3122 | /* |
3123 | * Limit the bh occupancy to 10% of ZONE_NORMAL |
3124 | */ |
3125 | nrpages = (nr_free_buffer_pages() * 10) / 100; |
3126 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); |
3127 | hotcpu_notifier(buffer_cpu_notify, 0); |
3128 | } |
3129 | |
3130 | EXPORT_SYMBOL(__bforget); |
3131 | EXPORT_SYMBOL(__brelse); |
3132 | EXPORT_SYMBOL(__wait_on_buffer); |
3133 | EXPORT_SYMBOL(block_commit_write); |
3134 | EXPORT_SYMBOL(block_prepare_write); |
3135 | EXPORT_SYMBOL(block_read_full_page); |
3136 | EXPORT_SYMBOL(block_sync_page); |
3137 | EXPORT_SYMBOL(block_truncate_page); |
3138 | EXPORT_SYMBOL(block_write_full_page); |
3139 | EXPORT_SYMBOL(cont_prepare_write); |
3140 | EXPORT_SYMBOL(end_buffer_async_write); |
3141 | EXPORT_SYMBOL(end_buffer_read_sync); |
3142 | EXPORT_SYMBOL(end_buffer_write_sync); |
3143 | EXPORT_SYMBOL(file_fsync); |
3144 | EXPORT_SYMBOL(fsync_bdev); |
3145 | EXPORT_SYMBOL(generic_block_bmap); |
3146 | EXPORT_SYMBOL(generic_commit_write); |
3147 | EXPORT_SYMBOL(generic_cont_expand); |
3148 | EXPORT_SYMBOL(init_buffer); |
3149 | EXPORT_SYMBOL(invalidate_bdev); |
3150 | EXPORT_SYMBOL(ll_rw_block); |
3151 | EXPORT_SYMBOL(mark_buffer_dirty); |
3152 | EXPORT_SYMBOL(submit_bh); |
3153 | EXPORT_SYMBOL(sync_dirty_buffer); |
3154 | EXPORT_SYMBOL(unlock_buffer); |