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> | |
16f7e0fe | 27 | #include <linux/capability.h> |
1da177e4 LT |
28 | #include <linux/blkdev.h> |
29 | #include <linux/file.h> | |
30 | #include <linux/quotaops.h> | |
31 | #include <linux/highmem.h> | |
32 | #include <linux/module.h> | |
33 | #include <linux/writeback.h> | |
34 | #include <linux/hash.h> | |
35 | #include <linux/suspend.h> | |
36 | #include <linux/buffer_head.h> | |
55e829af | 37 | #include <linux/task_io_accounting_ops.h> |
1da177e4 LT |
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); | |
1da177e4 LT |
46 | |
47 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) | |
48 | ||
49 | inline void | |
50 | init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) | |
51 | { | |
52 | bh->b_end_io = handler; | |
53 | bh->b_private = private; | |
54 | } | |
55 | ||
56 | static int sync_buffer(void *word) | |
57 | { | |
58 | struct block_device *bd; | |
59 | struct buffer_head *bh | |
60 | = container_of(word, struct buffer_head, b_state); | |
61 | ||
62 | smp_mb(); | |
63 | bd = bh->b_bdev; | |
64 | if (bd) | |
65 | blk_run_address_space(bd->bd_inode->i_mapping); | |
66 | io_schedule(); | |
67 | return 0; | |
68 | } | |
69 | ||
70 | void fastcall __lock_buffer(struct buffer_head *bh) | |
71 | { | |
72 | wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, | |
73 | TASK_UNINTERRUPTIBLE); | |
74 | } | |
75 | EXPORT_SYMBOL(__lock_buffer); | |
76 | ||
77 | void fastcall unlock_buffer(struct buffer_head *bh) | |
78 | { | |
72ed3d03 | 79 | smp_mb__before_clear_bit(); |
1da177e4 LT |
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 | /* | |
68671f35 DM |
113 | * End-of-IO handler helper function which does not touch the bh after |
114 | * unlocking it. | |
115 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
116 | * a race there is benign: unlock_buffer() only use the bh's address for | |
117 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
118 | * itself. | |
1da177e4 | 119 | */ |
68671f35 | 120 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
121 | { |
122 | if (uptodate) { | |
123 | set_buffer_uptodate(bh); | |
124 | } else { | |
125 | /* This happens, due to failed READA attempts. */ | |
126 | clear_buffer_uptodate(bh); | |
127 | } | |
128 | unlock_buffer(bh); | |
68671f35 DM |
129 | } |
130 | ||
131 | /* | |
132 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
133 | * unlock the buffer. This is what ll_rw_block uses too. | |
134 | */ | |
135 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
136 | { | |
137 | __end_buffer_read_notouch(bh, uptodate); | |
1da177e4 LT |
138 | put_bh(bh); |
139 | } | |
140 | ||
141 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
142 | { | |
143 | char b[BDEVNAME_SIZE]; | |
144 | ||
145 | if (uptodate) { | |
146 | set_buffer_uptodate(bh); | |
147 | } else { | |
148 | if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { | |
149 | buffer_io_error(bh); | |
150 | printk(KERN_WARNING "lost page write due to " | |
151 | "I/O error on %s\n", | |
152 | bdevname(bh->b_bdev, b)); | |
153 | } | |
154 | set_buffer_write_io_error(bh); | |
155 | clear_buffer_uptodate(bh); | |
156 | } | |
157 | unlock_buffer(bh); | |
158 | put_bh(bh); | |
159 | } | |
160 | ||
161 | /* | |
162 | * Write out and wait upon all the dirty data associated with a block | |
163 | * device via its mapping. Does not take the superblock lock. | |
164 | */ | |
165 | int sync_blockdev(struct block_device *bdev) | |
166 | { | |
167 | int ret = 0; | |
168 | ||
28fd1298 OH |
169 | if (bdev) |
170 | ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); | |
1da177e4 LT |
171 | return ret; |
172 | } | |
173 | EXPORT_SYMBOL(sync_blockdev); | |
174 | ||
1da177e4 LT |
175 | /* |
176 | * Write out and wait upon all dirty data associated with this | |
177 | * device. Filesystem data as well as the underlying block | |
178 | * device. Takes the superblock lock. | |
179 | */ | |
180 | int fsync_bdev(struct block_device *bdev) | |
181 | { | |
182 | struct super_block *sb = get_super(bdev); | |
183 | if (sb) { | |
184 | int res = fsync_super(sb); | |
185 | drop_super(sb); | |
186 | return res; | |
187 | } | |
188 | return sync_blockdev(bdev); | |
189 | } | |
190 | ||
191 | /** | |
192 | * freeze_bdev -- lock a filesystem and force it into a consistent state | |
193 | * @bdev: blockdevice to lock | |
194 | * | |
f73ca1b7 | 195 | * This takes the block device bd_mount_sem to make sure no new mounts |
1da177e4 LT |
196 | * happen on bdev until thaw_bdev() is called. |
197 | * If a superblock is found on this device, we take the s_umount semaphore | |
198 | * on it to make sure nobody unmounts until the snapshot creation is done. | |
199 | */ | |
200 | struct super_block *freeze_bdev(struct block_device *bdev) | |
201 | { | |
202 | struct super_block *sb; | |
203 | ||
f73ca1b7 | 204 | down(&bdev->bd_mount_sem); |
1da177e4 LT |
205 | sb = get_super(bdev); |
206 | if (sb && !(sb->s_flags & MS_RDONLY)) { | |
207 | sb->s_frozen = SB_FREEZE_WRITE; | |
d59dd462 | 208 | smp_wmb(); |
1da177e4 | 209 | |
d25b9a1f | 210 | __fsync_super(sb); |
1da177e4 LT |
211 | |
212 | sb->s_frozen = SB_FREEZE_TRANS; | |
d59dd462 | 213 | smp_wmb(); |
1da177e4 LT |
214 | |
215 | sync_blockdev(sb->s_bdev); | |
216 | ||
217 | if (sb->s_op->write_super_lockfs) | |
218 | sb->s_op->write_super_lockfs(sb); | |
219 | } | |
220 | ||
221 | sync_blockdev(bdev); | |
222 | return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ | |
223 | } | |
224 | EXPORT_SYMBOL(freeze_bdev); | |
225 | ||
226 | /** | |
227 | * thaw_bdev -- unlock filesystem | |
228 | * @bdev: blockdevice to unlock | |
229 | * @sb: associated superblock | |
230 | * | |
231 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). | |
232 | */ | |
233 | void thaw_bdev(struct block_device *bdev, struct super_block *sb) | |
234 | { | |
235 | if (sb) { | |
236 | BUG_ON(sb->s_bdev != bdev); | |
237 | ||
238 | if (sb->s_op->unlockfs) | |
239 | sb->s_op->unlockfs(sb); | |
240 | sb->s_frozen = SB_UNFROZEN; | |
d59dd462 | 241 | smp_wmb(); |
1da177e4 LT |
242 | wake_up(&sb->s_wait_unfrozen); |
243 | drop_super(sb); | |
244 | } | |
245 | ||
f73ca1b7 | 246 | up(&bdev->bd_mount_sem); |
1da177e4 LT |
247 | } |
248 | EXPORT_SYMBOL(thaw_bdev); | |
249 | ||
1da177e4 LT |
250 | /* |
251 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
252 | * But it's the page lock which protects the buffers. To get around this, | |
253 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
254 | * private_lock. | |
255 | * | |
256 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
257 | * may be quite high. This code could TryLock the page, and if that | |
258 | * succeeds, there is no need to take private_lock. (But if | |
259 | * private_lock is contended then so is mapping->tree_lock). | |
260 | */ | |
261 | static struct buffer_head * | |
385fd4c5 | 262 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
263 | { |
264 | struct inode *bd_inode = bdev->bd_inode; | |
265 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
266 | struct buffer_head *ret = NULL; | |
267 | pgoff_t index; | |
268 | struct buffer_head *bh; | |
269 | struct buffer_head *head; | |
270 | struct page *page; | |
271 | int all_mapped = 1; | |
272 | ||
273 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
274 | page = find_get_page(bd_mapping, index); | |
275 | if (!page) | |
276 | goto out; | |
277 | ||
278 | spin_lock(&bd_mapping->private_lock); | |
279 | if (!page_has_buffers(page)) | |
280 | goto out_unlock; | |
281 | head = page_buffers(page); | |
282 | bh = head; | |
283 | do { | |
284 | if (bh->b_blocknr == block) { | |
285 | ret = bh; | |
286 | get_bh(bh); | |
287 | goto out_unlock; | |
288 | } | |
289 | if (!buffer_mapped(bh)) | |
290 | all_mapped = 0; | |
291 | bh = bh->b_this_page; | |
292 | } while (bh != head); | |
293 | ||
294 | /* we might be here because some of the buffers on this page are | |
295 | * not mapped. This is due to various races between | |
296 | * file io on the block device and getblk. It gets dealt with | |
297 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
298 | */ | |
299 | if (all_mapped) { | |
300 | printk("__find_get_block_slow() failed. " | |
301 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
302 | (unsigned long long)block, |
303 | (unsigned long long)bh->b_blocknr); | |
304 | printk("b_state=0x%08lx, b_size=%zu\n", | |
305 | bh->b_state, bh->b_size); | |
1da177e4 LT |
306 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
307 | } | |
308 | out_unlock: | |
309 | spin_unlock(&bd_mapping->private_lock); | |
310 | page_cache_release(page); | |
311 | out: | |
312 | return ret; | |
313 | } | |
314 | ||
315 | /* If invalidate_buffers() will trash dirty buffers, it means some kind | |
316 | of fs corruption is going on. Trashing dirty data always imply losing | |
317 | information that was supposed to be just stored on the physical layer | |
318 | by the user. | |
319 | ||
320 | Thus invalidate_buffers in general usage is not allwowed to trash | |
321 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to | |
322 | be preserved. These buffers are simply skipped. | |
323 | ||
324 | We also skip buffers which are still in use. For example this can | |
325 | happen if a userspace program is reading the block device. | |
326 | ||
327 | NOTE: In the case where the user removed a removable-media-disk even if | |
328 | there's still dirty data not synced on disk (due a bug in the device driver | |
329 | or due an error of the user), by not destroying the dirty buffers we could | |
330 | generate corruption also on the next media inserted, thus a parameter is | |
331 | necessary to handle this case in the most safe way possible (trying | |
332 | to not corrupt also the new disk inserted with the data belonging to | |
333 | the old now corrupted disk). Also for the ramdisk the natural thing | |
334 | to do in order to release the ramdisk memory is to destroy dirty buffers. | |
335 | ||
336 | These are two special cases. Normal usage imply the device driver | |
337 | to issue a sync on the device (without waiting I/O completion) and | |
338 | then an invalidate_buffers call that doesn't trash dirty buffers. | |
339 | ||
340 | For handling cache coherency with the blkdev pagecache the 'update' case | |
341 | is been introduced. It is needed to re-read from disk any pinned | |
342 | buffer. NOTE: re-reading from disk is destructive so we can do it only | |
343 | when we assume nobody is changing the buffercache under our I/O and when | |
344 | we think the disk contains more recent information than the buffercache. | |
345 | The update == 1 pass marks the buffers we need to update, the update == 2 | |
346 | pass does the actual I/O. */ | |
f98393a6 | 347 | void invalidate_bdev(struct block_device *bdev) |
1da177e4 | 348 | { |
0e1dfc66 AM |
349 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
350 | ||
351 | if (mapping->nrpages == 0) | |
352 | return; | |
353 | ||
1da177e4 | 354 | invalidate_bh_lrus(); |
fc0ecff6 | 355 | invalidate_mapping_pages(mapping, 0, -1); |
1da177e4 LT |
356 | } |
357 | ||
358 | /* | |
359 | * Kick pdflush then try to free up some ZONE_NORMAL memory. | |
360 | */ | |
361 | static void free_more_memory(void) | |
362 | { | |
363 | struct zone **zones; | |
364 | pg_data_t *pgdat; | |
365 | ||
687a21ce | 366 | wakeup_pdflush(1024); |
1da177e4 LT |
367 | yield(); |
368 | ||
ec936fc5 | 369 | for_each_online_pgdat(pgdat) { |
af4ca457 | 370 | zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones; |
1da177e4 | 371 | if (*zones) |
5ad333eb | 372 | try_to_free_pages(zones, 0, GFP_NOFS); |
1da177e4 LT |
373 | } |
374 | } | |
375 | ||
376 | /* | |
377 | * I/O completion handler for block_read_full_page() - pages | |
378 | * which come unlocked at the end of I/O. | |
379 | */ | |
380 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
381 | { | |
1da177e4 | 382 | unsigned long flags; |
a3972203 | 383 | struct buffer_head *first; |
1da177e4 LT |
384 | struct buffer_head *tmp; |
385 | struct page *page; | |
386 | int page_uptodate = 1; | |
387 | ||
388 | BUG_ON(!buffer_async_read(bh)); | |
389 | ||
390 | page = bh->b_page; | |
391 | if (uptodate) { | |
392 | set_buffer_uptodate(bh); | |
393 | } else { | |
394 | clear_buffer_uptodate(bh); | |
395 | if (printk_ratelimit()) | |
396 | buffer_io_error(bh); | |
397 | SetPageError(page); | |
398 | } | |
399 | ||
400 | /* | |
401 | * Be _very_ careful from here on. Bad things can happen if | |
402 | * two buffer heads end IO at almost the same time and both | |
403 | * decide that the page is now completely done. | |
404 | */ | |
a3972203 NP |
405 | first = page_buffers(page); |
406 | local_irq_save(flags); | |
407 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
408 | clear_buffer_async_read(bh); |
409 | unlock_buffer(bh); | |
410 | tmp = bh; | |
411 | do { | |
412 | if (!buffer_uptodate(tmp)) | |
413 | page_uptodate = 0; | |
414 | if (buffer_async_read(tmp)) { | |
415 | BUG_ON(!buffer_locked(tmp)); | |
416 | goto still_busy; | |
417 | } | |
418 | tmp = tmp->b_this_page; | |
419 | } while (tmp != bh); | |
a3972203 NP |
420 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
421 | local_irq_restore(flags); | |
1da177e4 LT |
422 | |
423 | /* | |
424 | * If none of the buffers had errors and they are all | |
425 | * uptodate then we can set the page uptodate. | |
426 | */ | |
427 | if (page_uptodate && !PageError(page)) | |
428 | SetPageUptodate(page); | |
429 | unlock_page(page); | |
430 | return; | |
431 | ||
432 | still_busy: | |
a3972203 NP |
433 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
434 | local_irq_restore(flags); | |
1da177e4 LT |
435 | return; |
436 | } | |
437 | ||
438 | /* | |
439 | * Completion handler for block_write_full_page() - pages which are unlocked | |
440 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
441 | */ | |
b6cd0b77 | 442 | static void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
443 | { |
444 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 445 | unsigned long flags; |
a3972203 | 446 | struct buffer_head *first; |
1da177e4 LT |
447 | struct buffer_head *tmp; |
448 | struct page *page; | |
449 | ||
450 | BUG_ON(!buffer_async_write(bh)); | |
451 | ||
452 | page = bh->b_page; | |
453 | if (uptodate) { | |
454 | set_buffer_uptodate(bh); | |
455 | } else { | |
456 | if (printk_ratelimit()) { | |
457 | buffer_io_error(bh); | |
458 | printk(KERN_WARNING "lost page write due to " | |
459 | "I/O error on %s\n", | |
