Commit | Line | Data |
---|---|---|
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 | ||
1da177e4 LT |
21 | #include <linux/kernel.h> |
22 | #include <linux/syscalls.h> | |
23 | #include <linux/fs.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/percpu.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/smp_lock.h> | |
16f7e0fe | 28 | #include <linux/capability.h> |
1da177e4 LT |
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> | |
fb1c8f93 | 43 | #include <linux/bit_spinlock.h> |
1da177e4 LT |
44 | |
45 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); | |
46 | static void invalidate_bh_lrus(void); | |
47 | ||
48 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) | |
49 | ||
50 | inline void | |
51 | init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) | |
52 | { | |
53 | bh->b_end_io = handler; | |
54 | bh->b_private = private; | |
55 | } | |
56 | ||
57 | static int sync_buffer(void *word) | |
58 | { | |
59 | struct block_device *bd; | |
60 | struct buffer_head *bh | |
61 | = container_of(word, struct buffer_head, b_state); | |
62 | ||
63 | smp_mb(); | |
64 | bd = bh->b_bdev; | |
65 | if (bd) | |
66 | blk_run_address_space(bd->bd_inode->i_mapping); | |
67 | io_schedule(); | |
68 | return 0; | |
69 | } | |
70 | ||
71 | void fastcall __lock_buffer(struct buffer_head *bh) | |
72 | { | |
73 | wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, | |
74 | TASK_UNINTERRUPTIBLE); | |
75 | } | |
76 | EXPORT_SYMBOL(__lock_buffer); | |
77 | ||
78 | void fastcall unlock_buffer(struct buffer_head *bh) | |
79 | { | |
80 | clear_buffer_locked(bh); | |
81 | smp_mb__after_clear_bit(); | |
82 | wake_up_bit(&bh->b_state, BH_Lock); | |
83 | } | |
84 | ||
85 | /* | |
86 | * Block until a buffer comes unlocked. This doesn't stop it | |
87 | * from becoming locked again - you have to lock it yourself | |
88 | * if you want to preserve its state. | |
89 | */ | |
90 | void __wait_on_buffer(struct buffer_head * bh) | |
91 | { | |
92 | wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); | |
93 | } | |
94 | ||
95 | static void | |
96 | __clear_page_buffers(struct page *page) | |
97 | { | |
98 | ClearPagePrivate(page); | |
4c21e2f2 | 99 | set_page_private(page, 0); |
1da177e4 LT |
100 | page_cache_release(page); |
101 | } | |
102 | ||
103 | static void buffer_io_error(struct buffer_head *bh) | |
104 | { | |
105 | char b[BDEVNAME_SIZE]; | |
106 | ||
107 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", | |
108 | bdevname(bh->b_bdev, b), | |
109 | (unsigned long long)bh->b_blocknr); | |
110 | } | |
111 | ||
112 | /* | |
113 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
114 | * unlock the buffer. This is what ll_rw_block uses too. | |
115 | */ | |
116 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
117 | { | |
118 | if (uptodate) { | |
119 | set_buffer_uptodate(bh); | |
120 | } else { | |
121 | /* This happens, due to failed READA attempts. */ | |
122 | clear_buffer_uptodate(bh); | |
123 | } | |
124 | unlock_buffer(bh); | |
125 | put_bh(bh); | |
126 | } | |
127 | ||
128 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
129 | { | |
130 | char b[BDEVNAME_SIZE]; | |
131 | ||
132 | if (uptodate) { | |
133 | set_buffer_uptodate(bh); | |
134 | } else { | |
135 | if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { | |
136 | buffer_io_error(bh); | |
137 | printk(KERN_WARNING "lost page write due to " | |
138 | "I/O error on %s\n", | |
139 | bdevname(bh->b_bdev, b)); | |
140 | } | |
141 | set_buffer_write_io_error(bh); | |
142 | clear_buffer_uptodate(bh); | |
143 | } | |
144 | unlock_buffer(bh); | |
145 | put_bh(bh); | |
146 | } | |
147 | ||
148 | /* | |
149 | * Write out and wait upon all the dirty data associated with a block | |
150 | * device via its mapping. Does not take the superblock lock. | |
151 | */ | |
152 | int sync_blockdev(struct block_device *bdev) | |
153 | { | |
154 | int ret = 0; | |
155 | ||
28fd1298 OH |
156 | if (bdev) |
157 | ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); | |
1da177e4 LT |
158 | return ret; |
159 | } | |
160 | EXPORT_SYMBOL(sync_blockdev); | |
161 | ||
1da177e4 LT |
162 | /* |
163 | * Write out and wait upon all dirty data associated with this | |
164 | * device. Filesystem data as well as the underlying block | |
165 | * device. Takes the superblock lock. | |
166 | */ | |
167 | int fsync_bdev(struct block_device *bdev) | |
168 | { | |
169 | struct super_block *sb = get_super(bdev); | |
170 | if (sb) { | |
171 | int res = fsync_super(sb); | |
172 | drop_super(sb); | |
173 | return res; | |
174 | } | |
175 | return sync_blockdev(bdev); | |
176 | } | |
177 | ||
178 | /** | |
179 | * freeze_bdev -- lock a filesystem and force it into a consistent state | |
180 | * @bdev: blockdevice to lock | |
181 | * | |
c039e313 | 182 | * This takes the block device bd_mount_mutex to make sure no new mounts |
1da177e4 LT |
183 | * happen on bdev until thaw_bdev() is called. |
184 | * If a superblock is found on this device, we take the s_umount semaphore | |
185 | * on it to make sure nobody unmounts until the snapshot creation is done. | |
186 | */ | |
187 | struct super_block *freeze_bdev(struct block_device *bdev) | |
188 | { | |
189 | struct super_block *sb; | |
190 | ||
c039e313 | 191 | mutex_lock(&bdev->bd_mount_mutex); |
1da177e4 LT |
192 | sb = get_super(bdev); |
193 | if (sb && !(sb->s_flags & MS_RDONLY)) { | |
194 | sb->s_frozen = SB_FREEZE_WRITE; | |
d59dd462 | 195 | smp_wmb(); |
1da177e4 | 196 | |
d25b9a1f | 197 | __fsync_super(sb); |
1da177e4 LT |
198 | |
199 | sb->s_frozen = SB_FREEZE_TRANS; | |
d59dd462 | 200 | smp_wmb(); |
1da177e4 LT |
201 | |
202 | sync_blockdev(sb->s_bdev); | |
203 | ||
204 | if (sb->s_op->write_super_lockfs) | |
205 | sb->s_op->write_super_lockfs(sb); | |
206 | } | |
207 | ||
208 | sync_blockdev(bdev); | |
209 | return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ | |
210 | } | |
211 | EXPORT_SYMBOL(freeze_bdev); | |
212 | ||
213 | /** | |
214 | * thaw_bdev -- unlock filesystem | |
215 | * @bdev: blockdevice to unlock | |
216 | * @sb: associated superblock | |
217 | * | |
218 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). | |
219 | */ | |
220 | void thaw_bdev(struct block_device *bdev, struct super_block *sb) | |
221 | { | |
222 | if (sb) { | |
223 | BUG_ON(sb->s_bdev != bdev); | |
224 | ||
225 | if (sb->s_op->unlockfs) | |
226 | sb->s_op->unlockfs(sb); | |
227 | sb->s_frozen = SB_UNFROZEN; | |
d59dd462 | 228 | smp_wmb(); |
1da177e4 LT |
229 | wake_up(&sb->s_wait_unfrozen); |
230 | drop_super(sb); | |
231 | } | |
232 | ||
c039e313 | 233 | mutex_unlock(&bdev->bd_mount_mutex); |
1da177e4 LT |
234 | } |
235 | EXPORT_SYMBOL(thaw_bdev); | |
236 | ||
1da177e4 LT |
237 | /* |
238 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
239 | * But it's the page lock which protects the buffers. To get around this, | |
240 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
241 | * private_lock. | |
242 | * | |
243 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
244 | * may be quite high. This code could TryLock the page, and if that | |
245 | * succeeds, there is no need to take private_lock. (But if | |
246 | * private_lock is contended then so is mapping->tree_lock). | |
247 | */ | |
248 | static struct buffer_head * | |
385fd4c5 | 249 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
250 | { |
251 | struct inode *bd_inode = bdev->bd_inode; | |
252 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
253 | struct buffer_head *ret = NULL; | |
254 | pgoff_t index; | |
255 | struct buffer_head *bh; | |
256 | struct buffer_head *head; | |
257 | struct page *page; | |
258 | int all_mapped = 1; | |
259 | ||
260 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
261 | page = find_get_page(bd_mapping, index); | |
262 | if (!page) | |
263 | goto out; | |
264 | ||
265 | spin_lock(&bd_mapping->private_lock); | |
266 | if (!page_has_buffers(page)) | |
267 | goto out_unlock; | |
268 | head = page_buffers(page); | |
269 | bh = head; | |
270 | do { | |
271 | if (bh->b_blocknr == block) { | |
272 | ret = bh; | |
273 | get_bh(bh); | |
274 | goto out_unlock; | |
275 | } | |
276 | if (!buffer_mapped(bh)) | |
277 | all_mapped = 0; | |
278 | bh = bh->b_this_page; | |
279 | } while (bh != head); | |
280 | ||
281 | /* we might be here because some of the buffers on this page are | |
282 | * not mapped. This is due to various races between | |
283 | * file io on the block device and getblk. It gets dealt with | |
284 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
285 | */ | |
286 | if (all_mapped) { | |
287 | printk("__find_get_block_slow() failed. " | |
288 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
289 | (unsigned long long)block, |
290 | (unsigned long long)bh->b_blocknr); | |
291 | printk("b_state=0x%08lx, b_size=%zu\n", | |
292 | bh->b_state, bh->b_size); | |
1da177e4 LT |
293 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
294 | } | |
295 | out_unlock: | |
296 | spin_unlock(&bd_mapping->private_lock); | |
297 | page_cache_release(page); | |
298 | out: | |
299 | return ret; | |
300 | } | |
301 | ||
302 | /* If invalidate_buffers() will trash dirty buffers, it means some kind | |
303 | of fs corruption is going on. Trashing dirty data always imply losing | |
304 | information that was supposed to be just stored on the physical layer | |
305 | by the user. | |
306 | ||
307 | Thus invalidate_buffers in general usage is not allwowed to trash | |
308 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to | |
309 | be preserved. These buffers are simply skipped. | |
310 | ||
311 | We also skip buffers which are still in use. For example this can | |
312 | happen if a userspace program is reading the block device. | |
313 | ||
314 | NOTE: In the case where the user removed a removable-media-disk even if | |
315 | there's still dirty data not synced on disk (due a bug in the device driver | |
316 | or due an error of the user), by not destroying the dirty buffers we could | |
317 | generate corruption also on the next media inserted, thus a parameter is | |
318 | necessary to handle this case in the most safe way possible (trying | |
319 | to not corrupt also the new disk inserted with the data belonging to | |
320 | the old now corrupted disk). Also for the ramdisk the natural thing | |
321 | to do in order to release the ramdisk memory is to destroy dirty buffers. | |
322 | ||
323 | These are two special cases. Normal usage imply the device driver | |
324 | to issue a sync on the device (without waiting I/O completion) and | |
325 | then an invalidate_buffers call that doesn't trash dirty buffers. | |
326 | ||
327 | For handling cache coherency with the blkdev pagecache the 'update' case | |
328 | is been introduced. It is needed to re-read from disk any pinned | |
329 | buffer. NOTE: re-reading from disk is destructive so we can do it only | |
330 | when we assume nobody is changing the buffercache under our I/O and when | |
331 | we think the disk contains more recent information than the buffercache. | |
332 | The update == 1 pass marks the buffers we need to update, the update == 2 | |
333 | pass does the actual I/O. */ | |
334 | void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) | |
335 | { | |
0e1dfc66 AM |
336 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
337 | ||
338 | if (mapping->nrpages == 0) | |
339 | return; | |
340 | ||
1da177e4 LT |
341 | invalidate_bh_lrus(); |
342 | /* | |
343 | * FIXME: what about destroy_dirty_buffers? | |
344 | * We really want to use invalidate_inode_pages2() for | |
345 | * that, but not until that's cleaned up. | |
346 | */ | |
0e1dfc66 | 347 | invalidate_inode_pages(mapping); |
1da177e4 LT |
348 | } |
349 | ||
350 | /* | |
351 | * Kick pdflush then try to free up some ZONE_NORMAL memory. | |
352 | */ | |
353 | static void free_more_memory(void) | |
354 | { | |
355 | struct zone **zones; | |
356 | pg_data_t *pgdat; | |
357 | ||
687a21ce | 358 | wakeup_pdflush(1024); |
1da177e4 LT |
359 | yield(); |
360 | ||
ec936fc5 | 361 | for_each_online_pgdat(pgdat) { |
af4ca457 | 362 | zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones; |
1da177e4 | 363 | if (*zones) |
1ad539b2 | 364 | try_to_free_pages(zones, GFP_NOFS); |
1da177e4 LT |
365 | } |
366 | } | |
367 | ||
368 | /* | |
369 | * I/O completion handler for block_read_full_page() - pages | |
370 | * which come unlocked at the end of I/O. | |
371 | */ | |
372 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
373 | { | |
1da177e4 | 374 | unsigned long flags; |
a3972203 | 375 | struct buffer_head *first; |
1da177e4 LT |
376 | struct buffer_head *tmp; |
377 | struct page *page; | |
378 | int page_uptodate = 1; | |
379 | ||
380 | BUG_ON(!buffer_async_read(bh)); | |
381 | ||
382 | page = bh->b_page; | |
383 | if (uptodate) { | |
384 | set_buffer_uptodate(bh); | |
385 | } else { | |
386 | clear_buffer_uptodate(bh); | |
387 | if (printk_ratelimit()) | |
388 | buffer_io_error(bh); | |
389 | SetPageError(page); | |
390 | } | |
391 | ||
392 | /* | |
393 | * Be _very_ careful from here on. Bad things can happen if | |
394 | * two buffer heads end IO at almost the same time and both | |
395 | * decide that the page is now completely done. | |
396 | */ | |
a3972203 NP |
397 | first = page_buffers(page); |
398 | local_irq_save(flags); | |
399 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
400 | clear_buffer_async_read(bh); |
401 | unlock_buffer(bh); | |
