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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/fs/buffer.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 2002 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95 | |
9 | * | |
10 | * Removed a lot of unnecessary code and simplified things now that | |
11 | * the buffer cache isn't our primary cache - Andrew Tridgell 12/96 | |
12 | * | |
13 | * Speed up hash, lru, and free list operations. Use gfp() for allocating | |
14 | * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM | |
15 | * | |
16 | * Added 32k buffer block sizes - these are required older ARM systems. - RMK | |
17 | * | |
18 | * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de> | |
19 | */ | |
20 | ||
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 | ||
fc9b52cd | 70 | void __lock_buffer(struct buffer_head *bh) |
1da177e4 LT |
71 | { |
72 | wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, | |
73 | TASK_UNINTERRUPTIBLE); | |
74 | } | |
75 | EXPORT_SYMBOL(__lock_buffer); | |
76 | ||
fc9b52cd | 77 | void unlock_buffer(struct buffer_head *bh) |
1da177e4 | 78 | { |
51b07fc3 | 79 | clear_bit_unlock(BH_Lock, &bh->b_state); |
1da177e4 LT |
80 | smp_mb__after_clear_bit(); |
81 | wake_up_bit(&bh->b_state, BH_Lock); | |
82 | } | |
83 | ||
84 | /* | |
85 | * Block until a buffer comes unlocked. This doesn't stop it | |
86 | * from becoming locked again - you have to lock it yourself | |
87 | * if you want to preserve its state. | |
88 | */ | |
89 | void __wait_on_buffer(struct buffer_head * bh) | |
90 | { | |
91 | wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); | |
92 | } | |
93 | ||
94 | static void | |
95 | __clear_page_buffers(struct page *page) | |
96 | { | |
97 | ClearPagePrivate(page); | |
4c21e2f2 | 98 | set_page_private(page, 0); |
1da177e4 LT |
99 | page_cache_release(page); |
100 | } | |
101 | ||
08bafc03 KM |
102 | |
103 | static int quiet_error(struct buffer_head *bh) | |
104 | { | |
105 | if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit()) | |
106 | return 0; | |
107 | return 1; | |
108 | } | |
109 | ||
110 | ||
1da177e4 LT |
111 | static void buffer_io_error(struct buffer_head *bh) |
112 | { | |
113 | char b[BDEVNAME_SIZE]; | |
1da177e4 LT |
114 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", |
115 | bdevname(bh->b_bdev, b), | |
116 | (unsigned long long)bh->b_blocknr); | |
117 | } | |
118 | ||
119 | /* | |
68671f35 DM |
120 | * End-of-IO handler helper function which does not touch the bh after |
121 | * unlocking it. | |
122 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
123 | * a race there is benign: unlock_buffer() only use the bh's address for | |
124 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
125 | * itself. | |
1da177e4 | 126 | */ |
68671f35 | 127 | static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
128 | { |
129 | if (uptodate) { | |
130 | set_buffer_uptodate(bh); | |
131 | } else { | |
132 | /* This happens, due to failed READA attempts. */ | |
133 | clear_buffer_uptodate(bh); | |
134 | } | |
135 | unlock_buffer(bh); | |
68671f35 DM |
136 | } |
137 | ||
138 | /* | |
139 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
140 | * unlock the buffer. This is what ll_rw_block uses too. | |
141 | */ | |
142 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
143 | { | |
144 | __end_buffer_read_notouch(bh, uptodate); | |
1da177e4 LT |
145 | put_bh(bh); |
146 | } | |
147 | ||
148 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
149 | { | |
150 | char b[BDEVNAME_SIZE]; | |
151 | ||
152 | if (uptodate) { | |
153 | set_buffer_uptodate(bh); | |
154 | } else { | |
08bafc03 | 155 | if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) { |
1da177e4 LT |
156 | buffer_io_error(bh); |
157 | printk(KERN_WARNING "lost page write due to " | |
158 | "I/O error on %s\n", | |
159 | bdevname(bh->b_bdev, b)); | |
160 | } | |
161 | set_buffer_write_io_error(bh); | |
162 | clear_buffer_uptodate(bh); | |
163 | } | |
164 | unlock_buffer(bh); | |
165 | put_bh(bh); | |
166 | } | |
167 | ||
1da177e4 LT |
168 | /* |
169 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
170 | * But it's the page lock which protects the buffers. To get around this, | |
171 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
172 | * private_lock. | |
173 | * | |
174 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
175 | * may be quite high. This code could TryLock the page, and if that | |
176 | * succeeds, there is no need to take private_lock. (But if | |
177 | * private_lock is contended then so is mapping->tree_lock). | |
178 | */ | |
179 | static struct buffer_head * | |
385fd4c5 | 180 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
181 | { |
182 | struct inode *bd_inode = bdev->bd_inode; | |
183 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
184 | struct buffer_head *ret = NULL; | |
185 | pgoff_t index; | |
186 | struct buffer_head *bh; | |
187 | struct buffer_head *head; | |
188 | struct page *page; | |
189 | int all_mapped = 1; | |
190 | ||
191 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
192 | page = find_get_page(bd_mapping, index); | |
193 | if (!page) | |
194 | goto out; | |
195 | ||
196 | spin_lock(&bd_mapping->private_lock); | |
197 | if (!page_has_buffers(page)) | |
198 | goto out_unlock; | |
199 | head = page_buffers(page); | |
200 | bh = head; | |
201 | do { | |
97f76d3d NK |
202 | if (!buffer_mapped(bh)) |
203 | all_mapped = 0; | |
204 | else if (bh->b_blocknr == block) { | |
1da177e4 LT |
205 | ret = bh; |
206 | get_bh(bh); | |
207 | goto out_unlock; | |
208 | } | |
1da177e4 LT |
209 | bh = bh->b_this_page; |
210 | } while (bh != head); | |
211 | ||
212 | /* we might be here because some of the buffers on this page are | |
213 | * not mapped. This is due to various races between | |
214 | * file io on the block device and getblk. It gets dealt with | |
215 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
216 | */ | |
217 | if (all_mapped) { | |
218 | printk("__find_get_block_slow() failed. " | |
219 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
220 | (unsigned long long)block, |
221 | (unsigned long long)bh->b_blocknr); | |
222 | printk("b_state=0x%08lx, b_size=%zu\n", | |
223 | bh->b_state, bh->b_size); | |
1da177e4 LT |
224 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
225 | } | |
226 | out_unlock: | |
227 | spin_unlock(&bd_mapping->private_lock); | |
228 | page_cache_release(page); | |
229 | out: | |
230 | return ret; | |
231 | } | |
232 | ||
233 | /* If invalidate_buffers() will trash dirty buffers, it means some kind | |
234 | of fs corruption is going on. Trashing dirty data always imply losing | |
235 | information that was supposed to be just stored on the physical layer | |
236 | by the user. | |
237 | ||
238 | Thus invalidate_buffers in general usage is not allwowed to trash | |
239 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to | |
240 | be preserved. These buffers are simply skipped. | |
241 | ||
242 | We also skip buffers which are still in use. For example this can | |
243 | happen if a userspace program is reading the block device. | |
244 | ||
245 | NOTE: In the case where the user removed a removable-media-disk even if | |
246 | there's still dirty data not synced on disk (due a bug in the device driver | |
247 | or due an error of the user), by not destroying the dirty buffers we could | |
248 | generate corruption also on the next media inserted, thus a parameter is | |
249 | necessary to handle this case in the most safe way possible (trying | |
250 | to not corrupt also the new disk inserted with the data belonging to | |
251 | the old now corrupted disk). Also for the ramdisk the natural thing | |
252 | to do in order to release the ramdisk memory is to destroy dirty buffers. | |
253 | ||
254 | These are two special cases. Normal usage imply the device driver | |
255 | to issue a sync on the device (without waiting I/O completion) and | |
256 | then an invalidate_buffers call that doesn't trash dirty buffers. | |
257 | ||
258 | For handling cache coherency with the blkdev pagecache the 'update' case | |
259 | is been introduced. It is needed to re-read from disk any pinned | |
260 | buffer. NOTE: re-reading from disk is destructive so we can do it only | |
261 | when we assume nobody is changing the buffercache under our I/O and when | |
262 | we think the disk contains more recent information than the buffercache. | |
263 | The update == 1 pass marks the buffers we need to update, the update == 2 | |
264 | pass does the actual I/O. */ | |
f98393a6 | 265 | void invalidate_bdev(struct block_device *bdev) |
1da177e4 | 266 | { |
0e1dfc66 AM |
267 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
268 | ||
269 | if (mapping->nrpages == 0) | |
270 | return; | |
271 | ||
1da177e4 | 272 | invalidate_bh_lrus(); |
fc0ecff6 | 273 | invalidate_mapping_pages(mapping, 0, -1); |
1da177e4 LT |
274 | } |
275 | ||
276 | /* | |
277 | * Kick pdflush then try to free up some ZONE_NORMAL memory. | |
278 | */ | |
279 | static void free_more_memory(void) | |
280 | { | |
19770b32 | 281 | struct zone *zone; |
0e88460d | 282 | int nid; |
1da177e4 | 283 | |
687a21ce | 284 | wakeup_pdflush(1024); |
1da177e4 LT |
285 | yield(); |
286 | ||
0e88460d | 287 | for_each_online_node(nid) { |
19770b32 MG |
288 | (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS), |
289 | gfp_zone(GFP_NOFS), NULL, | |
290 | &zone); | |
291 | if (zone) | |
54a6eb5c | 292 | try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0, |
327c0e96 | 293 | GFP_NOFS, NULL); |
1da177e4 LT |
294 | } |
295 | } | |
296 | ||
297 | /* | |
298 | * I/O completion handler for block_read_full_page() - pages | |
299 | * which come unlocked at the end of I/O. | |
300 | */ | |
301 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
302 | { | |
1da177e4 | 303 | unsigned long flags; |
a3972203 | 304 | struct buffer_head *first; |
1da177e4 LT |
305 | struct buffer_head *tmp; |
306 | struct page *page; | |
307 | int page_uptodate = 1; | |
308 | ||
309 | BUG_ON(!buffer_async_read(bh)); | |
310 | ||
311 | page = bh->b_page; | |
312 | if (uptodate) { | |
313 | set_buffer_uptodate(bh); | |
314 | } else { | |
315 | clear_buffer_uptodate(bh); | |
08bafc03 | 316 | if (!quiet_error(bh)) |
1da177e4 LT |
317 | buffer_io_error(bh); |
318 | SetPageError(page); | |
319 | } | |
320 | ||
321 | /* | |
322 | * Be _very_ careful from here on. Bad things can happen if | |
323 | * two buffer heads end IO at almost the same time and both | |
324 | * decide that the page is now completely done. | |
325 | */ | |
a3972203 NP |
326 | first = page_buffers(page); |
327 | local_irq_save(flags); | |
328 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
329 | clear_buffer_async_read(bh); |
330 | unlock_buffer(bh); | |
331 | tmp = bh; | |
332 | do { | |
333 | if (!buffer_uptodate(tmp)) | |
334 | page_uptodate = 0; | |
335 | if (buffer_async_read(tmp)) { | |
336 | BUG_ON(!buffer_locked(tmp)); | |
337 | goto still_busy; | |
338 | } | |
339 | tmp = tmp->b_this_page; | |
340 | } while (tmp != bh); | |
a3972203 NP |
341 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
342 | local_irq_restore(flags); | |
1da177e4 LT |
343 | |
344 | /* | |
345 | * If none of the buffers had errors and they are all | |
346 | * uptodate then we can set the page uptodate. | |
347 | */ | |
348 | if (page_uptodate && !PageError(page)) | |
349 | SetPageUptodate(page); | |
350 | unlock_page(page); | |
351 | return; | |
352 | ||
353 | still_busy: | |
a3972203 NP |
354 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
355 | local_irq_restore(flags); | |
1da177e4 LT |
356 | return; |
357 | } | |
358 | ||
359 | /* | |
360 | * Completion handler for block_write_full_page() - pages which are unlocked | |
361 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
362 | */ | |
b6cd0b77 | 363 | static void end_buffer_async_write(struct buffer_head *bh, int uptodate) |
1da177e4 LT |
364 | { |
365 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 366 | unsigned long flags; |
a3972203 | 367 | struct buffer_head *first; |
1da177e4 LT |
368 | struct buffer_head *tmp; |
369 | struct page *page; | |
370 | ||
371 | BUG_ON(!buffer_async_write(bh)); | |
372 | ||
373 | page = bh->b_page; | |
374 | if (uptodate) { | |
375 | set_buffer_uptodate(bh); | |
376 | } else { | |
08bafc03 | 377 | if (!quiet_error(bh)) { |
1da177e4 LT |
378 | buffer_io_error(bh); |
379 | printk(KERN_WARNING "lost page write due to " | |
380 | "I/O error on %s\n", | |
381 | bdevname(bh->b_bdev, b)); | |
382 | } | |
383 | set_bit(AS_EIO, &page->mapping->flags); | |
58ff407b | 384 | set_buffer_write_io_error(bh); |
1da177e4 LT |
385 | clear_buffer_uptodate(bh); |
386 | SetPageError(page); | |
387 | } | |
388 | ||
a3972203 NP |
389 | first = page_buffers(page); |
390 | local_irq_save(flags); | |
391 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
392 | ||
1da177e4 LT |
393 | clear_buffer_async_write(bh); |
394 | unlock_buffer(bh); | |
395 | tmp = bh->b_this_page; | |
396 | while (tmp != bh) { | |
397 | if (buffer_async_write(tmp)) { | |
398 | BUG_ON(!buffer_locked(tmp)); | |
399 | goto still_busy; | |
400 | } | |
401 | tmp = tmp->b_this_page; | |
402 | } | |
a3972203 NP |
403 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
404 | local_irq_restore(flags); | |
1da177e4 LT |
405 | end_page_writeback(page); |
406 | return; | |
407 | ||
408 | still_busy: | |
a3972203 NP |
409 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
410 | local_irq_restore(flags); | |
1da177e4 LT |
411 | return; |
412 | } | |
413 | ||
414 | /* | |
415 | * If a page's buffers are under async readin (end_buffer_async_read | |
416 | * completion) then there is a possibility that another thread of | |
417 | * control could lock one of the buffers after it has completed | |
418 | * but while some of the other buffers have not completed. This | |
419 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
420 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
421 | * that this buffer is not under async I/O. | |
422 | * | |
423 | * The page comes unlocked when it has no locked buffer_async buffers | |
424 | * left. | |
425 | * | |
426 | * PageLocked prevents anyone starting new async I/O reads any of | |
427 | * the buffers. | |
428 | * | |
429 | * PageWriteback is used to prevent simultaneous writeout of the same | |
430 | * page. | |
431 | * | |
432 | * PageLocked prevents anyone from starting writeback of a page which is | |
433 | * under read I/O (PageWriteback is only ever set against a locked page). | |
434 | */ | |
435 | static void mark_buffer_async_read(struct buffer_head *bh) | |
436 | { | |
437 | bh->b_end_io = end_buffer_async_read; | |
438 | set_buffer_async_read(bh); | |
439 | } | |
440 | ||
441 | void mark_buffer_async_write(struct buffer_head *bh) | |
442 | { | |
443 | bh->b_end_io = end_buffer_async_write; | |
444 | set_buffer_async_write(bh); | |
445 | } | |
446 | EXPORT_SYMBOL(mark_buffer_async_write); | |
447 | ||
448 | ||
449 | /* | |
