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1da177e4 LT |
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; | |
d59dd462 | 221 | smp_wmb(); |
1da177e4 LT |
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; | |
d59dd462 | 238 | smp_wmb(); |
1da177e4 LT |
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; | |
d59dd462 | 266 | smp_wmb(); |
1da177e4 LT |
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 | |
67be2dd1 | 777 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
778 | * |
779 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
780 | * that I/O. | |
781 | * | |
67be2dd1 MW |
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(). | |
1da177e4 LT |
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 | 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 | |
67be2dd1 | 1265 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
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 | |
67be2dd1 | 1504 | * @bdev: the block_device to read from |
1da177e4 LT |
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 | get_bh(bh); | |
1813 | if (!buffer_mapped(bh)) | |
1814 | continue; | |
1815 | /* | |
1816 | * If it's a fully non-blocking write attempt and we cannot | |
1817 | * lock the buffer then redirty the page. Note that this can | |
1818 | * potentially cause a busy-wait loop from pdflush and kswapd | |
1819 | * activity, but those code paths have their own higher-level | |
1820 | * throttling. | |
1821 | */ | |
1822 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { | |
1823 | lock_buffer(bh); | |
1824 | } else if (test_set_buffer_locked(bh)) { | |
1825 | redirty_page_for_writepage(wbc, page); | |
1826 | continue; | |
1827 | } | |
1828 | if (test_clear_buffer_dirty(bh)) { | |
1829 | mark_buffer_async_write(bh); | |
1830 | } else { | |
1831 | unlock_buffer(bh); | |
1832 | } | |
1833 | } while ((bh = bh->b_this_page) != head); | |
1834 | ||
1835 | /* | |
1836 | * The page and its buffers are protected by PageWriteback(), so we can | |
1837 | * drop the bh refcounts early. | |
1838 | */ | |
1839 | BUG_ON(PageWriteback(page)); | |
1840 | set_page_writeback(page); | |
1841 | unlock_page(page); | |
1842 | ||
1843 | do { | |
1844 | struct buffer_head *next = bh->b_this_page; | |
1845 | if (buffer_async_write(bh)) { | |
1846 | submit_bh(WRITE, bh); | |
1847 | nr_underway++; | |
1848 | } | |
1849 | put_bh(bh); | |
1850 | bh = next; | |
1851 | } while (bh != head); | |
1852 | ||
1853 | err = 0; | |
1854 | done: | |
1855 | if (nr_underway == 0) { | |
1856 | /* | |
1857 | * The page was marked dirty, but the buffers were | |
1858 | * clean. Someone wrote them back by hand with | |
1859 | * ll_rw_block/submit_bh. A rare case. | |
1860 | */ | |
1861 | int uptodate = 1; | |
1862 | do { | |
1863 | if (!buffer_uptodate(bh)) { | |
1864 | uptodate = 0; | |
1865 | break; | |
1866 | } | |
1867 | bh = bh->b_this_page; | |
1868 | } while (bh != head); | |
1869 | if (uptodate) | |
1870 | SetPageUptodate(page); | |
1871 | end_page_writeback(page); | |
1872 | /* | |
1873 | * The page and buffer_heads can be released at any time from | |
1874 | * here on. | |
1875 | */ | |
1876 | wbc->pages_skipped++; /* We didn't write this page */ | |
1877 | } | |
1878 | return err; | |
1879 | ||
1880 | recover: | |
1881 | /* | |
1882 | * ENOSPC, or some other error. We may already have added some | |
1883 | * blocks to the file, so we need to write these out to avoid | |
1884 | * exposing stale data. | |
1885 | * The page is currently locked and not marked for writeback | |
1886 | */ | |
1887 | bh = head; | |
1888 | /* Recovery: lock and submit the mapped buffers */ | |
1889 | do { | |
1890 | get_bh(bh); | |
1891 | if (buffer_mapped(bh) && buffer_dirty(bh)) { | |
1892 | lock_buffer(bh); | |
1893 | mark_buffer_async_write(bh); | |
1894 | } else { | |
1895 | /* | |
1896 | * The buffer may have been set dirty during | |
1897 | * attachment to a dirty page. | |
1898 | */ | |
1899 | clear_buffer_dirty(bh); | |
1900 | } | |
1901 | } while ((bh = bh->b_this_page) != head); | |
1902 | SetPageError(page); | |
1903 | BUG_ON(PageWriteback(page)); | |
1904 | set_page_writeback(page); | |
1905 | unlock_page(page); | |
1906 | do { | |
1907 | struct buffer_head *next = bh->b_this_page; | |
1908 | if (buffer_async_write(bh)) { | |
1909 | clear_buffer_dirty(bh); | |
1910 | submit_bh(WRITE, bh); | |
1911 | nr_underway++; | |
1912 | } | |
1913 | put_bh(bh); | |
1914 | bh = next; | |
1915 | } while (bh != head); | |
1916 | goto done; | |
1917 | } | |
1918 | ||
1919 | static int __block_prepare_write(struct inode *inode, struct page *page, | |
1920 | unsigned from, unsigned to, get_block_t *get_block) | |
1921 | { | |
1922 | unsigned block_start, block_end; | |
1923 | sector_t block; | |
1924 | int err = 0; | |
1925 | unsigned blocksize, bbits; | |
1926 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1927 | ||
1928 | BUG_ON(!PageLocked(page)); | |
1929 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1930 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1931 | BUG_ON(from > to); | |
1932 | ||
1933 | blocksize = 1 << inode->i_blkbits; | |
1934 | if (!page_has_buffers(page)) | |
1935 | create_empty_buffers(page, blocksize, 0); | |
1936 | head = page_buffers(page); | |
1937 | ||
1938 | bbits = inode->i_blkbits; | |
1939 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1940 | ||
1941 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1942 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1943 | block_end = block_start + blocksize; | |
1944 | if (block_end <= from || block_start >= to) { | |
1945 | if (PageUptodate(page)) { | |
1946 | if (!buffer_uptodate(bh)) | |
1947 | set_buffer_uptodate(bh); | |
1948 | } | |
1949 | continue; | |
1950 | } | |
1951 | if (buffer_new(bh)) | |
1952 | clear_buffer_new(bh); | |
1953 | if (!buffer_mapped(bh)) { | |
1954 | err = get_block(inode, block, bh, 1); | |
1955 | if (err) | |
1956 | goto out; | |