402 | tmp = bh; | |
403 | do { | |
404 | if (!buffer_uptodate(tmp)) | |
405 | page_uptodate = 0; | |
406 | if (buffer_async_read(tmp)) { | |
407 | BUG_ON(!buffer_locked(tmp)); | |
408 | goto still_busy; | |
409 | } | |
410 | tmp = tmp->b_this_page; | |
411 | } while (tmp != bh); | |
a3972203 NP |
412 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
413 | local_irq_restore(flags); | |
1da177e4 LT |
414 | |
415 | /* | |
416 | * If none of the buffers had errors and they are all | |
417 | * uptodate then we can set the page uptodate. | |
418 | */ | |
419 | if (page_uptodate && !PageError(page)) | |
420 | SetPageUptodate(page); | |
421 | unlock_page(page); | |
422 | return; | |
423 | ||
424 | still_busy: | |
a3972203 NP |
425 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
426 | local_irq_restore(flags); | |
1da177e4 LT |
427 | return; |
428 | } | |
429 | ||
430 | /* | |
431 | * Completion handler for block_write_full_page() - pages which are unlocked | |
432 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
433 | */ | |
b6cd0b77 | 434 | static void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
435 | { |
436 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 437 | unsigned long flags; |
a3972203 | 438 | struct buffer_head *first; |
1da177e4 LT |
439 | struct buffer_head *tmp; |
440 | struct page *page; | |
441 | ||
442 | BUG_ON(!buffer_async_write(bh)); | |
443 | ||
444 | page = bh->b_page; | |
445 | if (uptodate) { | |
446 | set_buffer_uptodate(bh); | |
447 | } else { | |
448 | if (printk_ratelimit()) { | |
449 | buffer_io_error(bh); | |
450 | printk(KERN_WARNING "lost page write due to " | |
451 | "I/O error on %s\n", | |
452 | bdevname(bh->b_bdev, b)); | |
453 | } | |
454 | set_bit(AS_EIO, &page->mapping->flags); | |
455 | clear_buffer_uptodate(bh); | |
456 | SetPageError(page); | |
457 | } | |
458 | ||
a3972203 NP |
459 | first = page_buffers(page); |
460 | local_irq_save(flags); | |
461 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
462 | ||
1da177e4 LT |
463 | clear_buffer_async_write(bh); |
464 | unlock_buffer(bh); | |
465 | tmp = bh->b_this_page; | |
466 | while (tmp != bh) { | |
467 | if (buffer_async_write(tmp)) { | |
468 | BUG_ON(!buffer_locked(tmp)); | |
469 | goto still_busy; | |
470 | } | |
471 | tmp = tmp->b_this_page; | |
472 | } | |
a3972203 NP |
473 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
474 | local_irq_restore(flags); | |
1da177e4 LT |
475 | end_page_writeback(page); |
476 | return; | |
477 | ||
478 | still_busy: | |
a3972203 NP |
479 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
480 | local_irq_restore(flags); | |
1da177e4 LT |
481 | return; |
482 | } | |
483 | ||
484 | /* | |
485 | * If a page's buffers are under async readin (end_buffer_async_read | |
486 | * completion) then there is a possibility that another thread of | |
487 | * control could lock one of the buffers after it has completed | |
488 | * but while some of the other buffers have not completed. This | |
489 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
490 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
491 | * that this buffer is not under async I/O. | |
492 | * | |
493 | * The page comes unlocked when it has no locked buffer_async buffers | |
494 | * left. | |
495 | * | |
496 | * PageLocked prevents anyone starting new async I/O reads any of | |
497 | * the buffers. | |
498 | * | |
499 | * PageWriteback is used to prevent simultaneous writeout of the same | |
500 | * page. | |
501 | * | |
502 | * PageLocked prevents anyone from starting writeback of a page which is | |
503 | * under read I/O (PageWriteback is only ever set against a locked page). | |
504 | */ | |
505 | static void mark_buffer_async_read(struct buffer_head *bh) | |
506 | { | |
507 | bh->b_end_io = end_buffer_async_read; | |
508 | set_buffer_async_read(bh); | |
509 | } | |
510 | ||
511 | void mark_buffer_async_write(struct buffer_head *bh) | |
512 | { | |
513 | bh->b_end_io = end_buffer_async_write; | |
514 | set_buffer_async_write(bh); | |
515 | } | |
516 | EXPORT_SYMBOL(mark_buffer_async_write); | |
517 | ||
518 | ||
519 | /* | |
520 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
521 | * fsync functions. A common requirement for buffer-based filesystems is | |
522 | * that certain data from the backing blockdev needs to be written out for | |
523 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
524 | * written back and waited upon before fsync() returns. | |
525 | * | |
526 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
527 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
528 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
529 | * | |
530 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
531 | * from their controlling inode's queue when they are being freed. But | |
532 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
533 | * at the time, not against the S_ISREG file which depends on those buffers. | |
534 | * So the locking for private_list is via the private_lock in the address_space | |
535 | * which backs the buffers. Which is different from the address_space | |
536 | * against which the buffers are listed. So for a particular address_space, | |
537 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
538 | * mapping->private_list will always be protected by the backing blockdev's | |
539 | * ->private_lock. | |
540 | * | |
541 | * Which introduces a requirement: all buffers on an address_space's | |
542 | * ->private_list must be from the same address_space: the blockdev's. | |
543 | * | |
544 | * address_spaces which do not place buffers at ->private_list via these | |
545 | * utility functions are free to use private_lock and private_list for | |
546 | * whatever they want. The only requirement is that list_empty(private_list) | |
547 | * be true at clear_inode() time. | |
548 | * | |
549 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
550 | * filesystems should do that. invalidate_inode_buffers() should just go | |
551 | * BUG_ON(!list_empty). | |
552 | * | |
553 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
554 | * take an address_space, not an inode. And it should be called | |
555 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
556 | * queued up. | |
557 | * | |
558 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
559 | * list if it is already on a list. Because if the buffer is on a list, | |
560 | * it *must* already be on the right one. If not, the filesystem is being | |
561 | * silly. This will save a ton of locking. But first we have to ensure | |
562 | * that buffers are taken *off* the old inode's list when they are freed | |
563 | * (presumably in truncate). That requires careful auditing of all | |
564 | * filesystems (do it inside bforget()). It could also be done by bringing | |
565 | * b_inode back. | |
566 | */ | |
567 | ||
568 | /* | |
569 | * The buffer's backing address_space's private_lock must be held | |
570 | */ | |
571 | static inline void __remove_assoc_queue(struct buffer_head *bh) | |
572 | { | |
573 | list_del_init(&bh->b_assoc_buffers); | |
574 | } | |
575 | ||
576 | int inode_has_buffers(struct inode *inode) | |
577 | { | |
578 | return !list_empty(&inode->i_data.private_list); | |
579 | } | |
580 | ||
581 | /* | |
582 | * osync is designed to support O_SYNC io. It waits synchronously for | |
583 | * all already-submitted IO to complete, but does not queue any new | |
584 | * writes to the disk. | |
585 | * | |
586 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
587 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
588 | * completion. Any other dirty buffers which are not yet queued for | |
589 | * write will not be flushed to disk by the osync. | |
590 | */ | |
591 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
592 | { | |
593 | struct buffer_head *bh; | |
594 | struct list_head *p; | |
595 | int err = 0; | |
596 | ||
597 | spin_lock(lock); | |
598 | repeat: | |
599 | list_for_each_prev(p, list) { | |
600 | bh = BH_ENTRY(p); | |
601 | if (buffer_locked(bh)) { | |
602 | get_bh(bh); | |
603 | spin_unlock(lock); | |
604 | wait_on_buffer(bh); | |
605 | if (!buffer_uptodate(bh)) | |
606 | err = -EIO; | |
607 | brelse(bh); | |
608 | spin_lock(lock); | |
609 | goto repeat; | |
610 | } | |
611 | } | |
612 | spin_unlock(lock); | |
613 | return err; | |
614 | } | |
615 | ||
616 | /** | |
617 | * sync_mapping_buffers - write out and wait upon a mapping's "associated" | |
618 | * buffers | |
67be2dd1 | 619 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
620 | * |
621 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
622 | * that I/O. | |
623 | * | |
67be2dd1 MW |
624 | * Basically, this is a convenience function for fsync(). |
625 | * @mapping is a file or directory which needs those buffers to be written for | |
626 | * a successful fsync(). | |
1da177e4 LT |
627 | */ |
628 | int sync_mapping_buffers(struct address_space *mapping) | |
629 | { | |
630 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
631 | ||
632 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
633 | return 0; | |
634 | ||
635 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
636 | &mapping->private_list); | |
637 | } | |
638 | EXPORT_SYMBOL(sync_mapping_buffers); | |
639 | ||
640 | /* | |
641 | * Called when we've recently written block `bblock', and it is known that | |
642 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
643 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
644 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
645 | */ | |
646 | void write_boundary_block(struct block_device *bdev, | |
647 | sector_t bblock, unsigned blocksize) | |
648 | { | |
649 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
650 | if (bh) { | |
651 | if (buffer_dirty(bh)) | |
652 | ll_rw_block(WRITE, 1, &bh); | |
653 | put_bh(bh); | |
654 | } | |
655 | } | |
656 | ||
657 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
658 | { | |
659 | struct address_space *mapping = inode->i_mapping; | |
660 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
661 | ||
662 | mark_buffer_dirty(bh); | |
663 | if (!mapping->assoc_mapping) { | |
664 | mapping->assoc_mapping = buffer_mapping; | |
665 | } else { | |
e827f923 | 666 | BUG_ON(mapping->assoc_mapping != buffer_mapping); |
1da177e4 LT |
667 | } |
668 | if (list_empty(&bh->b_assoc_buffers)) { | |
669 | spin_lock(&buffer_mapping->private_lock); | |
670 | list_move_tail(&bh->b_assoc_buffers, | |
671 | &mapping->private_list); | |
672 | spin_unlock(&buffer_mapping->private_lock); | |
673 | } | |
674 | } | |
675 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
676 | ||
677 | /* | |
678 | * Add a page to the dirty page list. | |
679 | * | |
680 | * It is a sad fact of life that this function is called from several places | |
681 | * deeply under spinlocking. It may not sleep. | |
682 | * | |
683 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
684 | * dirty-state coherency between the page and the buffers. It the page does | |
685 | * not have buffers then when they are later attached they will all be set | |
686 | * dirty. | |
687 | * | |
688 | * The buffers are dirtied before the page is dirtied. There's a small race | |
689 | * window in which a writepage caller may see the page cleanness but not the | |
690 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
691 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
692 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
693 | * page on the dirty page list. | |
694 | * | |
695 | * We use private_lock to lock against try_to_free_buffers while using the | |
696 | * page's buffer list. Also use this to protect against clean buffers being | |
697 | * added to the page after it was set dirty. | |
698 | * | |
699 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
700 | * address_space though. | |
701 | */ | |
702 | int __set_page_dirty_buffers(struct page *page) | |
703 | { | |
ebf7a227 NP |
704 | struct address_space * const mapping = page_mapping(page); |
705 | ||
706 | if (unlikely(!mapping)) | |
707 | return !TestSetPageDirty(page); | |
1da177e4 LT |
708 | |
709 | spin_lock(&mapping->private_lock); | |
710 | if (page_has_buffers(page)) { | |
711 | struct buffer_head *head = page_buffers(page); | |
712 | struct buffer_head *bh = head; | |
713 | ||
714 | do { | |
715 | set_buffer_dirty(bh); | |
716 | bh = bh->b_this_page; | |
717 | } while (bh != head); | |
718 | } | |
719 | spin_unlock(&mapping->private_lock); | |
720 | ||
721 | if (!TestSetPageDirty(page)) { | |
722 | write_lock_irq(&mapping->tree_lock); | |
723 | if (page->mapping) { /* Race with truncate? */ | |
724 | if (mapping_cap_account_dirty(mapping)) | |
b1e7a8fd | 725 | __inc_zone_page_state(page, NR_FILE_DIRTY); |
1da177e4 LT |
726 | radix_tree_tag_set(&mapping->page_tree, |
727 | page_index(page), | |
728 | PAGECACHE_TAG_DIRTY); | |
729 | } | |
730 | write_unlock_irq(&mapping->tree_lock); | |
731 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
4741c9fd | 732 | return 1; |
1da177e4 | 733 | } |
1da177e4 LT |
734 | return 0; |
735 | } | |
736 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
737 | ||
738 | /* | |
739 | * Write out and wait upon a list of buffers. | |
740 | * | |
741 | * We have conflicting pressures: we want to make sure that all | |
742 | * initially dirty buffers get waited on, but that any subsequently | |