450 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
451 | * fsync functions. A common requirement for buffer-based filesystems is | |
452 | * that certain data from the backing blockdev needs to be written out for | |
453 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
454 | * written back and waited upon before fsync() returns. | |
455 | * | |
456 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
457 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
458 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
459 | * | |
460 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
461 | * from their controlling inode's queue when they are being freed. But | |
462 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
463 | * at the time, not against the S_ISREG file which depends on those buffers. | |
464 | * So the locking for private_list is via the private_lock in the address_space | |
465 | * which backs the buffers. Which is different from the address_space | |
466 | * against which the buffers are listed. So for a particular address_space, | |
467 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
468 | * mapping->private_list will always be protected by the backing blockdev's | |
469 | * ->private_lock. | |
470 | * | |
471 | * Which introduces a requirement: all buffers on an address_space's | |
472 | * ->private_list must be from the same address_space: the blockdev's. | |
473 | * | |
474 | * address_spaces which do not place buffers at ->private_list via these | |
475 | * utility functions are free to use private_lock and private_list for | |
476 | * whatever they want. The only requirement is that list_empty(private_list) | |
477 | * be true at clear_inode() time. | |
478 | * | |
479 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
480 | * filesystems should do that. invalidate_inode_buffers() should just go | |
481 | * BUG_ON(!list_empty). | |
482 | * | |
483 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
484 | * take an address_space, not an inode. And it should be called | |
485 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
486 | * queued up. | |
487 | * | |
488 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
489 | * list if it is already on a list. Because if the buffer is on a list, | |
490 | * it *must* already be on the right one. If not, the filesystem is being | |
491 | * silly. This will save a ton of locking. But first we have to ensure | |
492 | * that buffers are taken *off* the old inode's list when they are freed | |
493 | * (presumably in truncate). That requires careful auditing of all | |
494 | * filesystems (do it inside bforget()). It could also be done by bringing | |
495 | * b_inode back. | |
496 | */ | |
497 | ||
498 | /* | |
499 | * The buffer's backing address_space's private_lock must be held | |
500 | */ | |
dbacefc9 | 501 | static void __remove_assoc_queue(struct buffer_head *bh) |
1da177e4 LT |
502 | { |
503 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b JK |
504 | WARN_ON(!bh->b_assoc_map); |
505 | if (buffer_write_io_error(bh)) | |
506 | set_bit(AS_EIO, &bh->b_assoc_map->flags); | |
507 | bh->b_assoc_map = NULL; | |
1da177e4 LT |
508 | } |
509 | ||
510 | int inode_has_buffers(struct inode *inode) | |
511 | { | |
512 | return !list_empty(&inode->i_data.private_list); | |
513 | } | |
514 | ||
515 | /* | |
516 | * osync is designed to support O_SYNC io. It waits synchronously for | |
517 | * all already-submitted IO to complete, but does not queue any new | |
518 | * writes to the disk. | |
519 | * | |
520 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
521 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
522 | * completion. Any other dirty buffers which are not yet queued for | |
523 | * write will not be flushed to disk by the osync. | |
524 | */ | |
525 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
526 | { | |
527 | struct buffer_head *bh; | |
528 | struct list_head *p; | |
529 | int err = 0; | |
530 | ||
531 | spin_lock(lock); | |
532 | repeat: | |
533 | list_for_each_prev(p, list) { | |
534 | bh = BH_ENTRY(p); | |
535 | if (buffer_locked(bh)) { | |
536 | get_bh(bh); | |
537 | spin_unlock(lock); | |
538 | wait_on_buffer(bh); | |
539 | if (!buffer_uptodate(bh)) | |
540 | err = -EIO; | |
541 | brelse(bh); | |
542 | spin_lock(lock); | |
543 | goto repeat; | |
544 | } | |
545 | } | |
546 | spin_unlock(lock); | |
547 | return err; | |
548 | } | |
549 | ||
c2d75438 ES |
550 | void do_thaw_all(unsigned long unused) |
551 | { | |
552 | struct super_block *sb; | |
553 | char b[BDEVNAME_SIZE]; | |
554 | ||
555 | spin_lock(&sb_lock); | |
556 | restart: | |
557 | list_for_each_entry(sb, &super_blocks, s_list) { | |
558 | sb->s_count++; | |
559 | spin_unlock(&sb_lock); | |
560 | down_read(&sb->s_umount); | |
561 | while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb)) | |
562 | printk(KERN_WARNING "Emergency Thaw on %s\n", | |
563 | bdevname(sb->s_bdev, b)); | |
564 | up_read(&sb->s_umount); | |
565 | spin_lock(&sb_lock); | |
566 | if (__put_super_and_need_restart(sb)) | |
567 | goto restart; | |
568 | } | |
569 | spin_unlock(&sb_lock); | |
570 | printk(KERN_WARNING "Emergency Thaw complete\n"); | |
571 | } | |
572 | ||
573 | /** | |
574 | * emergency_thaw_all -- forcibly thaw every frozen filesystem | |
575 | * | |
576 | * Used for emergency unfreeze of all filesystems via SysRq | |
577 | */ | |
578 | void emergency_thaw_all(void) | |
579 | { | |
580 | pdflush_operation(do_thaw_all, 0); | |
581 | } | |
582 | ||
1da177e4 | 583 | /** |
78a4a50a | 584 | * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers |
67be2dd1 | 585 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
586 | * |
587 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
588 | * that I/O. | |
589 | * | |
67be2dd1 MW |
590 | * Basically, this is a convenience function for fsync(). |
591 | * @mapping is a file or directory which needs those buffers to be written for | |
592 | * a successful fsync(). | |
1da177e4 LT |
593 | */ |
594 | int sync_mapping_buffers(struct address_space *mapping) | |
595 | { | |
596 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
597 | ||
598 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
599 | return 0; | |
600 | ||
601 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
602 | &mapping->private_list); | |
603 | } | |
604 | EXPORT_SYMBOL(sync_mapping_buffers); | |
605 | ||
606 | /* | |
607 | * Called when we've recently written block `bblock', and it is known that | |
608 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
609 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
610 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
611 | */ | |
612 | void write_boundary_block(struct block_device *bdev, | |
613 | sector_t bblock, unsigned blocksize) | |
614 | { | |
615 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
616 | if (bh) { | |
617 | if (buffer_dirty(bh)) | |
618 | ll_rw_block(WRITE, 1, &bh); | |
619 | put_bh(bh); | |
620 | } | |
621 | } | |
622 | ||
623 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
624 | { | |
625 | struct address_space *mapping = inode->i_mapping; | |
626 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
627 | ||
628 | mark_buffer_dirty(bh); | |
629 | if (!mapping->assoc_mapping) { | |
630 | mapping->assoc_mapping = buffer_mapping; | |
631 | } else { | |
e827f923 | 632 | BUG_ON(mapping->assoc_mapping != buffer_mapping); |
1da177e4 | 633 | } |
535ee2fb | 634 | if (!bh->b_assoc_map) { |
1da177e4 LT |
635 | spin_lock(&buffer_mapping->private_lock); |
636 | list_move_tail(&bh->b_assoc_buffers, | |
637 | &mapping->private_list); | |
58ff407b | 638 | bh->b_assoc_map = mapping; |
1da177e4 LT |
639 | spin_unlock(&buffer_mapping->private_lock); |
640 | } | |
641 | } | |
642 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
643 | ||
787d2214 NP |
644 | /* |
645 | * Mark the page dirty, and set it dirty in the radix tree, and mark the inode | |
646 | * dirty. | |
647 | * | |
648 | * If warn is true, then emit a warning if the page is not uptodate and has | |
649 | * not been truncated. | |
650 | */ | |
a8e7d49a | 651 | static void __set_page_dirty(struct page *page, |
787d2214 NP |
652 | struct address_space *mapping, int warn) |
653 | { | |
19fd6231 | 654 | spin_lock_irq(&mapping->tree_lock); |
787d2214 NP |
655 | if (page->mapping) { /* Race with truncate? */ |
656 | WARN_ON_ONCE(warn && !PageUptodate(page)); | |
e3a7cca1 | 657 | account_page_dirtied(page, mapping); |
787d2214 NP |
658 | radix_tree_tag_set(&mapping->page_tree, |
659 | page_index(page), PAGECACHE_TAG_DIRTY); | |
660 | } | |
19fd6231 | 661 | spin_unlock_irq(&mapping->tree_lock); |
787d2214 | 662 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); |
787d2214 NP |
663 | } |
664 | ||
1da177e4 LT |
665 | /* |
666 | * Add a page to the dirty page list. | |
667 | * | |
668 | * It is a sad fact of life that this function is called from several places | |
669 | * deeply under spinlocking. It may not sleep. | |
670 | * | |
671 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
672 | * dirty-state coherency between the page and the buffers. It the page does | |
673 | * not have buffers then when they are later attached they will all be set | |
674 | * dirty. | |
675 | * | |
676 | * The buffers are dirtied before the page is dirtied. There's a small race | |
677 | * window in which a writepage caller may see the page cleanness but not the | |
678 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
679 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
680 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
681 | * page on the dirty page list. | |
682 | * | |
683 | * We use private_lock to lock against try_to_free_buffers while using the | |
684 | * page's buffer list. Also use this to protect against clean buffers being | |
685 | * added to the page after it was set dirty. | |
686 | * | |
687 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
688 | * address_space though. | |
689 | */ | |
690 | int __set_page_dirty_buffers(struct page *page) | |
691 | { | |
a8e7d49a | 692 | int newly_dirty; |
787d2214 | 693 | struct address_space *mapping = page_mapping(page); |
ebf7a227 NP |
694 | |
695 | if (unlikely(!mapping)) | |
696 | return !TestSetPageDirty(page); | |
1da177e4 LT |
697 | |
698 | spin_lock(&mapping->private_lock); | |
699 | if (page_has_buffers(page)) { | |
700 | struct buffer_head *head = page_buffers(page); | |
701 | struct buffer_head *bh = head; | |
702 | ||
703 | do { | |
704 | set_buffer_dirty(bh); | |
705 | bh = bh->b_this_page; | |
706 | } while (bh != head); | |
707 | } | |
a8e7d49a | 708 | newly_dirty = !TestSetPageDirty(page); |
1da177e4 LT |
709 | spin_unlock(&mapping->private_lock); |
710 | ||
a8e7d49a LT |
711 | if (newly_dirty) |
712 | __set_page_dirty(page, mapping, 1); | |
713 | return newly_dirty; | |
1da177e4 LT |
714 | } |
715 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
716 | ||
717 | /* | |
718 | * Write out and wait upon a list of buffers. | |
719 | * | |
720 | * We have conflicting pressures: we want to make sure that all | |
721 | * initially dirty buffers get waited on, but that any subsequently | |
722 | * dirtied buffers don't. After all, we don't want fsync to last | |
723 | * forever if somebody is actively writing to the file. | |
724 | * | |
725 | * Do this in two main stages: first we copy dirty buffers to a | |
726 | * temporary inode list, queueing the writes as we go. Then we clean | |
727 | * up, waiting for those writes to complete. | |
728 | * | |
729 | * During this second stage, any subsequent updates to the file may end | |
730 | * up refiling the buffer on the original inode's dirty list again, so | |
731 | * there is a chance we will end up with a buffer queued for write but | |
732 | * not yet completed on that list. So, as a final cleanup we go through | |
733 | * the osync code to catch these locked, dirty buffers without requeuing | |
734 | * any newly dirty buffers for write. | |
735 | */ | |
736 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
737 | { | |
738 | struct buffer_head *bh; | |
739 | struct list_head tmp; | |
535ee2fb | 740 | struct address_space *mapping; |
1da177e4 LT |
741 | int err = 0, err2; |
742 | ||
743 | INIT_LIST_HEAD(&tmp); | |
744 | ||
745 | spin_lock(lock); | |
746 | while (!list_empty(list)) { | |
747 | bh = BH_ENTRY(list->next); | |
535ee2fb | 748 | mapping = bh->b_assoc_map; |
58ff407b | 749 | __remove_assoc_queue(bh); |
535ee2fb JK |
750 | /* Avoid race with mark_buffer_dirty_inode() which does |
751 | * a lockless check and we rely on seeing the dirty bit */ | |
752 | smp_mb(); | |
1da177e4 LT |
753 | if (buffer_dirty(bh) || buffer_locked(bh)) { |
754 | list_add(&bh->b_assoc_buffers, &tmp); | |
535ee2fb | 755 | bh->b_assoc_map = mapping; |
1da177e4 LT |
756 | if (buffer_dirty(bh)) { |
757 | get_bh(bh); | |
758 | spin_unlock(lock); | |
759 | /* | |
760 | * Ensure any pending I/O completes so that | |
761 | * ll_rw_block() actually writes the current | |
762 | * contents - it is a noop if I/O is still in | |
763 | * flight on potentially older contents. | |
764 | */ | |
18ce3751 | 765 | ll_rw_block(SWRITE_SYNC, 1, &bh); |
1da177e4 LT |
766 | brelse(bh); |
767 | spin_lock(lock); | |
768 | } | |
769 | } | |
770 | } | |
771 | ||
772 | while (!list_empty(&tmp)) { | |
773 | bh = BH_ENTRY(tmp.prev); | |
1da177e4 | 774 | get_bh(bh); |
535ee2fb JK |
775 | mapping = bh->b_assoc_map; |
776 | __remove_assoc_queue(bh); | |
777 | /* Avoid race with mark_buffer_dirty_inode() which does | |
778 | * a lockless check and we rely on seeing the dirty bit */ | |
779 | smp_mb(); | |
780 | if (buffer_dirty(bh)) { | |
781 | list_add(&bh->b_assoc_buffers, | |
e3892296 | 782 | &mapping->private_list); |
535ee2fb JK |
783 | bh->b_assoc_map = mapping; |
784 | } | |
1da177e4 LT |
785 | spin_unlock(lock); |
786 | wait_on_buffer(bh); | |
787 | if (!buffer_uptodate(bh)) | |
788 | err = -EIO; | |
789 | brelse(bh); | |
790 | spin_lock(lock); | |
791 | } | |
792 | ||
793 | spin_unlock(lock); | |
794 | err2 = osync_buffers_list(lock, list); | |
795 | if (err) | |
796 | return err; | |
797 | else | |
798 | return err2; | |
799 | } | |
800 | ||
801 | /* | |
802 | * Invalidate any and all dirty buffers on a given inode. We are | |
803 | * probably unmounting the fs, but that doesn't mean we have already | |
804 | * done a sync(). Just drop the buffers from the inode list. | |
805 | * | |
806 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
807 | * assumes that all the buffers are against the blockdev. Not true | |
808 | * for reiserfs. | |
809 | */ | |
810 | void invalidate_inode_buffers(struct inode *inode) | |
811 | { | |
812 | if (inode_has_buffers(inode)) { | |
813 | struct address_space *mapping = &inode->i_data; | |
814 | struct list_head *list = &mapping->private_list; | |
815 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
816 | ||
817 | spin_lock(&buffer_mapping->private_lock); | |
818 | while (!list_empty(list)) | |
819 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