1957 | if (buffer_new(bh)) { | |
1958 | clear_buffer_new(bh); | |
1959 | unmap_underlying_metadata(bh->b_bdev, | |
1960 | bh->b_blocknr); | |
1961 | if (PageUptodate(page)) { | |
1962 | set_buffer_uptodate(bh); | |
1963 | continue; | |
1964 | } | |
1965 | if (block_end > to || block_start < from) { | |
1966 | void *kaddr; | |
1967 | ||
1968 | kaddr = kmap_atomic(page, KM_USER0); | |
1969 | if (block_end > to) | |
1970 | memset(kaddr+to, 0, | |
1971 | block_end-to); | |
1972 | if (block_start < from) | |
1973 | memset(kaddr+block_start, | |
1974 | 0, from-block_start); | |
1975 | flush_dcache_page(page); | |
1976 | kunmap_atomic(kaddr, KM_USER0); | |
1977 | } | |
1978 | continue; | |
1979 | } | |
1980 | } | |
1981 | if (PageUptodate(page)) { | |
1982 | if (!buffer_uptodate(bh)) | |
1983 | set_buffer_uptodate(bh); | |
1984 | continue; | |
1985 | } | |
1986 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
1987 | (block_start < from || block_end > to)) { | |
1988 | ll_rw_block(READ, 1, &bh); | |
1989 | *wait_bh++=bh; | |
1990 | } | |
1991 | } | |
1992 | /* | |
1993 | * If we issued read requests - let them complete. | |
1994 | */ | |
1995 | while(wait_bh > wait) { | |
1996 | wait_on_buffer(*--wait_bh); | |
1997 | if (!buffer_uptodate(*wait_bh)) | |
1998 | return -EIO; | |
1999 | } | |
2000 | return 0; | |
2001 | out: | |
2002 | /* | |
2003 | * Zero out any newly allocated blocks to avoid exposing stale | |
2004 | * data. If BH_New is set, we know that the block was newly | |
2005 | * allocated in the above loop. | |
2006 | */ | |
2007 | bh = head; | |
2008 | block_start = 0; | |
2009 | do { | |
2010 | block_end = block_start+blocksize; | |
2011 | if (block_end <= from) | |
2012 | goto next_bh; | |
2013 | if (block_start >= to) | |
2014 | break; | |
2015 | if (buffer_new(bh)) { | |
2016 | void *kaddr; | |
2017 | ||
2018 | clear_buffer_new(bh); | |
2019 | kaddr = kmap_atomic(page, KM_USER0); | |
2020 | memset(kaddr+block_start, 0, bh->b_size); | |
2021 | kunmap_atomic(kaddr, KM_USER0); | |
2022 | set_buffer_uptodate(bh); | |
2023 | mark_buffer_dirty(bh); | |
2024 | } | |
2025 | next_bh: | |
2026 | block_start = block_end; | |
2027 | bh = bh->b_this_page; | |
2028 | } while (bh != head); | |
2029 | return err; | |
2030 | } | |
2031 | ||
2032 | static int __block_commit_write(struct inode *inode, struct page *page, | |
2033 | unsigned from, unsigned to) | |
2034 | { | |
2035 | unsigned block_start, block_end; | |
2036 | int partial = 0; | |
2037 | unsigned blocksize; | |
2038 | struct buffer_head *bh, *head; | |
2039 | ||
2040 | blocksize = 1 << inode->i_blkbits; | |
2041 | ||
2042 | for(bh = head = page_buffers(page), block_start = 0; | |
2043 | bh != head || !block_start; | |
2044 | block_start=block_end, bh = bh->b_this_page) { | |
2045 | block_end = block_start + blocksize; | |
2046 | if (block_end <= from || block_start >= to) { | |
2047 | if (!buffer_uptodate(bh)) | |
2048 | partial = 1; | |
2049 | } else { | |
2050 | set_buffer_uptodate(bh); | |
2051 | mark_buffer_dirty(bh); | |
2052 | } | |
2053 | } | |
2054 | ||
2055 | /* | |
2056 | * If this is a partial write which happened to make all buffers | |
2057 | * uptodate then we can optimize away a bogus readpage() for | |
2058 | * the next read(). Here we 'discover' whether the page went | |
2059 | * uptodate as a result of this (potentially partial) write. | |
2060 | */ | |
2061 | if (!partial) | |
2062 | SetPageUptodate(page); | |
2063 | return 0; | |
2064 | } | |
2065 | ||
2066 | /* | |
2067 | * Generic "read page" function for block devices that have the normal | |
2068 | * get_block functionality. This is most of the block device filesystems. | |
2069 | * Reads the page asynchronously --- the unlock_buffer() and | |
2070 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2071 | * page struct once IO has completed. | |
2072 | */ | |
2073 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2074 | { | |
2075 | struct inode *inode = page->mapping->host; | |
2076 | sector_t iblock, lblock; | |
2077 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
2078 | unsigned int blocksize; | |
2079 | int nr, i; | |
2080 | int fully_mapped = 1; | |
2081 | ||
cd7619d6 | 2082 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
2083 | blocksize = 1 << inode->i_blkbits; |
2084 | if (!page_has_buffers(page)) | |
2085 | create_empty_buffers(page, blocksize, 0); | |
2086 | head = page_buffers(page); | |
2087 | ||
2088 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
2089 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; | |
2090 | bh = head; | |
2091 | nr = 0; | |
2092 | i = 0; | |
2093 | ||
2094 | do { | |
2095 | if (buffer_uptodate(bh)) | |
2096 | continue; | |
2097 | ||
2098 | if (!buffer_mapped(bh)) { | |
2099 | fully_mapped = 0; | |
2100 | if (iblock < lblock) { | |
2101 | if (get_block(inode, iblock, bh, 0)) | |
2102 | SetPageError(page); | |
2103 | } | |
2104 | if (!buffer_mapped(bh)) { | |
2105 | void *kaddr = kmap_atomic(page, KM_USER0); | |
2106 | memset(kaddr + i * blocksize, 0, blocksize); | |
2107 | flush_dcache_page(page); | |
2108 | kunmap_atomic(kaddr, KM_USER0); | |
2109 | set_buffer_uptodate(bh); | |
2110 | continue; | |
2111 | } | |
2112 | /* | |
2113 | * get_block() might have updated the buffer | |
2114 | * synchronously | |
2115 | */ | |
2116 | if (buffer_uptodate(bh)) | |
2117 | continue; | |
2118 | } | |
2119 | arr[nr++] = bh; | |
2120 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2121 | ||
2122 | if (fully_mapped) | |
2123 | SetPageMappedToDisk(page); | |
2124 | ||
2125 | if (!nr) { | |
2126 | /* | |
2127 | * All buffers are uptodate - we can set the page uptodate | |
2128 | * as well. But not if get_block() returned an error. | |
2129 | */ | |
2130 | if (!PageError(page)) | |
2131 | SetPageUptodate(page); | |
2132 | unlock_page(page); | |
2133 | return 0; | |
2134 | } | |
2135 | ||
2136 | /* Stage two: lock the buffers */ | |
2137 | for (i = 0; i < nr; i++) { | |