743 | * dirtied buffers don't. After all, we don't want fsync to last | |
744 | * forever if somebody is actively writing to the file. | |
745 | * | |
746 | * Do this in two main stages: first we copy dirty buffers to a | |
747 | * temporary inode list, queueing the writes as we go. Then we clean | |
748 | * up, waiting for those writes to complete. | |
749 | * | |
750 | * During this second stage, any subsequent updates to the file may end | |
751 | * up refiling the buffer on the original inode's dirty list again, so | |
752 | * there is a chance we will end up with a buffer queued for write but | |
753 | * not yet completed on that list. So, as a final cleanup we go through | |
754 | * the osync code to catch these locked, dirty buffers without requeuing | |
755 | * any newly dirty buffers for write. | |
756 | */ | |
757 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
758 | { | |
759 | struct buffer_head *bh; | |
760 | struct list_head tmp; | |
761 | int err = 0, err2; | |
762 | ||
763 | INIT_LIST_HEAD(&tmp); | |
764 | ||
765 | spin_lock(lock); | |
766 | while (!list_empty(list)) { | |
767 | bh = BH_ENTRY(list->next); | |
768 | list_del_init(&bh->b_assoc_buffers); | |
769 | if (buffer_dirty(bh) || buffer_locked(bh)) { | |
770 | list_add(&bh->b_assoc_buffers, &tmp); | |
771 | if (buffer_dirty(bh)) { | |
772 | get_bh(bh); | |
773 | spin_unlock(lock); | |
774 | /* | |
775 | * Ensure any pending I/O completes so that | |
776 | * ll_rw_block() actually writes the current | |
777 | * contents - it is a noop if I/O is still in | |
778 | * flight on potentially older contents. | |
779 | */ | |
a7662236 | 780 | ll_rw_block(SWRITE, 1, &bh); |
1da177e4 LT |
781 | brelse(bh); |
782 | spin_lock(lock); | |
783 | } | |
784 | } | |
785 | } | |
786 | ||
787 | while (!list_empty(&tmp)) { | |
788 | bh = BH_ENTRY(tmp.prev); | |
789 | __remove_assoc_queue(bh); | |
790 | get_bh(bh); | |
791 | spin_unlock(lock); | |
792 | wait_on_buffer(bh); | |
793 | if (!buffer_uptodate(bh)) | |
794 | err = -EIO; | |
795 | brelse(bh); | |
796 | spin_lock(lock); | |
797 | } | |
798 | ||
799 | spin_unlock(lock); | |
800 | err2 = osync_buffers_list(lock, list); | |
801 | if (err) | |
802 | return err; | |
803 | else | |
804 | return err2; | |
805 | } | |
806 | ||
807 | /* | |
808 | * Invalidate any and all dirty buffers on a given inode. We are | |
809 | * probably unmounting the fs, but that doesn't mean we have already | |
810 | * done a sync(). Just drop the buffers from the inode list. | |
811 | * | |
812 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
813 | * assumes that all the buffers are against the blockdev. Not true | |
814 | * for reiserfs. | |
815 | */ | |
816 | void invalidate_inode_buffers(struct inode *inode) | |
817 | { | |
818 | if (inode_has_buffers(inode)) { | |
819 | struct address_space *mapping = &inode->i_data; | |
820 | struct list_head *list = &mapping->private_list; | |
821 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
822 | ||
823 | spin_lock(&buffer_mapping->private_lock); | |
824 | while (!list_empty(list)) | |
825 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
826 | spin_unlock(&buffer_mapping->private_lock); | |
827 | } | |
828 | } | |
829 | ||
830 | /* | |
831 | * Remove any clean buffers from the inode's buffer list. This is called | |
832 | * when we're trying to free the inode itself. Those buffers can pin it. | |
833 | * | |
834 | * Returns true if all buffers were removed. | |
835 | */ | |
836 | int remove_inode_buffers(struct inode *inode) | |
837 | { | |
838 | int ret = 1; | |
839 | ||
840 | if (inode_has_buffers(inode)) { | |
841 | struct address_space *mapping = &inode->i_data; | |
842 | struct list_head *list = &mapping->private_list; | |
843 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
844 | ||
845 | spin_lock(&buffer_mapping->private_lock); | |
846 | while (!list_empty(list)) { | |
847 | struct buffer_head *bh = BH_ENTRY(list->next); | |
848 | if (buffer_dirty(bh)) { | |
849 | ret = 0; | |
850 | break; | |
851 | } | |
852 | __remove_assoc_queue(bh); | |
853 | } | |
854 | spin_unlock(&buffer_mapping->private_lock); | |
855 | } | |
856 | return ret; | |
857 | } | |
858 | ||
859 | /* | |
860 | * Create the appropriate buffers when given a page for data area and | |
861 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
862 | * follow the buffers created. Return NULL if unable to create more | |
863 | * buffers. | |
864 | * | |
865 | * The retry flag is used to differentiate async IO (paging, swapping) | |
866 | * which may not fail from ordinary buffer allocations. | |
867 | */ | |
868 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
869 | int retry) | |
870 | { | |
871 | struct buffer_head *bh, *head; | |
872 | long offset; | |
873 | ||
874 | try_again: | |
875 | head = NULL; | |
876 | offset = PAGE_SIZE; | |
877 | while ((offset -= size) >= 0) { | |
878 | bh = alloc_buffer_head(GFP_NOFS); | |
879 | if (!bh) | |
880 | goto no_grow; | |
881 | ||
882 | bh->b_bdev = NULL; | |
883 | bh->b_this_page = head; | |
884 | bh->b_blocknr = -1; | |
885 | head = bh; | |
886 | ||
887 | bh->b_state = 0; | |
888 | atomic_set(&bh->b_count, 0); | |
fc5cd582 | 889 | bh->b_private = NULL; |
1da177e4 LT |
890 | bh->b_size = size; |
891 | ||
892 | /* Link the buffer to its page */ | |
893 | set_bh_page(bh, page, offset); | |
894 | ||
01ffe339 | 895 | init_buffer(bh, NULL, NULL); |
1da177e4 LT |
896 | } |
897 | return head; | |
898 | /* | |
899 | * In case anything failed, we just free everything we got. | |
900 | */ | |
901 | no_grow: | |
902 | if (head) { | |
903 | do { | |
904 | bh = head; | |
905 | head = head->b_this_page; | |
906 | free_buffer_head(bh); | |
907 | } while (head); | |
908 | } | |
909 | ||
910 | /* | |
911 | * Return failure for non-async IO requests. Async IO requests | |
912 | * are not allowed to fail, so we have to wait until buffer heads | |
913 | * become available. But we don't want tasks sleeping with | |
914 | * partially complete buffers, so all were released above. | |
915 | */ | |
916 | if (!retry) | |
917 | return NULL; | |
918 | ||
919 | /* We're _really_ low on memory. Now we just | |
920 | * wait for old buffer heads to become free due to | |
921 | * finishing IO. Since this is an async request and | |
922 | * the reserve list is empty, we're sure there are | |
923 | * async buffer heads in use. | |
924 | */ | |
925 | free_more_memory(); | |
926 | goto try_again; | |
927 | } | |
928 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
929 | ||
930 | static inline void | |
931 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
932 | { | |
933 | struct buffer_head *bh, *tail; | |
934 | ||
935 | bh = head; | |
936 | do { | |
937 | tail = bh; | |
938 | bh = bh->b_this_page; | |
939 | } while (bh); | |
940 | tail->b_this_page = head; | |
941 | attach_page_buffers(page, head); | |
942 | } | |
943 | ||
944 | /* | |
945 | * Initialise the state of a blockdev page's buffers. | |
946 | */ | |
947 | static void | |
948 | init_page_buffers(struct page *page, struct block_device *bdev, | |
949 | sector_t block, int size) | |
950 | { | |
951 | struct buffer_head *head = page_buffers(page); | |
952 | struct buffer_head *bh = head; | |
953 | int uptodate = PageUptodate(page); | |
954 | ||
955 | do { | |
956 | if (!buffer_mapped(bh)) { | |
957 | init_buffer(bh, NULL, NULL); | |
958 | bh->b_bdev = bdev; | |
959 | bh->b_blocknr = block; | |
960 | if (uptodate) | |
961 | set_buffer_uptodate(bh); | |
962 | set_buffer_mapped(bh); | |
963 | } | |
964 | block++; | |
965 | bh = bh->b_this_page; | |
966 | } while (bh != head); | |
967 | } | |
968 | ||
969 | /* | |
970 | * Create the page-cache page that contains the requested block. | |
971 | * | |
972 | * This is user purely for blockdev mappings. | |
973 | */ | |
974 | static struct page * | |
975 | grow_dev_page(struct block_device *bdev, sector_t block, | |
976 | pgoff_t index, int size) | |
977 | { | |
978 | struct inode *inode = bdev->bd_inode; | |
979 | struct page *page; | |
980 | struct buffer_head *bh; | |
981 | ||
982 | page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); | |
983 | if (!page) | |
984 | return NULL; | |
985 | ||
e827f923 | 986 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
987 | |
988 | if (page_has_buffers(page)) { | |
989 | bh = page_buffers(page); | |
990 | if (bh->b_size == size) { | |
991 | init_page_buffers(page, bdev, block, size); | |
992 | return page; | |
993 | } | |
994 | if (!try_to_free_buffers(page)) | |
995 | goto failed; | |
996 | } | |
997 | ||
998 | /* | |
999 | * Allocate some buffers for this page | |
1000 | */ | |
1001 | bh = alloc_page_buffers(page, size, 0); | |
1002 | if (!bh) | |
1003 | goto failed; | |
1004 | ||
1005 | /* | |
1006 | * Link the page to the buffers and initialise them. Take the | |
1007 | * lock to be atomic wrt __find_get_block(), which does not | |
1008 | * run under the page lock. | |
1009 | */ | |
1010 | spin_lock(&inode->i_mapping->private_lock); | |
1011 | link_dev_buffers(page, bh); | |
1012 | init_page_buffers(page, bdev, block, size); | |
1013 | spin_unlock(&inode->i_mapping->private_lock); | |
1014 | return page; | |
1015 | ||
1016 | failed: | |
1017 | BUG(); | |
1018 | unlock_page(page); | |
1019 | page_cache_release(page); | |
1020 | return NULL; | |
1021 | } | |
1022 | ||
1023 | /* | |
1024 | * Create buffers for the specified block device block's page. If | |
1025 | * that page was dirty, the buffers are set dirty also. | |
1026 | * | |
1027 | * Except that's a bug. Attaching dirty buffers to a dirty | |
1028 | * blockdev's page can result in filesystem corruption, because | |
1029 | * some of those buffers may be aliases of filesystem data. | |
1030 | * grow_dev_page() will go BUG() if this happens. | |
1031 | */ | |
858119e1 | 1032 | static int |
1da177e4 LT |
1033 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1034 | { | |
1035 | struct page *page; | |
1036 | pgoff_t index; | |
1037 | int sizebits; | |
1038 | ||
1039 | sizebits = -1; | |
1040 | do { | |
1041 | sizebits++; | |
1042 | } while ((size << sizebits) < PAGE_SIZE); | |
1043 | ||
1044 | index = block >> sizebits; | |
1da177e4 | 1045 | |
e5657933 AM |
1046 | /* |
1047 | * Check for a block which wants to lie outside our maximum possible | |
1048 | * pagecache index. (this comparison is done using sector_t types). | |
1049 | */ | |
1050 | if (unlikely(index != block >> sizebits)) { | |
1051 | char b[BDEVNAME_SIZE]; | |
1052 | ||
1053 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1054 | "device %s\n", | |
1055 | __FUNCTION__, (unsigned long long)block, | |
1056 | bdevname(bdev, b)); | |
1057 | return -EIO; | |
1058 | } | |
1059 | block = index << sizebits; | |
1da177e4 LT |
1060 | /* Create a page with the proper size buffers.. */ |
1061 | page = grow_dev_page(bdev, block, index, size); | |
1062 | if (!page) | |
1063 | return 0; | |
1064 | unlock_page(page); | |
1065 | page_cache_release(page); | |
1066 | return 1; | |
1067 | } | |
1068 | ||
75c96f85 | 1069 | static struct buffer_head * |
1da177e4 LT |
1070 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1071 | { | |
1072 | /* Size must be multiple of hard sectorsize */ | |
1073 | if (unlikely(size & (bdev_hardsect_size(bdev)-1) || | |
1074 | (size < 512 || size > PAGE_SIZE))) { | |
1075 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1076 | size); | |
1077 | printk(KERN_ERR "hardsect size: %d\n", | |
1078 | bdev_hardsect_size(bdev)); | |
1079 | ||
1080 | dump_stack(); | |
1081 | return NULL; | |
1082 | } | |
1083 | ||
1084 | for (;;) { | |
1085 | struct buffer_head * bh; | |
e5657933 | 1086 | int ret; |
1da177e4 LT |
1087 | |
1088 | bh = __find_get_block(bdev, block, size); | |
1089 | if (bh) | |
1090 | return bh; | |
1091 | ||
e5657933 AM |
1092 | ret = grow_buffers(bdev, block, size); |
1093 | if (ret < 0) | |
1094 | return NULL; | |
1095 | if (ret == 0) | |
1da177e4 LT |
1096 | free_more_memory(); |
1097 | } | |
1098 | } | |
1099 | ||
1100 | /* | |
1101 | * The relationship between dirty buffers and dirty pages: | |
1102 | * | |
1103 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1104 | * the page is tagged dirty in its radix tree. | |
1105 | * | |
1106 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1107 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1108 | * merely a hint about the true dirty state. | |
1109 | * | |
1110 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1111 | * (if the page has buffers). | |
1112 | * | |
1113 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1114 | * buffers are not. | |
1115 | * | |
1116 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1117 | * individually become uptodate. But their backing page remains not | |
1118 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1119 | * block_read_full_page() against that page will discover all the uptodate | |
1120 | * buffers, will set the page uptodate and will perform no I/O. | |
1121 | */ | |
1122 | ||
1123 | /** | |
1124 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1125 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1126 | * |
1127 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1128 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1129 | * tree and then attach the address_space's inode to its superblock's dirty | |
1130 | * inode list. | |
1131 | * | |
1132 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
1133 | * mapping->tree_lock and the global inode_lock. | |