820 | spin_unlock(&buffer_mapping->private_lock); | |
821 | } | |
822 | } | |
52b19ac9 | 823 | EXPORT_SYMBOL(invalidate_inode_buffers); |
1da177e4 LT |
824 | |
825 | /* | |
826 | * Remove any clean buffers from the inode's buffer list. This is called | |
827 | * when we're trying to free the inode itself. Those buffers can pin it. | |
828 | * | |
829 | * Returns true if all buffers were removed. | |
830 | */ | |
831 | int remove_inode_buffers(struct inode *inode) | |
832 | { | |
833 | int ret = 1; | |
834 | ||
835 | if (inode_has_buffers(inode)) { | |
836 | struct address_space *mapping = &inode->i_data; | |
837 | struct list_head *list = &mapping->private_list; | |
838 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
839 | ||
840 | spin_lock(&buffer_mapping->private_lock); | |
841 | while (!list_empty(list)) { | |
842 | struct buffer_head *bh = BH_ENTRY(list->next); | |
843 | if (buffer_dirty(bh)) { | |
844 | ret = 0; | |
845 | break; | |
846 | } | |
847 | __remove_assoc_queue(bh); | |
848 | } | |
849 | spin_unlock(&buffer_mapping->private_lock); | |
850 | } | |
851 | return ret; | |
852 | } | |
853 | ||
854 | /* | |
855 | * Create the appropriate buffers when given a page for data area and | |
856 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
857 | * follow the buffers created. Return NULL if unable to create more | |
858 | * buffers. | |
859 | * | |
860 | * The retry flag is used to differentiate async IO (paging, swapping) | |
861 | * which may not fail from ordinary buffer allocations. | |
862 | */ | |
863 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
864 | int retry) | |
865 | { | |
866 | struct buffer_head *bh, *head; | |
867 | long offset; | |
868 | ||
869 | try_again: | |
870 | head = NULL; | |
871 | offset = PAGE_SIZE; | |
872 | while ((offset -= size) >= 0) { | |
873 | bh = alloc_buffer_head(GFP_NOFS); | |
874 | if (!bh) | |
875 | goto no_grow; | |
876 | ||
877 | bh->b_bdev = NULL; | |
878 | bh->b_this_page = head; | |
879 | bh->b_blocknr = -1; | |
880 | head = bh; | |
881 | ||
882 | bh->b_state = 0; | |
883 | atomic_set(&bh->b_count, 0); | |
fc5cd582 | 884 | bh->b_private = NULL; |
1da177e4 LT |
885 | bh->b_size = size; |
886 | ||
887 | /* Link the buffer to its page */ | |
888 | set_bh_page(bh, page, offset); | |
889 | ||
01ffe339 | 890 | init_buffer(bh, NULL, NULL); |
1da177e4 LT |
891 | } |
892 | return head; | |
893 | /* | |
894 | * In case anything failed, we just free everything we got. | |
895 | */ | |
896 | no_grow: | |
897 | if (head) { | |
898 | do { | |
899 | bh = head; | |
900 | head = head->b_this_page; | |
901 | free_buffer_head(bh); | |
902 | } while (head); | |
903 | } | |
904 | ||
905 | /* | |
906 | * Return failure for non-async IO requests. Async IO requests | |
907 | * are not allowed to fail, so we have to wait until buffer heads | |
908 | * become available. But we don't want tasks sleeping with | |
909 | * partially complete buffers, so all were released above. | |
910 | */ | |
911 | if (!retry) | |
912 | return NULL; | |
913 | ||
914 | /* We're _really_ low on memory. Now we just | |
915 | * wait for old buffer heads to become free due to | |
916 | * finishing IO. Since this is an async request and | |
917 | * the reserve list is empty, we're sure there are | |
918 | * async buffer heads in use. | |
919 | */ | |
920 | free_more_memory(); | |
921 | goto try_again; | |
922 | } | |
923 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
924 | ||
925 | static inline void | |
926 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
927 | { | |
928 | struct buffer_head *bh, *tail; | |
929 | ||
930 | bh = head; | |
931 | do { | |
932 | tail = bh; | |
933 | bh = bh->b_this_page; | |
934 | } while (bh); | |
935 | tail->b_this_page = head; | |
936 | attach_page_buffers(page, head); | |
937 | } | |
938 | ||
939 | /* | |
940 | * Initialise the state of a blockdev page's buffers. | |
941 | */ | |
942 | static void | |
943 | init_page_buffers(struct page *page, struct block_device *bdev, | |
944 | sector_t block, int size) | |
945 | { | |
946 | struct buffer_head *head = page_buffers(page); | |
947 | struct buffer_head *bh = head; | |
948 | int uptodate = PageUptodate(page); | |
949 | ||
950 | do { | |
951 | if (!buffer_mapped(bh)) { | |
952 | init_buffer(bh, NULL, NULL); | |
953 | bh->b_bdev = bdev; | |
954 | bh->b_blocknr = block; | |
955 | if (uptodate) | |
956 | set_buffer_uptodate(bh); | |
957 | set_buffer_mapped(bh); | |
958 | } | |
959 | block++; | |
960 | bh = bh->b_this_page; | |
961 | } while (bh != head); | |
962 | } | |
963 | ||
964 | /* | |
965 | * Create the page-cache page that contains the requested block. | |
966 | * | |
967 | * This is user purely for blockdev mappings. | |
968 | */ | |
969 | static struct page * | |
970 | grow_dev_page(struct block_device *bdev, sector_t block, | |
971 | pgoff_t index, int size) | |
972 | { | |
973 | struct inode *inode = bdev->bd_inode; | |
974 | struct page *page; | |
975 | struct buffer_head *bh; | |
976 | ||
ea125892 | 977 | page = find_or_create_page(inode->i_mapping, index, |
769848c0 | 978 | (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE); |
1da177e4 LT |
979 | if (!page) |
980 | return NULL; | |
981 | ||
e827f923 | 982 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
983 | |
984 | if (page_has_buffers(page)) { | |
985 | bh = page_buffers(page); | |
986 | if (bh->b_size == size) { | |
987 | init_page_buffers(page, bdev, block, size); | |
988 | return page; | |
989 | } | |
990 | if (!try_to_free_buffers(page)) | |
991 | goto failed; | |
992 | } | |
993 | ||
994 | /* | |
995 | * Allocate some buffers for this page | |
996 | */ | |
997 | bh = alloc_page_buffers(page, size, 0); | |
998 | if (!bh) | |
999 | goto failed; | |
1000 | ||
1001 | /* | |
1002 | * Link the page to the buffers and initialise them. Take the | |
1003 | * lock to be atomic wrt __find_get_block(), which does not | |
1004 | * run under the page lock. | |
1005 | */ | |
1006 | spin_lock(&inode->i_mapping->private_lock); | |
1007 | link_dev_buffers(page, bh); | |
1008 | init_page_buffers(page, bdev, block, size); | |
1009 | spin_unlock(&inode->i_mapping->private_lock); | |
1010 | return page; | |
1011 | ||
1012 | failed: | |
1013 | BUG(); | |
1014 | unlock_page(page); | |
1015 | page_cache_release(page); | |
1016 | return NULL; | |
1017 | } | |
1018 | ||
1019 | /* | |
1020 | * Create buffers for the specified block device block's page. If | |
1021 | * that page was dirty, the buffers are set dirty also. | |
1da177e4 | 1022 | */ |
858119e1 | 1023 | static int |
1da177e4 LT |
1024 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1025 | { | |
1026 | struct page *page; | |
1027 | pgoff_t index; | |
1028 | int sizebits; | |
1029 | ||
1030 | sizebits = -1; | |
1031 | do { | |
1032 | sizebits++; | |
1033 | } while ((size << sizebits) < PAGE_SIZE); | |
1034 | ||
1035 | index = block >> sizebits; | |
1da177e4 | 1036 | |
e5657933 AM |
1037 | /* |
1038 | * Check for a block which wants to lie outside our maximum possible | |
1039 | * pagecache index. (this comparison is done using sector_t types). | |
1040 | */ | |
1041 | if (unlikely(index != block >> sizebits)) { | |
1042 | char b[BDEVNAME_SIZE]; | |
1043 | ||
1044 | printk(KERN_ERR "%s: requested out-of-range block %llu for " | |
1045 | "device %s\n", | |
8e24eea7 | 1046 | __func__, (unsigned long long)block, |
e5657933 AM |
1047 | bdevname(bdev, b)); |
1048 | return -EIO; | |
1049 | } | |
1050 | block = index << sizebits; | |
1da177e4 LT |
1051 | /* Create a page with the proper size buffers.. */ |
1052 | page = grow_dev_page(bdev, block, index, size); | |
1053 | if (!page) | |
1054 | return 0; | |
1055 | unlock_page(page); | |
1056 | page_cache_release(page); | |
1057 | return 1; | |
1058 | } | |
1059 | ||
75c96f85 | 1060 | static struct buffer_head * |
1da177e4 LT |
1061 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1062 | { | |
1063 | /* Size must be multiple of hard sectorsize */ | |
1064 | if (unlikely(size & (bdev_hardsect_size(bdev)-1) || | |
1065 | (size < 512 || size > PAGE_SIZE))) { | |
1066 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1067 | size); | |
1068 | printk(KERN_ERR "hardsect size: %d\n", | |
1069 | bdev_hardsect_size(bdev)); | |
1070 | ||
1071 | dump_stack(); | |
1072 | return NULL; | |
1073 | } | |
1074 | ||
1075 | for (;;) { | |
1076 | struct buffer_head * bh; | |
e5657933 | 1077 | int ret; |
1da177e4 LT |
1078 | |
1079 | bh = __find_get_block(bdev, block, size); | |
1080 | if (bh) | |
1081 | return bh; | |
1082 | ||
e5657933 AM |
1083 | ret = grow_buffers(bdev, block, size); |
1084 | if (ret < 0) | |
1085 | return NULL; | |
1086 | if (ret == 0) | |
1da177e4 LT |
1087 | free_more_memory(); |
1088 | } | |
1089 | } | |
1090 | ||
1091 | /* | |
1092 | * The relationship between dirty buffers and dirty pages: | |
1093 | * | |
1094 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1095 | * the page is tagged dirty in its radix tree. | |
1096 | * | |
1097 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1098 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1099 | * merely a hint about the true dirty state. | |
1100 | * | |
1101 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1102 | * (if the page has buffers). | |
1103 | * | |
1104 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1105 | * buffers are not. | |
1106 | * | |
1107 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1108 | * individually become uptodate. But their backing page remains not | |
1109 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1110 | * block_read_full_page() against that page will discover all the uptodate | |
1111 | * buffers, will set the page uptodate and will perform no I/O. | |
1112 | */ | |
1113 | ||
1114 | /** | |
1115 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1116 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1117 | * |
1118 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1119 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1120 | * tree and then attach the address_space's inode to its superblock's dirty | |
1121 | * inode list. | |
1122 | * | |
1123 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
1124 | * mapping->tree_lock and the global inode_lock. | |
1125 | */ | |
fc9b52cd | 1126 | void mark_buffer_dirty(struct buffer_head *bh) |
1da177e4 | 1127 | { |
787d2214 | 1128 | WARN_ON_ONCE(!buffer_uptodate(bh)); |
1be62dc1 LT |
1129 | |
1130 | /* | |
1131 | * Very *carefully* optimize the it-is-already-dirty case. | |
1132 | * | |
1133 | * Don't let the final "is it dirty" escape to before we | |
1134 | * perhaps modified the buffer. | |
1135 | */ | |
1136 | if (buffer_dirty(bh)) { | |
1137 | smp_mb(); | |
1138 | if (buffer_dirty(bh)) | |
1139 | return; | |
1140 | } | |
1141 | ||
a8e7d49a LT |
1142 | if (!test_set_buffer_dirty(bh)) { |
1143 | struct page *page = bh->b_page; | |
1144 | if (!TestSetPageDirty(page)) | |
1145 | __set_page_dirty(page, page_mapping(page), 0); | |
1146 | } | |
1da177e4 LT |
1147 | } |
1148 | ||
1149 | /* | |
1150 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1151 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1152 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1153 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1154 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1155 | */ | |
1156 | void __brelse(struct buffer_head * buf) | |
1157 | { | |
1158 | if (atomic_read(&buf->b_count)) { | |
1159 | put_bh(buf); | |
1160 | return; | |
1161 | } | |
5c752ad9 | 1162 | WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n"); |
1da177e4 LT |
1163 | } |
1164 | ||
1165 | /* | |
1166 | * bforget() is like brelse(), except it discards any | |
1167 | * potentially dirty data. | |
1168 | */ | |
1169 | void __bforget(struct buffer_head *bh) | |
1170 | { | |
1171 | clear_buffer_dirty(bh); | |
535ee2fb | 1172 | if (bh->b_assoc_map) { |
1da177e4 LT |
1173 | struct address_space *buffer_mapping = bh->b_page->mapping; |
1174 | ||
1175 | spin_lock(&buffer_mapping->private_lock); | |
1176 | list_del_init(&bh->b_assoc_buffers); | |
58ff407b | 1177 | bh->b_assoc_map = NULL; |
1da177e4 LT |
1178 | spin_unlock(&buffer_mapping->private_lock); |
1179 | } | |
1180 | __brelse(bh); | |
1181 | } | |
1182 | ||
1183 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1184 | { | |
1185 | lock_buffer(bh); | |
1186 | if (buffer_uptodate(bh)) { | |
1187 | unlock_buffer(bh); | |
1188 | return bh; | |
1189 | } else { | |
1190 | get_bh(bh); | |
1191 | bh->b_end_io = end_buffer_read_sync; | |
1192 | submit_bh(READ, bh); | |
1193 | wait_on_buffer(bh); | |
1194 | if (buffer_uptodate(bh)) | |
1195 | return bh; | |
1196 | } | |
1197 | brelse(bh); | |
1198 | return NULL; | |
1199 | } | |
1200 | ||
1201 | /* | |
1202 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1203 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1204 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1205 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1206 | * CPU's LRUs at the same time. | |
1207 | * | |
1208 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1209 | * sb_find_get_block(). | |
1210 | * | |
1211 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1212 | * a local interrupt disable for that. | |
1213 | */ | |
1214 | ||
1215 | #define BH_LRU_SIZE 8 | |
1216 | ||
1217 | struct bh_lru { | |
1218 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1219 | }; | |
1220 | ||
1221 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1222 | ||
1223 | #ifdef CONFIG_SMP | |
1224 | #define bh_lru_lock() local_irq_disable() | |
1225 | #define bh_lru_unlock() local_irq_enable() | |
1226 | #else | |
1227 | #define bh_lru_lock() preempt_disable() | |
1228 | #define bh_lru_unlock() preempt_enable() | |
1229 | #endif | |
1230 | ||
1231 | static inline void check_irqs_on(void) | |
1232 | { | |
1233 | #ifdef irqs_disabled | |
1234 | BUG_ON(irqs_disabled()); | |
1235 | #endif | |
1236 | } | |
1237 | ||
1238 | /* | |
1239 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1240 | */ | |
1241 | static void bh_lru_install(struct buffer_head *bh) | |
1242 | { | |
1243 | struct buffer_head *evictee = NULL; | |
1244 | struct bh_lru *lru; | |
1245 | ||
1246 | check_irqs_on(); | |
1247 | bh_lru_lock(); | |
1248 | lru = &__get_cpu_var(bh_lrus); | |
1249 | if (lru->bhs[0] != bh) { | |
1250 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1251 | int in; | |
1252 | int out = 0; | |
1253 | ||
1254 | get_bh(bh); | |
1255 | bhs[out++] = bh; | |
1256 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
1257 | struct buffer_head *bh2 = lru->bhs[in]; | |
1258 | ||
1259 | if (bh2 == bh) { | |
1260 | __brelse(bh2); | |
1261 | } else { | |
1262 | if (out >= BH_LRU_SIZE) { | |
1263 | BUG_ON(evictee != NULL); | |
1264 | evictee = bh2; | |
1265 | } else { | |
1266 | bhs[out++] = bh2; | |
1267 | } | |
1268 | } | |
1269 | } | |
1270 | while (out < BH_LRU_SIZE) | |
1271 | bhs[out++] = NULL; | |
1272 | memcpy(lru->bhs, bhs, sizeof(bhs)); | |
1273 | } | |
1274 | bh_lru_unlock(); | |
1275 | ||
1276 | if (evictee) | |