2138 | bh = arr[i]; | |
2139 | lock_buffer(bh); | |
2140 | mark_buffer_async_read(bh); | |
2141 | } | |
2142 | ||
2143 | /* | |
2144 | * Stage 3: start the IO. Check for uptodateness | |
2145 | * inside the buffer lock in case another process reading | |
2146 | * the underlying blockdev brought it uptodate (the sct fix). | |
2147 | */ | |
2148 | for (i = 0; i < nr; i++) { | |
2149 | bh = arr[i]; | |
2150 | if (buffer_uptodate(bh)) | |
2151 | end_buffer_async_read(bh, 1); | |
2152 | else | |
2153 | submit_bh(READ, bh); | |
2154 | } | |
2155 | return 0; | |
2156 | } | |
2157 | ||
2158 | /* utility function for filesystems that need to do work on expanding | |
2159 | * truncates. Uses prepare/commit_write to allow the filesystem to | |
2160 | * deal with the hole. | |
2161 | */ | |
2162 | int generic_cont_expand(struct inode *inode, loff_t size) | |
2163 | { | |
2164 | struct address_space *mapping = inode->i_mapping; | |
2165 | struct page *page; | |
2166 | unsigned long index, offset, limit; | |
2167 | int err; | |
2168 | ||
2169 | err = -EFBIG; | |
2170 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
2171 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { | |
2172 | send_sig(SIGXFSZ, current, 0); | |
2173 | goto out; | |
2174 | } | |
2175 | if (size > inode->i_sb->s_maxbytes) | |
2176 | goto out; | |
2177 | ||
2178 | offset = (size & (PAGE_CACHE_SIZE-1)); /* Within page */ | |
2179 | ||
2180 | /* ugh. in prepare/commit_write, if from==to==start of block, we | |
2181 | ** skip the prepare. make sure we never send an offset for the start | |
2182 | ** of a block | |
2183 | */ | |
2184 | if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { | |
2185 | offset++; | |
2186 | } | |
2187 | index = size >> PAGE_CACHE_SHIFT; | |
2188 | err = -ENOMEM; | |
2189 | page = grab_cache_page(mapping, index); | |
2190 | if (!page) | |
2191 | goto out; | |
2192 | err = mapping->a_ops->prepare_write(NULL, page, offset, offset); | |
2193 | if (!err) { | |
2194 | err = mapping->a_ops->commit_write(NULL, page, offset, offset); | |
2195 | } | |
2196 | unlock_page(page); | |
2197 | page_cache_release(page); | |
2198 | if (err > 0) | |
2199 | err = 0; | |
2200 | out: | |
2201 | return err; | |
2202 | } | |
2203 | ||
2204 | /* | |
2205 | * For moronic filesystems that do not allow holes in file. | |
2206 | * We may have to extend the file. | |
2207 | */ | |
2208 | ||
2209 | int cont_prepare_write(struct page *page, unsigned offset, | |
2210 | unsigned to, get_block_t *get_block, loff_t *bytes) | |
2211 | { | |
2212 | struct address_space *mapping = page->mapping; | |
2213 | struct inode *inode = mapping->host; | |
2214 | struct page *new_page; | |
2215 | pgoff_t pgpos; | |
2216 | long status; | |
2217 | unsigned zerofrom; | |
2218 | unsigned blocksize = 1 << inode->i_blkbits; | |
2219 | void *kaddr; | |
2220 | ||
2221 | while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { | |
2222 | status = -ENOMEM; | |
2223 | new_page = grab_cache_page(mapping, pgpos); | |
2224 | if (!new_page) | |
2225 | goto out; | |
2226 | /* we might sleep */ | |
2227 | if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { | |
2228 | unlock_page(new_page); | |
2229 | page_cache_release(new_page); | |
2230 | continue; | |
2231 | } | |
2232 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2233 | if (zerofrom & (blocksize-1)) { | |
2234 | *bytes |= (blocksize-1); | |
2235 | (*bytes)++; | |
2236 | } | |
2237 | status = __block_prepare_write(inode, new_page, zerofrom, | |
2238 | PAGE_CACHE_SIZE, get_block); | |
2239 | if (status) | |
2240 | goto out_unmap; | |
2241 | kaddr = kmap_atomic(new_page, KM_USER0); | |
2242 | memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); | |
2243 | flush_dcache_page(new_page); | |
2244 | kunmap_atomic(kaddr, KM_USER0); | |
2245 | generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); | |
2246 | unlock_page(new_page); | |
2247 | page_cache_release(new_page); | |
2248 | } | |
2249 | ||
2250 | if (page->index < pgpos) { | |
2251 | /* completely inside the area */ | |
2252 | zerofrom = offset; | |
2253 | } else { | |
2254 | /* page covers the boundary, find the boundary offset */ | |
2255 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2256 | ||
2257 | /* if we will expand the thing last block will be filled */ | |
2258 | if (to > zerofrom && (zerofrom & (blocksize-1))) { | |
2259 | *bytes |= (blocksize-1); | |
2260 | (*bytes)++; | |
2261 | } | |
2262 | ||
2263 | /* starting below the boundary? Nothing to zero out */ | |
2264 | if (offset <= zerofrom) | |
2265 | zerofrom = offset; | |
2266 | } | |
2267 | status = __block_prepare_write(inode, page, zerofrom, to, get_block); | |
2268 | if (status) | |
2269 | goto out1; | |
2270 | if (zerofrom < offset) { | |
2271 | kaddr = kmap_atomic(page, KM_USER0); | |
2272 | memset(kaddr+zerofrom, 0, offset-zerofrom); | |
2273 | flush_dcache_page(page); | |
2274 | kunmap_atomic(kaddr, KM_USER0); | |
2275 | __block_commit_write(inode, page, zerofrom, offset); | |
2276 | } | |
2277 | return 0; | |
2278 | out1: | |
2279 | ClearPageUptodate(page); | |
2280 | return status; | |
2281 | ||
2282 | out_unmap: | |
2283 | ClearPageUptodate(new_page); | |
2284 | unlock_page(new_page); | |
2285 | page_cache_release(new_page); | |
2286 | out: | |
2287 | return status; | |
2288 | } | |
2289 | ||
2290 | int block_prepare_write(struct page *page, unsigned from, unsigned to, | |
2291 | get_block_t *get_block) | |
2292 | { | |
2293 | struct inode *inode = page->mapping->host; | |
2294 | int err = __block_prepare_write(inode, page, from, to, get_block); | |
2295 | if (err) | |
2296 | ClearPageUptodate(page); | |
2297 | return err; | |
2298 | } | |
2299 | ||
2300 | int block_commit_write(struct page *page, unsigned from, unsigned to) | |
2301 | { | |
2302 | struct inode *inode = page->mapping->host; | |
2303 | __block_commit_write(inode,page,from,to); | |
2304 | return 0; | |
2305 | } | |
2306 | ||