1134 | */ | |
1135 | void fastcall mark_buffer_dirty(struct buffer_head *bh) | |
1136 | { | |
1137 | if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) | |
1138 | __set_page_dirty_nobuffers(bh->b_page); | |
1139 | } | |
1140 | ||
1141 | /* | |
1142 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1143 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1144 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1145 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1146 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1147 | */ | |
1148 | void __brelse(struct buffer_head * buf) | |
1149 | { | |
1150 | if (atomic_read(&buf->b_count)) { | |
1151 | put_bh(buf); | |
1152 | return; | |
1153 | } | |
1154 | printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); | |
1155 | WARN_ON(1); | |
1156 | } | |
1157 | ||
1158 | /* | |
1159 | * bforget() is like brelse(), except it discards any | |
1160 | * potentially dirty data. | |
1161 | */ | |
1162 | void __bforget(struct buffer_head *bh) | |
1163 | { | |
1164 | clear_buffer_dirty(bh); | |
1165 | if (!list_empty(&bh->b_assoc_buffers)) { | |
1166 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
1167 | ||
1168 | spin_lock(&buffer_mapping->private_lock); | |
1169 | list_del_init(&bh->b_assoc_buffers); | |
1170 | spin_unlock(&buffer_mapping->private_lock); | |
1171 | } | |
1172 | __brelse(bh); | |
1173 | } | |
1174 | ||
1175 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1176 | { | |
1177 | lock_buffer(bh); | |
1178 | if (buffer_uptodate(bh)) { | |
1179 | unlock_buffer(bh); | |
1180 | return bh; | |
1181 | } else { | |
1182 | get_bh(bh); | |
1183 | bh->b_end_io = end_buffer_read_sync; | |
1184 | submit_bh(READ, bh); | |
1185 | wait_on_buffer(bh); | |
1186 | if (buffer_uptodate(bh)) | |
1187 | return bh; | |
1188 | } | |
1189 | brelse(bh); | |
1190 | return NULL; | |
1191 | } | |
1192 | ||
1193 | /* | |
1194 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1195 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1196 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1197 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1198 | * CPU's LRUs at the same time. | |
1199 | * | |
1200 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1201 | * sb_find_get_block(). | |
1202 | * | |
1203 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1204 | * a local interrupt disable for that. | |
1205 | */ | |
1206 | ||
1207 | #define BH_LRU_SIZE 8 | |
1208 | ||
1209 | struct bh_lru { | |
1210 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1211 | }; | |
1212 | ||
1213 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1214 | ||
1215 | #ifdef CONFIG_SMP | |
1216 | #define bh_lru_lock() local_irq_disable() | |
1217 | #define bh_lru_unlock() local_irq_enable() | |
1218 | #else | |
1219 | #define bh_lru_lock() preempt_disable() | |
1220 | #define bh_lru_unlock() preempt_enable() | |
1221 | #endif | |
1222 | ||
1223 | static inline void check_irqs_on(void) | |
1224 | { | |
1225 | #ifdef irqs_disabled | |
1226 | BUG_ON(irqs_disabled()); | |
1227 | #endif | |
1228 | } | |
1229 | ||
1230 | /* | |
1231 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1232 | */ | |
1233 | static void bh_lru_install(struct buffer_head *bh) | |
1234 | { | |
1235 | struct buffer_head *evictee = NULL; | |
1236 | struct bh_lru *lru; | |
1237 | ||
1238 | check_irqs_on(); | |
1239 | bh_lru_lock(); | |
1240 | lru = &__get_cpu_var(bh_lrus); | |
1241 | if (lru->bhs[0] != bh) { | |
1242 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1243 | int in; | |
1244 | int out = 0; | |
1245 | ||
1246 | get_bh(bh); | |
1247 | bhs[out++] = bh; | |
1248 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
1249 | struct buffer_head *bh2 = lru->bhs[in]; | |
1250 | ||
1251 | if (bh2 == bh) { | |
1252 | __brelse(bh2); | |
1253 | } else { | |
1254 | if (out >= BH_LRU_SIZE) { | |
1255 | BUG_ON(evictee != NULL); | |
1256 | evictee = bh2; | |
1257 | } else { | |
1258 | bhs[out++] = bh2; | |
1259 | } | |
1260 | } | |
1261 | } | |
1262 | while (out < BH_LRU_SIZE) | |
1263 | bhs[out++] = NULL; | |
1264 | memcpy(lru->bhs, bhs, sizeof(bhs)); | |
1265 | } | |
1266 | bh_lru_unlock(); | |
1267 | ||
1268 | if (evictee) | |
1269 | __brelse(evictee); | |
1270 | } | |
1271 | ||
1272 | /* | |
1273 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1274 | */ | |
858119e1 | 1275 | static struct buffer_head * |
1da177e4 LT |
1276 | lookup_bh_lru(struct block_device *bdev, sector_t block, int size) |
1277 | { | |
1278 | struct buffer_head *ret = NULL; | |
1279 | struct bh_lru *lru; | |
1280 | int i; | |
1281 | ||
1282 | check_irqs_on(); | |
1283 | bh_lru_lock(); | |
1284 | lru = &__get_cpu_var(bh_lrus); | |
1285 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1286 | struct buffer_head *bh = lru->bhs[i]; | |
1287 | ||
1288 | if (bh && bh->b_bdev == bdev && | |
1289 | bh->b_blocknr == block && bh->b_size == size) { | |
1290 | if (i) { | |
1291 | while (i) { | |
1292 | lru->bhs[i] = lru->bhs[i - 1]; | |
1293 | i--; | |
1294 | } | |
1295 | lru->bhs[0] = bh; | |
1296 | } | |
1297 | get_bh(bh); | |
1298 | ret = bh; | |
1299 | break; | |
1300 | } | |
1301 | } | |
1302 | bh_lru_unlock(); | |
1303 | return ret; | |
1304 | } | |
1305 | ||
1306 | /* | |
1307 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1308 | * it in the LRU and mark it as accessed. If it is not present then return | |
1309 | * NULL | |
1310 | */ | |
1311 | struct buffer_head * | |
1312 | __find_get_block(struct block_device *bdev, sector_t block, int size) | |
1313 | { | |
1314 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1315 | ||
1316 | if (bh == NULL) { | |
385fd4c5 | 1317 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1318 | if (bh) |
1319 | bh_lru_install(bh); | |
1320 | } | |
1321 | if (bh) | |
1322 | touch_buffer(bh); | |
1323 | return bh; | |
1324 | } | |
1325 | EXPORT_SYMBOL(__find_get_block); | |
1326 | ||
1327 | /* | |
1328 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1329 | * which corresponds to the passed block_device, block and size. The | |
1330 | * returned buffer has its reference count incremented. | |
1331 | * | |
1332 | * __getblk() cannot fail - it just keeps trying. If you pass it an | |
1333 | * illegal block number, __getblk() will happily return a buffer_head | |
1334 | * which represents the non-existent block. Very weird. | |
1335 | * | |
1336 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() | |
1337 | * attempt is failing. FIXME, perhaps? | |
1338 | */ | |
1339 | struct buffer_head * | |
1340 | __getblk(struct block_device *bdev, sector_t block, int size) | |
1341 | { | |
1342 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1343 | ||
1344 | might_sleep(); | |
1345 | if (bh == NULL) | |
1346 | bh = __getblk_slow(bdev, block, size); | |
1347 | return bh; | |
1348 | } | |
1349 | EXPORT_SYMBOL(__getblk); | |
1350 | ||
1351 | /* | |
1352 | * Do async read-ahead on a buffer.. | |
1353 | */ | |
1354 | void __breadahead(struct block_device *bdev, sector_t block, int size) | |
1355 | { | |
1356 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1357 | if (likely(bh)) { |
1358 | ll_rw_block(READA, 1, &bh); | |
1359 | brelse(bh); | |
1360 | } | |
1da177e4 LT |
1361 | } |
1362 | EXPORT_SYMBOL(__breadahead); | |
1363 | ||
1364 | /** | |
1365 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1366 | * @bdev: the block_device to read from |
1da177e4 LT |
1367 | * @block: number of block |
1368 | * @size: size (in bytes) to read | |
1369 | * | |
1370 | * Reads a specified block, and returns buffer head that contains it. | |
1371 | * It returns NULL if the block was unreadable. | |
1372 | */ | |
1373 | struct buffer_head * | |
1374 | __bread(struct block_device *bdev, sector_t block, int size) | |
1375 | { | |
1376 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1377 | ||
a3e713b5 | 1378 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1379 | bh = __bread_slow(bh); |
1380 | return bh; | |
1381 | } | |
1382 | EXPORT_SYMBOL(__bread); | |
1383 | ||
1384 | /* | |
1385 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1386 | * This doesn't race because it runs in each cpu either in irq | |
1387 | * or with preempt disabled. | |
1388 | */ | |
1389 | static void invalidate_bh_lru(void *arg) | |
1390 | { | |
1391 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1392 | int i; | |
1393 | ||
1394 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1395 | brelse(b->bhs[i]); | |
1396 | b->bhs[i] = NULL; | |
1397 | } | |
1398 | put_cpu_var(bh_lrus); | |
1399 | } | |
1400 | ||
1401 | static void invalidate_bh_lrus(void) | |
1402 | { | |
1403 | on_each_cpu(invalidate_bh_lru, NULL, 1, 1); | |
1404 | } | |
1405 | ||
1406 | void set_bh_page(struct buffer_head *bh, | |
1407 | struct page *page, unsigned long offset) | |
1408 | { | |
1409 | bh->b_page = page; | |
e827f923 | 1410 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1411 | if (PageHighMem(page)) |
1412 | /* | |
1413 | * This catches illegal uses and preserves the offset: | |
1414 | */ | |
1415 | bh->b_data = (char *)(0 + offset); | |
1416 | else | |
1417 | bh->b_data = page_address(page) + offset; | |
1418 | } | |
1419 | EXPORT_SYMBOL(set_bh_page); | |
1420 | ||
1421 | /* | |
1422 | * Called when truncating a buffer on a page completely. | |
1423 | */ | |
858119e1 | 1424 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1425 | { |
1426 | lock_buffer(bh); | |
1427 | clear_buffer_dirty(bh); | |
1428 | bh->b_bdev = NULL; | |
1429 | clear_buffer_mapped(bh); | |
1430 | clear_buffer_req(bh); | |
1431 | clear_buffer_new(bh); | |
1432 | clear_buffer_delay(bh); | |
1433 | unlock_buffer(bh); | |
1434 | } | |
1435 | ||
1da177e4 LT |
1436 | /** |
1437 | * block_invalidatepage - invalidate part of all of a buffer-backed page | |
1438 | * | |
1439 | * @page: the page which is affected | |
1440 | * @offset: the index of the truncation point | |
1441 | * | |
1442 | * block_invalidatepage() is called when all or part of the page has become | |
1443 | * invalidatedby a truncate operation. | |
1444 | * | |
1445 | * block_invalidatepage() does not have to release all buffers, but it must | |
1446 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1447 | * is underway against any of the blocks which are outside the truncation | |
1448 | * point. Because the caller is about to free (and possibly reuse) those | |
1449 | * blocks on-disk. | |
1450 | */ | |
2ff28e22 | 1451 | void block_invalidatepage(struct page *page, unsigned long offset) |
1da177e4 LT |
1452 | { |
1453 | struct buffer_head *head, *bh, *next; | |
1454 | unsigned int curr_off = 0; | |
1da177e4 LT |
1455 | |
1456 | BUG_ON(!PageLocked(page)); | |
1457 | if (!page_has_buffers(page)) | |
1458 | goto out; | |
1459 | ||
1460 | head = page_buffers(page); | |
1461 | bh = head; | |
1462 | do { | |
1463 | unsigned int next_off = curr_off + bh->b_size; | |
1464 | next = bh->b_this_page; | |
1465 | ||
1466 | /* | |
1467 | * is this block fully invalidated? | |
1468 | */ | |
1469 | if (offset <= curr_off) | |
1470 | discard_buffer(bh); | |
1471 | curr_off = next_off; | |
1472 | bh = next; | |
1473 | } while (bh != head); | |
1474 | ||
1475 | /* | |
1476 | * We release buffers only if the entire page is being invalidated. | |
1477 | * The get_block cached value has been unconditionally invalidated, | |
1478 | * so real IO is not possible anymore. | |
1479 | */ | |
1480 | if (offset == 0) | |
2ff28e22 | 1481 | try_to_release_page(page, 0); |
1da177e4 | 1482 | out: |
2ff28e22 | 1483 | return; |
1da177e4 LT |
1484 | } |
1485 | EXPORT_SYMBOL(block_invalidatepage); | |
1486 | ||
1487 | /* | |
1488 | * We attach and possibly dirty the buffers atomically wrt | |
1489 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1490 | * is already excluded via the page lock. | |
1491 | */ | |
1492 | void create_empty_buffers(struct page *page, | |
1493 | unsigned long blocksize, unsigned long b_state) | |
1494 | { | |
1495 | struct buffer_head *bh, *head, *tail; | |
1496 | ||
1497 | head = alloc_page_buffers(page, blocksize, 1); | |
1498 | bh = head; | |
1499 | do { | |
1500 | bh->b_state |= b_state; | |
1501 | tail = bh; | |
1502 | bh = bh->b_this_page; | |
1503 | } while (bh); | |
1504 | tail->b_this_page = head; | |
1505 | ||
1506 | spin_lock(&page->mapping->private_lock); | |
1507 | if (PageUptodate(page) || PageDirty(page)) { | |
1508 | bh = head; | |
1509 | do { | |
1510 | if (PageDirty(page)) | |
1511 | set_buffer_dirty(bh); | |
1512 | if (PageUptodate(page)) | |
1513 | set_buffer_uptodate(bh); | |
1514 | bh = bh->b_this_page; | |
1515 | } while (bh != head); | |
1516 | } | |
1517 | attach_page_buffers(page, head); | |
1518 | spin_unlock(&page->mapping->private_lock); | |
1519 | } | |
1520 | EXPORT_SYMBOL(create_empty_buffers); | |
1521 | ||
1522 | /* | |
1523 | * We are taking a block for data and we don't want any output from any | |
1524 | * buffer-cache aliases starting from return from that function and | |
1525 | * until the moment when something will explicitly mark the buffer | |
1526 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1527 | * We don't even need to mark it not-uptodate - nobody can expect | |
1528 | * anything from a newly allocated buffer anyway. We used to used | |
1529 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1530 | * don't want to mark the alias unmapped, for example - it would confuse | |