460 | bdevname(bh->b_bdev, b)); | |
461 | } | |
462 | set_bit(AS_EIO, &page->mapping->flags); | |
58ff407b | 463 | set_buffer_write_io_error(bh); |
1da177e4 LT |
464 | clear_buffer_uptodate(bh); |
465 | SetPageError(page); | |
466 | } | |
467 | ||
a3972203 NP |
468 | first = page_buffers(page); |
469 | local_irq_save(flags); | |
470 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
471 | ||
1da177e4 LT |
472 | clear_buffer_async_write(bh); |
473 | unlock_buffer(bh); | |
474 | tmp = bh->b_this_page; | |
475 | while (tmp != bh) { | |
476 | if (buffer_async_write(tmp)) { | |
477 | BUG_ON(!buffer_locked(tmp)); | |
478 | goto still_busy; | |
479 | } | |
480 | tmp = tmp->b_this_page; | |
481 | } | |
a3972203 NP |
482 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
483 | local_irq_restore(flags); | |
1da177e4 LT |
484 | end_page_writeback(page); |
485 | return; | |
486 | ||
487 | still_busy: | |
a3972203 NP |
488 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
489 | local_irq_restore(flags); | |
1da177e4 LT |
490 | return; |
491 | } | |
492 | ||
493 | /* | |
494 | * If a page's buffers are under async readin (end_buffer_async_read | |
495 | * completion) then there is a possibility that another thread of | |
496 | * control could lock one of the buffers after it has completed | |
497 | * but while some of the other buffers have not completed. This | |
498 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
499 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
500 | * that this buffer is not under async I/O. | |
501 | * | |
502 | * The page comes unlocked when it has no locked buffer_async buffers | |
503 | * left. | |
504 | * | |
505 | * PageLocked prevents anyone starting new async I/O reads any of | |
506 | * the buffers. | |
507 | * | |
508 | * PageWriteback is used to prevent simultaneous writeout of the same | |
509 | * page. | |
510 | * | |
511 | * PageLocked prevents anyone from starting writeback of a page which is | |
512 | * under read I/O (PageWriteback is only ever set against a locked page). | |
513 | */ | |
514 | static void mark_buffer_async_read(struct buffer_head *bh) | |
515 | { | |
516 | bh->b_end_io = end_buffer_async_read; | |
517 | set_buffer_async_read(bh); | |
518 | } | |
519 | ||
520 | void mark_buffer_async_write(struct buffer_head *bh) | |
521 | { | |
522 | bh->b_end_io = end_buffer_async_write; | |
523 | set_buffer_async_write(bh); | |
524 | } | |
525 | EXPORT_SYMBOL(mark_buffer_async_write); | |
526 | ||
527 | ||
528 | /* | |
529 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
530 | * fsync functions. A common requirement for buffer-based filesystems is | |
531 | * that certain data from the backing blockdev needs to be written out for | |
532 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
533 | * written back and waited upon before fsync() returns. | |
534 | * | |
535 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
536 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
537 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
538 | * | |
539 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
540 | * from their controlling inode's queue when they are being freed. But | |
541 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
542 | * at the time, not against the S_ISREG file which depends on those buffers. | |
543 | * So the locking for private_list is via the private_lock in the address_space | |
544 | * which backs the buffers. Which is different from the address_space | |
545 | * against which the buffers are listed. So for a particular address_space, | |
546 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
547 | * mapping->private_list will always be protected by the backing blockdev's | |
548 | * ->private_lock. | |
549 | * | |
550 | * Which introduces a requirement: all buffers on an address_space's | |
551 | * ->private_list must be from the same address_space: the blockdev's. | |
552 | * | |
553 | * address_spaces which do not place buffers at ->private_list via these | |
554 | * utility functions are free to use private_lock and private_list for | |
555 | * whatever they want. The only requirement is that list_empty(private_list) | |
556 | * be true at clear_inode() time. | |
557 | * | |
558 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
559 | * filesystems should do that. invalidate_inode_buffers() should just go | |
560 | * BUG_ON(!list_empty). | |
561 | * | |
562 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
563 | * take an address_space, not an inode. And it should be called | |
564 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
565 | * queued up. | |
566 | * | |
567 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
568 | * list if it is already on a list. Because if the buffer is on a list, | |
569 | * it *must* already be on the right one. If not, the filesystem is being | |
570 | * silly. This will save a ton of locking. But first we have to ensure | |
571 | * that buffers are taken *off* the old inode's list when they are freed | |
572 | * (presumably in truncate). That requires careful auditing of all | |
573 | * filesystems (do it inside bforget()). It could also be done by bringing | |
574 | * b_inode back. | |
575 | */ | |
576 | ||
577 | /* | |
578 | * The buffer's backing address_space's private_lock must be held | |
579 | */ | |
580 | static inline void __remove_assoc_queue(struct buffer_head *bh) | |
581 | { | |
582 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b JK |
583 | WARN_ON(!bh->b_assoc_map); |
584 | if (buffer_write_io_error(bh)) | |
585 | set_bit(AS_EIO, &bh->b_assoc_map->flags); | |
586 | bh->b_assoc_map = NULL; | |
1da177e4 LT |
587 | } |
588 | ||
589 | int inode_has_buffers(struct inode *inode) | |
590 | { | |
591 | return !list_empty(&inode->i_data.private_list); | |
592 | } | |
593 | ||
594 | /* | |
595 | * osync is designed to support O_SYNC io. It waits synchronously for | |
596 | * all already-submitted IO to complete, but does not queue any new | |
597 | * writes to the disk. | |
598 | * | |
599 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
600 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
601 | * completion. Any other dirty buffers which are not yet queued for | |
602 | * write will not be flushed to disk by the osync. | |
603 | */ | |
604 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
605 | { | |
606 | struct buffer_head *bh; | |
607 | struct list_head *p; | |
608 | int err = 0; | |
609 | ||
610 | spin_lock(lock); | |
611 | repeat: | |
612 | list_for_each_prev(p, list) { | |
613 | bh = BH_ENTRY(p); | |
614 | if (buffer_locked(bh)) { | |
615 | get_bh(bh); | |
616 | spin_unlock(lock); | |
617 | wait_on_buffer(bh); | |
618 | if (!buffer_uptodate(bh)) | |
619 | err = -EIO; | |
620 | brelse(bh); | |
621 | spin_lock(lock); | |
622 | goto repeat; | |
623 | } | |
624 | } | |
625 | spin_unlock(lock); | |
626 | return err; | |
627 | } | |
628 | ||
629 | /** | |
630 | * sync_mapping_buffers - write out and wait upon a mapping's "associated" | |
631 | * buffers | |
67be2dd1 | 632 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
633 | * |
634 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
635 | * that I/O. | |
636 | * | |
67be2dd1 MW |
637 | * Basically, this is a convenience function for fsync(). |
638 | * @mapping is a file or directory which needs those buffers to be written for | |
639 | * a successful fsync(). | |
1da177e4 LT |
640 | */ |
641 | int sync_mapping_buffers(struct address_space *mapping) | |
642 | { | |
643 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
644 | ||
645 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
646 | return 0; | |
647 | ||
648 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
649 | &mapping->private_list); | |
650 | } | |
651 | EXPORT_SYMBOL(sync_mapping_buffers); | |
652 | ||
653 | /* | |
654 | * Called when we've recently written block `bblock', and it is known that | |
655 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
656 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
657 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
658 | */ | |
659 | void write_boundary_block(struct block_device *bdev, | |
660 | sector_t bblock, unsigned blocksize) | |
661 | { | |
662 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
663 | if (bh) { | |
664 | if (buffer_dirty(bh)) | |
665 | ll_rw_block(WRITE, 1, &bh); | |
666 | put_bh(bh); | |
667 | } | |
668 | } | |
669 | ||
670 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
671 | { | |
672 | struct address_space *mapping = inode->i_mapping; | |
673 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
674 | ||
675 | mark_buffer_dirty(bh); | |
676 | if (!mapping->assoc_mapping) { | |
677 | mapping->assoc_mapping = buffer_mapping; | |
678 | } else { | |
e827f923 | 679 | BUG_ON(mapping->assoc_mapping != buffer_mapping); |
1da177e4 LT |
680 | } |
681 | if (list_empty(&bh->b_assoc_buffers)) { | |
682 | spin_lock(&buffer_mapping->private_lock); | |
683 | list_move_tail(&bh->b_assoc_buffers, | |
684 | &mapping->private_list); | |
58ff407b | 685 | bh->b_assoc_map = mapping; |
1da177e4 LT |
686 | spin_unlock(&buffer_mapping->private_lock); |
687 | } | |
688 | } | |
689 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
690 | ||
787d2214 NP |
691 | /* |
692 | * Mark the page dirty, and set it dirty in the radix tree, and mark the inode | |
693 | * dirty. | |
694 | * | |
695 | * If warn is true, then emit a warning if the page is not uptodate and has | |
696 | * not been truncated. | |
697 | */ | |
698 | static int __set_page_dirty(struct page *page, | |
699 | struct address_space *mapping, int warn) | |
700 | { | |
701 | if (unlikely(!mapping)) | |
702 | return !TestSetPageDirty(page); | |
703 | ||
704 | if (TestSetPageDirty(page)) | |
705 | return 0; | |
706 | ||
707 | write_lock_irq(&mapping->tree_lock); | |
708 | if (page->mapping) { /* Race with truncate? */ | |
709 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
710 | ||
711 | if (mapping_cap_account_dirty(mapping)) { | |
712 | __inc_zone_page_state(page, NR_FILE_DIRTY); | |
c9e51e41 PZ |
713 | __inc_bdi_stat(mapping->backing_dev_info, |
714 | BDI_RECLAIMABLE); | |
787d2214 NP |
715 | task_io_account_write(PAGE_CACHE_SIZE); |
716 | } | |
717 | radix_tree_tag_set(&mapping->page_tree, | |
718 | page_index(page), PAGECACHE_TAG_DIRTY); | |
719 | } | |
720 | write_unlock_irq(&mapping->tree_lock); | |
721 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
722 | ||
723 | return 1; | |
724 | } | |
725 | ||
1da177e4 LT |
726 | /* |
727 | * Add a page to the dirty page list. | |
728 | * | |
729 | * It is a sad fact of life that this function is called from several places | |
730 | * deeply under spinlocking. It may not sleep. | |
731 | * | |
732 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
733 | * dirty-state coherency between the page and the buffers. It the page does | |
734 | * not have buffers then when they are later attached they will all be set | |
735 | * dirty. | |
736 | * | |
737 | * The buffers are dirtied before the page is dirtied. There's a small race | |
738 | * window in which a writepage caller may see the page cleanness but not the | |
739 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
740 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
741 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
742 | * page on the dirty page list. | |
743 | * | |
744 | * We use private_lock to lock against try_to_free_buffers while using the | |
745 | * page's buffer list. Also use this to protect against clean buffers being | |
746 | * added to the page after it was set dirty. | |
747 | * | |
748 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
749 | * address_space though. | |
750 | */ | |
751 | int __set_page_dirty_buffers(struct page *page) | |
752 | { | |
787d2214 | 753 | struct address_space *mapping = page_mapping(page); |
ebf7a227 NP |
754 | |
755 | if (unlikely(!mapping)) | |
756 | return !TestSetPageDirty(page); | |
1da177e4 LT |
757 | |
758 | spin_lock(&mapping->private_lock); | |
759 | if (page_has_buffers(page)) { | |
760 | struct buffer_head *head = page_buffers(page); | |
761 | struct buffer_head *bh = head; | |
762 | ||
763 | do { | |
764 | set_buffer_dirty(bh); | |
765 | bh = bh->b_this_page; | |
766 | } while (bh != head); | |
767 | } | |
768 | spin_unlock(&mapping->private_lock); | |
769 | ||
787d2214 | 770 | return __set_page_dirty(page, mapping, 1); |
1da177e4 LT |
771 | } |
772 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
773 | ||
774 | /* | |
775 | * Write out and wait upon a list of buffers. | |
776 | * | |
777 | * We have conflicting pressures: we want to make sure that all | |
778 | * initially dirty buffers get waited on, but that any subsequently | |
779 | * dirtied buffers don't. After all, we don't want fsync to last | |
780 | * forever if somebody is actively writing to the file. | |
781 | * | |
782 | * Do this in two main stages: first we copy dirty buffers to a | |
783 | * temporary inode list, queueing the writes as we go. Then we clean | |
784 | * up, waiting for those writes to complete. | |
785 | * | |
786 | * During this second stage, any subsequent updates to the file may end | |
787 | * up refiling the buffer on the original inode's dirty list again, so | |
788 | * there is a chance we will end up with a buffer queued for write but | |
789 | * not yet completed on that list. So, as a final cleanup we go through | |
790 | * the osync code to catch these locked, dirty buffers without requeuing | |
791 | * any newly dirty buffers for write. | |
792 | */ | |
793 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
794 | { | |
795 | struct buffer_head *bh; | |
796 | struct list_head tmp; | |
797 | int err = 0, err2; | |
798 | ||
799 | INIT_LIST_HEAD(&tmp); | |
800 | ||
801 | spin_lock(lock); | |
802 | while (!list_empty(list)) { | |
803 | bh = BH_ENTRY(list->next); | |
58ff407b | 804 | __remove_assoc_queue(bh); |
1da177e4 LT |
805 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
806 | list_add(&bh->b_assoc_buffers, &tmp); | |
807 | if (buffer_dirty(bh)) { | |
808 | get_bh(bh); | |
809 | spin_unlock(lock); | |
810 | /* | |
811 | * Ensure any pending I/O completes so that | |
812 | * ll_rw_block() actually writes the current | |
813 | * contents - it is a noop if I/O is still in | |
814 | * flight on potentially older contents. | |
815 | */ | |
a7662236 | 816 | ll_rw_block(SWRITE, 1, &bh); |
1da177e4 LT |
817 | brelse(bh); |
818 | spin_lock(lock); | |