2307 | int generic_commit_write(struct file *file, struct page *page, | |
2308 | unsigned from, unsigned to) | |
2309 | { | |
2310 | struct inode *inode = page->mapping->host; | |
2311 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2312 | __block_commit_write(inode,page,from,to); | |
2313 | /* | |
2314 | * No need to use i_size_read() here, the i_size | |
2315 | * cannot change under us because we hold i_sem. | |
2316 | */ | |
2317 | if (pos > inode->i_size) { | |
2318 | i_size_write(inode, pos); | |
2319 | mark_inode_dirty(inode); | |
2320 | } | |
2321 | return 0; | |
2322 | } | |
2323 | ||
2324 | ||
2325 | /* | |
2326 | * nobh_prepare_write()'s prereads are special: the buffer_heads are freed | |
2327 | * immediately, while under the page lock. So it needs a special end_io | |
2328 | * handler which does not touch the bh after unlocking it. | |
2329 | * | |
2330 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
2331 | * a race there is benign: unlock_buffer() only use the bh's address for | |
2332 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
2333 | * itself. | |
2334 | */ | |
2335 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2336 | { | |
2337 | if (uptodate) { | |
2338 | set_buffer_uptodate(bh); | |
2339 | } else { | |
2340 | /* This happens, due to failed READA attempts. */ | |
2341 | clear_buffer_uptodate(bh); | |
2342 | } | |
2343 | unlock_buffer(bh); | |
2344 | } | |
2345 | ||
2346 | /* | |
2347 | * On entry, the page is fully not uptodate. | |
2348 | * On exit the page is fully uptodate in the areas outside (from,to) | |
2349 | */ | |
2350 | int nobh_prepare_write(struct page *page, unsigned from, unsigned to, | |
2351 | get_block_t *get_block) | |
2352 | { | |
2353 | struct inode *inode = page->mapping->host; | |
2354 | const unsigned blkbits = inode->i_blkbits; | |
2355 | const unsigned blocksize = 1 << blkbits; | |
2356 | struct buffer_head map_bh; | |
2357 | struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; | |
2358 | unsigned block_in_page; | |
2359 | unsigned block_start; | |
2360 | sector_t block_in_file; | |
2361 | char *kaddr; | |
2362 | int nr_reads = 0; | |
2363 | int i; | |
2364 | int ret = 0; | |
2365 | int is_mapped_to_disk = 1; | |
2366 | int dirtied_it = 0; | |
2367 | ||
2368 | if (PageMappedToDisk(page)) | |
2369 | return 0; | |
2370 | ||
2371 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); | |
2372 | map_bh.b_page = page; | |
2373 | ||
2374 | /* | |
2375 | * We loop across all blocks in the page, whether or not they are | |
2376 | * part of the affected region. This is so we can discover if the | |
2377 | * page is fully mapped-to-disk. | |
2378 | */ | |
2379 | for (block_start = 0, block_in_page = 0; | |
2380 | block_start < PAGE_CACHE_SIZE; | |
2381 | block_in_page++, block_start += blocksize) { | |
2382 | unsigned block_end = block_start + blocksize; | |
2383 | int create; | |
2384 | ||
2385 | map_bh.b_state = 0; | |
2386 | create = 1; | |
2387 | if (block_start >= to) | |
2388 | create = 0; | |
2389 | ret = get_block(inode, block_in_file + block_in_page, | |
2390 | &map_bh, create); | |
2391 | if (ret) | |
2392 | goto failed; | |
2393 | if (!buffer_mapped(&map_bh)) | |
2394 | is_mapped_to_disk = 0; | |
2395 | if (buffer_new(&map_bh)) | |
2396 | unmap_underlying_metadata(map_bh.b_bdev, | |
2397 | map_bh.b_blocknr); | |
2398 | if (PageUptodate(page)) | |
2399 | continue; | |
2400 | if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { | |
2401 | kaddr = kmap_atomic(page, KM_USER0); | |
2402 | if (block_start < from) { | |
2403 | memset(kaddr+block_start, 0, from-block_start); | |
2404 | dirtied_it = 1; | |
2405 | } | |
2406 | if (block_end > to) { | |
2407 | memset(kaddr + to, 0, block_end - to); | |
2408 | dirtied_it = 1; | |
2409 | } | |
2410 | flush_dcache_page(page); | |
2411 | kunmap_atomic(kaddr, KM_USER0); | |
2412 | continue; | |
2413 | } | |
2414 | if (buffer_uptodate(&map_bh)) | |
2415 | continue; /* reiserfs does this */ | |
2416 | if (block_start < from || block_end > to) { | |
2417 | struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); | |
2418 | ||
2419 | if (!bh) { | |
2420 | ret = -ENOMEM; | |
2421 | goto failed; | |
2422 | } | |
2423 | bh->b_state = map_bh.b_state; | |
2424 | atomic_set(&bh->b_count, 0); | |
2425 | bh->b_this_page = NULL; | |
2426 | bh->b_page = page; | |
2427 | bh->b_blocknr = map_bh.b_blocknr; | |
2428 | bh->b_size = blocksize; | |
2429 | bh->b_data = (char *)(long)block_start; | |
2430 | bh->b_bdev = map_bh.b_bdev; | |
2431 | bh->b_private = NULL; | |
2432 | read_bh[nr_reads++] = bh; | |
2433 | } | |
2434 | } | |
2435 | ||
2436 | if (nr_reads) { | |
2437 | struct buffer_head *bh; | |
2438 | ||
2439 | /* | |
2440 | * The page is locked, so these buffers are protected from | |
2441 | * any VM or truncate activity. Hence we don't need to care | |
2442 | * for the buffer_head refcounts. | |
2443 | */ | |
2444 | for (i = 0; i < nr_reads; i++) { | |
2445 | bh = read_bh[i]; | |
2446 | lock_buffer(bh); | |
2447 | bh->b_end_io = end_buffer_read_nobh; | |
2448 | submit_bh(READ, bh); | |
2449 | } | |
2450 | for (i = 0; i < nr_reads; i++) { | |
2451 | bh = read_bh[i]; | |
2452 | wait_on_buffer(bh); | |
2453 | if (!buffer_uptodate(bh)) | |
2454 | ret = -EIO; | |
2455 | free_buffer_head(bh); | |
2456 | read_bh[i] = NULL; | |
2457 | } | |
2458 | if (ret) | |
2459 | goto failed; | |
2460 | } | |
2461 | ||
2462 | if (is_mapped_to_disk) | |
2463 | SetPageMappedToDisk(page); | |
2464 | SetPageUptodate(page); | |
2465 | ||
2466 | /* | |
2467 | * Setting the page dirty here isn't necessary for the prepare_write | |
2468 | * function - commit_write will do that. But if/when this function is | |
2469 | * used within the pagefault handler to ensure that all mmapped pages | |
2470 | * have backing space in the filesystem, we will need to dirty the page | |
2471 | * if its contents were altered. | |
2472 | */ | |
2473 | if (dirtied_it) | |
2474 | set_page_dirty(page); | |