1277 | __brelse(evictee); | |
1278 | } | |
1279 | ||
1280 | /* | |
1281 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1282 | */ | |
858119e1 | 1283 | static struct buffer_head * |
3991d3bd | 1284 | lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1285 | { |
1286 | struct buffer_head *ret = NULL; | |
1287 | struct bh_lru *lru; | |
3991d3bd | 1288 | unsigned int i; |
1da177e4 LT |
1289 | |
1290 | check_irqs_on(); | |
1291 | bh_lru_lock(); | |
1292 | lru = &__get_cpu_var(bh_lrus); | |
1293 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1294 | struct buffer_head *bh = lru->bhs[i]; | |
1295 | ||
1296 | if (bh && bh->b_bdev == bdev && | |
1297 | bh->b_blocknr == block && bh->b_size == size) { | |
1298 | if (i) { | |
1299 | while (i) { | |
1300 | lru->bhs[i] = lru->bhs[i - 1]; | |
1301 | i--; | |
1302 | } | |
1303 | lru->bhs[0] = bh; | |
1304 | } | |
1305 | get_bh(bh); | |
1306 | ret = bh; | |
1307 | break; | |
1308 | } | |
1309 | } | |
1310 | bh_lru_unlock(); | |
1311 | return ret; | |
1312 | } | |
1313 | ||
1314 | /* | |
1315 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1316 | * it in the LRU and mark it as accessed. If it is not present then return | |
1317 | * NULL | |
1318 | */ | |
1319 | struct buffer_head * | |
3991d3bd | 1320 | __find_get_block(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1321 | { |
1322 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1323 | ||
1324 | if (bh == NULL) { | |
385fd4c5 | 1325 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1326 | if (bh) |
1327 | bh_lru_install(bh); | |
1328 | } | |
1329 | if (bh) | |
1330 | touch_buffer(bh); | |
1331 | return bh; | |
1332 | } | |
1333 | EXPORT_SYMBOL(__find_get_block); | |
1334 | ||
1335 | /* | |
1336 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1337 | * which corresponds to the passed block_device, block and size. The | |
1338 | * returned buffer has its reference count incremented. | |
1339 | * | |
1340 | * __getblk() cannot fail - it just keeps trying. If you pass it an | |
1341 | * illegal block number, __getblk() will happily return a buffer_head | |
1342 | * which represents the non-existent block. Very weird. | |
1343 | * | |
1344 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() | |
1345 | * attempt is failing. FIXME, perhaps? | |
1346 | */ | |
1347 | struct buffer_head * | |
3991d3bd | 1348 | __getblk(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1349 | { |
1350 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1351 | ||
1352 | might_sleep(); | |
1353 | if (bh == NULL) | |
1354 | bh = __getblk_slow(bdev, block, size); | |
1355 | return bh; | |
1356 | } | |
1357 | EXPORT_SYMBOL(__getblk); | |
1358 | ||
1359 | /* | |
1360 | * Do async read-ahead on a buffer.. | |
1361 | */ | |
3991d3bd | 1362 | void __breadahead(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1363 | { |
1364 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1365 | if (likely(bh)) { |
1366 | ll_rw_block(READA, 1, &bh); | |
1367 | brelse(bh); | |
1368 | } | |
1da177e4 LT |
1369 | } |
1370 | EXPORT_SYMBOL(__breadahead); | |
1371 | ||
1372 | /** | |
1373 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1374 | * @bdev: the block_device to read from |
1da177e4 LT |
1375 | * @block: number of block |
1376 | * @size: size (in bytes) to read | |
1377 | * | |
1378 | * Reads a specified block, and returns buffer head that contains it. | |
1379 | * It returns NULL if the block was unreadable. | |
1380 | */ | |
1381 | struct buffer_head * | |
3991d3bd | 1382 | __bread(struct block_device *bdev, sector_t block, unsigned size) |
1da177e4 LT |
1383 | { |
1384 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1385 | ||
a3e713b5 | 1386 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1387 | bh = __bread_slow(bh); |
1388 | return bh; | |
1389 | } | |
1390 | EXPORT_SYMBOL(__bread); | |
1391 | ||
1392 | /* | |
1393 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1394 | * This doesn't race because it runs in each cpu either in irq | |
1395 | * or with preempt disabled. | |
1396 | */ | |
1397 | static void invalidate_bh_lru(void *arg) | |
1398 | { | |
1399 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1400 | int i; | |
1401 | ||
1402 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1403 | brelse(b->bhs[i]); | |
1404 | b->bhs[i] = NULL; | |
1405 | } | |
1406 | put_cpu_var(bh_lrus); | |
1407 | } | |
1408 | ||
f9a14399 | 1409 | void invalidate_bh_lrus(void) |
1da177e4 | 1410 | { |
15c8b6c1 | 1411 | on_each_cpu(invalidate_bh_lru, NULL, 1); |
1da177e4 | 1412 | } |
9db5579b | 1413 | EXPORT_SYMBOL_GPL(invalidate_bh_lrus); |
1da177e4 LT |
1414 | |
1415 | void set_bh_page(struct buffer_head *bh, | |
1416 | struct page *page, unsigned long offset) | |
1417 | { | |
1418 | bh->b_page = page; | |
e827f923 | 1419 | BUG_ON(offset >= PAGE_SIZE); |
1da177e4 LT |
1420 | if (PageHighMem(page)) |
1421 | /* | |
1422 | * This catches illegal uses and preserves the offset: | |
1423 | */ | |
1424 | bh->b_data = (char *)(0 + offset); | |
1425 | else | |
1426 | bh->b_data = page_address(page) + offset; | |
1427 | } | |
1428 | EXPORT_SYMBOL(set_bh_page); | |
1429 | ||
1430 | /* | |
1431 | * Called when truncating a buffer on a page completely. | |
1432 | */ | |
858119e1 | 1433 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1434 | { |
1435 | lock_buffer(bh); | |
1436 | clear_buffer_dirty(bh); | |
1437 | bh->b_bdev = NULL; | |
1438 | clear_buffer_mapped(bh); | |
1439 | clear_buffer_req(bh); | |
1440 | clear_buffer_new(bh); | |
1441 | clear_buffer_delay(bh); | |
33a266dd | 1442 | clear_buffer_unwritten(bh); |
1da177e4 LT |
1443 | unlock_buffer(bh); |
1444 | } | |
1445 | ||
1da177e4 LT |
1446 | /** |
1447 | * block_invalidatepage - invalidate part of all of a buffer-backed page | |
1448 | * | |
1449 | * @page: the page which is affected | |
1450 | * @offset: the index of the truncation point | |
1451 | * | |
1452 | * block_invalidatepage() is called when all or part of the page has become | |
1453 | * invalidatedby a truncate operation. | |
1454 | * | |
1455 | * block_invalidatepage() does not have to release all buffers, but it must | |
1456 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1457 | * is underway against any of the blocks which are outside the truncation | |
1458 | * point. Because the caller is about to free (and possibly reuse) those | |
1459 | * blocks on-disk. | |
1460 | */ | |
2ff28e22 | 1461 | void block_invalidatepage(struct page *page, unsigned long offset) |
1da177e4 LT |
1462 | { |
1463 | struct buffer_head *head, *bh, *next; | |
1464 | unsigned int curr_off = 0; | |
1da177e4 LT |
1465 | |
1466 | BUG_ON(!PageLocked(page)); | |
1467 | if (!page_has_buffers(page)) | |
1468 | goto out; | |
1469 | ||
1470 | head = page_buffers(page); | |
1471 | bh = head; | |
1472 | do { | |
1473 | unsigned int next_off = curr_off + bh->b_size; | |
1474 | next = bh->b_this_page; | |
1475 | ||
1476 | /* | |
1477 | * is this block fully invalidated? | |
1478 | */ | |
1479 | if (offset <= curr_off) | |
1480 | discard_buffer(bh); | |
1481 | curr_off = next_off; | |
1482 | bh = next; | |
1483 | } while (bh != head); | |
1484 | ||
1485 | /* | |
1486 | * We release buffers only if the entire page is being invalidated. | |
1487 | * The get_block cached value has been unconditionally invalidated, | |
1488 | * so real IO is not possible anymore. | |
1489 | */ | |
1490 | if (offset == 0) | |
2ff28e22 | 1491 | try_to_release_page(page, 0); |
1da177e4 | 1492 | out: |
2ff28e22 | 1493 | return; |
1da177e4 LT |
1494 | } |
1495 | EXPORT_SYMBOL(block_invalidatepage); | |
1496 | ||
1497 | /* | |
1498 | * We attach and possibly dirty the buffers atomically wrt | |
1499 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1500 | * is already excluded via the page lock. | |
1501 | */ | |
1502 | void create_empty_buffers(struct page *page, | |
1503 | unsigned long blocksize, unsigned long b_state) | |
1504 | { | |
1505 | struct buffer_head *bh, *head, *tail; | |
1506 | ||
1507 | head = alloc_page_buffers(page, blocksize, 1); | |
1508 | bh = head; | |
1509 | do { | |
1510 | bh->b_state |= b_state; | |
1511 | tail = bh; | |
1512 | bh = bh->b_this_page; | |
1513 | } while (bh); | |
1514 | tail->b_this_page = head; | |
1515 | ||
1516 | spin_lock(&page->mapping->private_lock); | |
1517 | if (PageUptodate(page) || PageDirty(page)) { | |
1518 | bh = head; | |
1519 | do { | |
1520 | if (PageDirty(page)) | |
1521 | set_buffer_dirty(bh); | |
1522 | if (PageUptodate(page)) | |
1523 | set_buffer_uptodate(bh); | |
1524 | bh = bh->b_this_page; | |
1525 | } while (bh != head); | |
1526 | } | |
1527 | attach_page_buffers(page, head); | |
1528 | spin_unlock(&page->mapping->private_lock); | |
1529 | } | |
1530 | EXPORT_SYMBOL(create_empty_buffers); | |
1531 | ||
1532 | /* | |
1533 | * We are taking a block for data and we don't want any output from any | |
1534 | * buffer-cache aliases starting from return from that function and | |
1535 | * until the moment when something will explicitly mark the buffer | |
1536 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1537 | * We don't even need to mark it not-uptodate - nobody can expect | |
1538 | * anything from a newly allocated buffer anyway. We used to used | |
1539 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1540 | * don't want to mark the alias unmapped, for example - it would confuse | |
1541 | * anyone who might pick it with bread() afterwards... | |
1542 | * | |
1543 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1544 | * be writeout I/O going on against recently-freed buffers. We don't | |
1545 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1546 | * only if we really need to. That happens here. | |
1547 | */ | |
1548 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1549 | { | |
1550 | struct buffer_head *old_bh; | |
1551 | ||
1552 | might_sleep(); | |
1553 | ||
385fd4c5 | 1554 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1555 | if (old_bh) { |
1556 | clear_buffer_dirty(old_bh); | |
1557 | wait_on_buffer(old_bh); | |
1558 | clear_buffer_req(old_bh); | |
1559 | __brelse(old_bh); | |
1560 | } | |
1561 | } | |
1562 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1563 | ||
1564 | /* | |
1565 | * NOTE! All mapped/uptodate combinations are valid: | |
1566 | * | |
1567 | * Mapped Uptodate Meaning | |
1568 | * | |
1569 | * No No "unknown" - must do get_block() | |
1570 | * No Yes "hole" - zero-filled | |
1571 | * Yes No "allocated" - allocated on disk, not read in | |
1572 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1573 | * | |
1574 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1575 | */ | |
1576 | ||
1577 | /* | |
1578 | * While block_write_full_page is writing back the dirty buffers under | |
1579 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1580 | * again at any time. We handle that by only looking at the buffer | |
1581 | * state inside lock_buffer(). | |
1582 | * | |
1583 | * If block_write_full_page() is called for regular writeback | |
1584 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1585 | * locked buffer. This only can happen if someone has written the buffer | |
1586 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1587 | * prevents this contention from occurring. | |
1588 | */ | |
1589 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
1590 | get_block_t *get_block, struct writeback_control *wbc) | |
1591 | { | |
1592 | int err; | |
1593 | sector_t block; | |
1594 | sector_t last_block; | |
f0fbd5fc | 1595 | struct buffer_head *bh, *head; |
b0cf2321 | 1596 | const unsigned blocksize = 1 << inode->i_blkbits; |
1da177e4 | 1597 | int nr_underway = 0; |
a64c8610 | 1598 | int write_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); |
1da177e4 LT |
1599 | |
1600 | BUG_ON(!PageLocked(page)); | |
1601 | ||
1602 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; | |
1603 | ||
1604 | if (!page_has_buffers(page)) { | |
b0cf2321 | 1605 | create_empty_buffers(page, blocksize, |
1da177e4 LT |
1606 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1607 | } | |
1608 | ||
1609 | /* | |
1610 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1611 | * here, and the (potentially unmapped) buffers may become dirty at | |
1612 | * any time. If a buffer becomes dirty here after we've inspected it | |
1613 | * then we just miss that fact, and the page stays dirty. | |
1614 | * | |
1615 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1616 | * handle that here by just cleaning them. | |
1617 | */ | |
1618 | ||
54b21a79 | 1619 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
1620 | head = page_buffers(page); |
1621 | bh = head; | |
1622 | ||
1623 | /* | |
1624 | * Get all the dirty buffers mapped to disk addresses and | |
1625 | * handle any aliases from the underlying blockdev's mapping. | |
1626 | */ | |
1627 | do { | |
1628 | if (block > last_block) { | |
1629 | /* | |
1630 | * mapped buffers outside i_size will occur, because | |
1631 | * this page can be outside i_size when there is a | |
1632 | * truncate in progress. | |
1633 | */ | |
1634 | /* | |
1635 | * The buffer was zeroed by block_write_full_page() | |
1636 | */ | |
1637 | clear_buffer_dirty(bh); | |
1638 | set_buffer_uptodate(bh); | |
29a814d2 AT |
1639 | } else if ((!buffer_mapped(bh) || buffer_delay(bh)) && |
1640 | buffer_dirty(bh)) { | |
b0cf2321 | 1641 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1642 | err = get_block(inode, block, bh, 1); |
1643 | if (err) | |
1644 | goto recover; | |
29a814d2 | 1645 | clear_buffer_delay(bh); |
1da177e4 LT |
1646 | if (buffer_new(bh)) { |
1647 | /* blockdev mappings never come here */ | |
1648 | clear_buffer_new(bh); | |
1649 | unmap_underlying_metadata(bh->b_bdev, | |
1650 | bh->b_blocknr); | |
1651 | } | |
1652 | } | |
1653 | bh = bh->b_this_page; | |
1654 | block++; | |
1655 | } while (bh != head); | |
1656 | ||
1657 | do { | |
1da177e4 LT |
1658 | if (!buffer_mapped(bh)) |
1659 | continue; | |
1660 | /* | |
1661 | * If it's a fully non-blocking write attempt and we cannot | |
1662 | * lock the buffer then redirty the page. Note that this can | |
1663 | * potentially cause a busy-wait loop from pdflush and kswapd | |
1664 | * activity, but those code paths have their own higher-level | |
1665 | * throttling. | |
1666 | */ | |
1667 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { | |
1668 | lock_buffer(bh); | |
ca5de404 | 1669 | } else if (!trylock_buffer(bh)) { |
1da177e4 LT |
1670 | redirty_page_for_writepage(wbc, page); |
1671 | continue; | |
1672 | } | |
1673 | if (test_clear_buffer_dirty(bh)) { | |
1674 | mark_buffer_async_write(bh); | |
1675 | } else { | |
1676 | unlock_buffer(bh); | |
1677 | } | |
1678 | } while ((bh = bh->b_this_page) != head); | |
1679 | ||
1680 | /* | |
1681 | * The page and its buffers are protected by PageWriteback(), so we can | |
1682 | * drop the bh refcounts early. | |
1683 | */ | |
1684 | BUG_ON(PageWriteback(page)); | |
1685 | set_page_writeback(page); | |
1da177e4 LT |
1686 | |
1687 | do { | |
1688 | struct buffer_head *next = bh->b_this_page; | |