819 | } | |
820 | } | |
821 | } | |
822 | ||
823 | while (!list_empty(&tmp)) { | |
824 | bh = BH_ENTRY(tmp.prev); | |
58ff407b | 825 | list_del_init(&bh->b_assoc_buffers); |
1da177e4 LT |
826 | get_bh(bh); |
827 | spin_unlock(lock); | |
828 | wait_on_buffer(bh); | |
829 | if (!buffer_uptodate(bh)) | |
830 | err = -EIO; | |
831 | brelse(bh); | |
832 | spin_lock(lock); | |
833 | } | |
834 | ||
835 | spin_unlock(lock); | |
836 | err2 = osync_buffers_list(lock, list); | |
837 | if (err) | |
838 | return err; | |
839 | else | |
840 | return err2; | |
841 | } | |
842 | ||
843 | /* | |
844 | * Invalidate any and all dirty buffers on a given inode. We are | |
845 | * probably unmounting the fs, but that doesn't mean we have already | |
846 | * done a sync(). Just drop the buffers from the inode list. | |
847 | * | |
848 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
849 | * assumes that all the buffers are against the blockdev. Not true | |
850 | * for reiserfs. | |
851 | */ | |
852 | void invalidate_inode_buffers(struct inode *inode) | |
853 | { | |
854 | if (inode_has_buffers(inode)) { | |
855 | struct address_space *mapping = &inode->i_data; | |
856 | struct list_head *list = &mapping->private_list; | |
857 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
858 | ||
859 | spin_lock(&buffer_mapping->private_lock); | |
860 | while (!list_empty(list)) | |
861 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
862 | spin_unlock(&buffer_mapping->private_lock); | |
863 | } | |
864 | } | |
865 | ||
866 | /* | |
867 | * Remove any clean buffers from the inode's buffer list. This is called | |
868 | * when we're trying to free the inode itself. Those buffers can pin it. | |
869 | * | |
870 | * Returns true if all buffers were removed. | |
871 | */ | |
872 | int remove_inode_buffers(struct inode *inode) | |
873 | { | |
874 | int ret = 1; | |
875 | ||
876 | if (inode_has_buffers(inode)) { | |
877 | struct address_space *mapping = &inode->i_data; | |
878 | struct list_head *list = &mapping->private_list; | |
879 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
880 | ||
881 | spin_lock(&buffer_mapping->private_lock); | |
882 | while (!list_empty(list)) { | |
883 | struct buffer_head *bh = BH_ENTRY(list->next); | |
884 | if (buffer_dirty(bh)) { | |
885 | ret = 0; | |
886 | break; | |
887 | } | |
888 | __remove_assoc_queue(bh); | |
889 | } | |
890 | spin_unlock(&buffer_mapping->private_lock); | |
891 | } | |
892 | return ret; | |
893 | } | |
894 | ||
895 | /* | |
896 | * Create the appropriate buffers when given a page for data area and | |
897 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
898 | * follow the buffers created. Return NULL if unable to create more | |
899 | * buffers. | |
900 | * | |
901 | * The retry flag is used to differentiate async IO (paging, swapping) | |
902 | * which may not fail from ordinary buffer allocations. | |
903 | */ | |
904 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
905 | int retry) | |
906 | { | |
907 | struct buffer_head *bh, *head; | |
908 | long offset; | |
909 | ||
910 | try_again: | |
911 | head = NULL; | |
912 | offset = PAGE_SIZE; | |
913 | while ((offset -= size) >= 0) { | |
914 | bh = alloc_buffer_head(GFP_NOFS); | |
915 | if (!bh) | |
916 | goto no_grow; | |
917 | ||
918 | bh->b_bdev = NULL; | |
919 | bh->b_this_page = head; | |
920 | bh->b_blocknr = -1; | |
921 | head = bh; | |
922 | ||
923 | bh->b_state = 0; | |
924 | atomic_set(&bh->b_count, 0); | |
fc5cd582 | 925 | bh->b_private = NULL; |
1da177e4 LT |
926 | bh->b_size = size; |
927 | ||
928 | /* Link the buffer to its page */ | |
929 | set_bh_page(bh, page, offset); | |
930 | ||
01ffe339 | 931 | init_buffer(bh, NULL, NULL); |
1da177e4 LT |
932 | } |
933 | return head; | |
934 | /* | |
935 | * In case anything failed, we just free everything we got. | |
936 | */ | |
937 | no_grow: | |
938 | if (head) { | |
939 | do { | |
940 | bh = head; | |
941 | head = head->b_this_page; | |
942 | free_buffer_head(bh); | |
943 | } while (head); | |
944 | } | |
945 | ||
946 | /* | |
947 | * Return failure for non-async IO requests. Async IO requests | |
948 | * are not allowed to fail, so we have to wait until buffer heads | |
949 | * become available. But we don't want tasks sleeping with | |
950 | * partially complete buffers, so all were released above. | |
951 | */ | |
952 | if (!retry) | |
953 | return NULL; | |
954 | ||
955 | /* We're _really_ low on memory. Now we just | |
956 | * wait for old buffer heads to become free due to | |
957 | * finishing IO. Since this is an async request and | |
958 | * the reserve list is empty, we're sure there are | |
959 | * async buffer heads in use. | |
960 | */ | |
961 | free_more_memory(); | |
962 | goto try_again; | |
963 | } | |
964 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
965 | ||
966 | static inline void | |
967 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
968 | { | |
969 | struct buffer_head *bh, *tail; | |
970 | ||
971 | bh = head; | |
972 | do { | |
973 | tail = bh; | |
974 | bh = bh->b_this_page; | |
975 | } while (bh); | |
976 | tail->b_this_page = head; | |
977 | attach_page_buffers(page, head); | |
978 | } | |
979 | ||
980 | /* | |
981 | * Initialise the state of a blockdev page's buffers. | |
982 | */ | |
983 | static void | |
984 | init_page_buffers(struct page *page, struct block_device *bdev, | |
985 | sector_t block, int size) | |
986 | { | |
987 | struct buffer_head *head = page_buffers(page); | |
988 | struct buffer_head *bh = head; | |
989 | int uptodate = PageUptodate(page); | |
990 | ||
991 | do { | |
992 | if (!buffer_mapped(bh)) { | |
993 | init_buffer(bh, NULL, NULL); | |
994 | bh->b_bdev = bdev; | |
995 | bh->b_blocknr = block; | |
996 | if (uptodate) | |
997 | set_buffer_uptodate(bh); | |
998 | set_buffer_mapped(bh); | |
999 | } | |
1000 | block++; | |
1001 | bh = bh->b_this_page; | |
1002 | } while (bh != head); | |
1003 | } | |
1004 | ||
1005 | /* | |
1006 | * Create the page-cache page that contains the requested block. | |
1007 | * | |
1008 | * This is user purely for blockdev mappings. | |
1009 | */ | |
1010 | static struct page * | |
1011 | grow_dev_page(struct block_device *bdev, sector_t block, | |
1012 | pgoff_t index, int size) | |
1013 | { | |
1014 | struct inode *inode = bdev->bd_inode; | |
1015 | struct page *page; | |
1016 | struct buffer_head *bh; | |
1017 | ||
ea125892 | 1018 | page = find_or_create_page(inode->i_mapping, index, |
769848c0 | 1019 | (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); |
1da177e4 LT |
1020 | if (!page) |
1021 | return NULL; | |
1022 | ||
e827f923 | 1023 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
1024 | |
1025 | if (page_has_buffers(page)) { | |
1026 | bh = page_buffers(page); | |
1027 | if (bh->b_size == size) { | |
1028 | init_page_buffers(page, bdev, block, size); | |
1029 | return page; | |
1030 | } | |
1031 | if (!try_to_free_buffers(page)) | |
1032 | goto failed; | |
1033 | } | |
1034 | ||
1035 | /* | |
1036 | * Allocate some buffers for this page | |
1037 | */ | |
1038 | bh = alloc_page_buffers(page, size, 0); | |
1039 | if (!bh) | |
1040 | goto failed; | |
1041 | ||
1042 | /* | |
1043 | * Link the page to the buffers and initialise them. Take the | |
1044 | * lock to be atomic wrt __find_get_block(), which does not | |
1045 | * run under the page lock. | |
1046 | */ | |
1047 | spin_lock(&inode->i_mapping->private_lock); | |
1048 | link_dev_buffers(page, bh); | |
1049 | init_page_buffers(page, bdev, block, size); | |
1050 | spin_unlock(&inode->i_mapping->private_lock); | |
1051 | return page; | |
1052 | ||
1053 | failed: | |
1054 | BUG(); | |
1055 | unlock_page(page); | |
1056 | page_cache_release(page); | |
1057 | return NULL; | |
1058 | } | |
1059 | ||
1060 | /* | |
1061 | * Create buffers for the specified block device block's page. If | |
1062 | * that page was dirty, the buffers are set dirty also. | |
1da177e4 | 1063 | */ |
858119e1 | 1064 | static int |
1da177e4 LT |
1065 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1066 | { | |
1067 | struct page *page; | |
1068 | pgoff_t index; | |
1069 | int sizebits; | |
1070 | ||
1071 | sizebits = -1; | |
1072 | do { | |
1073 | sizebits++; | |
1074 | } while ((size << sizebits) < PAGE_SIZE); | |
1075 | ||
1076 | index = block >> sizebits; | |
1da177e4 | 1077 | |
e5657933 AM |
1078 | /* |
1079 | * Check for a block which wants to lie outside our maximum possible | |
1080 | * pagecache index. (this comparison is done using sector_t types). | |
1081 | */ | |
1082 | if (unlikely(index != block >> sizebits)) { | |
1083 | char b[BDEVNAME_SIZE]; | |
1084 | ||
1085 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1086 | "device %s\n", | |
1087 | __FUNCTION__, (unsigned long long)block, | |
1088 | bdevname(bdev, b)); | |
1089 | return -EIO; | |
1090 | } | |
1091 | block = index << sizebits; | |
1da177e4 LT |
1092 | /* Create a page with the proper size buffers.. */ |
1093 | page = grow_dev_page(bdev, block, index, size); | |
1094 | if (!page) | |
1095 | return 0; | |
1096 | unlock_page(page); | |
1097 | page_cache_release(page); | |
1098 | return 1; | |
1099 | } | |
1100 | ||
75c96f85 | 1101 | static struct buffer_head * |
1da177e4 LT |
1102 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1103 | { | |
1104 | /* Size must be multiple of hard sectorsize */ | |
1105 | if (unlikely(size & (bdev_hardsect_size(bdev)-1) || | |
1106 | (size < 512 || size > PAGE_SIZE))) { | |
1107 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1108 | size); | |
1109 | printk(KERN_ERR "hardsect size: %d\n", | |
1110 | bdev_hardsect_size(bdev)); | |
1111 | ||
1112 | dump_stack(); | |
1113 | return NULL; | |
1114 | } | |
1115 | ||
1116 | for (;;) { | |
1117 | struct buffer_head * bh; | |
e5657933 | 1118 | int ret; |
1da177e4 LT |
1119 | |
1120 | bh = __find_get_block(bdev, block, size); | |
1121 | if (bh) | |
1122 | return bh; | |
1123 | ||
e5657933 AM |
1124 | ret = grow_buffers(bdev, block, size); |
1125 | if (ret < 0) | |
1126 | return NULL; | |
1127 | if (ret == 0) | |
1da177e4 LT |
1128 | free_more_memory(); |
1129 | } | |
1130 | } | |
1131 | ||
1132 | /* | |
1133 | * The relationship between dirty buffers and dirty pages: | |
1134 | * | |
1135 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1136 | * the page is tagged dirty in its radix tree. | |
1137 | * | |
1138 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1139 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1140 | * merely a hint about the true dirty state. | |
1141 | * | |
1142 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1143 | * (if the page has buffers). | |
1144 | * | |
1145 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1146 | * buffers are not. | |
1147 | * | |
1148 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1149 | * individually become uptodate. But their backing page remains not | |
1150 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1151 | * block_read_full_page() against that page will discover all the uptodate | |
1152 | * buffers, will set the page uptodate and will perform no I/O. | |
1153 | */ | |
1154 | ||
1155 | /** | |
1156 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1157 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1158 | * |
1159 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1160 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1161 | * tree and then attach the address_space's inode to its superblock's dirty | |
1162 | * inode list. | |
1163 | * | |
1164 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
1165 | * mapping->tree_lock and the global inode_lock. | |
1166 | */ | |
1167 | void fastcall mark_buffer_dirty(struct buffer_head *bh) | |
1168 | { | |
787d2214 | 1169 | WARN_ON_ONCE(!buffer_uptodate(bh)); |
1da177e4 | 1170 | if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) |
787d2214 | 1171 | __set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0); |
1da177e4 LT |
1172 | } |
1173 | ||
1174 | /* | |
1175 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1176 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1177 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1178 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1179 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1180 | */ | |
1181 | void __brelse(struct buffer_head * buf) | |
1182 | { | |
1183 | if (atomic_read(&buf->b_count)) { | |
1184 | put_bh(buf); | |
1185 | return; | |
1186 | } | |
1187 | printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); | |
1188 | WARN_ON(1); | |
1189 | } | |
1190 | ||
1191 | /* | |
1192 | * bforget() is like brelse(), except it discards any | |
1193 | * potentially dirty data. | |
1194 | */ | |
1195 | void __bforget(struct buffer_head *bh) | |
1196 | { | |
1197 | clear_buffer_dirty(bh); | |
1198 | if (!list_empty(&bh->b_assoc_buffers)) { | |
1199 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
1200 | ||
1201 | spin_lock(&buffer_mapping->private_lock); | |
1202 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 1203 | bh->b_assoc_map = NULL; |
1da177e4 LT |
1204 | spin_unlock(&buffer_mapping->private_lock); |
1205 | } | |
1206 | __brelse(bh); | |
1207 | } | |
1208 | ||
1209 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1210 | { | |
1211 | lock_buffer(bh); | |
1212 | if (buffer_uptodate(bh)) { | |
1213 | unlock_buffer(bh); | |
1214 | return bh; | |
1215 | } else { | |
1216 | get_bh(bh); | |
1217 | bh->b_end_io = end_buffer_read_sync; | |
1218 | submit_bh(READ, bh); | |
1219 | wait_on_buffer(bh); | |
1220 | if (buffer_uptodate(bh)) | |
1221 | return bh; | |
1222 | } | |
1223 | brelse(bh); | |
1224 | return NULL; | |
1225 | } | |
1226 | ||
1227 | /* | |
1228 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1229 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1230 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1231 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1232 | * CPU's LRUs at the same time. | |
1233 | * | |
1234 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1235 | * sb_find_get_block(). | |
1236 | * | |
1237 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1238 | * a local interrupt disable for that. | |
1239 | */ | |
1240 | ||
1241 | #define BH_LRU_SIZE 8 | |
1242 | ||
1243 | struct bh_lru { | |
1244 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1245 | }; | |
1246 | ||
1247 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1248 | ||
1249 | #ifdef CONFIG_SMP | |
1250 | #define bh_lru_lock() local_irq_disable() | |