1531 | * anyone who might pick it with bread() afterwards... | |
1532 | * | |
1533 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1534 | * be writeout I/O going on against recently-freed buffers. We don't | |
1535 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1536 | * only if we really need to. That happens here. | |
1537 | */ | |
1538 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1539 | { | |
1540 | struct buffer_head *old_bh; | |
1541 | ||
1542 | might_sleep(); | |
1543 | ||
385fd4c5 | 1544 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1545 | if (old_bh) { |
1546 | clear_buffer_dirty(old_bh); | |
1547 | wait_on_buffer(old_bh); | |
1548 | clear_buffer_req(old_bh); | |
1549 | __brelse(old_bh); | |
1550 | } | |
1551 | } | |
1552 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1553 | ||
1554 | /* | |
1555 | * NOTE! All mapped/uptodate combinations are valid: | |
1556 | * | |
1557 | * Mapped Uptodate Meaning | |
1558 | * | |
1559 | * No No "unknown" - must do get_block() | |
1560 | * No Yes "hole" - zero-filled | |
1561 | * Yes No "allocated" - allocated on disk, not read in | |
1562 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1563 | * | |
1564 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1565 | */ | |
1566 | ||
1567 | /* | |
1568 | * While block_write_full_page is writing back the dirty buffers under | |
1569 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1570 | * again at any time. We handle that by only looking at the buffer | |
1571 | * state inside lock_buffer(). | |
1572 | * | |
1573 | * If block_write_full_page() is called for regular writeback | |
1574 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1575 | * locked buffer. This only can happen if someone has written the buffer | |
1576 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1577 | * prevents this contention from occurring. | |
1578 | */ | |
1579 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
1580 | get_block_t *get_block, struct writeback_control *wbc) | |
1581 | { | |
1582 | int err; | |
1583 | sector_t block; | |
1584 | sector_t last_block; | |
f0fbd5fc | 1585 | struct buffer_head *bh, *head; |
b0cf2321 | 1586 | const unsigned blocksize = 1 << inode->i_blkbits; |
1da177e4 LT |
1587 | int nr_underway = 0; |
1588 | ||
1589 | BUG_ON(!PageLocked(page)); | |
1590 | ||
1591 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; | |
1592 | ||
1593 | if (!page_has_buffers(page)) { | |
b0cf2321 | 1594 | create_empty_buffers(page, blocksize, |
1da177e4 LT |
1595 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1596 | } | |
1597 | ||
1598 | /* | |
1599 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1600 | * here, and the (potentially unmapped) buffers may become dirty at | |
1601 | * any time. If a buffer becomes dirty here after we've inspected it | |
1602 | * then we just miss that fact, and the page stays dirty. | |
1603 | * | |
1604 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1605 | * handle that here by just cleaning them. | |
1606 | */ | |
1607 | ||
54b21a79 | 1608 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
1609 | head = page_buffers(page); |
1610 | bh = head; | |
1611 | ||
1612 | /* | |
1613 | * Get all the dirty buffers mapped to disk addresses and | |
1614 | * handle any aliases from the underlying blockdev's mapping. | |
1615 | */ | |
1616 | do { | |
1617 | if (block > last_block) { | |
1618 | /* | |
1619 | * mapped buffers outside i_size will occur, because | |
1620 | * this page can be outside i_size when there is a | |
1621 | * truncate in progress. | |
1622 | */ | |
1623 | /* | |
1624 | * The buffer was zeroed by block_write_full_page() | |
1625 | */ | |
1626 | clear_buffer_dirty(bh); | |
1627 | set_buffer_uptodate(bh); | |
1628 | } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { | |
b0cf2321 | 1629 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1630 | err = get_block(inode, block, bh, 1); |
1631 | if (err) | |
1632 | goto recover; | |
1633 | if (buffer_new(bh)) { | |
1634 | /* blockdev mappings never come here */ | |
1635 | clear_buffer_new(bh); | |
1636 | unmap_underlying_metadata(bh->b_bdev, | |
1637 | bh->b_blocknr); | |
1638 | } | |
1639 | } | |
1640 | bh = bh->b_this_page; | |
1641 | block++; | |
1642 | } while (bh != head); | |
1643 | ||
1644 | do { | |
1da177e4 LT |
1645 | if (!buffer_mapped(bh)) |
1646 | continue; | |
1647 | /* | |
1648 | * If it's a fully non-blocking write attempt and we cannot | |
1649 | * lock the buffer then redirty the page. Note that this can | |
1650 | * potentially cause a busy-wait loop from pdflush and kswapd | |
1651 | * activity, but those code paths have their own higher-level | |
1652 | * throttling. | |
1653 | */ | |
1654 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { | |
1655 | lock_buffer(bh); | |
1656 | } else if (test_set_buffer_locked(bh)) { | |
1657 | redirty_page_for_writepage(wbc, page); | |
1658 | continue; | |
1659 | } | |
1660 | if (test_clear_buffer_dirty(bh)) { | |
1661 | mark_buffer_async_write(bh); | |
1662 | } else { | |
1663 | unlock_buffer(bh); | |
1664 | } | |
1665 | } while ((bh = bh->b_this_page) != head); | |
1666 | ||
1667 | /* | |
1668 | * The page and its buffers are protected by PageWriteback(), so we can | |
1669 | * drop the bh refcounts early. | |
1670 | */ | |
1671 | BUG_ON(PageWriteback(page)); | |
1672 | set_page_writeback(page); | |
1da177e4 LT |
1673 | |
1674 | do { | |
1675 | struct buffer_head *next = bh->b_this_page; | |
1676 | if (buffer_async_write(bh)) { | |
1677 | submit_bh(WRITE, bh); | |
1678 | nr_underway++; | |
1679 | } | |
1da177e4 LT |
1680 | bh = next; |
1681 | } while (bh != head); | |
05937baa | 1682 | unlock_page(page); |
1da177e4 LT |
1683 | |
1684 | err = 0; | |
1685 | done: | |
1686 | if (nr_underway == 0) { | |
1687 | /* | |
1688 | * The page was marked dirty, but the buffers were | |
1689 | * clean. Someone wrote them back by hand with | |
1690 | * ll_rw_block/submit_bh. A rare case. | |
1691 | */ | |
1692 | int uptodate = 1; | |
1693 | do { | |
1694 | if (!buffer_uptodate(bh)) { | |
1695 | uptodate = 0; | |
1696 | break; | |
1697 | } | |
1698 | bh = bh->b_this_page; | |
1699 | } while (bh != head); | |
1700 | if (uptodate) | |
1701 | SetPageUptodate(page); | |
1702 | end_page_writeback(page); | |
1703 | /* | |
1704 | * The page and buffer_heads can be released at any time from | |
1705 | * here on. | |
1706 | */ | |
1707 | wbc->pages_skipped++; /* We didn't write this page */ | |
1708 | } | |
1709 | return err; | |
1710 | ||
1711 | recover: | |
1712 | /* | |
1713 | * ENOSPC, or some other error. We may already have added some | |
1714 | * blocks to the file, so we need to write these out to avoid | |
1715 | * exposing stale data. | |
1716 | * The page is currently locked and not marked for writeback | |
1717 | */ | |
1718 | bh = head; | |
1719 | /* Recovery: lock and submit the mapped buffers */ | |
1720 | do { | |
1da177e4 LT |
1721 | if (buffer_mapped(bh) && buffer_dirty(bh)) { |
1722 | lock_buffer(bh); | |
1723 | mark_buffer_async_write(bh); | |
1724 | } else { | |
1725 | /* | |
1726 | * The buffer may have been set dirty during | |
1727 | * attachment to a dirty page. | |
1728 | */ | |
1729 | clear_buffer_dirty(bh); | |
1730 | } | |
1731 | } while ((bh = bh->b_this_page) != head); | |
1732 | SetPageError(page); | |
1733 | BUG_ON(PageWriteback(page)); | |
1734 | set_page_writeback(page); | |
1735 | unlock_page(page); | |
1736 | do { | |
1737 | struct buffer_head *next = bh->b_this_page; | |
1738 | if (buffer_async_write(bh)) { | |
1739 | clear_buffer_dirty(bh); | |
1740 | submit_bh(WRITE, bh); | |
1741 | nr_underway++; | |
1742 | } | |
1da177e4 LT |
1743 | bh = next; |
1744 | } while (bh != head); | |
1745 | goto done; | |
1746 | } | |
1747 | ||
1748 | static int __block_prepare_write(struct inode *inode, struct page *page, | |
1749 | unsigned from, unsigned to, get_block_t *get_block) | |
1750 | { | |
1751 | unsigned block_start, block_end; | |
1752 | sector_t block; | |
1753 | int err = 0; | |
1754 | unsigned blocksize, bbits; | |
1755 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1756 | ||
1757 | BUG_ON(!PageLocked(page)); | |
1758 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1759 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1760 | BUG_ON(from > to); | |
1761 | ||
1762 | blocksize = 1 << inode->i_blkbits; | |
1763 | if (!page_has_buffers(page)) | |
1764 | create_empty_buffers(page, blocksize, 0); | |
1765 | head = page_buffers(page); | |
1766 | ||
1767 | bbits = inode->i_blkbits; | |
1768 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1769 | ||
1770 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1771 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1772 | block_end = block_start + blocksize; | |
1773 | if (block_end <= from || block_start >= to) { | |
1774 | if (PageUptodate(page)) { | |
1775 | if (!buffer_uptodate(bh)) | |
1776 | set_buffer_uptodate(bh); | |
1777 | } | |
1778 | continue; | |
1779 | } | |
1780 | if (buffer_new(bh)) | |
1781 | clear_buffer_new(bh); | |
1782 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1783 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1784 | err = get_block(inode, block, bh, 1); |
1785 | if (err) | |
f3ddbdc6 | 1786 | break; |
1da177e4 | 1787 | if (buffer_new(bh)) { |
1da177e4 LT |
1788 | unmap_underlying_metadata(bh->b_bdev, |
1789 | bh->b_blocknr); | |
1790 | if (PageUptodate(page)) { | |
1791 | set_buffer_uptodate(bh); | |
1792 | continue; | |
1793 | } | |
1794 | if (block_end > to || block_start < from) { | |
1795 | void *kaddr; | |
1796 | ||
1797 | kaddr = kmap_atomic(page, KM_USER0); | |
1798 | if (block_end > to) | |
1799 | memset(kaddr+to, 0, | |
1800 | block_end-to); | |
1801 | if (block_start < from) | |
1802 | memset(kaddr+block_start, | |
1803 | 0, from-block_start); | |
1804 | flush_dcache_page(page); | |
1805 | kunmap_atomic(kaddr, KM_USER0); | |
1806 | } | |
1807 | continue; | |
1808 | } | |
1809 | } | |
1810 | if (PageUptodate(page)) { | |
1811 | if (!buffer_uptodate(bh)) | |
1812 | set_buffer_uptodate(bh); | |
1813 | continue; | |
1814 | } | |
1815 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
1816 | (block_start < from || block_end > to)) { | |
1817 | ll_rw_block(READ, 1, &bh); | |
1818 | *wait_bh++=bh; | |
1819 | } | |
1820 | } | |
1821 | /* | |
1822 | * If we issued read requests - let them complete. | |
1823 | */ | |
1824 | while(wait_bh > wait) { | |
1825 | wait_on_buffer(*--wait_bh); | |
1826 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1827 | err = -EIO; |
1da177e4 | 1828 | } |
152becd2 AA |
1829 | if (!err) { |
1830 | bh = head; | |
1831 | do { | |
1832 | if (buffer_new(bh)) | |
1833 | clear_buffer_new(bh); | |
1834 | } while ((bh = bh->b_this_page) != head); | |
1835 | return 0; | |
1836 | } | |
f3ddbdc6 | 1837 | /* Error case: */ |
1da177e4 LT |
1838 | /* |
1839 | * Zero out any newly allocated blocks to avoid exposing stale | |
1840 | * data. If BH_New is set, we know that the block was newly | |
1841 | * allocated in the above loop. | |
1842 | */ | |
1843 | bh = head; | |
1844 | block_start = 0; | |
1845 | do { | |
1846 | block_end = block_start+blocksize; | |
1847 | if (block_end <= from) | |
1848 | goto next_bh; | |
1849 | if (block_start >= to) | |
1850 | break; | |
1851 | if (buffer_new(bh)) { | |
1852 | void *kaddr; | |
1853 | ||
1854 | clear_buffer_new(bh); | |
1855 | kaddr = kmap_atomic(page, KM_USER0); | |
1856 | memset(kaddr+block_start, 0, bh->b_size); | |
8c581651 | 1857 | flush_dcache_page(page); |
1da177e4 LT |
1858 | kunmap_atomic(kaddr, KM_USER0); |
1859 | set_buffer_uptodate(bh); | |
1860 | mark_buffer_dirty(bh); | |
1861 | } | |
1862 | next_bh: | |
1863 | block_start = block_end; | |
1864 | bh = bh->b_this_page; | |
1865 | } while (bh != head); | |
1866 | return err; | |
1867 | } | |
1868 | ||
1869 | static int __block_commit_write(struct inode *inode, struct page *page, | |
1870 | unsigned from, unsigned to) | |
1871 | { | |
1872 | unsigned block_start, block_end; | |
1873 | int partial = 0; | |
1874 | unsigned blocksize; | |
1875 | struct buffer_head *bh, *head; | |
1876 | ||
1877 | blocksize = 1 << inode->i_blkbits; | |
1878 | ||
1879 | for(bh = head = page_buffers(page), block_start = 0; | |
1880 | bh != head || !block_start; | |
1881 | block_start=block_end, bh = bh->b_this_page) { | |
1882 | block_end = block_start + blocksize; | |
1883 | if (block_end <= from || block_start >= to) { | |
1884 | if (!buffer_uptodate(bh)) | |
1885 | partial = 1; | |
1886 | } else { | |
1887 | set_buffer_uptodate(bh); | |
1888 | mark_buffer_dirty(bh); | |
1889 | } | |
1890 | } | |
1891 | ||
1892 | /* | |
1893 | * If this is a partial write which happened to make all buffers | |
1894 | * uptodate then we can optimize away a bogus readpage() for | |
1895 | * the next read(). Here we 'discover' whether the page went | |
1896 | * uptodate as a result of this (potentially partial) write. | |
1897 | */ | |
1898 | if (!partial) | |
1899 | SetPageUptodate(page); | |
1900 | return 0; | |
1901 | } | |
1902 | ||
1903 | /* | |
1904 | * Generic "read page" function for block devices that have the normal | |
1905 | * get_block functionality. This is most of the block device filesystems. | |
1906 | * Reads the page asynchronously --- the unlock_buffer() and | |
1907 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
1908 | * page struct once IO has completed. | |