1689 | if (buffer_async_write(bh)) { | |
a64c8610 | 1690 | submit_bh(write_op, bh); |
1da177e4 LT |
1691 | nr_underway++; |
1692 | } | |
1da177e4 LT |
1693 | bh = next; |
1694 | } while (bh != head); | |
05937baa | 1695 | unlock_page(page); |
1da177e4 LT |
1696 | |
1697 | err = 0; | |
1698 | done: | |
1699 | if (nr_underway == 0) { | |
1700 | /* | |
1701 | * The page was marked dirty, but the buffers were | |
1702 | * clean. Someone wrote them back by hand with | |
1703 | * ll_rw_block/submit_bh. A rare case. | |
1704 | */ | |
1da177e4 | 1705 | end_page_writeback(page); |
3d67f2d7 | 1706 | |
1da177e4 LT |
1707 | /* |
1708 | * The page and buffer_heads can be released at any time from | |
1709 | * here on. | |
1710 | */ | |
1da177e4 LT |
1711 | } |
1712 | return err; | |
1713 | ||
1714 | recover: | |
1715 | /* | |
1716 | * ENOSPC, or some other error. We may already have added some | |
1717 | * blocks to the file, so we need to write these out to avoid | |
1718 | * exposing stale data. | |
1719 | * The page is currently locked and not marked for writeback | |
1720 | */ | |
1721 | bh = head; | |
1722 | /* Recovery: lock and submit the mapped buffers */ | |
1723 | do { | |
29a814d2 AT |
1724 | if (buffer_mapped(bh) && buffer_dirty(bh) && |
1725 | !buffer_delay(bh)) { | |
1da177e4 LT |
1726 | lock_buffer(bh); |
1727 | mark_buffer_async_write(bh); | |
1728 | } else { | |
1729 | /* | |
1730 | * The buffer may have been set dirty during | |
1731 | * attachment to a dirty page. | |
1732 | */ | |
1733 | clear_buffer_dirty(bh); | |
1734 | } | |
1735 | } while ((bh = bh->b_this_page) != head); | |
1736 | SetPageError(page); | |
1737 | BUG_ON(PageWriteback(page)); | |
7e4c3690 | 1738 | mapping_set_error(page->mapping, err); |
1da177e4 | 1739 | set_page_writeback(page); |
1da177e4 LT |
1740 | do { |
1741 | struct buffer_head *next = bh->b_this_page; | |
1742 | if (buffer_async_write(bh)) { | |
1743 | clear_buffer_dirty(bh); | |
a64c8610 | 1744 | submit_bh(write_op, bh); |
1da177e4 LT |
1745 | nr_underway++; |
1746 | } | |
1da177e4 LT |
1747 | bh = next; |
1748 | } while (bh != head); | |
ffda9d30 | 1749 | unlock_page(page); |
1da177e4 LT |
1750 | goto done; |
1751 | } | |
1752 | ||
afddba49 NP |
1753 | /* |
1754 | * If a page has any new buffers, zero them out here, and mark them uptodate | |
1755 | * and dirty so they'll be written out (in order to prevent uninitialised | |
1756 | * block data from leaking). And clear the new bit. | |
1757 | */ | |
1758 | void page_zero_new_buffers(struct page *page, unsigned from, unsigned to) | |
1759 | { | |
1760 | unsigned int block_start, block_end; | |
1761 | struct buffer_head *head, *bh; | |
1762 | ||
1763 | BUG_ON(!PageLocked(page)); | |
1764 | if (!page_has_buffers(page)) | |
1765 | return; | |
1766 | ||
1767 | bh = head = page_buffers(page); | |
1768 | block_start = 0; | |
1769 | do { | |
1770 | block_end = block_start + bh->b_size; | |
1771 | ||
1772 | if (buffer_new(bh)) { | |
1773 | if (block_end > from && block_start < to) { | |
1774 | if (!PageUptodate(page)) { | |
1775 | unsigned start, size; | |
1776 | ||
1777 | start = max(from, block_start); | |
1778 | size = min(to, block_end) - start; | |
1779 | ||
eebd2aa3 | 1780 | zero_user(page, start, size); |
afddba49 NP |
1781 | set_buffer_uptodate(bh); |
1782 | } | |
1783 | ||
1784 | clear_buffer_new(bh); | |
1785 | mark_buffer_dirty(bh); | |
1786 | } | |
1787 | } | |
1788 | ||
1789 | block_start = block_end; | |
1790 | bh = bh->b_this_page; | |
1791 | } while (bh != head); | |
1792 | } | |
1793 | EXPORT_SYMBOL(page_zero_new_buffers); | |
1794 | ||
1da177e4 LT |
1795 | static int __block_prepare_write(struct inode *inode, struct page *page, |
1796 | unsigned from, unsigned to, get_block_t *get_block) | |
1797 | { | |
1798 | unsigned block_start, block_end; | |
1799 | sector_t block; | |
1800 | int err = 0; | |
1801 | unsigned blocksize, bbits; | |
1802 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1803 | ||
1804 | BUG_ON(!PageLocked(page)); | |
1805 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1806 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1807 | BUG_ON(from > to); | |
1808 | ||
1809 | blocksize = 1 << inode->i_blkbits; | |
1810 | if (!page_has_buffers(page)) | |
1811 | create_empty_buffers(page, blocksize, 0); | |
1812 | head = page_buffers(page); | |
1813 | ||
1814 | bbits = inode->i_blkbits; | |
1815 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1816 | ||
1817 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1818 | block++, block_start=block_end, bh = bh->b_this_page) { | |
1819 | block_end = block_start + blocksize; | |
1820 | if (block_end <= from || block_start >= to) { | |
1821 | if (PageUptodate(page)) { | |
1822 | if (!buffer_uptodate(bh)) | |
1823 | set_buffer_uptodate(bh); | |
1824 | } | |
1825 | continue; | |
1826 | } | |
1827 | if (buffer_new(bh)) | |
1828 | clear_buffer_new(bh); | |
1829 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1830 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1831 | err = get_block(inode, block, bh, 1); |
1832 | if (err) | |
f3ddbdc6 | 1833 | break; |
1da177e4 | 1834 | if (buffer_new(bh)) { |
1da177e4 LT |
1835 | unmap_underlying_metadata(bh->b_bdev, |
1836 | bh->b_blocknr); | |
1837 | if (PageUptodate(page)) { | |
637aff46 | 1838 | clear_buffer_new(bh); |
1da177e4 | 1839 | set_buffer_uptodate(bh); |
637aff46 | 1840 | mark_buffer_dirty(bh); |
1da177e4 LT |
1841 | continue; |
1842 | } | |
eebd2aa3 CL |
1843 | if (block_end > to || block_start < from) |
1844 | zero_user_segments(page, | |
1845 | to, block_end, | |
1846 | block_start, from); | |
1da177e4 LT |
1847 | continue; |
1848 | } | |
1849 | } | |
1850 | if (PageUptodate(page)) { | |
1851 | if (!buffer_uptodate(bh)) | |
1852 | set_buffer_uptodate(bh); | |
1853 | continue; | |
1854 | } | |
1855 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
33a266dd | 1856 | !buffer_unwritten(bh) && |
1da177e4 LT |
1857 | (block_start < from || block_end > to)) { |
1858 | ll_rw_block(READ, 1, &bh); | |
1859 | *wait_bh++=bh; | |
1860 | } | |
1861 | } | |
1862 | /* | |
1863 | * If we issued read requests - let them complete. | |
1864 | */ | |
1865 | while(wait_bh > wait) { | |
1866 | wait_on_buffer(*--wait_bh); | |
1867 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1868 | err = -EIO; |
1da177e4 | 1869 | } |
afddba49 NP |
1870 | if (unlikely(err)) |
1871 | page_zero_new_buffers(page, from, to); | |
1da177e4 LT |
1872 | return err; |
1873 | } | |
1874 | ||
1875 | static int __block_commit_write(struct inode *inode, struct page *page, | |
1876 | unsigned from, unsigned to) | |
1877 | { | |
1878 | unsigned block_start, block_end; | |
1879 | int partial = 0; | |
1880 | unsigned blocksize; | |
1881 | struct buffer_head *bh, *head; | |
1882 | ||
1883 | blocksize = 1 << inode->i_blkbits; | |
1884 | ||
1885 | for(bh = head = page_buffers(page), block_start = 0; | |
1886 | bh != head || !block_start; | |
1887 | block_start=block_end, bh = bh->b_this_page) { | |
1888 | block_end = block_start + blocksize; | |
1889 | if (block_end <= from || block_start >= to) { | |
1890 | if (!buffer_uptodate(bh)) | |
1891 | partial = 1; | |
1892 | } else { | |
1893 | set_buffer_uptodate(bh); | |
1894 | mark_buffer_dirty(bh); | |
1895 | } | |
afddba49 | 1896 | clear_buffer_new(bh); |
1da177e4 LT |
1897 | } |
1898 | ||
1899 | /* | |
1900 | * If this is a partial write which happened to make all buffers | |
1901 | * uptodate then we can optimize away a bogus readpage() for | |
1902 | * the next read(). Here we 'discover' whether the page went | |
1903 | * uptodate as a result of this (potentially partial) write. | |
1904 | */ | |
1905 | if (!partial) | |
1906 | SetPageUptodate(page); | |
1907 | return 0; | |
1908 | } | |
1909 | ||
afddba49 NP |
1910 | /* |
1911 | * block_write_begin takes care of the basic task of block allocation and | |
1912 | * bringing partial write blocks uptodate first. | |
1913 | * | |
1914 | * If *pagep is not NULL, then block_write_begin uses the locked page | |
1915 | * at *pagep rather than allocating its own. In this case, the page will | |
1916 | * not be unlocked or deallocated on failure. | |
1917 | */ | |
1918 | int block_write_begin(struct file *file, struct address_space *mapping, | |
1919 | loff_t pos, unsigned len, unsigned flags, | |
1920 | struct page **pagep, void **fsdata, | |
1921 | get_block_t *get_block) | |
1922 | { | |
1923 | struct inode *inode = mapping->host; | |
1924 | int status = 0; | |
1925 | struct page *page; | |
1926 | pgoff_t index; | |
1927 | unsigned start, end; | |
1928 | int ownpage = 0; | |
1929 | ||
1930 | index = pos >> PAGE_CACHE_SHIFT; | |
1931 | start = pos & (PAGE_CACHE_SIZE - 1); | |
1932 | end = start + len; | |
1933 | ||
1934 | page = *pagep; | |
1935 | if (page == NULL) { | |
1936 | ownpage = 1; | |
54566b2c | 1937 | page = grab_cache_page_write_begin(mapping, index, flags); |
afddba49 NP |
1938 | if (!page) { |
1939 | status = -ENOMEM; | |
1940 | goto out; | |
1941 | } | |
1942 | *pagep = page; | |
1943 | } else | |
1944 | BUG_ON(!PageLocked(page)); | |
1945 | ||
1946 | status = __block_prepare_write(inode, page, start, end, get_block); | |
1947 | if (unlikely(status)) { | |
1948 | ClearPageUptodate(page); | |
1949 | ||
1950 | if (ownpage) { | |
1951 | unlock_page(page); | |
1952 | page_cache_release(page); | |
1953 | *pagep = NULL; | |
1954 | ||
1955 | /* | |
1956 | * prepare_write() may have instantiated a few blocks | |
1957 | * outside i_size. Trim these off again. Don't need | |
1958 | * i_size_read because we hold i_mutex. | |
1959 | */ | |
1960 | if (pos + len > inode->i_size) | |
1961 | vmtruncate(inode, inode->i_size); | |
1962 | } | |
afddba49 NP |
1963 | } |
1964 | ||
1965 | out: | |
1966 | return status; | |
1967 | } | |
1968 | EXPORT_SYMBOL(block_write_begin); | |
1969 | ||
1970 | int block_write_end(struct file *file, struct address_space *mapping, | |
1971 | loff_t pos, unsigned len, unsigned copied, | |
1972 | struct page *page, void *fsdata) | |
1973 | { | |
1974 | struct inode *inode = mapping->host; | |
1975 | unsigned start; | |
1976 | ||
1977 | start = pos & (PAGE_CACHE_SIZE - 1); | |
1978 | ||
1979 | if (unlikely(copied < len)) { | |
1980 | /* | |
1981 | * The buffers that were written will now be uptodate, so we | |
1982 | * don't have to worry about a readpage reading them and | |
1983 | * overwriting a partial write. However if we have encountered | |
1984 | * a short write and only partially written into a buffer, it | |
1985 | * will not be marked uptodate, so a readpage might come in and | |
1986 | * destroy our partial write. | |
1987 | * | |
1988 | * Do the simplest thing, and just treat any short write to a | |
1989 | * non uptodate page as a zero-length write, and force the | |
1990 | * caller to redo the whole thing. | |
1991 | */ | |
1992 | if (!PageUptodate(page)) | |
1993 | copied = 0; | |
1994 | ||
1995 | page_zero_new_buffers(page, start+copied, start+len); | |
1996 | } | |
1997 | flush_dcache_page(page); | |
1998 | ||
1999 | /* This could be a short (even 0-length) commit */ | |
2000 | __block_commit_write(inode, page, start, start+copied); | |
2001 | ||
2002 | return copied; | |
2003 | } | |
2004 | EXPORT_SYMBOL(block_write_end); | |
2005 | ||
2006 | int generic_write_end(struct file *file, struct address_space *mapping, | |
2007 | loff_t pos, unsigned len, unsigned copied, | |
2008 | struct page *page, void *fsdata) | |
2009 | { | |
2010 | struct inode *inode = mapping->host; | |
c7d206b3 | 2011 | int i_size_changed = 0; |
afddba49 NP |
2012 | |
2013 | copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
2014 | ||
2015 | /* | |
2016 | * No need to use i_size_read() here, the i_size | |
2017 | * cannot change under us because we hold i_mutex. | |
2018 | * | |
2019 | * But it's important to update i_size while still holding page lock: | |
2020 | * page writeout could otherwise come in and zero beyond i_size. | |
2021 | */ | |
2022 | if (pos+copied > inode->i_size) { | |
2023 | i_size_write(inode, pos+copied); | |
c7d206b3 | 2024 | i_size_changed = 1; |
afddba49 NP |
2025 | } |
2026 | ||
2027 | unlock_page(page); | |
2028 | page_cache_release(page); | |
2029 | ||
c7d206b3 JK |
2030 | /* |
2031 | * Don't mark the inode dirty under page lock. First, it unnecessarily | |
2032 | * makes the holding time of page lock longer. Second, it forces lock | |
2033 | * ordering of page lock and transaction start for journaling | |
2034 | * filesystems. | |
2035 | */ | |
2036 | if (i_size_changed) | |
2037 | mark_inode_dirty(inode); | |
2038 | ||
afddba49 NP |
2039 | return copied; |
2040 | } | |
2041 | EXPORT_SYMBOL(generic_write_end); | |
2042 | ||
8ab22b9a HH |
2043 | /* |
2044 | * block_is_partially_uptodate checks whether buffers within a page are | |
2045 | * uptodate or not. | |
2046 | * | |
2047 | * Returns true if all buffers which correspond to a file portion | |
2048 | * we want to read are uptodate. | |
2049 | */ | |
2050 | int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc, | |
2051 | unsigned long from) | |
2052 | { | |
2053 | struct inode *inode = page->mapping->host; | |
2054 | unsigned block_start, block_end, blocksize; | |
2055 | unsigned to; | |
2056 | struct buffer_head *bh, *head; | |
2057 | int ret = 1; | |
2058 | ||
2059 | if (!page_has_buffers(page)) | |
2060 | return 0; | |
2061 | ||
2062 | blocksize = 1 << inode->i_blkbits; | |
2063 | to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count); | |
2064 | to = from + to; | |
2065 | if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize) | |
2066 | return 0; | |
2067 | ||
2068 | head = page_buffers(page); | |
2069 | bh = head; | |
2070 | block_start = 0; | |
2071 | do { | |
2072 | block_end = block_start + blocksize; | |
2073 | if (block_end > from && block_start < to) { | |
2074 | if (!buffer_uptodate(bh)) { | |
2075 | ret = 0; | |
2076 | break; | |
2077 | } | |
2078 | if (block_end >= to) | |
2079 | break; | |
2080 | } | |
2081 | block_start = block_end; | |
2082 | bh = bh->b_this_page; | |
2083 | } while (bh != head); | |
2084 | ||
2085 | return ret; | |
2086 | } | |
2087 | EXPORT_SYMBOL(block_is_partially_uptodate); | |
2088 | ||
1da177e4 LT |
2089 | /* |
2090 | * Generic "read page" function for block devices that have the normal | |
2091 | * get_block functionality. This is most of the block device filesystems. | |
2092 | * Reads the page asynchronously --- the unlock_buffer() and | |
2093 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2094 | * page struct once IO has completed. | |
2095 | */ | |
2096 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2097 | { | |
2098 | struct inode *inode = page->mapping->host; | |
2099 | sector_t iblock, lblock; | |
2100 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
2101 | unsigned int blocksize; | |
2102 | int nr, i; | |
2103 | int fully_mapped = 1; | |
2104 | ||
cd7619d6 | 2105 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
2106 | blocksize = 1 << inode->i_blkbits; |
2107 | if (!page_has_buffers(page)) | |