1251 | #define bh_lru_unlock() local_irq_enable() | |
1252 | #else | |
1253 | #define bh_lru_lock() preempt_disable() | |
1254 | #define bh_lru_unlock() preempt_enable() | |
1255 | #endif | |
1256 | ||
1257 | static inline void check_irqs_on(void) | |
1258 | { | |
1259 | #ifdef irqs_disabled | |
1260 | BUG_ON(irqs_disabled()); | |
1261 | #endif | |
1262 | } | |
1263 | ||
1264 | /* | |
1265 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1266 | */ | |
1267 | static void bh_lru_install(struct buffer_head *bh) | |
1268 | { | |
1269 | struct buffer_head *evictee = NULL; | |
1270 | struct bh_lru *lru; | |
1271 | ||
1272 | check_irqs_on(); | |
1273 | bh_lru_lock(); | |
1274 | lru = &__get_cpu_var(bh_lrus); | |
1275 | if (lru->bhs[0] != bh) { | |
1276 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1277 | int in; | |
1278 | int out = 0; | |
1279 | ||
1280 | get_bh(bh); | |
1281 | bhs[out++] = bh; | |
1282 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
1283 | struct buffer_head *bh2 = lru->bhs[in]; | |
1284 | ||
1285 | if (bh2 == bh) { | |
1286 | __brelse(bh2); | |
1287 | } else { | |
1288 | if (out >= BH_LRU_SIZE) { | |
1289 | BUG_ON(evictee != NULL); | |
1290 | evictee = bh2; | |
1291 | } else { | |
1292 | bhs[out++] = bh2; | |
1293 | } | |
1294 | } | |
1295 | } | |
1296 | while (out < BH_LRU_SIZE) | |
1297 | bhs[out++] = NULL; | |
1298 | memcpy(lru->bhs, bhs, sizeof(bhs)); | |
1299 | } | |
1300 | bh_lru_unlock(); | |
1301 | ||
1302 | if (evictee) | |
1303 | __brelse(evictee); | |
1304 | } | |
1305 | ||
1306 | /* | |
1307 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1308 | */ | |
858119e1 | 1309 | static struct buffer_head * |
3991d3bd | 1310 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1311 | { |
1312 | struct buffer_head *ret = NULL; | |
1313 | struct bh_lru *lru; | |
3991d3bd | 1314 | unsigned int i; |
1da177e4 LT |
1315 | |
1316 | check_irqs_on(); | |
1317 | bh_lru_lock(); | |
1318 | lru = &__get_cpu_var(bh_lrus); | |
1319 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1320 | struct buffer_head *bh = lru->bhs[i]; | |
1321 | ||
1322 | if (bh && bh->b_bdev == bdev && | |
1323 | bh->b_blocknr == block && bh->b_size == size) { | |
1324 | if (i) { | |
1325 | while (i) { | |
1326 | lru->bhs[i] = lru->bhs[i - 1]; | |
1327 | i--; | |
1328 | } | |
1329 | lru->bhs[0] = bh; | |
1330 | } | |
1331 | get_bh(bh); | |
1332 | ret = bh; | |
1333 | break; | |
1334 | } | |
1335 | } | |
1336 | bh_lru_unlock(); | |
1337 | return ret; | |
1338 | } | |
1339 | ||
1340 | /* | |
1341 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1342 | * it in the LRU and mark it as accessed. If it is not present then return | |
1343 | * NULL | |
1344 | */ | |
1345 | struct buffer_head * | |
3991d3bd | 1346 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1347 | { |
1348 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1349 | ||
1350 | if (bh == NULL) { | |
385fd4c5 | 1351 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1352 | if (bh) |
1353 | bh_lru_install(bh); | |
1354 | } | |
1355 | if (bh) | |
1356 | touch_buffer(bh); | |
1357 | return bh; | |
1358 | } | |
1359 | EXPORT_SYMBOL(__find_get_block); | |
1360 | ||
1361 | /* | |
1362 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1363 | * which corresponds to the passed block_device, block and size. The | |
1364 | * returned buffer has its reference count incremented. | |
1365 | * | |
1366 | * __getblk() cannot fail - it just keeps trying. If you pass it an | |
1367 | * illegal block number, __getblk() will happily return a buffer_head | |
1368 | * which represents the non-existent block. Very weird. | |
1369 | * | |
1370 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() | |
1371 | * attempt is failing. FIXME, perhaps? | |
1372 | */ | |
1373 | struct buffer_head * | |
3991d3bd | 1374 | __getblk(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1375 | { |
1376 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1377 | ||
1378 | might_sleep(); | |
1379 | if (bh == NULL) | |
1380 | bh = __getblk_slow(bdev, block, size); | |
1381 | return bh; | |
1382 | } | |
1383 | EXPORT_SYMBOL(__getblk); | |
1384 | ||
1385 | /* | |
1386 | * Do async read-ahead on a buffer.. | |
1387 | */ | |
3991d3bd | 1388 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1389 | { |
1390 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1391 | if (likely(bh)) { |
1392 | ll_rw_block(READA, 1, &bh); | |
1393 | brelse(bh); | |
1394 | } | |
1da177e4 LT |
1395 | } |
1396 | EXPORT_SYMBOL(__breadahead); | |
1397 | ||
1398 | /** | |
1399 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1400 | * @bdev: the block_device to read from |
1da177e4 LT |
1401 | * @block: number of block |
1402 | * @size: size (in bytes) to read | |
1403 | * | |
1404 | * Reads a specified block, and returns buffer head that contains it. | |
1405 | * It returns NULL if the block was unreadable. | |
1406 | */ | |
1407 | struct buffer_head * | |
3991d3bd | 1408 | __bread(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1409 | { |
1410 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1411 | ||
a3e713b5 | 1412 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1413 | bh = __bread_slow(bh); |
1414 | return bh; | |
1415 | } | |
1416 | EXPORT_SYMBOL(__bread); | |
1417 | ||
1418 | /* | |
1419 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1420 | * This doesn't race because it runs in each cpu either in irq | |
1421 | * or with preempt disabled. | |
1422 | */ | |
1423 | static void invalidate_bh_lru(void *arg) | |
1424 | { | |
1425 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1426 | int i; | |
1427 | ||
1428 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1429 | brelse(b->bhs[i]); | |
1430 | b->bhs[i] = NULL; | |
1431 | } | |
1432 | put_cpu_var(bh_lrus); | |
1433 | } | |
1434 | ||
f9a14399 | 1435 | void invalidate_bh_lrus(void) |
1da177e4 LT |
1436 | { |
1437 | on_each_cpu(invalidate_bh_lru, NULL, 1, 1); | |
1438 | } | |
1439 | ||
1440 | void set_bh_page(struct buffer_head *bh, | |
1441 | struct page *page, unsigned long offset) | |
1442 | { | |
1443 | bh->b_page = page; | |
e827f923 | 1444 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1445 | if (PageHighMem(page)) |
1446 | /* | |
1447 | * This catches illegal uses and preserves the offset: | |
1448 | */ | |
1449 | bh->b_data = (char *)(0 + offset); | |
1450 | else | |
1451 | bh->b_data = page_address(page) + offset; | |
1452 | } | |
1453 | EXPORT_SYMBOL(set_bh_page); | |
1454 | ||
1455 | /* | |
1456 | * Called when truncating a buffer on a page completely. | |
1457 | */ | |
858119e1 | 1458 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1459 | { |
1460 | lock_buffer(bh); | |
1461 | clear_buffer_dirty(bh); | |
1462 | bh->b_bdev = NULL; | |
1463 | clear_buffer_mapped(bh); | |
1464 | clear_buffer_req(bh); | |
1465 | clear_buffer_new(bh); | |
1466 | clear_buffer_delay(bh); | |
33a266dd | 1467 | clear_buffer_unwritten(bh); |
1da177e4 LT |
1468 | unlock_buffer(bh); |
1469 | } | |
1470 | ||
1da177e4 LT |
1471 | /** |
1472 | * block_invalidatepage - invalidate part of all of a buffer-backed page | |
1473 | * | |
1474 | * @page: the page which is affected | |
1475 | * @offset: the index of the truncation point | |
1476 | * | |
1477 | * block_invalidatepage() is called when all or part of the page has become | |
1478 | * invalidatedby a truncate operation. | |
1479 | * | |
1480 | * block_invalidatepage() does not have to release all buffers, but it must | |
1481 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1482 | * is underway against any of the blocks which are outside the truncation | |
1483 | * point. Because the caller is about to free (and possibly reuse) those | |
1484 | * blocks on-disk. | |
1485 | */ | |
2ff28e22 | 1486 | void block_invalidatepage(struct page *page, unsigned long offset) |
1da177e4 LT |
1487 | { |
1488 | struct buffer_head *head, *bh, *next; | |
1489 | unsigned int curr_off = 0; | |
1da177e4 LT |
1490 | |
1491 | BUG_ON(!PageLocked(page)); | |
1492 | if (!page_has_buffers(page)) | |
1493 | goto out; | |
1494 | ||
1495 | head = page_buffers(page); | |
1496 | bh = head; | |
1497 | do { | |
1498 | unsigned int next_off = curr_off + bh->b_size; | |
1499 | next = bh->b_this_page; | |
1500 | ||
1501 | /* | |
1502 | * is this block fully invalidated? | |
1503 | */ | |
1504 | if (offset <= curr_off) | |
1505 | discard_buffer(bh); | |
1506 | curr_off = next_off; | |
1507 | bh = next; | |
1508 | } while (bh != head); | |
1509 | ||
1510 | /* | |
1511 | * We release buffers only if the entire page is being invalidated. | |
1512 | * The get_block cached value has been unconditionally invalidated, | |
1513 | * so real IO is not possible anymore. | |
1514 | */ | |
1515 | if (offset == 0) | |
2ff28e22 | 1516 | try_to_release_page(page, 0); |
1da177e4 | 1517 | out: |
2ff28e22 | 1518 | return; |
1da177e4 LT |
1519 | } |
1520 | EXPORT_SYMBOL(block_invalidatepage); | |
1521 | ||
1522 | /* | |
1523 | * We attach and possibly dirty the buffers atomically wrt | |
1524 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1525 | * is already excluded via the page lock. | |
1526 | */ | |
1527 | void create_empty_buffers(struct page *page, | |
1528 | unsigned long blocksize, unsigned long b_state) | |
1529 | { | |
1530 | struct buffer_head *bh, *head, *tail; | |
1531 | ||
1532 | head = alloc_page_buffers(page, blocksize, 1); | |
1533 | bh = head; | |
1534 | do { | |
1535 | bh->b_state |= b_state; | |
1536 | tail = bh; | |
1537 | bh = bh->b_this_page; | |
1538 | } while (bh); | |
1539 | tail->b_this_page = head; | |
1540 | ||
1541 | spin_lock(&page->mapping->private_lock); | |
1542 | if (PageUptodate(page) || PageDirty(page)) { | |
1543 | bh = head; | |
1544 | do { | |
1545 | if (PageDirty(page)) | |
1546 | set_buffer_dirty(bh); | |
1547 | if (PageUptodate(page)) | |
1548 | set_buffer_uptodate(bh); | |
1549 | bh = bh->b_this_page; | |
1550 | } while (bh != head); | |
1551 | } | |
1552 | attach_page_buffers(page, head); | |
1553 | spin_unlock(&page->mapping->private_lock); | |
1554 | } | |
1555 | EXPORT_SYMBOL(create_empty_buffers); | |
1556 | ||
1557 | /* | |
1558 | * We are taking a block for data and we don't want any output from any | |
1559 | * buffer-cache aliases starting from return from that function and | |
1560 | * until the moment when something will explicitly mark the buffer | |
1561 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1562 | * We don't even need to mark it not-uptodate - nobody can expect | |
1563 | * anything from a newly allocated buffer anyway. We used to used | |
1564 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1565 | * don't want to mark the alias unmapped, for example - it would confuse | |
1566 | * anyone who might pick it with bread() afterwards... | |
1567 | * | |
1568 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1569 | * be writeout I/O going on against recently-freed buffers. We don't | |
1570 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1571 | * only if we really need to. That happens here. | |
1572 | */ | |
1573 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1574 | { | |
1575 | struct buffer_head *old_bh; | |
1576 | ||
1577 | might_sleep(); | |
1578 | ||
385fd4c5 | 1579 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1580 | if (old_bh) { |
1581 | clear_buffer_dirty(old_bh); | |
1582 | wait_on_buffer(old_bh); | |
1583 | clear_buffer_req(old_bh); | |
1584 | __brelse(old_bh); | |
1585 | } | |
1586 | } | |
1587 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1588 | ||
1589 | /* | |
1590 | * NOTE! All mapped/uptodate combinations are valid: | |
1591 | * | |
1592 | * Mapped Uptodate Meaning | |
1593 | * | |
1594 | * No No "unknown" - must do get_block() | |
1595 | * No Yes "hole" - zero-filled | |
1596 | * Yes No "allocated" - allocated on disk, not read in | |
1597 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1598 | * | |
1599 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1600 | */ | |
1601 | ||
1602 | /* | |
1603 | * While block_write_full_page is writing back the dirty buffers under | |
1604 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1605 | * again at any time. We handle that by only looking at the buffer | |
1606 | * state inside lock_buffer(). | |
1607 | * | |
1608 | * If block_write_full_page() is called for regular writeback | |
1609 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1610 | * locked buffer. This only can happen if someone has written the buffer | |
1611 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1612 | * prevents this contention from occurring. | |
1613 | */ | |
1614 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
1615 | get_block_t *get_block, struct writeback_control *wbc) | |
1616 | { | |
1617 | int err; | |
1618 | sector_t block; | |
1619 | sector_t last_block; | |
f0fbd5fc | 1620 | struct buffer_head *bh, *head; |
b0cf2321 | 1621 | const unsigned blocksize = 1 << inode->i_blkbits; |
1da177e4 LT |
1622 | int nr_underway = 0; |
1623 | ||
1624 | BUG_ON(!PageLocked(page)); | |
1625 | ||
1626 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; | |
1627 | ||
1628 | if (!page_has_buffers(page)) { | |
b0cf2321 | 1629 | create_empty_buffers(page, blocksize, |
1da177e4 LT |
1630 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1631 | } | |
1632 | ||
1633 | /* | |
1634 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1635 | * here, and the (potentially unmapped) buffers may become dirty at | |
1636 | * any time. If a buffer becomes dirty here after we've inspected it | |
1637 | * then we just miss that fact, and the page stays dirty. | |
1638 | * | |
1639 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1640 | * handle that here by just cleaning them. | |
1641 | */ | |
1642 | ||
54b21a79 | 1643 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
1644 | head = page_buffers(page); |
1645 | bh = head; | |
1646 | ||
1647 | /* | |
1648 | * Get all the dirty buffers mapped to disk addresses and | |
1649 | * handle any aliases from the underlying blockdev's mapping. | |
1650 | */ | |
1651 | do { | |
1652 | if (block > last_block) { | |
1653 | /* | |
1654 | * mapped buffers outside i_size will occur, because | |
1655 | * this page can be outside i_size when there is a | |
1656 | * truncate in progress. | |
1657 | */ | |
1658 | /* | |
1659 | * The buffer was zeroed by block_write_full_page() | |
1660 | */ | |
1661 | clear_buffer_dirty(bh); | |
1662 | set_buffer_uptodate(bh); | |
1663 | } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { | |
b0cf2321 | 1664 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1665 | err = get_block(inode, block, bh, 1); |
1666 | if (err) | |
1667 | goto recover; | |
1668 | if (buffer_new(bh)) { | |
1669 | /* blockdev mappings never come here */ | |
1670 | clear_buffer_new(bh); | |
1671 | unmap_underlying_metadata(bh->b_bdev, | |
1672 | bh->b_blocknr); | |
1673 | } | |
1674 | } | |
1675 | bh = bh->b_this_page; | |
1676 | block++; | |
1677 | } while (bh != head); | |
1678 | ||
1679 | do { | |
1da177e4 LT |
1680 | if (!buffer_mapped(bh)) |
1681 | continue; | |
1682 | /* | |
1683 | * If it's a fully non-blocking write attempt and we cannot | |
1684 | * lock the buffer then redirty the page. Note that this can | |
1685 | * potentially cause a busy-wait loop from pdflush and kswapd | |
1686 | * activity, but those code paths have their own higher-level | |
1687 | * throttling. | |
1688 | */ | |
1689 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { | |
1690 | lock_buffer(bh); | |
1691 | } else if (test_set_buffer_locked(bh)) { | |
1692 | redirty_page_for_writepage(wbc, page); | |
1693 | continue; | |
1694 | } | |
1695 | if (test_clear_buffer_dirty(bh)) { | |
1696 | mark_buffer_async_write(bh); | |
1697 | } else { | |
1698 | unlock_buffer(bh); | |
1699 | } | |
1700 | } while ((bh = bh->b_this_page) != head); | |
1701 | ||
1702 | /* | |
1703 | * The page and its buffers are protected by PageWriteback(), so we can | |
1704 | * drop the bh refcounts early. | |
1705 | */ | |
1706 | BUG_ON(PageWriteback(page)); | |
1707 | set_page_writeback(page); | |
1da177e4 LT |
1708 | |
1709 | do { | |
1710 | struct buffer_head *next = bh->b_this_page; | |
1711 | if (buffer_async_write(bh)) { | |
1712 | submit_bh(WRITE, bh); | |
1713 | nr_underway++; | |
1714 | } | |
1da177e4 LT |
1715 | bh = next; |
1716 | } while (bh != head); | |
05937baa | 1717 | unlock_page(page); |
1da177e4 LT |
1718 | |
1719 | err = 0; | |
1720 | done: | |
1721 | if (nr_underway == 0) { | |
1722 | /* | |
1723 | * The page was marked dirty, but the buffers were | |
1724 | * clean. Someone wrote them back by hand with | |
1725 | * ll_rw_block/submit_bh. A rare case. | |
1726 | */ | |
1da177e4 | 1727 | end_page_writeback(page); |
3d67f2d7 | 1728 | |
1da177e4 LT |
1729 | /* |
1730 | * The page and buffer_heads can be released at any time from | |
1731 | * here on. | |
1732 | */ | |
1da177e4 LT |
1733 | } |
1734 | return err; | |
1735 | ||
1736 | recover: | |
1737 | /* | |
1738 | * ENOSPC, or some other error. We may already have added some | |
1739 | * blocks to the file, so we need to write these out to avoid | |
1740 | * exposing stale data. | |
1741 | * The page is currently locked and not marked for writeback | |
1742 | */ | |
1743 | bh = head; | |
1744 | /* Recovery: lock and submit the mapped buffers */ | |
1745 | do { | |
1da177e4 LT |
1746 | if (buffer_mapped(bh) && buffer_dirty(bh)) { |
1747 | lock_buffer(bh); | |
1748 | mark_buffer_async_write(bh); | |
1749 | } else { | |
1750 | /* | |
1751 | * The buffer may have been set dirty during | |
1752 | * attachment to a dirty page. | |
1753 | */ | |
1754 | clear_buffer_dirty(bh); | |
1755 | } | |
1756 | } while ((bh = bh->b_this_page) != head); | |
1757 | SetPageError(page); | |
1758 | BUG_ON(PageWriteback(page)); | |
7e4c3690 | 1759 | mapping_set_error(page->mapping, err); |
1da177e4 | 1760 | set_page_writeback(page); |
1da177e4 LT |
1761 | do { |
1762 | struct buffer_head *next = bh->b_this_page; | |
1763 | if (buffer_async_write(bh)) { | |
1764 | clear_buffer_dirty(bh); | |
1765 | submit_bh(WRITE, bh); | |
1766 | nr_underway++; | |
1767 | } | |
1da177e4 LT |
1768 | bh = next; |
1769 | } while (bh != head); | |
ffda9d30 | 1770 | unlock_page(page); |
1da177e4 LT |
1771 | goto done; |
1772 | } | |
1773 | ||
afddba49 NP |
1774 | /* |
1775 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1776 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1777 | * block data from leaking). And clear the new bit. | |
1778 | */ | |
1779 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1780 | { | |
1781 | unsigned int block_start, block_end; | |
1782 | struct buffer_head *head, *bh; | |
1783 | ||
1784 | BUG_ON(!PageLocked(page)); | |
1785 | if (!page_has_buffers(page)) | |
1786 | return; | |
1787 | ||
1788 | bh = head = page_buffers(page); | |
1789 | block_start = 0; | |
1790 | do { | |
1791 | block_end = block_start + bh->b_size; | |
1792 | ||
1793 | if (buffer_new(bh)) { | |
1794 | if (block_end > from && block_start < to) { | |
1795 | if (!PageUptodate(page)) { | |
1796 | unsigned start, size; | |
1797 | ||
1798 | start = max(from, block_start); | |
1799 | size = min(to, block_end) - start; | |
1800 | ||
1801 | zero_user_page(page, start, size, KM_USER0); | |
1802 | set_buffer_uptodate(bh); | |
1803 | } | |
1804 | ||
1805 | clear_buffer_new(bh); | |
1806 | mark_buffer_dirty(bh); | |
1807 | } | |
1808 | } | |
1809 | ||
1810 | block_start = block_end; | |
1811 | bh = bh->b_this_page; | |
1812 | } while (bh != head); | |
1813 | } | |
1814 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1815 | ||
1da177e4 LT |
1816 | static int __block_prepare_write(struct inode *inode, struct page *page, |
1817 | unsigned from, unsigned to, get_block_t *get_block) | |
1818 | { | |
1819 | unsigned block_start, block_end; | |
1820 | sector_t block; | |
1821 | int err = 0; | |
1822 | unsigned blocksize, bbits; | |
1823 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1824 | ||
1825 | BUG_ON(!PageLocked(page)); | |
1826 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1827 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1828 | BUG_ON(from > to); | |
1829 | ||
1830 | blocksize = 1 << inode->i_blkbits; | |
1831 | if (!page_has_buffers(page)) | |
1832 | create_empty_buffers(page, blocksize, 0); | |
1833 | head = page_buffers(page); | |
1834 | ||
1835 | bbits = inode->i_blkbits; | |
1836 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1837 | ||
1838 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1839 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1840 | block_end = block_start + blocksize; | |
1841 | if (block_end <= from || block_start >= to) { | |
1842 | if (PageUptodate(page)) { | |
1843 | if (!buffer_uptodate(bh)) | |
1844 | set_buffer_uptodate(bh); | |
1845 | } | |
1846 | continue; | |
1847 | } | |
1848 | if (buffer_new(bh)) | |
1849 | clear_buffer_new(bh); | |
1850 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1851 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1852 | err = get_block(inode, block, bh, 1); |
1853 | if (err) | |
f3ddbdc6 | 1854 | break; |
1da177e4 | 1855 | if (buffer_new(bh)) { |
1da177e4 LT |
1856 | unmap_underlying_metadata(bh->b_bdev, |
1857 | bh->b_blocknr); | |
1858 | if (PageUptodate(page)) { | |
637aff46 | 1859 | clear_buffer_new(bh); |
1da177e4 | 1860 | set_buffer_uptodate(bh); |
637aff46 | 1861 | mark_buffer_dirty(bh); |
1da177e4 LT |
1862 | continue; |
1863 | } | |
1864 | if (block_end > to || block_start < from) { | |
1865 | void *kaddr; | |
1866 | ||
1867 | kaddr = kmap_atomic(page, KM_USER0); | |
1868 | if (block_end > to) | |
1869 | memset(kaddr+to, 0, | |
1870 | block_end-to); | |
1871 | if (block_start < from) | |
1872 | memset(kaddr+block_start, | |
1873 | 0, from-block_start); | |
1874 | flush_dcache_page(page); | |
1875 | kunmap_atomic(kaddr, KM_USER0); | |
1876 | } | |
1877 | continue; | |
1878 | } | |
1879 | } | |
1880 | if (PageUptodate(page)) { | |
1881 | if (!buffer_uptodate(bh)) | |
1882 | set_buffer_uptodate(bh); | |
1883 | continue; | |
1884 | } | |
1885 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
33a266dd | 1886 | !buffer_unwritten(bh) && |
1da177e4 LT |
1887 | (block_start < from || block_end > to)) { |
1888 | ll_rw_block(READ, 1, &bh); | |
1889 | *wait_bh++=bh; | |
1890 | } | |
1891 | } | |
1892 | /* | |
1893 | * If we issued read requests - let them complete. | |
1894 | */ | |
1895 | while(wait_bh > wait) { | |
1896 | wait_on_buffer(*--wait_bh); | |
1897 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1898 | err = -EIO; |
1da177e4 | 1899 | } |
afddba49 NP |
1900 | if (unlikely(err)) |
1901 | page_zero_new_buffers(page, from, to); | |
1da177e4 LT |
1902 | return err; |
1903 | } | |
1904 | ||
1905 | static int __block_commit_write(struct inode *inode, struct page *page, | |
1906 | unsigned from, unsigned to) | |
1907 | { | |
1908 | unsigned block_start, block_end; | |
1909 | int partial = 0; | |
1910 | unsigned blocksize; | |
1911 | struct buffer_head *bh, *head; | |
1912 | ||
1913 | blocksize = 1 << inode->i_blkbits; | |
1914 | ||
1915 | for(bh = head = page_buffers(page), block_start = 0; | |
1916 | bh != head || !block_start; | |
1917 | block_start=block_end, bh = bh->b_this_page) { | |
1918 | block_end = block_start + blocksize; | |
1919 | if (block_end <= from || block_start >= to) { | |
1920 | if (!buffer_uptodate(bh)) | |
1921 | partial = 1; | |
1922 | } else { | |
1923 | set_buffer_uptodate(bh); | |
1924 | mark_buffer_dirty(bh); | |
1925 | } | |
afddba49 | 1926 | clear_buffer_new(bh); |
1da177e4 LT |
1927 | } |
1928 | ||
1929 | /* | |
1930 | * If this is a partial write which happened to make all buffers | |
1931 | * uptodate then we can optimize away a bogus readpage() for | |
1932 | * the next read(). Here we 'discover' whether the page went | |
1933 | * uptodate as a result of this (potentially partial) write. | |
1934 | */ | |
1935 | if (!partial) | |
1936 | SetPageUptodate(page); | |
1937 | return 0; | |
1938 | } | |
1939 | ||
afddba49 NP |
1940 | /* |
1941 | * block_write_begin takes care of the basic task of block allocation and | |
1942 | * bringing partial write blocks uptodate first. | |
1943 | * | |
1944 | * If *pagep is not NULL, then block_write_begin uses the locked page | |
1945 | * at *pagep rather than allocating its own. In this case, the page will | |
1946 | * not be unlocked or deallocated on failure. | |
1947 | */ | |
1948 | int block_write_begin(struct file *file, struct address_space *mapping, | |
1949 | loff_t pos, unsigned len, unsigned flags, | |
1950 | struct page **pagep, void **fsdata, | |
1951 | get_block_t *get_block) | |
1952 | { | |
1953 | struct inode *inode = mapping->host; | |
1954 | int status = 0; | |
1955 | struct page *page; | |
1956 | pgoff_t index; | |
1957 | unsigned start, end; | |
1958 | int ownpage = 0; | |
1959 | ||
1960 | index = pos >> PAGE_CACHE_SHIFT; | |
1961 | start = pos & (PAGE_CACHE_SIZE - 1); | |
1962 | end = start + len; | |
1963 | ||
1964 | page = *pagep; | |
1965 | if (page == NULL) { | |
1966 | ownpage = 1; | |
1967 | page = __grab_cache_page(mapping, index); | |
1968 | if (!page) { | |
1969 | status = -ENOMEM; | |
1970 | goto out; | |
1971 | } | |
1972 | *pagep = page; | |
1973 | } else | |
1974 | BUG_ON(!PageLocked(page)); | |
1975 | ||
1976 | status = __block_prepare_write(inode, page, start, end, get_block); | |
1977 | if (unlikely(status)) { | |
1978 | ClearPageUptodate(page); | |
1979 | ||
1980 | if (ownpage) { | |
1981 | unlock_page(page); | |
1982 | page_cache_release(page); | |
1983 | *pagep = NULL; | |
1984 | ||
1985 | /* | |
1986 | * prepare_write() may have instantiated a few blocks | |
1987 | * outside i_size. Trim these off again. Don't need | |
1988 | * i_size_read because we hold i_mutex. | |
1989 | */ | |
1990 | if (pos + len > inode->i_size) | |
1991 | vmtruncate(inode, inode->i_size); | |
1992 | } | |
1993 | goto out; | |
1994 | } | |
1995 | ||
1996 | out: | |
1997 | return status; | |
1998 | } | |
1999 | EXPORT_SYMBOL(block_write_begin); | |
2000 | ||
2001 | int block_write_end(struct file *file, struct address_space *mapping, | |
2002 | loff_t pos, unsigned len, unsigned copied, | |
2003 | struct page *page, void *fsdata) | |
2004 | { | |
2005 | struct inode *inode = mapping->host; | |
2006 | unsigned start; | |
2007 | ||
2008 | start = pos & (PAGE_CACHE_SIZE - 1); | |
2009 | ||
2010 | if (unlikely(copied < len)) { | |
2011 | /* | |
2012 | * The buffers that were written will now be uptodate, so we | |
2013 | * don't have to worry about a readpage reading them and | |
2014 | * overwriting a partial write. However if we have encountered | |
2015 | * a short write and only partially written into a buffer, it | |
2016 | * will not be marked uptodate, so a readpage might come in and | |
2017 | * destroy our partial write. | |
2018 | * | |
2019 | * Do the simplest thing, and just treat any short write to a | |
2020 | * non uptodate page as a zero-length write, and force the | |
2021 | * caller to redo the whole thing. | |
2022 | */ | |
2023 | if (!PageUptodate(page)) | |
2024 | copied = 0; | |
2025 | ||
2026 | page_zero_new_buffers(page, start+copied, start+len); | |
2027 | } | |
2028 | flush_dcache_page(page); | |
2029 | ||
2030 | /* This could be a short (even 0-length) commit */ | |
2031 | __block_commit_write(inode, page, start, start+copied); | |
2032 | ||
2033 | return copied; | |
2034 | } | |
2035 | EXPORT_SYMBOL(block_write_end); | |
2036 | ||
2037 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2038 | loff_t pos, unsigned len, unsigned copied, | |
2039 | struct page *page, void *fsdata) | |
2040 | { | |
2041 | struct inode *inode = mapping->host; | |
2042 | ||
2043 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
2044 | ||
2045 | /* | |
2046 | * No need to use i_size_read() here, the i_size | |
2047 | * cannot change under us because we hold i_mutex. | |
2048 | * | |
2049 | * But it's important to update i_size while still holding page lock: | |
2050 | * page writeout could otherwise come in and zero beyond i_size. | |
2051 | */ | |
2052 | if (pos+copied > inode->i_size) { | |
2053 | i_size_write(inode, pos+copied); | |
2054 | mark_inode_dirty(inode); | |
2055 | } | |
2056 | ||
2057 | unlock_page(page); | |
2058 | page_cache_release(page); | |
2059 | ||
2060 | return copied; | |
2061 | } | |
2062 | EXPORT_SYMBOL(generic_write_end); | |
2063 | ||
1da177e4 LT |
2064 | /* |
2065 | * Generic "read page" function for block devices that have the normal | |
2066 | * get_block functionality. This is most of the block device filesystems. | |
2067 | * Reads the page asynchronously --- the unlock_buffer() and | |
2068 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2069 | * page struct once IO has completed. | |
2070 | */ | |
2071 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2072 | { | |
2073 | struct inode *inode = page->mapping->host; | |
2074 | sector_t iblock, lblock; | |
2075 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