2475 | ||
2476 | return 0; | |
2477 | ||
2478 | failed: | |
2479 | for (i = 0; i < nr_reads; i++) { | |
2480 | if (read_bh[i]) | |
2481 | free_buffer_head(read_bh[i]); | |
2482 | } | |
2483 | ||
2484 | /* | |
2485 | * Error recovery is pretty slack. Clear the page and mark it dirty | |
2486 | * so we'll later zero out any blocks which _were_ allocated. | |
2487 | */ | |
2488 | kaddr = kmap_atomic(page, KM_USER0); | |
2489 | memset(kaddr, 0, PAGE_CACHE_SIZE); | |
2490 | kunmap_atomic(kaddr, KM_USER0); | |
2491 | SetPageUptodate(page); | |
2492 | set_page_dirty(page); | |
2493 | return ret; | |
2494 | } | |
2495 | EXPORT_SYMBOL(nobh_prepare_write); | |
2496 | ||
2497 | int nobh_commit_write(struct file *file, struct page *page, | |
2498 | unsigned from, unsigned to) | |
2499 | { | |
2500 | struct inode *inode = page->mapping->host; | |
2501 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2502 | ||
2503 | set_page_dirty(page); | |
2504 | if (pos > inode->i_size) { | |
2505 | i_size_write(inode, pos); | |
2506 | mark_inode_dirty(inode); | |
2507 | } | |
2508 | return 0; | |
2509 | } | |
2510 | EXPORT_SYMBOL(nobh_commit_write); | |
2511 | ||
2512 | /* | |
2513 | * nobh_writepage() - based on block_full_write_page() except | |
2514 | * that it tries to operate without attaching bufferheads to | |
2515 | * the page. | |
2516 | */ | |
2517 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2518 | struct writeback_control *wbc) | |
2519 | { | |
2520 | struct inode * const inode = page->mapping->host; | |
2521 | loff_t i_size = i_size_read(inode); | |
2522 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2523 | unsigned offset; | |
2524 | void *kaddr; | |
2525 | int ret; | |
2526 | ||
2527 | /* Is the page fully inside i_size? */ | |
2528 | if (page->index < end_index) | |
2529 | goto out; | |
2530 | ||
2531 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2532 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2533 | if (page->index >= end_index+1 || !offset) { | |
2534 | /* | |
2535 | * The page may have dirty, unmapped buffers. For example, | |
2536 | * they may have been added in ext3_writepage(). Make them | |
2537 | * freeable here, so the page does not leak. | |
2538 | */ | |
2539 | #if 0 | |
2540 | /* Not really sure about this - do we need this ? */ | |
2541 | if (page->mapping->a_ops->invalidatepage) | |
2542 | page->mapping->a_ops->invalidatepage(page, offset); | |
2543 | #endif | |
2544 | unlock_page(page); | |
2545 | return 0; /* don't care */ | |
2546 | } | |
2547 | ||
2548 | /* | |
2549 | * The page straddles i_size. It must be zeroed out on each and every | |
2550 | * writepage invocation because it may be mmapped. "A file is mapped | |
2551 | * in multiples of the page size. For a file that is not a multiple of | |
2552 | * the page size, the remaining memory is zeroed when mapped, and | |
2553 | * writes to that region are not written out to the file." | |
2554 | */ | |
2555 | kaddr = kmap_atomic(page, KM_USER0); | |
2556 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2557 | flush_dcache_page(page); | |
2558 | kunmap_atomic(kaddr, KM_USER0); | |
2559 | out: | |
2560 | ret = mpage_writepage(page, get_block, wbc); | |
2561 | if (ret == -EAGAIN) | |
2562 | ret = __block_write_full_page(inode, page, get_block, wbc); | |
2563 | return ret; | |
2564 | } | |
2565 | EXPORT_SYMBOL(nobh_writepage); | |
2566 | ||
2567 | /* | |
2568 | * This function assumes that ->prepare_write() uses nobh_prepare_write(). | |
2569 | */ | |
2570 | int nobh_truncate_page(struct address_space *mapping, loff_t from) | |
2571 | { | |
2572 | struct inode *inode = mapping->host; | |
2573 | unsigned blocksize = 1 << inode->i_blkbits; | |
2574 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2575 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2576 | unsigned to; | |
2577 | struct page *page; | |
2578 | struct address_space_operations *a_ops = mapping->a_ops; | |
2579 | char *kaddr; | |
2580 | int ret = 0; | |
2581 | ||
2582 | if ((offset & (blocksize - 1)) == 0) | |
2583 | goto out; | |
2584 | ||
2585 | ret = -ENOMEM; | |
2586 | page = grab_cache_page(mapping, index); | |
2587 | if (!page) | |
2588 | goto out; | |
2589 | ||
2590 | to = (offset + blocksize) & ~(blocksize - 1); | |
2591 | ret = a_ops->prepare_write(NULL, page, offset, to); | |
2592 | if (ret == 0) { | |
2593 | kaddr = kmap_atomic(page, KM_USER0); | |
2594 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2595 | flush_dcache_page(page); | |
2596 | kunmap_atomic(kaddr, KM_USER0); | |
2597 | set_page_dirty(page); | |
2598 | } | |
2599 | unlock_page(page); | |
2600 | page_cache_release(page); | |
2601 | out: | |
2602 | return ret; | |
2603 | } | |
2604 | EXPORT_SYMBOL(nobh_truncate_page); | |
2605 | ||
2606 | int block_truncate_page(struct address_space *mapping, | |
2607 | loff_t from, get_block_t *get_block) | |
2608 | { | |
2609 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2610 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2611 | unsigned blocksize; | |
2612 | pgoff_t iblock; | |
2613 | unsigned length, pos; | |
2614 | struct inode *inode = mapping->host; | |
2615 | struct page *page; | |
2616 | struct buffer_head *bh; | |
2617 | void *kaddr; | |
2618 | int err; | |
2619 | ||
2620 | blocksize = 1 << inode->i_blkbits; | |
2621 | length = offset & (blocksize - 1); | |
2622 | ||
2623 | /* Block boundary? Nothing to do */ | |
2624 | if (!length) | |
2625 | return 0; | |
2626 | ||
2627 | length = blocksize - length; | |
2628 | iblock = index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
2629 | ||
2630 | page = grab_cache_page(mapping, index); | |
2631 | err = -ENOMEM; | |
2632 | if (!page) | |
2633 | goto out; | |
2634 | ||
2635 | if (!page_has_buffers(page)) | |
2636 | create_empty_buffers(page, blocksize, 0); | |
2637 | ||
2638 | /* Find the buffer that contains "offset" */ | |
2639 | bh = page_buffers(page); | |
2640 | pos = blocksize; | |