2108 | create_empty_buffers(page, blocksize, 0); | |
2109 | head = page_buffers(page); | |
2110 | ||
2111 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
2112 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; | |
2113 | bh = head; | |
2114 | nr = 0; | |
2115 | i = 0; | |
2116 | ||
2117 | do { | |
2118 | if (buffer_uptodate(bh)) | |
2119 | continue; | |
2120 | ||
2121 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2122 | int err = 0; |
2123 | ||
1da177e4 LT |
2124 | fully_mapped = 0; |
2125 | if (iblock < lblock) { | |
b0cf2321 | 2126 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2127 | err = get_block(inode, iblock, bh, 0); |
2128 | if (err) | |
1da177e4 LT |
2129 | SetPageError(page); |
2130 | } | |
2131 | if (!buffer_mapped(bh)) { | |
eebd2aa3 | 2132 | zero_user(page, i * blocksize, blocksize); |
c64610ba AM |
2133 | if (!err) |
2134 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2135 | continue; |
2136 | } | |
2137 | /* | |
2138 | * get_block() might have updated the buffer | |
2139 | * synchronously | |
2140 | */ | |
2141 | if (buffer_uptodate(bh)) | |
2142 | continue; | |
2143 | } | |
2144 | arr[nr++] = bh; | |
2145 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2146 | ||
2147 | if (fully_mapped) | |
2148 | SetPageMappedToDisk(page); | |
2149 | ||
2150 | if (!nr) { | |
2151 | /* | |
2152 | * All buffers are uptodate - we can set the page uptodate | |
2153 | * as well. But not if get_block() returned an error. | |
2154 | */ | |
2155 | if (!PageError(page)) | |
2156 | SetPageUptodate(page); | |
2157 | unlock_page(page); | |
2158 | return 0; | |
2159 | } | |
2160 | ||
2161 | /* Stage two: lock the buffers */ | |
2162 | for (i = 0; i < nr; i++) { | |
2163 | bh = arr[i]; | |
2164 | lock_buffer(bh); | |
2165 | mark_buffer_async_read(bh); | |
2166 | } | |
2167 | ||
2168 | /* | |
2169 | * Stage 3: start the IO. Check for uptodateness | |
2170 | * inside the buffer lock in case another process reading | |
2171 | * the underlying blockdev brought it uptodate (the sct fix). | |
2172 | */ | |
2173 | for (i = 0; i < nr; i++) { | |
2174 | bh = arr[i]; | |
2175 | if (buffer_uptodate(bh)) | |
2176 | end_buffer_async_read(bh, 1); | |
2177 | else | |
2178 | submit_bh(READ, bh); | |
2179 | } | |
2180 | return 0; | |
2181 | } | |
2182 | ||
2183 | /* utility function for filesystems that need to do work on expanding | |
89e10787 | 2184 | * truncates. Uses filesystem pagecache writes to allow the filesystem to |
1da177e4 LT |
2185 | * deal with the hole. |
2186 | */ | |
89e10787 | 2187 | int generic_cont_expand_simple(struct inode *inode, loff_t size) |
1da177e4 LT |
2188 | { |
2189 | struct address_space *mapping = inode->i_mapping; | |
2190 | struct page *page; | |
89e10787 | 2191 | void *fsdata; |
05eb0b51 | 2192 | unsigned long limit; |
1da177e4 LT |
2193 | int err; |
2194 | ||
2195 | err = -EFBIG; | |
2196 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
2197 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { | |
2198 | send_sig(SIGXFSZ, current, 0); | |
2199 | goto out; | |
2200 | } | |
2201 | if (size > inode->i_sb->s_maxbytes) | |
2202 | goto out; | |
2203 | ||
89e10787 NP |
2204 | err = pagecache_write_begin(NULL, mapping, size, 0, |
2205 | AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND, | |
2206 | &page, &fsdata); | |
2207 | if (err) | |
05eb0b51 | 2208 | goto out; |
05eb0b51 | 2209 | |
89e10787 NP |
2210 | err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata); |
2211 | BUG_ON(err > 0); | |
05eb0b51 | 2212 | |
1da177e4 LT |
2213 | out: |
2214 | return err; | |
2215 | } | |
2216 | ||
f1e3af72 AB |
2217 | static int cont_expand_zero(struct file *file, struct address_space *mapping, |
2218 | loff_t pos, loff_t *bytes) | |
1da177e4 | 2219 | { |
1da177e4 | 2220 | struct inode *inode = mapping->host; |
1da177e4 | 2221 | unsigned blocksize = 1 << inode->i_blkbits; |
89e10787 NP |
2222 | struct page *page; |
2223 | void *fsdata; | |
2224 | pgoff_t index, curidx; | |
2225 | loff_t curpos; | |
2226 | unsigned zerofrom, offset, len; | |
2227 | int err = 0; | |
1da177e4 | 2228 | |
89e10787 NP |
2229 | index = pos >> PAGE_CACHE_SHIFT; |
2230 | offset = pos & ~PAGE_CACHE_MASK; | |
2231 | ||
2232 | while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) { | |
2233 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 LT |
2234 | if (zerofrom & (blocksize-1)) { |
2235 | *bytes |= (blocksize-1); | |
2236 | (*bytes)++; | |
2237 | } | |
89e10787 | 2238 | len = PAGE_CACHE_SIZE - zerofrom; |
1da177e4 | 2239 | |
89e10787 NP |
2240 | err = pagecache_write_begin(file, mapping, curpos, len, |
2241 | AOP_FLAG_UNINTERRUPTIBLE, | |
2242 | &page, &fsdata); | |
2243 | if (err) | |
2244 | goto out; | |
eebd2aa3 | 2245 | zero_user(page, zerofrom, len); |
89e10787 NP |
2246 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2247 | page, fsdata); | |
2248 | if (err < 0) | |
2249 | goto out; | |
2250 | BUG_ON(err != len); | |
2251 | err = 0; | |
061e9746 OH |
2252 | |
2253 | balance_dirty_pages_ratelimited(mapping); | |
89e10787 | 2254 | } |
1da177e4 | 2255 | |
89e10787 NP |
2256 | /* page covers the boundary, find the boundary offset */ |
2257 | if (index == curidx) { | |
2258 | zerofrom = curpos & ~PAGE_CACHE_MASK; | |
1da177e4 | 2259 | /* if we will expand the thing last block will be filled */ |
89e10787 NP |
2260 | if (offset <= zerofrom) { |
2261 | goto out; | |
2262 | } | |
2263 | if (zerofrom & (blocksize-1)) { | |
1da177e4 LT |
2264 | *bytes |= (blocksize-1); |
2265 | (*bytes)++; | |
2266 | } | |
89e10787 | 2267 | len = offset - zerofrom; |
1da177e4 | 2268 | |
89e10787 NP |
2269 | err = pagecache_write_begin(file, mapping, curpos, len, |
2270 | AOP_FLAG_UNINTERRUPTIBLE, | |
2271 | &page, &fsdata); | |
2272 | if (err) | |
2273 | goto out; | |
eebd2aa3 | 2274 | zero_user(page, zerofrom, len); |
89e10787 NP |
2275 | err = pagecache_write_end(file, mapping, curpos, len, len, |
2276 | page, fsdata); | |
2277 | if (err < 0) | |
2278 | goto out; | |
2279 | BUG_ON(err != len); | |
2280 | err = 0; | |
1da177e4 | 2281 | } |
89e10787 NP |
2282 | out: |
2283 | return err; | |
2284 | } | |
2285 | ||
2286 | /* | |
2287 | * For moronic filesystems that do not allow holes in file. | |
2288 | * We may have to extend the file. | |
2289 | */ | |
2290 | int cont_write_begin(struct file *file, struct address_space *mapping, | |
2291 | loff_t pos, unsigned len, unsigned flags, | |
2292 | struct page **pagep, void **fsdata, | |
2293 | get_block_t *get_block, loff_t *bytes) | |
2294 | { | |
2295 | struct inode *inode = mapping->host; | |
2296 | unsigned blocksize = 1 << inode->i_blkbits; | |
2297 | unsigned zerofrom; | |
2298 | int err; | |
2299 | ||
2300 | err = cont_expand_zero(file, mapping, pos, bytes); | |
2301 | if (err) | |
2302 | goto out; | |
2303 | ||
2304 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2305 | if (pos+len > *bytes && zerofrom & (blocksize-1)) { | |
2306 | *bytes |= (blocksize-1); | |
2307 | (*bytes)++; | |
1da177e4 | 2308 | } |
1da177e4 | 2309 | |
89e10787 NP |
2310 | *pagep = NULL; |
2311 | err = block_write_begin(file, mapping, pos, len, | |
2312 | flags, pagep, fsdata, get_block); | |
1da177e4 | 2313 | out: |
89e10787 | 2314 | return err; |
1da177e4 LT |
2315 | } |
2316 | ||
2317 | int block_prepare_write(struct page *page, unsigned from, unsigned to, | |
2318 | get_block_t *get_block) | |
2319 | { | |
2320 | struct inode *inode = page->mapping->host; | |
2321 | int err = __block_prepare_write(inode, page, from, to, get_block); | |
2322 | if (err) | |
2323 | ClearPageUptodate(page); | |
2324 | return err; | |
2325 | } | |
2326 | ||
2327 | int block_commit_write(struct page *page, unsigned from, unsigned to) | |
2328 | { | |
2329 | struct inode *inode = page->mapping->host; | |
2330 | __block_commit_write(inode,page,from,to); | |
2331 | return 0; | |
2332 | } | |
2333 | ||
54171690 DC |
2334 | /* |
2335 | * block_page_mkwrite() is not allowed to change the file size as it gets | |
2336 | * called from a page fault handler when a page is first dirtied. Hence we must | |
2337 | * be careful to check for EOF conditions here. We set the page up correctly | |
2338 | * for a written page which means we get ENOSPC checking when writing into | |
2339 | * holes and correct delalloc and unwritten extent mapping on filesystems that | |
2340 | * support these features. | |
2341 | * | |
2342 | * We are not allowed to take the i_mutex here so we have to play games to | |
2343 | * protect against truncate races as the page could now be beyond EOF. Because | |
2344 | * vmtruncate() writes the inode size before removing pages, once we have the | |
2345 | * page lock we can determine safely if the page is beyond EOF. If it is not | |
2346 | * beyond EOF, then the page is guaranteed safe against truncation until we | |
2347 | * unlock the page. | |
2348 | */ | |
2349 | int | |
c2ec175c | 2350 | block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf, |
54171690 DC |
2351 | get_block_t get_block) |
2352 | { | |
c2ec175c | 2353 | struct page *page = vmf->page; |
54171690 DC |
2354 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
2355 | unsigned long end; | |
2356 | loff_t size; | |
56a76f82 | 2357 | int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */ |
54171690 DC |
2358 | |
2359 | lock_page(page); | |
2360 | size = i_size_read(inode); | |
2361 | if ((page->mapping != inode->i_mapping) || | |
18336338 | 2362 | (page_offset(page) > size)) { |
54171690 DC |
2363 | /* page got truncated out from underneath us */ |
2364 | goto out_unlock; | |
2365 | } | |
2366 | ||
2367 | /* page is wholly or partially inside EOF */ | |
2368 | if (((page->index + 1) << PAGE_CACHE_SHIFT) > size) | |
2369 | end = size & ~PAGE_CACHE_MASK; | |
2370 | else | |
2371 | end = PAGE_CACHE_SIZE; | |
2372 | ||
2373 | ret = block_prepare_write(page, 0, end, get_block); | |
2374 | if (!ret) | |
2375 | ret = block_commit_write(page, 0, end); | |
2376 | ||
56a76f82 NP |
2377 | if (unlikely(ret)) { |
2378 | if (ret == -ENOMEM) | |
2379 | ret = VM_FAULT_OOM; | |
2380 | else /* -ENOSPC, -EIO, etc */ | |
2381 | ret = VM_FAULT_SIGBUS; | |
2382 | } | |
c2ec175c | 2383 | |
56a76f82 | 2384 | out_unlock: |
54171690 DC |
2385 | unlock_page(page); |
2386 | return ret; | |
2387 | } | |
1da177e4 LT |
2388 | |
2389 | /* | |
03158cd7 | 2390 | * nobh_write_begin()'s prereads are special: the buffer_heads are freed |
1da177e4 LT |
2391 | * immediately, while under the page lock. So it needs a special end_io |
2392 | * handler which does not touch the bh after unlocking it. | |
1da177e4 LT |
2393 | */ |
2394 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2395 | { | |
68671f35 | 2396 | __end_buffer_read_notouch(bh, uptodate); |
1da177e4 LT |
2397 | } |
2398 | ||
03158cd7 NP |
2399 | /* |
2400 | * Attach the singly-linked list of buffers created by nobh_write_begin, to | |
2401 | * the page (converting it to circular linked list and taking care of page | |
2402 | * dirty races). | |
2403 | */ | |
2404 | static void attach_nobh_buffers(struct page *page, struct buffer_head *head) | |
2405 | { | |
2406 | struct buffer_head *bh; | |
2407 | ||
2408 | BUG_ON(!PageLocked(page)); | |
2409 | ||
2410 | spin_lock(&page->mapping->private_lock); | |
2411 | bh = head; | |
2412 | do { | |
2413 | if (PageDirty(page)) | |
2414 | set_buffer_dirty(bh); | |
2415 | if (!bh->b_this_page) | |
2416 | bh->b_this_page = head; | |
2417 | bh = bh->b_this_page; | |
2418 | } while (bh != head); | |
2419 | attach_page_buffers(page, head); | |
2420 | spin_unlock(&page->mapping->private_lock); | |
2421 | } | |
2422 | ||
1da177e4 LT |
2423 | /* |
2424 | * On entry, the page is fully not uptodate. | |
2425 | * On exit the page is fully uptodate in the areas outside (from,to) | |
2426 | */ | |
03158cd7 NP |
2427 | int nobh_write_begin(struct file *file, struct address_space *mapping, |
2428 | loff_t pos, unsigned len, unsigned flags, | |
2429 | struct page **pagep, void **fsdata, | |
1da177e4 LT |
2430 | get_block_t *get_block) |
2431 | { | |
03158cd7 | 2432 | struct inode *inode = mapping->host; |
1da177e4 LT |
2433 | const unsigned blkbits = inode->i_blkbits; |
2434 | const unsigned blocksize = 1 << blkbits; | |
a4b0672d | 2435 | struct buffer_head *head, *bh; |
03158cd7 NP |
2436 | struct page *page; |
2437 | pgoff_t index; | |
2438 | unsigned from, to; | |
1da177e4 | 2439 | unsigned block_in_page; |
a4b0672d | 2440 | unsigned block_start, block_end; |
1da177e4 | 2441 | sector_t block_in_file; |
1da177e4 | 2442 | int nr_reads = 0; |
1da177e4 LT |
2443 | int ret = 0; |
2444 | int is_mapped_to_disk = 1; | |
1da177e4 | 2445 | |
03158cd7 NP |
2446 | index = pos >> PAGE_CACHE_SHIFT; |
2447 | from = pos & (PAGE_CACHE_SIZE - 1); | |
2448 | to = from + len; | |
2449 | ||
54566b2c | 2450 | page = grab_cache_page_write_begin(mapping, index, flags); |
03158cd7 NP |
2451 | if (!page) |
2452 | return -ENOMEM; | |
2453 | *pagep = page; | |
2454 | *fsdata = NULL; | |
2455 | ||
2456 | if (page_has_buffers(page)) { | |
2457 | unlock_page(page); | |
2458 | page_cache_release(page); | |
2459 | *pagep = NULL; | |
2460 | return block_write_begin(file, mapping, pos, len, flags, pagep, | |
2461 | fsdata, get_block); | |
2462 | } | |
a4b0672d | 2463 | |
1da177e4 LT |
2464 | if (PageMappedToDisk(page)) |
2465 | return 0; | |
2466 | ||
a4b0672d NP |
2467 | /* |
2468 | * Allocate buffers so that we can keep track of state, and potentially | |
2469 | * attach them to the page if an error occurs. In the common case of | |
2470 | * no error, they will just be freed again without ever being attached | |
2471 | * to the page (which is all OK, because we're under the page lock). | |
2472 | * | |
2473 | * Be careful: the buffer linked list is a NULL terminated one, rather | |
2474 | * than the circular one we're used to. | |
2475 | */ | |
2476 | head = alloc_page_buffers(page, blocksize, 0); | |
03158cd7 NP |
2477 | if (!head) { |
2478 | ret = -ENOMEM; | |
2479 | goto out_release; | |
2480 | } | |
a4b0672d | 2481 | |
1da177e4 | 2482 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); |
1da177e4 LT |
2483 | |
2484 | /* | |
2485 | * We loop across all blocks in the page, whether or not they are | |
2486 | * part of the affected region. This is so we can discover if the | |
2487 | * page is fully mapped-to-disk. | |
2488 | */ | |
a4b0672d | 2489 | for (block_start = 0, block_in_page = 0, bh = head; |
1da177e4 | 2490 | block_start < PAGE_CACHE_SIZE; |
a4b0672d | 2491 | block_in_page++, block_start += blocksize, bh = bh->b_this_page) { |
1da177e4 LT |
2492 | int create; |
2493 | ||
a4b0672d NP |
2494 | block_end = block_start + blocksize; |
2495 | bh->b_state = 0; | |
1da177e4 LT |
2496 | create = 1; |
2497 | if (block_start >= to) | |
2498 | create = 0; | |
2499 | ret = get_block(inode, block_in_file + block_in_page, | |
a4b0672d | 2500 | bh, create); |
1da177e4 LT |
2501 | if (ret) |
2502 | goto failed; | |
a4b0672d | 2503 | if (!buffer_mapped(bh)) |
1da177e4 | 2504 | is_mapped_to_disk = 0; |
a4b0672d NP |
2505 | if (buffer_new(bh)) |