2076 | unsigned int blocksize; | |
2077 | int nr, i; | |
2078 | int fully_mapped = 1; | |
2079 | ||
cd7619d6 | 2080 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
2081 | blocksize = 1 << inode->i_blkbits; |
2082 | if (!page_has_buffers(page)) | |
2083 | create_empty_buffers(page, blocksize, 0); | |
2084 | head = page_buffers(page); | |
2085 | ||
2086 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
2087 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; | |
2088 | bh = head; | |
2089 | nr = 0; | |
2090 | i = 0; | |
2091 | ||
2092 | do { | |
2093 | if (buffer_uptodate(bh)) | |
2094 | continue; | |
2095 | ||
2096 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2097 | int err = 0; |
2098 | ||
1da177e4 LT |
2099 | fully_mapped = 0; |
2100 | if (iblock < lblock) { | |
b0cf2321 | 2101 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2102 | err = get_block(inode, iblock, bh, 0); |
2103 | if (err) | |
1da177e4 LT |
2104 | SetPageError(page); |
2105 | } | |
2106 | if (!buffer_mapped(bh)) { | |
01f2705d ND |
2107 | zero_user_page(page, i * blocksize, blocksize, |
2108 | KM_USER0); | |
c64610ba AM |
2109 | if (!err) |
2110 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2111 | continue; |
2112 | } | |
2113 | /* | |
2114 | * get_block() might have updated the buffer | |
2115 | * synchronously | |
2116 | */ | |
2117 | if (buffer_uptodate(bh)) | |
2118 | continue; | |
2119 | } | |
2120 | arr[nr++] = bh; | |
2121 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2122 | ||
2123 | if (fully_mapped) | |
2124 | SetPageMappedToDisk(page); | |
2125 | ||
2126 | if (!nr) { | |
2127 | /* | |
2128 | * All buffers are uptodate - we can set the page uptodate | |
2129 | * as well. But not if get_block() returned an error. | |
2130 | */ | |
2131 | if (!PageError(page)) | |
2132 | SetPageUptodate(page); | |
2133 | unlock_page(page); | |
2134 | return 0; | |
2135 | } | |
2136 | ||
2137 | /* Stage two: lock the buffers */ | |
2138 | for (i = 0; i < nr; i++) { | |
2139 | bh = arr[i]; | |
2140 | lock_buffer(bh); | |
2141 | mark_buffer_async_read(bh); | |
2142 | } | |
2143 | ||
2144 | /* | |
2145 | * Stage 3: start the IO. Check for uptodateness | |
2146 | * inside the buffer lock in case another process reading | |
2147 | * the underlying blockdev brought it uptodate (the sct fix). | |
2148 | */ | |
2149 | for (i = 0; i < nr; i++) { | |
2150 | bh = arr[i]; | |
2151 | if (buffer_uptodate(bh)) | |
2152 | end_buffer_async_read(bh, 1); | |
2153 | else | |
2154 | submit_bh(READ, bh); | |
2155 | } | |
2156 | return 0; | |
2157 | } | |
2158 | ||
2159 | /* utility function for filesystems that need to do work on expanding | |
89e10787 | 2160 | * truncates. Uses filesystem pagecache writes to allow the filesystem to |
1da177e4 LT |
2161 | * deal with the hole. |
2162 | */ | |
89e10787 | 2163 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
1da177e4 LT |
2164 | { |
2165 | struct address_space *mapping = inode->i_mapping; | |
2166 | struct page *page; | |
89e10787 | 2167 | void *fsdata; |
05eb0b51 | 2168 | unsigned long limit; |
1da177e4 LT |
2169 | int err; |
2170 | ||
2171 | err = -EFBIG; | |
2172 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
2173 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { | |
2174 | send_sig(SIGXFSZ, current, 0); | |
2175 | goto out; | |
2176 | } | |
2177 | if (size > inode->i_sb->s_maxbytes) | |
2178 | goto out; | |
2179 | ||
89e10787 NP |
2180 | err = pagecache_write_begin(NULL, mapping, size, 0, |
2181 | AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, | |
2182 | &page, &fsdata); | |
2183 | if (err) | |
05eb0b51 | 2184 | goto out; |
05eb0b51 | 2185 | |
89e10787 NP |
2186 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
2187 | BUG_ON(err > 0); | |
05eb0b51 | 2188 | |
1da177e4 LT |
2189 | out: |
2190 | return err; | |
2191 | } | |
2192 | ||
89e10787 NP |
2193 | int cont_expand_zero(struct file *file, struct address_space *mapping, |
2194 | loff_t pos, loff_t *bytes) | |
1da177e4 | 2195 | { |
1da177e4 | 2196 | struct inode *inode = mapping->host; |
1da177e4 | 2197 | unsigned blocksize = 1 << inode->i_blkbits; |
89e10787 NP |
2198 | struct page *page; |
2199 | void *fsdata; | |
2200 | pgoff_t index, curidx; | |
2201 | loff_t curpos; | |
2202 | unsigned zerofrom, offset, len; | |
2203 | int err = 0; | |
1da177e4 | 2204 | |
89e10787 NP |
2205 | index = pos >> PAGE_CACHE_SHIFT; |
2206 | offset = pos & ~PAGE_CACHE_MASK; | |
2207 | ||
2208 | while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { | |
2209 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 LT |
2210 | if (zerofrom & (blocksize-1)) { |
2211 | *bytes |= (blocksize-1); | |
2212 | (*bytes)++; | |
2213 | } | |
89e10787 | 2214 | len = PAGE_CACHE_SIZE - zerofrom; |
1da177e4 | 2215 | |
89e10787 NP |
2216 | err = pagecache_write_begin(file, mapping, curpos, len, |
2217 | AOP_FLAG_UNINTERRUPTIBLE, | |
2218 | &page, &fsdata); | |
2219 | if (err) | |
2220 | goto out; | |
2221 | zero_user_page(page, zerofrom, len, KM_USER0); | |
2222 | err = pagecache_write_end(file, mapping, curpos, len, len, | |
2223 | page, fsdata); | |
2224 | if (err < 0) | |
2225 | goto out; | |
2226 | BUG_ON(err != len); | |
2227 | err = 0; | |
2228 | } | |
1da177e4 | 2229 | |
89e10787 NP |
2230 | /* page covers the boundary, find the boundary offset */ |
2231 | if (index == curidx) { | |
2232 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 | 2233 | /* if we will expand the thing last block will be filled */ |
89e10787 NP |
2234 | if (offset <= zerofrom) { |
2235 | goto out; | |
2236 | } | |
2237 | if (zerofrom & (blocksize-1)) { | |
1da177e4 LT |
2238 | *bytes |= (blocksize-1); |
2239 | (*bytes)++; | |
2240 | } | |
89e10787 | 2241 | len = offset - zerofrom; |
1da177e4 | 2242 | |
89e10787 NP |
2243 | err = pagecache_write_begin(file, mapping, curpos, len, |
2244 | AOP_FLAG_UNINTERRUPTIBLE, | |
2245 | &page, &fsdata); | |
2246 | if (err) | |
2247 | goto out; | |
2248 | zero_user_page(page, zerofrom, len, KM_USER0); | |
2249 | err = pagecache_write_end(file, mapping, curpos, len, len, | |
2250 | page, fsdata); | |
2251 | if (err < 0) | |
2252 | goto out; | |
2253 | BUG_ON(err != len); | |
2254 | err = 0; | |
1da177e4 | 2255 | } |
89e10787 NP |
2256 | out: |
2257 | return err; | |
2258 | } | |
2259 | ||
2260 | /* | |
2261 | * For moronic filesystems that do not allow holes in file. | |
2262 | * We may have to extend the file. | |
2263 | */ | |
2264 | int cont_write_begin(struct file *file, struct address_space *mapping, | |
2265 | loff_t pos, unsigned len, unsigned flags, | |
2266 | struct page **pagep, void **fsdata, | |
2267 | get_block_t *get_block, loff_t *bytes) | |
2268 | { | |
2269 | struct inode *inode = mapping->host; | |
2270 | unsigned blocksize = 1 << inode->i_blkbits; | |
2271 | unsigned zerofrom; | |
2272 | int err; | |
2273 | ||
2274 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2275 | if (err) | |
2276 | goto out; | |
2277 | ||
2278 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2279 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { | |
2280 | *bytes |= (blocksize-1); | |
2281 | (*bytes)++; | |
1da177e4 | 2282 | } |
1da177e4 | 2283 | |
89e10787 NP |
2284 | *pagep = NULL; |
2285 | err = block_write_begin(file, mapping, pos, len, | |
2286 | flags, pagep, fsdata, get_block); | |
1da177e4 | 2287 | out: |
89e10787 | 2288 | return err; |
1da177e4 LT |
2289 | } |
2290 | ||
2291 | int block_prepare_write(struct page *page, unsigned from, unsigned to, | |
2292 | get_block_t *get_block) | |
2293 | { | |
2294 | struct inode *inode = page->mapping->host; | |
2295 | int err = __block_prepare_write(inode, page, from, to, get_block); | |
2296 | if (err) | |
2297 | ClearPageUptodate(page); | |
2298 | return err; | |
2299 | } | |
2300 | ||
2301 | int block_commit_write(struct page *page, unsigned from, unsigned to) | |
2302 | { | |
2303 | struct inode *inode = page->mapping->host; | |
2304 | __block_commit_write(inode,page,from,to); | |
2305 | return 0; | |
2306 | } | |
2307 | ||
2308 | int generic_commit_write(struct file *file, struct page *page, | |
2309 | unsigned from, unsigned to) | |
2310 | { | |
2311 | struct inode *inode = page->mapping->host; | |
2312 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2313 | __block_commit_write(inode,page,from,to); | |
2314 | /* | |
2315 | * No need to use i_size_read() here, the i_size | |
1b1dcc1b | 2316 | * cannot change under us because we hold i_mutex. |
1da177e4 LT |
2317 | */ |
2318 | if (pos > inode->i_size) { | |
2319 | i_size_write(inode, pos); | |
2320 | mark_inode_dirty(inode); | |
2321 | } | |
2322 | return 0; | |
2323 | } | |
2324 | ||
54171690 DC |
2325 | /* |
2326 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2327 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2328 | * be careful to check for EOF conditions here. We set the page up correctly | |
2329 | * for a written page which means we get ENOSPC checking when writing into | |
2330 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2331 | * support these features. | |
2332 | * | |
2333 | * We are not allowed to take the i_mutex here so we have to play games to | |
2334 | * protect against truncate races as the page could now be beyond EOF. Because | |
2335 | * vmtruncate() writes the inode size before removing pages, once we have the | |
2336 | * page lock we can determine safely if the page is beyond EOF. If it is not | |
2337 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2338 | * unlock the page. | |
2339 | */ | |
2340 | int | |
2341 | block_page_mkwrite(struct vm_area_struct *vma, struct page *page, | |
2342 | get_block_t get_block) | |
2343 | { | |
2344 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; | |
2345 | unsigned long end; | |
2346 | loff_t size; | |
2347 | int ret = -EINVAL; | |
2348 | ||
2349 | lock_page(page); | |
2350 | size = i_size_read(inode); | |
2351 | if ((page->mapping != inode->i_mapping) || | |
18336338 | 2352 | (page_offset(page) > size)) { |
54171690 DC |
2353 | /* page got truncated out from underneath us */ |
2354 | goto out_unlock; | |
2355 | } | |
2356 | ||
2357 | /* page is wholly or partially inside EOF */ | |
2358 | if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) | |
2359 | end = size & ~PAGE_CACHE_MASK; | |
2360 | else | |
2361 | end = PAGE_CACHE_SIZE; | |
2362 | ||
2363 | ret = block_prepare_write(page, 0, end, get_block); | |
2364 | if (!ret) | |
2365 | ret = block_commit_write(page, 0, end); | |
2366 | ||
2367 | out_unlock: | |
2368 | unlock_page(page); | |
2369 | return ret; | |
2370 | } | |
1da177e4 LT |
2371 | |
2372 | /* | |
03158cd7 | 2373 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed |
1da177e4 LT |
2374 | * immediately, while under the page lock. So it needs a special end_io |
2375 | * handler which does not touch the bh after unlocking it. | |
1da177e4 LT |
2376 | */ |
2377 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2378 | { | |
68671f35 | 2379 | __end_buffer_read_notouch(bh, uptodate); |
1da177e4 LT |
2380 | } |
2381 | ||
03158cd7 NP |
2382 | /* |
2383 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2384 | * the page (converting it to circular linked list and taking care of page | |
2385 | * dirty races). | |
2386 | */ | |
2387 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2388 | { | |
2389 | struct buffer_head *bh; | |
2390 | ||
2391 | BUG_ON(!PageLocked(page)); | |
2392 | ||
2393 | spin_lock(&page->mapping->private_lock); | |
2394 | bh = head; | |
2395 | do { | |
2396 | if (PageDirty(page)) | |
2397 | set_buffer_dirty(bh); | |
2398 | if (!bh->b_this_page) | |
2399 | bh->b_this_page = head; | |
2400 | bh = bh->b_this_page; | |
2401 | } while (bh != head); | |
2402 | attach_page_buffers(page, head); | |
2403 | spin_unlock(&page->mapping->private_lock); | |
2404 | } | |
2405 | ||
1da177e4 LT |
2406 | /* |
2407 | * On entry, the page is fully not uptodate. | |
2408 | * On exit the page is fully uptodate in the areas outside (from,to) | |
2409 | */ | |
03158cd7 NP |
2410 | int nobh_write_begin(struct file *file, struct address_space *mapping, |
2411 | loff_t pos, unsigned len, unsigned flags, | |
2412 | struct page **pagep, void **fsdata, | |
1da177e4 LT |
2413 | get_block_t *get_block) |
2414 | { | |
03158cd7 | 2415 | struct inode *inode = mapping->host; |
1da177e4 LT |
2416 | const unsigned blkbits = inode->i_blkbits; |
2417 | const unsigned blocksize = 1 << blkbits; | |
a4b0672d | 2418 | struct buffer_head *head, *bh; |
03158cd7 NP |
2419 | struct page *page; |
2420 | pgoff_t index; | |
2421 | unsigned from, to; | |
1da177e4 | 2422 | unsigned block_in_page; |
a4b0672d | 2423 | unsigned block_start, block_end; |
1da177e4 LT |
2424 | sector_t block_in_file; |
2425 | char *kaddr; | |
2426 | int nr_reads = 0; | |
1da177e4 LT |
2427 | int ret = 0; |
2428 | int is_mapped_to_disk = 1; | |
1da177e4 | 2429 | |
03158cd7 NP |
2430 | index = pos >> PAGE_CACHE_SHIFT; |
2431 | from = pos & (PAGE_CACHE_SIZE - 1); | |
2432 | to = from + len; | |
2433 | ||
2434 | page = __grab_cache_page(mapping, index); | |
2435 | if (!page) | |
2436 | return -ENOMEM; | |
2437 | *pagep = page; | |
2438 | *fsdata = NULL; | |
2439 | ||
2440 | if (page_has_buffers(page)) { | |
2441 | unlock_page(page); | |
2442 | page_cache_release(page); | |
2443 | *pagep = NULL; | |
2444 | return block_write_begin(file, mapping, pos, len, flags, pagep, | |
2445 | fsdata, get_block); | |
2446 | } | |
a4b0672d | 2447 | |
1da177e4 LT |
2448 | if (PageMappedToDisk(page)) |
2449 | return 0; | |
2450 | ||
a4b0672d NP |
2451 | /* |
2452 | * Allocate buffers so that we can keep track of state, and potentially | |
2453 | * attach them to the page if an error occurs. In the common case of | |
2454 | * no error, they will just be freed again without ever being attached | |
2455 | * to the page (which is all OK, because we're under the page lock). | |
2456 | * | |
2457 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2458 | * than the circular one we're used to. | |
2459 | */ | |
2460 | head = alloc_page_buffers(page, blocksize, 0); | |
03158cd7 NP |
2461 | if (!head) { |
2462 | ret = -ENOMEM; | |
2463 | goto out_release; | |
2464 | } | |
a4b0672d | 2465 | |
1da177e4 | 2466 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
1da177e4 LT |
2467 | |
2468 | /* | |
2469 | * We loop across all blocks in the page, whether or not they are | |
2470 | * part of the affected region. This is so we can discover if the | |
2471 | * page is fully mapped-to-disk. | |
2472 | */ | |