1909 | */ | |
1910 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
1911 | { | |
1912 | struct inode *inode = page->mapping->host; | |
1913 | sector_t iblock, lblock; | |
1914 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
1915 | unsigned int blocksize; | |
1916 | int nr, i; | |
1917 | int fully_mapped = 1; | |
1918 | ||
cd7619d6 | 1919 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
1920 | blocksize = 1 << inode->i_blkbits; |
1921 | if (!page_has_buffers(page)) | |
1922 | create_empty_buffers(page, blocksize, 0); | |
1923 | head = page_buffers(page); | |
1924 | ||
1925 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
1926 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; | |
1927 | bh = head; | |
1928 | nr = 0; | |
1929 | i = 0; | |
1930 | ||
1931 | do { | |
1932 | if (buffer_uptodate(bh)) | |
1933 | continue; | |
1934 | ||
1935 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
1936 | int err = 0; |
1937 | ||
1da177e4 LT |
1938 | fully_mapped = 0; |
1939 | if (iblock < lblock) { | |
b0cf2321 | 1940 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
1941 | err = get_block(inode, iblock, bh, 0); |
1942 | if (err) | |
1da177e4 LT |
1943 | SetPageError(page); |
1944 | } | |
1945 | if (!buffer_mapped(bh)) { | |
1946 | void *kaddr = kmap_atomic(page, KM_USER0); | |
1947 | memset(kaddr + i * blocksize, 0, blocksize); | |
1948 | flush_dcache_page(page); | |
1949 | kunmap_atomic(kaddr, KM_USER0); | |
c64610ba AM |
1950 | if (!err) |
1951 | set_buffer_uptodate(bh); | |
1da177e4 LT |
1952 | continue; |
1953 | } | |
1954 | /* | |
1955 | * get_block() might have updated the buffer | |
1956 | * synchronously | |
1957 | */ | |
1958 | if (buffer_uptodate(bh)) | |
1959 | continue; | |
1960 | } | |
1961 | arr[nr++] = bh; | |
1962 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
1963 | ||
1964 | if (fully_mapped) | |
1965 | SetPageMappedToDisk(page); | |
1966 | ||
1967 | if (!nr) { | |
1968 | /* | |
1969 | * All buffers are uptodate - we can set the page uptodate | |
1970 | * as well. But not if get_block() returned an error. | |
1971 | */ | |
1972 | if (!PageError(page)) | |
1973 | SetPageUptodate(page); | |
1974 | unlock_page(page); | |
1975 | return 0; | |
1976 | } | |
1977 | ||
1978 | /* Stage two: lock the buffers */ | |
1979 | for (i = 0; i < nr; i++) { | |
1980 | bh = arr[i]; | |
1981 | lock_buffer(bh); | |
1982 | mark_buffer_async_read(bh); | |
1983 | } | |
1984 | ||
1985 | /* | |
1986 | * Stage 3: start the IO. Check for uptodateness | |
1987 | * inside the buffer lock in case another process reading | |
1988 | * the underlying blockdev brought it uptodate (the sct fix). | |
1989 | */ | |
1990 | for (i = 0; i < nr; i++) { | |
1991 | bh = arr[i]; | |
1992 | if (buffer_uptodate(bh)) | |
1993 | end_buffer_async_read(bh, 1); | |
1994 | else | |
1995 | submit_bh(READ, bh); | |
1996 | } | |
1997 | return 0; | |
1998 | } | |
1999 | ||
2000 | /* utility function for filesystems that need to do work on expanding | |
2001 | * truncates. Uses prepare/commit_write to allow the filesystem to | |
2002 | * deal with the hole. | |
2003 | */ | |
05eb0b51 OH |
2004 | static int __generic_cont_expand(struct inode *inode, loff_t size, |
2005 | pgoff_t index, unsigned int offset) | |
1da177e4 LT |
2006 | { |
2007 | struct address_space *mapping = inode->i_mapping; | |
2008 | struct page *page; | |
05eb0b51 | 2009 | unsigned long limit; |
1da177e4 LT |
2010 | int err; |
2011 | ||
2012 | err = -EFBIG; | |
2013 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
2014 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { | |
2015 | send_sig(SIGXFSZ, current, 0); | |
2016 | goto out; | |
2017 | } | |
2018 | if (size > inode->i_sb->s_maxbytes) | |
2019 | goto out; | |
2020 | ||
1da177e4 LT |
2021 | err = -ENOMEM; |
2022 | page = grab_cache_page(mapping, index); | |
2023 | if (!page) | |
2024 | goto out; | |
2025 | err = mapping->a_ops->prepare_write(NULL, page, offset, offset); | |
05eb0b51 OH |
2026 | if (err) { |
2027 | /* | |
2028 | * ->prepare_write() may have instantiated a few blocks | |
2029 | * outside i_size. Trim these off again. | |
2030 | */ | |
2031 | unlock_page(page); | |
2032 | page_cache_release(page); | |
2033 | vmtruncate(inode, inode->i_size); | |
2034 | goto out; | |
1da177e4 | 2035 | } |
05eb0b51 OH |
2036 | |
2037 | err = mapping->a_ops->commit_write(NULL, page, offset, offset); | |
2038 | ||
1da177e4 LT |
2039 | unlock_page(page); |
2040 | page_cache_release(page); | |
2041 | if (err > 0) | |
2042 | err = 0; | |
2043 | out: | |
2044 | return err; | |
2045 | } | |
2046 | ||
05eb0b51 OH |
2047 | int generic_cont_expand(struct inode *inode, loff_t size) |
2048 | { | |
2049 | pgoff_t index; | |
2050 | unsigned int offset; | |
2051 | ||
2052 | offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */ | |
2053 | ||
2054 | /* ugh. in prepare/commit_write, if from==to==start of block, we | |
2055 | ** skip the prepare. make sure we never send an offset for the start | |
2056 | ** of a block | |
2057 | */ | |
2058 | if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { | |
2059 | /* caller must handle this extra byte. */ | |
2060 | offset++; | |
2061 | } | |
2062 | index = size >> PAGE_CACHE_SHIFT; | |
2063 | ||
2064 | return __generic_cont_expand(inode, size, index, offset); | |
2065 | } | |
2066 | ||
2067 | int generic_cont_expand_simple(struct inode *inode, loff_t size) | |
2068 | { | |
2069 | loff_t pos = size - 1; | |
2070 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
2071 | unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1; | |
2072 | ||
2073 | /* prepare/commit_write can handle even if from==to==start of block. */ | |
2074 | return __generic_cont_expand(inode, size, index, offset); | |
2075 | } | |
2076 | ||
1da177e4 LT |
2077 | /* |
2078 | * For moronic filesystems that do not allow holes in file. | |
2079 | * We may have to extend the file. | |
2080 | */ | |
2081 | ||
2082 | int cont_prepare_write(struct page *page, unsigned offset, | |
2083 | unsigned to, get_block_t *get_block, loff_t *bytes) | |
2084 | { | |
2085 | struct address_space *mapping = page->mapping; | |
2086 | struct inode *inode = mapping->host; | |
2087 | struct page *new_page; | |
2088 | pgoff_t pgpos; | |
2089 | long status; | |
2090 | unsigned zerofrom; | |
2091 | unsigned blocksize = 1 << inode->i_blkbits; | |
2092 | void *kaddr; | |
2093 | ||
2094 | while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { | |
2095 | status = -ENOMEM; | |
2096 | new_page = grab_cache_page(mapping, pgpos); | |
2097 | if (!new_page) | |
2098 | goto out; | |
2099 | /* we might sleep */ | |
2100 | if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { | |
2101 | unlock_page(new_page); | |
2102 | page_cache_release(new_page); | |
2103 | continue; | |
2104 | } | |
2105 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2106 | if (zerofrom & (blocksize-1)) { | |
2107 | *bytes |= (blocksize-1); | |
2108 | (*bytes)++; | |
2109 | } | |
2110 | status = __block_prepare_write(inode, new_page, zerofrom, | |
2111 | PAGE_CACHE_SIZE, get_block); | |
2112 | if (status) | |
2113 | goto out_unmap; | |
2114 | kaddr = kmap_atomic(new_page, KM_USER0); | |
2115 | memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); | |
2116 | flush_dcache_page(new_page); | |
2117 | kunmap_atomic(kaddr, KM_USER0); | |
2118 | generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); | |
2119 | unlock_page(new_page); | |
2120 | page_cache_release(new_page); | |
2121 | } | |
2122 | ||
2123 | if (page->index < pgpos) { | |
2124 | /* completely inside the area */ | |
2125 | zerofrom = offset; | |
2126 | } else { | |
2127 | /* page covers the boundary, find the boundary offset */ | |
2128 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2129 | ||
2130 | /* if we will expand the thing last block will be filled */ | |
2131 | if (to > zerofrom && (zerofrom & (blocksize-1))) { | |
2132 | *bytes |= (blocksize-1); | |
2133 | (*bytes)++; | |
2134 | } | |
2135 | ||
2136 | /* starting below the boundary? Nothing to zero out */ | |
2137 | if (offset <= zerofrom) | |
2138 | zerofrom = offset; | |
2139 | } | |
2140 | status = __block_prepare_write(inode, page, zerofrom, to, get_block); | |
2141 | if (status) | |
2142 | goto out1; | |
2143 | if (zerofrom < offset) { | |
2144 | kaddr = kmap_atomic(page, KM_USER0); | |
2145 | memset(kaddr+zerofrom, 0, offset-zerofrom); | |
2146 | flush_dcache_page(page); | |
2147 | kunmap_atomic(kaddr, KM_USER0); | |
2148 | __block_commit_write(inode, page, zerofrom, offset); | |
2149 | } | |
2150 | return 0; | |
2151 | out1: | |
2152 | ClearPageUptodate(page); | |
2153 | return status; | |
2154 | ||
2155 | out_unmap: | |
2156 | ClearPageUptodate(new_page); | |
2157 | unlock_page(new_page); | |
2158 | page_cache_release(new_page); | |
2159 | out: | |
2160 | return status; | |
2161 | } | |
2162 | ||
2163 | int block_prepare_write(struct page *page, unsigned from, unsigned to, | |
2164 | get_block_t *get_block) | |
2165 | { | |
2166 | struct inode *inode = page->mapping->host; | |
2167 | int err = __block_prepare_write(inode, page, from, to, get_block); | |
2168 | if (err) | |
2169 | ClearPageUptodate(page); | |
2170 | return err; | |
2171 | } | |
2172 | ||
2173 | int block_commit_write(struct page *page, unsigned from, unsigned to) | |
2174 | { | |
2175 | struct inode *inode = page->mapping->host; | |
2176 | __block_commit_write(inode,page,from,to); | |
2177 | return 0; | |
2178 | } | |
2179 | ||
2180 | int generic_commit_write(struct file *file, struct page *page, | |
2181 | unsigned from, unsigned to) | |
2182 | { | |
2183 | struct inode *inode = page->mapping->host; | |
2184 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2185 | __block_commit_write(inode,page,from,to); | |
2186 | /* | |
2187 | * No need to use i_size_read() here, the i_size | |
1b1dcc1b | 2188 | * cannot change under us because we hold i_mutex. |
1da177e4 LT |
2189 | */ |
2190 | if (pos > inode->i_size) { | |
2191 | i_size_write(inode, pos); | |
2192 | mark_inode_dirty(inode); | |
2193 | } | |
2194 | return 0; | |
2195 | } | |
2196 | ||
2197 | ||
2198 | /* | |
2199 | * nobh_prepare_write()'s prereads are special: the buffer_heads are freed | |
2200 | * immediately, while under the page lock. So it needs a special end_io | |
2201 | * handler which does not touch the bh after unlocking it. | |
2202 | * | |
2203 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
2204 | * a race there is benign: unlock_buffer() only use the bh's address for | |
2205 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
2206 | * itself. | |
2207 | */ | |
2208 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2209 | { | |
2210 | if (uptodate) { | |
2211 | set_buffer_uptodate(bh); | |
2212 | } else { | |
2213 | /* This happens, due to failed READA attempts. */ | |
2214 | clear_buffer_uptodate(bh); | |
2215 | } | |
2216 | unlock_buffer(bh); | |
2217 | } | |
2218 | ||
2219 | /* | |
2220 | * On entry, the page is fully not uptodate. | |
2221 | * On exit the page is fully uptodate in the areas outside (from,to) | |
2222 | */ | |
2223 | int nobh_prepare_write(struct page *page, unsigned from, unsigned to, | |
2224 | get_block_t *get_block) | |
2225 | { | |
2226 | struct inode *inode = page->mapping->host; | |
2227 | const unsigned blkbits = inode->i_blkbits; | |
2228 | const unsigned blocksize = 1 << blkbits; | |
2229 | struct buffer_head map_bh; | |
2230 | struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; | |
2231 | unsigned block_in_page; | |
2232 | unsigned block_start; | |
2233 | sector_t block_in_file; | |
2234 | char *kaddr; | |
2235 | int nr_reads = 0; | |
2236 | int i; | |
2237 | int ret = 0; | |
2238 | int is_mapped_to_disk = 1; | |
2239 | int dirtied_it = 0; | |
2240 | ||
2241 | if (PageMappedToDisk(page)) | |
2242 | return 0; | |
2243 | ||
2244 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); | |
2245 | map_bh.b_page = page; | |
2246 | ||
2247 | /* | |
2248 | * We loop across all blocks in the page, whether or not they are | |
2249 | * part of the affected region. This is so we can discover if the | |
2250 | * page is fully mapped-to-disk. | |
2251 | */ | |
2252 | for (block_start = 0, block_in_page = 0; | |
2253 | block_start < PAGE_CACHE_SIZE; | |
2254 | block_in_page++, block_start += blocksize) { | |
2255 | unsigned block_end = block_start + blocksize; | |
2256 | int create; | |
2257 | ||
2258 | map_bh.b_state = 0; | |
2259 | create = 1; | |
2260 | if (block_start >= to) | |
2261 | create = 0; | |
b0cf2321 | 2262 | map_bh.b_size = blocksize; |
1da177e4 LT |
2263 | ret = get_block(inode, block_in_file + block_in_page, |
2264 | &map_bh, create); | |
2265 | if (ret) | |
2266 | goto failed; | |
2267 | if (!buffer_mapped(&map_bh)) | |
2268 | is_mapped_to_disk = 0; | |
2269 | if (buffer_new(&map_bh)) | |
2270 | unmap_underlying_metadata(map_bh.b_bdev, | |
2271 | map_bh.b_blocknr); | |
2272 | if (PageUptodate(page)) | |
2273 | continue; | |
2274 | if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { | |
2275 | kaddr = kmap_atomic(page, KM_USER0); | |
2276 | if (block_start < from) { | |
2277 | memset(kaddr+block_start, 0, from-block_start); | |
2278 | dirtied_it = 1; | |
2279 | } | |
2280 | if (block_end > to) { | |
2281 | memset(kaddr + to, 0, block_end - to); | |
2282 | dirtied_it = 1; | |
2283 | } | |
2284 | flush_dcache_page(page); | |
2285 | kunmap_atomic(kaddr, KM_USER0); | |
2286 | continue; | |