2641 | while (offset >= pos) { | |
2642 | bh = bh->b_this_page; | |
2643 | iblock++; | |
2644 | pos += blocksize; | |
2645 | } | |
2646 | ||
2647 | err = 0; | |
2648 | if (!buffer_mapped(bh)) { | |
2649 | err = get_block(inode, iblock, bh, 0); | |
2650 | if (err) | |
2651 | goto unlock; | |
2652 | /* unmapped? It's a hole - nothing to do */ | |
2653 | if (!buffer_mapped(bh)) | |
2654 | goto unlock; | |
2655 | } | |
2656 | ||
2657 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2658 | if (PageUptodate(page)) | |
2659 | set_buffer_uptodate(bh); | |
2660 | ||
2661 | if (!buffer_uptodate(bh) && !buffer_delay(bh)) { | |
2662 | err = -EIO; | |
2663 | ll_rw_block(READ, 1, &bh); | |
2664 | wait_on_buffer(bh); | |
2665 | /* Uhhuh. Read error. Complain and punt. */ | |
2666 | if (!buffer_uptodate(bh)) | |
2667 | goto unlock; | |
2668 | } | |
2669 | ||
2670 | kaddr = kmap_atomic(page, KM_USER0); | |
2671 | memset(kaddr + offset, 0, length); | |
2672 | flush_dcache_page(page); | |
2673 | kunmap_atomic(kaddr, KM_USER0); | |
2674 | ||
2675 | mark_buffer_dirty(bh); | |
2676 | err = 0; | |
2677 | ||
2678 | unlock: | |
2679 | unlock_page(page); | |
2680 | page_cache_release(page); | |
2681 | out: | |
2682 | return err; | |
2683 | } | |
2684 | ||
2685 | /* | |
2686 | * The generic ->writepage function for buffer-backed address_spaces | |
2687 | */ | |
2688 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2689 | struct writeback_control *wbc) | |
2690 | { | |
2691 | struct inode * const inode = page->mapping->host; | |
2692 | loff_t i_size = i_size_read(inode); | |
2693 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2694 | unsigned offset; | |
2695 | void *kaddr; | |
2696 | ||
2697 | /* Is the page fully inside i_size? */ | |
2698 | if (page->index < end_index) | |
2699 | return __block_write_full_page(inode, page, get_block, wbc); | |
2700 | ||
2701 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2702 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2703 | if (page->index >= end_index+1 || !offset) { | |
2704 | /* | |
2705 | * The page may have dirty, unmapped buffers. For example, | |
2706 | * they may have been added in ext3_writepage(). Make them | |
2707 | * freeable here, so the page does not leak. | |
2708 | */ | |
2709 | block_invalidatepage(page, 0); | |
2710 | unlock_page(page); | |
2711 | return 0; /* don't care */ | |
2712 | } | |
2713 | ||
2714 | /* | |
2715 | * The page straddles i_size. It must be zeroed out on each and every | |
2716 | * writepage invokation because it may be mmapped. "A file is mapped | |
2717 | * in multiples of the page size. For a file that is not a multiple of | |
2718 | * the page size, the remaining memory is zeroed when mapped, and | |
2719 | * writes to that region are not written out to the file." | |
2720 | */ | |
2721 | kaddr = kmap_atomic(page, KM_USER0); | |
2722 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2723 | flush_dcache_page(page); | |
2724 | kunmap_atomic(kaddr, KM_USER0); | |
2725 | return __block_write_full_page(inode, page, get_block, wbc); | |
2726 | } | |
2727 | ||
2728 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, | |
2729 | get_block_t *get_block) | |
2730 | { | |
2731 | struct buffer_head tmp; | |
2732 | struct inode *inode = mapping->host; | |
2733 | tmp.b_state = 0; | |
2734 | tmp.b_blocknr = 0; | |
2735 | get_block(inode, block, &tmp, 0); | |
2736 | return tmp.b_blocknr; | |
2737 | } | |
2738 | ||
2739 | static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) | |
2740 | { | |
2741 | struct buffer_head *bh = bio->bi_private; | |
2742 | ||
2743 | if (bio->bi_size) | |
2744 | return 1; | |
2745 | ||
2746 | if (err == -EOPNOTSUPP) { | |
2747 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
2748 | set_bit(BH_Eopnotsupp, &bh->b_state); | |
2749 | } | |
2750 | ||
2751 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); | |
2752 | bio_put(bio); | |
2753 | return 0; | |
2754 | } | |
2755 | ||
2756 | int submit_bh(int rw, struct buffer_head * bh) | |
2757 | { | |
2758 | struct bio *bio; | |
2759 | int ret = 0; | |
2760 | ||
2761 | BUG_ON(!buffer_locked(bh)); | |
2762 | BUG_ON(!buffer_mapped(bh)); | |
2763 | BUG_ON(!bh->b_end_io); | |
2764 | ||
2765 | if (buffer_ordered(bh) && (rw == WRITE)) | |
2766 | rw = WRITE_BARRIER; | |
2767 | ||
2768 | /* | |
2769 | * Only clear out a write error when rewriting, should this | |
2770 | * include WRITE_SYNC as well? | |
2771 | */ | |
2772 | if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) | |
2773 | clear_buffer_write_io_error(bh); | |
2774 | ||
2775 | /* | |
2776 | * from here on down, it's all bio -- do the initial mapping, | |
2777 | * submit_bio -> generic_make_request may further map this bio around | |
2778 | */ | |
2779 | bio = bio_alloc(GFP_NOIO, 1); | |
2780 | ||
2781 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2782 | bio->bi_bdev = bh->b_bdev; | |
2783 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2784 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2785 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2786 | ||
2787 | bio->bi_vcnt = 1; | |
2788 | bio->bi_idx = 0; | |
2789 | bio->bi_size = bh->b_size; | |
2790 | ||
2791 | bio->bi_end_io = end_bio_bh_io_sync; | |
2792 | bio->bi_private = bh; | |
2793 | ||
2794 | bio_get(bio); | |
2795 | submit_bio(rw, bio); | |
2796 | ||
2797 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2798 | ret = -EOPNOTSUPP; | |
2799 | ||
2800 | bio_put(bio); | |
2801 | return ret; | |
2802 | } | |
2803 | ||
2804 | /** | |
2805 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
2806 | * @rw: whether to %READ or %WRITE or maybe %READA (readahead) | |
2807 | * @nr: number of &struct buffer_heads in the array | |
2808 | * @bhs: array of pointers to &struct buffer_head | |
2809 | * | |
2810 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, | |
2811 | * and requests an I/O operation on them, either a %READ or a %WRITE. | |