a4b0672d | 2473 | for (block_start = 0, block_in_page = 0, bh = head; |
1da177e4 | 2474 | block_start < PAGE_CACHE_SIZE; |
a4b0672d | 2475 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
1da177e4 LT |
2476 | int create; |
2477 | ||
a4b0672d NP |
2478 | block_end = block_start + blocksize; |
2479 | bh->b_state = 0; | |
1da177e4 LT |
2480 | create = 1; |
2481 | if (block_start >= to) | |
2482 | create = 0; | |
2483 | ret = get_block(inode, block_in_file + block_in_page, | |
a4b0672d | 2484 | bh, create); |
1da177e4 LT |
2485 | if (ret) |
2486 | goto failed; | |
a4b0672d | 2487 | if (!buffer_mapped(bh)) |
1da177e4 | 2488 | is_mapped_to_disk = 0; |
a4b0672d NP |
2489 | if (buffer_new(bh)) |
2490 | unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); | |
2491 | if (PageUptodate(page)) { | |
2492 | set_buffer_uptodate(bh); | |
1da177e4 | 2493 | continue; |
a4b0672d NP |
2494 | } |
2495 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
1da177e4 | 2496 | kaddr = kmap_atomic(page, KM_USER0); |
22c8ca78 | 2497 | if (block_start < from) |
1da177e4 | 2498 | memset(kaddr+block_start, 0, from-block_start); |
22c8ca78 | 2499 | if (block_end > to) |
1da177e4 | 2500 | memset(kaddr + to, 0, block_end - to); |
1da177e4 LT |
2501 | flush_dcache_page(page); |
2502 | kunmap_atomic(kaddr, KM_USER0); | |
2503 | continue; | |
2504 | } | |
a4b0672d | 2505 | if (buffer_uptodate(bh)) |
1da177e4 LT |
2506 | continue; /* reiserfs does this */ |
2507 | if (block_start < from || block_end > to) { | |
a4b0672d NP |
2508 | lock_buffer(bh); |
2509 | bh->b_end_io = end_buffer_read_nobh; | |
2510 | submit_bh(READ, bh); | |
2511 | nr_reads++; | |
1da177e4 LT |
2512 | } |
2513 | } | |
2514 | ||
2515 | if (nr_reads) { | |
1da177e4 LT |
2516 | /* |
2517 | * The page is locked, so these buffers are protected from | |
2518 | * any VM or truncate activity. Hence we don't need to care | |
2519 | * for the buffer_head refcounts. | |
2520 | */ | |
a4b0672d | 2521 | for (bh = head; bh; bh = bh->b_this_page) { |
1da177e4 LT |
2522 | wait_on_buffer(bh); |
2523 | if (!buffer_uptodate(bh)) | |
2524 | ret = -EIO; | |
1da177e4 LT |
2525 | } |
2526 | if (ret) | |
2527 | goto failed; | |
2528 | } | |
2529 | ||
2530 | if (is_mapped_to_disk) | |
2531 | SetPageMappedToDisk(page); | |
1da177e4 | 2532 | |
03158cd7 | 2533 | *fsdata = head; /* to be released by nobh_write_end */ |
a4b0672d | 2534 | |
1da177e4 LT |
2535 | return 0; |
2536 | ||
2537 | failed: | |
03158cd7 | 2538 | BUG_ON(!ret); |
1da177e4 | 2539 | /* |
a4b0672d NP |
2540 | * Error recovery is a bit difficult. We need to zero out blocks that |
2541 | * were newly allocated, and dirty them to ensure they get written out. | |
2542 | * Buffers need to be attached to the page at this point, otherwise | |
2543 | * the handling of potential IO errors during writeout would be hard | |
2544 | * (could try doing synchronous writeout, but what if that fails too?) | |
1da177e4 | 2545 | */ |
03158cd7 NP |
2546 | attach_nobh_buffers(page, head); |
2547 | page_zero_new_buffers(page, from, to); | |
a4b0672d | 2548 | |
03158cd7 NP |
2549 | out_release: |
2550 | unlock_page(page); | |
2551 | page_cache_release(page); | |
2552 | *pagep = NULL; | |
a4b0672d | 2553 | |
03158cd7 NP |
2554 | if (pos + len > inode->i_size) |
2555 | vmtruncate(inode, inode->i_size); | |
a4b0672d | 2556 | |
1da177e4 LT |
2557 | return ret; |
2558 | } | |
03158cd7 | 2559 | EXPORT_SYMBOL(nobh_write_begin); |
1da177e4 | 2560 | |
03158cd7 NP |
2561 | int nobh_write_end(struct file *file, struct address_space *mapping, |
2562 | loff_t pos, unsigned len, unsigned copied, | |
2563 | struct page *page, void *fsdata) | |
1da177e4 LT |
2564 | { |
2565 | struct inode *inode = page->mapping->host; | |
03158cd7 NP |
2566 | struct buffer_head *head = NULL; |
2567 | struct buffer_head *bh; | |
1da177e4 | 2568 | |
03158cd7 NP |
2569 | if (!PageMappedToDisk(page)) { |
2570 | if (unlikely(copied < len) && !page_has_buffers(page)) | |
2571 | attach_nobh_buffers(page, head); | |
2572 | if (page_has_buffers(page)) | |
2573 | return generic_write_end(file, mapping, pos, len, | |
2574 | copied, page, fsdata); | |
2575 | } | |
a4b0672d | 2576 | |
22c8ca78 | 2577 | SetPageUptodate(page); |
1da177e4 | 2578 | set_page_dirty(page); |
03158cd7 NP |
2579 | if (pos+copied > inode->i_size) { |
2580 | i_size_write(inode, pos+copied); | |
1da177e4 LT |
2581 | mark_inode_dirty(inode); |
2582 | } | |
03158cd7 NP |
2583 | |
2584 | unlock_page(page); | |
2585 | page_cache_release(page); | |
2586 | ||
2587 | head = fsdata; | |
2588 | while (head) { | |
2589 | bh = head; | |
2590 | head = head->b_this_page; | |
2591 | free_buffer_head(bh); | |
2592 | } | |
2593 | ||
2594 | return copied; | |
1da177e4 | 2595 | } |
03158cd7 | 2596 | EXPORT_SYMBOL(nobh_write_end); |
1da177e4 LT |
2597 | |
2598 | /* | |
2599 | * nobh_writepage() - based on block_full_write_page() except | |
2600 | * that it tries to operate without attaching bufferheads to | |
2601 | * the page. | |
2602 | */ | |
2603 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2604 | struct writeback_control *wbc) | |
2605 | { | |
2606 | struct inode * const inode = page->mapping->host; | |
2607 | loff_t i_size = i_size_read(inode); | |
2608 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2609 | unsigned offset; | |
1da177e4 LT |
2610 | int ret; |
2611 | ||
2612 | /* Is the page fully inside i_size? */ | |
2613 | if (page->index < end_index) | |
2614 | goto out; | |
2615 | ||
2616 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2617 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2618 | if (page->index >= end_index+1 || !offset) { | |
2619 | /* | |
2620 | * The page may have dirty, unmapped buffers. For example, | |
2621 | * they may have been added in ext3_writepage(). Make them | |
2622 | * freeable here, so the page does not leak. | |
2623 | */ | |
2624 | #if 0 | |
2625 | /* Not really sure about this - do we need this ? */ | |
2626 | if (page->mapping->a_ops->invalidatepage) | |
2627 | page->mapping->a_ops->invalidatepage(page, offset); | |
2628 | #endif | |
2629 | unlock_page(page); | |
2630 | return 0; /* don't care */ | |
2631 | } | |
2632 | ||
2633 | /* | |
2634 | * The page straddles i_size. It must be zeroed out on each and every | |
2635 | * writepage invocation because it may be mmapped. "A file is mapped | |
2636 | * in multiples of the page size. For a file that is not a multiple of | |
2637 | * the page size, the remaining memory is zeroed when mapped, and | |
2638 | * writes to that region are not written out to the file." | |
2639 | */ | |
01f2705d | 2640 | zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0); |
1da177e4 LT |
2641 | out: |
2642 | ret = mpage_writepage(page, get_block, wbc); | |
2643 | if (ret == -EAGAIN) | |
2644 | ret = __block_write_full_page(inode, page, get_block, wbc); | |
2645 | return ret; | |
2646 | } | |
2647 | EXPORT_SYMBOL(nobh_writepage); | |
2648 | ||
03158cd7 NP |
2649 | int nobh_truncate_page(struct address_space *mapping, |
2650 | loff_t from, get_block_t *get_block) | |
1da177e4 | 2651 | { |
1da177e4 LT |
2652 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2653 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
03158cd7 NP |
2654 | unsigned blocksize; |
2655 | sector_t iblock; | |
2656 | unsigned length, pos; | |
2657 | struct inode *inode = mapping->host; | |
1da177e4 | 2658 | struct page *page; |
03158cd7 NP |
2659 | struct buffer_head map_bh; |
2660 | int err; | |
1da177e4 | 2661 | |
03158cd7 NP |
2662 | blocksize = 1 << inode->i_blkbits; |
2663 | length = offset & (blocksize - 1); | |
2664 | ||
2665 | /* Block boundary? Nothing to do */ | |
2666 | if (!length) | |
2667 | return 0; | |
2668 | ||
2669 | length = blocksize - length; | |
2670 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
1da177e4 | 2671 | |
1da177e4 | 2672 | page = grab_cache_page(mapping, index); |
03158cd7 | 2673 | err = -ENOMEM; |
1da177e4 LT |
2674 | if (!page) |
2675 | goto out; | |
2676 | ||
03158cd7 NP |
2677 | if (page_has_buffers(page)) { |
2678 | has_buffers: | |
2679 | unlock_page(page); | |
2680 | page_cache_release(page); | |
2681 | return block_truncate_page(mapping, from, get_block); | |
2682 | } | |
2683 | ||
2684 | /* Find the buffer that contains "offset" */ | |
2685 | pos = blocksize; | |
2686 | while (offset >= pos) { | |
2687 | iblock++; | |
2688 | pos += blocksize; | |
2689 | } | |
2690 | ||
2691 | err = get_block(inode, iblock, &map_bh, 0); | |
2692 | if (err) | |
2693 | goto unlock; | |
2694 | /* unmapped? It's a hole - nothing to do */ | |
2695 | if (!buffer_mapped(&map_bh)) | |
2696 | goto unlock; | |
2697 | ||
2698 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2699 | if (!PageUptodate(page)) { | |
2700 | err = mapping->a_ops->readpage(NULL, page); | |
2701 | if (err) { | |
2702 | page_cache_release(page); | |
2703 | goto out; | |
2704 | } | |
2705 | lock_page(page); | |
2706 | if (!PageUptodate(page)) { | |
2707 | err = -EIO; | |
2708 | goto unlock; | |
2709 | } | |
2710 | if (page_has_buffers(page)) | |
2711 | goto has_buffers; | |
1da177e4 | 2712 | } |
03158cd7 NP |
2713 | zero_user_page(page, offset, length, KM_USER0); |
2714 | set_page_dirty(page); | |
2715 | err = 0; | |
2716 | ||
2717 | unlock: | |
1da177e4 LT |
2718 | unlock_page(page); |
2719 | page_cache_release(page); | |
2720 | out: | |
03158cd7 | 2721 | return err; |
1da177e4 LT |
2722 | } |
2723 | EXPORT_SYMBOL(nobh_truncate_page); | |
2724 | ||
2725 | int block_truncate_page(struct address_space *mapping, | |
2726 | loff_t from, get_block_t *get_block) | |
2727 | { | |
2728 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2729 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2730 | unsigned blocksize; | |
54b21a79 | 2731 | sector_t iblock; |
1da177e4 LT |
2732 | unsigned length, pos; |
2733 | struct inode *inode = mapping->host; | |
2734 | struct page *page; | |
2735 | struct buffer_head *bh; | |
1da177e4 LT |
2736 | int err; |
2737 | ||
2738 | blocksize = 1 << inode->i_blkbits; | |
2739 | length = offset & (blocksize - 1); | |
2740 | ||
2741 | /* Block boundary? Nothing to do */ | |
2742 | if (!length) | |
2743 | return 0; | |
2744 | ||
2745 | length = blocksize - length; | |
54b21a79 | 2746 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2747 | |
2748 | page = grab_cache_page(mapping, index); | |
2749 | err = -ENOMEM; | |
2750 | if (!page) | |
2751 | goto out; | |
2752 | ||
2753 | if (!page_has_buffers(page)) | |
2754 | create_empty_buffers(page, blocksize, 0); | |
2755 | ||
2756 | /* Find the buffer that contains "offset" */ | |
2757 | bh = page_buffers(page); | |
2758 | pos = blocksize; | |
2759 | while (offset >= pos) { | |
2760 | bh = bh->b_this_page; | |
2761 | iblock++; | |
2762 | pos += blocksize; | |
2763 | } | |
2764 | ||
2765 | err = 0; | |
2766 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2767 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2768 | err = get_block(inode, iblock, bh, 0); |
2769 | if (err) | |
2770 | goto unlock; | |
2771 | /* unmapped? It's a hole - nothing to do */ | |
2772 | if (!buffer_mapped(bh)) | |
2773 | goto unlock; | |
2774 | } | |
2775 | ||
2776 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2777 | if (PageUptodate(page)) | |
2778 | set_buffer_uptodate(bh); | |
2779 | ||
33a266dd | 2780 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
1da177e4 LT |
2781 | err = -EIO; |
2782 | ll_rw_block(READ, 1, &bh); | |
2783 | wait_on_buffer(bh); | |
2784 | /* Uhhuh. Read error. Complain and punt. */ | |
2785 | if (!buffer_uptodate(bh)) | |
2786 | goto unlock; | |
2787 | } | |
2788 | ||
01f2705d | 2789 | zero_user_page(page, offset, length, KM_USER0); |
1da177e4 LT |
2790 | mark_buffer_dirty(bh); |
2791 | err = 0; | |
2792 | ||
2793 | unlock: | |
2794 | unlock_page(page); | |
2795 | page_cache_release(page); | |
2796 | out: | |
2797 | return err; | |
2798 | } | |
2799 | ||
2800 | /* | |
2801 | * The generic ->writepage function for buffer-backed address_spaces | |
2802 | */ | |
2803 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2804 | struct writeback_control *wbc) | |
2805 | { | |
2806 | struct inode * const inode = page->mapping->host; | |
2807 | loff_t i_size = i_size_read(inode); | |
2808 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2809 | unsigned offset; | |
1da177e4 LT |
2810 | |
2811 | /* Is the page fully inside i_size? */ | |
2812 | if (page->index < end_index) | |
2813 | return __block_write_full_page(inode, page, get_block, wbc); | |
2814 | ||
2815 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2816 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2817 | if (page->index >= end_index+1 || !offset) { | |
2818 | /* | |
2819 | * The page may have dirty, unmapped buffers. For example, | |
2820 | * they may have been added in ext3_writepage(). Make them | |
2821 | * freeable here, so the page does not leak. | |
2822 | */ | |
aaa4059b | 2823 | do_invalidatepage(page, 0); |
1da177e4 LT |
2824 | unlock_page(page); |
2825 | return 0; /* don't care */ | |
2826 | } | |
2827 | ||
2828 | /* | |
2829 | * The page straddles i_size. It must be zeroed out on each and every | |
2830 | * writepage invokation because it may be mmapped. "A file is mapped | |
2831 | * in multiples of the page size. For a file that is not a multiple of | |
2832 | * the page size, the remaining memory is zeroed when mapped, and | |
2833 | * writes to that region are not written out to the file." | |
2834 | */ | |
01f2705d | 2835 | zero_user_page(page, offset, PAGE_CACHE_SIZE - offset, KM_USER0); |
1da177e4 LT |
2836 | return __block_write_full_page(inode, page, get_block, wbc); |
2837 | } | |
2838 | ||
2839 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, | |
2840 | get_block_t *get_block) | |
2841 | { | |
2842 | struct buffer_head tmp; | |
2843 | struct inode *inode = mapping->host; | |
2844 | tmp.b_state = 0; | |
2845 | tmp.b_blocknr = 0; | |
b0cf2321 | 2846 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2847 | get_block(inode, block, &tmp, 0); |
2848 | return tmp.b_blocknr; | |
2849 | } | |
2850 | ||
6712ecf8 | 2851 | static void end_bio_bh_io_sync(struct bio *bio, int err) |
1da177e4 LT |
2852 | { |
2853 | struct buffer_head *bh = bio->bi_private; | |
2854 | ||
1da177e4 LT |
2855 | if (err == -EOPNOTSUPP) { |
2856 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
2857 | set_bit(BH_Eopnotsupp, &bh->b_state); | |
2858 | } | |
2859 | ||
2860 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); | |
2861 | bio_put(bio); | |
1da177e4 LT |
2862 | } |
2863 | ||