2287 | } | |
2288 | if (buffer_uptodate(&map_bh)) | |
2289 | continue; /* reiserfs does this */ | |
2290 | if (block_start < from || block_end > to) { | |
2291 | struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); | |
2292 | ||
2293 | if (!bh) { | |
2294 | ret = -ENOMEM; | |
2295 | goto failed; | |
2296 | } | |
2297 | bh->b_state = map_bh.b_state; | |
2298 | atomic_set(&bh->b_count, 0); | |
2299 | bh->b_this_page = NULL; | |
2300 | bh->b_page = page; | |
2301 | bh->b_blocknr = map_bh.b_blocknr; | |
2302 | bh->b_size = blocksize; | |
2303 | bh->b_data = (char *)(long)block_start; | |
2304 | bh->b_bdev = map_bh.b_bdev; | |
2305 | bh->b_private = NULL; | |
2306 | read_bh[nr_reads++] = bh; | |
2307 | } | |
2308 | } | |
2309 | ||
2310 | if (nr_reads) { | |
2311 | struct buffer_head *bh; | |
2312 | ||
2313 | /* | |
2314 | * The page is locked, so these buffers are protected from | |
2315 | * any VM or truncate activity. Hence we don't need to care | |
2316 | * for the buffer_head refcounts. | |
2317 | */ | |
2318 | for (i = 0; i < nr_reads; i++) { | |
2319 | bh = read_bh[i]; | |
2320 | lock_buffer(bh); | |
2321 | bh->b_end_io = end_buffer_read_nobh; | |
2322 | submit_bh(READ, bh); | |
2323 | } | |
2324 | for (i = 0; i < nr_reads; i++) { | |
2325 | bh = read_bh[i]; | |
2326 | wait_on_buffer(bh); | |
2327 | if (!buffer_uptodate(bh)) | |
2328 | ret = -EIO; | |
2329 | free_buffer_head(bh); | |
2330 | read_bh[i] = NULL; | |
2331 | } | |
2332 | if (ret) | |
2333 | goto failed; | |
2334 | } | |
2335 | ||
2336 | if (is_mapped_to_disk) | |
2337 | SetPageMappedToDisk(page); | |
2338 | SetPageUptodate(page); | |
2339 | ||
2340 | /* | |
2341 | * Setting the page dirty here isn't necessary for the prepare_write | |
2342 | * function - commit_write will do that. But if/when this function is | |
2343 | * used within the pagefault handler to ensure that all mmapped pages | |
2344 | * have backing space in the filesystem, we will need to dirty the page | |
2345 | * if its contents were altered. | |
2346 | */ | |
2347 | if (dirtied_it) | |
2348 | set_page_dirty(page); | |
2349 | ||
2350 | return 0; | |
2351 | ||
2352 | failed: | |
2353 | for (i = 0; i < nr_reads; i++) { | |
2354 | if (read_bh[i]) | |
2355 | free_buffer_head(read_bh[i]); | |
2356 | } | |
2357 | ||
2358 | /* | |
2359 | * Error recovery is pretty slack. Clear the page and mark it dirty | |
2360 | * so we'll later zero out any blocks which _were_ allocated. | |
2361 | */ | |
2362 | kaddr = kmap_atomic(page, KM_USER0); | |
2363 | memset(kaddr, 0, PAGE_CACHE_SIZE); | |
8c581651 | 2364 | flush_dcache_page(page); |
1da177e4 LT |
2365 | kunmap_atomic(kaddr, KM_USER0); |
2366 | SetPageUptodate(page); | |
2367 | set_page_dirty(page); | |
2368 | return ret; | |
2369 | } | |
2370 | EXPORT_SYMBOL(nobh_prepare_write); | |
2371 | ||
2372 | int nobh_commit_write(struct file *file, struct page *page, | |
2373 | unsigned from, unsigned to) | |
2374 | { | |
2375 | struct inode *inode = page->mapping->host; | |
2376 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2377 | ||
2378 | set_page_dirty(page); | |
2379 | if (pos > inode->i_size) { | |
2380 | i_size_write(inode, pos); | |
2381 | mark_inode_dirty(inode); | |
2382 | } | |
2383 | return 0; | |
2384 | } | |
2385 | EXPORT_SYMBOL(nobh_commit_write); | |
2386 | ||
2387 | /* | |
2388 | * nobh_writepage() - based on block_full_write_page() except | |
2389 | * that it tries to operate without attaching bufferheads to | |
2390 | * the page. | |
2391 | */ | |
2392 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2393 | struct writeback_control *wbc) | |
2394 | { | |
2395 | struct inode * const inode = page->mapping->host; | |
2396 | loff_t i_size = i_size_read(inode); | |
2397 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2398 | unsigned offset; | |
2399 | void *kaddr; | |
2400 | int ret; | |
2401 | ||
2402 | /* Is the page fully inside i_size? */ | |
2403 | if (page->index < end_index) | |
2404 | goto out; | |
2405 | ||
2406 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2407 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2408 | if (page->index >= end_index+1 || !offset) { | |
2409 | /* | |
2410 | * The page may have dirty, unmapped buffers. For example, | |
2411 | * they may have been added in ext3_writepage(). Make them | |
2412 | * freeable here, so the page does not leak. | |
2413 | */ | |
2414 | #if 0 | |
2415 | /* Not really sure about this - do we need this ? */ | |
2416 | if (page->mapping->a_ops->invalidatepage) | |
2417 | page->mapping->a_ops->invalidatepage(page, offset); | |
2418 | #endif | |
2419 | unlock_page(page); | |
2420 | return 0; /* don't care */ | |
2421 | } | |
2422 | ||
2423 | /* | |
2424 | * The page straddles i_size. It must be zeroed out on each and every | |
2425 | * writepage invocation because it may be mmapped. "A file is mapped | |
2426 | * in multiples of the page size. For a file that is not a multiple of | |
2427 | * the page size, the remaining memory is zeroed when mapped, and | |
2428 | * writes to that region are not written out to the file." | |
2429 | */ | |
2430 | kaddr = kmap_atomic(page, KM_USER0); | |
2431 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2432 | flush_dcache_page(page); | |
2433 | kunmap_atomic(kaddr, KM_USER0); | |
2434 | out: | |
2435 | ret = mpage_writepage(page, get_block, wbc); | |
2436 | if (ret == -EAGAIN) | |
2437 | ret = __block_write_full_page(inode, page, get_block, wbc); | |
2438 | return ret; | |
2439 | } | |
2440 | EXPORT_SYMBOL(nobh_writepage); | |
2441 | ||
2442 | /* | |
2443 | * This function assumes that ->prepare_write() uses nobh_prepare_write(). | |
2444 | */ | |
2445 | int nobh_truncate_page(struct address_space *mapping, loff_t from) | |
2446 | { | |
2447 | struct inode *inode = mapping->host; | |
2448 | unsigned blocksize = 1 << inode->i_blkbits; | |
2449 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2450 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2451 | unsigned to; | |
2452 | struct page *page; | |
f5e54d6e | 2453 | const struct address_space_operations *a_ops = mapping->a_ops; |
1da177e4 LT |
2454 | char *kaddr; |
2455 | int ret = 0; | |
2456 | ||
2457 | if ((offset & (blocksize - 1)) == 0) | |
2458 | goto out; | |
2459 | ||
2460 | ret = -ENOMEM; | |
2461 | page = grab_cache_page(mapping, index); | |
2462 | if (!page) | |
2463 | goto out; | |
2464 | ||
2465 | to = (offset + blocksize) & ~(blocksize - 1); | |
2466 | ret = a_ops->prepare_write(NULL, page, offset, to); | |
2467 | if (ret == 0) { | |
2468 | kaddr = kmap_atomic(page, KM_USER0); | |
2469 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2470 | flush_dcache_page(page); | |
2471 | kunmap_atomic(kaddr, KM_USER0); | |
2472 | set_page_dirty(page); | |
2473 | } | |
2474 | unlock_page(page); | |
2475 | page_cache_release(page); | |
2476 | out: | |
2477 | return ret; | |
2478 | } | |
2479 | EXPORT_SYMBOL(nobh_truncate_page); | |
2480 | ||
2481 | int block_truncate_page(struct address_space *mapping, | |
2482 | loff_t from, get_block_t *get_block) | |
2483 | { | |
2484 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2485 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2486 | unsigned blocksize; | |
54b21a79 | 2487 | sector_t iblock; |
1da177e4 LT |
2488 | unsigned length, pos; |
2489 | struct inode *inode = mapping->host; | |
2490 | struct page *page; | |
2491 | struct buffer_head *bh; | |
2492 | void *kaddr; | |
2493 | int err; | |
2494 | ||
2495 | blocksize = 1 << inode->i_blkbits; | |
2496 | length = offset & (blocksize - 1); | |
2497 | ||
2498 | /* Block boundary? Nothing to do */ | |
2499 | if (!length) | |
2500 | return 0; | |
2501 | ||
2502 | length = blocksize - length; | |
54b21a79 | 2503 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2504 | |
2505 | page = grab_cache_page(mapping, index); | |
2506 | err = -ENOMEM; | |
2507 | if (!page) | |
2508 | goto out; | |
2509 | ||
2510 | if (!page_has_buffers(page)) | |
2511 | create_empty_buffers(page, blocksize, 0); | |
2512 | ||
2513 | /* Find the buffer that contains "offset" */ | |
2514 | bh = page_buffers(page); | |
2515 | pos = blocksize; | |
2516 | while (offset >= pos) { | |
2517 | bh = bh->b_this_page; | |
2518 | iblock++; | |
2519 | pos += blocksize; | |
2520 | } | |
2521 | ||
2522 | err = 0; | |
2523 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2524 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2525 | err = get_block(inode, iblock, bh, 0); |
2526 | if (err) | |
2527 | goto unlock; | |
2528 | /* unmapped? It's a hole - nothing to do */ | |
2529 | if (!buffer_mapped(bh)) | |
2530 | goto unlock; | |
2531 | } | |
2532 | ||
2533 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2534 | if (PageUptodate(page)) | |
2535 | set_buffer_uptodate(bh); | |
2536 | ||
2537 | if (!buffer_uptodate(bh) && !buffer_delay(bh)) { | |
2538 | err = -EIO; | |
2539 | ll_rw_block(READ, 1, &bh); | |
2540 | wait_on_buffer(bh); | |
2541 | /* Uhhuh. Read error. Complain and punt. */ | |
2542 | if (!buffer_uptodate(bh)) | |
2543 | goto unlock; | |
2544 | } | |
2545 | ||
2546 | kaddr = kmap_atomic(page, KM_USER0); | |
2547 | memset(kaddr + offset, 0, length); | |
2548 | flush_dcache_page(page); | |
2549 | kunmap_atomic(kaddr, KM_USER0); | |
2550 | ||
2551 | mark_buffer_dirty(bh); | |
2552 | err = 0; | |
2553 | ||
2554 | unlock: | |
2555 | unlock_page(page); | |
2556 | page_cache_release(page); | |
2557 | out: | |
2558 | return err; | |
2559 | } | |
2560 | ||
2561 | /* | |
2562 | * The generic ->writepage function for buffer-backed address_spaces | |
2563 | */ | |
2564 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2565 | struct writeback_control *wbc) | |
2566 | { | |
2567 | struct inode * const inode = page->mapping->host; | |
2568 | loff_t i_size = i_size_read(inode); | |
2569 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2570 | unsigned offset; | |
2571 | void *kaddr; | |
2572 | ||
2573 | /* Is the page fully inside i_size? */ | |
2574 | if (page->index < end_index) | |
2575 | return __block_write_full_page(inode, page, get_block, wbc); | |
2576 | ||
2577 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2578 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2579 | if (page->index >= end_index+1 || !offset) { | |
2580 | /* | |
2581 | * The page may have dirty, unmapped buffers. For example, | |
2582 | * they may have been added in ext3_writepage(). Make them | |
2583 | * freeable here, so the page does not leak. | |
2584 | */ | |
aaa4059b | 2585 | do_invalidatepage(page, 0); |
1da177e4 LT |
2586 | unlock_page(page); |
2587 | return 0; /* don't care */ | |
2588 | } | |
2589 | ||
2590 | /* | |
2591 | * The page straddles i_size. It must be zeroed out on each and every | |
2592 | * writepage invokation because it may be mmapped. "A file is mapped | |
2593 | * in multiples of the page size. For a file that is not a multiple of | |
2594 | * the page size, the remaining memory is zeroed when mapped, and | |
2595 | * writes to that region are not written out to the file." | |
2596 | */ | |
2597 | kaddr = kmap_atomic(page, KM_USER0); | |
2598 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2599 | flush_dcache_page(page); | |
2600 | kunmap_atomic(kaddr, KM_USER0); | |
2601 | return __block_write_full_page(inode, page, get_block, wbc); | |
2602 | } | |
2603 | ||
2604 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, | |
2605 | get_block_t *get_block) | |
2606 | { | |
2607 | struct buffer_head tmp; | |
2608 | struct inode *inode = mapping->host; | |
2609 | tmp.b_state = 0; | |
2610 | tmp.b_blocknr = 0; | |
b0cf2321 | 2611 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2612 | get_block(inode, block, &tmp, 0); |
2613 | return tmp.b_blocknr; | |
2614 | } | |
2615 | ||
2616 | static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) | |
2617 | { | |
2618 | struct buffer_head *bh = bio->bi_private; | |
2619 | ||
2620 | if (bio->bi_size) | |
2621 | return 1; | |
2622 | ||
2623 | if (err == -EOPNOTSUPP) { | |
2624 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
2625 | set_bit(BH_Eopnotsupp, &bh->b_state); | |
2626 | } | |
2627 | ||
2628 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); | |
2629 | bio_put(bio); | |
2630 | return 0; | |
2631 | } | |
2632 | ||
2633 | int submit_bh(int rw, struct buffer_head * bh) | |
2634 | { | |
2635 | struct bio *bio; | |
2636 | int ret = 0; | |
2637 | ||
2638 | BUG_ON(!buffer_locked(bh)); | |
2639 | BUG_ON(!buffer_mapped(bh)); | |
2640 | BUG_ON(!bh->b_end_io); | |
2641 | ||
2642 | if (buffer_ordered(bh) && (rw == WRITE)) | |
2643 | rw = WRITE_BARRIER; | |
2644 | ||
2645 | /* | |
2646 | * Only clear out a write error when rewriting, should this | |
2647 | * include WRITE_SYNC as well? | |
2648 | */ | |
2649 | if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) | |
2650 | clear_buffer_write_io_error(bh); | |
2651 | ||
2652 | /* | |
2653 | * from here on down, it's all bio -- do the initial mapping, | |
2654 | * submit_bio -> generic_make_request may further map this bio around | |
2655 | */ | |
2656 | bio = bio_alloc(GFP_NOIO, 1); | |
2657 | ||
2658 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2659 | bio->bi_bdev = bh->b_bdev; | |
2660 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2661 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2662 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2663 | ||
2664 | bio->bi_vcnt = 1; | |
2665 | bio->bi_idx = 0; | |