2812 | * The third %READA option is described in the documentation for | |
2813 | * generic_make_request() which ll_rw_block() calls. | |
2814 | * | |
2815 | * This function drops any buffer that it cannot get a lock on (with the | |
2816 | * BH_Lock state bit), any buffer that appears to be clean when doing a | |
2817 | * write request, and any buffer that appears to be up-to-date when doing | |
2818 | * read request. Further it marks as clean buffers that are processed for | |
2819 | * writing (the buffer cache won't assume that they are actually clean until | |
2820 | * the buffer gets unlocked). | |
2821 | * | |
2822 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
2823 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
2824 | * any waiters. | |
2825 | * | |
2826 | * All of the buffers must be for the same device, and must also be a | |
2827 | * multiple of the current approved size for the device. | |
2828 | */ | |
2829 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
2830 | { | |
2831 | int i; | |
2832 | ||
2833 | for (i = 0; i < nr; i++) { | |
2834 | struct buffer_head *bh = bhs[i]; | |
2835 | ||
2836 | if (test_set_buffer_locked(bh)) | |
2837 | continue; | |
2838 | ||
2839 | get_bh(bh); | |
2840 | if (rw == WRITE) { | |
1da177e4 | 2841 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 2842 | bh->b_end_io = end_buffer_write_sync; |
1da177e4 LT |
2843 | submit_bh(WRITE, bh); |
2844 | continue; | |
2845 | } | |
2846 | } else { | |
1da177e4 | 2847 | if (!buffer_uptodate(bh)) { |
76c3073a | 2848 | bh->b_end_io = end_buffer_read_sync; |
1da177e4 LT |
2849 | submit_bh(rw, bh); |
2850 | continue; | |
2851 | } | |
2852 | } | |
2853 | unlock_buffer(bh); | |
2854 | put_bh(bh); | |
2855 | } | |
2856 | } | |
2857 | ||
2858 | /* | |
2859 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
2860 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
2861 | * the buffer_head. | |
2862 | */ | |
2863 | int sync_dirty_buffer(struct buffer_head *bh) | |
2864 | { | |
2865 | int ret = 0; | |
2866 | ||
2867 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
2868 | lock_buffer(bh); | |
2869 | if (test_clear_buffer_dirty(bh)) { | |
2870 | get_bh(bh); | |
2871 | bh->b_end_io = end_buffer_write_sync; | |
2872 | ret = submit_bh(WRITE, bh); | |
2873 | wait_on_buffer(bh); | |
2874 | if (buffer_eopnotsupp(bh)) { | |
2875 | clear_buffer_eopnotsupp(bh); | |
2876 | ret = -EOPNOTSUPP; | |
2877 | } | |
2878 | if (!ret && !buffer_uptodate(bh)) | |
2879 | ret = -EIO; | |
2880 | } else { | |
2881 | unlock_buffer(bh); | |
2882 | } | |
2883 | return ret; | |
2884 | } | |
2885 | ||
2886 | /* | |
2887 | * try_to_free_buffers() checks if all the buffers on this particular page | |
2888 | * are unused, and releases them if so. | |
2889 | * | |
2890 | * Exclusion against try_to_free_buffers may be obtained by either | |
2891 | * locking the page or by holding its mapping's private_lock. | |
2892 | * | |
2893 | * If the page is dirty but all the buffers are clean then we need to | |
2894 | * be sure to mark the page clean as well. This is because the page | |
2895 | * may be against a block device, and a later reattachment of buffers | |
2896 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
2897 | * filesystem data on the same device. | |
2898 | * | |
2899 | * The same applies to regular filesystem pages: if all the buffers are | |
2900 | * clean then we set the page clean and proceed. To do that, we require | |
2901 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
2902 | * private_lock. | |
2903 | * | |
2904 | * try_to_free_buffers() is non-blocking. | |
2905 | */ | |
2906 | static inline int buffer_busy(struct buffer_head *bh) | |
2907 | { | |
2908 | return atomic_read(&bh->b_count) | | |
2909 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
2910 | } | |
2911 | ||
2912 | static int | |
2913 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
2914 | { | |
2915 | struct buffer_head *head = page_buffers(page); | |
2916 | struct buffer_head *bh; | |
2917 | ||
2918 | bh = head; | |
2919 | do { | |
de7d5a3b | 2920 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
2921 | set_bit(AS_EIO, &page->mapping->flags); |
2922 | if (buffer_busy(bh)) | |
2923 | goto failed; | |
2924 | bh = bh->b_this_page; | |
2925 | } while (bh != head); | |
2926 | ||
2927 | do { | |
2928 | struct buffer_head *next = bh->b_this_page; | |
2929 | ||
2930 | if (!list_empty(&bh->b_assoc_buffers)) | |
2931 | __remove_assoc_queue(bh); | |
2932 | bh = next; | |
2933 | } while (bh != head); | |
2934 | *buffers_to_free = head; | |
2935 | __clear_page_buffers(page); | |
2936 | return 1; | |
2937 | failed: | |
2938 | return 0; | |
2939 | } | |
2940 | ||
2941 | int try_to_free_buffers(struct page *page) | |
2942 | { | |
2943 | struct address_space * const mapping = page->mapping; | |
2944 | struct buffer_head *buffers_to_free = NULL; | |
2945 | int ret = 0; | |
2946 | ||
2947 | BUG_ON(!PageLocked(page)); | |
2948 | if (PageWriteback(page)) | |
2949 | return 0; | |
2950 | ||
2951 | if (mapping == NULL) { /* can this still happen? */ | |
2952 | ret = drop_buffers(page, &buffers_to_free); | |
2953 | goto out; | |
2954 | } | |
2955 | ||
2956 | spin_lock(&mapping->private_lock); | |
2957 | ret = drop_buffers(page, &buffers_to_free); | |
2958 | if (ret) { | |
2959 | /* | |
2960 | * If the filesystem writes its buffers by hand (eg ext3) | |
2961 | * then we can have clean buffers against a dirty page. We | |
2962 | * clean the page here; otherwise later reattachment of buffers | |
2963 | * could encounter a non-uptodate page, which is unresolvable. | |
2964 | * This only applies in the rare case where try_to_free_buffers | |
2965 | * succeeds but the page is not freed. | |
2966 | */ | |
2967 | clear_page_dirty(page); | |
2968 | } | |
2969 | spin_unlock(&mapping->private_lock); | |
2970 | out: | |
2971 | if (buffers_to_free) { | |
2972 | struct buffer_head *bh = buffers_to_free; | |
2973 | ||