2864 | int submit_bh(int rw, struct buffer_head * bh) | |
2865 | { | |
2866 | struct bio *bio; | |
2867 | int ret = 0; | |
2868 | ||
2869 | BUG_ON(!buffer_locked(bh)); | |
2870 | BUG_ON(!buffer_mapped(bh)); | |
2871 | BUG_ON(!bh->b_end_io); | |
2872 | ||
2873 | if (buffer_ordered(bh) && (rw == WRITE)) | |
2874 | rw = WRITE_BARRIER; | |
2875 | ||
2876 | /* | |
2877 | * Only clear out a write error when rewriting, should this | |
2878 | * include WRITE_SYNC as well? | |
2879 | */ | |
2880 | if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) | |
2881 | clear_buffer_write_io_error(bh); | |
2882 | ||
2883 | /* | |
2884 | * from here on down, it's all bio -- do the initial mapping, | |
2885 | * submit_bio -> generic_make_request may further map this bio around | |
2886 | */ | |
2887 | bio = bio_alloc(GFP_NOIO, 1); | |
2888 | ||
2889 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2890 | bio->bi_bdev = bh->b_bdev; | |
2891 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2892 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2893 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2894 | ||
2895 | bio->bi_vcnt = 1; | |
2896 | bio->bi_idx = 0; | |
2897 | bio->bi_size = bh->b_size; | |
2898 | ||
2899 | bio->bi_end_io = end_bio_bh_io_sync; | |
2900 | bio->bi_private = bh; | |
2901 | ||
2902 | bio_get(bio); | |
2903 | submit_bio(rw, bio); | |
2904 | ||
2905 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2906 | ret = -EOPNOTSUPP; | |
2907 | ||
2908 | bio_put(bio); | |
2909 | return ret; | |
2910 | } | |
2911 | ||
2912 | /** | |
2913 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
a7662236 | 2914 | * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) |
1da177e4 LT |
2915 | * @nr: number of &struct buffer_heads in the array |
2916 | * @bhs: array of pointers to &struct buffer_head | |
2917 | * | |
a7662236 JK |
2918 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
2919 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
2920 | * %SWRITE is like %WRITE only we make sure that the *current* data in buffers | |
2921 | * are sent to disk. The fourth %READA option is described in the documentation | |
2922 | * for generic_make_request() which ll_rw_block() calls. | |
1da177e4 LT |
2923 | * |
2924 | * This function drops any buffer that it cannot get a lock on (with the | |
a7662236 JK |
2925 | * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be |
2926 | * clean when doing a write request, and any buffer that appears to be | |
2927 | * up-to-date when doing read request. Further it marks as clean buffers that | |
2928 | * are processed for writing (the buffer cache won't assume that they are | |
2929 | * actually clean until the buffer gets unlocked). | |
1da177e4 LT |
2930 | * |
2931 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
2932 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
2933 | * any waiters. | |
2934 | * | |
2935 | * All of the buffers must be for the same device, and must also be a | |
2936 | * multiple of the current approved size for the device. | |
2937 | */ | |
2938 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
2939 | { | |
2940 | int i; | |
2941 | ||
2942 | for (i = 0; i < nr; i++) { | |
2943 | struct buffer_head *bh = bhs[i]; | |
2944 | ||
a7662236 JK |
2945 | if (rw == SWRITE) |
2946 | lock_buffer(bh); | |
2947 | else if (test_set_buffer_locked(bh)) | |
1da177e4 LT |
2948 | continue; |
2949 | ||
a7662236 | 2950 | if (rw == WRITE || rw == SWRITE) { |
1da177e4 | 2951 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 2952 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 2953 | get_bh(bh); |
1da177e4 LT |
2954 | submit_bh(WRITE, bh); |
2955 | continue; | |
2956 | } | |
2957 | } else { | |
1da177e4 | 2958 | if (!buffer_uptodate(bh)) { |
76c3073a | 2959 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 2960 | get_bh(bh); |
1da177e4 LT |
2961 | submit_bh(rw, bh); |
2962 | continue; | |
2963 | } | |
2964 | } | |
2965 | unlock_buffer(bh); | |
1da177e4 LT |
2966 | } |
2967 | } | |
2968 | ||
2969 | /* | |
2970 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
2971 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
2972 | * the buffer_head. | |
2973 | */ | |
2974 | int sync_dirty_buffer(struct buffer_head *bh) | |
2975 | { | |
2976 | int ret = 0; | |
2977 | ||
2978 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
2979 | lock_buffer(bh); | |
2980 | if (test_clear_buffer_dirty(bh)) { | |
2981 | get_bh(bh); | |
2982 | bh->b_end_io = end_buffer_write_sync; | |
2983 | ret = submit_bh(WRITE, bh); | |
2984 | wait_on_buffer(bh); | |
2985 | if (buffer_eopnotsupp(bh)) { | |
2986 | clear_buffer_eopnotsupp(bh); | |
2987 | ret = -EOPNOTSUPP; | |
2988 | } | |
2989 | if (!ret && !buffer_uptodate(bh)) | |
2990 | ret = -EIO; | |
2991 | } else { | |
2992 | unlock_buffer(bh); | |
2993 | } | |
2994 | return ret; | |
2995 | } | |
2996 | ||
2997 | /* | |
2998 | * try_to_free_buffers() checks if all the buffers on this particular page | |
2999 | * are unused, and releases them if so. | |
3000 | * | |
3001 | * Exclusion against try_to_free_buffers may be obtained by either | |
3002 | * locking the page or by holding its mapping's private_lock. | |
3003 | * | |
3004 | * If the page is dirty but all the buffers are clean then we need to | |
3005 | * be sure to mark the page clean as well. This is because the page | |
3006 | * may be against a block device, and a later reattachment of buffers | |
3007 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3008 | * filesystem data on the same device. | |
3009 | * | |
3010 | * The same applies to regular filesystem pages: if all the buffers are | |
3011 | * clean then we set the page clean and proceed. To do that, we require | |
3012 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3013 | * private_lock. | |
3014 | * | |
3015 | * try_to_free_buffers() is non-blocking. | |
3016 | */ | |
3017 | static inline int buffer_busy(struct buffer_head *bh) | |
3018 | { | |
3019 | return atomic_read(&bh->b_count) | | |
3020 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3021 | } | |
3022 | ||
3023 | static int | |
3024 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3025 | { | |
3026 | struct buffer_head *head = page_buffers(page); | |
3027 | struct buffer_head *bh; | |
3028 | ||
3029 | bh = head; | |
3030 | do { | |
de7d5a3b | 3031 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
3032 | set_bit(AS_EIO, &page->mapping->flags); |
3033 | if (buffer_busy(bh)) | |
3034 | goto failed; | |
3035 | bh = bh->b_this_page; | |
3036 | } while (bh != head); | |
3037 | ||
3038 | do { | |
3039 | struct buffer_head *next = bh->b_this_page; | |
3040 | ||
3041 | if (!list_empty(&bh->b_assoc_buffers)) | |
3042 | __remove_assoc_queue(bh); | |
3043 | bh = next; | |
3044 | } while (bh != head); | |
3045 | *buffers_to_free = head; | |
3046 | __clear_page_buffers(page); | |
3047 | return 1; | |
3048 | failed: | |
3049 | return 0; | |
3050 | } | |
3051 | ||
3052 | int try_to_free_buffers(struct page *page) | |
3053 | { | |
3054 | struct address_space * const mapping = page->mapping; | |
3055 | struct buffer_head *buffers_to_free = NULL; | |
3056 | int ret = 0; | |
3057 | ||
3058 | BUG_ON(!PageLocked(page)); | |
ecdfc978 | 3059 | if (PageWriteback(page)) |
1da177e4 LT |
3060 | return 0; |
3061 | ||
3062 | if (mapping == NULL) { /* can this still happen? */ | |
3063 | ret = drop_buffers(page, &buffers_to_free); | |
3064 | goto out; | |
3065 | } | |
3066 | ||
3067 | spin_lock(&mapping->private_lock); | |
3068 | ret = drop_buffers(page, &buffers_to_free); | |
ecdfc978 LT |
3069 | |
3070 | /* | |
3071 | * If the filesystem writes its buffers by hand (eg ext3) | |
3072 | * then we can have clean buffers against a dirty page. We | |
3073 | * clean the page here; otherwise the VM will never notice | |
3074 | * that the filesystem did any IO at all. | |
3075 | * | |
3076 | * Also, during truncate, discard_buffer will have marked all | |
3077 | * the page's buffers clean. We discover that here and clean | |
3078 | * the page also. | |
87df7241 NP |
3079 | * |
3080 | * private_lock must be held over this entire operation in order | |
3081 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3082 | * dirty bit from being lost. | |
ecdfc978 LT |
3083 | */ |
3084 | if (ret) | |
3085 | cancel_dirty_page(page, PAGE_CACHE_SIZE); | |
87df7241 | 3086 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
3087 | out: |
3088 | if (buffers_to_free) { | |
3089 | struct buffer_head *bh = buffers_to_free; | |
3090 | ||
3091 | do { | |
3092 | struct buffer_head *next = bh->b_this_page; | |
3093 | free_buffer_head(bh); | |
3094 | bh = next; | |
3095 | } while (bh != buffers_to_free); | |
3096 | } | |
3097 | return ret; | |
3098 | } | |
3099 | EXPORT_SYMBOL(try_to_free_buffers); | |
3100 | ||
3978d717 | 3101 | void block_sync_page(struct page *page) |
1da177e4 LT |
3102 | { |
3103 | struct address_space *mapping; | |
3104 | ||
3105 | smp_mb(); | |
3106 | mapping = page_mapping(page); | |
3107 | if (mapping) | |
3108 | blk_run_backing_dev(mapping->backing_dev_info, page); | |
1da177e4 LT |
3109 | } |
3110 | ||
3111 | /* | |
3112 | * There are no bdflush tunables left. But distributions are | |
3113 | * still running obsolete flush daemons, so we terminate them here. | |
3114 | * | |
3115 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
3116 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. | |
3117 | */ | |
3118 | asmlinkage long sys_bdflush(int func, long data) | |
3119 | { | |
3120 | static int msg_count; | |
3121 | ||
3122 | if (!capable(CAP_SYS_ADMIN)) | |
3123 | return -EPERM; | |
3124 | ||
3125 | if (msg_count < 5) { | |
3126 | msg_count++; | |
3127 | printk(KERN_INFO | |
3128 | "warning: process `%s' used the obsolete bdflush" | |
3129 | " system call\n", current->comm); | |
3130 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3131 | } | |
3132 | ||
3133 | if (func == 1) | |
3134 | do_exit(0); | |
3135 | return 0; | |
3136 | } | |
3137 | ||
3138 | /* | |
3139 | * Buffer-head allocation | |
3140 | */ | |
e18b890b | 3141 | static struct kmem_cache *bh_cachep; |
1da177e4 LT |
3142 | |
3143 | /* | |
3144 | * Once the number of bh's in the machine exceeds this level, we start | |
3145 | * stripping them in writeback. | |
3146 | */ | |
3147 | static int max_buffer_heads; | |
3148 | ||
3149 | int buffer_heads_over_limit; | |
3150 | ||
3151 | struct bh_accounting { | |
3152 | int nr; /* Number of live bh's */ | |
3153 | int ratelimit; /* Limit cacheline bouncing */ | |
3154 | }; | |
3155 | ||
3156 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3157 | ||
3158 | static void recalc_bh_state(void) | |
3159 | { | |
3160 | int i; | |
3161 | int tot = 0; | |
3162 | ||
3163 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) | |
3164 | return; | |
3165 | __get_cpu_var(bh_accounting).ratelimit = 0; | |
8a143426 | 3166 | for_each_online_cpu(i) |
1da177e4 LT |
3167 | tot += per_cpu(bh_accounting, i).nr; |
3168 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3169 | } | |
3170 | ||
dd0fc66f | 3171 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 | 3172 | { |
e12ba74d MG |
3173 | struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, |
3174 | set_migrateflags(gfp_flags, __GFP_RECLAIMABLE)); | |
1da177e4 | 3175 | if (ret) { |
a35afb83 | 3176 | INIT_LIST_HEAD(&ret->b_assoc_buffers); |
736c7b80 | 3177 | get_cpu_var(bh_accounting).nr++; |
1da177e4 | 3178 | recalc_bh_state(); |
736c7b80 | 3179 | put_cpu_var(bh_accounting); |
1da177e4 LT |
3180 | } |
3181 | return ret; | |
3182 | } | |
3183 | EXPORT_SYMBOL(alloc_buffer_head); | |
3184 | ||
3185 | void free_buffer_head(struct buffer_head *bh) | |
3186 | { | |
3187 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3188 | kmem_cache_free(bh_cachep, bh); | |
736c7b80 | 3189 | get_cpu_var(bh_accounting).nr--; |
1da177e4 | 3190 | recalc_bh_state(); |
736c7b80 | 3191 | put_cpu_var(bh_accounting); |
1da177e4 LT |
3192 | } |
3193 | EXPORT_SYMBOL(free_buffer_head); | |
3194 | ||
1da177e4 LT |
3195 | static void buffer_exit_cpu(int cpu) |
3196 | { | |
3197 | int i; | |
3198 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3199 | ||
3200 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3201 | brelse(b->bhs[i]); | |
3202 | b->bhs[i] = NULL; | |
3203 | } | |
8a143426 ED |
3204 | get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; |
3205 | per_cpu(bh_accounting, cpu).nr = 0; | |
3206 | put_cpu_var(bh_accounting); | |
1da177e4 LT |
3207 | } |
3208 | ||
3209 | static int buffer_cpu_notify(struct notifier_block *self, | |
3210 | unsigned long action, void *hcpu) | |
3211 | { | |
8bb78442 | 3212 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) |
1da177e4 LT |
3213 | buffer_exit_cpu((unsigned long)hcpu); |
3214 | return NOTIFY_OK; | |
3215 | } | |
1da177e4 LT |
3216 | |
3217 | void __init buffer_init(void) | |
3218 | { | |
3219 | int nrpages; | |
3220 | ||
a35afb83 CL |
3221 | bh_cachep = KMEM_CACHE(buffer_head, |
3222 | SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|SLAB_MEM_SPREAD); | |
1da177e4 LT |
3223 | |
3224 | /* | |
3225 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3226 | */ | |
3227 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3228 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3229 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3230 | } | |
3231 | ||
3232 | EXPORT_SYMBOL(__bforget); | |
3233 | EXPORT_SYMBOL(__brelse); | |
3234 | EXPORT_SYMBOL(__wait_on_buffer); | |
3235 | EXPORT_SYMBOL(block_commit_write); | |
3236 | EXPORT_SYMBOL(block_prepare_write); | |
54171690 | 3237 | EXPORT_SYMBOL(block_page_mkwrite); |
1da177e4 LT |
3238 | EXPORT_SYMBOL(block_read_full_page); |
3239 | EXPORT_SYMBOL(block_sync_page); | |
3240 | EXPORT_SYMBOL(block_truncate_page); | |
3241 | EXPORT_SYMBOL(block_write_full_page); | |
89e10787 | 3242 | EXPORT_SYMBOL(cont_write_begin); |
1da177e4 LT |
3243 | EXPORT_SYMBOL(end_buffer_read_sync); |
3244 | EXPORT_SYMBOL(end_buffer_write_sync); | |
3245 | EXPORT_SYMBOL(file_fsync); | |
3246 | EXPORT_SYMBOL(fsync_bdev); | |
3247 | EXPORT_SYMBOL(generic_block_bmap); | |
3248 | EXPORT_SYMBOL(generic_commit_write); | |
05eb0b51 | 3249 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 LT |
3250 | EXPORT_SYMBOL(init_buffer); |
3251 | EXPORT_SYMBOL(invalidate_bdev); | |
3252 | EXPORT_SYMBOL(ll_rw_block); | |
3253 | EXPORT_SYMBOL(mark_buffer_dirty); | |
3254 | EXPORT_SYMBOL(submit_bh); | |
3255 | EXPORT_SYMBOL(sync_dirty_buffer); | |
3256 | EXPORT_SYMBOL(unlock_buffer); |