2506 | unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); | |
2507 | if (PageUptodate(page)) { | |
2508 | set_buffer_uptodate(bh); | |
1da177e4 | 2509 | continue; |
a4b0672d NP |
2510 | } |
2511 | if (buffer_new(bh) || !buffer_mapped(bh)) { | |
eebd2aa3 CL |
2512 | zero_user_segments(page, block_start, from, |
2513 | to, block_end); | |
1da177e4 LT |
2514 | continue; |
2515 | } | |
a4b0672d | 2516 | if (buffer_uptodate(bh)) |
1da177e4 LT |
2517 | continue; /* reiserfs does this */ |
2518 | if (block_start < from || block_end > to) { | |
a4b0672d NP |
2519 | lock_buffer(bh); |
2520 | bh->b_end_io = end_buffer_read_nobh; | |
2521 | submit_bh(READ, bh); | |
2522 | nr_reads++; | |
1da177e4 LT |
2523 | } |
2524 | } | |
2525 | ||
2526 | if (nr_reads) { | |
1da177e4 LT |
2527 | /* |
2528 | * The page is locked, so these buffers are protected from | |
2529 | * any VM or truncate activity. Hence we don't need to care | |
2530 | * for the buffer_head refcounts. | |
2531 | */ | |
a4b0672d | 2532 | for (bh = head; bh; bh = bh->b_this_page) { |
1da177e4 LT |
2533 | wait_on_buffer(bh); |
2534 | if (!buffer_uptodate(bh)) | |
2535 | ret = -EIO; | |
1da177e4 LT |
2536 | } |
2537 | if (ret) | |
2538 | goto failed; | |
2539 | } | |
2540 | ||
2541 | if (is_mapped_to_disk) | |
2542 | SetPageMappedToDisk(page); | |
1da177e4 | 2543 | |
03158cd7 | 2544 | *fsdata = head; /* to be released by nobh_write_end */ |
a4b0672d | 2545 | |
1da177e4 LT |
2546 | return 0; |
2547 | ||
2548 | failed: | |
03158cd7 | 2549 | BUG_ON(!ret); |
1da177e4 | 2550 | /* |
a4b0672d NP |
2551 | * Error recovery is a bit difficult. We need to zero out blocks that |
2552 | * were newly allocated, and dirty them to ensure they get written out. | |
2553 | * Buffers need to be attached to the page at this point, otherwise | |
2554 | * the handling of potential IO errors during writeout would be hard | |
2555 | * (could try doing synchronous writeout, but what if that fails too?) | |
1da177e4 | 2556 | */ |
03158cd7 NP |
2557 | attach_nobh_buffers(page, head); |
2558 | page_zero_new_buffers(page, from, to); | |
a4b0672d | 2559 | |
03158cd7 NP |
2560 | out_release: |
2561 | unlock_page(page); | |
2562 | page_cache_release(page); | |
2563 | *pagep = NULL; | |
a4b0672d | 2564 | |
03158cd7 NP |
2565 | if (pos + len > inode->i_size) |
2566 | vmtruncate(inode, inode->i_size); | |
a4b0672d | 2567 | |
1da177e4 LT |
2568 | return ret; |
2569 | } | |
03158cd7 | 2570 | EXPORT_SYMBOL(nobh_write_begin); |
1da177e4 | 2571 | |
03158cd7 NP |
2572 | int nobh_write_end(struct file *file, struct address_space *mapping, |
2573 | loff_t pos, unsigned len, unsigned copied, | |
2574 | struct page *page, void *fsdata) | |
1da177e4 LT |
2575 | { |
2576 | struct inode *inode = page->mapping->host; | |
efdc3131 | 2577 | struct buffer_head *head = fsdata; |
03158cd7 | 2578 | struct buffer_head *bh; |
5b41e74a | 2579 | BUG_ON(fsdata != NULL && page_has_buffers(page)); |
1da177e4 | 2580 | |
d4cf109f | 2581 | if (unlikely(copied < len) && head) |
5b41e74a DM |
2582 | attach_nobh_buffers(page, head); |
2583 | if (page_has_buffers(page)) | |
2584 | return generic_write_end(file, mapping, pos, len, | |
2585 | copied, page, fsdata); | |
a4b0672d | 2586 | |
22c8ca78 | 2587 | SetPageUptodate(page); |
1da177e4 | 2588 | set_page_dirty(page); |
03158cd7 NP |
2589 | if (pos+copied > inode->i_size) { |
2590 | i_size_write(inode, pos+copied); | |
1da177e4 LT |
2591 | mark_inode_dirty(inode); |
2592 | } | |
03158cd7 NP |
2593 | |
2594 | unlock_page(page); | |
2595 | page_cache_release(page); | |
2596 | ||
03158cd7 NP |
2597 | while (head) { |
2598 | bh = head; | |
2599 | head = head->b_this_page; | |
2600 | free_buffer_head(bh); | |
2601 | } | |
2602 | ||
2603 | return copied; | |
1da177e4 | 2604 | } |
03158cd7 | 2605 | EXPORT_SYMBOL(nobh_write_end); |
1da177e4 LT |
2606 | |
2607 | /* | |
2608 | * nobh_writepage() - based on block_full_write_page() except | |
2609 | * that it tries to operate without attaching bufferheads to | |
2610 | * the page. | |
2611 | */ | |
2612 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2613 | struct writeback_control *wbc) | |
2614 | { | |
2615 | struct inode * const inode = page->mapping->host; | |
2616 | loff_t i_size = i_size_read(inode); | |
2617 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2618 | unsigned offset; | |
1da177e4 LT |
2619 | int ret; |
2620 | ||
2621 | /* Is the page fully inside i_size? */ | |
2622 | if (page->index < end_index) | |
2623 | goto out; | |
2624 | ||
2625 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2626 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2627 | if (page->index >= end_index+1 || !offset) { | |
2628 | /* | |
2629 | * The page may have dirty, unmapped buffers. For example, | |
2630 | * they may have been added in ext3_writepage(). Make them | |
2631 | * freeable here, so the page does not leak. | |
2632 | */ | |
2633 | #if 0 | |
2634 | /* Not really sure about this - do we need this ? */ | |
2635 | if (page->mapping->a_ops->invalidatepage) | |
2636 | page->mapping->a_ops->invalidatepage(page, offset); | |
2637 | #endif | |
2638 | unlock_page(page); | |
2639 | return 0; /* don't care */ | |
2640 | } | |
2641 | ||
2642 | /* | |
2643 | * The page straddles i_size. It must be zeroed out on each and every | |
2644 | * writepage invocation because it may be mmapped. "A file is mapped | |
2645 | * in multiples of the page size. For a file that is not a multiple of | |
2646 | * the page size, the remaining memory is zeroed when mapped, and | |
2647 | * writes to that region are not written out to the file." | |
2648 | */ | |
eebd2aa3 | 2649 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
1da177e4 LT |
2650 | out: |
2651 | ret = mpage_writepage(page, get_block, wbc); | |
2652 | if (ret == -EAGAIN) | |
2653 | ret = __block_write_full_page(inode, page, get_block, wbc); | |
2654 | return ret; | |
2655 | } | |
2656 | EXPORT_SYMBOL(nobh_writepage); | |
2657 | ||
03158cd7 NP |
2658 | int nobh_truncate_page(struct address_space *mapping, |
2659 | loff_t from, get_block_t *get_block) | |
1da177e4 | 2660 | { |
1da177e4 LT |
2661 | pgoff_t index = from >> PAGE_CACHE_SHIFT; |
2662 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
03158cd7 NP |
2663 | unsigned blocksize; |
2664 | sector_t iblock; | |
2665 | unsigned length, pos; | |
2666 | struct inode *inode = mapping->host; | |
1da177e4 | 2667 | struct page *page; |
03158cd7 NP |
2668 | struct buffer_head map_bh; |
2669 | int err; | |
1da177e4 | 2670 | |
03158cd7 NP |
2671 | blocksize = 1 << inode->i_blkbits; |
2672 | length = offset & (blocksize - 1); | |
2673 | ||
2674 | /* Block boundary? Nothing to do */ | |
2675 | if (!length) | |
2676 | return 0; | |
2677 | ||
2678 | length = blocksize - length; | |
2679 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
1da177e4 | 2680 | |
1da177e4 | 2681 | page = grab_cache_page(mapping, index); |
03158cd7 | 2682 | err = -ENOMEM; |
1da177e4 LT |
2683 | if (!page) |
2684 | goto out; | |
2685 | ||
03158cd7 NP |
2686 | if (page_has_buffers(page)) { |
2687 | has_buffers: | |
2688 | unlock_page(page); | |
2689 | page_cache_release(page); | |
2690 | return block_truncate_page(mapping, from, get_block); | |
2691 | } | |
2692 | ||
2693 | /* Find the buffer that contains "offset" */ | |
2694 | pos = blocksize; | |
2695 | while (offset >= pos) { | |
2696 | iblock++; | |
2697 | pos += blocksize; | |
2698 | } | |
2699 | ||
2700 | err = get_block(inode, iblock, &map_bh, 0); | |
2701 | if (err) | |
2702 | goto unlock; | |
2703 | /* unmapped? It's a hole - nothing to do */ | |
2704 | if (!buffer_mapped(&map_bh)) | |
2705 | goto unlock; | |
2706 | ||
2707 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2708 | if (!PageUptodate(page)) { | |
2709 | err = mapping->a_ops->readpage(NULL, page); | |
2710 | if (err) { | |
2711 | page_cache_release(page); | |
2712 | goto out; | |
2713 | } | |
2714 | lock_page(page); | |
2715 | if (!PageUptodate(page)) { | |
2716 | err = -EIO; | |
2717 | goto unlock; | |
2718 | } | |
2719 | if (page_has_buffers(page)) | |
2720 | goto has_buffers; | |
1da177e4 | 2721 | } |
eebd2aa3 | 2722 | zero_user(page, offset, length); |
03158cd7 NP |
2723 | set_page_dirty(page); |
2724 | err = 0; | |
2725 | ||
2726 | unlock: | |
1da177e4 LT |
2727 | unlock_page(page); |
2728 | page_cache_release(page); | |
2729 | out: | |
03158cd7 | 2730 | return err; |
1da177e4 LT |
2731 | } |
2732 | EXPORT_SYMBOL(nobh_truncate_page); | |
2733 | ||
2734 | int block_truncate_page(struct address_space *mapping, | |
2735 | loff_t from, get_block_t *get_block) | |
2736 | { | |
2737 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2738 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2739 | unsigned blocksize; | |
54b21a79 | 2740 | sector_t iblock; |
1da177e4 LT |
2741 | unsigned length, pos; |
2742 | struct inode *inode = mapping->host; | |
2743 | struct page *page; | |
2744 | struct buffer_head *bh; | |
1da177e4 LT |
2745 | int err; |
2746 | ||
2747 | blocksize = 1 << inode->i_blkbits; | |
2748 | length = offset & (blocksize - 1); | |
2749 | ||
2750 | /* Block boundary? Nothing to do */ | |
2751 | if (!length) | |
2752 | return 0; | |
2753 | ||
2754 | length = blocksize - length; | |
54b21a79 | 2755 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2756 | |
2757 | page = grab_cache_page(mapping, index); | |
2758 | err = -ENOMEM; | |
2759 | if (!page) | |
2760 | goto out; | |
2761 | ||
2762 | if (!page_has_buffers(page)) | |
2763 | create_empty_buffers(page, blocksize, 0); | |
2764 | ||
2765 | /* Find the buffer that contains "offset" */ | |
2766 | bh = page_buffers(page); | |
2767 | pos = blocksize; | |
2768 | while (offset >= pos) { | |
2769 | bh = bh->b_this_page; | |
2770 | iblock++; | |
2771 | pos += blocksize; | |
2772 | } | |
2773 | ||
2774 | err = 0; | |
2775 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2776 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2777 | err = get_block(inode, iblock, bh, 0); |
2778 | if (err) | |
2779 | goto unlock; | |
2780 | /* unmapped? It's a hole - nothing to do */ | |
2781 | if (!buffer_mapped(bh)) | |
2782 | goto unlock; | |
2783 | } | |
2784 | ||
2785 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2786 | if (PageUptodate(page)) | |
2787 | set_buffer_uptodate(bh); | |
2788 | ||
33a266dd | 2789 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) { |
1da177e4 LT |
2790 | err = -EIO; |
2791 | ll_rw_block(READ, 1, &bh); | |
2792 | wait_on_buffer(bh); | |
2793 | /* Uhhuh. Read error. Complain and punt. */ | |
2794 | if (!buffer_uptodate(bh)) | |
2795 | goto unlock; | |
2796 | } | |
2797 | ||
eebd2aa3 | 2798 | zero_user(page, offset, length); |
1da177e4 LT |
2799 | mark_buffer_dirty(bh); |
2800 | err = 0; | |
2801 | ||
2802 | unlock: | |
2803 | unlock_page(page); | |
2804 | page_cache_release(page); | |
2805 | out: | |
2806 | return err; | |
2807 | } | |
2808 | ||
2809 | /* | |
2810 | * The generic ->writepage function for buffer-backed address_spaces | |
2811 | */ | |
2812 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2813 | struct writeback_control *wbc) | |
2814 | { | |
2815 | struct inode * const inode = page->mapping->host; | |
2816 | loff_t i_size = i_size_read(inode); | |
2817 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2818 | unsigned offset; | |
1da177e4 LT |
2819 | |
2820 | /* Is the page fully inside i_size? */ | |
2821 | if (page->index < end_index) | |
2822 | return __block_write_full_page(inode, page, get_block, wbc); | |
2823 | ||
2824 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2825 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2826 | if (page->index >= end_index+1 || !offset) { | |
2827 | /* | |
2828 | * The page may have dirty, unmapped buffers. For example, | |
2829 | * they may have been added in ext3_writepage(). Make them | |
2830 | * freeable here, so the page does not leak. | |
2831 | */ | |
aaa4059b | 2832 | do_invalidatepage(page, 0); |
1da177e4 LT |
2833 | unlock_page(page); |
2834 | return 0; /* don't care */ | |
2835 | } | |
2836 | ||
2837 | /* | |
2838 | * The page straddles i_size. It must be zeroed out on each and every | |
2839 | * writepage invokation because it may be mmapped. "A file is mapped | |
2840 | * in multiples of the page size. For a file that is not a multiple of | |
2841 | * the page size, the remaining memory is zeroed when mapped, and | |
2842 | * writes to that region are not written out to the file." | |
2843 | */ | |
eebd2aa3 | 2844 | zero_user_segment(page, offset, PAGE_CACHE_SIZE); |
1da177e4 LT |
2845 | return __block_write_full_page(inode, page, get_block, wbc); |
2846 | } | |
2847 | ||
2848 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, | |
2849 | get_block_t *get_block) | |
2850 | { | |
2851 | struct buffer_head tmp; | |
2852 | struct inode *inode = mapping->host; | |
2853 | tmp.b_state = 0; | |
2854 | tmp.b_blocknr = 0; | |
b0cf2321 | 2855 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2856 | get_block(inode, block, &tmp, 0); |
2857 | return tmp.b_blocknr; | |
2858 | } | |
2859 | ||
6712ecf8 | 2860 | static void end_bio_bh_io_sync(struct bio *bio, int err) |
1da177e4 LT |
2861 | { |
2862 | struct buffer_head *bh = bio->bi_private; | |
2863 | ||
1da177e4 LT |
2864 | if (err == -EOPNOTSUPP) { |
2865 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
2866 | set_bit(BH_Eopnotsupp, &bh->b_state); | |
2867 | } | |
2868 | ||
08bafc03 KM |
2869 | if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags))) |
2870 | set_bit(BH_Quiet, &bh->b_state); | |
2871 | ||
1da177e4 LT |
2872 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); |
2873 | bio_put(bio); | |
1da177e4 LT |
2874 | } |
2875 | ||
2876 | int submit_bh(int rw, struct buffer_head * bh) | |
2877 | { | |
2878 | struct bio *bio; | |
2879 | int ret = 0; | |
2880 | ||
2881 | BUG_ON(!buffer_locked(bh)); | |
2882 | BUG_ON(!buffer_mapped(bh)); | |
2883 | BUG_ON(!bh->b_end_io); | |
2884 | ||
48fd4f93 JA |
2885 | /* |
2886 | * Mask in barrier bit for a write (could be either a WRITE or a | |
2887 | * WRITE_SYNC | |
2888 | */ | |
2889 | if (buffer_ordered(bh) && (rw & WRITE)) | |
2890 | rw |= WRITE_BARRIER; | |
1da177e4 LT |
2891 | |
2892 | /* | |
48fd4f93 | 2893 | * Only clear out a write error when rewriting |
1da177e4 | 2894 | */ |
48fd4f93 | 2895 | if (test_set_buffer_req(bh) && (rw & WRITE)) |
1da177e4 LT |
2896 | clear_buffer_write_io_error(bh); |
2897 | ||
2898 | /* | |
2899 | * from here on down, it's all bio -- do the initial mapping, | |
2900 | * submit_bio -> generic_make_request may further map this bio around | |
2901 | */ | |
2902 | bio = bio_alloc(GFP_NOIO, 1); | |
2903 | ||
2904 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2905 | bio->bi_bdev = bh->b_bdev; | |
2906 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2907 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2908 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2909 | ||
2910 | bio->bi_vcnt = 1; | |
2911 | bio->bi_idx = 0; | |
2912 | bio->bi_size = bh->b_size; | |
2913 | ||
2914 | bio->bi_end_io = end_bio_bh_io_sync; | |