2974 | do { | |
2975 | struct buffer_head *next = bh->b_this_page; | |
2976 | free_buffer_head(bh); | |
2977 | bh = next; | |
2978 | } while (bh != buffers_to_free); | |
2979 | } | |
2980 | return ret; | |
2981 | } | |
2982 | EXPORT_SYMBOL(try_to_free_buffers); | |
2983 | ||
2984 | int block_sync_page(struct page *page) | |
2985 | { | |
2986 | struct address_space *mapping; | |
2987 | ||
2988 | smp_mb(); | |
2989 | mapping = page_mapping(page); | |
2990 | if (mapping) | |
2991 | blk_run_backing_dev(mapping->backing_dev_info, page); | |
2992 | return 0; | |
2993 | } | |
2994 | ||
2995 | /* | |
2996 | * There are no bdflush tunables left. But distributions are | |
2997 | * still running obsolete flush daemons, so we terminate them here. | |
2998 | * | |
2999 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
3000 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. | |
3001 | */ | |
3002 | asmlinkage long sys_bdflush(int func, long data) | |
3003 | { | |
3004 | static int msg_count; | |
3005 | ||
3006 | if (!capable(CAP_SYS_ADMIN)) | |
3007 | return -EPERM; | |
3008 | ||
3009 | if (msg_count < 5) { | |
3010 | msg_count++; | |
3011 | printk(KERN_INFO | |
3012 | "warning: process `%s' used the obsolete bdflush" | |
3013 | " system call\n", current->comm); | |
3014 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3015 | } | |
3016 | ||
3017 | if (func == 1) | |
3018 | do_exit(0); | |
3019 | return 0; | |
3020 | } | |
3021 | ||
3022 | /* | |
3023 | * Buffer-head allocation | |
3024 | */ | |
3025 | static kmem_cache_t *bh_cachep; | |
3026 | ||
3027 | /* | |
3028 | * Once the number of bh's in the machine exceeds this level, we start | |
3029 | * stripping them in writeback. | |
3030 | */ | |
3031 | static int max_buffer_heads; | |
3032 | ||
3033 | int buffer_heads_over_limit; | |
3034 | ||
3035 | struct bh_accounting { | |
3036 | int nr; /* Number of live bh's */ | |
3037 | int ratelimit; /* Limit cacheline bouncing */ | |
3038 | }; | |
3039 | ||
3040 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3041 | ||
3042 | static void recalc_bh_state(void) | |
3043 | { | |
3044 | int i; | |
3045 | int tot = 0; | |
3046 | ||
3047 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) | |
3048 | return; | |
3049 | __get_cpu_var(bh_accounting).ratelimit = 0; | |
3050 | for_each_cpu(i) | |
3051 | tot += per_cpu(bh_accounting, i).nr; | |
3052 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3053 | } | |
3054 | ||
3055 | struct buffer_head *alloc_buffer_head(unsigned int __nocast gfp_flags) | |
3056 | { | |
3057 | struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); | |
3058 | if (ret) { | |
3059 | preempt_disable(); | |
3060 | __get_cpu_var(bh_accounting).nr++; | |
3061 | recalc_bh_state(); | |
3062 | preempt_enable(); | |
3063 | } | |
3064 | return ret; | |
3065 | } | |
3066 | EXPORT_SYMBOL(alloc_buffer_head); | |
3067 | ||
3068 | void free_buffer_head(struct buffer_head *bh) | |
3069 | { | |
3070 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3071 | kmem_cache_free(bh_cachep, bh); | |
3072 | preempt_disable(); | |
3073 | __get_cpu_var(bh_accounting).nr--; | |
3074 | recalc_bh_state(); | |
3075 | preempt_enable(); | |
3076 | } | |
3077 | EXPORT_SYMBOL(free_buffer_head); | |
3078 | ||
3079 | static void | |
3080 | init_buffer_head(void *data, kmem_cache_t *cachep, unsigned long flags) | |
3081 | { | |
3082 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == | |
3083 | SLAB_CTOR_CONSTRUCTOR) { | |
3084 | struct buffer_head * bh = (struct buffer_head *)data; | |
3085 | ||
3086 | memset(bh, 0, sizeof(*bh)); | |
3087 | INIT_LIST_HEAD(&bh->b_assoc_buffers); | |
3088 | } | |
3089 | } | |
3090 | ||
3091 | #ifdef CONFIG_HOTPLUG_CPU | |
3092 | static void buffer_exit_cpu(int cpu) | |
3093 | { | |
3094 | int i; | |
3095 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3096 | ||
3097 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3098 | brelse(b->bhs[i]); | |
3099 | b->bhs[i] = NULL; | |
3100 | } | |
3101 | } | |
3102 | ||
3103 | static int buffer_cpu_notify(struct notifier_block *self, | |
3104 | unsigned long action, void *hcpu) | |
3105 | { | |
3106 | if (action == CPU_DEAD) | |
3107 | buffer_exit_cpu((unsigned long)hcpu); | |
3108 | return NOTIFY_OK; | |
3109 | } | |
3110 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3111 | ||
3112 | void __init buffer_init(void) | |
3113 | { | |
3114 | int nrpages; | |
3115 | ||
3116 | bh_cachep = kmem_cache_create("buffer_head", | |
3117 | sizeof(struct buffer_head), 0, | |
3118 | SLAB_PANIC, init_buffer_head, NULL); | |
3119 | ||
3120 | /* | |
3121 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3122 | */ | |
3123 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3124 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3125 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3126 | } | |
3127 | ||
3128 | EXPORT_SYMBOL(__bforget); | |
3129 | EXPORT_SYMBOL(__brelse); | |
3130 | EXPORT_SYMBOL(__wait_on_buffer); | |
3131 | EXPORT_SYMBOL(block_commit_write); | |
3132 | EXPORT_SYMBOL(block_prepare_write); | |
3133 | EXPORT_SYMBOL(block_read_full_page); | |
3134 | EXPORT_SYMBOL(block_sync_page); | |
3135 | EXPORT_SYMBOL(block_truncate_page); | |
3136 | EXPORT_SYMBOL(block_write_full_page); | |
3137 | EXPORT_SYMBOL(cont_prepare_write); | |
3138 | EXPORT_SYMBOL(end_buffer_async_write); | |
3139 | EXPORT_SYMBOL(end_buffer_read_sync); | |
3140 | EXPORT_SYMBOL(end_buffer_write_sync); | |
3141 | EXPORT_SYMBOL(file_fsync); | |
3142 | EXPORT_SYMBOL(fsync_bdev); | |
3143 | EXPORT_SYMBOL(generic_block_bmap); | |
3144 | EXPORT_SYMBOL(generic_commit_write); | |
3145 | EXPORT_SYMBOL(generic_cont_expand); | |
3146 | EXPORT_SYMBOL(init_buffer); | |
3147 | EXPORT_SYMBOL(invalidate_bdev); | |
3148 | EXPORT_SYMBOL(ll_rw_block); | |
3149 | EXPORT_SYMBOL(mark_buffer_dirty); | |
3150 | EXPORT_SYMBOL(submit_bh); | |
3151 | EXPORT_SYMBOL(sync_dirty_buffer); | |
3152 | EXPORT_SYMBOL(unlock_buffer); |