2666 | bio->bi_size = bh->b_size; | |
2667 | ||
2668 | bio->bi_end_io = end_bio_bh_io_sync; | |
2669 | bio->bi_private = bh; | |
2670 | ||
2671 | bio_get(bio); | |
2672 | submit_bio(rw, bio); | |
2673 | ||
2674 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2675 | ret = -EOPNOTSUPP; | |
2676 | ||
2677 | bio_put(bio); | |
2678 | return ret; | |
2679 | } | |
2680 | ||
2681 | /** | |
2682 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
a7662236 | 2683 | * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) |
1da177e4 LT |
2684 | * @nr: number of &struct buffer_heads in the array |
2685 | * @bhs: array of pointers to &struct buffer_head | |
2686 | * | |
a7662236 JK |
2687 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
2688 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
2689 | * %SWRITE is like %WRITE only we make sure that the *current* data in buffers | |
2690 | * are sent to disk. The fourth %READA option is described in the documentation | |
2691 | * for generic_make_request() which ll_rw_block() calls. | |
1da177e4 LT |
2692 | * |
2693 | * This function drops any buffer that it cannot get a lock on (with the | |
a7662236 JK |
2694 | * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be |
2695 | * clean when doing a write request, and any buffer that appears to be | |
2696 | * up-to-date when doing read request. Further it marks as clean buffers that | |
2697 | * are processed for writing (the buffer cache won't assume that they are | |
2698 | * actually clean until the buffer gets unlocked). | |
1da177e4 LT |
2699 | * |
2700 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
2701 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
2702 | * any waiters. | |
2703 | * | |
2704 | * All of the buffers must be for the same device, and must also be a | |
2705 | * multiple of the current approved size for the device. | |
2706 | */ | |
2707 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
2708 | { | |
2709 | int i; | |
2710 | ||
2711 | for (i = 0; i < nr; i++) { | |
2712 | struct buffer_head *bh = bhs[i]; | |
2713 | ||
a7662236 JK |
2714 | if (rw == SWRITE) |
2715 | lock_buffer(bh); | |
2716 | else if (test_set_buffer_locked(bh)) | |
1da177e4 LT |
2717 | continue; |
2718 | ||
a7662236 | 2719 | if (rw == WRITE || rw == SWRITE) { |
1da177e4 | 2720 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 2721 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 2722 | get_bh(bh); |
1da177e4 LT |
2723 | submit_bh(WRITE, bh); |
2724 | continue; | |
2725 | } | |
2726 | } else { | |
1da177e4 | 2727 | if (!buffer_uptodate(bh)) { |
76c3073a | 2728 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 2729 | get_bh(bh); |
1da177e4 LT |
2730 | submit_bh(rw, bh); |
2731 | continue; | |
2732 | } | |
2733 | } | |
2734 | unlock_buffer(bh); | |
1da177e4 LT |
2735 | } |
2736 | } | |
2737 | ||
2738 | /* | |
2739 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
2740 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
2741 | * the buffer_head. | |
2742 | */ | |
2743 | int sync_dirty_buffer(struct buffer_head *bh) | |
2744 | { | |
2745 | int ret = 0; | |
2746 | ||
2747 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
2748 | lock_buffer(bh); | |
2749 | if (test_clear_buffer_dirty(bh)) { | |
2750 | get_bh(bh); | |
2751 | bh->b_end_io = end_buffer_write_sync; | |
2752 | ret = submit_bh(WRITE, bh); | |
2753 | wait_on_buffer(bh); | |
2754 | if (buffer_eopnotsupp(bh)) { | |
2755 | clear_buffer_eopnotsupp(bh); | |
2756 | ret = -EOPNOTSUPP; | |
2757 | } | |
2758 | if (!ret && !buffer_uptodate(bh)) | |
2759 | ret = -EIO; | |
2760 | } else { | |
2761 | unlock_buffer(bh); | |
2762 | } | |
2763 | return ret; | |
2764 | } | |
2765 | ||
2766 | /* | |
2767 | * try_to_free_buffers() checks if all the buffers on this particular page | |
2768 | * are unused, and releases them if so. | |
2769 | * | |
2770 | * Exclusion against try_to_free_buffers may be obtained by either | |
2771 | * locking the page or by holding its mapping's private_lock. | |
2772 | * | |
2773 | * If the page is dirty but all the buffers are clean then we need to | |
2774 | * be sure to mark the page clean as well. This is because the page | |
2775 | * may be against a block device, and a later reattachment of buffers | |
2776 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
2777 | * filesystem data on the same device. | |
2778 | * | |
2779 | * The same applies to regular filesystem pages: if all the buffers are | |
2780 | * clean then we set the page clean and proceed. To do that, we require | |
2781 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
2782 | * private_lock. | |
2783 | * | |
2784 | * try_to_free_buffers() is non-blocking. | |
2785 | */ | |
2786 | static inline int buffer_busy(struct buffer_head *bh) | |
2787 | { | |
2788 | return atomic_read(&bh->b_count) | | |
2789 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
2790 | } | |
2791 | ||
2792 | static int | |
2793 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
2794 | { | |
2795 | struct buffer_head *head = page_buffers(page); | |
2796 | struct buffer_head *bh; | |
2797 | ||
2798 | bh = head; | |
2799 | do { | |
de7d5a3b | 2800 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
2801 | set_bit(AS_EIO, &page->mapping->flags); |
2802 | if (buffer_busy(bh)) | |
2803 | goto failed; | |
2804 | bh = bh->b_this_page; | |
2805 | } while (bh != head); | |
2806 | ||
2807 | do { | |
2808 | struct buffer_head *next = bh->b_this_page; | |
2809 | ||
2810 | if (!list_empty(&bh->b_assoc_buffers)) | |
2811 | __remove_assoc_queue(bh); | |
2812 | bh = next; | |
2813 | } while (bh != head); | |
2814 | *buffers_to_free = head; | |
2815 | __clear_page_buffers(page); | |
2816 | return 1; | |
2817 | failed: | |
2818 | return 0; | |
2819 | } | |
2820 | ||
2821 | int try_to_free_buffers(struct page *page) | |
2822 | { | |
2823 | struct address_space * const mapping = page->mapping; | |
2824 | struct buffer_head *buffers_to_free = NULL; | |
2825 | int ret = 0; | |
2826 | ||
2827 | BUG_ON(!PageLocked(page)); | |
2828 | if (PageWriteback(page)) | |
2829 | return 0; | |
2830 | ||
2831 | if (mapping == NULL) { /* can this still happen? */ | |
2832 | ret = drop_buffers(page, &buffers_to_free); | |
2833 | goto out; | |
2834 | } | |
2835 | ||
2836 | spin_lock(&mapping->private_lock); | |
2837 | ret = drop_buffers(page, &buffers_to_free); | |
d08b3851 | 2838 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
2839 | if (ret) { |
2840 | /* | |
2841 | * If the filesystem writes its buffers by hand (eg ext3) | |
2842 | * then we can have clean buffers against a dirty page. We | |
2843 | * clean the page here; otherwise later reattachment of buffers | |
2844 | * could encounter a non-uptodate page, which is unresolvable. | |
2845 | * This only applies in the rare case where try_to_free_buffers | |
2846 | * succeeds but the page is not freed. | |
2847 | */ | |
2848 | clear_page_dirty(page); | |
2849 | } | |
1da177e4 LT |
2850 | out: |
2851 | if (buffers_to_free) { | |
2852 | struct buffer_head *bh = buffers_to_free; | |
2853 | ||
2854 | do { | |
2855 | struct buffer_head *next = bh->b_this_page; | |
2856 | free_buffer_head(bh); | |
2857 | bh = next; | |
2858 | } while (bh != buffers_to_free); | |
2859 | } | |
2860 | return ret; | |
2861 | } | |
2862 | EXPORT_SYMBOL(try_to_free_buffers); | |
2863 | ||
3978d717 | 2864 | void block_sync_page(struct page *page) |
1da177e4 LT |
2865 | { |
2866 | struct address_space *mapping; | |
2867 | ||
2868 | smp_mb(); | |
2869 | mapping = page_mapping(page); | |
2870 | if (mapping) | |
2871 | blk_run_backing_dev(mapping->backing_dev_info, page); | |
1da177e4 LT |
2872 | } |
2873 | ||
2874 | /* | |
2875 | * There are no bdflush tunables left. But distributions are | |
2876 | * still running obsolete flush daemons, so we terminate them here. | |
2877 | * | |
2878 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
2879 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. | |
2880 | */ | |
2881 | asmlinkage long sys_bdflush(int func, long data) | |
2882 | { | |
2883 | static int msg_count; | |
2884 | ||
2885 | if (!capable(CAP_SYS_ADMIN)) | |
2886 | return -EPERM; | |
2887 | ||
2888 | if (msg_count < 5) { | |
2889 | msg_count++; | |
2890 | printk(KERN_INFO | |
2891 | "warning: process `%s' used the obsolete bdflush" | |
2892 | " system call\n", current->comm); | |
2893 | printk(KERN_INFO "Fix your initscripts?\n"); | |
2894 | } | |
2895 | ||
2896 | if (func == 1) | |
2897 | do_exit(0); | |
2898 | return 0; | |
2899 | } | |
2900 | ||
2901 | /* | |
2902 | * Buffer-head allocation | |
2903 | */ | |
2904 | static kmem_cache_t *bh_cachep; | |
2905 | ||
2906 | /* | |
2907 | * Once the number of bh's in the machine exceeds this level, we start | |
2908 | * stripping them in writeback. | |
2909 | */ | |
2910 | static int max_buffer_heads; | |
2911 | ||
2912 | int buffer_heads_over_limit; | |
2913 | ||
2914 | struct bh_accounting { | |
2915 | int nr; /* Number of live bh's */ | |
2916 | int ratelimit; /* Limit cacheline bouncing */ | |
2917 | }; | |
2918 | ||
2919 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
2920 | ||
2921 | static void recalc_bh_state(void) | |
2922 | { | |
2923 | int i; | |
2924 | int tot = 0; | |
2925 | ||
2926 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) | |
2927 | return; | |
2928 | __get_cpu_var(bh_accounting).ratelimit = 0; | |
8a143426 | 2929 | for_each_online_cpu(i) |
1da177e4 LT |
2930 | tot += per_cpu(bh_accounting, i).nr; |
2931 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
2932 | } | |
2933 | ||
dd0fc66f | 2934 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 LT |
2935 | { |
2936 | struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); | |
2937 | if (ret) { | |
736c7b80 | 2938 | get_cpu_var(bh_accounting).nr++; |
1da177e4 | 2939 | recalc_bh_state(); |
736c7b80 | 2940 | put_cpu_var(bh_accounting); |
1da177e4 LT |
2941 | } |
2942 | return ret; | |
2943 | } | |
2944 | EXPORT_SYMBOL(alloc_buffer_head); | |
2945 | ||
2946 | void free_buffer_head(struct buffer_head *bh) | |
2947 | { | |
2948 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
2949 | kmem_cache_free(bh_cachep, bh); | |
736c7b80 | 2950 | get_cpu_var(bh_accounting).nr--; |
1da177e4 | 2951 | recalc_bh_state(); |
736c7b80 | 2952 | put_cpu_var(bh_accounting); |
1da177e4 LT |
2953 | } |
2954 | EXPORT_SYMBOL(free_buffer_head); | |
2955 | ||
2956 | static void | |
2957 | init_buffer_head(void *data, kmem_cache_t *cachep, unsigned long flags) | |
2958 | { | |
2959 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == | |
2960 | SLAB_CTOR_CONSTRUCTOR) { | |
2961 | struct buffer_head * bh = (struct buffer_head *)data; | |
2962 | ||
2963 | memset(bh, 0, sizeof(*bh)); | |
2964 | INIT_LIST_HEAD(&bh->b_assoc_buffers); | |
2965 | } | |
2966 | } | |
2967 | ||
2968 | #ifdef CONFIG_HOTPLUG_CPU | |
2969 | static void buffer_exit_cpu(int cpu) | |
2970 | { | |
2971 | int i; | |
2972 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
2973 | ||
2974 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
2975 | brelse(b->bhs[i]); | |
2976 | b->bhs[i] = NULL; | |
2977 | } | |
8a143426 ED |
2978 | get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; |
2979 | per_cpu(bh_accounting, cpu).nr = 0; | |
2980 | put_cpu_var(bh_accounting); | |
1da177e4 LT |
2981 | } |
2982 | ||
2983 | static int buffer_cpu_notify(struct notifier_block *self, | |
2984 | unsigned long action, void *hcpu) | |
2985 | { | |
2986 | if (action == CPU_DEAD) | |
2987 | buffer_exit_cpu((unsigned long)hcpu); | |
2988 | return NOTIFY_OK; | |
2989 | } | |
2990 | #endif /* CONFIG_HOTPLUG_CPU */ | |
2991 | ||
2992 | void __init buffer_init(void) | |
2993 | { | |
2994 | int nrpages; | |
2995 | ||
2996 | bh_cachep = kmem_cache_create("buffer_head", | |
b0196009 PJ |
2997 | sizeof(struct buffer_head), 0, |
2998 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
2999 | SLAB_MEM_SPREAD), | |
3000 | init_buffer_head, | |
3001 | NULL); | |
1da177e4 LT |
3002 | |
3003 | /* | |
3004 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3005 | */ | |
3006 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3007 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3008 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3009 | } | |
3010 | ||
3011 | EXPORT_SYMBOL(__bforget); | |
3012 | EXPORT_SYMBOL(__brelse); | |
3013 | EXPORT_SYMBOL(__wait_on_buffer); | |
3014 | EXPORT_SYMBOL(block_commit_write); | |
3015 | EXPORT_SYMBOL(block_prepare_write); | |
3016 | EXPORT_SYMBOL(block_read_full_page); | |
3017 | EXPORT_SYMBOL(block_sync_page); | |
3018 | EXPORT_SYMBOL(block_truncate_page); | |
3019 | EXPORT_SYMBOL(block_write_full_page); | |
3020 | EXPORT_SYMBOL(cont_prepare_write); | |
1da177e4 LT |
3021 | EXPORT_SYMBOL(end_buffer_read_sync); |
3022 | EXPORT_SYMBOL(end_buffer_write_sync); | |
3023 | EXPORT_SYMBOL(file_fsync); | |
3024 | EXPORT_SYMBOL(fsync_bdev); | |
3025 | EXPORT_SYMBOL(generic_block_bmap); | |
3026 | EXPORT_SYMBOL(generic_commit_write); | |
3027 | EXPORT_SYMBOL(generic_cont_expand); | |
05eb0b51 | 3028 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 LT |
3029 | EXPORT_SYMBOL(init_buffer); |
3030 | EXPORT_SYMBOL(invalidate_bdev); | |
3031 | EXPORT_SYMBOL(ll_rw_block); | |
3032 | EXPORT_SYMBOL(mark_buffer_dirty); | |
3033 | EXPORT_SYMBOL(submit_bh); | |
3034 | EXPORT_SYMBOL(sync_dirty_buffer); | |
3035 | EXPORT_SYMBOL(unlock_buffer); |