2915 | bio->bi_private = bh; | |
2916 | ||
2917 | bio_get(bio); | |
2918 | submit_bio(rw, bio); | |
2919 | ||
2920 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2921 | ret = -EOPNOTSUPP; | |
2922 | ||
2923 | bio_put(bio); | |
2924 | return ret; | |
2925 | } | |
2926 | ||
2927 | /** | |
2928 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
a7662236 | 2929 | * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) |
1da177e4 LT |
2930 | * @nr: number of &struct buffer_heads in the array |
2931 | * @bhs: array of pointers to &struct buffer_head | |
2932 | * | |
a7662236 JK |
2933 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
2934 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
2935 | * %SWRITE is like %WRITE only we make sure that the *current* data in buffers | |
2936 | * are sent to disk. The fourth %READA option is described in the documentation | |
2937 | * for generic_make_request() which ll_rw_block() calls. | |
1da177e4 LT |
2938 | * |
2939 | * This function drops any buffer that it cannot get a lock on (with the | |
a7662236 JK |
2940 | * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be |
2941 | * clean when doing a write request, and any buffer that appears to be | |
2942 | * up-to-date when doing read request. Further it marks as clean buffers that | |
2943 | * are processed for writing (the buffer cache won't assume that they are | |
2944 | * actually clean until the buffer gets unlocked). | |
1da177e4 LT |
2945 | * |
2946 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
2947 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
2948 | * any waiters. | |
2949 | * | |
2950 | * All of the buffers must be for the same device, and must also be a | |
2951 | * multiple of the current approved size for the device. | |
2952 | */ | |
2953 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
2954 | { | |
2955 | int i; | |
2956 | ||
2957 | for (i = 0; i < nr; i++) { | |
2958 | struct buffer_head *bh = bhs[i]; | |
2959 | ||
18ce3751 | 2960 | if (rw == SWRITE || rw == SWRITE_SYNC) |
a7662236 | 2961 | lock_buffer(bh); |
ca5de404 | 2962 | else if (!trylock_buffer(bh)) |
1da177e4 LT |
2963 | continue; |
2964 | ||
18ce3751 | 2965 | if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC) { |
1da177e4 | 2966 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 2967 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 2968 | get_bh(bh); |
18ce3751 JA |
2969 | if (rw == SWRITE_SYNC) |
2970 | submit_bh(WRITE_SYNC, bh); | |
2971 | else | |
2972 | submit_bh(WRITE, bh); | |
1da177e4 LT |
2973 | continue; |
2974 | } | |
2975 | } else { | |
1da177e4 | 2976 | if (!buffer_uptodate(bh)) { |
76c3073a | 2977 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 2978 | get_bh(bh); |
1da177e4 LT |
2979 | submit_bh(rw, bh); |
2980 | continue; | |
2981 | } | |
2982 | } | |
2983 | unlock_buffer(bh); | |
1da177e4 LT |
2984 | } |
2985 | } | |
2986 | ||
2987 | /* | |
2988 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
2989 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
2990 | * the buffer_head. | |
2991 | */ | |
2992 | int sync_dirty_buffer(struct buffer_head *bh) | |
2993 | { | |
2994 | int ret = 0; | |
2995 | ||
2996 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
2997 | lock_buffer(bh); | |
2998 | if (test_clear_buffer_dirty(bh)) { | |
2999 | get_bh(bh); | |
3000 | bh->b_end_io = end_buffer_write_sync; | |
78f707bf | 3001 | ret = submit_bh(WRITE, bh); |
1da177e4 LT |
3002 | wait_on_buffer(bh); |
3003 | if (buffer_eopnotsupp(bh)) { | |
3004 | clear_buffer_eopnotsupp(bh); | |
3005 | ret = -EOPNOTSUPP; | |
3006 | } | |
3007 | if (!ret && !buffer_uptodate(bh)) | |
3008 | ret = -EIO; | |
3009 | } else { | |
3010 | unlock_buffer(bh); | |
3011 | } | |
3012 | return ret; | |
3013 | } | |
3014 | ||
3015 | /* | |
3016 | * try_to_free_buffers() checks if all the buffers on this particular page | |
3017 | * are unused, and releases them if so. | |
3018 | * | |
3019 | * Exclusion against try_to_free_buffers may be obtained by either | |
3020 | * locking the page or by holding its mapping's private_lock. | |
3021 | * | |
3022 | * If the page is dirty but all the buffers are clean then we need to | |
3023 | * be sure to mark the page clean as well. This is because the page | |
3024 | * may be against a block device, and a later reattachment of buffers | |
3025 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
3026 | * filesystem data on the same device. | |
3027 | * | |
3028 | * The same applies to regular filesystem pages: if all the buffers are | |
3029 | * clean then we set the page clean and proceed. To do that, we require | |
3030 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
3031 | * private_lock. | |
3032 | * | |
3033 | * try_to_free_buffers() is non-blocking. | |
3034 | */ | |
3035 | static inline int buffer_busy(struct buffer_head *bh) | |
3036 | { | |
3037 | return atomic_read(&bh->b_count) | | |
3038 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
3039 | } | |
3040 | ||
3041 | static int | |
3042 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
3043 | { | |
3044 | struct buffer_head *head = page_buffers(page); | |
3045 | struct buffer_head *bh; | |
3046 | ||
3047 | bh = head; | |
3048 | do { | |
de7d5a3b | 3049 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
3050 | set_bit(AS_EIO, &page->mapping->flags); |
3051 | if (buffer_busy(bh)) | |
3052 | goto failed; | |
3053 | bh = bh->b_this_page; | |
3054 | } while (bh != head); | |
3055 | ||
3056 | do { | |
3057 | struct buffer_head *next = bh->b_this_page; | |
3058 | ||
535ee2fb | 3059 | if (bh->b_assoc_map) |
1da177e4 LT |
3060 | __remove_assoc_queue(bh); |
3061 | bh = next; | |
3062 | } while (bh != head); | |
3063 | *buffers_to_free = head; | |
3064 | __clear_page_buffers(page); | |
3065 | return 1; | |
3066 | failed: | |
3067 | return 0; | |
3068 | } | |
3069 | ||
3070 | int try_to_free_buffers(struct page *page) | |
3071 | { | |
3072 | struct address_space * const mapping = page->mapping; | |
3073 | struct buffer_head *buffers_to_free = NULL; | |
3074 | int ret = 0; | |
3075 | ||
3076 | BUG_ON(!PageLocked(page)); | |
ecdfc978 | 3077 | if (PageWriteback(page)) |
1da177e4 LT |
3078 | return 0; |
3079 | ||
3080 | if (mapping == NULL) { /* can this still happen? */ | |
3081 | ret = drop_buffers(page, &buffers_to_free); | |
3082 | goto out; | |
3083 | } | |
3084 | ||
3085 | spin_lock(&mapping->private_lock); | |
3086 | ret = drop_buffers(page, &buffers_to_free); | |
ecdfc978 LT |
3087 | |
3088 | /* | |
3089 | * If the filesystem writes its buffers by hand (eg ext3) | |
3090 | * then we can have clean buffers against a dirty page. We | |
3091 | * clean the page here; otherwise the VM will never notice | |
3092 | * that the filesystem did any IO at all. | |
3093 | * | |
3094 | * Also, during truncate, discard_buffer will have marked all | |
3095 | * the page's buffers clean. We discover that here and clean | |
3096 | * the page also. | |
87df7241 NP |
3097 | * |
3098 | * private_lock must be held over this entire operation in order | |
3099 | * to synchronise against __set_page_dirty_buffers and prevent the | |
3100 | * dirty bit from being lost. | |
ecdfc978 LT |
3101 | */ |
3102 | if (ret) | |
3103 | cancel_dirty_page(page, PAGE_CACHE_SIZE); | |
87df7241 | 3104 | spin_unlock(&mapping->private_lock); |
1da177e4 LT |
3105 | out: |
3106 | if (buffers_to_free) { | |
3107 | struct buffer_head *bh = buffers_to_free; | |
3108 | ||
3109 | do { | |
3110 | struct buffer_head *next = bh->b_this_page; | |
3111 | free_buffer_head(bh); | |
3112 | bh = next; | |
3113 | } while (bh != buffers_to_free); | |
3114 | } | |
3115 | return ret; | |
3116 | } | |
3117 | EXPORT_SYMBOL(try_to_free_buffers); | |
3118 | ||
3978d717 | 3119 | void block_sync_page(struct page *page) |
1da177e4 LT |
3120 | { |
3121 | struct address_space *mapping; | |
3122 | ||
3123 | smp_mb(); | |
3124 | mapping = page_mapping(page); | |
3125 | if (mapping) | |
3126 | blk_run_backing_dev(mapping->backing_dev_info, page); | |
1da177e4 LT |
3127 | } |
3128 | ||
3129 | /* | |
3130 | * There are no bdflush tunables left. But distributions are | |
3131 | * still running obsolete flush daemons, so we terminate them here. | |
3132 | * | |
3133 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
3134 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. | |
3135 | */ | |
bdc480e3 | 3136 | SYSCALL_DEFINE2(bdflush, int, func, long, data) |
1da177e4 LT |
3137 | { |
3138 | static int msg_count; | |
3139 | ||
3140 | if (!capable(CAP_SYS_ADMIN)) | |
3141 | return -EPERM; | |
3142 | ||
3143 | if (msg_count < 5) { | |
3144 | msg_count++; | |
3145 | printk(KERN_INFO | |
3146 | "warning: process `%s' used the obsolete bdflush" | |
3147 | " system call\n", current->comm); | |
3148 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3149 | } | |
3150 | ||
3151 | if (func == 1) | |
3152 | do_exit(0); | |
3153 | return 0; | |
3154 | } | |
3155 | ||
3156 | /* | |
3157 | * Buffer-head allocation | |
3158 | */ | |
e18b890b | 3159 | static struct kmem_cache *bh_cachep; |
1da177e4 LT |
3160 | |
3161 | /* | |
3162 | * Once the number of bh's in the machine exceeds this level, we start | |
3163 | * stripping them in writeback. | |
3164 | */ | |
3165 | static int max_buffer_heads; | |
3166 | ||
3167 | int buffer_heads_over_limit; | |
3168 | ||
3169 | struct bh_accounting { | |
3170 | int nr; /* Number of live bh's */ | |
3171 | int ratelimit; /* Limit cacheline bouncing */ | |
3172 | }; | |
3173 | ||
3174 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3175 | ||
3176 | static void recalc_bh_state(void) | |
3177 | { | |
3178 | int i; | |
3179 | int tot = 0; | |
3180 | ||
3181 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) | |
3182 | return; | |
3183 | __get_cpu_var(bh_accounting).ratelimit = 0; | |
8a143426 | 3184 | for_each_online_cpu(i) |
1da177e4 LT |
3185 | tot += per_cpu(bh_accounting, i).nr; |
3186 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3187 | } | |
3188 | ||
dd0fc66f | 3189 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 | 3190 | { |
488514d1 | 3191 | struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); |
1da177e4 | 3192 | if (ret) { |
a35afb83 | 3193 | INIT_LIST_HEAD(&ret->b_assoc_buffers); |
736c7b80 | 3194 | get_cpu_var(bh_accounting).nr++; |
1da177e4 | 3195 | recalc_bh_state(); |
736c7b80 | 3196 | put_cpu_var(bh_accounting); |
1da177e4 LT |
3197 | } |
3198 | return ret; | |
3199 | } | |
3200 | EXPORT_SYMBOL(alloc_buffer_head); | |
3201 | ||
3202 | void free_buffer_head(struct buffer_head *bh) | |
3203 | { | |
3204 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3205 | kmem_cache_free(bh_cachep, bh); | |
736c7b80 | 3206 | get_cpu_var(bh_accounting).nr--; |
1da177e4 | 3207 | recalc_bh_state(); |
736c7b80 | 3208 | put_cpu_var(bh_accounting); |
1da177e4 LT |
3209 | } |
3210 | EXPORT_SYMBOL(free_buffer_head); | |
3211 | ||
1da177e4 LT |
3212 | static void buffer_exit_cpu(int cpu) |
3213 | { | |
3214 | int i; | |
3215 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3216 | ||
3217 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3218 | brelse(b->bhs[i]); | |
3219 | b->bhs[i] = NULL; | |
3220 | } | |
8a143426 ED |
3221 | get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; |
3222 | per_cpu(bh_accounting, cpu).nr = 0; | |
3223 | put_cpu_var(bh_accounting); | |
1da177e4 LT |
3224 | } |
3225 | ||
3226 | static int buffer_cpu_notify(struct notifier_block *self, | |
3227 | unsigned long action, void *hcpu) | |
3228 | { | |
8bb78442 | 3229 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) |
1da177e4 LT |
3230 | buffer_exit_cpu((unsigned long)hcpu); |
3231 | return NOTIFY_OK; | |
3232 | } | |
1da177e4 | 3233 | |
389d1b08 | 3234 | /** |
a6b91919 | 3235 | * bh_uptodate_or_lock - Test whether the buffer is uptodate |
389d1b08 AK |
3236 | * @bh: struct buffer_head |
3237 | * | |
3238 | * Return true if the buffer is up-to-date and false, | |
3239 | * with the buffer locked, if not. | |
3240 | */ | |
3241 | int bh_uptodate_or_lock(struct buffer_head *bh) | |
3242 | { | |
3243 | if (!buffer_uptodate(bh)) { | |
3244 | lock_buffer(bh); | |
3245 | if (!buffer_uptodate(bh)) | |
3246 | return 0; | |
3247 | unlock_buffer(bh); | |
3248 | } | |
3249 | return 1; | |
3250 | } | |
3251 | EXPORT_SYMBOL(bh_uptodate_or_lock); | |
3252 | ||
3253 | /** | |
a6b91919 | 3254 | * bh_submit_read - Submit a locked buffer for reading |
389d1b08 AK |
3255 | * @bh: struct buffer_head |
3256 | * | |
3257 | * Returns zero on success and -EIO on error. | |
3258 | */ | |
3259 | int bh_submit_read(struct buffer_head *bh) | |
3260 | { | |
3261 | BUG_ON(!buffer_locked(bh)); | |
3262 | ||
3263 | if (buffer_uptodate(bh)) { | |
3264 | unlock_buffer(bh); | |
3265 | return 0; | |
3266 | } | |
3267 | ||
3268 | get_bh(bh); | |
3269 | bh->b_end_io = end_buffer_read_sync; | |
3270 | submit_bh(READ, bh); | |
3271 | wait_on_buffer(bh); | |
3272 | if (buffer_uptodate(bh)) | |
3273 | return 0; | |
3274 | return -EIO; | |
3275 | } | |
3276 | EXPORT_SYMBOL(bh_submit_read); | |
3277 | ||
b98938c3 | 3278 | static void |
51cc5068 | 3279 | init_buffer_head(void *data) |
b98938c3 CL |
3280 | { |
3281 | struct buffer_head *bh = data; | |
3282 | ||
3283 | memset(bh, 0, sizeof(*bh)); | |
3284 | INIT_LIST_HEAD(&bh->b_assoc_buffers); | |
3285 | } | |
3286 | ||
1da177e4 LT |
3287 | void __init buffer_init(void) |
3288 | { | |
3289 | int nrpages; | |
3290 | ||
b98938c3 CL |
3291 | bh_cachep = kmem_cache_create("buffer_head", |
3292 | sizeof(struct buffer_head), 0, | |
3293 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3294 | SLAB_MEM_SPREAD), | |
3295 | init_buffer_head); | |
1da177e4 LT |
3296 | |
3297 | /* | |
3298 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3299 | */ | |
3300 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3301 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3302 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3303 | } | |
3304 | ||
3305 | EXPORT_SYMBOL(__bforget); | |
3306 | EXPORT_SYMBOL(__brelse); | |
3307 | EXPORT_SYMBOL(__wait_on_buffer); | |
3308 | EXPORT_SYMBOL(block_commit_write); | |
3309 | EXPORT_SYMBOL(block_prepare_write); | |
54171690 | 3310 | EXPORT_SYMBOL(block_page_mkwrite); |
1da177e4 LT |
3311 | EXPORT_SYMBOL(block_read_full_page); |
3312 | EXPORT_SYMBOL(block_sync_page); | |
3313 | EXPORT_SYMBOL(block_truncate_page); | |
3314 | EXPORT_SYMBOL(block_write_full_page); | |
89e10787 | 3315 | EXPORT_SYMBOL(cont_write_begin); |
1da177e4 LT |
3316 | EXPORT_SYMBOL(end_buffer_read_sync); |
3317 | EXPORT_SYMBOL(end_buffer_write_sync); | |
3318 | EXPORT_SYMBOL(file_fsync); | |
1da177e4 | 3319 | EXPORT_SYMBOL(generic_block_bmap); |
05eb0b51 | 3320 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 LT |
3321 | EXPORT_SYMBOL(init_buffer); |
3322 | EXPORT_SYMBOL(invalidate_bdev); | |
3323 | EXPORT_SYMBOL(ll_rw_block); | |
3324 | EXPORT_SYMBOL(mark_buffer_dirty); | |
3325 | EXPORT_SYMBOL(submit_bh); | |
3326 | EXPORT_SYMBOL(sync_dirty_buffer); | |
3327 | EXPORT_SYMBOL(unlock_buffer); |